I am new to this place and i have bought a 98 chevy z28 with the LS1 and i a wanting to increase hp and not decrease the money. Please help

It depends on what you are looking for. If your looking for something easy to hook up that will give you a nice bump in performance go with a supercharger. If you are looking for a kit that will deliver most possible potential in horsepowe but that will probably cost a bit more cause of the engineering that went into designing the kit go turbo.

Either way boost is boost and a turbo will not eat up as much of the potential power but will probably generate slightly higher engine bay temps and cost a tad more.

Also what do you mean by decrease money. You mean value of the vehicle?. Cause vehicles with turbo's and superchargers generally sell for higher than stock vehicles.

PS- Welcome to AF.

Either way you go you're looking at spending between $4k-$6k. Each option has its pros and cons. for the S/C the pros are cooler inlet air temps, less problems with convection heat and simple belt & pulley changes to alter the boost psi.and almost instant boost. Cons are parasitic loss of some of the HP from turning the blower and limited pressures (on under hood designs).
For the turbo pros are more mounting location options, no parasitic drag, usually smaller in design. Cons are high temps, changing boost pressure usually takes a larger turbo, turbo lag and more parts involved.

Also what do you mean by decrease money. You mean value of the vehicle?. Cause vehicles with turbo's and superchargers generally sell for higher than stock vehicles.



i think he means... he doesnt wanna decrease his pockets

Forced induction won't be cheap on any car.
Plus, you'll probably want a tune and bolt-on's to support the extra flow.
But on stock internals, you'll only be able to run 6-8 pounds of boost anyway, and Formula is right, boost is boost.

turbo. accept no other.

turbo. accept no other.Turbo is not always the best option here. Especially with F-bodys. Besides I would rather buy a supercharger kit for 2500 - 3000 than a turbo kit for 4000 - 6000 and have maybe 15 - 25 less horse (which can be made up other ways very easily.). Not to mention less underhood temps , easier install in most cases and easier to turn up the boost (only requires a pulley change in most cases assuming you haven't hit the max spin and cfm of your blower).

Turbo is not always the best option here. Especially with F-bodys. Besides I would rather buy a supercharger kit for 2500 - 3000 than a turbo kit for 4000 - 6000 and have maybe 10 - 15 less horse (which can be made up other ways very easily.). Not to mention less underhood temps , easier install in most cases and easier to turn up the boost (only requires a pulley change in most cases assuming you haven't hit the max spin and cfm of your blower).

fair enough, i just like turbos over blowers for certain reasons.

fair enough, i just like turbos over blowers for certain reasons.

the sound...

















i hate how superchargers sound

the sound...

















i hate how superchargers sound


Very true. There's a TT supra that drifts at the track around here, and it sounds amazing. I am a big fan of turbo's, but FormulaLT1 brought up some awesome points. If you were on a real tight budget, go supercharger and make the power in other(cheaper) areas.

any type of forced induction will not be cheap. bolt ons are almost mandatory to support and take full advantage of a blower or turbo. a supercharger kit will be cheaper and easier to install. One of the best turbo kits for the late model f-body is the STS system which locates the turbo in place of the muffler. that reduces under hood temps and saves space under the hood. either way you are looking at $3,000-$6,000 for a kit and some supporting bolt ons.

any type of forced induction will not be cheap. bolt ons are almost mandatory to support and take full advantage of a blower or turbo. a supercharger kit will be cheaper and easier to install. One of the best turbo kits for the late model f-body is the STS system which locates the turbo in place of the muffler. that reduces under hood temps and saves space under the hood. either way you are looking at $3,000-$6,000 for a kit and some supporting bolt ons.

STS is a revolutionary idea and i love it, except, im a fan of the dual exhaust look. and STS places the air intake on the left side right where the left exhaust tip would be. so you're left with a nice beautiful shiny single pipe sticking out the right side

remote turbo? not as efficient as a manifold-mounted one.

and c'mon, a turbo 7-ft away from the engine?

any type of forced induction will not be cheap. bolt ons are almost mandatory to support and take full advantage of a blower or turbo. a supercharger kit will be cheaper and easier to install. One of the best turbo kits for the late model f-body is the STS system which locates the turbo in place of the muffler. that reduces under hood temps and saves space under the hood. either way you are looking at $3,000-$6,000 for a kit and some supporting bolt ons.
One of the main factors in providing turbine pressure using a turbo is heat. The closer you are to the exhaust port the more energy/heat you have. STS design is not as efficient as a convenential turbo but yes much like a supercharger it works cause it meets certain needs. Like the issue of engine bay space and heat. However these kits cost 4k + and have a higher percentage of pressure leaks on both the exhaust (drive side) and the intake (PSI side). However on the other hand you can purchase lets say a powerdyne supercharger kit for around 2400 - 2600 that will provide 4.5 PSI and with a 90 -110 dollar pulley change will provide 6 + PSI (you can also be smart and use the 4.5 pulley for every day driving and only use the 6PSI pulley on track days).

Again, I am all for turbo in 99.99% of the cases. Because they are more efficient and use mostly unused energy to drive them. They usually also provide power at a range that is more usable without creating tractions issue's and in most cases are easier fabrication wise to get in there somewhere when space isn't a issue.

Now with that said, F-body's use large displacement engine's in already cramped to near max engine bays and because of this extreme, it is in dangerously close quarters to vital engine/wiring components, more piping/plumbing components complicates routing and find room to route things and because of this more time to design a practical kit is required. Time=money. Then you run into issue like needing a intercooler because of the higher intake temps of a turbo.

I looked and weighed all factors in my decision and would have loved to go turbo because it is the superior design of the two but in my case and many other f-body owners IMO. Supercharger is the more practical boost method.

where there's a will, there's a way.

my friend taught me that. pushing figures on some engines i couldn't even imagine.

I was all set to go turbo. I was actually suppose to send Andy/Hypsi some headers I wasn't using and he was going to fab them up into turbo headers for me :frown: , Unfortunetly we know why that didn't come to be.

However the supercharger simplified things for me and I am not looking for a single digit dragster. Just a 10 second street/strip car :smooch: .

both have advantages and drawbacks so it really comes down to your budget and preference. i like both but i think most go for a blower because of the price and simpler install.

supercharging is cheap and easy to install.

turbo is really the way to go, it offers better toque gains at low rpm (with correct turbo sizing or variable-vane blowers) and many ball bearing turbos offer almost instant response and zero lag. if you can get the space issue sorted (you should be able to) then turbo is the option for power and torque, otherwise if you want a quick fix with a tried and tested method then use supercharging.

supercharging's advantage is its instant response, but they produce max boost at max rpm, whereas a turbo can produce max boost at say, 2,500rpm in certain cases, even lower in others. the disadvantage is that they use some of the power they produce. they are sometimes only 75% efficient. a turbo is 100% efficient as it's not "driven" so to speak.

if you are going to stick with stock internals, and probably not exceed 8psi boost, there is no reason to go with a turbo. a supercharger is simpler and cheaper, and provides that kind of boost. you can tune the boost by changing a pully, and dont need a BOV. to limit a turbo to 8 psi, you would be venting a lot of boost with some sort of boost control valve, unless you used an itsy bitsy turbo... supercharger is better for this case.


oh, and as for the sound issue, you have two options, first, spend the saved money on your stereo system, or, get a cetrifugal supercharger, and much the same sound as a turbo.

p.s.
i didnt mean to say that you didnt need a bov with a supercharger, but that you dont need one to control boost levels. sorry about any confusion

What is all this talk of blower intake temps being colder than turbo intake temps?

And what is this talk of having to change turbos to change boost levels?

One of the main factors in providing turbine pressure using a turbo is heat. The closer you are to the exhaust port the more energy/heat you have. STS design is not as efficient as a convenential turbo but yes much like a supercharger it works cause it meets certain needs. Like the issue of engine bay space and heat. However these kits cost 4k + and have a higher percentage of pressure leaks on both the exhaust (drive side) and the intake (PSI side). However on the other hand you can purchase lets say a powerdyne supercharger kit for around 2400 - 2600 that will provide 4.5 PSI and with a 90 -110 dollar pulley change will provide 6 + PSI (you can also be smart and use the 4.5 pulley for every day driving and only use the 6PSI pulley on track days).

Again, I am all for turbo in 99.99% of the cases. Because they are more efficient and use mostly unused energy to drive them. They usually also provide power at a range that is more usable without creating tractions issue's and in most cases are easier fabrication wise to get in there somewhere when space isn't a issue.

Now with that said, F-body's use large displacement engine's in already cramped to near max engine bays and because of this extreme, it is in dangerously close quarters to vital engine/wiring components, more piping/plumbing components complicates routing and find room to route things and because of this more time to design a practical kit is required. Time=money. Then you run into issue like needing a intercooler because of the higher intake temps of a turbo.

I looked and weighed all factors in my decision and would have loved to go turbo because it is the superior design of the two but in my case and many other f-body owners IMO. Supercharger is the more practical boost method.

:screwy: I can STAND in the front of my damn engine bay! hehehe

Just a 10 second street/strip car :smooch: .

There are 3 tracks in this state, 1 of which is real close to you, stop bench racing and put some numbers up already!

if you are going to stick with stock internals, and probably not exceed 8psi boost, there is no reason to go with a turbo. a supercharger is simpler and cheaper, and provides that kind of boost. you can tune the boost by changing a pully, and dont need a BOV. to limit a turbo to 8 psi, you would be venting a lot of boost with some sort of boost control valve, unless you used an itsy bitsy turbo... supercharger is better for this case.


oh, and as for the sound issue, you have two options, first, spend the saved money on your stereo system, or, get a cetrifugal supercharger, and much the same sound as a turbo.

p.s.
i didnt mean to say that you didnt need a bov with a supercharger, but that you dont need one to control boost levels. sorry about any confusion

you are aware I hope, that 8 psi on a blower and 8psi on a turbo are not at all the same?

:screwy: I can STAND in the front of my damn engine bay! hehehe
Right but we are talking about the big boy engine :iceslolan . lol, jk. I was referring to the LS1 and LT1 but even the 6's are cramped as well but yet have more room than the V8''s but also lets not forget you are like 2 feet tall :loser: . :rofl:

you are aware I hope, that 8 psi on a blower and 8psi on a turbo are not at all the same?How much of a horsepower difference do you think we are talking about here and are we comparing CFM to unit or just parastic loss? because CFM would vary depending on the turbo and supercharger model and if this is the case 8PSI on a supercharger could potentially make more power than 8PSI on a turbo.

What is all this talk of blower intake temps being colder than turbo intake temps?

And what is this talk of having to change turbos to change boost levels?
Sorry I missed this post but since the first part was something I had said. Do you think that the snail does not heat soak and transfer that hotter driven air into your intake manifold?. Ofcourse a intercooler is a relatively easy fix for this problem but yet more space taken up and more plumbing. Also on supercharger or turbo , anything above 10PSI you are heating the air hot enough that a intercooler is necessary but due to the already high compression ratio of both LT1 and LS1 that we were referring to. It is highly discouraged using anything above 8 PSI (and I would not even want to go that high on these engines with stock internals, I wouldn't go any higher than 6PSI)

you are aware I hope, that 8 psi on a blower and 8psi on a turbo are not at all the same?

How much of a horsepower difference do you think we are talking about here and are we comparing CFM to unit or just parastic loss? because CFM would vary depending on the turbo and supercharger model and if this is the case 8PSI on a supercharger could potentially make more power than 8PSI on a turbo.
why is this?
i thought that boost was boost

why is this?
i thought that boost was boost
Boost is boost if we are comparing same sized units. Obviously you wouldn't run a 4 cyc's turbo capable of a max 500CFM on a V8 that already is vacuuming 450CFM. What you would be doing is over spinning the hell out of it to show any boost at all and what boost you were making would just basically be making up for the lose of flow in the exhaust track and heating up the air. However if you put in a unit capable of delivering 1200 CFM, now you are delivering some real flow down the engines throat and would see great gains.

This is why any reputable force induction specialist will tell you to research what mods you plan on doing (such as cam, heads , TB, injectors, BASIC vacuum/flow CFM) then pick a turbo that will be able to deliver the amount of air and pressure that you would like to run.

i was mainly refering to the statement that 8psi on a turbo was different than 8psi on a supercharger

Sorry I missed this post but since the first part was something I had said. Do you think that the snail does not heat soak and transfer that hotter driven air into your intake manifold?. Ofcourse a intercooler is a relatively easy fix for this problem but yet more space taken up and more plumbing. Also on supercharger or turbo , anything above 10PSI you are heating the air hot enough that a intercooler is necessary but due to the already high compression ratio of both LT1 and LS1 that we were referring to. It is highly discouraged using anything above 8 PSI (and I would not even want to go that high on these engines with stock internals, I wouldn't go any higher than 6PSI)
You have some very bizarre concepts there.
A turbo can acheive into the high 70% for compressor efficiency, that is a direct measurement of how hot the air gets for the amount it is compressed.
A supercharger is not more efficient at compressing air, most are less efficient which means the air coming out of them is hotter.

Boost is boost.
If your engine sees 8psi at say 60 deg C at the intake manifold then it doesn't give a damn what the flow capacity of the device that's providing that 8psi is.

If your boost device can't provide the flow, then that shows as a pressure drop. If it can provide the flow but at lower efficiency then that shows up as an increase in boost temps.

*edit*
Now before you guys start on another tangent, I haven't mentioned "power" anywhere in this post.

You have some very bizarre concepts there.
A turbo can acheive into the high 70% for compressor efficiency, that is a direct measurement of how hot the air gets for the amount it is compressed.
A supercharger is not more efficient at compressing air, most are less efficient which means the air coming out of them is hotter.

Boost is boost.
If your engine sees 8psi at say 60 deg C at the intake manifold then it doesn't give a damn what the flow capacity of the device that's providing that 8psi is.

If your boost device can't provide the flow, then that shows as a pressure drop. If it can provide the flow but at lower efficiency then that shows up as an increase in boost temps.

*edit*
Now before you guys start on another tangent, I haven't mentioned "power" anywhere in this post.
Who said that a supercharger was more efficient at compressing air?. I believe what I said, was a turbo is the more efficient system if you reread what I wrote. You would have to look at a compressor map (cfm/psi) to figure out unit to unit which one create more "power" (which you stated you didn't mention but that is my point that your missing). While boosted pressure may be boost pressure. The air behind that boost may not be the same. Two unit being equal CFM/PSI wise one a supercharger and one a turbo, I think its pretty obvious the turbo will be the one making more power.

However based on the thread starters question and affordability versus ease of install and potential. I stated in this case (which is rare) that the supercharger is the more practical way to go.

Edit- Also while two of the same unit making the same boost/cfm, one a turbo & one a supercharger. The turbo will most certainly have higher IAT than the supercharger. I thought that was pretty commen knowledge.

Who said that a supercharger was more efficient at compressing air?.
You did, you've done it again right here.

The turbo will most certainly have higher IAT than the supercharger. I thought that was pretty commen knowledge.

You did, you've done it again right here.What hell do iat have to do with how much boost and CFM each unit is pumping? :screwy: (and how much power they are taking to drive them). I can take a propane torch to my intake elbow to raise air temp, does that mean my supercharger is being less efficient than it normally is?

What hell do iat have to do with how much boost and CFM each unit is pumping? :screwy: (and how much power they are taking to drive them). I can take a propane torch to my intake elbow to raise air temp, does that mean my supercharger is being less efficient than it normally is?

The efficiency of an air compressor is measured by how much extra heat is put into the air.

You're saying that a turbo is more efficient but the outlet temps are higher than a supercharger.
For that to happen you'd need a huge amount of heat transfer, much more than I believe occurs.

The efficiency of an air compressor is measured by how much extra heat is put into the air.

You're saying that a turbo is more efficient but the outlet temps are higher than a supercharger.
For that to happen you'd need a huge amount of heat transfer, much more than I believe occurs.
I'll tell you what, go run your car for 5 minutes then grab onto your exhaust manifold. While your hand is sizzling like a slice of bacon in the fryer think about what that heat from the passing exhaust gas and manifold/header is doing to your turbo housing. Then think of pumping air from inside a oven, versus pumping air from outside a window, which do you think is going to be hotter?.

Yes, as the air is being compressed it is heated but when you are starting with already hot air, the effect of compressing it raises the temps even higher. This is why the supercharger has lower temps than the turbo, however like I said you run a intercooler and the air is cooled by the passing air while you are driving lowering the temps to similiar or possibly lower than the supercharger (depending on how good of a unit you have) but this takes up space and cost money.

Things I said kinda discourage the advantage in the case of the f-body.

I'll tell you what, go run your car for 5 minutes then grab onto your exhaust manifold. While your hand is sizzling like a slice of bacon in the fryer think about what that heat from the passing exhaust gas and manifold/header is doing to your turbo housing. Then think of pumping air from inside a oven, versus pumping air from outside a window, which do you think is going to be hotter?.

Yes, as the air is being compressed it is heated but when you are starting with already hot air, the effect of compressing it raises the temps even higher. This is why the supercharger has lower temps than the turbo, however like I said you run a intercooler and the air is cooled by the passing air while you are driving lowering the temps to similiar or possibly lower than the supercharger (depending on how good of a unit you have) but this takes up space and cost money.

Things I said kinda discourage the advantage in the case of the f-body.

I don't need to do anything as silly as putting my hand on the exhaust pipe. See I have temp probes which fit into my intake pipes just before the inlet manifold.

So instead of talking about what "might" happen with regards to heat transfer, I know what does happen.

And yes getting air out of a turbo at temps which equate to better than 70% efficiency is not a problem.:wink:

I don't need to do anything as silly as putting my hand on the exhaust pipe. See I have temp probes which fit into my intake pipes just before the inlet manifold.

So instead of talking about what "might" happen with regards to heat transfer, I know what does happen.

And yes getting air out of a turbo at temps which equate to better than 70% efficiency is not a problem.:wink:
For you to know what is actually happening compared to what you "think" is happening you would need to run a controlled study of the two. Which has been done. So while you are free to believe what ever you want to believe don't criticize others fact based on research by your belief of what happens on both systems in regards to what you noticed in your case.

Fact of the matter is you have no idea what the IAT's would be with the same pressure and cfm using a supercharger compared to your turbo.

Bottom line, it has been said and proven countless times, turbo's are more efficient. They can create the same amount of pressurized air while only requiring a tiny fraction of that to run. That is not in question nor has been stated otherwise by myself.

There are advantages to both system, in different cases and I am saying money/space vs. potential power advantage does not always make the strong case for turbo in relation to "F-bodys".

I think I just grew a tumor after reading this thread

Fact of the matter is you have no idea what the IAT's would be with the same pressure and cfm using a supercharger compared to your turbo.

Why do you think I have no idea?
I have supercharger compressor maps, turbo charger compressor maps and Ihave actual measurements to verify the outlet temps for a turbo.

All the data says a centrifugal supercharger could only equal that, not better it.

Why do you think I have no idea?
I have supercharger compressor maps, turbo charger compressor maps and Ihave actual measurements to verify the outlet temps for a turbo.

All the data says a centrifugal supercharger could only equal that, not better it.We are talking intake air temps. Temps of the air leaving the pressure side versus temps leaving the pressure side. Am I not saying this in english or something ? :dunno: . You can't look at one temp and know what the other unit generates based on what your unit is doing .

You know what, I am getting frustrated here. So your right, turbo's have lower intake air temps :screwy: and I lied and said somewhere (even though I must have missed ever saying this in my whole life) that superchargers are way more efficient than turbo's :rolleyes:.

Ok thats better. Not true but better.

turbo is better

my reasoning: i'm smarter than you and you should listen to me

turbo is better

my reasoning: i'm smarter than you and you should listen to me

you also come across as stuck-up and you're not in the least bit funny.

We are talking intake air temps. Temps of the air leaving the pressure side versus temps leaving the pressure side. Am I not saying this in english or something ? :dunno: . You can't look at one temp and know what the other unit generates based on what your unit is doing .

I am also talking about engine inlet temps. When I'm referring to "outlet", I'm referring to the outlet of the turbo (or supercharger) compressor. I didn't bother to clarify that point earlier because it is quite obvious.

Data is published for both supercharger compressors and turbo compressors by their manufacturers.

The data says turbos are more efficient and pump out colder air.
I have taken temperature measurements and performed calculations to verify the efficiency and outlet temps of my turbos.

I don't see which part of that isn't straightforward and easy to understand.

Well, I have read info to the contrary and controlled studys of both that yielded lower output temp via the supercharger application, I guess it all depends on what you "choose" to believe using commen sense vs. what someone believe's to the case on old unconfirmed information but just look at STS alone claim of there rear mounted turbo kits providing lower intake temps due to location change. Is this due to there turbo set up being more efficient?

Well, I have read info to the contrary and controlled studys of both that yielded lower output temp via the supercharger application,

I would like to read this study. Do you have a link for me?

I would like to read this study. Do you have a link for me?There is a google search bar listed right in this page. Do some searching,. I can start you off on the first link though, http://www.superchargersonline.com/content.asp?ID=19 (I am sure you are going to say that because it is a site based on superchargers it will be biased notice he still states the turbo is the more efficient unit)

Edit- Also read this or just skip ahead to the intercooler section http://www.turbomustangs.com/turbotech/main.htm

Quoted from this article ( http://www.autofieldguide.com/articles/050103.html )on why car manufacturer are looking at forced induction to increase efficiency "a supercharger has a few advantages over a turbo, says Streeter. "First, it doesn't soak up exhaust heat "

There is a google search bar listed right in this page. Do some searching,. I can start you off on the first link though, http://www.superchargersonline.com/content.asp?ID=19 (I am sure you are going to say that because it is a site based on superchargers it will be biased notice he still states the turbo is the more efficient unit)

Edit- Also read this or just skip ahead to the intercooler section http://www.turbomustangs.com/turbotech/main.htm

Quoted from this article ( http://www.autofieldguide.com/articles/050103.html )on why car manufacturer are looking at forced induction to increase efficiency "a supercharger has a few advantages over a turbo, says Streeter. "First, it doesn't soak up exhaust heat "

Those references contain only hand waving, generalisations and interviews with supercharger salesmen.

Do you have nothing more to offer? Like actual measurements of boost temps?

Those references contain only hand waving, generalisations and interviews with supercharger salesmen.

Do you have nothing more to offer? Like actual measurements of boost temps?
Like I said do some research,,. I would also like to state that one of those links was made by a site aimed at Turbo enthusiasts and the other two talked about advantages of the turbo as well,. Do some research. You are obviously believing what you want to believe versus actual conditions based on common sense.

This thread is pretty much done. I expressed my thoughts (as well as others did) and posted up 3 links that back up my statement, anyone choosing to believe it or not , thats there choice.


Edit- Upon further thought, I am reopening this topic but anyone offering opposing view point and/or stating info is biased or incorrect. Please back up your statements with resources of technical nature to show you are not just choosing to believe what you want to believe. Instead of just requesting sources for others info and then belittling those sources,.

Also I would just like to point out I subscribe and read several different engineering publications. I traffic several different automotive tech sites. It would be damn near impossible for me to pin point and find at the drop of a hat any and all sources that I have read online as well as in paper form. However I don't form opinions at the drop of the hat, I base them on what I believe to be proven fact from knowledgeable sources on the topic.

There is a google search bar listed right in this page. Do some searching,. I can start you off on the first link though, http://www.superchargersonline.com/content.asp?ID=19 (I am sure you are going to say that because it is a site based on superchargers it will be biased notice he still states the turbo is the more efficient unit)…

That first links says the following in regards to heat transfer:


Because the turbocharger is mounted to the exhaust manifold (which is very hot), turbocharger boost is subject to additional heating via the turbo's hot casing… A centrifugal supercharger on the other hand creates a cooler air discharge, so an intercooler is often not necessary at boost levels below 10psi. That said, some superchargers (especially roots-type superchargers) create hotter discharge temperatures, which also make an intecooler necessary even on fairly low-boost applications.

I believe the above is the point you are trying to make. That the compressor efficiency on the turbocharger is higher than that of a supercharger, however heat transfered from the turbine side of the unit creates additional temperature rise in the IAT.

This topic was brought up a while back in this thread:
http://www.automotiveforums.com/vbulletin/showthread.php?t=399086

I never did get a satisfactory answer on how heat is transferred from the ‘hot-side’ of the turbocharger to the ‘cold-side’. Nor have I heard of any effort to minimize the heat transfer. If it has such a negative impact on the turbocharger’s performance I would think it would possible to insulate the compressor from the exhaust heat.

This topic was brought up a while back in this thread:
http://www.automotiveforums.com/vbulletin/showthread.php?t=399086

I never did get a satisfactory answer on how heat is transferred from the ‘hot-side’ of the turbocharger to the ‘cold-side’. Nor have I heard of any effort to minimize the heat transfer. If it has such a negative impact on the turbocharger’s performance I would think it would possible to insulate the compressor from the exhaust heat.

IME it's a myth with no basis.
The measurements I have taken show turbo outlet temps are not significantly hotter than the compressor alone (without being attached to a turbo) will produce.

The cold side of the turbo is connected to the hot side by:
- A steel shaft of maybe 8mm diameter (not a great conductor) which is bathed in oil.
- A housing which is cooled by large flows of engine oil at a temp of less than 100 deg C.
- A housing that is often cooled by large flows of engine coolant at a temp of less than 100 deg C.

A turbo running at 15psi has outlet temps around 100 deg C. That's a higher temp than the oil and water which are used for cooling.

So where is this large amount of heat-soak coming from again?

IME it's a myth with no basis.
The measurements I have taken show turbo outlet temps are not significantly hotter than the compressor alone (without being attached to a turbo) will produce.

The cold side of the turbo is connected to the hot side by:
- A steel shaft of maybe 8mm diameter (not a great conductor) which is bathed in oil.
- A housing which is cooled by large flows of engine oil at a temp of less than 100 deg C.
- A housing that is often cooled by large flows of engine coolant at a temp of less than 100 deg C.

A turbo running at 15psi has outlet temps around 100 deg C. That's a higher temp than the oil and water which are used for cooling.

So where is this large amount of heat-soak coming from again?

Those are interesting results.

Out of curiosity, what did you use to measures those temperatures and where in the flow were the measurements taken?

Those are interesting results.

Out of curiosity, what did you use to measures those temperatures and where in the flow were the measurements taken?

I used 3 wire temp sensors (can't recall the model right now) through a serial data logger to my laptop.

I had a sensor at the front corner of the engine bay, one protruding about 15mm into the piping about 150mm from the turbo exit and again about 400mm further down after the air-water intercooler.

the simple test for this is to run the engine hard, then jump out and put your hand on the compressor housing (not the exhaust housing)

You will find that its luke warm.

You could argue that this is because the air charge is taking all the heat away from the compressor housing, and putting it into the air charge, but this....theory....is ignoring the temp differential that would be present with such a situation.

As kiwi said, it looks good on paper, but doesn't hold any water in the real world.

the simple test for this is to run the engine hard, then jump out and put your hand on the compressor housing (not the exhaust housing)

You will find that its luke warm.

You could argue that this is because the air charge is taking all the heat away from the compressor housing, and putting it into the air charge, but this....theory....is ignoring the temp differential that would be present with such a situation.




That sounds about right.
I remember hopping out of one of my cars while it was idling after a run on the highway, and pointing a laser thermometer at the turbine and then at the compressor housing and got something like ~660F at the turbine and maybe ~120 at the compressor.
If anybody cares, I can check it again.........

you also come across as stuck-up and you're not in the least bit funny.

cool...and i care why?

once you have a supercharged and a turbocharged car, then you can talk...i have a turbo GSR, it is a blast to drive. My buddy Ryan has a SC'd GSR...it is lame. I rode in it before i decided to turbo and it was slow as shit....therefore i went turbo.

On the other hand, my buddy Taylor has a Procharged Mustang and it is fast as hell....he ran an 11.8 w/ slicks and the SC...the rest of the car is stock. Superchargers have a place, but honestly i'd much rather turbo a car. Mine and Taylor's next project is a GT4088R 5.0L Mustang (fox body for those who care)

Lets all try to stay respectable guys.

Also to the topic at hand. It depends on alot of variables which is the better choice. Most important usually being cost followed by bay room but it also depends on supercharger model to turbo model. Obviously different supercharger with different pulleys are going to have different characteristics and same can be said of different turbo models.

We also have to look (like was pointed out, which engine is driving them). A 4 Cyc, V6 & V8 + will obviously produce different results on each. To each there own, we can all make recommendations on which we think best suits us and someone else but if power is the name of the game turbo will always be the way to go. If Ease of install (and in this case money) with added performance is your preference then a supercharger may work for you.

Each have there place and purpose but IMO they both meet the same need for different people and once driven the process of injecting that boost is identical (in centrifugal units that is)

I've seen a few articles where they take the same engine and mount different forced air systems and dyno them all at the same boost setting.

A SC (of any type) should be not terribly far off from a turbo at simular psi. The higher efficiency of a turbo, realistically, isn't a HUGE difference, not until you start getting into the really high boost numbers.

To me, its the mid range that really seperates them. Once the turbo spools, it will produce a lot more torque than either type of supercharger. The roots-style will be not too far behind, because of their linear application of boost, but the paxton/vortecs will be way below the mark, assuming the turbo is sized realistically.

The one article I'm thinking of, the paxton actually beat the turbo in peak power, but just barely, and only at redline. But the turbo made 100+ more ft/lb's in the mid range. When comparing the two graphs average HP, there was no comparison.

I can definitely see an advantage of having the paxton on a larger engine though. Sometimes, you don't want a huge hitting boost curve, because you already have traction issues as it is. A paxton is very linear and could probably keep the tires in check a lot better, but still have good peak power.

the main reason i dont like superchargers is because they're not as easily upgradable as a turbo...i would have to either get a smaller pulley or replace the entire SC in order to make more power. With my turbo setup, all i need is a different turbo, different injectors and a retune...

Also, roots and Twinscrew SC's heatsoak which limits them....FMIC FTW

one of the main concerns/complaints people have w/ turbo cars is that the tend to lag...well if you properly size a turbo to an engine, it can have the same linnear powerband as a supercharger, but push a lot more air up top. When you start getting into higher HP turbo 4's you see some pretty large turbos (i.e. GT35R, GT40R, BW S300 series and so on)...at that point, you're going to have some lag, but lag isn't always bad.

My turbo lag is my traction!

Also, roots and Twinscrew SC's heatsoak which limits them....FMIC FTW

you are aware that turbos heatsoak, right?

think about it, at full throttle exhaust gases leave the engine at ~1,000 deg C sometimes. the exhaust housing is fixed to the compressor housing, which soaks the heat and raises intake temps.

you are aware that turbos heatsoak, right?

think about it, at full throttle exhaust gases leave the engine at ~1,000 deg C sometimes. the exhaust housing is fixed to the compressor housing, which soaks the heat and raises intake temps.

Nice of you to skip reading the previous four pages.:screwy:

I've seen a few articles where they take the same engine and mount different forced air systems and dyno them all at the same boost setting.

A SC (of any type) should be not terribly far off from a turbo at simular psi. The higher efficiency of a turbo, realistically, isn't a HUGE difference, not until you start getting into the really high boost numbers.

To me, its the mid range that really seperates them. Once the turbo spools, it will produce a lot more torque than either type of supercharger. The roots-style will be not too far behind, because of their linear application of boost, but the paxton/vortecs will be way below the mark, assuming the turbo is sized realistically.

The one article I'm thinking of, the paxton actually beat the turbo in peak power, but just barely, and only at redline. But the turbo made 100+ more ft/lb's in the mid range. When comparing the two graphs average HP, there was no comparison.

I can definitely see an advantage of having the paxton on a larger engine though. Sometimes, you don't want a huge hitting boost curve, because you already have traction issues as it is. A paxton is very linear and could probably keep the tires in check a lot better, but still have good peak power.
Out of curiosity which series or model Paxton was this?. I currently am running a paxton but a older model, however I have seen results of the older paxtons producing more horsepower at the same boost levels. Which I find crazy cause the newer units takes less power to drive.

Out of curiosity which series or model Paxton was this?. I currently am running a paxton but a older model, however I have seen results of the older paxtons producing more horsepower at the same boost levels. Which I find crazy cause the newer units takes less power to drive.

I don't recall honestly, but keep in mind they only used one example for each type of forced induction. The roots was undersized and they were having trouble even getting 10psi out of it. The turbo was slightly undersized and was out of its efficiency range at redline.

Since the paxtons are pretty much compressor wheels off turbo's, they are just as efficient at the right output as a well sized turbo, so I wasn't terribly surprised by the results (peak HP)

I don't recall honestly, but keep in mind they only used one example for each type of forced induction. The roots was undersized and they were having trouble even getting 10psi out of it. The turbo was slightly undersized and was out of its efficiency range at redline.

Since the paxtons are pretty much compressor wheels off turbo's, they are just as efficient at the right output as a well sized turbo, so I wasn't terribly surprised by the results (peak HP)
Which is what I was saying prior. Its basically (centrifugal units) a turbo driven by a pulley. So while the percentage of power to drive will be slightly higher on a supercharger, the turbo has the potential to be the more efficient unit. When comparing equal CFM delivering potential.

you are aware that turbos heatsoak, right?

think about it, at full throttle exhaust gases leave the engine at ~1,000 deg C sometimes. the exhaust housing is fixed to the compressor housing, which soaks the heat and raises intake temps.

Well considering I have one on my car and regularly build turbo cars as a hobby, i think i might have known that. :screwy:

The difference in the heat soak in my turbo and a supercharger is that on MOST twinscrew and roots sc's you can't run an inter/aftercooler, while on my turbo setup, i run a large front mount which keeps my intake temps in the 100F range on a hot day.....

Which is what I was saying prior. Its basically (centrifugal units) a turbo driven by a pulley. So while the percentage of power to drive will be slightly higher on a supercharger, the turbo has the potential to be the more efficient unit. When comparing equal CFM delivering potential.

I don't see why a turbo would be more efficient than a centrifugal. Both have very efficient maps. It comes down to parasitic loss, which is hard to quantify with a turbo (but its definitely there, although many people like to pretend there's a free lunch)

The efficiency isn't the problem with centrifugal superchargers....its their boost curve IMO

well one way a centrifugal SC isn't as efficient as a turbo is that it spins at such a low speed in comparison to a turbo....either the compressor blade design is different or they're operating well below their efficiency range. My turbo on 9psi is pulling about 40-50,000rpm, while a centrifugal at best is maybe in the 10-15,000rpm range

the bigger the compressor wheel, the less RPM for high efficiency.

I don't know what the RPM/gearing is on most centrifugals, but I would expect they make the speed match the efficiency ranges

I had a T25 that I spun to 200K RPM's. But was just as efficient at 80K RPM's. Thats a very small turbo though

well one way a centrifugal SC isn't as efficient as a turbo is that it spins at such a low speed in comparison to a turbo....either the compressor blade design is different or they're operating well below their efficiency range. My turbo on 9psi is pulling about 40-50,000rpm, while a centrifugal at best is maybe in the 10-15,000rpm range
Way off, while you are right that superchargers are directly tied to RPM as to what type of boost they are creating while they operate on a linear effect not being able to create max efficiency at a lower RPM like a turbo can however due to gearing a supercharger in many cases is spinning very close to the speed of your turbo. My unit is revolving at 43K+ times per minute when I am at 5700RPM's.

Edit- Here is the step up ratio gearing for most popular supercharger units used.

Internal Blower Ratio for blowers.
ATI P-600 3.05=1
ATI P1-SC 4.10=1
ATI D1-SC 4.10=1
ATI D1-SC 4.10=1
ATI D1-(all) 4.44=1
ATI F-(all) 5.10=1
Paxton SN 4.44=1
Paxton NOVI 3.54=1
Paxton GSS 4.40=1
Vortech V-1 3.45=1
Vortech V-2SQ 3.61=1
Powerdyne DB11 3.05=1

whats the usual external ratio range? IE, Pulley diameters

For most crank pulleys Vortech and Paxton use a 6 - 7 inch diameter and for the charger pulley they use a 3.25 - 4 inch. Ofcourse you can get other sizes if you are say using a unit that would be capable of making 20PSI you would get a larger charger pulley and a smaller crank pulley or do the opposite if you wanted to create max boost out of a smaller unit (assuming you didn't hit the max CFM/RPM rating of the unit)

So for anyone doing the math in my case:

It would be - 6 divided by 3.5 (my crank pulley being 6 inches and my supercharger pulley being 3.5)= 1.714 x 5700 (my RPM's) x 4.44 (my superchargers step up) = 43385

so roughly 2:1 on the pulleys, and the average internal was 4:1, call it 8:1 total ratio average. At 5K RPM's, thats 40K RPM's.

Would be a challenge to put something like that on a bike that revs to 16K RPM's :D

so roughly 2:1 on the pulleys, and the average internal was 4:1, call it 8:1 total ratio average. At 5K RPM's, thats 40K RPM's.

Would be a challenge to put something like that on a bike that revs to 16K RPM's :D
You would just use a smaller crank and a larger blower pulley to get close to a 2 or 3 to 1 ratio. I know my best friends car (a S2000) revs to like 10K and the paxton supercharger is a very popular mod with those guys.

i personally think you should super charge ur not gona b putting 20 lbs. of boost on ur engine. 6 lbs. is the highest u should go on stock internals. and im guessing that u want off throtle power if so then definately supercharge, turbo or supercharched u never get something for nothing turbos use energy from the exhaust witch restricts exhaust flow at the cost of a few less ponys, supercharger eat ponys off the crank. i dont see how that matters when you consider that ur trading a small amount of horsepower to add 100 + . i mean come on id happilly trade 5 dollars for 100. its youre car its all about ur personal preferance

please don't bring back threads over 3 months old.