engine mods for turbo or supercharger

[beef_bourito]

hey, what kind of engine mods would i need to do to support a turbocharger or supercharger at very high boost (i know about high octane fuel) to prevent the engine from knocking, detonation, and it going boom.

Thank you

[Sluttypatton]

The most important modifications directly needed to support any turbocharged vehicle are related to fuel and ignition, even more so for a high boost one. The first and foremost concerns being intercooling, a/f ratio, and ignition. If the motor isn't properly tuned, it won't matter how strong your internals are, they won't last long. The charge air must be properly intercooled, this is not optional. Modifications to the fuel delivery relies greatly on the boost level and vehicle, and could vary from piggyback controller to standalone engine management, but in general rising rate fuel pressure regulators won't cut it for medium to high boost applications. Fuel injectors and fuel pumps will generally require consideration, unless your vehicle came with a high flowing fuel system. Ignition should be upgraded, and timing should be adjusted unless you have a knock sensor equipped vehicle, in which case the timing will be controlled by your ecu (unless you've replaced it with a standalone system).

Other important considerations are the cooling system, exhaust, and engine internals. Many stock cooling systems could be overloaded by a high boost application, that would be bad. Ideally the exhaust system would be as non restrictive as possible, technically you don't even need one after the turbocharger, just a straight pipe out to the back (legally may be a different story).

One would also be wise to take the engine internals under consideration when building a high boost motor, but again, it depends on what motor you started off with and how high the boost is...not all engines were created equal, and some may be just fine left alone. As a rule make sure the motor is in good shape, that is the absolute minimum requirement, and I have heard of some well tuned high boost motors lasting quite long with stock internals...but the key word is well tuned. Basically, make sure all of the internals can handle the added heat and stress. What you actually need to beef up is completely up to your discretion, and depends on how wild the boost is going to be.

Getting the HP to the ground reliably is a whole other story.
I'm sure I'm overlooking some stuff since this is such a huge subject, but I'm sure somebody will come and add in anything I may have missed.

[matt11583]

if you have a big turbocharger on it you need a few different mods. an intercooler is a must. the air has to be cold. you must also have a big enough exhause to get all the forced air out of the engine. you must also have a good fuel system to keep the air/fuel mixture balenced. a upgraded chip may be required also. you must have a better ignition to spark all the extra fuel. as far as teh internal mods go, like sluttypatton said, some engines can handle the higher boost and others cant. it depends on what car you have. in most cases a good stroker kit will be a good choice. cams can help get more out of the turbo but in most cases arent needed.
if it is a big turbo that added a lot of power to the engine, you may want ot look for some suspension upgrades in the future but the stock suspension should work for a while.

[97Tsi]

Originally Posted by Sluttypatton

One would also be wise to take the engine internals under consideration when building a high boost motor, but again, it depends on what motor you started off with and how high the boost is...not all engines were created equal, and some may be just fine left alone.

Okay...I'll throw out an example. Where would you start with a stock 4g63(eclipse gst motor)?

[Sluttypatton]

Keep in mind while reading this that I have no experience with DSM's or the 4G63, all of my post is just an educated guess based on what I have heard about the 4G63.

Depending on how extreme the boost level gets this motor might be fine stock. The 4G63 has a reputation of being tough, and quite happy breathing as much atmosphere as you can ram down it's throat. The oil squirters that help facilitate cooling of the pistons greatly improve the likelyhood that the stock pistons will be adequate, and the lower compression ratio (7.8:1) on the 1G's will help to avoid detonation. I'm sure that this path has been well treaded by DSM owners, so the search engine is your friend, learn from others mistakes and get some guidlines to start from. I have been told that the combustion chamber on the 4G63 is quite well designed and effectively helps control detonation, so careful thought might be inline if you were to decide to cut the compression ratio, it would be a pity to ruin the effectiveness of it. This may be a motor that would survive with minimal modification to the internals, but this is just a guess based on what I have heard and the motor's reputation. Searching through some DSM forums, people have reported some pretty high boost levels on stock motors with decent longevity, however this is the internet and one should always question the information on it.

All of this is assuming that the fuel and ignition has been properly modified and tuned, and the charge air is well intercooled.

[97Tsi]

Thanks for the info, I'm sure it will most likely come in handy in the future...

[justav6]

Originally Posted by beef_bourito

hey, what kind of engine mods would i need to do to support a turbocharger or supercharger at very high boost (i know about high octane fuel) to prevent the engine from knocking, detonation, and it going boom.

Thank you

i really dont know about the other information given by others, but i would have to disagree. the only cars i work on have turbos, and im gonna give you my pieces of info. intercooling is absolutely not needed, but is recomended. intercooling is more efficiant than hot air. all grand national for example pre 86 were not interooled.all intercooling does is makes the air more dense which actually makes the a/f leaner. anyone that upgrades their intercooler turns up their fuel pressure. a few things that are required especially under high boost applications are as follows. manifold absolute pressure sensor (map) and lines. forged or hypernetic pistons, and rods. free fowing exaust, but not too large of headers. croosover pipe. new ecm. larger fuel pump and injectors are always recomended when turbocharging (although iv never heard of anyone not going larger, certainly not with high boost.) adjustable fuel pressure regulator. highly recomended, but not always needed> external oil cooler. neoprene head gasket. k+n type air filter. the added hp will wear everything quicker, specificly trans ( clutch if manual). there will be some other thing you will need such as plumbing but those are the most important/expensive.

[Sluttypatton]

Intercooling IS absolutely necessary, if the charge air is not intercooled at high boost it is very unlikely that you will be able to control your detonation. Air gets very hot when compressed, and in anything other than low boost applications it is simply unacceptable to not intercool the charge air, since otherwise it will severely promote detonation. That is what intercoolers are for...cooling, the increased density is just a plus as a result of the colder charge, and I don't see why anyone wouldn't want that since a denser charge means more power.

Forged pistons and rods are NOT necessary, the only reason they would be is if you were planning on building a high revving motor or the combustion temperatures were wild. Granted, sometimes they are required, but the real key to a motors survival is tuning, not forged pistons...even a forged piston won't survive detonation for very long. The main stresses on a connecting rod are the tensile and compressive loads induced by the inertia of a piston at high RPM, the power load is less significant, clearly new rods are not always needed. Doubling a motors power output will not double the power load, however tensile and compressive load due to RPM increase exponentially proportionate to engine speed, meaning they get very high very quickly. So if you were to triple the engines speed the inertial loads the rods are subjected to will be nine times as great. Doubling the power output would maybe increase the power load by 20%.

A free flowing exhaust is an understatement, after the turbocharger you don't even need one. This would be ideal since the turbine is partly driven by the pressure differential between the two sides of the turbine. I would personally run a straight pipe out the back.

A new ECM is not required, since you will be supplementing fuel supply with a piggyback fuel controller, and ignition can be controlled with some sort of MSD unit, or left to it's own devices if knock sensor equipped.

Larger injectors and fuel pump may also not be required, they are only required when the stock ones are insufficient to support a proper air fuel ratio. Sometimes stock ones will be just fine for lower boost levels.

No one uses adjustable FPR's when turbocharging a naturally aspirated vehicle, they use rising rate FPR's, and those are completely inadequate for high boost levels, one must at least use a piggyback fuel controller.

An external oil cooler would be the last thing on the list of necessary things, again this is only necessary if the oil temperature is very high, overcooling of the oil can actually increase wear on the engine.

Headgaskets rarely blow due to boost pressure, and are by no means a weak link in the combustion chamber, when they do fail it is more likely the result of detonation. If one were to encounter problems with headgaskets blowing the best choice would be one with a built in wire that surrounds the circumference of the cylinder and creates a mechanical barrier against blown headgaskets.

[97Tsi]

Are you a mechanic of some sort sluttypatton, because i gotta hand it to you....you sure know your shit!

[Sluttypatton]

I am just an enthusiast that trys to be as educated as possible, however I will be starting towards my undergraduate degree in engineering sometime next year. I am by no means an expert, and there are definately more qualified people on this forum than me. I'm just a enthusiast that spends a lot of time in my shop, and a lot of time learning about everything I can. That is why I spend so much time in these forums, these forums are full of information.

I always try to ensure the information I post is correct, but sometimes I make mistakes, so don't assume everything I say is absolutely correct. I don't pretend to be an expert, so if something I say sounds fishy, double check it...I could be wrong.

[justav6]

some people i would consider experts are ken duttweiller (7.28@180) single turbo. kenne bell (also in the 7's) steve hurst(8's). these are all the sources of info i posted. i suggest you get your self the power pack book. there is tons on info from all the leading turbocharger experts. there is not much iv read on here that agrees with what they say.you can find it at www.kirbanperformance.com for under 20$. i would really like to know where you got this info from. yes you do want to intercool.straight pipes are not street legal, and very obvious by ear straight from a turbo. regular pistons cant hold up to high boost, which is why no high boost cars use them (buick gn, 89 turbo trans am, typhoon, syclone etc.) head gaskets are the first to go from excess boost. iv never heard of a stock injecto that is adaquate for high boost. what nonturbo car comes with 36psi injectors or higher? im not gonna say take it from me, but you should definately get your facts straight before you kill your car.

[Sluttypatton]

Granted many of these items are necessary in high boost applications, but lets be honest, you weren't only talking about high boost applications, you were making sweeping statements pertaining to all turbocharged vehicles (low boost or high). This is clearly illustrated by the quote:

a few things that are required especially under high boost

By saying "especially" you insinuate that it is required under low boost as well...this is misleading. You also say:

intercooling is absolutely not needed, but is recomended. intercooling is more efficiant than hot air. all grand national for example pre 86 were not interooled

I believe that the factory boost setting was 8-9 psi, clearly not making this a high boost vehicle. There are more examples of you referring to your list of required modifications pertaining to low boost applications as well, but I think two is enough.

So I stand by my post, however, if you were only talking about high boost vehicles I would tend to agree with you on more points. However, it is my opinion that turbocharged vehicles should always be intercooled, and in some cases a well designed stock piston, with a thick upper ring land area and good heat escape routes, may be adequate and have a decent life span even under high boost. I agree that depending on how high we are talking about, forged pistons may be required, but the lack of clairity in your post was misleading, indicating they were always necessary. The head gasket is not usually affected by higher boost levels, as I said before, it is usually detonation that will damage them. In these cases it is more prudent to deal with your detonation issue than beefing up the headgasket.