Max. PSI

what is the maximum psi a 95 gsr can handle w/o messing with the engine internals. and what would i need to do to prepare my car for a turbo.

id say 6-8, safely, some say 10-11, but it all depends on the turbo your using.

anyhwere from 6-8 id say safely and reliably

yeah, due to the high compression, i have heard like anywhere from 6-10 psi

I would not want to run that daily though... 8 at the track might be ok, but the idea of high compression, a non-stock turbo'd car not engineered for boost.... I'd be wary about daily driving it. I honestly don't know how boost tough these lower ends are... also wondering about the valves, and interference, or valve float if too much boost.

how would i prepare my engine if i wanted to go higher, lets say 11-higher

I would say 5 psi daily, and around 8 and maybe 10 at the track but 10 may be pushing it.

in order to prepare it for more you would need to lower the compression. I guess to do a sloppy job you could just change the pistons and say the hell with it and run 10-12 at the track.

I would not want to run that daily though... 8 at the track might be ok, but the idea of high compression, a non-stock turbo'd car not engineered for boost.... I'd be wary about daily driving it. I honestly don't know how boost tough these lower ends are... also wondering about the valves, and interference, or valve float if too much boost.

im a noob at this, does that mean i can't drive it everyday?

No it means that driving and putting like 8 or 9 psi and driving it everyday puts a lot of stress on the engine.

Read up a little on turbos before you ask about how much psi you can run! There are many factors. I could run more psi on a smaller turbo and much just as much power on a larger turbo at a lesser psi.

With a good tune, id say a stock bottom end could hold 10-15 psi!( With a really GOOD tuner!)

I didn't think the size of the turbo had any relationship to how much power per psi it puts out.... Usually size only matters in spool time and max psi possible. each psi should still add a fixed amt of hp, based on compression. The size of the turbo relates to the size of the impaler, and the size of the housing, which relates to the spool time, and possible boost. Please correct me if I'm wrong.

search.

can i upgrade my engine to be able to handle more psi daily.

I didn't think the size of the turbo had any relationship to how much power per psi it puts out.... Usually size only matters in spool time and max psi possible. each psi should still add a fixed amt of hp, based on compression. The size of the turbo relates to the size of the impaler, and the size of the housing, which relates to the spool time, and possible boost. Please correct me if I'm wrong.

you're correct when you say the turbo realtes to the spool time and possible boost(sort of) but, the size of the turbo has quite a bit to do with how much hp per psi it puts out. take a 15g stock turbo off of a talon tsi, and take a shiny new garrett t3/to4e and stick them on the same car, you'll find that you're making approx the same hp at 7 psi from the garrett turbo as you are at 10-12 psi from the talon turbo.

it's prettymuch got to do with how much air (cfm) the turbo can flow efficiently... where you'll get a slightly quicker spool up from the tsi turbo, the garrett is much more efficient, and will flow more air per psi. psi is prettymuch a useless number without knowing the volume of air the turbo is capable of (cfm)

now when it comes to max psi the turbo can produce efficiently, you'll find the numbers on most turbochargers are much higher than most engines can handle without some serious building.

can i upgrade my engine to be able to handle more psi daily.

yes but it usually requires messing with the internals... i wouldn't go over 15 psi without getting the block sleeved, rods/pistons usually top out around 10 on the gsr... compression is too high for boosting really, but if you get the right tune, you can make massive amounts of power running high comp and boost.

if you're really thinking about getting serious with it i highly recommend a good engine management system... the ones i can remember are hondata and the aem EMS... i'm sure there's new cheaper options out there, i just haven't been looking for a year or so...

Ah, thank you deleriousZ. What you said makes perfect sense. cfm (cubic feet per minute) would really matter on the efficiency of the turbo. I imagine stock turbo's are not the best at being efficient, but aftermarket like Garrett would have put some research into it. My friend's Saab 9000 CD has a garrett t25 which seems to put out some nice numbers. He can run about 24 psi on the thing before it runs outta steam. It does outrun the fuel supply and somewhat drops off to about 18 at redline (5.5k). He mentioned something about an arc number that was supposed to be the ratio of the impaler to the housing, and said it affected spool time, and displacement of the boost. Thanks for clarifying that Z.

my pleasure, i'm here to inform :)

Ah, thank you deleriousZ. What you said makes perfect sense. cfm (cubic feet per minute) would really matter on the efficiency of the turbo. I imagine stock turbo's are not the best at being efficient, but aftermarket like Garrett would have put some research into it. My friend's Saab 9000 CD has a garrett t25 which seems to put out some nice numbers. He can run about 24 psi on the thing before it runs outta steam. It does outrun the fuel supply and somewhat drops off to about 18 at redline (5.5k). He mentioned something about an arc number that was supposed to be the ratio of the impaler to the housing, and said it affected spool time, and displacement of the boost. Thanks for clarifying that Z.

Your friend is crazy! If he is using the Garrett T25 which comes in all 2g dsm (eclipse/talons) stock than he is boosting too much! Tell him that turbo is gonna die out pretty quick. Stock T25's only can handle 16psi and run out of breath around 6k rpm. He is only burning out his turbo even though he does push out 24psi, expect him to replace it soon. And for you people who wanna know how much boost u wanna run id say:
5-6 Daily driving
7-8 streetracing
9-10 lower compression
11-13 professional modified engine.

you're correct when you say the turbo realtes to the spool time and possible boost(sort of) but, the size of the turbo has quite a bit to do with how much hp per psi it puts out. take a 15g stock turbo off of a talon tsi, and take a shiny new garrett t3/to4e and stick them on the same car, you'll find that you're making approx the same hp at 7 psi from the garrett turbo as you are at 10-12 psi from the talon turbo.

it's prettymuch got to do with how much air (cfm) the turbo can flow efficiently... where you'll get a slightly quicker spool up from the tsi turbo, the garrett is much more efficient, and will flow more air per psi. psi is prettymuch a useless number without knowing the volume of air the turbo is capable of (cfm)

now when it comes to max psi the turbo can produce efficiently, you'll find the numbers on most turbochargers are much higher than most engines can handle without some serious building.


Umh....psi is psi. Pressure per Square Inch.No matter what turbo you are using, its the actual PSI making the added power.Think about it. The more PSI`, the more power. So 10 Psi from from the Talon is the exact same pressure from the Garret. Just the talon turbo may be more efficient, or take less time to spool.A bigger turbo will let you add more PSI, say upt to 25 PSI compared to the smaller which could be 15 PSI.

Umh....psi is psi. Pressure per Square Inch.No matter what turbo you are using, its the actual PSI making the added power.Think about it. The more PSI`, the more power. So 10 Psi from from the Talon is the exact same pressure from the Garret. Just the talon turbo may be more efficient, or take less time to spool.A bigger turbo will let you add more PSI, say upt to 25 PSI compared to the smaller which could be 15 PSI.

psi means nothing(in an automobile turbocharging system) without a cfm(or whatever other system of measurement) number... it's all about airflow. think about it this way... the more air, the more fuel can be added to make more power... now take say a garden hose, you put enough water through it so a pressure guage reads 10 psi at the end of the hose... now take a fire hose and do the same thing... it's still 10 psi, but you'll be getting anywhere between 4 to 6 times more water (not the actual number just a guess) take that and apply it to a turbocharging system where the talon turbo is the garden hose and a garret t3/t04 is the firehose..

i suggest you do a little more research before giving people advice:)

The GSR's modest 10:1 compression has no bearing on how much boost you can run. If you can run 15-16 pounds of boost on a forged 10:1 motor without detonating you could run 15-16 pounds of boost on your stock 10:1 motor without detonating.

8-10 pounds with a great tuner is perfectly acceptable on a stock GSR motor. 5-6 pounds? Please. Stock drag kits with an FMU with run forever at 7 psi.

Your friend is crazy! If he is using the Garrett T25 which comes in all 2g dsm (eclipse/talons) stock than he is boosting too much! Tell him that turbo is gonna die out pretty quick. Stock T25's only can handle 16psi and run out of breath around 6k rpm. He is only burning out his turbo even though he does push out 24psi, expect him to replace it soon.

It may be slightly different from the eclipse turbo, it's a garret T25 M.... whatever the m means, it's a lot larger than the turbo's I've seen on my other friend's 2nd gen GST. I will ask him exactly what it is, but he's refered to profession tuning companies (for Saab) like abbot racing, and swedish dynamics, and it is perfectly fine to run 20 or so psi on the stock turbo. He doesn't care if it lasts much longer anyway, he's upgrading to a larger size.. not sure but I think td04 or something like that. Thanks for the advice though.

psi means nothing(in an automobile turbocharging system) without a cfm(or whatever other system of measurement) number... it's all about airflow.

Actually...psi is what moves the air from the turbo to the combustion chamber. the pressure forces the air into the combustion chamber because there is less pressure in there. if you are running at 0 psi with X amount of airflow, none of it will go into the combustion chamber. there's like an equlibrium. i dunno how to really describe it better, but i used to work at an engineering company and i would work on oxygen concentrators (which are all about psi and flow).

Actually...psi is what moves the air from the turbo to the combustion chamber. the pressure forces the air into the combustion chamber because there is less pressure in there. if you are running at 0 psi with X amount of airflow, none of it will go into the combustion chamber. there's like an equlibrium. i dunno how to really describe it better, but i used to work at an engineering company and i would work on oxygen concentrators (which are all about psi and flow).

ah yes, but you see, psi is directly dependant on cfm for making boost... true, you can be flowing cfm without boost (otherwise n/a engines wouldn't work) but it's physically impossible to have pressure in a flowing cylinder without some amount of air flowing through it.... if it were a closed cylinder, yeah no problem... but since everything is moving, there needs to be air to move...? lol

i'm not saying psi doesn't matter when you're applying boost, because that'd be totally out to lunch, i'm saying in order to have pressure (measured in psi) in an open ended enclosed area (charge piping) you need a cirtain amount of air flowing through that area... when the throttle plate closes and blocks off the airflow, that's when you can develop static pressure, but in the real world without some sort of air relief valve the pressure slams back into the compressor.

now if you had 2 throttle plates along the length of the pipe and was somehow able to shut them at the exact time with no leaking, you (in theory) would have a static 10 psi, with no airflow.

i really don't know where i'm going with this... it's really late and i've been drinking...

bud to run a high comp motor with high boost make sure you got a good tuner and a deep pocket did some research and man it does put strees on the pocket. your gonna have to build that motor like no one has b4. The power is yours my friend!