engine stress, psi vs hp
03-18-2011, 12:26 PM
#1
Member
Thread Starter
Join Date: Mar 2003
Location: Alabama
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Vehicle: 04 Tib GT V6 Turbo
engine stress, psi vs hp
First i will explain my situation. I am thinking of a turbo upgrade because I want more power on pump gas. But I was thinking about it and i am only at about 50% the full potential of my current setup. Usually i drive with the boost controller off to save gas and only turn the boost on when im going to race. So i was thinking of going water meth instead but i dont want to unnecessarily hurt the longevity of the engine. So this may be a total newb question but here it is. Would there be any more stress on the engine with say a 400whp gt28rs@28psi with race gas/water meth setup than a 400whp gt35r@17psi pump gas setup so long as all things like heat and detonation were equal. Even if both these turbos are capable of more or less than stated hp/psi what im basically asking is does more psi put more stress on the engine or does 400hp equal the same stress no matter what boost level or turbo you're running.
03-18-2011, 02:25 PM
#3
Senior Member
Join Date: Feb 2010
Location: Kent, Wa
Posts: 1,468
Likes: 0
Received 0 Likes
on
0 Posts
Vehicle: 13 Gen Coupe Ult.
The Horsepower is the stress factor here. Psi means nothing, your are putting the same amount of force to the Intake manifold, it just takes more boost from the smaller turbo because of the lower CFM.
All in all, 400Whp is a pretty general goal for people here lately. I am very close to that off alot smaller ALOT cheaper turbo, a Garrett 50 trim, with a .48 Ar housing.
I still have a few PSI left in her, right now i am at 21 Psi, and havent made any Dyno pulls, but is super smooth, my last pulls were 17Psi and 380WHP. So you do the math 10 hp gain per Psi should net me my goals, should be right around 420Whp.
All in all, 400Whp is a pretty general goal for people here lately. I am very close to that off alot smaller ALOT cheaper turbo, a Garrett 50 trim, with a .48 Ar housing.
I still have a few PSI left in her, right now i am at 21 Psi, and havent made any Dyno pulls, but is super smooth, my last pulls were 17Psi and 380WHP. So you do the math 10 hp gain per Psi should net me my goals, should be right around 420Whp.
04-29-2012, 10:16 PM
#8
Senior Member
Join Date: Feb 2009
Location: Boston
Posts: 1,932
Likes: 0
Received 0 Likes
on
0 Posts
Vehicle: 2006 Pontiac GTO
How do you figure both 28psi and 17psi would net the same 400whp? On a given engine/head/cam/intake setup, X psi is X psi. Despite what everyone says, there's a direct relation between boost and volume of air going into the engine regardless of how you create that boost (volume of air going in = boost pressure ratio * engine size * rpm/2 * volumetric efficiency). Of course, a smaller turbo will be less efficient and add more heat (so the same volume of air will be less dense), and also choke the exhaust more, but probably not to the extent that you'd need 11 more psi to make up for it..
for a given power level, meth would be safer because it would decrease the chance of detonation by cooling the charge and increasing octane. Plus the cooling effect along with the fact that it allows you to safely run more aggressive timing will yield more power. Detonation aside, the stress should be the same for a power level. But detonation should be your main concern at those boost levels. 100% meth works best, works well with pump gas too. Shouldn't hurt the engine in any way, it gets vaporized instantly. Needs to be properly tuned though.
for a given power level, meth would be safer because it would decrease the chance of detonation by cooling the charge and increasing octane. Plus the cooling effect along with the fact that it allows you to safely run more aggressive timing will yield more power. Detonation aside, the stress should be the same for a power level. But detonation should be your main concern at those boost levels. 100% meth works best, works well with pump gas too. Shouldn't hurt the engine in any way, it gets vaporized instantly. Needs to be properly tuned though.