Holset HX35 vs HX40klkl

[dsm-onster]

There's nothing wrong with a 3inch O2 housing, IMHO. Looking at how a turbo functions, you want as little restriction post turbine as possible. You can port your BEP housing to match the 3" outlet. Or not worry about it. A step out is alot better than a step in. There is a little turbulance, but nothing that will ruin your chances of reaching your goal by any means.

 

[jrohner]

Why are you so concerned about how much boost it will take to make a certain amount of power? Boost pressure doesn't really relate from one size turbo to the next. Example: a 16G at 21 psi isn't 'harder' on an engine nor does it create more cylinder pressure than a 50 trim at 18 (well it depends on the tune for each, but you get the idea I hope). The hx35 at 30 psi isn't going to wreck your engine vs the hx40 at 25 'saving' your engine or headgasket. You could wreck your headgasket at 16 psi on a 14b with a crappy tune, and have no trouble with the same gasket at 30 psi on an hx35 with a good tune. Do you think a 16g turboed engine with 400hp is going to blowup vs a 500hp ('low boost') hx40 turboed engine running 100,000 miles? I'd bet on the 400hp 16g car lasting longer even if it took 1.5 times as much boost.

 

[turboglenn]

Why are you so concerned about how much boost it will take to make a certain amount of power? Boost pressure doesn't really relate from one size turbo to the next. Example: a 16G at 21 psi isn't 'harder' on an engine nor does it create more cylinder pressure than a 50 trim at 18 (well it depends on the tune for each, but you get the idea I hope). The hx35 at 30 psi isn't going to wreck your engine vs the hx40 at 25 'saving' your engine or headgasket. You could wreck your headgasket at 16 psi on a 14b with a crappy tune, and have no trouble with the same gasket at 30 psi on an hx35 with a good tune. Do you think a 16g turboed engine with 400hp is going to blowup vs a 500hp ('low boost') hx40 turboed engine running 100,000 miles? I'd bet on the 400hp 16g car lasting longer even if it took 1.5 times as much boost.

very well said. I wasn't able to find a way to put it so politely so i just didn't say anything.

after being told how the correct things i know didn't matter or apply to him i just figured i'd wait for the post about beign dissapointed in the car's performance on the few days it does go out to play. Would be a shame to spend money on a large turbo to get spanked by a 20g car on the street or track becasue of lacking the fundamental undersanding of what you're really doing when using a turbo to gain power from your motor and what boost really means besides it's reading in PSI on the guage .

It doesn't matter what a turbo can flow at a given pressure level because if things aren't done correctly you could be at 25 psi and only letting enough air go through and get burnt properly to create 250hp on a turbo that should be good for over 450 and then watch as the 14b car on 19psi goes sailing past because he took the time to listen and understand the information that was so freely given to them

 

[xxShaneOmac]

What stretches Head Studs?

Oh thats right its PSI, The more PSI the better chance of stretching your stock Head Studs.

And what happens if you stretch your stock head stud's?

Oh again, your head gasket goes.



So If I could have 400whp on a T25 Pushing 500psi vs 400whp on a HX40 at 22psi on MY setup rightnow,

Im going to go with the HX40 beacuse I have stock head stud's and I do not want to stretch them.




I dont know how so many people thought I was thinking PSI blows head gasksets, No.

PSI is the gateway drug to blowing your headgasket by stretching your stock head studs.


Heat and knock blows Head gasksets, thats all in the health / tune of the car, I understand that.

 

[dsm-onster]

No. As I already mentioned in this thread, cylinder pressure stretches head bolts (dsm have head bolts not studs, stock). 500whp is 500whp. It takes the same cylinder pressure for an hx35 setup to make 500whp as an hx40 powered car. Knock generates abnormally enormous cylinder pressure. This is why knock lifts a head.

Yes, you can get more cylinder pressure by raising the boost. But just to match the cylinder pressure of an hx40 at say 22psi, you'll need your hx35 to be pushing 30+ psi (hypothetical numbers). MEP stretches headbolts. Not boost. Bolts/stud are said to handle a certain horsepower, NOT boost.

jrohner is exactly right. An hx40 setup at 22psi which yields 500whp is going to put alot more stress on the headbolts than that same setup with an hx35 at the same 22psi.

 

[jrohner]

The boost PSI number is coming from your intake manifold, not your cylinders. I think you are confusing your head gasket with your intake manifold gasket.