8psi is going to fill the fixed volume of the intake tract no matter what volume of air your turbo is capable of producing. that's efficiency, not power. that has more to do with how quick the turbo spools and how much total air it's capable of moving than the output of the engine at any particular boost pressure.

once you set the wastegate that's a set amount of pressure in your manifold for the engine to use. if you were trying to compare two turbos to see which is "better" you would need to fill a vacuum with each and measure how long it took to fill said vacuum to XX pressure. that's obviously going to be shorter on the bigger compressor wheel. same thing with spool up, how much exhaust pressure do you need to have it at peak efficiency?

it's not the boost pressure that is the difference between two compressor wheels, it's the time it takes to reach that pressure and what conditions the turbo itself has to meet. if you are exceeding the efficiency of a turbo then yes, a bigger turbo will produce more consistent pressure and therefor probably more power. if you are pushing the limits of one compressor and not the other you aren't really comparing apples to apples anymore, are you? set your wastegate to 8psi and it's the same 8psi you get from any turbo out there, just with a different spool up RPM and time to full boost. it changes the power curve, not the peak output at full boost.

EDIT: to answer directly, the extra volume of air you are pushing with the larger compressor is going straight out the wastegate.

 

i definately have to agree with dan on this one.....any other input?

 

Pressure and volume are the same thing when your talking about boost, all other things equal, at 8psi the volume of air being put into the actual piston chamber will remain the same regardless of the turbo. As Dan said the extra volume of air will be blown off through the wastegate. 8psi is 8psi regardless of how it's made.

 

I do agree that 8 psi is 8psi, but what I'm saying is different setups and different turbos will show different power. Maybe I said it wrong. My bad, but guys are talking about different turbos, so it would depend on the rest of the setup. I'll tell you what. You put the RRM kit against mine at 8 psi both and we'll see. That's what I was saying. If we're talking about RRM kit only, fine. But for custom it's up in the air.

 

Turbos are all different, and I completely agree with you.But, all other things equal, 8psi should put out the same peak hp no matter what (with some exceptions). Obviously, the time needed to spool the turbo up is going to make a difference in the curve, but peak numbers should be very similar. But, when you start changing other factors, such as the tubing, the manifold, the ic, and many other factors you will see differences in numbers.

 

I agree 100% that different setups will net different power. that's not what was said, as I quoted before:

which is just plain ol' silly.

 

how about converting it to ounce instead of pounds? Man the RRM kit puts out 112 OZ's of boost!!!! thats a lot, way more than 7 pounds....

 

I said it wrong. What I meant to say is that the RRM kit is putting this amount of power with a 16G and a custom setup with a T3T4 is putting that much out. As far as I understood talking to people is that the bigger turbo will give you more power with less.

 

And another thing. Are you telling me that i/c piping diameter is making such a difference that the RRM kit is putting out 245 CRANK horse power at 7 psi, and I put that much at the wheels with the same boost. Well then, RRM did a poor job with theirs. Just for clarification I am talking about Dynojet.

 

everything makes a difference. you have four larger injectors, different intake location, different piggyback. the intake location alone can account for a good deal of HP, especially on a dyno, because it will pull much cooler air than if it were over the tranny. the exhaust manifold has some differences too, if I'm not mistaken. the larger injectors, rather than the one fifth injector, will allow for an even distribution of fuel that will allow for much more power when tuned.

lot's of things make a difference, and the power relies on everything. a tubular style manifold with equal length runners is supposed to create more tourque sooner than the short, uneven runner manifold you have. the larger the diameter of pre-compressor intake and the size and location of the intake filter itself make a large difference; the filter becomes a form of resistance if it is too small, or air can't get to it very easy if there is no clearance around it. the further away from the egine the better, because no intercooler system is 100% efficient.

have you dynoed your car yet to see what it's putting down? I honestly don't remember. I really wish I thought I should put the turbo on the car, but things have changed so much since I bought the RA

 

No I didn't dyno it yet, but if I have only 215 whp I'll cry.lol And to get back to the topic, isn't Thunder Rush running 10 psi for two years without a problem? Is there any one else with more?

 

Chowetime is running 12psi, I think she was wanting to go higher yeah, thunder-rush wasn't modifying timing either last I knew of. over 300whp.

 

Chowtime hasn't been on for a while. I wonder if she has any dyno numbers. I sure would like to see that. But the PR guys give me hope for some serious power. I'm planning to put a 3" exhaust and raise the boost to 10psi this summer.

 

be aware of what you read, RRM claims they got 245, that's not WHP maybe crank hp, and to top it off they were running on RACE GAS, not pumped gas so the octacne level will affect the outcome of the HP as well so it's easy to fool people into thinking that they get big number, but if you knew all the facts then you would think otherwise

 

^^ dyno was ran on both pump gas and 91 octane