Great thread. I am unfortunately (for my car) in CA and am subjected to 91 CrAptane fuel. I will be exploring this area and hopefully have something constructive to add to this thread. I have an Aquamist HSF-6 kit that I haven't yet installed...still trying to decide!?

 

Decide what?

 

Decide whether or not I want to install the kit. I know it's best for safety and some extra power given that I live in CA, but the way that I use my car, it may not make sense (drive to work, sometimes take weekend trips, etc...)

 

If you never boost the car, you will never use any Meth. When the opportunity arrives that you can boost the car, you will reap the benefits of the meth.

 

Not sure i'm following here... Heads and cams allow for easier breathing and better flow - how exactly is that allowing for higher boost?? If anything I believe that this would mean you want to run LOWER boost since so much more of the air is getting into the engine rather than backing up in the intake manifold and registering on the gauge. You sure you've not got that backwards? I know, having done it, that when you free the intake and heads up that the airflow goes up and boost reading goes down if shaft speeds stay the same. Hard as heck to see this with a turbo since the W/G are boost referenced but if you add heads and intake work to a vehicle with a pulley driven blower (and no other changes) you will see boost go DOWN even though the blower spins just as hard. This is why I stated that comparing boost levels really isn't a great way to go unless both cars in question are pretty much the same. Once you go into the heads and swap cams comparisons get out of whack fast...

 

Yep, Dennis is correct, I am personally running 1.3bar on my UMW 2C (K24/26's) on 91craptane, I dynod 424hp/460tq on a DynoDynamics aka "heart breaker" last week, using a 1.41 conversion for dynojet gives 520hp/564tq to the wheels uncorrected at 6220' altitude. Of course, with minimal air going through the IC's there was probably quite a bit of timing being pulled as well.

 

LOL...now I'm confused!

I totally get what you are saying about reducing air restriction to make the same power at a lower boost level, however...

...on my old car, with stock internals, I could only run 1.2 BAR on K24/18G's safely on 100 octane without the knock sensors kicking in. After I built my motor (modified heads and cams), I was able to run 1.5 BAR on 100 octane all day long with GT35's without the bumping into the knock sensors.

With the heads, cams and GT35s...I had a LOT more airflow through the motor, but also from the much larger turbos. But, I was able to run mjuch higher boost on the same octane, and make a ton more power.

 

Swapping the turbos may have been key. Smaller less efficient turbos will have higher exhaust backpressure and hurt airflow. It's possible that the turbos were both more efficient at compressing the air (not as hot) and that the exhaust side also flowed better. that said, yeah I'm a little confused by that too! Did compression change? Piston design or chamber design? More overlap in the new cams perhaps? Hrm, were the knock sensors removed during the build - maybe they got torqued differently?

 

The car was running stock pistons, pauter rods, different valves and springs, modified stock cams, modified stock headers and ported/polished stock head. Knock sensors were still in place and still worked (ask me how I know... )

Strange...

 

I think there is a lot to be said about big turbos in terms of flow, reduced intake temperatures and reduced back pressure (all equtes to less heat).

That said, for a street car not trying to set standing mile, 60-130 times, etc... the smallest turbos for your desired horsepower will give you the most driveability and throttle response.

I don't tghink anyone has really answered the OPs question. I think the answer is 575-600 crank HP give or take. EDIT 650 crank

 

Your comment about the smallest turbo is one that I think many overlook. I fell for this on my last car when I ran a 71mm turbo capable of making well over 800RWHP but was limited to around 600RWHP on pump gas. The power ended up peaky with little power being made until I spooled. It was fun for sure and put down great numbers but for daily street driving it was too much for a stick shift. I was in the process of moving to a MUCH smaller turbo, fully intending to make at least as good power numbers on pump, when that car was murdered. I still believe it would have been much more fun and even faster on pump gas with the better power curve...

 

A28's FTW! I think that they make amazing sense for a stock motored, street car that wants to run fast but mostly wants to be "driven"...(to me that is canyons, track, around town aggressively). For highway rolls and peak HP numbers, I'd go 30's or bigger FTW.

TTBoost-good point on the meth but the problem is that I boost the car almost all of the time when I drive her... I don't beat on her but I definitely use the turbos!

I'll share some numbers on pump once Tony and I get the tune all worked out (I'm still breaking in the new clutch and motor)...

 

My boost raised from 1.1 to 1.4 when i went from a stock exhaust to the JIC w/200 cel cats. I had to lower the boost back down to 1.1 - 1.2.

 

sounds like an EBC, which means you overrode the ecu safety, on your stock file you might have seen a slightly higher peak, but not that high.

 

Revo does not allow you to set an exact PSI/BAR setting. It has its own value settings (1-9) and they represent changes in the ECU. I had the boost set at 8 and that, in turn, allowed the motor to be boosted to 1.1 bar with the stock exhaust. Once I changed the exhaust, to a less restricted model, the actual boost raised to 1.4 bar so I had to lower the value to 7 (or 1.2 bar).