riceball777

I have the itch for more power. Please recommend me a turbo.
I have a stock f20c s2000 with a old school garrett ball bearing t3 50 trim .63ar turbo. It makes dynode at 395whp on 91 octane and 501whp on e85
The car is street driven everyday 15,000+ miles a year. The car runs 91 octane 95% of the time. Bottom end, mid range and over all fast spool is very important.

My car on e85 making 500whp is pleanty fast but with the rare e85 stations and the face that I drive so much I simply cannot run e85 the majority of the time. My car on 91 octane is not fast enough and leave something to be desired. I would love to make 450-whp whp on 91 octane by just swaping out turbos and keeping the engine 100%stock.

I was orgionally thinking about the gtx3076r(.63ar) but then people started saying the new gtx3576r was a better match? what other options do I have?

Muckman

iTrader: (2)

Swapping turbos wont help you make more power on pump gas. The turbo was never the limiting factor. The fuel was.

TheShodan

iTrader: (14)

You're interpreting the idea of "mismatch" wrong from an out of context quote from the Evolution forums.

For 91 octane that's tough. I had one person use The Wolverine on the S2000 w/ 91 octane, and seems happy with it so far. But the GTX3576R might be a bit better as either way, you need about 60lbs/min to get what you need and at least something with a 68mm or 71mm turbine wheel to make it work. Not everything will be responsive on either platform, as you're using such low pressure out of its efficiency range to try to make the peak power you want.

turbociv910

quick spool more power pick one

riceball777

. I know I need a bigger turbo for my goals. I'm willing to spend the money on a expensive ball bearing billet wheel turbo to help with spool and transit/boost response.

I want the fastest and best spool possible for my high power goals.

TheShodan

iTrader: (14)

I know, but it won't happen with low boost pressure (being on 91 octane) on a big turbo capable of 450whp on pump gas. Have you thought of meth/water? Much better alternative.

riceball777

What do u mean? But going to a bigger/billet wheel ball bearing turbo I should make more peak power on both pump/race and e85 fuel with the expense of slower spool and bottom end power.

For example I have an evo8 which i have had 3 different turbo setups. With the stock turbo I made 315whp on 91 octane. With a gt3076r I made 360whp on 91octane. With a billet wheel htagt3582r I made 420whp on 91 octane. Each turbo I gained top end power at the expense of bottom end power.

riceball777

I don't want to run meth injection. The car will be tuned on straight 91 octane and on e85. But the car will run straight 91 octane 99% of the time.

So does anybody have a turbo recommendation for me and my goals?

Muckman

iTrader: (2)

Your pump gas tune, why did you stop at 395hp? Your turbo clearly had more flow left in it as it made 100hp more with race fuel. My point was your turbo wasnt the limiting factor on the pump gas tune, the pump gas was. If you upsize turbos are you going to make more power on the same pump gas/stock internals safely? If so, then why not increase boost on current turbo? Thats my point.

TheShodan

iTrader: (14)

Please read above.. I gave my recommendations.

effin

iTrader: (1)

this

riceball777

With 91 octane you can only run so much boost and timing safely especially on a 11.1 compression motor. but with a bigger turbo wouldent I be about to run the same amount of boost and make more top end power at the expense of giving up some bottom end power?

Weather I have a 500hp capable turbo or a 800whp capable turbo you will never come close to the turbo capabilities on 91 octane but the bigger turbo should still make more top end power on 91 octane than the smaller turbo, thus resulting is high trap speeds in the 1/4 at the expense of spool and low end power

Take my evo 8 for example. I have had 3 turbos on that car. (stock turbo, gt3076r and a HTA billet wheel gt3582r). The stock turbo is capable of 400whp, gt3076r is good for about 500whp-550whp and the HTA gt3582r is good for about 700whp). As long as you run race gas/e85 and as long as your engine is strong enough to handle the power you can boost however much you want to max out each turbo. but with pump 91 octane I'm only able to boost about 22-24 psi safely. On straight 91 octane gas I made about 315whp with the stock evo turbo, 360who with the gt3076r and 420whp with the hta gt3582r. So the bigger turbos made more top end power but spooled later and lost bottom end power.

now on my s2000 I have a ballbearing 50 trim turbo. The turbo is max out at 501whp on e85 at 17 psi of boost. The turbo makes 395whp at 11psi on 91 octane. Now the question is, what is the best and fasting spooling turbo that I can buy to hit my goal of 450whp-500whp on straight 91 octane? Every s2000 is different but usually on straight 91 octane pump gas 11-13 psi of boost is normally the limit.

TheShodan

iTrader: (14)

But for what you're asking, its rather not possible, because these turbos are running lower than their effective range. The evolution (which is characteristically completely different than your S2000) can do a bit more because of the lower static compression (which is more knock resistant in tuning than your S2000), cylinder head design, and size of the turbo used, just seems as though what you have, will work best. You're not going to get as big as 61lbs/min turbos (at 2.0 Pressure ratios) and make a peak bit of power for half a second (which is what you're trying for, essentially) without a big loss in response.

More than likely, the GTX3071R is about as good as you're going to get with the combination of both with that fuel, compression and use with the most response. For more upper end power, GTX3076R or TR3030R.

Simply an example.

riceball777

Ok I suppose the gtx3076r would be the best choice for my needs.

Tony the Tiger

The bigger turbo will allow more power on limited octane.. Treat the F20C as a built NA B-series motor, and you are boosting it. Your goal is to match a turbo that can fully maintain that curve for both your low boost and high boost E85 modes. As you flow more air into the engine, that relationship has to be kept similarly as if the engine was N/A.

If compression and octane is the limiting factor, then your goal is to prevent any sort of heat back inside the engine. It's exactly what you would so if you had a high CR N/A engine that is pinging due to limited octane. The direction of flow must be very biased on the intake side, so no exhaust reversion can occur at all during overlap.

If this car was a big power car on pump, I would personally step up to a GT35R for fastest straight line power on 91 oct; but since you want maximum response and spool (probably for road racing perhaps?) and E85 mode, it's a bit different. To keep it simple, I would choose:

GTX3076R 0.82 A/R if I had a 3" DP/3" completely straight through exhaust and no cats or resonators. I assume you have a decent tubular exhaust manifold already. On the 2.0L and 91 oct with no water/meth, it should be able to hold 460-480 WHP safely. On the 91oct mode, it should be making this power at about 15 PSI of boost, and the larger X-76R wheel will be at its peak 78% efficiency. Perfect combo for highest safe low octane power and best spool within your turbo sizing IMO. With E85, you can still afford to turn up the boost to 550+ WHP and have it "choke" a little at the turbine, due to much higher knock resistance with this fuel.

GTX3576R 0.82 a/r if you have a restrictive exhaust and a high-flow cat. You must step up to a larger turbine wheel or housing because you are limited by octane with a less free flowing exhaust system.

I did tune an F20C with the smaller GTX3071R though.

Here's a dyno graph, but don't emphasize too much about the spool because it had a highflow cat, restrictive 2.5" midpipe and dual 2.0" mufflers . The car hits full boost at about 4500RPM if there was time for it to spool up on the highway.




It's almost 2 years, and still driving. The car went through drag, circuit and some drifting events quite often as well, but it's a daily driver/weekend street car.

TKERacer619

LOVE my gtx3071r. 460@14psi. 84.5mm b18c

riceball777

Thank you for your advice. My car is just more or less a street car that I drive everyday. I just would like more power on straight pump 91 octane with out killing the bottom end and mid range power. I do autocross the car a few times a year just for fun. and yes I already have a good tubular exhaust manifold and I have a full 3 inch custom turbo exhaust setup with no cat.

do you really recommend the .82 hotside over the .63? How much different in power and spool is there from these two hotsides?

I'm really thinking about getting a gtx3576r with the .63 hotside. what do you think?
Also I never really heard of anyone running 15psi of boost on straight 91 octane with a stock f20c. I'm tuned at 11psi on 91 octane and I go to a really well know tuner here in so cal.

TheShodan

iTrader: (14)

Again, we gave the options, its up to you to test them. The switch in powerband between the two turbine housing is minimal. It simply pushes the curve to the upper rpm band. Does that mean MOAR POWAA!!? only when the pressure is increased for top end power. At these low pressure ratios, you won't see any difference.

You must understand that you will NOT get the full use and potential of these GTX series wheels at these low pressure ratios; that's not at all what they are designed for. That can be done on a journal bearing system for the same peak power. On the GT-R and GTX systems, no real changes or results occur under 15psi, even with decent compression like stock.

So, bounce the options around if you'd like on compressor maps, turbine maps and the like, but we've stated to stay on the smaller side of turbocharger choice, to at least get better power band. If you're looking for simply PEAK power at a low pressure ratio, stay big, but prepared to be unresponsive.

Muckman

iTrader: (2)

Tony, the high back pressure/exhaust reversion is a bigger factor in this case than the dynamic compression of high static compression & high boost?