Getting more power

[Akane]

In the MR2 im running 275 rwhp at the moment on grippy tyres 225/40/17 Falken FK452 on 8" wide rims and can break traction in the dry between 50-80 kmh.

ok i stand corrected, last night I've hit a peak of 1.11kg/cm^2 and in second I got the mad tyre hopping from 4krpm to 7krpm in 2nd.....

Maybe need new tyres and new shocks ........

[LEAKER]

might need the diff adjusting so both wheels are getting proper traction?

[Boosted_162]

He was just trying to prove his plate is occasionally true

[Akane]

might need the diff adjusting so both wheels are getting proper traction?

It's got a factory LSD, not really adjustable.

He was just trying to prove his plate is occasionally true

The plate is a lie, I am a sensible and safe driver

The problem is that I don't have access to a dyno, been playing with my ignition a lot and sometimes I get good power out of the GT28RS sometimes it goes like a sack of potatoes.

[MAGN1T]

Or just check your tyre pressures?

Steve

[Rookie]

If you want good spool and 400 hp out a a 2 litre, a compund setup is your best bet. Something like a gt35 (or bigger) with a big turbine A/R and a Eaton m90 SC would be awesome.

The turbo assists the supercharger, and the supercharger assists the exhaust turbine. the blower multiples pressure changes, so while it may be contributing 5psi when it's there alone, when you feed it a compressed air charge the total ratio changes significantly. the turbo is probably only doing 2-3psi at the moment, for a total boost pressure of 9psi.

WRT matching, the supercharger needs to be big enough to provide you with approximately half the total boost pressure. that's really all it needs to do. experience will tell me which blower to use. on an SR20DE, i'd go for the little toyota blower, the SC-14. on an RB26DE, i'd use the Eaton if i could fit it. for the RB30DE, the eaton is borderline too small, but it gets the job done. i still have a fair bit of scope for overdriving mine, which i may do in the future to make it even more cranky.

of course this changes if you want to make huge power. above 600hp i'd go to a twin screw blower, or an Eaton M112 (next step up from the M90). packaging such large blowers in with a giant turbo becomes a bit of a problem then.


the turbo needs to be carefully matched so that it doesn't come on too early and restrict top-end power at all.

generally speaking, you go for a turbine stage that flows roughly 1.5-2x as much as the one you would choose for a very responsive single turbo setup. hence, i have a GT40 with a 1.34 rear housing. it's pretty hard to go too big on the rear housing really, i mean that rear is just gigantic and i still have excellent turbo response. the next step up is a GT42, which wouldn't really physically fit in the bay.

matching compressor sides is a bit trickier, you generally need a big A/R on the compressor side. this will increase the available flow at lower pressures. you need this because the turbo (in my case) will be supplying 400hp worth of air at just 2-3psi. so you see the need for high flow capacity with little pressure output. the potential is there for it to surge of course, but i haven't had a problem with that. it is certainly operating well outside it's "normal" parameters on the flow chart.

He has a compound charged RB30.

You want to replicate this system, but if you only have room for one intercooler then thats fine too, just miss out the one between the turbo and SC, and keep the boost down(<20psi) and make sure efficencies of the SC and turbo are as high as possible.

[LEAKER]

I don't have room for a supercharger, barely have room for the intercooler piping at the moment.

[RedMist]

Borg Warner EFR. Tidy package that includes recirc BOV and dual valve wastegate. When you consider the purchase of external wastegates/BOV and thier installation the EFR suddenly becomes very cheap. It's also got a higher flow and larger boost islands that a clear majority of existing turbos. Which means you can pick a smaller frame (better response) and still flow enough to get high HP.

[Akane]

Borg Warner EFR. Tidy package that includes recirc BOV and dual valve wastegate. When you consider the purchase of external wastegates/BOV and thier installation the EFR suddenly becomes very cheap. It's also got a higher flow and larger boost islands that a clear majority of existing turbos. Which means you can pick a smaller frame (better response) and still flow enough to get high HP.

Don't really like the idea of integrated BOV, you can't be "doseing it".

But they have huge islands on their compressor maps, very impressive stuff.

[Malcolm]

those EFRs look freaking awesome. If I ever decide to upgrade from the CT20b, I think I'd almost certainly get one of them. I'm pretty sure their smaller one would have a higher power potential and similar or faster spool than the 20b, plus the internal BPV, decent internal wastegate and integral boost control solenoid are awesome ideas.

[Lith]

Yep even the EFR6258 do awesome, I had been thinking about going for a twinscroll EFR7670 for my Skyline but despite BW being a well proven brand I wanted to wait for some proven results. As it stands, despite a NY release promise there are STILL huge supply issues and there have been quite a few failures considering how few of them have hit the consumer market.

I gave up waiting out the teething issues.

[Grrrrrrr!]

Compressor map looks nice, wonder what the turbine map looks like. Anybody seen one.

[Lith]

I've not seen any for them, however none of them (aside from maybe the EFR9180) seem to me to be likely to push the flow of the turbine side just reading between the lines.

[Grrrrrrr!]

More interested in where the boost threshold is. Looking for something that spools up nice and early. Is there some way to work that out from the compressor map?

[Lith]

Nope.

Also a boost threshold on the dyno will never fully match what happens on the road so isn't necessarily a good representation. With my old GT3076R I would have 1bar before 3500rpm on the dyno, but 1000rpm or more later in 1st gear... largely because it goes through the rpm so fast and the turbo gets hardly any time to pick up shaft speed fast enough to meet the ever increasing demands of it.

[MAGN1T]

That's not really boost theshold. You find that in top gear going up a hill.
What you get in first gear is "lag" which is mainly caused by inertia of the compressor and turbine wheels.

Steve

[Lith]

Well yeah if you want to pick nits - but the being pedantic about the definition of boost threshold isn't relevent to the point I was making. The boost map from a dyno will be closer to the potential boost threshold than what you're ever likely to experience in most conditions you'd be using the turbo for (especially the way Chequered Flag ran the dyno, where it would force the engine speed to settle every few hundred rpm). Our engines aren't used steady state in the real world, and even going up a hill in 5th you will experience the lag even if technically full boost is reached by particular rpm... eventually.

Say a Stage III T3/T4E with 57Trim compressor wheel, .63a/r turbine housing for sake of arguement might be capable of the same (or similar) boost without wastegate control at WOT steady state at 3500rpm as a .82a/r GT3076R, everything else being equal... but driving both setups back to back will yield quite different driving experiences.

I tend to be a bit more interested in lag when deciding on my end target, and just acknowledge boost threshold as a rough indicator of where in the grand scheme a particular turbo might sit in terms of driveability.

[RedMist]

Matchbot will give you a brilliant, if not very conservitive estimate of a majority of the variables concerned. It's fantastic in terms of turbo selection. Includes a basic dyno plot.

http://www.turbodriven.com/performancet ... index.html