Turbo to produce 400hp at wheels?

[mtopxsecret6]

I just want peoples oppions on what turbo to run To give approx 400hp at the wheels. Prefer full boost around 2500---3000 to 4000 max. And keep boost through to 7-8000rpm. I know that it will take longer to spool up than what i have, but maybe a hybrid setup would compensate lowend, and provide for highend? Im also looking at a sequential setup, but, im just looking at all the options before i decide on which avenue i will fully look into.

Thanks.

[Steve]

What engine?

[SHUTO-BOY]

garret gt30 is the way to go

[mtopxsecret6]

Sorry, it will be for the RB20.

[Roy]

I think you will be striggling to make 400hp at the wheels out of an RB20.

Not to say it cant be done, but considering you want full boost by 4000rpm, i say its not likely.

Its my opinion that the only way you are going to get the power is with good internals, some headwork, and say 1.5bar of boost on something like a 2835.

In all seriousness depending on what you have already done to your car it will cost around 20 grand.

[Steve]

Yeah, big ask for an RB20. Expect a fair bit of lag, I think 4000rpm might be a bit unlikely, probably closer to 4500+.

You have to consider that with making power out of a turbo - if you want alot at the top, it will cost you down low. The sooner a turbo spools, the more back pressure you will have at higher revs which in turn kills power through reversion of exhaust gasses, poorer cylinder scavenging and the resultant increase in detonation requiring less ignition timing.

The other problem you 'may' exrerience is if you drop the turbine housing down too small, the turbo will spool up too quick, producing a greater flow of air than the engine can use - this will cause compressor surge where the air reverts through the compressor and robs you of more power - also not good.

Bottom line, unless you are building a drag car with close ratio gear box (you will need to replace the rb20box as it will have died long before 400rwhp), you would be much better with something that comes on boost a bit earlier and gives a strong midrange and a reasonable top end. The HKS2835, AX53B70, T518Z or similar would be my choices. Good response and wont run out of puff too soon.

[Cubes]

An RB30DET can get pretty close to 400rwhp with full boost on at around 3500rpm.

Sydneykid has had a RB30DET making 350rwhp with full boost on by around 3000rpm.

The old saying goes in this situation:

"There's no replacement for displacement" :burnout:

EDIT: Steve.. Didn't yours make full boost around 3000rpm?!? Or is that just when loading her up?

When I say full boost I am talking around 1bar.

[Steve]

Yeah, around 1 bar at 3000rpm. I have gone for a larger turbine housing, 0.87 up from 0.61 (sitting waiting to be fitted) so it will probably add around 500rpm to spool up but should give me better top end. I am also fitting cams and cam gear, but I believe it wont go too far as I am also dropping the compression to 8.6:1 which is pretty close to the RB20 CR.

[Roy]

mtopxsecret6... rise to the occassion and build a tough RB20.

[rbs13]

what about all the srs that have huge turbos on them.. go for something like a t67 but it will require 1.5bar.. see how that goes.. also get cams, cam gears.. fmic, pump, injectors, regulator, exhaust, ecu.. get something like 4.1 or 4.3 diff gears.. keeps you on boost JUST incase.. cant think of anything else atm

[Cubes]

The R32's already have a 4.363:1 Diff ratio.

Keep in mind that its harder for a short stroke RB20det to spool up a large turbo compared to a long stroke SR20 that blows a big long blow in to the turbo, the RB20 has little puffs in to the turbo.

[rbs13]

what revs would a r32 sit at, at 110 in 5th.. i was under the impression i had 4.3's but i sit at 3800 at 110 in 5th! i dont think a production car would sit up there.

[Steve]

Originally posted by rbs13

what about all the srs that have huge turbos on them.. go for something like a t67 but it will require 1.5bar.. see how that goes.. also get cams, cam gears.. fmic, pump, injectors, regulator, exhaust, ecu.. get something like 4.1 or 4.3 diff gears.. keeps you on boost JUST incase.. cant think of anything else atm

And how many of these make good boost (useable) under 4krpm?

Its all good if you want to do cams, manifold cam gears, port etc but it will still be battling to make it under 4k.

1.5bar on a t67? now where up to 5k+rpm.

Its all good if you dont mind winding the rev limit skyward, but I do believe the SRs are a bit better suited to this, I wouldnt like to take a stock RB20 much past 8k for too long or too often.

[rbs13]

id rather take a rb20 to 8000-8500 than a sr20...

[Sydneykid]

Hi guys, the short stroke and larger bore ratio of the RB20 makes it more likely to rev higher and easier than a square (same bore and stroke) SR20. Plus the RB20 direct acting (on the bucket) camshaft is a much better system than the spindly rockers on an SR20. The only possible advantage an SR20 has is more valve area per cylinder, due to the bigger bore diameter allowing larger valves. But 24 valves versus 16 may well make up the difference anyway.

I have never actually worked out the total valve area and compared them, a job for another day perhaps.

Hope that helps

[rbs13]

yea, those were the reason i was going to state. i know getting 1.5 bar out of a rb with t67 would be a mighty 5k.. but it would rock!! anyway.. why does mtopxsecret6 want 400rwhp? braggin right? want good times? you could get better times with a smaller turbo/less power so think really hard about WHY you need 400rwhp

[Roy]

I wouldnt like to take a stock RB20 much past 8k for too long or too often.

I agree with not reving your car any harder then it need to. But RB20s only have 69.7mm stroke as well which also help them rev. If your engine has good cool supply of oil and coolant, then i dont think its too much a drama. How often are road cars at sustained full trottle high rpm load?

[Steve]

Good points sydneykid.

But I would really love to see a sr20 or rb20 spool up a turbo to useable boost before 4000rpm and will comfortably make 400rwhp - and a T67 is a pretty big turbo I would even more so love to see that particular turbo make useable boost under 4k on an Rb20 - or even an RB25 whilst still using a turbine housing that wouldnt choke it before 400rwhp.

[rbs13]

im trying to find an article.. had a sr20 with t67.. cams, cam gears i think, 1.5bar... power fc i think.. ill post up spool revs, power etc.. then again its a magazine.. it MUST be true.

[Sydneykid]

Hi guys, the way I look at is, I need a car with good average power over a minimum 3,000 rpm power range. That allows for the drop in RPM after an upchange. With 1st to 2nd (as usual) being the biggest gap in a Skyline.

So if I have an RB20 with good average power from 3,000 rpm to 6,000 rpm or from 5,000 rpm to 8,000 rpm, it doesn't really matter. The problem comes from when you have an engine that makes a good average from 6,000 rpm to 8,000 rpm, then you have a real problem. It takes too long to regather itself after the gearchange and is therefore slower accelerating than its maximum power would indicate.

As I always say, it's all about the average not the max.