4000GT - MKIV Supra 1UZ turbo - update

[JustenGT8]

You'll need a bit more than 18psi me thinks, unless you tune on E85 for more advance and even that would be tight. heads slightly decompressed will take 20psi no probs, especially on E85 and that would do it. 600rwhp is a nice round figure to aim for

530odd rwhp was the best mine could manage on 17psi and (no offense) my exhaust is a bit better optimised than your current setup.

 

[4000GT]

What did your heads flow? I have a massive CFM gain, big valve head and cams and race springs to suit is part of the head work...

 

[JustenGT8]

Whatever stock heads flow? With the stock intake manifold in place...cams, headwork, valves seem to make little difference, plus those exhaust manifolds will hold you back at some point. The big hp gains are there if you can raise the rpm peak hp occurs at...which happens as soon as you ditch the stock intake. Not that the stock intake is a bad thing...just designed for a difference purpose.

Still, we are both very close so it will be interesting to see which mods do the job to get there

 

[4000GT]

Yeah totally agree on the rpm thing. Another 1000 usable and it will unlock another 50+ easily.

 

[JustenGT8]

Yup, even a conservative extension of our dyno plots could result in up to +80rwkw....that would be nice

 

[4000GT]

As you can see mine tips over just after 5,000rpm, when does yours?

 

[JustenGT8]

As you can see mine tips over just after 5,000rpm, when does yours?

 

[JustenGT8]

That's my base plot approx 320rwkw on 12.5 psi versus one of the twincharge runs. While we had some troubles with the twincharge run it does show that a short runer manifold 'straightens' out the hp curve.

tapers off just after 5000rpm same as yours. plot shape doesn't change much at all no matter what boost level you run

 

[4000GT]

We need a reliable 7,000rpm redline... Its possible... guess it means the head work as planned and a designed intake. Still amazes me there isnt an off the shelf solution. Guess people just dont want to pay for it.

 

[JustenGT8]

I have been speaking with 'people' about an off the shelf option....see what happens i guess. In the mean time i'm looking at options that should still work but for the more budget conscience

BTW, just ditching the stock intake gets you peak hp pretty close to 7000rpm, stock cams/head in place and decent exhaust. Bolts on FTW in this case.

 

[4000GT]

Yeah I really want an intake solution that...

Retains the stock fuel rails etc, and the stock TB, so that doesnt have to change and add $$$ for just some bling. Really we are talking about a laser cut flange, some tapered tubes, and a plenum with fittings attached. It doesnt have to be nth degree tuned perfect, its a FI application afterall. Heck might even be worth getting the A1 turbos ITB bottom cast section and build some plenum on that?

 

[JustenGT8]

Yup, looking at something like that. I have the CNC TB flanges already. The A1 manifolds i saw needed a fair bit of work to finish off...porting etc, so didn't strike me as being that cheap? Would form a pretty good basis though.

 

[Pro]

maybe a custom top plenum might just be the go?

design it with bellmouths into the stock port matched runners and at least 4.0L capacity with a stock TB...?

i was looking at a pair of 4bbl throttle bodies on the stock lower half of the manifold with a thin CNC adaptor plate with skewed ports to suit the slightly different shapes.

but that's for an all-out NA assault, as an alternative to the 8x TB setup.

 

[cribbj]

Justen, what happened to the idea of using a Richwood manifold to replace the lower manifold, then build something to adapt the stock upper manifold to it? Or custom make an upper to have the TB pointing anywhere you want it.

That would get rid of the lower unit, which you've proven pretty conclusively to be the culprit in the 5200 RPM power point fallover.

The Richwood manifold could do with some bellmouths, however.

 

[Pro]

is the lower half of the manifold where the flow restriction lies?

sorry - i had no idea. might help if i was on a little more.

 

[cribbj]

Here you go Aaron: http://www.lextreme.com/forums/showthread.php?t=9356

It's quite a read, but worth it.

 

[4000GT]

I really think the A1 turbo's lower half that retains the stock fuel rails (was for ITB), and the just make a box on top is the easiest way to go.

 

[JustenGT8]

Justen, what happened to the idea of using a Richwood manifold to replace the lower manifold, then build something to adapt the stock upper manifold to it? Or custom make an upper to have the TB pointing anywhere you want it.

That would get rid of the lower unit, which you've proven pretty conclusively to be the culprit in the 5200 RPM power point fallover.

The Richwood manifold could do with some bellmouths, however.

The Richwood manifold is still on the cards John. It needs more work than the A1 manifolds though and i have a similar but better option. Basically you need to hit the Richwood manifold with the die grinder as getting bellmouths in there is next to impossible. Just time so not expensive as such.

All the options i have lined up use the stock fuel rail as it'll never be a limiting factor and all will place the TB in the stock position. They could all be built with a front facing TB but the stock one is more than enough for the power levels that Andrew and i are looking at.

 

[JBrady]

It seems like the 1998+ vvti intake manifold would do everything discussed here. It has internal butterflies to shorten the runner lengths for higher RPM power and is a downdraft design with a front mount TB.

Granted, the mounting surfaces are not the same but it would seem like a pair of wedge shaped adapters would do the trick.

 

[4000GT]

So we decided to put it on the dyno at the car show and put another couple of pounds of boost into it, now around 16psi... made 489WHP