1uz ITB's theory & advantages

[Crambo]

If I had a plenum to take the place of the stock uz top half, that had trumpets on top of the runners fed by the stock TB would this give increased response but less low end torque because I would have reduced inlet runner length by about a third? I'm sure ed would like to make me a custom plenum as he is having such fun with his.

[MWP]

If I had a plenum to take the place of the stock uz top half, that had trumpets on top of the runners fed by the stock TB would this give increased response but less low end torque because I would have reduced inlet runner length by about a third?

You wouldnt gain much response, as youll still be running with a single TB.
Trumpets and a largish plenum might give you some top end power though, esp if combined with cams.

Would be very hard to predict the exact results, would be a try it and see job.

[Crambo]

What I was proposing, I don't expect much in gains more of an experiment and maybe for some under bonnet display (Bling), I am looking for advice/experience from others to tell me what gains or losses I can expect, I think 1uz in MA61, a little lost torque won't be missed if I get something in return.

I thought the shortened inlet runners which I understand long one's are for low end torque, combined with the reduced turbulence of the inlet trumpets would produce more response.

Perhaps a similar trade off when you lighten a flywheel, gain in one area and sacrifice another. ed_jza80 mentioned on a thread about plenum volume, so I must research this before I do something stupid.
BTW MWP, I looked over your work and it is excellent and extensive, no probs with rego going from 4 to an 8?

[clubagreenie]

Eds existing plenum and base *could* be adapted to fit a non vvti. The base adaptor would have to be redrawn, but the top half and mould wold be the same.

[MWP]

What I was proposing, I don't expect much in gains more of an experiment and maybe for some under bonnet display (Bling), I am looking for advice/experience from others to tell me what gains or losses I can expect, I think 1uz in MA61, a little lost torque won't be missed if I get something in return.

If it works as expected (ie, typical effects of shorter runners & slightly better flow), you gain some top end power and loose some lower end torque.
You wont gain any responsiveness... ITBs are pretty much required to make any good gains there.

BTW MWP, I looked over your work and it is excellent and extensive, no probs with rego going from 4 to an 8?

Thanks
Engineer has approved it, still waiting for DOT approval (shouldnt be a problem).
Its all about engine capacity, not characteristics (cyls, power, weight, etc) and the 4L comes in under the ~4.3L (NA) limit for RA28s.

[rms]

Short runners don't automaticaly reduce 'low end' torque. Figures are from unopened 1UZ on Superflow engine dyno. Don't have figures with stock intake though.

[Mos]

There's little point putting throttles on an early 1UZ without removing the bottom half of the manifold.... (just ask rms )

If you want 200rwkw just get a VVTi engine, aftermarket computer and a decent exhaust and you're done with factory reliability

Mos.

[Crambo]

Mmmm, those figures would be good in my "1250"Kg car.

[rms]

Should have mentioned with dyno sheet, manifold is custom straight vertical runners, slide throttle, bellmouths.

Go with Mos, and if thats not enough stick a hair dryer on it.

If you want 'bling' with ITB's your wallet had better be wwwelll padded.