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gaining spool without sacrificing power, tubular to cast manifold?


msupra1
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My 66mm turbo (Borg Warner S366) with .91 divided housing on divided manifold hits full boost at 4400pm in 3rd. It's even more lazy in 2nd and 1st. This is on a 3" downpipe and 269 cams.

 

Instead of changing the turbo itself, I was thinking to change to a cast manifold.

The Supra is making about 690bhp at 1.65 bar on 50/50 water/meth injection

 

The goal is to make the same power at the same boost level, but spool 400-500rpm sooner. Around 3900-4000 rpm would be better.

 

Is this possible to achieve with a cast manifold? or how can I achieve this with a smaller turbo.

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A cast mainfold would give you great spool but there is a potential of losing some power. The idea would be to get a cast manifold that minimises the top end loss while keeping the great spool (here comes the shameless plug), I have the rare Arnout cast manifold for sale that would fit the bill for your goals

 

http://www.mkivsupra.net/vbb/showthread.php?320903-Rare-Arnout-Cast-Manifold

 

Now to even up my slight biased approach, you could get a gen2 precision turbo like the 6266 or 6466 (depending on your power now) which would bring the spool to a better level and makes good power.

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Cast manifold and mild cams will make an epic spool on a 6266. Something no bigger than a 262, maybe a 256.

 

Agreed ^^

 

A smaller turbo for your powergoals will be much more fun!

The S366 is proven to make over 800whp.

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I thought I'd mention that these are USA Made GSC S1 power-division Stage 1 cams.

On my stock j-spec cams I was hitting boost a 4400rpm as well. These cams are rated to lose zero on the bottom end which from tests is true.

They also make more power and out perform HKS 272's cams significantly. The GSC is a beast of a cam... they are great.

So these cams are not sacrificing bottom end. The build boost up and spool is same as the j-spec cams. It will help a lot with mid range / top end power.

 

I will put this here its a good read and back to back results on just a 3.5 vs 3 inch down pipe .net you 200 rpm spool alone

http://www.superstreetonline.com/how-to/engine/modp-1102-exhaust-test-tech/

 

I've been going back and forth about this. My tuner said that there wouldn't be really much difference, and a bigger downpipe is not really necessary for my power level.

 

Well regardless, if I got a cast manifold, I would have to get a new downpipe made. So 3.5" is something to consider.

I've already been a few single turbo setup's so I don't want to get in over my head, already spend too much money. I wanted to keep it simple, just change the manifold.

Edited by msupra1 (see edit history)
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