Help! I Keep Warping Exhaust Manifolds And Turbo Housings

[scotty nm35]

1 inch runners will keep the gas speed high too. Unless they are a restriction why go bigger?

[Ryno]

1 inch runners will keep the gas speed high too. Unless they are a restriction why go bigger?

Exactly, when you look at how small the collector to the T3 flange is, it seems bizarre when you read about people increasing the size of the exhaust ports. My mechanic has a drift car with well over 300 rwkw that runs a similar manifold with 1" runners and the small runners don't seem to choking his power output. As you've said, it's all about keeping the gas velocity as high as possible to spool the turbo hard.

[Rolls]

If you keep them small then its believable that it might increase response, when you see people with these massive tubular designs designed for peak power though you will often loose response.

[scotty nm35]

Small runners, sweeping radius and internally smooth pipe joins/merge collector will make a sweet manifold. Anything with large pipe or tight bends wouldn't be suited (at this power level anyway.)

It's interesting Kyle (6boob) won't change his piping sizes, even if the customer requires it for a particular power output.

[r33_racer]

He has made some manifolds with 1" pipes... He was testing them on sr20s a few years ago mainly for street and drift cars where response was favoured. I think he said he found it was only good upto a certain power level before it became too restrictive. Can't recall all the details, it was a while ago now.

[Ryno]

This manifold makes my GT-RS so responsive that you can hear the turbo whistle as soon as you blip the throttle from idle.

Mike at MX said he has fitted this manifold to a RB20 with a 3076, and it hits 20psi at 3600 rpm!

[simpletool]

4 pages to come to the conclusion that a GTRS running 20psi on an RB25 doing track work is going to exceed the design temps? Pretty obvious, HKS rate them at 0.9bar on an RB25.

I wouldn't put more than 1.1 bar through one on a street/cafe racer RB25. You're not just past the turbine flow, you're off the compressor map too.

20psi is around 2.6:1 pressure ratio.

[Rolls]

Where did he say 20 psi? I can't seem to find him saying any pressure at all.

[Ryno]

Rolls, here's a comparison of what the manifold change has done to my power curve (same dyno/same boost/same gear). The increased spooling isn't so evident on this graph, though on the road the change in response in incredible.