Anti-Reversion cone in turbo down pipe & more overlap

Been knocking around using more overlap on a turbo motor to improve VE and was wondering if a custom 3" or 3.5" down pipe fitted with an anti-reversion cone sounds like a good idea? I know the cone will improve idle, but the extra thermal load causes concern.

Any thoughts?

eh uhm well, I dunno that thats as big an issue on a boosted car, the major exhaust bottle neck is indeed the turbo, which has an uncanny ability to "blend" pulses a bit.. my car with 2.5 inch straight exhaust has some velocity behind it just at idle, and while you can fell the pulses a bit, I dont see any chance of reversion.

However I'm hardly an expert on this topic, so perhaps bondo or one of them will come in and back me or tell me why i'm wrong and should shutup :wink:

I've only heard of cones being used for NA applications.

Three Fat Tigers said:

I've only heard of cones being used for NA applications.

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Thanks, after much research I find no turbo application.

Yes you can use them in turbo apps. You would need one in each exhaust manifold runner near the head to be effective. You would have to carve them into the runners. I have no idea what kind of power gains (or losses) you'd see with more overlap in a turbo setup.

My guess is that for a turbo engine it's kind of a bandaid fix. Like if you have a add-on turbo kit and can't find the right cams.

But try it and let us know. BTW I found something about them in Corky Bell's "Maximum Boost" good book - read it.

I forgot to mention they were only used when there wasn't enough room for tuned headers, and like Hoggster said, one in each runner right next to the head.