Twin s366 down pipe size
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Launching!
Joined: Jun 2012
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From: Pennsylvania
Twin s366 down pipe size What would be the best down pipe size for twin billet wheel Forced Induction s366s? Engine is a 6.0 ly6 stock crank with forged rods and pistons. Shooting for 8.99 so what ever boost it takes to get there. A few opinions were to go 4 inch but may have some space issues.
4" would be the "best" because the S366 comes with a 4.21" borg specific (marmon) v band exhaust discharge. If you have space issues though I would go 3.5". Giving up a little but you should absolutely still be able to hit your goals in terms of making power.
I believe the turbine side of a SXE366 is 73mm exducer/80mm inducer wheel. So if that's the case the diameter of the exducer is 2.87", but would have me curious as to what the back pressure impact would be on say 3" vs 3.5" vs. big boy 4" especially in a Twin application as you are not trying to cram all that exhaust from both sides of the engine into a single housing. I've read of a 120% rule on the exducer, so that would be 3.44".
I believe the turbine side of a SXE366 is 73mm exducer/80mm inducer wheel. So if that's the case the diameter of the exducer is 2.87", but would have me curious as to what the back pressure impact would be on say 3" vs 3.5" vs. big boy 4" especially in a Twin application as you are not trying to cram all that exhaust from both sides of the engine into a single housing. I've read of a 120% rule on the exducer, so that would be 3.44".
Either way I agree 3.5" would be ideal, especially to your point of it being in a twin configuration and only seeing 1/2 the engine exhaust volume. Hell even 3" would probably be totally fine.
Last edited by blackdak318; Jan 29, 2021 at 04:46 PM.
Thread Starter
Launching!
Joined: Jun 2012
Posts: 249
Likes: 36
From: Pennsylvania
That’s what I’m really looking for is to see what kind of power can be had with 3 inch. Just seems crazy to run 4 inch on those things when everyone and their brother necks down the 96x88 turbine to 4 inch.
Agree. I have a 4" on my 91/102 and made 1008 on 23 psi no problem. If you wanted to run the 3" I think that would absolutely work. You're giving up a "little" but in the grand scheme probably not enough to be concerned about. I full recognize I'm giving up a little with by 4" rather than 5 but really don't care. I can't use what I make for 90% of my driving/racing anyway so it doesn't concern me.
