Any results on Siamese vs Ported intake - ZR-1 Net Registry Forums

LGAFF · 10-05-2009

I have a spare plenum and a set of IH cores on the way back to me(hopefully). Does anyone have Dyno results showing impact of a siamesed plenum vs 36mm porting?

I was thinking of doing one. I am very interested in it for my 92 with 4.09 gears.

Thoughts??

Pete · 10-06-2009

Lee,i have done huge siamesed plenum and huge siamesed IH's on my Z.
I did a before and after dyno with no gains just some low RPM loss from
what i can remember 10+- rwp, it was a while ago.
I have dyno sheets somewhere in my garage file cabanet.

On big cube motors doing the siamesed/droped plenum,IH is worth 10-12rwhp.
Hogan's intake was worth 12rwhp on a big cube motor over a ported 36mm plenum/IH's
It raised peak power from 6800 to 7k.

I took the divider out of my plenum did not touch the IH's.
Ported plenum/IH's to something close to 38mm.

I have not noticed any change,throttle response is crisp better then
a stock Z.

Pete

10-05-2009	#1
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,194	Any results on Siamese vs Ported intake I have a spare plenum and a set of IH cores on the way back to me(hopefully). Does anyone have Dyno results showing impact of a siamesed plenum vs 36mm porting? I was thinking of doing one. I am very interested in it for my 92 with 4.09 gears. Thoughts?? __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

10-06-2009	#2
Pete Join Date: Dec 2003 Location: Chicagoland,IL Posts: 2,679	Re: Any results on Siamese vs Ported intake Lee,i have done huge siamesed plenum and huge siamesed IH's on my Z. I did a before and after dyno with no gains just some low RPM loss from what i can remember 10+- rwp, it was a while ago. I have dyno sheets somewhere in my garage file cabanet. On big cube motors doing the siamesed/droped plenum,IH is worth 10-12rwhp. Hogan's intake was worth 12rwhp on a big cube motor over a ported 36mm plenum/IH's It raised peak power from 6800 to 7k. I took the divider out of my plenum did not touch the IH's. Ported plenum/IH's to something close to 38mm. I have not noticed any change,throttle response is crisp better then a stock Z. Pete __________________ '91 #1635 PoloGreen 350 LT5 11.09 @ 129.27 11.04 @ 128.86 474RWHP 400RWTQ http://www.youtube.com/watch?v=SFNFOhGGlR4 http://www.youtube.com/watch?v=ZlRIOMwaDYY https://sites.google.com/site/peteszr1garage Last edited by Pete; 10-06-2009 at 01:13 PM.