Which size Venti-Port?

rluciano · 01-19-2010, 09:40 AM

I emailed Henry twice asking him and he answered my other questions but whether to use the 36 or 40mm venti port insert. My engine is 3.3SS. 100mm Nickies and JE Pistons at 10.1:1 (was supposed to be 10.5:1, but when cc'd it only 10.1:1.) DC60-106 cams. Stock rods with ARP rod bolts and nuts.

While Aaron was at SuperTec he twinplugged my heads and put on Supertec valve springs, asc-102 Titanium valve spring retainers, teflon valve stem seals, new manganese bronze guides and new TRW 3071 and 3070 valves.

I have Hargett ITBs with 48mm butterflies and 40mm ports. I haven't decided on which Venti-ports to use. For some reason, even with 40mm port on the ITBs, the 36s look right.

Which would y'all advise for venti-port size?

Thanks

Eagledriver · 01-19-2010, 03:46 PM

That's a pretty big motor and high RPM setup for 36mm ports. I'd try the 40's myself. Can't you try them both? See which one you like best?

-Andy

rluciano · 01-19-2010, 04:23 PM

I probably will try both but if the one I try first works well after tuning I may say good enough. I also have two exhausts to choose between. I'm hoping not to spend a fortune on the dyno.

Henry Schmidt · Henry Schmidt's Garage

If it is your plan to run sustained high RPMs then run the 40.
If your plan is to take advantage of mid range RPMs then run the 36.
We built a 3.7 that pulled strong to 7200 with 36 mm Venti port.
Our flow tests showed flow characteristics comparable to factory 3.0 RSR porting (43mm) from the 36 Venti up to 7100 RPM.
Remember that port velocity is key unless the goal is 8000 RPM.