Boosted 3.4 iron head engine....

[ssdurango]

I have a 3.4 iron head engine and I'm running an eaton m90 supercharger. I also have the edelbrock intake manifold. Do you think the intake's design is hurting my performance while under boost? (3 short wide runners and 3 long narrow runners).

Also do you guys think I should eliminate the 'bump' in the intake track of the head?


Thanks
Tom

[34blazer]

i wouldnt grind the hump down comepletly, as it helps steer the airflow into the combustion chamber. however, you can shark fin it. when GM engineers designed the first prototypes of the head, they saw roughly a 10% increase in flow with the humps. bowl blending is where id focus on first, as those are really rough around the valve guides.

[latemodelnewbee]

do not grind down the "bump" in the intake port you will actually reduce the flow of the port GM put it there to help the air go down the bend of the port and into the valve. when GM was designing these heads they picked up 17% more air flow with the "bump" there

[34blazer]

do not grind down the "bump" in the intake port you will actually reduce the flow of the port GM put it there to help the air go down the bend of the port and into the valve. when GM was designing these heads they picked up 17% more air flow with the "bump" there

i thought it was roughly 10%? either way the intake flows around 130-140 cfm and the exhaust is around 100-110 cfm.

[latemodelnewbee]

I'm pretty sure it was closer 17 but i could be wrong, but still that vane is still there for reason removing will be more harm than good.
with the airflow ratio of about 77-78% a single pattern cam could be used and make good power, the old rule of thumb is the exhaust should flow about80% of the intake for a single pattern cam. dual petterns cam came out in the 70's for the crappy emissons heads with bad exhaust ports

[merlot566jka]

with boost it doesnt matter about the shark fin....look at turboz2.com curtis walkers engine sure didnt have them....

here is a set of heads i did

[34blazer]

i agree, the humps just take up space. the gained volume in the port will help, but not for daily driving. i wouldnt take them completely down unless i was building an engine like curtis'.

[latemodelnewbee]

the volume gained by removing the vane won't help anything on a NA motor it will actually hurt the performance and barely gain anything on a boosted motor you will probally break even. your best bet for porting is to grind the vane smooth and leave it there.

[ForcedFirebird]

This is actually a big discussion.

Yes, the fin decreases flow, but have shown to increase performance in real-life testing.

Many racers of the past would actually JBWeld a paperclip in the center of the port...

http://speedtalk.com/forum/viewtopic...ight=paperclip