Would you benefit from having the intake extrude honed??

 

Wow, definitely wouldn't have them doing my heads. I got a port job done that flows 265 @ .50 NOT .55 and that's w/ stock sized valves. The shop that did mine has extensive dyno results that does show that port-matching the intake manifold does make a big difference, but alternatively, if you opt for their after-market, AFR based heads that flow 287CFM w/ that same intake manifold and same (this was a big solid roller cam) you gained an additional 31-39hp. If what that shop is saying was true and the manifold was a major restriction, you wouldn't see that kind of gain.
What is this shop claiming for the exhaust flow?? That head job better cost your buddy under $800 if they're only flowing 260@.55

 

Plenum volume is where it's at - I just haven't figured out exactly how I'm going to add it just yet.

 

Bingo! BluEyes gets the prize on this post.

Intake manifolds and tuning pressures are alot more complicated then you think. The flow thru them is about 50% the reason why they make power. That might even be too much credit to the flow.

I recently worked on two super vics for a engine. One was port matched and ported. By port matching I mean doing it with a mill the right way, not gasket matching. (that's a fast way to screw up all the tuning effects.) The other one was epoxied and each runner was made to give the engine better tuning down low. The intakes had the same runner length in each manifold, the one that had the epoxy in it flowed about 15% less and this was thru 300cfm heads, (270cfm @ .400). The funny thing is that it made more tq below peak, increased peak TQ and had the same HP! The engine it ran on was a high compression street gas motor with hyd Rollers and a carb. How the air/fuel flows thru a intake is more important than how much it flows. EFI cars are even easier to work on since they have dry flow rather than wet flow.

Port volume, runner length, runner area and taper angle all have a huge part in manifold design. Plenum area does too, but i've seen people experiment with that and do nothing but screw up the tq curve on a EFI motor, on a carb motor it can make all the difference.

BTW- every engine needs a different optimized intake, the displacement makes a huge difference intake to intake.

Yeah I gotta agree, flow numbers in heads are always going to give you more power even if the intake sucks.

Bret Bauer


Hey if anyone has a spare LT1-4 intake drop me an e-mail @ bretbauer@hotmail.com I might be able to see what and where you can improve that thing.