Hutch

Anybody have flow numbers for a set of "off-the-shelf" CNC LT4 heads?

RichS

http://u2.netgate.net/~jshapiro/heads Here are some flow #'s of other LT1 and LT4 heads. No CNC LT4 though.

GS #883

Hutch,
When I upgrade my LT4 with the More Perf package in Feb/Mar, I asked Mike what the flow rate of the heads would be. He said, "THE HEADS WILL FLOW APPROX 280 CFM (iNTAKE) AND 185 CFM EXHAUST." He used REV severe duty SS 2.00 & 1.57" valves with high flow backside, also 10 degree valve locks and titanium retainers. That is his generic LT4 head. Individual flow testing would be an extra charge. He has checked repeatedly and found this is the flow rate for heads he recommends in the 450 HP package.

It has worked well for me. I have driven it 6-7,000 miles since then, including the trip from MA to Carlisle, PA and area, where I met you and RichS, a couple of skunks. The motor makes some power, even though I did not replace my SLP shorties with long tubes, as Mike recommended.

See you around.

RichS, do you still like your Corsa. I just bought one. I can't handle the 3 inch SLP resonance.

RichS

Yes I still love my Corsa! Especially with the lontubes. :crazy: I might be adding bullit cats to tame it down a bit since I'm doing heads and cam work over the winter.

Hutch

Paul -- Thanks for the flow number estimates, but you needn't sell me on More Performance. That's exactly the same setup I've got in GS#633 which I got from More Perf last year. And I'm sure the flow #'s he's referring to are for his package installed in CNC LT4 heads (which he sells a ton of).

Rich -- I just installed Random Tech bullet cats behind TPIS long tubes. The sound is great and even my wife didn't think they were any louder than with full-size cats. And believe me, she'd notice! :) I also had some "test pipes" made up to slip in place of the bullets for competition use only, of course. ;) Once I get a little quirk in my power band ironed out, I'll do back-to-back dyno runs with the bullets and the test pipes to see what kind of HP and noise difference they make, if any.

Rich -- Thanks also for that link with flow numbers but what does that "Source" row mean across the top of each table?

ralph

Rich, i was looking at your link and noticed the AFRs seemed to be the only heads that had advertised and actual flow numbers. Should i assume that all the other flow numbers for all the other heads were verified and matched their advertised flow??? Or was AFR the only brand checked against advertised???

I ask cause i've heard claims of AFR flowing less than advertized....however those claims are usually from someone who is trying to sell their head or their porting package. The best unbiased test that i've seen was done by Chevy High Performance. They tested several heads on the same brand new top of the line flow bench. They spend a lot of time explaning how they set up the test and the equipment they used. In that test, the AFRs flowed almost exactly as advertized...in fact they flowed a little better at low lifts and out flowed just about every other head in their class (Mid size ports 170-200 CFM i think). I also see track results and the AFRs usually do well in street/strip applications and many moderate race applications. So when i hear claims of AFR not flowing their advertised numbers, i'd like to know the details. Not that i don't believe that someone measured the AFRs at 245cfm, but flow bench numbers are NOT absolute...they are relative to some degree, particularly when it come to setting up the test. So i find it unfair to say AFR doesn't flow their numbers without providing some point of reference (like how did other heads do on THAT flow bench on THAT day with the SAME setup and the SAME operator, etc).

I know you didn't make up the numbers and this is NOT directed to you in any way...just an observation from an interested party.

RichS

I didn't do the testing just found the link that someone else posted last year. I used it as a referance to compare my LT1 heads when they were done last year. There is a E-Mail address for the page jshapiro@netgate.net maybe it's still good.

Mez

Check this site out for comparison of different heads including the LT4. The 'Flow Index' is an interesting concept.
http://www.fierolt1.com/lt1_lt4_headflow.htm