I dont wanna throw up the BS flag on my friends setup, but this just doesnt sound right.

These heads are LT1 castings with alot of portwork. Im not sure what kinda valves, but they are stock sized. He claims that they flowed 284 @ 550. That just blows my mind.

Ive never heard of such a thing. He is an honest guy (and I know he is NOT lying, maybe a bad bench) and he does know his stuff, but i have NEVER heard of anything over 270 on stck valves at that kinda lift.

BTW, I beleive there was no welding around the valve pinch, but even then? Any ideas? Is this possible, or is the flowbench off?

 

If the throat of the port (right below the valve) is really big maybe......

Still that's a ton of wind and I would say you are right having your radar up about the BS flag. A 1.94" valve usually can't move that kind of wind at that lift, and if it's in a LT1 casting it's still iffy.

Bret

 

Here's my #'s, on Trickflow heads with 2.02 intake valves.

Int exh
.100 75.6 67.3
.200 155 118
.300 210 156
.400 255 182
.500 285 191
.550 293 196
.600 296 200
.650 296 204
.700 298 208

 

That's really very good. Who did the heads for you?

 

Advanced Induction. They could got more out of them apparently, but seeing as I'm just a little stock bottom ended NA car, These do just fine.

 

Well I got some more info....

They were ported as a demonstration for students at The School of Automotive Machinists in houston by the lead porting instructor. They hogged the crap outta the heads. They used the original stock valves.

Pretty amazing.

 

Makes more sense now. Who's the lead porting instructor now?

 

Im not sure, but I can ask. Just makes you open your eyes about how much potential LT1 castings have. Just imagine the kinda flow #s out of a 2.05 valve

 

I've seen 300cfm castings but the area in the throat was so thin you couldn't run the bastard on a motor.

Then again a 284cfm @ .550 could have a very low mileage valve seat on it. Plus you are not going to pay $500 for that port job, doing that is going to take a good amount of time on the bench and grinder and hopefully all the ports will be that good.

Bret

 

When was this done? The head Class instructor is Casey Snyder, but there have been others in the past.

When I showed Casey the numbers that I got with stock 1.940" valves (272@.600", 273@.700") he said that's probably all I'll be able to get with those valves. I do think there is a little more there... Maybe if he used stock size LT4 valves or an aftermarket 1.940" valve?

Can you get the low lift numbers? Or maybe PM me the student's name?

BTW- Casey told me that the LT4 heads on his personal Camaro flow 330cfm

 

I second this. I just have a hunch that the low lift numbers suck. I have never seen REAL numbers that good with killer low numbers. It might have a valve job that is better suited for the high lift numbers. Just an idea though.

Ken

 

From what I have heard Casey is one hell of a head porter.... Makes more sense now. The flow lift numbers could also be so so as well do to a valve job and port shape that works better at higher lifts.

Thanks for the answer.

Bret

 

this is another possibility. Maybe a 50° valve job instead of the normal 45°?

 

There are a few variables. Portwork is all subjective. very few people actually have R&D done on the actual flow characteristics. Big numbers, at what lift, flowbench etc etc. Look at LPE, TPIS, DRM and LLoyds. I bet the flow at low RPMS is very important to these guys as you still need to drive the thing with some low rpm response. I bet you could grind the living crap out of a set of heads and get 300cfm from LT1's. Doesnt mean squat till they are on a car and driven to a dyno for HP check, and the track, and street.

 

I have seen a set of stock castings go over 300 cfm with a 2.00/1.56 setup, but there were a max effort head, had to run offset rockers etc, car had alot of potential but was never realized..he took it all apart. It ran 10.50's all motor at 3350 lbs. With an auto, had bottom 10's in it.


David