If you look at the flow numbers on the fieroLT1 page, you have got some really nice intake numbers. But it does look like he's left something on the table on the exhaust side.

Closest comparison is the GTP Race LT4 at 313/233 (0.6) But it doesn't tell us what valve sizes they used.

In fact, looking at the stock LT4 exhaust numbers on that page, he hasn't picked up much over stock on exhaust except at high lift.

 

He is working on my LT4 inake but Bret Bauer of Bauer Racing who is doing the custom cam told Lloyd that to see more power up top that I would need to convert over the the victor junior intake. He told Lloyd it would help up top where the Lt4 has problems.

 

These larger valve seats and larger valves allow alot lore air from thes ecastings. They are both great #'s.

As far as exhaust #'s . . . . . I flow with out a pipe and that might be some of it but you can't argu with the power people make with my heads. You can probably find some people that are happy with the performance and HP #'s of my 190 cfm exhaust port, LOL.

I have YET to see a 220 or 230 cfm exhaust port like most claim. I have seen #'s in the 175-185 range for heads that "claim" 215-230 cfm so I am not sure if my bench is a lil low on the exhaust or what. I have had stuff reflowed on other benches and it checks out similar so I doubt if it is my bench.

Maybe others flow with a big pipe attached or maybe even a vacuum cleaner, LOL, but I have seen VERY few LT1's with #'s over 195 cfm on the exhaust on my bench.

If you see a company claiming over

110 cfm at .200
140 cfm at .300
175 cfm at .400
190 cfm at .500

they must have flow #'s from different heads than the ones theys sell to the average guy because I have NOT seen anything that high from LT1's on my bench and I have flowed ALOT of LT1's from various companies/porters. As I mentioned, our benches must be a lil different if they get 230 cfm from an exhaust port, LOL.

Rob,
-Intake ports are 217 cc for the LT4 with 2.08 valve and 208 cc for the LT1 head with 2.05 valve. Chambers are gonna be right at 55 cc for each. Heads are still getting milled, cleanmed and assembled so I do not have final #'s here yet.

Lloyd Elliott
972-617-5671
Eportworks.com

 

I think you meant Super Victor. The runners are longer and it flows better than the Jr.


http://www.edelbrock.com/automotive/index.html

Click on Intake Manifolds in the left block, then
Small Block Chevrolet then,
Small-block Chevy Race manifolds

Compare the pics and write-up of the #2975 Jr. to the #2925 Super Vic.

 

Lloyd, I appreciate you sharing numbers with us. I was wondering if you thought such a huge intake port would slow velocity down and make a peaky horsepower?

As far as going with a Super Victor.. Isn't that a bit overkill? I mean, most agree a 500 rwhp limit for a typical LT1 style intake just because of plenum volume. Heads with an intake port of almost 220 cc would definitely be good for a big cubic inch engine and then would probably necesitate the using of a Super Victor.

As far as exhaust flow. We got my heads to flow around 209 CFM at .550 lift @ 28". We didn't go after huge airflow numbers in trying to keep the intake port velocity up.

Not trying to be a dick or anything, just trying to learn more about head flow and it's effects.

 

Velocity at the valve seat is the most critical area in my opinion and as long as it is good here, the LT1 head can NOT be too big. If the port is shapes wrong or has a crummy valve job, you might lose TQ but with a nice valve job anbd correctly shaped port, I do not think an LT1 head can get too big.

My LT1 heads that use stock valves are over 195 cc and the ones that have 2.00 valves are over 200 cc. People use either of these heads with mild cams like the Hot Cam or CC 305 and talk about how much MORE low end power they have over stock heads.

If you have a a 6500 RPM 350, a 210 cc intake port is fine.

If your set up really needs the LT4 heads like I mentioned, it is a 6800 RPM 350 or a 6400 RPM 383 and the 220 CC intake port is fine.

I would not wanna use that typoe of LT4 head with a Hot Cam on a 350. The LT1's mentioned above would be a beetr choice.

Lloyd Elliott
972-617-5671
Eportworks.com

 

Thank you for clearing that up. I wasnt sure if that was right or not.

 

Even if there was more exhaust flow the 2.08/1.60 combination is going to warrant more exhaust duration anyways.

I like seeing good exhaust flow numbers on street cars because SOMETIMES you can cut back on the exhaust duration and help TQ, but most times the cam still wants some extra exhaust lobe to get the motor to keep the HP hanging on after peak.

I would guess first that the heads are in that territory. Most 290-300cfm LT4 ports I have seen are 215-220cc. I had a Ai LT4 was 219cc, a TEA head that was 215cc, a set Larry Meaux fixed for me that was 220cc range. They were for a variety of motors from a 350-396.

Out of those setups they were anywhere from a 2.00" stock valve, 2.02" and a 2.055". .400 flows anywhere from 241-252, .600 flows from 297-288 on the intake. As for the exhaust numbers ranged from a peak of 200cfm to 234cfm.

As for the Super Vic, how is more TQ and more HP ever overkill. The problem with the LT1 isin't just the plenum volume it's the short runner length and the lack of flow you get out of them.

Bret

 

im getting ready to put some LE heads on... This is my 2nd LE heads.. The first set where his abesolute cheapest heads.. and a great deal on em... After i put them on the car ran like a bat out of hell.. These next heads are alittle better cant wait..

His old heads only flowed 255cfms at .550 or so.. But i tell u what the car ran hard.. Im not a big believer in CFMs... much more too it like velocity.. I found this out after getting heads that flowed much more... the car ran much slower.. So back to llyod it is.