I am just finishing up a 383 W/ a Vortech and just got some flow #'s on my LT1 heads and was wondering what everyone thinks. They were flowed before and after on the same Superflow bench. The heads ended up a 305/230 @ .700 278/216 @ .500

 

Very impressive peak numbers for an LT1 casting. what were the stock numbers?

 

Mmmm... I assume they've had alot of material added . If that's at 28" anyway.

 

The stock flow #'s @ 28inch were 205/180 @ .500 & 240/185 @ .700. We didn't have to add any metal and went with 2.02 intake & 1.625 exhaust. The guy I had porting them used to work for AFR and really knows what he's doing.

 

Err.. LT1's simply do not have enough material to literally gain enough crossectional to flow that at 28" depression. Nothing to do with skill... They also wont get anywhere near 240cfm stock.. do you have LT4's?

 

These are LT1 heads. They had a slight DIY port job on these heads when I got them that was done poorly so those stock numbers are a little higher. I will have the flow sheet by the end of the week from my motor guy. Skill has everything to do with porting. There are not very many guys who know what there doing. The proof is in the flow #'s.

 

Skill has a great deal to do with it regarding shape and whatnot, but the bottom line is that no iteration of the LT1 casting has enough material to get that kind of crossectional out of it. Everyone has "280cfm" lt1 heads.. I've had dozens.. the best ever peaked at 264cfm on our sf600, 4.060 bore, half inch clay radius with most peaking in the 25X range. We've welded up several LT1 heads, & you won't get near that w/o adding alot of material. Sorry, good luck with it

 

SkarodoM, All I'm saying is the numbers don't lie and if you want the specifics on how we got those numbers e-mail me and will give you my engine builders phone # and I'm sure he would be more than happy to explain exactly what he did.

 

Nah, I've seen more than enough from people. Not trying to start another internet fight, but stuff like this doesnt do much other than help other people BS about flow numbers, as if it werent bad enough. I'm not saying you're being dishonest or anything, but I know I'm not the only one who knows an LT1 casting cannot be made to peak over 300cfm at 28" depression as-cast.

You can make over 600hp NA with that much air... so good luck with everything

 

Here is my preliminary flow sheet where the heads are flowing 298@.700, but my engine builder has since fine tuned them more and got the numbers to what I posted above. I will add the flow sheet when he sends it to me--which should be by the end of this week. Skarodom you can take it with a grain of salt, but I have no reason to lie.



Flow Numbers

 

I dont think anyone implied you are lying. However there is simply not that much material to remove via porting and get those numbers, without bench tricks. Were those a 1993 casting?

 

You say I am not a liar but that is exactly what your insinuating. They are an early casting of the Lt1 heads (92 and up) I don't know the specific year they were produced (Casting Number -10128374). Your right there is not much material on the short side radius, but there is room elsewhere. He even said that with more time with the heads he could get them to flow another 10cfm. If you guys believe that you have found the absolute limit to an lt1 head than it's your loss. You know maybe just maybe sombody can port a head better than you. I don't want to get into a long drawn out fight so i guess will just leave it at the fact we agree to disagree.

 

No, it's being insinuated that you're simply being misled, not that you're a liar. You're the customer, you arent supposed to know this stuff offhand. Someone else already has your money, so it doesnt do anyone any good to start arguments. You posted your numbers with a question, and the bottom line is that on a superflow bench at 28" depression, those castings simply do not have enough material to literally make the hole that large. We're just talking SBC, nothing special. Even ignoring the area over the short side, if you only consider the area at the pushrod, you cannot get the crossectional out of that straight section (I use this example because skill has less to do with that area when shape and efficiency comes into play) to flow anywhere near that. Its not magic, people dont just pull 20cfm out of their asses, it's an exact science, and 300cfm wont go through that hole at 28". As far as how "good" one person is or another... There ARE a few people who can do better than we can, but you know what? None that I've come across will deal with the public. How about guys like Greg Good, or our local Chuck Riddeck? Greg is down in TX, taught the SAM cylinder head course for awhile, and now is back doing ProStock/fuel/etc. cylinder heads. He's about as close to a guru as anyone, the guy is absolutely amazing, one of the best few in the world... and even he doesn't claim any more than 280-285 peak with these castings. Chuck did a 300cfm set of LT1's.. .of course that entailed adding ALOT of material to them, along with revised valve angles (which in itself is an extremely time consuming task).

You don't seem to understand that probably 90% of auto shops lie or mislead people. Noone's calling you a liar, and you can put your head in the sand and pretend your guy is right and that's all there is to it. If I spent much $ with people I'd certainly want to believe them too. The bottom line however is that with the previously outlined conditions, an LT1 casting does not have the physical capacity to be opened up that much, much less ~315?!

Have someone else flow them... see what they say.

Hope it works well for you

-Phil

 

*chuckles at people not grasping basic concepts*

 

Who?

Never say something is impossible. Someone will always prove you wrong.