from what I can tell there is not really much difference (besides price)
am i missing something? with plans to have a set ported it seems like GM LT4s would be a better value...

anyone agree or disagree...

 

I do not have the gm flow numbers, but i am assuming that the AFRs flow alooot more than the gm ones.

 

I dunno. I think the AFR's would be better and have more room to grow.

 

Here are some flow numbers from my LT 4 heads.

GM LT4 Numbers

Lift stock ported % change
0.050 43 49 13.95
0.100 74 80 8.10
0.150 107 115 7.47
0.200 135 145 7.40
0.250 158 174 10.12
0.300 180 196 8.88
0.350 198 217 9.60
0.400 212 234 10.37
0.450 227 254 14.00
0.500 230 266 15.65
0.550 222 272 22.50
0.600 274
0.650 271

Hope those help.

 

http://airflowresearch.com/pages/180sbc_lt1.htm
http://airflowresearch.com/pages/195sbc_lt4.htm
If you scroll down you can see the flow numbers for the AFR's. Im assuming those are intake numbers and you can compare them to the AFR and see the AFR lt4 heads flow better and leave you plenty of room to grow if you do want to send them out to get ported.

 

See there is the problem people ASSume AFRs are good heads despite evidence and results to the contrary specifically with their smaller castings like these.

 

imho don't mess with the 195..either go to the 210s or the gm lt4s. I'm using the gm lt4s.

 

I wouldnt put either an out of the box GM LT4 head or a 195 AFR CNC head on. They dont make the greatest numbers unless they are ported by a reputable porter. I would look at which ever head you can get a raw casting of cheapests, and then have someone port them. If you go FI down the road, the AFR's will best bst due to larger combustion chambers and thicker deck.

 

I plan on keeping it N/A.. which is another reason I am leaning toward the GM LT4's... they have the smallest combustion chamber size (54cc) , therfore will keep the compression higher, so more power it seems like it would be easier to open them up more if the need arises, then to make 62 cc + smaller. and I can use a "flat top" piston instead of a domed design. I am thinking 11.1 -11.5 compression would be reasonable.

 

$30 to deck the AFR's will get you to whatever cc you want...no need to change pistons

 

Nope, it's not that easy, you can't just deck them to whatever you want.

The LT4 casting is better due to the smaller chamber, the much better cooling, lighter weight and you can still get some good numbers out of them. You will need larger seats if you put a big valve in there, that's about the only drawback.

The fact that they allow a lot more compression is key, the better cooling passages allow you to run more compression as well without issues.

Bret

 

OK, so how is it that people are running AFR's with 56cc chambers? My point was pistons wouldnt need to be changed, and that the heads could be in order to raise the combustion.

 

You have to really mill them and you can't shape the chamber correctly when they are really small. The best AFR's i've had in the shop are a bare to get down to the high 50's.

All depends on the head porter though. Yes you can get the chambers down there, but the LT4's are already small and you can get them REALLY small.

Bret

 

Okay, I wasnt aware of that. Thanks for the info.

 

Not gettin on your case, but the LT4's are a better head overall, you can't do as much with the port since there is less material but if you can get the LT4's for a good price you can make good power with them if you exploit what they can do better. (cooling and compression)

Bret