add a dry sump. We have seen a fair number of LS3s go bang this spring and late last year on the race tracks High speed left hand corners and hard hard braking causing the oil to pool on the right side of the block or up in the heads.

Even in straight line performance an LS6 was quicker off the line or out of corners. at about 80 mph the LS3s extra ponies would over take the LS6.

 

to mu understanding the one head that GM did approve of was reworked by LPE for Speed World Challenge

LS6 SWGT
LS6
runner 240
chamber 60.9

Intake
Lift Flow
.200 150
.300 225
.400 273
.500 291
.550 304
.600 311



Exhaust
Lift Flow
.200 117
.300 168
.400 202
.500 217
.550 221
.600 222

 

From what I can tell, the OP really was about 'Bang for the buck'. That said....

I do think the AFR's are the best heads for making power here but if you've got two identical Corvettes with the same supporting mods (LT's, Exhaust, Intake, Cam, fuel, etc) and you put AFR's on one car and put a set of Stage 2.5 Patriot or MTI heads on the other, I don't think you're going to see a huge difference in power, at least not for the price. The AFR's will make the most power but, if this is about 'Bang for the Buck', I'd save the extra money and just port the stock ones. They'll flow 300 @ 600 lift, which is more than good enough for a street car.

 

Trust me in most cases they will not perform the same (Ive done the dyno testing) and a ported OEM head will NEVER have the low end response (especially part throttle) that an AFR will have. Proof in point is look at the bulk of the independent dyno results with some of the less expensive ported OEM casting....completely hit and miss even when discussing the same manufacturer. Most of the AFR installs perform above average, with some well above average that took the time to dial in their combo.

Also, re-read most of the points I was trying to make about an efficient head (small runner/high flow).....you will never get the same benefits from an OEM head 25-30 cc's larger (thats a huge difference in port volume and subsequent air speed.....a much smaller port with similar flow achieves that accomplishment because its simply a much better designed runner and the only way it can flow the same as a larger port is to move the air thru it with more velocity due to its superior shape/design....and velocity improves cylinder fill and scavenging).

All that said, if your on a budget and the perks I mention about having a very optimized head arent that important to you, and you dont really want to pay for the extra 10-15 peak ponies an AFR head is also likely to give you, a properly ported stocker can perform but for those looking for optimal results with all the other nice perks I mentioned, the AFR's really deliver and most of the people that "get it" are the customers that stepped up and purchased them.

Also....with the multitude of AFR heads on the market, how many dissatisfied customers have you seen? And how many people that went another direction regretted their decision only to do it all over again (trust me thats a long line). In the end their budget head cost them alot more than having done it right the first time. Some people post and talk about it but some would rather spare themselves the drama.

Hopefully Ive given some of you a different perspective on your cylinder head purchase....its an area that it always pays to buy the best you can. Think about all the other costs involved in the swap.....saving a few hundred dollars, even $500 isn't worth giving up all the perk I highlighted, extra power, better resale value, and stellar customer support both before and after the sale. Personally, I think it makes more sense to save a little longer if need by but thats just my opinion.

Feel free to contact me directly guys if you have any more questions....

Cheers,
Tony

 

You really get what you pay for when it comes to cylinder heads. AFR's are top notch. Were using the 225's on our 8 second racecar and they get the job done

Seth

 

I have so far run three different heads on my car (including the stock 241's), the latest being AFR's that were carefully prepared with an 11.3 CR and a small cam (AFR6016 - 224/228). My goal was not to set a peak hp record with some big *** cam that sounds cool and doesn't perform well, especially on the street. I wanted something that would "snap" you in the driver's seat and pull hard through redline. I finally got this response from the car with my current setup. It just flat out rocks.

I previously had a set of Dart heads, which I have seen some call the ultimate 243 design. I was saving for AFR's when the Darts first came out and for the price at the time they seemed to be a reasonable trade-off of perhaps a few hp for the cost savings and the advertised flow numbers were nearly the same. What happened? I ended up disappointed that I went through all that work (and to properly set up a set of heads and the valve train it is a lot of work) and ultimately realized I had settled on a set of heads I knew up front wouldn't perform as well to save a few bucks. So while the Dart heads performed much better than the stock 241's, the AFR's blew them away on the new setup. In comparison, the advertised flow numbers on the Darts were close to the AFR's so flow numbers are not the parameter from which to pick a head in my opinion. You need to look at installed results from the guys that are using them and what their dyno curves look like because just providing a peak number doesn't mean much, you need to look at the whole curve and in my case low to mid RPM because that is where I typically run my car. I don't want to trade a soft mid-range for a peak number.

 

This thread has some great information!

 

Sure does huh. Has me thinking about what direction I am going over the next couple of years with the car. I did see mention of long tube headers though. I don't know of any CARB long tubes and I believe the op is in California too.

 

you're correct, Long Tube Headers and California Smog Approved can't be used in the same sentence.