Are the combustion chambers on AFR heads pretty similar to stock or will we see a specific piston design from Diamond, JE, etc. ???

I hear that Ed Curtis has a set of the heads, what's the word Ed?

 

Ed, allow me....(You owe me one now)

The combustion chamber design of the new AFR heads is definately different than stock. There is less "dead space" behind the valves which makes for a much more efficient chamber and creates a "double quench pad" as well.

With most LS based configurations running flat top or dished pistons anyway, its really not an issue at all, however, if you are trying to build a max effort high compression motor and needed a small dome on the piston, it would definately be a situation where a custom piston would have to be made. I'm sure in the next few months we will have the oppurtunity to get a casting out to the larger piston manufacturers so they can digitize the chamber and make the appropriate dome configurations. Don't forget, you can always run the flat top and mill the chamber volume lower for the additional compression as well.

Hope this helps you out...

Tony M.

PS Another big plus to our chamber design is the fact that an AFR headed motor would have about .030 additional piston to valve clearance compared to a stock cylinder head at the same chamber volume. (NOT A WELDED STOCKER!)

 

That's exactly the sort of info us in the aftermarket really need to know about! Thanks!

 

I agree, thanks for the info Tony. I'm pretty anctious to see these on the market.

Rob

 

I can see the nest wave of huge cams on the way. The t-Rex will be a everyday cam pretty soon. An extra .030 will allow for bigger cam w/o flycutting.
YEA............

 

I'm looking forward to some independant dyno tests on these heads for sure. It looks like there might be some 225's in my future

 

Thanks for the update Tony!

How soon could we see that info get to a company like say Diamond Pistons?

 

tony is there a possibility of getting 15 to 1 with a flatop with an afr head?

this there enuff material to do that?

 

Or 13:1 or 14:1 with a flattop thanks!

 

PSJ...

Our primary goal right now is to try and accomodate as many of you guys as possible....when the smoke clears and we start catching up, we will send some castings out to the various manufacturers (Diamond, JE etc.) More than likely by they than they would have had the chance to see our heads when a customer sends one to them for a custom application, but any who still needed a casting at that point in time will be handled.

Z28....

In regards to compression ratio, I probably wouldn't take our castings any lower than 56 cc's or so (about an .060 flatmill). More than that would start screwing up intake geometry and definately hurt the flow potential of the cylinder head. Assuming 56 cc's, a stock shortblock would come in at exactly 12 to 1, and with a 10 cc dome, a custom piston would yeild 14 to 1 (You would need a 14 cc dome to achieve 15 to 1....too much dome in my opinion....it would really make a mess of flame travel assuming you could even build a piston with that much dome volume). I would recommend a slightly more conservative 14 to 1 which would make for a much more user friendly overall combination and still have the ability to put up some serious numbers with the right camshaft and a good flowing pair of cylinder heads.

Thanks,
Tony M.

 

OR for high compression just add more cubes and keep flat tops.

 

Tony thank you for your quick response

I would like to stay away from a large dome also, I may be stuck with 14 to 1 due to the fact the bore size will be small, since I am staying with a stock bore to run in the factory stock class.

 

Tony, Just curious... do you have flow/dyno numbers for the "as cast" versions of your heads??

 

Tony, what do you think is the max compression ratio for the street and 93 octane for the AFR's? Assuming cam with some overlap to bleed of compression at low rpm, 4.10's and good tuning? I was thinking the new chamber design might allow that to creep up a little more.

Thanks

Wade

 

There is a dyno test on their site http://www.airflowresearch.com/dyno/ls1_030804.htm
pretty weak though I think since between the stock head test and the AFR test they also changed the cam, intake and TB

 

thanks for the info Tony, can't wait to see some of the future combos

 

Yes....I'm sure everyone that bolts in a MILD street cam, heads, and an intake picks up over 100 HP.....what was I thinking. If I had to take an average, I would say similar combination I've seen would make somewhere in the low 400's @ the wheel. I've seen some higher and I've seen some lower, but my best guess from all the input on the various forums would be 410-420 @ the wheel. We will see in the next few weeks what my 2000 coupe does with the exact same combination featured on our website. I will be testing the finished product on two chassis dynos just to confirm the accuracy of our results.

Moving right along....in regards to the "As Cast" flow numbers and availability, don't hold your breath. They are a LONG way off....we are focusing all our efforts and time on trying to bring to market all of the CNC versions of our new heads. Eventually, the "semi CNC ported" stuff will be completed and I will keep you guys up to speed on their final flow data as well as availability, but they are definately 4-6 months out.

Mr. Blackbird....you bring up a good point about the compression ratio the new heads might tolerate on pump fuel. I would say with 93 octane and an aftermarket camshaft, 11 to 1 would be fairly safe, and that number might even be able to be tweaked a bit higher, especially in cooler climates with the right tune. I do think the new chamber design will allow higher levels of compression before detonation sets in. Look forward to seeing real world results and not speculating...I might flatmill the 205's destined for my car a few cc's and see if I can get away with 11 to 1 out here in CA where the highest octane available at the pumps is 91. I think I will be able to get away with it seeing how even GM raised the bar a notch on the LS2 engine in the C6.

Catch you guys again soon...

Tony M.

 

Tony, something I was noticing on your Dyno graph that you had posted. It says you added AFR heads, a cam, LSX intake. But the before dyno says stock heads and it made 428 hp. Was this with the cam and LSX and all you did was add the AFR heads and picked up 102 hp with just heads? Or you picked up 102 with the heads/cam/LSX? Also if the before number is without the cam, how did you make 428 hp with bolt-ons. Just curious is all.

Thanks,
Dave

 

The engine had headers on it for the baseline test along with an electric waterpump and maybe an alternator. Between the freed up power from basically no accesories and the headers 428hp sounds about right.

The AFR combo test added heads, cam, and intake on top of the baseline motor.

 

Tony M, did you have a response regarding high compression flattops, what would work? I am getting bombarded by folks asking me this. Any generalizations to share?