Hey guys, I will be buying AFR heads for my 350. I have a few questions about which to choose. I have a GM PP crate engine 350-300HP. Cam is 212/222. Currently I have a 9.1 to 1 compression ratio. I will be using a LT1 intake. I desire horsepower in the 350 - 380(oneday) range. I am not making an all out race car. My question is first, 180cc intake ports or 195cc. Second 68cc combustion chambers or 72cc. Third, if I machine the heads to lower the combustion chamber cc's, how low do I go? Who has the best prices? My last question is whats the difference between the TPIS AFR heads and AFR heads?

I have read several threads related to this but I don't seem to have all the info. I did read the thread on TPIS AFR heads. I understand that the guy's machinist believed their port work left a lot to be desired. IMOP, most machinists have problems with other peoples work, bottom line.

This is a thread on AFR heads. I want these heads. I don't wan't any other heads. Please keep to the topic of AFR heads. All advice, constructive, is welcome.

This is not a thread on bashing TPIS. If you don't like them, fine. Please don't post negative comments. Please give me constructive advice to help guide my selection.

 

If you're going to be using an LT1 intake, you definately want the 195 cc runners. The short runner high volume nature of the LT1 intake will take full advantage of these. The only reason to go with the 180 cc ones is if you're using a LTR setup and want to maintain the velocity of the intake charge.

What's the combustion chamber size on your current heads? We need this to let you know what your new compression ratio would be with the 68 or 72 cc AFR's. If you want to mill these down that needs to be taken into account too. Basically the smaller the combustion chamber the higher the compression ratio. The best thing to do is to figure out what c/r you want and then work backwards to figure out what size c/c heads you need to achieve that. I wouldn't go over 10.5:1 on a daily driven street motor. And if you ever plan on forced induction you probably don't even want to go that high.

 

Thanks for the reply Scott. I have currently have iron L98 heads(64cc). As for compression ratio, I'm not sure what I want. I don't know what would be best. I do know that too much compression will give me denotation on pump gas. I also know that aluminum heads have less denotation with higher compression. Outside that, I just want more power and to go faster. Maybe one day I would supercharge it, maybe not(That's a lot of $$ and I've got other things to do.) I want it to be driveable, but I drive the car maybe 5,000 miles a year. Thanks again.

 

I have that same engine still waiting to be swapped from my wrecked 84 Bird to my 87 T/A TPI. I'm gonna be running the Stealth Ram though. You definetly wanna stick with a 64cc head otherwise your compression ratio will drop.

 

Keep the compression ratio at upper 9s or low 10s. This will work with pump gas very well, especially with aluminum heads.

As for the AFR, I agree with Scott on using 195cc heads, they will work great with the LT1 intake.

enjoy.

 

OK if you have 64 cc heads right now, then the 72 cc AFR's would drop your c/r to 8.4:1 (horrible for NA but good for forced induction), and the 68 cc AFR's would make it a 8.7:1 which is still low for NA. You can run much higher compression than this safely.

I would definately reccomend milling the 68 cc heads down to at least 64 cc to get back to the 9.1:1 c/r you currently have. If you wanted to go to 10:1 you'd have to have a 56 cc head, which is a lot of milling. A 60 cc head would give you a 9.5:1 c/r which is pretty good.

Regardless though, you really need to take the heads to a reputable machine shop to have the work done, because as you mill the heads the valves will get closer and closer to the pistons, so there is a limit to what you can do. HTH.

 

Thanks for all the help guys. I have been leaning towards the 195cc's myself. Thanks for the milling advice. I was thinking 60cc combustion chambers sound right. I just hate taking crap to any machine shop. They, or any other shop, always seem to have their own idea of whats best for you and your car. I hate not having control over the process, I.E. they machine the heads.

Has anyone used the TPIS heads. I see on their site that they are worked to 187cc Intake and milled to 54cc Combustion. They already come pre-ported. I know their $1850.00, but I don't have to dick with a machinist. The heads are already worked, so its power out of the box.

I am aware that most people here do not like TPIS. I have had no problems with them. My thought is, I can get a quality product for less money and stess than getting a street head, having it machined and ported.

What do ya think?? Keep it positive, no bashing TPIS.

 

The best thing to do is find the flow of each head. I think for the price, AFR would still be cheaper even after getting it milled down. The only thing you need to figure out is which one flows better with your intake.

187cc doesn't sound big enough for your intake, so I personally wouldn't do it.

TPIS is too expensive for the products they put out. These guys will be cheaper and they are better in my experience than TPIS.
GTP Racing
They quoted me $1600 for a full port, bench flow, valves, springs, clips, and retainers on L98 aluminum heads. Once the heads were done they flow:
243/190 @ .500
246/200 @ .650

That was not bashing TPIS, just telling the truth.

 

I've never had any dealings with TPIS, so I can't advise you one way or the other there. But they've been around a long time, so they have to be doing something right at least.

Anyway, it's been a while since I've looked at what AFR's cost, but I'm guessing it's at least $1,200. So $650 for the porting and milling that TPIS is doing doesn't sound too bad.

But like Maroon said, I try and get flow numbers for the heads and compare, as well as making sure that the heads will fit your engine with no complications (I'm talking valve clearance here). I would also reccommend getting quotes from a few machine shops to see what they'd charge for similar work.

And the 187 cc runners will limit your power some, but they'll still be plenty capable.

 

Order them already milled straight from AFR.
About $250, angle milled w/ intake and holes cut too.
Best way to do it.

Marooned, out of the box AFR's will beat those numbers and cost 1275 plus shipping.

 

Ok one thing to remember on the AFR's is that the 64cc Chamber is a closed chamber and a Tech at AFR said if I ever plan to mill the head to adjust compression that you can't do much with the 64cc Heads. He Recomended the 195s with 72cc chambers for the availabilty for later upgrades. Also if you order them directly form AFR you can Specify you want the 195s with 72cc chambers and tell them what you want them milled to and they can Mill them to I think 58cc. Just get the 72cc chambers Milled to Like 64cc and Later on if you Change to forged pistions and the compression chamber is different you have the option of Milling more to adjust the compression. This is just a reideration of Z69 post also

Call AFR and Verify Don't take My word but I know the 64cc chamber is a Closed chamber. I myself Would perferr the 72cc For Flexability on I can take them where I need them. It may cost a little more up front but that is better than costing a lot more to replace a $1300+ Dollar set of heads later.

Just my .02

 

I am going the same route and have spoken to AFR more than a few times. I ordered the 195's and LT1intake is converting mine right now. If you are going to any forced induction then AFR recommends the 72cc chambers and no milling otherwise they recommend the 68cc chambers. As far as I know there is no issue or difference in the chambers other than the size so either can be milled but I did not ask them. With 3/4 inch thick decks there should be no issue milling either head them as much as you want. Angle milling would be the way to go. With the aluminum heads you can run up to a full point higher on the compression. Note on any dyno tests that AFR has posted the do not run more than 9.5CR. This may be due to the fast burn design and limiting the detonation possibilities.

 

I've got a set of AFR 195's I will be selling. Fully ported to better than their CNC heads. No miles since new Serdi Valve job, could easily run your cam. Drop on some rockers and your good to go. Hit me up on PM if you want to save some money.

 

Thanks for clearing up a few issues for me fellas. I am going to call AFR first thing Monday morning. Sounds like this could be easier than I had feared. Great input!:yourock: I'll keep ya posted.

 

Just ordered my heads from AFR. Spoke to Dave. He got me straightened up. I ordered the heads, angle milled by them. I expect to see them by Christmas They said it would be 6 to 8 weeks before I see them. By then I will have forgotten I ordered them. What a surprize it will be when I open them up. Thanks to all who responded esp. Z69. Boy, if I only had called AFR to begin with I could have saved some time and energy.

:yourock: