NeedStangSpeed

Does anybody have these heads or know the specs on these? Like:

Whats the size on the intake/ exhaust valves
What size bore on the block would you have to go with to run these heads?
Combustion chamber size?
Intake/ exhaust runner size?
Max valve lift? I know this will depend on the springs.

Just doing a comparison between the Trick Flows, Patriot Performance, and the MMR stage III heads. Trying to figure out which is the best for the money.

tbirdscwd

Once "Stage 3" is put in front of PI heads........you are better off just going with trick flows IMO. I don't know the diameter of the valves, but if they are anything over .5mm larger they will likely require at least a .020" overbore like is required by the patriots. You are correct in that the max valve lift is dependent on the choice of valve springs. You will need to contact MMR for flow numbers on their heads. I don't think they post them publicly. Chamber size is likely at least 46cc for a heavily ported PI head without any shaving

NeedStangSpeed

Well that's the reason I was looking into this. My only hang up with deciding right now is the fact that I don't understand why Trick Flow would make such a high dollar head, which I know is better in design, but only puts a 1.84" intake valve in it and a 1.45" exhaust valve. You'd think they try to get a 2.02" intake valve and a 1.60" exhaust valve. The 185CC 5.0 heads made by Trick Flow offer's the bigger valves. Is the 5.0 bore really so much bigger than the 4.6? This is just what makes me wonder if they are really worth the extra $600? Even between the Trick Flow and Patriot there is only a 5CC intake runner size difference. So I guess the major question is this, what is that much better about the Trick Flows to justify the cost?

As far as contacting MMR, I have already emailed them, just waiting for reply.

tbirdscwd

The trick flows are arch better design. Thicker deck, longer threaded park plig holes, relocated intake valve which improves flow and efficiency, redesigned combustion chamber which withstands more timing and less likely to see detonation, increased piston to valve clearance (no need for piston notching), improved fuel efficiency, and they do this right out of the box. They also come with much better guides, retainers, keepers, etc...

As far as valve size, they simply do not need anything near a 2.02" valve to maximize power output on a 281 ci engine. With a 350+ cubic inch small block with significantly larger diameter pistons, larger valves can be beneficial. Remember that the larger the diameter of a single valve, the more low to mid range power is sacrificed for top end. Trick flow does have a more aggressive set of heads in the works using a 1.94" intake valve from what I hear, but I don't know how much that is really going to help seeing as how the current heads will rev to like 9,000 right out of the box.

As for intake runner size being similar on the stage 3 mmr, that really doesn't mean much. The trick flows have a lot more direct shot on the intake side and flow a hell of a lot more air than even the best ported PI heads

NeedStangSpeed

Ok, didn't really look at the diameter of the intake valve in that way, but totally makes sense to me now that you made me think of it. So, you can run even a stage III cam with flat top pistons and not have any PTV clearance problems? That I did not know. It does seem that they are worth the extra $600 though. Thanks for the info. I know there are other threads on these forums about the heads but none really answered those questions as far as I could see.

97stanger

I am running the stage III MMR's on my new build

NeedStangSpeed

How do you feel about them/ like them? Also do you have the specs on them?

tbirdscwd

I am not aware of a set of cams that would have any ptv issues with the TFS heads. You gain quite a bit of clearance thanks to the relocated intake valve. You can get away with a "Stage 3" level cam on a ported PI head, but it will require you to notch the pistons no matter what the dish size. The ptv issues these cars have with the stock heads is actually out on the outer edge of the pistons right above the ring lands almost, so it really doesn't matter what size dish they are, they will still have roughly the same clearance if they are not notched.

NeedStangSpeed

Thanks for the info, I really appricate it. I'm kind of working backwards this time with a mustang. Going to build a motor, get all the bolt on's and then get the car. Hopefully I can stick to this plan, lol. Sometimes I get ahead of myself and get the car, which leads to less money to build it up.

What effects will the 38 CC heads have with flat top pistons, or should I go with the 44 CC heads? I know I am going N/A with the build, and am not running nitrous. I just know they rate the 38 CC with about 15 more HP, and would like to squeeze any little bit like that I can into it since they seem to be the same price. Plan on running a stock crank (because I know I'm not getting anywhere near 500HP, which I know they are good for about 600HP) but get forged pistons and rods. Still deciding on the rest of the top end though, thinking about the track heat intake, and putting the oval port Accufab TB on it, but all that is still up in the air yet, got to figure out the longblock first and go from there.