afr's 185 58cc or 61cc

[D's 91 stang gt]

i'm going to be getting theses pretty soon to go with the 331 stroker that I'm going to build but I was wonding what the difference is with the 58cc and 61cc heads

 

[maverick0716]

The numbers refer to the size of the combustion chamber. Going with the smaller number will raise your compression ratio more. Stock 5.0. HO motors have a compression ratio of 9.0:1. So they might raise the compression to around 9.4:1 or so.

 

[D's 91 stang gt]

thanks so if I wwnt with the 61cc which are a little cheaper this will be fine with the setup i'm building correct? even if I add a turbo a year down the road

 

[maverick0716]

I don't know about turbo's, but I know with superchargers it's a good idea not to get a low cc head, because your compression will be too high for boost. I think you made the right choice if forced induction is in your future.

Maybe someone who knows more about forced induction can chime in.

 

[D's 91 stang gt]

great I'll go with the 61cc another question is what stroker assembly shoud i go with I was leaning towards scat because but dss and chp offers goods kits for the money what do you guys suggest?

 

[myshifter]

well there is alot of things to factor in when buying parts in regards to compression ratio. Piston height, how far is the piston in the hole at TDC, compressed gasket thickness, what type of piston, flat top with valve reliefs? You need to know the volume of the valve reliefs, etc.. As far as buying a kit, almost all kits need to be balanced and if used with scat or eagle parts almost always the rods need to be resized as they are typically too tight especially the small end. Lots to decide before you jump in with both feet

 

[1991vert]

just remember with the rotating assembly...you get what you pay for

 

[Daggar]

You may want to check into the burn characteristics for each head before you jump out and buy 61cc chambers. The word is that the burn and quench for the AFR 185 heads are considerably better with the 58cc chambers. Hit up Rick91GT for more info on that.

 

[Pennywise2]

just remember with the rotating assembly...you get what you pay for

That is true if I ever heard it!

 

[rd]

I just did this, and decided on the 58 cc chambers. Most of my experience has been with 68 to 79 blocks. In spite of published numbers, both of my rebuilds calculated out to about 8.5 to barely 9.1 compression, due to the conservative nature of replacement pistons, and the deck height tolerance on the blocks. Even with the iron GT40 heads at 64 cc or less there just is not much compression.

So I decided that the smaller chambers would provide some compression, getting up to 9.2 or so.

If you are not going to add a blower, I would put as much compression in there as you can, up to 9.8 to 1 or so. If it detonates, you can reduce the timing for daily driving, and put better gas in when you want to hammer it.

For a NA car, I would go with the small chambers.

 

[FORCED2DV8]

I agree, If you going N/A. If you are going to use a turbo or blower soon, then get the larger chambers, as they will allow you to run more boost.

 

[Foxfan88]

lets not forgot if u bump compression, plan on running premium gas all the time.

 

[88Stang331]

I have the 64cc TFS T/W 185 CNC heads. I plan on going with a hellion turbo kit later on on my dart short block i'll be building probably beginning of next year.

Lower the compression = more boost you can run

 

[Rick 91GT]

The 58cc and the 61cc have a different chamber design, one is open, one is closed. Get the 58cc....

Boost is relative remember that.... You do not need low compression to run a lot of boost, even on pump gas. There are a lot of design variables to consider. Pistons design, chamber design, cam timing, etc...

:OT: Rich I tried you back a few times last night but kept getting a busy signal, I'll try later tonight.