OK I ordered a set of them new trickflow heads from summit. And I am going to send them out for a full port job shortly after I recieve them.

My question is this.... They are 62cc combustion chamers. And I would like to know what will my new compression ratio end up if I slap them on new but stock internal lt1? Will I loose quite a bit of power from the compression loss?

Mike

 

Going from 54 to 62cc will drop you almost a full point of compresssion. You could always have the heads milled while they are at the shop being ported...

 

If you go to a thinner gasket like say the Mr. Gasket .026 one you would end up near the stock b-body compression of 10:1 we do OK at that but we do it with iron heads, aluminum needs more compression to equal irons power due to thermal issues, thig is these same thermal problems are what allows aluminum to run more compression. Which comes out on top after all that has been and will be a bench racing argumen for decades. In the interest of simplicity here though we will call it a wash.

Though reallu had you read the description Trickflow themselves doesn't even recommend these for an NA 350. You give it enough cam to allow it to use those large ports and you might not be disappointed BUT it is still a mistake, especially since by the time you have enough cam to try to use those heads it will want more compression not less to help lowend throttle response. If you plan on forced induction or a stroker like Trickflow recommends then by all means be a guinneu pig and try them on the NA 350 first.
AI has them on their site ported and assembled for a suprizingly good price http://advancedinduction.com/AiProductsTFSAFRLTx.html Not that I am recommending this but seems to me this would be cheaper than buying from Summit then sending out for porting.

 

I would definitely have them milled down if FI wasn't in your future. If you're having port work done anyway, then milling would be no problem IMHO. If you're gonna be doing bottom end work, then let your piston choice dictate your final CR.

 

WHen I looked at TFS with Lloyd helping me he wished for to have them milled ALOT, but he ended up recommending LT4 heads but the funds werent there to pay 1400 for heads for him to rework them and since I have decent ported heads. I just went with a bret bauer cam.

TFS are for blower cars or if you have a 383 with flat top pistons and you need to get the comp down a little. Otherwise your going to loose power compared to a higher comp n/a set up. Its compression that makes power.