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

 

You can always have your porter mill the heads to get a better compression ratio. From what I've read, the chambers basically take away a full point in compression, leaving you with 9.5:1 compared to the stock 10.5:1. You can always raise that though like I said by milling the heads, and/or getting a thinner head gasket.

 

A thinner gasket like the Mr. Gasket .026 one should put you somewhere near 10:1 the b-body got the same exact bottomend but with iron heads "speced at 64cc" and a .029 gasket and were 10:1 stock.

The aluminum head motors were roughly 58cc but with a .049 gasket which ended up around 10.4.

 

That's a great idea as it will also drastically reduce your quench, thinner head gasket with milling of the heads a slight ammount will let you run more compression than the stock 10.4 while having less chance for knock than stock.

 

Thing is stock the pistons are too far in the hole to get that good a quench most numbers I have seen trown around put them at like .015-.020 down stay on the lowend with the .015 plus the .026 gasket gets you .041 which is OK but not great certainly better than stock though. I don't know all the details but I would think by the time you mill the hell out of the trickflows enough to get a signifigant compression bump you are probably going to have to add intake milling to your list of needs.

 

0.041 quench is a whole lot better than the 0.064 quench stock, all the stuff i've read says to aim for 0.035 quench to account for rod stretch, tolerances and whatnot. i'd think that 0.041 quench vs 0.064 would be a worthwhile goal to try to achieve, It will save him some milling on the heads and improve quench.

 

Thanks for the info guys.

But in general, lets say I don't mill them down much. How much power is lost from the compression decrease? Is there a formula out there that I can try to figure out or a rule of thumb?

Mike

 

If you reread my posts your compression loss will be very minimal we are talking .3-.4, but you will be increasing flow, too many variables there to offer a formula. IMO though with a cam large enough to make them work I think it is going to get lazy down low between the larger ports and slightly lower compression.

 

Kool not bad. Thanks for all the help folks.

I'll let you know how it all works out.

It's going to have a 4,000 stall in it so it won't worry to much about lower rpm power. But I figured that was going to happen.

Mike

 

I would advise against milling the heads in case you ever decide to go with a blower or turbo. You will need the additional CCs in your heads to help reduce compression, if you go F.I.

I would use the .026 Impala head gasket and call it good. Factory quench is around .064; with the Impy gasket, you will get down to around .041-.046 (you would have to measure how far your piston sits in the hole at TDC to be certain).

With the pistons in the hole .015, that will put you at 10.2 to 1; at .020 yuo're at 10.1 to 1. The minor loss in compression a very small price to pay for better flowing heads.

Why did you choose the Trick Flows? The Lloyd Elloit heads are much better IMHO.
http://www.eportworks.com/Products.htm

 

I choose the trickflow because I wanted to try somthing different. Plus I know they can be taken further then stock heads.

Mike

 

I haven't seen the flow numbers on a set of hogged out Trick Flows.