well tonight i just checked how many cc the chamber is in my Gt-40's to find out for myself instead of the internet guessing game. and then i checked the E7's and if this is true i really really got lucky with my Gt-40's
E7 total of 75cc
GT-40's 64cc's
im guessing a weekend job to change heads on my mustang and then i should have more hp.
does anyone know how much that will bump up the compression?
You sure about those E7s ????? I thought they were around 65cc as well...
E7TE heads are 63cc ;) and GT40heads are 65.5cc
if you need more info to prove that the E7TE heads are 63cc.. the stock replacement piston for an HO motor is TRW L2488F..stock comprestion ratio on an HO motor is 8.9to1
http://store.summitracing.com/default.asp?target=eProduct.asp&N=120+400220+301942&Nao=140 (http://store.summitracing.com/default.asp?target=eProduct.asp&N=120+400220+301942&Nao=140)
this should help.. but i don't know where summit got there spec's maybe from a new revised speed pro catalog i wish i had the old TRW catalog form when TRW first made these pistons.. the spec's shown for the deck height 8.229 should be for deck height 8.206..
but they are corect about when the 8.229 deck height blocks was used from ford and that was from a short time of 1973-1976...
ford 289 engines and 302 non HO motors used TRW L2482F pistons which has as a comprestion ratio of 8.0-8.5to1 which used a deck height of 8.206..
beleave it or not with GT40 heads you will lower the stock comprestion ratio to about 8.8 or 8.7to1.. but flow twice as good as stock E7TE heads out of the box.. and allso have larger valves.. E7TE heads have 1.78 intake valves & 1.48 exahust valves GT40 heads have 1.84 intake valves & 1.54 exahust valves..
http://www.jason.fletcher.net/tech/flowdata/castiron.htm (http://www.jason.fletcher.net/tech/flowdata/castiron.htm)
hope this helps..
Nick
i could be wrong with the E7's BUt if they are that close then how do you get more power from them . bc they flow beter.
oh yeah i hear the only difference between the gt40's on cobras as to exploders and lightnings were that they decked em to bump up some hp ? if so mine were decked not sure how much though. . oh well im in no rush to put them on bc i would like to get some more go fast goodies and do it at once
nope they flow better because the intake runners and exahust runners are made larger and the valves are larger..
thats what makes more horse power..
and as far as the new GT40 heads their not has good as the old ones.. the old ones had like i said 1.84 in 1.54 ex valves.. the new GT40 heads which are based on the new style exploders..they do have the 1.84intake valves but only have 1.48exhust valves..
If you really want a good head comparison, check out MM&FFs test results on a 306 from a year or two ago, they broke it down into 3 catagories based on intake runner volumes. you can find combustion chamber size, flow numbers hp and tq graphs on that particular motor, ect. they from the GT40s all the way up to the AFRs. I'll dig it up if anybody wants