Is it worth the trouble for higher compression
Is it worth the trouble for higher compression I've been reading about compression and milling the heads and so on. I've read that you shouldn't go below 55cc-56cc after that a lot of things can go wrong. I can't really find a answer to my question.
I have a 5.3 with the stock 7cc dish pistons and would use a .040 gasket, so that would make it like ~ 9.9:1 with 59 CC heads ?(PRC 5.3 stage 2.5) Would it be worth the trouble to mill the heads down to a 55cc-56cc (assume PTV is ok) to make it around 10.5:1 ? Will it make much more power ? Sound better ? (torquer V2 cam) Is there anything else I can do to gain more compression that I've missed?
I used http://www.rbracing-rsr.com/compstaticcalc.html
B 3.78
S 3.66
Gs .040
DH .008
PV +7cc
CC 59 / 56 / 55
I have a 5.3 with the stock 7cc dish pistons and would use a .040 gasket, so that would make it like ~ 9.9:1 with 59 CC heads ?(PRC 5.3 stage 2.5) Would it be worth the trouble to mill the heads down to a 55cc-56cc (assume PTV is ok) to make it around 10.5:1 ? Will it make much more power ? Sound better ? (torquer V2 cam) Is there anything else I can do to gain more compression that I've missed?
I used http://www.rbracing-rsr.com/compstaticcalc.html
B 3.78
S 3.66
Gs .040
DH .008
PV +7cc
CC 59 / 56 / 55
On The Tree
Joined: Jul 2008
Posts: 170
Likes: 0
From: Over the rainbow
Interesting thread 
Im thinking of doing similar with my 346ci with stock 853 heads.
Would it be worth milling the heads by XXX thou and fitting .040" cometics when I drop my baby cam (224ish
), LS6 intake and valve springs in.
Can't wait to hear some opinions so here's the free bump
Im thinking of doing similar with my 346ci with stock 853 heads.
Would it be worth milling the heads by XXX thou and fitting .040" cometics when I drop my baby cam (224ish
), LS6 intake and valve springs in.Can't wait to hear some opinions so here's the free bump
Interesting thread
Im thinking of doing similar with my 346ci with stock 853 heads.
Would it be worth milling the heads by XXX thou and fitting .040" cometics when I drop my baby cam (224ish), LS6 intake and valve springs in.
Can't wait to hear some opinions so here's the free bump
Im thinking of doing similar with my 346ci with stock 853 heads.
Would it be worth milling the heads by XXX thou and fitting .040" cometics when I drop my baby cam (224ish
), LS6 intake and valve springs in.Can't wait to hear some opinions so here's the free bump
me too ...
TECH Junkie
Joined: Dec 2005
Posts: 3,092
Likes: 11
Not being an LS1 man I can see one posible problem with milling to much. That would be the intake manifold would not line up correctly with the heads. On a regular SBC you could just mill the intake manifold to match the heads. I don't think you can do that with the LS1 style intake. So I think you would be limited in how much you can mill or you will get into trouble as you stated.
Sorry for the hijack but I had a 224 on a 112 LSA and it loved 11-1 compression. Put down 400rwhp through a locked auto with TSP 2.5 5.3 heads. But to the OP yes it helps a good bit raising the compression expecially with a bigger cam.
Interesting thread
Im thinking of doing similar with my 346ci with stock 853 heads.
Would it be worth milling the heads by XXX thou and fitting .040" cometics when I drop my baby cam (224ish), LS6 intake and valve springs in.
Can't wait to hear some opinions so here's the free bump
Im thinking of doing similar with my 346ci with stock 853 heads.
Would it be worth milling the heads by XXX thou and fitting .040" cometics when I drop my baby cam (224ish
), LS6 intake and valve springs in.Can't wait to hear some opinions so here's the free bump
with my 59cc AFR 205 heads and a 224 cam... my ratio is right around 11.2:1 and the car absolutely LOVES it... I wouldn't be afraid of it... but I'm sure there's a limit. I'm completely satisfied with it and have NO regrets...
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Staging Lane
Joined: Jul 2008
Posts: 85
Likes: 0
From: Prosperity SC
My setup I have the TSP stage 2.5 5.3l heads milled down to 59cc with a TSP233/239 on a 112LSA. Supposively my compression is about 11.1-11.2 but i am not quite sure. when my engine builder checked the heads he said they were actually 57cc. i dont know for sure and i am not taking them off toget checked it runs great. so far as milling the intake down i DID have to because the guide pins were hitting the outside edge of the line up holes on the heads. TSP said i shouldnt have had to but i DID. ohh well it wasnt that hard i just was a little skeptical about doing this to a brand new intake. so have fun with the higher compression still waiting on getting mine tuned as well. i am also doing the two foot drive. haha good luck
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Compression is a huge helper in making big power. Our dyno testing showed most of the heads we compared that were out of the box were for the most part seperated by the compression differences. We had a small runner 66cc head make 522hp, while our 5.3l 2.5head with 62.5cc make 533hp & our new prototype casting made something like 539hp with 61.5cc chambers.
Milling 6cc of a head made nearly 20hp in our testing.
Milling 6cc of a head made nearly 20hp in our testing.
__________________
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
My 5.3's are milled to a 54 cc chamber. My intake bolted right up too.
I have 4cc mahle flat tops with reliefs and my compression still calculates to 11.73 with a .051 gasket. My stock lq4 would have been 11.63 if I had used these heads on that motor which is in my trans am.
my 347 is useing the 54 cc heads and going in my Nova.
My Trans am now has a lq4 with 241 casting heads milled to 63 cc chambers and my compression is 10.43/1 . This along with an f14 cam feels pretty strong but dont have new dyno numbers. I street tuned it but have not had time to take it to Thunder and see what is left with a little more timing yet.
I have 4cc mahle flat tops with reliefs and my compression still calculates to 11.73 with a .051 gasket. My stock lq4 would have been 11.63 if I had used these heads on that motor which is in my trans am.
my 347 is useing the 54 cc heads and going in my Nova.
My Trans am now has a lq4 with 241 casting heads milled to 63 cc chambers and my compression is 10.43/1 . This along with an f14 cam feels pretty strong but dont have new dyno numbers. I street tuned it but have not had time to take it to Thunder and see what is left with a little more timing yet.
you are showing .008 for deck height, if it sticks outthe block like most ls1's it should be -.008 . that will change it to 10.95 with a 54 cc or 10.81 wtih a 55 cc.
also the stroke is 3.622 not 3.66
also the stroke is 3.622 not 3.66
I converted mm to inch is how I ended up with 3.622.
edit: I'll have to measure it later I forgot the motor is upside down I haven't put the main caps back on yet
Last edited by 1slowcar; Sep 7, 2008 at 08:42 PM.
Interesting thread
Im thinking of doing similar with my 346ci with stock 853 heads.
Would it be worth milling the heads by XXX thou and fitting .040" cometics when I drop my baby cam (224ish), LS6 intake and valve springs in.
Can't wait to hear some opinions so here's the free bump
Im thinking of doing similar with my 346ci with stock 853 heads.
Would it be worth milling the heads by XXX thou and fitting .040" cometics when I drop my baby cam (224ish
), LS6 intake and valve springs in.Can't wait to hear some opinions so here's the free bump
with stock unmilled heads you would see 10.68 with a .040 gasket. if you mill 2 cc's off which is about .012 , you would be at 10.95/1
and if your cam is 112lsa with a 108 cl you would have a dcr or 8.66/1
with that cam on a 110 icl it would be about 8.52 which would be better for pump gas. either way you would make good power.
