View Poll Results: 10.75:1 or 11.5:1
Voters: 88. You may not vote on this poll
11.5:1 Cr?
Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
11.5:1 Cr? I've a 02 Formula M6 and currently running full bolt-on.
With a stock bottom end, no piston or internal modify and 5.3 ported head, can I achieve 11.5:1 compression ratio?
Also with 11.5:1 CR, stock bottom end and 5.3 ported head, what cam I can/should use to achieve 420+rwhp?
Last question, is it worth it to run 11.5:1? Or should I just get a big-O-cam (MS3-4) with stock CR and call it a day.?
I really wanna see some 450rwhp N/A but 420 will be enough.
With a stock bottom end, no piston or internal modify and 5.3 ported head, can I achieve 11.5:1 compression ratio?
Also with 11.5:1 CR, stock bottom end and 5.3 ported head, what cam I can/should use to achieve 420+rwhp?
Last question, is it worth it to run 11.5:1? Or should I just get a big-O-cam (MS3-4) with stock CR and call it a day.?
I really wanna see some 450rwhp N/A but 420 will be enough.
Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
That actually is my question, what cam I can run without flycutting piston? I'm hoping to run TSP MS3-4, if not 228R. My friend has MS4 with stock head and bolt-on dyno 424rwhp (stock CR).
That's why I've the last question, is it worth running 11.5:1?
Put it this way, which route you guys suggests, Pro and Cons;
1) Run 11.5:1 CR on milled & ported 5.3 head with a small cam (224R or 228R)
2) Run 10.75:1 CR on NON-mill but ported 5.3 head with a big cam (233/239 or MS3)
That's why I've the last question, is it worth running 11.5:1?
Put it this way, which route you guys suggests, Pro and Cons;
1) Run 11.5:1 CR on milled & ported 5.3 head with a small cam (224R or 228R)
2) Run 10.75:1 CR on NON-mill but ported 5.3 head with a big cam (233/239 or MS3)
i had ported 5.3s with a 228r and a fast 90/90 and made 436 rw with an m6. never checked ptv but my heads were milled alittle also so i'm sure it was close. if something like a 232/236 on xer or xfi lobes would clear that would be a good compromise that will still make good torque and put down some great hp numbers also.
More compression = more power everywhere.
It's enough to close the gap in peak power as .75 CR points generally can be viewed with around 3-4% in power gains. At 400rwhp, that's enough for a 228 cam to effectively bridge the 15rwhp its down vs a 238ish cam.
But because the 228 cam already is up in the bottom end and midrange versus the larger cam, the added compression will only help it make a ton more throughout the whole RPM range.
Ideally, with a willingness to flycut, you could go with ported heads that have been milled down, thinner gaskets for better quench, and then run a large cam to make even more topend power and shore up any softness in the bottom of the curve.
It comes down to what your goals are, what sort of drivability you want, and what sort of mods you are willing to invest in. With a more restrictive intake tract and exhaust, the difference in power between a larger cam and smaller cam will be less than what you're expecting.
I voted for more compression and less cam if those remain your options.
It's enough to close the gap in peak power as .75 CR points generally can be viewed with around 3-4% in power gains. At 400rwhp, that's enough for a 228 cam to effectively bridge the 15rwhp its down vs a 238ish cam.
But because the 228 cam already is up in the bottom end and midrange versus the larger cam, the added compression will only help it make a ton more throughout the whole RPM range.
Ideally, with a willingness to flycut, you could go with ported heads that have been milled down, thinner gaskets for better quench, and then run a large cam to make even more topend power and shore up any softness in the bottom of the curve.
It comes down to what your goals are, what sort of drivability you want, and what sort of mods you are willing to invest in. With a more restrictive intake tract and exhaust, the difference in power between a larger cam and smaller cam will be less than what you're expecting.
I voted for more compression and less cam if those remain your options.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
I voted 5.3's with 224. My current build consists of an LS6 with stage 1.5 TEA heads with ferrea 2.02 intake valves and stock exhaust valves. With the heads milled to 60cc and using a .040 cometic gasket (.033 quench), My compression is right at 11.5:1 with a torquer v2 cam on a 112lsa +2. And my PTV clearence was .000 on the intake side, I ended up flycutting the intake side .130 and the exhaust side .080 to make it fit. I'm capping it off with a ported fast 90 LS2 ported 90 combo and TPIS 1-3/4" headers and shooting for 475+ at the wheels and flat torque curve.
Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
One side question (kinda stupid), did I have to tear down the engine to have the piston flycut?
Basically 11.5:1 is my ideal setup. Cuz it's part of my DD and I barely go to 1/4 race. The thing I most do is hillside twist. If necessary, I'll be willing to lower the CR to 11:1 with a little bigger cam. Or I should go for a custom cam grind to keep 11.5:1 CR?
PS: with 11.5:1, 5.3L ported head and 224R, full bolt-on, what kinda HP level I should expect?
Basically 11.5:1 is my ideal setup. Cuz it's part of my DD and I barely go to 1/4 race. The thing I most do is hillside twist. If necessary, I'll be willing to lower the CR to 11:1 with a little bigger cam. Or I should go for a custom cam grind to keep 11.5:1 CR?
PS: with 11.5:1, 5.3L ported head and 224R, full bolt-on, what kinda HP level I should expect?
Last edited by darknessxyz; Oct 10, 2008 at 12:58 PM.
One side question (kinda stupid), did I have to tear down the engine to have the piston flycut?
Basically 11.5:1 is my ideal setup. Cuz it's part of my DD and I barely go to 1/4 race. The thing I most do is hillside twist. If necessary, I'll be willing to lower the CR to 11:1 with a little bigger cam. Or I should go for a custom cam grind to keep 11.5:1 CR?
Basically 11.5:1 is my ideal setup. Cuz it's part of my DD and I barely go to 1/4 race. The thing I most do is hillside twist. If necessary, I'll be willing to lower the CR to 11:1 with a little bigger cam. Or I should go for a custom cam grind to keep 11.5:1 CR?
A good off-the-shelf grind would be the Torquer 2 (Comp XE-R 232/234 113+0). It'd be ragged edge close ~ .060" P-t-V clearance with .040" gaskets and 59cc chambers and 2.00" intake valve, so you'd have to measure. But, the stats would be 11.8:1 SCR, 8.7:1 DCR, and a late intake valve closing of 49 (perfect for a 7k RPM 346 with a FAST Manifold). It'd make for a real top end screamer that has power throughout the range due to the early intake valve opening and high dynamic compression. Plus, it has relatively mild overlap, so it'd idle and behave pretty good on the street.
I have a big cam with milled heads...
LG G5X3 112lsa and AFR 205 heads that are milled to 59cc, using stock style MLS gasket: People say my compression should be somewhere around 11.5:1
I made 433/410 through the stalled auto
As for clearance wise I barely make it, never checked but I just went from what people told me and thank god it has held on, without any fly cutting. Before this setup I ran the AFR's with the TSP 224R and a stock transmission made- 410rwhp with a hurt exhaust setup. With your car being a M6 I'm sure you could be right at your goal of 420 with properly milled 5.3 heads and either of the two cams.
Hope a little bit of personal experience helps...
LG G5X3 112lsa and AFR 205 heads that are milled to 59cc, using stock style MLS gasket: People say my compression should be somewhere around 11.5:1
I made 433/410 through the stalled auto
As for clearance wise I barely make it, never checked but I just went from what people told me and thank god it has held on, without any fly cutting. Before this setup I ran the AFR's with the TSP 224R and a stock transmission made- 410rwhp with a hurt exhaust setup. With your car being a M6 I'm sure you could be right at your goal of 420 with properly milled 5.3 heads and either of the two cams.
Hope a little bit of personal experience helps...
11 Second Club
Joined: Jun 2005
Posts: 1,537
Likes: 0
From: Was New Orleans, but swam to Baton Rouge
I use to run Dart 205s milled to 58 ccs with my F14 cam (232/234). That setup was great. I still compare everything I do to that setup. I think a low 230 cam with the increased compression is a great setup for the track and the street.
Look more into what your'e dcr is than what the staitic cr ends up being.
Pick the cam that give's you the best dcr. Or do the right thing and flycut and run the cam you want to run and bump the cr up.
I am at 11.82 scr with a 238/242 xer combo and love it.
Pick the cam that give's you the best dcr. Or do the right thing and flycut and run the cam you want to run and bump the cr up.
I am at 11.82 scr with a 238/242 xer combo and love it.
Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
yea, that means flyoutting the piston is out of consideration......
Guess I'll stick with either 11.5:1 and 224R or 11:1 and 228R. Which one will you guys choose?
Guess I'll stick with either 11.5:1 and 224R or 11:1 and 228R. Which one will you guys choose?
I have no idea what heads you are running, but if they have the stock valves, you can run a bigger cam and more compression without flycutting.
If you have 2.02 valves, you'll be limited to something closer to a 226 or 228 without as much milling or running as thin of a gasket... but you can still run with more compression than 11.1. And the larger in cam you go, the more you need compression (with all else being equal).
Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
You can go with a 232 duration cam and 11.8:1... as I described above.
I have no idea what heads you are running, but if they have the stock valves, you can run a bigger cam and more compression without flycutting.
If you have 2.02 valves, you'll be limited to something closer to a 226 or 228 without as much milling or running as thin of a gasket... but you can still run with more compression than 11.1. And the larger in cam you go, the more you need compression (with all else being equal).
I have no idea what heads you are running, but if they have the stock valves, you can run a bigger cam and more compression without flycutting.
If you have 2.02 valves, you'll be limited to something closer to a 226 or 228 without as much milling or running as thin of a gasket... but you can still run with more compression than 11.1. And the larger in cam you go, the more you need compression (with all else being equal).