Max Compression on a 5.3 Gen IV engine? ( Patriot heads preferred )
09-17-2006, 09:55 AM
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Max Compression on a 5.3 (DOD+E85) Gen IV engine? ( Patriot heads preferred ) What i have in Mind is a 310 Hp LC9 ( this is a LH6 DOD with E85 support ) Engine that will mostly run on E85. And ( poor if it has to ) on Premium when i go on a weekendtrip to Austria ( 80 Mph Speedlimit and busy Cops )
I'm not aiming for maximum Performance. I'll be happy with 350Hp - 420Hp on the Crank. Intake, Heads and small Cam ( Comp Cams Xtreme RPM 206/212 .551/.522 112 ) only. Sees anyone a problem with this and DOD/AFM ?
Another Sidenote: Its for an engineswap into a 3rd Gen Firebird.
I'm not aiming for maximum Performance. I'll be happy with 350Hp - 420Hp on the Crank. Intake, Heads and small Cam ( Comp Cams Xtreme RPM 206/212 .551/.522 112 ) only. Sees anyone a problem with this and DOD/AFM ?
Another Sidenote: Its for an engineswap into a 3rd Gen Firebird.
Last edited by Gm-LSX; 09-18-2006 at 12:36 PM. Reason: Adding info to the title
09-17-2006, 10:36 AM
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i'm making 340hp/340tq at the wheels just to give you an idea on what these motors are capable of.
i don't know how different your 5.3 is from mine though.
it's cam only w/ bolt-on's. stock heads, intake, throttle body.
i don't know how different your 5.3 is from mine though.
it's cam only w/ bolt-on's. stock heads, intake, throttle body.
09-17-2006, 03:53 PM
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Sorry if my point got lost. I'd like to increase Compression to the max (in a save and cheap way, so not all to thin gaskets and good VPC) for the 108(?) Octane fuel. And enjoying the benefit of more fueleconomy AND torque/power.
9,95:1 is the Base for this engine.
I think 12-12,5 will be good. Wada you think? What do the PCM guys think about getting Premium to run with this when E85 is N/A? But from what i saw stock chamber sizes will get me only around 11:1
Patriot does cutom camber sizes at no (extra) charge. right?
9,95:1 is the Base for this engine.
I think 12-12,5 will be good. Wada you think? What do the PCM guys think about getting Premium to run with this when E85 is N/A? But from what i saw stock chamber sizes will get me only around 11:1
Patriot does cutom camber sizes at no (extra) charge. right?
09-17-2006, 11:51 PM
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That cam and DOD may not work (unless that cam is specificly designed as a DOD cam).
DOD has specific lobes for 4 of the cylinders, those lobes are different due to the lifters used for those 4 cylinders (I never get this explination out correctly).
This link explains the DOD cam a little better. http://www.greencar.com/index.cfm?content=features46
Basicly you will need a custom grind cam if you plan on keeping DOD.
Or you can drop DOD (replace the lifters and plug the DOD oil lines & remove the solenoids) and go with a LS1 based cam like the one you have listed.
If you're going to push the compression up to 12:1 or better then you will definitely need fuel additive (octain boost) when you are not running E85
I'ld say go with 11.75:1 and tune the computer for Premium fuel + additive when not in E85 mode. But I'm conservative like that.
Speaking of DOD, has any cam company come out with a performance DOD cam?
DOD has specific lobes for 4 of the cylinders, those lobes are different due to the lifters used for those 4 cylinders (I never get this explination out correctly).
This link explains the DOD cam a little better. http://www.greencar.com/index.cfm?content=features46
Basicly you will need a custom grind cam if you plan on keeping DOD.
Or you can drop DOD (replace the lifters and plug the DOD oil lines & remove the solenoids) and go with a LS1 based cam like the one you have listed.
If you're going to push the compression up to 12:1 or better then you will definitely need fuel additive (octain boost) when you are not running E85
I'ld say go with 11.75:1 and tune the computer for Premium fuel + additive when not in E85 mode. But I'm conservative like that.
Speaking of DOD, has any cam company come out with a performance DOD cam?
Last edited by Bring the Noise; 09-18-2006 at 12:12 AM.
09-18-2006, 06:53 AM
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Go here and scroll about halfway down the page. There is a bunch of info on the DoD system. I can't remember if it is listed in there but the DoD lifters can accept up to a .590 lift. (in theory)
The stock DoD cam is dual pattern. The DoD valves get a .492 lift and the normal working valves get a .482. Why GM did that no one really knows. None of us have come up with a good reason. My guess is something to do with the different intake velocity while running in 4 cylinder mode... maybe to produce more torque... i dunno.
Just my personal opinion but if you drive alot of city and over 70 mph then DoD is barely worth it. It works good at 60 mph or so. I think just some good tuning etc could see equal mileage gains.
The stock DoD cam is dual pattern. The DoD valves get a .492 lift and the normal working valves get a .482. Why GM did that no one really knows. None of us have come up with a good reason. My guess is something to do with the different intake velocity while running in 4 cylinder mode... maybe to produce more torque... i dunno.
Just my personal opinion but if you drive alot of city and over 70 mph then DoD is barely worth it. It works good at 60 mph or so. I think just some good tuning etc could see equal mileage gains.
