Need opinions
10-16-2010, 05:49 AM
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Need opinions I'm have issues again with my vette.I think my compression is too low. After motor was installed the compression was too high ( built to stock LS7 compression). the installer felt it was too high so lowered boost and used a .120 head gasket.It runs rough ect. Here is what that guy that tuned the car told me.
"Typically you wouldn't have any drive ability issues with and cam that size. There is something about you setup that makes it not want to burn good with a lean mixture. I can only guess that it has to do with the head gasket / quench situation as I see they same problem on late 90's low compression big blocks in the trucks.
You can should want to drive down the road at 14.7:1 afr (stoich). At that afr you car wants to surge and not run lean, especially with a little more than flat ground load. When your at 13.5 afr your car happies up and runs smooth. The problem is as soon as your car goes into closed loop and utilizes the stock o2's, the afr automatically goes back to 14.7.
Since the car does ok at 14.7 under some conditions I left the o2's on. To combat the load induced breakup and fight the throttle tip pop I set the tps value very low to let the car go into power enrich mode early and give it extra fuel.
I have a plan but I don't know how good it is. Right now I'm just going to leave it alone, because of winter coming.Plus I do not drive it much.
1. First change out the head gaskets to some thinner ones. Maybe .08 or .09 to get some quench back. I think that the motor is running like 9.2 - 9.4 compression right now. That would be .04 -.030 decrease. I read somewhere stock were .051-.053. Do you think this would be ok?
2. I know why the motor was valve floating, because the springs only go to .650 lift. I called Texas Speed and performance to conform this. The cam is bigger because of the LS7 1.8 rocker arms. I figured out to be somewhere in the .660 range.While I have heads off change valve springs to Precision Race Component .700" Lift Spring Kit.I don't like the cam that is in it so change it also to one of these cams
215/247 .629/.656 121 CL With 1.7 rockers
224/248 117 .625 - LS7 With 1.8 rockers
232/256 114 .660 - LS7 With 1.8 rockers
Which one looks the best? I like the first one.
3.Keep boost the same.
4. LSx ported fast intake
Then after all this have it re tune. Are the intakes worth it? Do you think its a good plan or not?
"Typically you wouldn't have any drive ability issues with and cam that size. There is something about you setup that makes it not want to burn good with a lean mixture. I can only guess that it has to do with the head gasket / quench situation as I see they same problem on late 90's low compression big blocks in the trucks.
You can should want to drive down the road at 14.7:1 afr (stoich). At that afr you car wants to surge and not run lean, especially with a little more than flat ground load. When your at 13.5 afr your car happies up and runs smooth. The problem is as soon as your car goes into closed loop and utilizes the stock o2's, the afr automatically goes back to 14.7.
Since the car does ok at 14.7 under some conditions I left the o2's on. To combat the load induced breakup and fight the throttle tip pop I set the tps value very low to let the car go into power enrich mode early and give it extra fuel.
I have a plan but I don't know how good it is. Right now I'm just going to leave it alone, because of winter coming.Plus I do not drive it much.
1. First change out the head gaskets to some thinner ones. Maybe .08 or .09 to get some quench back. I think that the motor is running like 9.2 - 9.4 compression right now. That would be .04 -.030 decrease. I read somewhere stock were .051-.053. Do you think this would be ok?
2. I know why the motor was valve floating, because the springs only go to .650 lift. I called Texas Speed and performance to conform this. The cam is bigger because of the LS7 1.8 rocker arms. I figured out to be somewhere in the .660 range.While I have heads off change valve springs to Precision Race Component .700" Lift Spring Kit.I don't like the cam that is in it so change it also to one of these cams
215/247 .629/.656 121 CL With 1.7 rockers
224/248 117 .625 - LS7 With 1.8 rockers
232/256 114 .660 - LS7 With 1.8 rockers
Which one looks the best? I like the first one.
3.Keep boost the same.
4. LSx ported fast intake
Then after all this have it re tune. Are the intakes worth it? Do you think its a good plan or not?
