after the install of pistons. everything seemed fine. but at WOT im only seeing 7lbs. no codes or anything has came up. has anybody ever had this happen or has it happened to them. will it pass over time or do i need to go get it re-tuned. thanks

 

double check all of your vaccum lines first of all...if no codes are being thrown and the car feels as strong...might have a fugged guage?!

 

it could be a couple things belt slippage, need tune, or some vaccume lines off or not connected

 

the car doesnt feel as strong but i did double check all the hoses. i will go look at the belt later. and get back to you.

 

i am sure with new pistons you are gunna need a tune

 

It could be that since you are running higher compression pistions the Eaton might be having trouble keeping all that air in there. What is 20psi on an 8.5:1 is going to be different on a 10:1 without a check valve. That blower is only going to be able to output so much pressure before you are gonna get cavitation. Anyone else have other thoughts on this?

 

that is possobly so true that is why you run smaller compression on forced inductuioed cars

 

Spray carb cleaner all over your vac lines to see if you can find a leak.
Check your boost bypass valve, make sure its operating right.
check the solenoid make sure i didnt crack or anything.
check your intake manifold's gasket, might be leaking from there.
You SURE all your vac lines are in the right places?
theres something mechanical going on.

 

Not true. Compression happens after the intake valve is closed, so it should have a negligible effect on the boost pressure in the manifold, if anything it will raise it due to more air being pushed back during the first part of the compression stroke while the valve is stilll open.

Check your manifold gaskets, the one against the head and the one under the blower, I bet your leak is happening there. Also look around your endplate, it has to seal air as well. Make sure there is nothing leaking on the lined connected to the boost bypass valve. If none of this works, do the boost bypass mod and see if it changes. If it does, its electronic. If not, you still have a leak somewhere or the belt is slipping.

Also, does the car sound normal at idle? If the idle is off, one of your cams could be off a tooth. That would cause a loss of boost and power, but it would be at least a little noticable all the time.

 

I understand what you are saying however, the timing on a normal car does not close the intake valve completely before the piston starts to move upward. This has to do with the fact that allowing the fuel/air mixture to expand is more important that getting higher compression by closing the intake valve BEFORE the piston starts to move up. So what Im saying is that all your boost happens on the intake stroke obviously, but I think the higher compression may not be allowing the blower to pump enough air in there before its expansion/mixing occurs. This is called cavitation. Its like if you were to run a pump but close off the outlet. Eventually you would be getting reverse shock pulses back into the impellar. This could be happening to your car, meaning the shock pulses could be sending some of that air back into the supercharger. Im surprised you dont need a check valve for this setup as ridiculous as that sounds.....

 

READ MY POST

I covered what you are saying, if you were getting a less than ideal seal of the INTAKE valves, you would see RAISED boost pressure. The air has to go somewhere, either it goes into the engine to burn the fuel, it sits in the manifold and raised manifold pressure, or it escapes into the atmosphere and lowers manifold pressure. Think about it a little bit, which does his problem sound like, if he is only seeing 7psi indicated?

Also, the higher compression pistons change the final size of the combustion chamber at TDC by taking up more space, either by being domed or raised or thicker than stock. For the few degrees past BDC before the valve closes, this slightly larger size/smaller capacity will be next to nothing, we are talking about a small change when the entire column is compressed, from 9.5 to 10.5 or whatever is not very much volume.

Finally, on the caviataion issue: Cavitation would happen at a given pressure where the pump becomes incapable of pushing any more fluid. In this case, if he is getting cavitation at 7 psi, then there is something wrong with his blower as we all know stock blowers are capable of 20 psi or more. Don't guess at what might be happening if you don't know, this is how these strange ideas get started.

I could pick more at your post, but I'm not in the mood right now.

 

ok well it was the boost line from the supercharger it wasnt hooked up right. also we need to change the cam sen. b\c its 180deg. off and its holding revs as i drive down the road. so everything should be right tom. thanks for all the input this build has been hell. first time and everything didnt go as planed. but should be ok.

 

sounds like you shouldnt have gone 10:1. i thought you what want to lower it or keep 9:5:1. other wize you lose boost

 

plus man did you get a tune? you change something like that you need to get it tuned. you might not get it all back but maybe some. i don't know never seen what 10:1 does to boost.

 

i have to wait untill i start beaing on it for the rings to break in. but we did a quick test run and the boost jump to 15lbs by 3-4 rpm and started climbing. then i shut down. so it seems fine. i raised comp. but i put a bigger casket. so i really only raised it like .3 compression. so im prob. at 9.8:1 or something.

 

glad you found the problem, I"m also stuck at 7psi, but that's where the wastgate is set lol.

 

correct me if i'm wrong, but i thought our engines were entirely otto cycle, meaning intake is closed before compression stroke. since we don't have variable valve timing or lift applications, we don't get a chance to become "atkinson-like" at low rpms like the other ecotecs (or hondas w/ vtak) for fuel economy purposes (although if we did have that availability, we would technically be Miller-cycle with the S/C).

 

Please don't confuse the noobs. Just let them argue it out, that way no-one gets hurt. Besides, he fixed the problem.

/thread

 

my bad, i'll dumb it down for every1 in the future...

 

now im throwing the p0069 code. we already looked it up on alldata but the shop closed so we will look into that on monday. im just trying to find out what i can about the code. i did a seach but noone put on how to fix it.

 

ASE certification or not, you were wrong and I was correcting you. Sorry if I hurt your feelings, but you came in trying to correct my statements, which were already right, with incorrect information. I don't like that, because that is why there are so many confused people on here. If they are just your ideas, state it as such, maybe ask someone who knows if your ideas are right before posting them.

Also, the noob comment wasn't specifically directed at anyone, just that bringing up a discussion of Miller/Atkinson/Otto cycles would be WAY above most people on here and would just add unnecessary confusion.

 

I am also ASE certified in four areas, but i still have no idea what yall are talking about...

 

ASE is bullshit. I could pass all those test, doesn't prove anything. I have known some real idiots that still managed to get ASE certified. I can explain it to you, but valve timing is a HUGE topic. Do some research on the firing cycle types we listed, read up on the theory and purpose of both, it will help you a lot if you already understand the basics of how the valvetrain works. ASE shows you know how it works, if you can explain the differences between Atkinson/Otto/Miller and such, then you understand WHY it works, and that is a whole different level.