lost hp

redzone · Post by **redzone** » Thu Apr 09, 2009 7:06 am

130ish is fine for a VR4 motor. its not so much about the level though as much as if they are even. the actual psi reading doesnt mean shit really, you just dont want a dud cylinder...

dirtygalant · Post by **dirtygalant** » Thu Apr 09, 2009 7:29 am

130 is LOW! it's definitely down on compression from stock.

Both my VR-4 and Eterna engines had 155psi and they are 7.8:1 and 7.6:1 respectively.

RiceThief · Post by **RiceThief** » Thu Apr 09, 2009 10:14 am

Different compression testers read differently and how the engine is tested affects the results.

dirtygalant · Post by **dirtygalant** » Thu Apr 09, 2009 10:32 am

How so? If your compression tester doesn't read the same as the next one then it's either faulty or the other is faulty. How many ways are there to do a compression test? You screw the tester in, open throttle wide and crank over for as long as it takes (usually 8-10 cranks) to get a stable figure on the cylinder you are testing. How many other ways are there to do a compression test??

RiceThief · Post by **RiceThief** » Thu Apr 09, 2009 11:18 am

i have two tester at home and they read different about 5 psi. Some people do the test with the throttle closed, which will affect the figure, if the plugs are in opposed to being all out affects the figure. As i said put abit of engine oil in before the test that will give you an indication whether the rings are sealing well or not.

dirtygalant · Post by **dirtygalant** » Thu Apr 09, 2009 11:23 am

why would you do it with the throttle closed? whole point of the exercise is to see how much the cylinder can compress air and it's not going to get a great deal of air flowing through with the throttle shut.

Plugs in on the other cylinders is only going to slow the rpm down but you're going to end up with the same figure if you crank it over long enough.

Honestly why do a test with plugs in and throttle closed? it's just a half-assed way of doing the correct test and it's not going to give you accurate results, which at the end of the day is what you want..

It's like going to the dyno with your handbrake half on or your air con switched on.

redzone · Post by **redzone** » Thu Apr 09, 2009 4:02 pm

the type of tester has a bearing on it, the push in ones usually read lower. seriously dude you can buy 2 brand new testers and they'll read 10 psi different. same as boost guages, pretty hard to find 2 that read exactly the same.

dirtygalant · Post by **dirtygalant** » Thu Apr 09, 2009 4:44 pm

I do understand that mate however you can't excuse a 130psi reading because of the tester, the engine is low on compression - plain and simple!

redzone · Post by **redzone** » Thu Apr 09, 2009 8:20 pm

do you realise how RARE it is for an engine to lose compression that evenly across the board? i've been a mechanic for 14 years and i've NEVER seen one do that. always have one or 2 lower than the others.

then there are engines like the sohc with 2.4 head in the orange car, that has 100psi comp across the board, when the engine was just run in, and still same now. starts and runs fine too.. not to mention hits full boost at 3000rpm!

srsly i dont think compression is this engines problem, i just think the tuner ran out of time as he said, and didnt spend very long on the ignition mapping, which is where the power is made.

coop1er · Post by **coop1er** » Thu Apr 09, 2009 8:20 pm

I wouldn't be overly concerned about the compression readings @ 130psi. If the engine runs well and isn't breathing too much then I would be looking elsewhere for a cause of low power. Things like the state of charge of the battery have a big effect on the final result of a compression test.

As far as the power difference is concerned, the tune can have a lot to do with it. The difference between an engine tuned right to the edge of reliability and a safe but still good tune could be 10% to 20% difference in power.

redzone · Post by **redzone** » Thu Apr 09, 2009 8:22 pm

MR Bender wrote:manifold is locked open
The inj are yellow so arnt they evo 1s
The turbo is a small 16g
The tuner said thats all it would make but hey was really busy and didnt want 2 work on it anymore
I stoped the boost there cause i didnt want 2 run as much as b4
The tuner said the fuel pump was really good but it is only a vl pump

in other words, THERE'S the problem.

MR Bender · Post by **MR Bender** » Thu Apr 09, 2009 8:40 pm

redzone wrote:
MR Bender wrote:manifold is locked open
The inj are yellow so arnt they evo 1s
The turbo is a small 16g
The tuner said thats all it would make but hey was really busy and didnt want 2 work on it anymore
I stoped the boost there cause i didnt want 2 run as much as b4
The tuner said the fuel pump was really good but it is only a vl pump

in other words, THERE'S the problem.

yer the tunner had a meeting to go too!
it was a saturday after noon about 4.30pm when it got done so yes he rushed it !
his word where= thats all it will make iv got another place to be im not working on it anymore today!

so i dont know!!! you know its like going into a workshop at 5pm on a friday and asking bullshit questions!!!
but im no tunner so i have to take his word that it was tunned!

NachoMan · Post by **NachoMan** » Thu Apr 09, 2009 8:52 pm

Go back and get it done properly.

Website · Post by **WidebodyWoody** » Fri Apr 10, 2009 12:15 pm

yeah he claims that is all it will make? How long did he spend tuning it? If its any less then 3-4 hours, he didn't do anywhere near a good enough job. A full tune from start takes anywhere from 6 hours plus to get real good benefits. Shorter if it already had a decent base map. Tuning is everything. You can have all the right mods, but without a decent tune, you could make less then stock power.

MR Bender · Post by **MR Bender** » Fri Apr 10, 2009 12:27 pm

WidebodyWoody wrote:yeah he claims that is all it will make? How long did he spend tuning it? If its any less then 3-4 hours, he didn't do anywhere near a good enough job. A full tune from start takes anywhere from 6 hours plus to get real good benefits. Shorter if it already had a decent base map. Tuning is everything. You can have all the right mods, but without a decent tune, you could make less then stock power.

it had a shitty tune in it to start with
but he did only spend about a 1hour and a half on it !

but he did say thats all it would make!!

the problem is that i cant take it back cause the dyno is getting moved and wont be ready for about 4 weeks!
f*$% this pisses me off !!!
i will have to find another tuner but dont want to spend all that money on the car if something is wrong!

Austarion

lost hp

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