twin turbo compression test opinion

[KoBra_98]

I'm looking at buying a tt termi. rebuild has 11k miles on it 9.0 cr.
looking for opinions on these compression test numbers, car has cams also, and wonder what acceptable idle vacuum should be. Here are the test results
1 155
2 150
3 145
4 150
5 145
6 145
7 135
8 140
thanks guys for your help and opinions

 

[itSSlow98]

Looks low to me but it could be a gauge variation. Did you throw a little oil in the cylinders to see if it raised the compression number?

 

[KoBra_98]

its out of state and the owner had a mechanic do a compression test today on it for me. these are the numbers and i wasn't sure what good numbers should be. I'm going to call the mechanic tomorrow after work and see. thanks for the reply! I was also thinking they looked a little low, but i'm not sure what good numbers are for a 9.1 twin turbo car.

 

[xXAzureMach1Xx]

From what i know, As long as the numbers are within a % of each other then they are fine. Think its 10% :shrug:. Over all the numbers dont look bad. The only one i would be worried about is the 135 but thats not to low. My stock motor is 10:1 and i think my numbers were in the 170 range :shrug:

 

[itSSlow98]

A leakdown test is more informative then a compression test IMO. Ive always seen 160-180 for compression tests as the good range.

 

[KoBra_98]

that's what i thought too, i asked for a leakdown test but the owner said the mechanic said it was a PITA to get done. maybe i should insist on it? what do you all think? if the engine is good ill buy the car , but i don,t want to have to put a bunch of cash into it , i want one already done and i can drive ;-) thanks for the replies

 

[itSSlow98]

Insist on the leak down its easier then a compression check. Take my word for it, I'm paying big money right now for taking someone's word that the motor was built right. 2k miles later I'm building a bottom end and only able to reuse the crank thanks to a bad assembly job. They used good parts but obviously didnt know what they were doing. 5k later ill have a good motor finally.

 

[coposrv]

Find out more about the cams. Lobe centerline and duration will affect a compression test.

 

[KoBra_98]

thanks for the info, it appears that a leakdown test is a must , i like the car but i NEED to know the engine is good. please anyone else have anything to add? I appreciate all your replies p.s. the cams are stage 2s not sure on the lift and duration

 

[Juiced46]

Stage 2s doesnt help us. The way the cams are setup will directly affect compression. Like mentioned lober centerline and duration will make all the difference.

 

[KoBra_98]

The seller is doing a leak down test for me. they only got 1 bank done today and got numbers back from 11%-14%. how does that sound to you guys? I read that 20% is acceptable max for a normal car and 10% is the max for a race engine. any thoughts?

 

[Juiced46]

The seller is doing a leak down test for me. they only got 1 bank done today and got numbers back from 11%-14%. how does that sound to you guys? I read that 20% is acceptable max for a normal car and 10% is the max for a race engine. any thoughts?

IMO that is to high.

Usually 5% is my max for an engine like. 14% is high.

I would keep shopping around.

 

[KoBra_98]

Thanks, ill keep shopping. appreciate all your help. ill find a nice low mile TT car. they are out there, especially when you have cash in hand to spend

 

[itSSlow98]

Don't get stuck with a tt car. After seeing the kit installed what a pain in the ass those twin kits are.

 

[KoBra_98]

Yeah i want a car already done, last year there was a TT mystic id have loved to bought, but the seller wouldn't ever get a test done for me to show me things were good. thanks