Is it necessary to do both a leak down and compression test when buying a CTSC NSX?

[Zmoney]

I spoke with Shane at Autowave to inspect a CTSC NSX I was am looking to buy. He assured me that a proper leak down test is enough and if anything looks off, to investigate further. Can anyone else shed some light on this subject?

BTW, Autowave did the install of the CTSC on this NSX

Thanks everyone!

 

[BATMANs]

I would do both to be safe.....

 

[Rusted_nailz]

I believe a leak down test is more thorough than a compression test. It wouldn't hurt to do a compression test though.

 

[Zmoney]

Thanks for the feedback. I guess it can't hurt to do both...just trying to understand that if a leak down is done and checks out, why the need for compression test? Sorry if that's a dumb question.

 

[Larry Bastanza]

Just an FYI, I typically go the other way

Compression test first, if OK, done. If suspect, then I do a leak down to determine exactly what is causing the compression issues.

HTH,
LarryB

 

[Coconut]

I had Shad @ Driving Ambition do a compression test on my CTSC NSX. I asked him if a leak down test was recommended and he said no since the compression numbers were very good.

 

[scbeast]

I got the same answer from SOS in phoenix - leak down test if compression numbers are not good.

 

[jwmelvin]

If the compression numbers were 160psi on all cylinders, would that be good enough or would you be concerned? I know its above the 142psi specification but it seems a bit low. Engine has only 36k miles, all with CTSC.

 

[Big_D]

If the compression numbers were 160psi on all cylinders, would that be good enough or would you be concerned? I know its above the 142psi specification but it seems a bit low. Engine has only 36k miles, all with CTSC.

Do you know if those compression numbers were with a wide open throttle position? That makes a big difference in compression for the test.
Main thing to consider if all cylinders are within +/- 10%. since your is showing the same across all cyls then I probably wouldnt bother with the leak down.

 

[jwmelvin]

It was Nabil at First Class Auto in Orlando, who seems to have a very good reputation around Prime. I just talked to him again and he said that it was at WOT but that it didn't make much difference when he tried it with the throttle closed, contrary to usual behavior.

He said that the pressure jumped to 90 with the first cycle, which in his experience is a very good sign. He thought that perhaps the battery was a bit weak since it was a little sluggish even with just the one cylinder plugged.

He isn't concerned about it and thinks the engine is in good condition but I'm trying to be careful with ground I have never traversed (CTSC).

Thanks.

 

[Honcho]

If the compression numbers were 160psi on all cylinders, would that be good enough or would you be concerned? I know its above the 142psi specification but it seems a bit low. Engine has only 36k miles, all with CTSC.

I would be concerned. A healthy NSX at sea level typically will test around 200 psi. An exceptional engine will test 215+.

 

[jwmelvin]

So what would be the next appropriate step?

 

[Lamchop168]

Ben from Daisy Auto did my PPI at VA and bank 1 and 2 came out 181 PSI. His PPI indicates that this is ALL GOOD given the CTSC blower install was stellar! Ben said that my car is a gem and a steal.

From what Honcho is saying I think he's referring to non SC cars. Any SC cars would have a lower compression PSI. Am I right here or should I be concern of 181 PSI on both banks?

 

[jwmelvin]

Ben wasn't particularly concerned about the 160 number from the car I am considering.

 

[Larry Bastanza]

Do you know if those compression numbers were with a wide open throttle position? That makes a big difference in compression for the test.

This is a key factor, and a very good point. It is also missed alot with 1995+ since they are DBW throttles. The CTSC will also lower air flow to some extent. Again, even #'s are your friend.

Regards,
LarryB

 

[vivanshah]

This is a key factor, and a very good point. It is also missed alot with 1995+ since they are DBW throttles. The CTSC will also lower air flow to some extent. Again, even #'s are your friend.

Regards,
LarryB

how does the DBW throttle affect this? Will the throttle body not respond to the pedal unless the car is actually running?
How does one get around this when compression testing a DBW NSX?

 

[Larry Bastanza]

how does the DBW throttle affect this? Will the throttle body not respond to the pedal unless the car is actually running?
How does one get around this when compression testing a DBW NSX?

I am not 100% certain about the programming, but I have had differences with these DBW models unless I mechanically hold the throttle flap open. Typically a safe bet is a screwdriver handle, since it will hold the throttle plate open, and not get sucked in.

My $.02

Regards,
LarryB