My friend blew the engine in his S4 NA a couple days ago, he's considering re-build, but he wants to know if there anyway to tell how bad it's blown without ripping the whole thing apart. It runs..but barely. Huge knocking noise coming from the back of the engine. It won't hold idle, and won't rev past 3000. Don't ask me why he was trying to rev an obviously blown engine, but people do strange things when their car blows up.

 

No, you would have to tear it down to see if there is any damage to the housings, etc.. You could do a compression test to try and identify what may be the major culprit. Whether it be low compression or a chunked apex seal.

 

Well, your going to have to remove the exhaust manifold anyways to pull the engine..


If you remove the manifold, and take a mirror..you can look inside and check if it has apex seals intact or not. A compression test would do this more effectively, but eh, you can also do this to see if your rotors are junk.

 

My blown engine dynoed 305WHP.

 

LOL! I believe you man, but I just can't understand how a "blown" engine can pull numbers like that on a dyno??? I am baffled

 

Compression test?

 

Sorry to thread hijack, but absolutely no compression on the back rotor: Possible damaged rotor ect? Just wondering if I should buy an engine or get this one rebuilt and I'm trying to weigh costs before I get committed to either one.

 

Just drive it around...Rexryder has at least 1 if not two blown apex seals on the rear rotor and he is still pulling 305whp on the dyno and racing it on the street.

 

Ha, sure buddy, whatever you want to tell yourself. I already pulled the motor and I didn't even have enough power to drive it home 3 km (there was a hill) or even onto the trailer. I just want to know if there might be a lot of damage, with there being no compression at all.

 

Yes, it is very possible that there is damage to the housing. You will not know to what extent until you tear it apart.

 

Thanks for the straight answer. Looks like I have my path set for me then.

 

Pal you need to relax. I was being sarcastic. read the whole thread.

 

roid rage

 

So was I....

 

Damn its so hard to tell on the internet

 

Yea me and my friends were baffled too. It kinda sounded like a V8 with a huge cam at idle, but when I'd rev it, you know it's sounds like a rotary. It idled at 1200 RPM but had 100-200 rpm fluctuation, depended on the outside temps. It was always hard to start, even had to push start it sometimes. The 1st dyno was 270 WHP, then I tweaked my Microtech a little to a final of 305WHP. This was only with 4 pulls on the dyno, and at 85-95 degree temps. So at night I'm pretty damn sure its 340-350WHP. And I run nothing but regular 87 octane gas.

My mods:

Microtech LT-8 tuned by me.
t04e 60 trim @ 18-20 PSI
V-mount intercooler setup
Full 3" RE AMEMIYA DUAL EXHAUST (one of 3 in the U.S. I know of)
OBX turbo manifold
HKS 40mm wastegate.
filter intake on turbo
chevy dual pass radiator
and other stuff I forgot.

Anyway I'm tearing apart the motor pretty soon to find out exactly what happened, and will be making a new thread in this section.