View Full Version : Blown SR :( need advice

10-26-2003, 01:29 AM
Seem I am short on luck lately. I just finished a major upgrade to my car and it back fired on me. I have 1989 240sx coupe with a Redtop motor. I had it running stock for a while and all was great, motor has 69,000 km on it. Had great compression when I bought it. I decided stock wasn't good enough so I started buying bolt ons.

Here is a short list of mods installed in the last month.

HKS downpipe
JIC full SS exhaust
Koyo Radiator
Greddy o2 extension
Upgraded T28/T3 turbo
HKS Type S Front Mount intercooler
Sard 550cc Injectors
Enjuku Racing Remapped ECU
Apexi AVCR
Tein HE's
Defi Boost gauge
Walbro 255HP Fuel Pump.
ACT Street Disc Clutch

After I installed turbo and injectors and ECU and MAF, everything worked great. Car fired up on first try, idled perfectly, I was still running with no boost controller, around 11PSI. I took it around the block and fried the stock clutch on the first second gear pull. That sucked, but I knew stock clutch was gonna fail anytime anyway. Took my car to Garageworks in palmdale to get the clutch replaced. They did a great job and car was back on the road in no time.

I drove it around like that for a 2 weeks, everything was nice, car was quick but I wanted more. So 2 weeks ago, I installed the apexi avcr, install went smooth, I loved all the options of the boost controller. I turned up the boost to 1.1 bar and started driving the car around block. Car was a monster, I could not get traction in first or second gear. I drove it once around block and came home, popped hood and saw OIL all over the firewall.... not good. I started looking around and noticed that it was comming from valve cover. I took it off and inspected the gasket, found it torn at the back. I was relieved, gasket aint a big deal. Ordered a new one next day from Enjuku, got it 2 days later. Installed it, took car for a spin, found no leaks. Car felt funny on the way back though... I was parking it and noticed white smoke from exhaust... I knew I was screwed. I parked it, pulled my compression gage and ran a quick check..

Cylinder 4 155 compression
Cylinder 3 153 compression
Cylinder 2 5 compression
Cylinder 1 155 compression

I had no chance to take it apart yet, but it's obvious I am burning coolant and that the headgasket is toast. What worried me is when I took the plugs out, they didnt look good. I had installed brand new irridium NGK plugs, stock heat range during the upgrade. Plug 4 has about quarter of the electrode melted, Plug 3 had part of the insulator around the electrode missing... Plug 1 looked ok, plug 2 was so so...

So, question is what caused the failure? [censored] stock headgasket? Lean condition? Too hot spark plugs? I will be tearing the motor apart tomorrow, but before I slap a new metal headgasket I wanna make sure everything is ok. I do not have a EGT gaugue or a wideband so I do not know how well the Remapped ECU is running. I do not want to blow the motor next time I hit 18psi and instead of the gasket failing I will get nice melted pistons.

Any advice appreciated.

97 S14
10-26-2003, 02:00 AM
First of all for God's sake put in cooler plugs! NGK 3330's work nicely. Secondly you really need to get an EGT. Third, go get dyno'ed with a wideband just to double check that your within normal A/F.

You probally blew the headgasket because of the spark plugs, be thankful that it blew or else it could have been your piston.

10-26-2003, 04:33 PM
definetly want to hit up a dyno next time, hopefully its only the headgasket. definetly get a thicker metal one, to lower the compression a bit. sounds like you leaned out for whatever reason, you should have enough fuel to back it up, you will need fuel tuning though

10-26-2003, 04:50 PM
definetly get a thicker metal one, to lower the compression a bit.

NO! if problem is still unknown, do not replace the stock headgasket with less-forgiving metal gasket.
the tenth or two-tenth of compression ratio lowered by the thicker than stock gasket is not going to be the solution to this problem.


The Head
10-26-2003, 10:30 PM
judging from the description of the plugs you had some wicked detonation dont be suprised if there is a hole in your piston or chunks missing from your ringlands

10-27-2003, 08:47 AM
when you say "stock" heatrange do you mean 5 or 6?

what octane Gas are you running?

your description of your sparkplugs doesnt sound very promising.

10-27-2003, 03:01 PM
91 octane california gas http://forums.freshalloy.com/images/graemlins/frown.gif They are Denso Iridium IQ20

10-27-2003, 03:34 PM
Um running around on 1.1 bar all the time isn't too good either. Also you really need to tune it when you get a new turbo.

steve shadows
10-27-2003, 03:44 PM
Hi, its me steve the guy who helped you put the turbo and ic on the car. The enjuku tuned ecu could have been the problem, im not sure maybe you should contact ken and see if the ecu is ok for that. I remeber the car ran perfectly and smooth seemed like a very nice map. If anything an air fuel gauge will work as a check and balance. The metal headgakset is an ok idea as long as you make sure the bottom end is fine. If your in doubt you could slap on a stock one for 60 bucks fire it up and see if your compression is back to normal if the tops of the pistons look ok. If everything checks out, get the dp bunged for a wideband o2 sensor bring it up to long beach and ill put your car on the wideband and we can make some pulls in gardena on the dyno and see what your af ratio is as well slowly increase the boost in incriments. Im not too familiar with the enjuku ecu. Ill email ken on it tho. Is there any serial number or anything on it? also did you regap your plugs to .025-.030 approx when you put them in?


10-28-2003, 03:47 PM
I really doubt luck has anything to do with your troubles... it's probably have something to do with lack of knowledge, experience, and patience

10-28-2003, 05:48 PM
Thanks for stating the obvious! I would not be posting if I had all the answers. I don't have as much experience as some of the people on these boards, hence I am asking questions and I have no idea what patience has to do with my problem?

11-08-2003, 04:45 PM
Finally had enough time to take the motor apart. It doesn't look good. Headgasket did not fail. Cylinder 2 has vertical stripes going up and down on the surface. Looks like a ring fried.

So, what would you guys do? Drop oil pan remove the piston, manualy clean up the cylinder wall and reinstall with fresh ring?

Get another shortblock? If one ring died, what are the chances that the rest of them could die if I fix this one?

I dont wanna spend a ton of cash if I dont have to. I will never exceed 320WHP on this motor.

Any advice? =P

11-08-2003, 06:15 PM
As I was reading this, I kept thinking, "he doesn't have a blown head gasket, he's detonating!" Melted spark plugs mean things are way too violent in the combustion chamber. I was going to suggest you do a leakdown test, but it sounds like you've already discoved the damaged ring. I'm guessing you'll need to have the cylinder wall resurfaced, but you should probably get a professional opinion.

"If one ring died, what are the chances that the rest of them could die if I fix this one?"

I would say very good unless you know why you're detonating and have fixed it. Was the ECU tuned for your specific fuel setup and airflow? Do you have a fuel pressure gauge? When was the last time you tested the intake tract for boost leaks? Are you boost creeping? Put an EGT on there at the very least, but logging timing and knock or putting in a wideband and dynoing would be nicer solutions.

Good luck, and sorry to hear about the troubles http://forums.freshalloy.com/images/graemlins/frown.gif

P.S. When you get the car running again, keep the boost down until you can get it tuned properly.

David C.
98 Eclipse GSX