Sr20det 50trim low compression but car runs perfect, HELP please

[BOOSTALOT]

Here i go with my story please try and understand my case

well i recently went big turbo on my sr20det
motor was bone stock (ran perfect) so i pulled the head and had it resurfaced, added a cometic 1.01mm thick, ARP headstuds, and Isis rocker arm stoppers to reinforce the motor. got it street tuned with a power fc and i set the boost at 15psi and the car ran like a champ. (Ran it like this for about 2 weeks)
before i got to take it to the dyno to get professionaly tuned i started noticing some smoke on my passenger seat whenever i would get on it and it honestly smelled like oil. i went ahead and pulled over immediately and checked under the hood, my shitty ebay catch can was dripping oil and my dip stick had blown out of its place. i fgured i had too much compression and was spewing oil on my turbo causing the white smoke. i went ahead and changed my catch can to a bigger unit with bigger entries..it's routed from the front of the pcv<catch can<atmosphere

Once I got it changed I took it for a nice run and noticed the smoke inside the car. I took it to my local shop and popped the hood and found the catch can had filled up..I thought to myself that maybe I had put to much oil in the car and was causing blow by..anywho I drained it and got back on the road to see anything would change, did a couple pulls then pulled over to see That the catch can had once again filled up! (1 quart catch can)
I start flipping shit and take it to the shop that did all the work on the car and the check compression and it shows
110,150,150,150.. These guys now tell me that my piston rings might be bad so I flip shit at these guys and tell them why they didn't mention to me before i went big turbo that should i should have changed the rings when the motor was apart...
The reason why I did t think about the oil rings or anything was because they told me that this motor is bulletproof and with 75,xxx miles there is no need for anything, just the headgasket and arp head studs (I come from a srt4 so am a noob to this motor and as to how much power the stock motor can handle, this is the reason why I took it to a shop)
Now I'm here with a perfectly running car (no smoke at startup, idles perfect, pulls great, lowered to 7 psi)
And a brain filled with ideas of what could cause this..I'm scared to drive the car because I don't to cause any damage!

Maybe I'm ignorant and don't want to face the matter that I may have to pull the motor and get it rebuilt, so before I have to do that I would like to see if maybe by any chance it could be something else causing this low compression on cylinder 1...(pcv valve, too much oil in motor, valve stuck open?? Etc..)
Where should I start?? What to do?

ANY AND ALL THOUGHTS ARE WELCOME!
Please help!!!

Thank you in advance!

[801nismo104]

do a compression test yourself but add a lil bit of oil to the cylinder that has low compression. if it goes up the rings are bad. you can also do a cylinder leakdown test which would be more usefull imo. Theres a great write up on here in the FAQs section look it up

[OrangeVirus1]

freaking piston rings man.

you flipped shit why they didn't tell you before?

what a genius. you ALWAYS compression check an engine you don't personally know about.

sorry for your loss but I mean cmon... Compression check is like the universal law of good engine bad engine.. lol

[BOOSTALOT]

Ill do a leak down test as soon as I have the chance..can I purchase the tools at any autozone or napa right?
I know I should have done a compression test before going turbo but I guess I got ahead of myself and didn't even think about it..but the main reason why I got mad at them is because they didn't warn me or ask me anything..I took it to a professional to get the pros and cons of such and upgrade but I guess I f#(&d up

I'm just trying to figure out if maybe by using sea foam I can clean up any carbon build up which my be causing one of my valves to not seal properly

[801nismo104]

i think you might be able to rent one from autozone for free. sears sell them though. good luck man i hope you get your problem solved

[BOOSTALOT]

Originally Posted by 801nismo104

i think you might be able to rent one from autozone for free. sears sell them though. good luck man i hope you get your problem solved

Thanks for the help man

[4x4le]

Boost dont kill rings, detenation does.

Looks to me like you had too much fun on your "street tune" and should have waited on the dyno tune.

No engine is bullet proof to the point that it can survive detenation.

[BOOSTALOT]

Originally Posted by 4x4le

Boost dont kill rings, detenation does.

Looks to me like you had too much fun on your "street tune" and should have waited on the dyno tune.

No engine is bullet proof to the point that it can survive detenation.

You could be right but then again the a/f ratio was good..I did get on it quite a bit but it just shocks me to see this happen from one day to another...
Could it be a bad headgasket?

[fliprayzin240sx]

Good A/F Ratio dont mean diddly squat if you have too much timing and your engine is pinging. So with the bigger turbo, what size injectors do you have and do you know what fuel pump is in the car? Either way, its too late with the 110 compression. Drop a cap ful of oil in there, if the compression jumps up to 150, bubye rings #1.

[BOOSTALOT]

Originally Posted by fliprayzin240sx

Good A/F Ratio dont mean diddly squat if you have too much timing and your engine is pinging. So with the bigger turbo, what size injectors do you have and do you know what fuel pump is in the car? Either way, its too late with the 110 compression. Drop a cap ful of oil in there, if the compression jumps up to 150, bubye rings #1.

550cc injectors and walbro 255
I'm going to get it do a leak down test this weekend so ill be sure..I'm already accepting that I might have to pull the motor out of the car

[fliprayzin240sx]

If you made over 300whp on that setup, you were probably maxing out those injectors too.

[BOOSTALOT]

My target was 350hp and 550cc was ideal for my goals..there were multiple cars at that shop that are running the same setup as me and they have have seen constant track abuse and dynoed well over 340

[BOOSTALOT]

Bringing my old thread back from the dead here. Just for anyone who does ever encounter these symptoms, it ended up being a cracked piston..timing was wayyyy too advanced and tune was very lean. So it was without a doubt detenation, I have a fully built bottom end now and the car is doing great..

So lesson learned, get your stuff dyno tuned and don't cheap out when it comes to engine tuning!!

If anyone is interested and has 20minutes watch my build on YouTube!
Title of the video:
UPDATE!! 1997 nissan s14 kouki sr20det build (part2) with dyno video!

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[Kingtal0n]

I made 390 with that setup on 740's with HKS and BC cams (tried both) want the graph? Actually I have a video too.

[BOOSTALOT]

I'm about to build my head so yeah, how did you like the bc cams for daily driving?

[Kingtal0n]

The BC 264's sounded like stock. Idle like stock.

here is a graph comparing a 60-1 with a 50 trim (same exhaust wheel/housing) I just swapped out the compressor wheel / housing to do these tests.... and the camshafts (HKS 27X On the 60-1)



and the video on the 60-1 run

[BOOSTALOT]

hmm at 15psi you made the exact same power I'm currently making..what do yu have done to your motor if you don't mind me asking?

still debating what kinda cams i want..maybe 272 idk
and i know my current emusa (ebay turbo) turbo is pretty much maxed out after 16-17psi

[Kingtal0n]

A stock engine with only BC264 (or JWT S3) cams makes that power, All stock sr20det will do it with the right tune (simply 11.8:1 air fuel, and 10-13* of timing btdc on most engines with 93 octane is fine) The OEM head is more than capable of supporting 400~ with just the camshaft upgrades, and S3 are the better choice since they allow you to keep the OEM valve springs, which is the best possible way to run a daily driver.

I would stay with 264 or less duration. Extra is not needed, will increase lag, hurt fuel economy, make it less fun to drive.