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Old 05-11-2019, 06:29 PM   #1
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Resurrecting my S13 Redtop SR20DET

Hi everyone,

I've been out of the loop and need some advice as to what direction I should head with my project.
There's no way to make this short, but i'll do my best.

Specsvalid to question)
SR20DET redtop
Stock turbo
Front Mount
3" Turbo back exhaust
walboro 255
wideband o2

I've had this setup running and driveable several times over the last 10 years with a few hiccups...

(10 years ago)
When I did the original swap the SR came with a "Mystery" Blitz tuned ECU and a damaged fuel rail.
At the time side feed setups seemed much pricier, and a friend gave me some free 550cc top feed injector's that had just been serviced, and a S-AFC 2. This friend was running high 11's in a AFC tuned DSM so I figured it would work too.

The car started, idled, and ran ok, but no matter how much we adjusted the S-AFC it always ran extremely rich. It seemed as if whenever we had it dialed in the stock ecu would come along and correct again.

(5 years ago)
Up to this point I was the only person to have ever worked on the car, but someone told me take it to this shop they knew so I did, and regret it. I got the car back missing all kinds of bolts and clips in the engine bay on parts they had been diagnosing. I replaced all the parts, and took a break from it.

(3 years ago)
I drove the car 2-3 times a month minus winter for most of this setup at stock boost but driving it to avoid boosting. While driving it one day it sounded like I popped a Intercooler pipe. Pulled over to check it and couldn't find any loose coupler's or leaks, and it would not start back up. I decided to have it towed. I compression tested it, and boost leak tested it everything was fine. At that time I wasn't in a great position financially and with so many variable's I decided to garage the car long-term.

With my financial situation in a little better place i'm finally considering doing some work. I have a budget of around $3000 right now.
After some recent diagnosing I suspect it could be a bad turbo because I noticed oil/carbon inside the hotpipe from turbo to the intercooler. the turbo spins by hand but not smooth and it does have some wiggle.

I'm considering finally going with a Stand alone EMS Probably Mega Squirt 2 PNP, and maybe a replacement turbo or bolt on upgrade.

The car stills needs lots of other work (suspension, body work, Lsd, better brakes, and tires) I'm not looking to make crazy horse power right now. I just want it to drive like it should.

My main questions would be:
Should I do the EMS first in case its not the turbo?
Is there any way to know for sure the turbo is bad?
Was my issue with the 550cc injectors a Impedance thing?
Is there anything i'm not considering?

Any help would be much appreciated.
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Old 05-12-2019, 05:09 PM   #2
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compression test, boost leak test, timing test,
Get compression numbers from the engine. Use a Decimal place, i.e. 125.4psi, 123.8psi, etc...
IF the engine is below the FSM limit (128psi?) it needs a rebuild. If you get like 135-145psi of compression, and the engine is internally clean and never made any knocking noises etc...
Then I would still trust it at 350hp for a while at least, as long as its always been run with an air filter.
The air filter and PCV system are what keeps an engine clean inside, and healthy for a long time. So if it has those things...

Then put all stock equipment back on. Factory ecu/harness/injectors etc...
Would be ideal. The issue is you don't have a good turbo (no oem sr20 turbo is very 'good' these days) so If you upgrade the turbo, use a brand new unit, and use
power FC + 740cc injector + Z32 maf
if the engine is good and has low mileage.

Otherwise sr20 is double trouble, you got a poor quality engine and poor quality turbo, thats tough luck. Need to rebuild the engine and buy a new turbo.
And if its been run long without a filter, you may need a whole new block.

dont use OEM turbos anymore
dont use USED turbos
dont trust any machine shops to do any machine work
if you attempt a rebuild use the FSM procedures and avoid machine work
Try to buy a used power FC for redtop L-jetro from ebay for $500~
Dont buy expensive EMS systems that you will totally lose your @$$ $$
Focus on cleaning and maintaining the engine you have if its in good shape
If you can't tune a PFC then maybe find a place to rebuild the stock turbo (sometimes that works) for like $60 or something, then use back all the oem electronics.

At all costs avoid expensive engine managements and used turbos and machine work.
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Old 08-20-2019, 10:36 PM   #3
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Dodged a bullet


I was finally able to get the car towed to a location with enough space to start working on it again.

Task 1: Compression test
Car has been sitting for 3 years so I wanted to warm it up for the test.
After Draining the gas tank, changing fluids, plugs, belts, I decided to start her up. Started right up, and after warming up a little the idle seemed a little off. I pulled the plugs and noticed 1 plug was wet. So I swapped the extra coilpack I had laying around and started it again. This time the idle was perfect and ready for the compression test.

Results: 150-150-140-150 (cylinder 2 was the bad coilpack)

Cylinder #3 is within range, and I had a good feeling it was a valve not seating. After another oil change and a couple warm ups I tested again.

Results: 150-150-144-150 Pretty happy with that.

Even with all that the car still did not want to rev smoothly same Maf/Injector issue as before not to mention the stock ecu with unknown tune.
So I ordered a Megasquirt Pnp2, and 4 new coilpacks. Installed everything with no problems. Changed the injectors settings, deleted Maf for Map, and so far I couldnt be happier. I have not gotten the chance to get it tuned on a dyno, but have done some basic idle & street tuning with my wideband.

My suspension is pretty old so i'm currently waiting on new coilovers before I make any hard pulls or take her to a dyno.

All in all I got pretty lucky.

This time......
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