Thread: Low dyno numbers on full bolt on 97 SE-R. 138hp. Input appreciated

Last week I took my '97 200sx SE-R to the dynojet to see what it was putting down. I was expecting you know, 155hp or so. What I got was 138hp and 120ft lbs torque. Here are the mods:

Cold air intake
OBX 4-2-1 header, 2" downpipe
Tomei 270 degree "pon-cams"
JWT ECU POP program w/ S3-S4 cam program
2.5 " cat-back exhaust to Dynomax "drone-free" muffler
G-Spec underdrive crank pulley
Timing @ 19 BTDC
Exedy stage 1 racing clutch

The motor is the original SR20DE, 188k on it. To be honest, when I first pulled the valve cover (I bought the car on Craigslist back in 2011 from a girl who knew nothing about it for a good price) it was a sludge monster. I did a bunch of motor flushes and switched to Mobil-1 synthetic. The motor also has new NGK spark plugs, new spark plug wires and a new valve cover gasket. From all I can tell, the engine runs well and feels like it pulls as it should. It was right with my friends 96 SE-R with almost the same bolt ons in a brief 0-60 jaunt. But here's the thing, I have the JWT ECU with the S3/S4 cam program (stamped on the ECU) but I have Tomei cams in the car. To date, no one has been able to give me an answer if that is good or bad, or won't matter, except of course, when I called JWT and asked, they tried to sell me the S4 cams, lol. My timing is set at 19 degrees. I once had a 150whp 98 Sentra SE, years ago, and it feels about the same in terms of acceleration. But obviously the dyno numbers are saying otherwise.

Then the day after the dyno, the car ran like crap and I pulled the ECU code, and it came up with cylinder misfire code. I replaced the spark plug wires and everything was fine. I remember I thought perhaps one was just loose, so with the motor idling like crap, I pushed on the wires at the distributor, and I got a mild electrical shock. That was the last time I tried that. The ECU has also been throwing the front and rear 02 sensor codes since I had it, I have no idea why. They were replaced but the codes remained after a couple starts.

Anyways, I don't know what to do. The car has the OBX header with the 2" downpipe but then has a 2.5" cat back exhaust to a dynomax muffler with a baffle broken inside of it (lol). The Tomei cams were installed properly, I didn't skip any teeth or anything, in fact, I spent about 4 hours double checking everything because I am OCD about that shit. No vaccum leaks that I am seeing. No I haven't done a compression test or anything of that sort yet.

Also, here's a weird thing about these dyno runs. The highest HP run came during the 4th and final dyno run. The first 2 runs were so low I don't even want to mention, but each run the HP #'s went up 5-6hp or so. I wonder if I did a 5th run if it would have been 143hp-ish. Or if it was just a coincidence. When I dyno'd my VE, the 1st run, 206hp, was the highest. Each run after the numbers dropped to as much as 196hp.

Sorry for the length, but I'm sort of baffled by this. Any help would be appreciated.

What were the afr's like on the dyno. Have you ever done a compression test on this motor. Being that it was a sludge monster I would expect extra wear.

Those 2 are next on the list of things to check out. I just emailed Ben @ JWT again to see if he says my numbers are low because I have the S3/S3 cam program and Tomei cams. lol

have you done a compression test?

also, they do not have Pon cams in 270 degree's. Pro cams yes and iir they require solid lifter.

They say 270 degrees on the boxes that I got them from. Car runs good.

I made 150/135 on my de.
-homemade intake
-ssac header
-2.5 inch exhaust
-19 degree timing
-gspec pulley
-msd ignition
-msd coil
-s3/s4 cam combo
-stock edu

i made 140 with 260 tomei's and 15deg. could be those "super rare" hydraulic cams you got in there.

i duno about the jwt tunes but most tunes run best with a base timeing of 15deg btdc???? so i would reduce the timeing reset ecu and see how she feels with a good blat round the block...pro cams are 270 pons are 260 or less, I have the 260/11.25 pon cams and pulled 260whp on a nz dyno

Cold air intake
OBX 4-2-1 header, 2" downpipe
Tomei 270 degree "pon-cams"
JWT ECU POP program w/ S3-S4 cam program
2.5 " cat-back exhaust to Dynomax "drone-free" muffler
G-Spec underdrive crank pulley
Timing @ 19 BTDC
Exedy stage 1 racing clutch

Could it be it is just not tuned to your set up? I think this could be pretty important.

If the Tomei cams are the same specs as the S3 or S4 cams from JWT, that shouldn't be a problem IMO.

The fact that power increased throughout the 4 runs is indeed interesting, as you would suspect it to be the other way around (heat-saturation of parts).

About the O2 codes, have you reset the ECU at all?

Also, a 2" DP sounds a bit small for a car with bolt ons. ESPECIALLY with cams. I mean, you're making more flow with the upgraded cams and such, so I would assume you would have to upgrade the exhaust to a larger diameter. And for a N/A car that would mean larger than 2.25". Exhaust flows only as much as the smallest diameter would allow. I mean, a 2.25" catback would choke a 2.5" downpipe. And a 2.5" catback wouldn't make a big difference on a 2" downpipe.

I would try fitting a larger header, and see if that frees up power.