2000 sentra +Sr20De(t) = antichrist

[Baldturbofreak]

Hello,

I have been slaving over this 2000 sentra that was brought to my shop some time ago for engine managment.

It had the Sr20det already in it, done by one of, if not the BIGGEST hack on the planet. Something told me to run, but I took pity on this kid..

I installed a greddy E-mange ult along with LC-1, greddy map sensor, etc.At the same time he had me install the sending units for a bunch of guages he had some stereo shop put in.First of all I cant get the car to run worth a shiesse. Come to find out that if you try to intercept MAF signal at all the PCM goes into limp mode.Figured that out and got the car to at least warm up and idle.- It has no oil pressure. Take the pan off the car and the entire bottom of the oilpan and the pickup tue for the pump is PACKED with BAMBOO!!!!! (WTF smugglin pandas?)I pull a rod cap and trhe bearings look horrible.At that point I told him the whole motor needs to be gone thru to make it right. I didnt have the time or manpower and he needs to pick it up.1 year goes by (IM not kidding he abondoned it in my parking lot)

I finally get ahold of him and he begs me to straighten the whole car out (huge undertaking). Like a dumbass I cave and take the car apart.

The DET block has had some a$$ sawzall and grind the mounting lugs for the jackshaft mounts. when Igot the last bolt out the thing sprung over 1.5" (not kidding). The guy took a bar wedged the shaft and welded it there. ****kin hack!!!!!

At this point I tell the kid to bring me the DE block and I converted it (bedpan, block girdle, Turbo lines,etc) to DET spec.I filled the block with 1) new crank2)BC H-beams3) wiseco slugs -8.5-14) BC cams for non-roller5)BC ex valves6) ported lowport head7)stock DET turbo +mani8)some ebay intercooler +piping

To get the non-roller cams to work you need non-roller cam valves (.158" longer tip)The intake side had the stock valves so Im trying out the BC non-roller cam on roller valvetrain- so far no problems.

after many issues with hackjob crap all over the car I get it straight. Or at least mechanically right.

here's my issue with the car ....

It has a z32 maf, and I cant alter signal. So it's feeding off a lowload/high ignition lead part of the factory table. When I have likely 12 lbs/min going thru the motor, the z32 is telling the factory PCM there is only about 7lbs/min goign thru. The factory PCM is commanding 35deg of advance!!!at only 4KIn order to get enough working room with the timing Ive had to retard the Dizzy so far that I had to elongate the slots with my CNC. Then add the timing back in under no-boost. I cant get more than 13psi into this motor without it rattling like a SOB.190whp is pretty sorry for what I had expected, even for my dyno (Land and Sea Dynomite, about same readings as a mustang dyno)It also peaks at a low 5800rpm, but never losing more than 10hp up to 6700 rpm fuel cut. When our GXP was bonestock it made more than that by 10hp.

Ive got a feeling that it stems from the engine management. I think the stock MAF really need to be back on there, at least so I can get the timing back to where it should be.

This is my first (and likely last) Nissan build. what do you guys use?In the GM world we can get into the ecm, give it the proper voltage vs airflow map for any MAF and we're in biz. With this car it seems like all I get is a box of bandaids to work with.

SR20 guru's what kind of power do you usually make with a similar setup?What do you use for engine management in this chassis?

Extremely frustrated,-Rick Gifford.

[nametakennow]

Piggyback + big injectors (which I assume you're using the ones from the DET, which will do) + FPR is the most common setup. Rerouting the MAF signal through something like an SAFC works fine. It's only +-50%, though, so your only shot is some trickery with the FPR, and I'm not certain that will work.

By the way, I hope you have a high flow pump. Otherwise you're starving it regardless.

If you keep the Z32 MAF, there's a different set of issues that I will have to look up and get back to you on.

Anyway, this setup should yield more like 250whp.

[Baldturbofreak]

So you are saying you folks have gotten the 00-02PCm to play ball with the MAF signal altered.It seemsed like no matter what running it the the EMU caused limp mode.

A bone stock GXP makes about 205whp so Iguess it's really not that far off on whp. maybe about 10-20 down from what Im expecting. Seems like it should have carried right out to redline. (6700)

Yes she has a walbro 255 in the tank. also, BC springs and TI retainers

[nametakennow]

How about the FPR?

00-01 PCM/ECM/ECU, 02 the SR model went away. I ran the MAF signal through an SAFCII with no problems.

The turbo isn't big enough to keep making more power that high. It's a very mid-range power engine, and the turbos Nissan put on enhanced that aspect.

[Baldturbofreak]

Heres is the best run before pre-ignition. The power curve doesnt look ugly. No KR spikes, no valvetrain issues. The Egt's suggest that more timing would enhance cyl pressure but it has seems to have A real octane tolerance issue. I can hear the preignition before it shows up in the datastream. Im ready to put a damn megasquirt in it. It just seems like there should be more power,even for a Gt2554. Perhaps the TIP is really really high and the cam overlap is alowing excessive reversion into the combustin chamber?But that's the same as EGR, allowing inert products (burnt A/F) into the chamber actually increases octane tolerance. need more data I guess.

Whats the coldest plug that can go in this motor?

Fuel pressure is remaining constant 1:1 with vacuum/boost as it should. engine idle/novac pressure 58psi. The extra bar is calculated into the injector constant/opening time Via datasheet.

For comparison's sake a stock Sr20DE with 140hp would put down about 90-95whp on my dyno. It's very stingy. (Better than blowning smoke in your can and giving you a number your Et/mph doesnt support)
Modified by Baldturbofreak at 12:54 PM 2/10/2008

[nametakennow]

Your dyno is stingy, wow.

Honestly you've gotten a little beyond me on the technical info. I do know that the SR doesn't like super cold plugs, but I don't know what exactly. I do know that people often end up switching back to stock plugs.

What's your A/F ratio like? Past 12:1 turbo'd DEs tend to detonate a lot.

Grab the FSM from the link in my sig if you don't have it, it may help you do some comparisons on numbers you're getting vs stock.