PSR 4849G (G25-550 Clone) Built Motor Pump 93
 

The car is a 1999 NB1 with a built motor. Specifically, a 1.86L BP4W (non-vvt) using Wiseco 83.5mm 8.6:1 pistons, +1mm I/E valves from Manley, Squaretop manifold, Skunk2 TB, Kraken 3" exhaust with a side-mount manifold, PSR 4849G (G25-550 Clone), FF960 injectors, Stock Fuel system Fuel Pressure regulator, Walbro 255lph fuel pump. Using Open Loop Boost control on a MS2PNP. Running a 6-speed transmission with the stock 4.34 rear end. I've got a 3.63 ring and pinion to rebuild the diff with, but I haven't gotten around to it yet.
https://cimg3.ibsrv.net/gimg/www.mia...d78d67a78b.jpg
These pulls were back and forth on the same road, and in north east Tennessee, its rather hard to find a flat road. So I usually will do a handful of pulls up and down the flattest road near me and take the middle graph as the most accurate numbers. Also, out of curiosity I did a pull in 6th gear from low RPMs to see when the turbo would spool and it ended up spooling to 14psi by 3400rpm and 28psi by 3800rpms as shown by the yellow line (28psi boost cut). Boost controller duty cycle was the following (I'll do more spool optimization/preventing boost cut next time I get out and tune):
https://cimg4.ibsrv.net/gimg/www.mia...06652f397b.png
Ignition Table (only tuned to 228kpa then past that it is extra conservative). I'll probably end up taking another degree out of the 228kpa line, although I've already taken 1.5-2 degrees out from where I just barely could hear knock at peak torque while listening to the stock knock sensor through the MS2's headphone jack.
https://cimg6.ibsrv.net/gimg/www.mia...acb876e6c4.png

Stock fuel system, so that's still on the OEM fuel pump or similar? I just wanted to double check because I've read differing opinions on what the stock pump can handle.

Nice looking graphs! When tuning your ignition table (assuming road tuning) did you adjust the boost controller to hold at certain boost levels and tune each row, or was it mostly at 228 KPA and then interpolating?

That seems like a lot of timing at 228kpa on pump gas, but sick numbers! Peak torque at 4.5k is pretty nuts too if those numbers are close to accurate. G25-550 seems like a serious performer.

Agreed on the fuel system. No way that’s a stock pump haha.

I've heard the stock pump is capable of running around/over 300 hp for some people. Not running E85 might mean that he is indeed on the stock pump.

@Z_WAAAAAZ Did you ever hit the limit on your stock pump or your dw200? Or did you just upgrade for E85?

In for results on this fuel pump debate haha. I was under the impression that the stock fuel pump was good into the low-200s on pump gas, but results varied because so many of the stock fuel pumps still in these cars were old and tired.

I only upped to a DW300 because the 200 wouldn't have enough flow for the eventual 350whp on e85 that I'd like to run. Never had issue with it at 270whp on 91 octane. Not sure what the limit for that pump is on pump gas though.

DW200 can support 500whp on pump easily,
350whp on ethanol no problem, too.

No idea if anyone was brave enough to run a stock pump at 300whp+

Did I say 350? I meant 400 haha... :x:

Thanks for the numbers, DV. I swear I'll contribute to the 50-75mph thread this week/weekend.

@Watterson02 Would you be able to confirm if this is on a stock fuel pump? I'm still curious about that.

My apologies, I thought I already replied. The fuel pump is a Walbro 255lph. The limiting factor is the FPR since on the NBs it’s only a static 58psi at the regulator which is located at the tank. Can’t comment on the limits of the stock pump. I replaced it when installing the forged engine.

Gotcha, thanks for the reply. I'm currently on a DW100 so I'll be interested to see if the 2560 maxes it out.

With a DW100 you will be running out of pump before running out of injector. It MAY be possible to reach your goal, but your FP will be working it's *** off, better get a DW200, they are like 100$?

Good numbers. Your timing map for the rows above 228kpa need a lot more timing imo. Although if you only have 93 you're limited by knock etc. I would have to go back and look at my timing map but I have a similar build 8.6cr etc. What manifold are you running? I know when I went from the FM old style log to a newer kraken low Mount I was able to add 2* more timing just from the reduction in back pressure.

I believe I was making 330-340whp on 19-20psi on pure 93 octane and I capped the boost there for pump gas and when I wanted to run more I added vp octanium which brings 93 up to 100-101 octane. With the VP stuff I can get over 400whp and I can run decent timing Numbers at 24-25psi on my 2867gen2. Like you I have a walbro and still using the stock fpr. I run 780cc injectors with a radium rail, I think at 25psi I'm over 90% duty so that was the limit for what I could achieve with my car, which is fine bc you'll break 6 speeds quickly with that power.

I might go back and look at my timing maps for 93 if you're interested. I spent the better part of 2 years perfecting it and I run a very very similar build to you.

I just looked at my 93 map and I don't really run much over 21psi on pump so my rows above that are sorta irrelevant bc I don't use them. At 19-20psi I'm running 17-18* of timing at the top end with 12-13* at tq peak and coming up from there which is pretty similar to yours.

That was the plan. This was done when it was still rather cold out, so before I messed with ignition timing I wanted it to a little warmer so that it doesn’t suddenly begin to knock when the IATs are 30-50° higher. I plan on doing so the first day I’m available and we have good weather. Maybe this weekend.

also, I’d love to see your high boost pump gas timing map. I couldn’t find very much online to check that I was around where I should be.

Good to know that I’m in the right ball park at 18psi. I just haven’t addressed ignition timing above that. Also, I tuned it on shitty Walmart 93 octane, hoping that the better Shell gas I plan on running will give me an even larger safety margin. I’ve even fooled around with the idea of throwing a gallon or two of the 108 octane race fuel in the tank every time I fill up at the shell station to run some more ignition timing if I couldn’t get out of the single digit of timing at full boost.

edit: I just realized you posted both of these comments. I thought I was replying to two different people haha

I got to run the car at the Bristol Street Fights a week or so ago. It was super busy, I got there late, and then had obligations that made me have to leave early too. For the tune, it was still around 26psi, but seemed to peak at 27 in the longer gears. I ran a ~96-octane blend of 93 from Shell and 2ish gallons of leaded race fuel. I was able to give it like 2 more degrees of ignition timing on top of the old tune. I suck at launching the car and I was only able to get a 2.204 60' within 3 runs (the others were 2.5s LOL). Regardless, I ended up at 12.530 seconds @ 117.45 MPH. It was 8.321 seconds @ 93.78 MPH in the 1/8th that pass. I'm hoping to do better this weekend...

Does anyone have any tips on how to launch the car better? I'm running a 6-speed and launching in 2nd gear. I dropped my tire pressure to like 24psi on the 245/40/15 Falken RT660s and set the launch control to 4350rpms with fuel cut (would even less tire pressure help?). It would leave the line without boost while I tried to ride the clutch, and then it would come onto full boost and just spin the tires before I got into 3rd. Once in 3rd gear, everything went well other than the fact that I hate the 4.3 rear end with the 6-speed. Crossing the finish line close to 6500rpms in 6th gear feels so wrong...

Should I set it to spark cut and let it build boost on launch control and maybe lower the RPMs to counteract the newfound torque? Maybe try 1st gear for launching? I have been thinking about doing a weird boost table so that from 50-90% throttle it is only wastegate pressure, then launching it in first without going full throttle. I'd also have to set my launch control to work at like 50% throttle or higher for this to work well too.

You could try lower tire pressures, I've run all the way down to 13-14 occasionally with my hoosiers. You may not be able to get quite that low, but maybe 17ish or so unless you feel any sway in the rear at higher speeds, then you would have to go up in pressure.
Also some traction compound like vht or trackbite might help. You could also try adding 50-100lbs weight in the trunk in the most rearward section of trunk you can. Might help to disconnect front sway bar too.
However a good set of slicks or at least drag radials may pick you up 4 tenths in the 1/8th with an additional 1 or 2 tenth improvement on top of that over 1/4 mile. Wont help trap speed a whole lot though. That small turbo might be holding that back a bit.

Alright, I'll experiment with going lower on my tire pressure next time. I wasn't sure how low was too low. Not sure I want to add any weight or mess with sway bars, but I appreciate it nonetheless. Once I get around to rebuilding my diff with the 3.63 gears and simultaneously reinforcing it, slicks + upgraded axles are 100% on the to-do list.

I'm not sure where the turbo is at in terms of capacity. I know it can hit 29 psi at any RPM range, but my fuel system just can't support that in the higher RPMs. To really find out the limit, I'd need to upgrade my FPR or go to even larger injectors, which is only a bandaid fix since the real problem is the stock NB FPR. regardless, I believe I'm happy with the power the car is making currently. I don't want anymore until I can afford a transmission swap to something stronger. Also, I've not messed with the timing on the VP Octanium yet, only the 96-octane leaded race blend. I should be able to get to 400+ whp just with ignition timing if the octane rating really goes up to 100+ with the VP stuff. On the 96-octane blend, it was showing around ~375whp.

50-100lbs sandbag in the rearmost part of the trunk may surprise you.

I run about the same tire pressure as your boost pressure, 26 I think, whatever it says on the door jamb.
I launch in 1st, at 5 to 6k, revving without launch control. Wet burnout works well with these crappy continental tires. Trunk full of tools, snacks, and a full tank. I can pull 1.7 60's.
Maybe you should watch one of my videos. 4.3 sucks with a 6 speed, but not enough to start in 2nd.