Hey guys, just got back from a best-effort tuning session to try to get some street manners out of these 160lb/hr injectors and did a few WOT pulls as well.
The good news:
The car makes 600ft-lbs/[email protected]
(SAE, rear wheels) at 11:1AFR with only 16deg total advance on piss gas with the graph showing indication that the spark is far from optimal. And, it looks like it barely reached peak torque (we think). With all that retard it may come later though. This shows promise for being able to hit my 1000fwhp (850rwhp) dream.
Matt Robison came out unexpectedly; that was a pleasant surprise, thanks for making the trip Matt, nice to meet you!
The bad news:
Drivability sucks; the 160's simply won't cut the mustard at cruise. The pulsewidth is so small (1.0-1.3ms) that I'm flirting with the injector offset vs battery voltage function which is causing the tuning experience to be a lot like trying to balance a ball on the point of a pin. Once you crack the throttle open and get off the injector offset floor, they behave linear. But down in the closed throttle region, they are far from linear and far from reliable.
Maybe they'd work better on a bigger engine or a drag-race only deal; but for something I want to enjoy on the street and road course, this isn't going to cut it. Getting beat to death just driving down the freeway is not terribly pleasant.
I tried locking the fuel pressure and eliminating the bypass valve from the equation...neither helped. I tried everything between 24 and 40deg of part throttle spark; didn't care. I can get it to idle nice/lean, and can get the drive tune close...but it still bucks and heaves and acts snotty and suffers from calibration drift regardless. In fact, with the throttle constant, the mass flow constant, fuel pressure constant, and the injector pulsewidth and spark advance from the EEC constant, the engine rpm will surge up and down at cruise all the while swinging the air/fuel ratio between 17:1 and 11:1...which can only be caused by fuel. I really don't know if it's the injectors themselves or the driver box...but I'm going to take an educated guess that it's the injectors. I know for a fact that the minimum pulsewidth it takes to get one open is somewhere around .8-1ms when the injector is cold. I made a test jig and tested this on the bench with 40psi of fuel pressure on them. Since my cruise pulsewidth is only 1.3ms...I bet that is the problem. I'm trying to work with 0.3ms of pulsewidth and the injector offset probably moves around a little due to heat, voltage, etc, making it a very hard target to hit indeed.
Anyway, as you can tell I'm frustrated.
Next step; order up some 83lb/hr siemens dekka injectors and give it another go.
Car sounds great a WOT though and sounded like things were just getting good when I hit the purposely low-set limiter. The fuel system seems to be cutting the mustard, the dash system worked as planned, so all in all...not a horrible day. I found a new oil leak (back drivers valve cover) and oh yeah, the 20w50 did the trick in the oil pressure department. I was seeing 60+psi of pressure at 5K, and 25+ at idle, hot. Additionally...with all this beating on it and no supplimental fan, the hottest the engine ever got was 170deg F. Apparently my cooling system is sufficient.
That's all for now, more later as I get the bitch to run right.