cliffyk

The injectors really need to be sized to your anticipated power level.

Assume the following:

design goal: 450fwHP
fuel pressure: 40psi

42lb/h injectors in this scenario would be operating at 80% duty cycle at maximum power. A nice place to be--far enough into the output curve for solid control, and still having a good overhead--and idle and low load operation would be well up in to the injector's accurate delivery range.

60lb/h injectors in this application would be operating at 56% duty cycle at maximum power. While at maximum power this would be acceptable, the obvious compression of the injector's overall operating range will create idle and low load driveability issues as fuel delivery at shorter pulse widths becomes less precise and consistent.

While some of this can be tuned out, why not eliminate the concern by using properly sized injectors.

Also, 42lb/h injectors will support any power level that the stock bottom end can handle (500fwHP/425rwHP at 40psi, at 90% duty cycle). If you decide to go beyond that, upgrading the injectors will be likely the cheapest part of the project; and you'll be able to sell the 42s for enough to soften that part of the deal...

Bman2000

Thanks cliffk that's what I was thinking, I can only prep so far ahead before driveability becomes issue. Don't we need stand alone to get the best tune after 42# injectors, somthing with the comp not being able to do it as precise? Any idea the parasitic loss from t-56? Its be a bummer to get 425rwhp and be to much for motor

lizzyfan

12-15% on a manual trans

cliffyk

^+1 on the loss, you can't get numbers any closer than that due to the lack of generally available information and a whole slug of variables.

The PCM power limit is that it can only deal with 1740kg/h (3830lb/h) of incoming air; beyond this you have to scale the MAF curve, injector settings, and standard air charge. This limitation is represented in these MAF curves by the horizontal dashed line.

That 3830lb/h, if you pushed right up to the limit, would support 530fwHP running f/i--450 or so at the wheels.

Bman2000

then after that everything has to start being scaled, which can create other problems in drivability right? Oh and so basically with the t-56 if i get 425rwhp just call it good like i would with a 5 speed? since there is no prefect guess without a direct comparison...bummer lol

cliffyk

The scaling, if properly done, will create no driveability issues, other than those to be expected when you get to/go past 100HP/liter.

The transmission has nothing to do with the engine's limitations, however at 425rwHP you are flirting with the upper limit of the 2V block's capacity. If you are a "***** and all" guy who doesn't mind blowing an engine go for it--OTH if this is your DD and spending $3500+ on a new motor might be a problem, then I'd keep it at less than 400rwHP--or have a bit of constraint and not consistently push it to the limits.

Bman2000

ok, i always thought that 425rwhp was reliable limit, not borderline lol. good to know. its not my dd anymore. so a broken motor would suck and put me down for a long time but not keep me from getting anywhere.

Hey i have a question for you. you have much exp. with hydrolic clutch set ups? cuz i have a friend whos having pedal problems, on full throttle the clutch pedal drops almost to the floor, still can disengage, but barely. Works ok doesnt have grip problems comes back up when hes done. Says he bled it, i thought he was pinching the line, but when he moved the line he says hes still having a problem...any ideas? sorry if this is a bit out there, just appreciate the knowledge.

Gt04

I don't have any driveablility issues at all with my 60#s....

Bman2000

Wasn't saying it was a gaurenteed thing to have drivability problems, there are plenty of good tuners that make it work, I'm just not sure I have any in the area

Bman2000

hey are the lightnings ev1 plugs too? cuz i found a dyno used set of 42# and just wanted to make sure, he said they are ev1 same as on a lightning. trying to get a part number just to double check, id hate to buy the wrong kind.