If you guys are so good at that how about one that gives new injector ms setting for increased presure?
If you guys are so good at that how about one that gives new injector ms setting for increased presure?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Do you mean injector pulsewidth? That is what I rely on the PCM to figure out. From looking at some of the adders for AE and PE, I am pretty sure that it calculates it in microseconds instead of milliseconds though.Originally Posted by EagleMark
If you mean injector latency due to increased pressure, there are way too many injector specific varibles to be able to make up a blanket calculation for.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
Wasn't sure what to call it, seems like differant ECM have differant names.
I'm working on a 440 Mpoar bored .030 over and undersized cam. It was an origanal six pack engine.
Using the spreadsheet I come up to 15 PSI. not a big differance to the 13PSI stock. Any ideas if I should change this to start?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
If the expected hp output is a little more than the engine those injectors originally came in, then sure, I would set the FP to 15 and go from there. It's really just a starting point anyways from my experience. With that small of an increase latency won't really change any measurable amount either.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
Just another Injector sizing program...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
This is a calculator I find quick & helpful,
http://www.gtsparkplugs.com/InjectorSizeCalc.html
An easy overall fuel requirement formula is HP*BSFC=lbs per hr.
Another calc I really like was posted on Sean's site,
Last edited by lightning-jr; 12-14-2011 at 10:28 AM.
One of the biggest things I have had trouble with, is how do you figure out injector size and pulsewidth when you have no idea how many HP your engine is making?
79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy
93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver
99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.
Stock engines should be close to whatever the EFI conversion equivilent is. 304 AMC = 305 Chevy. Add a part and they usually tell you the increase, change a cam and they do give specs. It's all to get close, then tune!
It was wrong to change BPW just to try and add fuel. I tested it and it failed. So I did a lot of reading and came to same conclusion I did long ago when starting a tuning project on a built engine.
1. First you have to know approx HP engine will acheive.
2. Then need to have injectors and pressure to meet that HP number.
3. BPW or BPC is specific for injector size-CID- Fuel Pressure.
If you have enough fuel to cover WOT high RPM of built engine then the BPW or BPC should stay the way you calculated it. Then work on idle
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
I found an online calculater that should get you close if you know your cam specs or have a proven engine build crate motor you should know exactly.
http://www.bgsoflex.com/roughhp.html
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Intresting link. Have no idea what my compression is either...lol. Stock I think was 8.8, minus 20thou, mabey 9 now?
I put in 409 cid (since its 40 over) and 9 compression, it says 301 at 4500.
My cam is the comp cams XE256H
79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy
93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver
99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.
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