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SignUp Now!Originally posted by ijames
P.S. When I did this before I got 197.2 for the constant but I think 196.9 is more accurate (sorry, Jim Testa). My new estimate for Tim's car is 487 rwhp.
Originally posted by JDEstill
Hey Carl & Dave:
The problem I have is that both ways give the same hp. There is a disconnect somewhere! I wonder if Joe's spreadsheet is wrong... But it seems more likely to me though that the hp calculators can be easily fudged to include driveline losses (and therefore give flywheel hp).
Anyway, let's take a look at Dave's car. I like his since he has documented it so well.
Dave says he is moving about 180 x 2 = 360 gm/sec of air. Assuming an a/f ratio of 12:1, then he needs about 238 lb/hr of fuel. That gives an injector duty cycle of 80% with 50 lb injectors (is that about right Dave?).
If Dave sees a BSFC of 0.5 then he is making 475 hp with that 238 lb/hr of fuel. Which corresponds nicely to Lubrant's sheet for a 117 mph car. The sheet also shows that such a car needs a 50# injector @ 80% DC to run that number, which jives with the above.
That all seems nice and consistent to me. Now if Dave was really making 625 flywheel hp with that fuel flow (ie the 475 is rear wheel hp), his BSFC would be 0.38, and *that* is what does not seem realistic to me. If the above is wrong, please show me where!
John
Originally posted by TurboTR
PS John, maybe you can throw some of the FAST ecu numbers into your spreadsheet and see if it calculates matching air for 72's at 88-90% duty and about 11.6:1 a/f? I think we had about 85% VE, 28 psi boost, air temp about 130 deg, RPM about 6300.
Originally posted by TRDirks
I did get a chance to play around some today. I lowered my WOT setting to "0" and upped the fuel pressure from 45 to 50. Bob+Carl suggested this to help let the computer control the fuel since I was way over static the way it was set before. I am running pump gas now so I cant reference this to the 20psi run at the track but my initial post/readings were at 16-17 psi so thats what I did today. The numbers I am getting now are lower than before with a max of 184 compared to prior settings when it was 213. So it is about 16% lower than it was before meaning my 20 psi run should bring MAF #'s in the 219 range with the switches set as they are now. This still doesnt jive when referencing Dave's car though since the flow is similar when I am 10 psi lower than him. Anywho, it looks as if I have made a move in the right direction and if any one else has any other ideas let me know and I will give them a shot.
Also I hooked up my TL boost sensing cable to a 3 bar map. So now I have boost sensing for Directscan. Has anyone else done this? I'de like to swap some info in relation to the boost/temp readings at certain levels.
Thanks
Originally posted by TRDirks
I am running pump gas now so I cant reference this to the 20psi run at the track but my initial post/readings were at 16-17 psi so thats what I did today. The numbers I am getting now are lower than before with a max of 184 compared to prior settings when it was 213. So it is about 16% lower than it was before meaning my 20 psi run should bring MAF #'s in the 219 range with the switches set as they are now.