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That calculator is based on averages from Edmunds...nowhere to factor in things like gear ratios and tire size.
A more accurate 0-60 is 6.3-6.5s according to a numerical ODE solver that does factor in all these variables (if anyone wants to see the MATLAB code I have it...I can't take credit for it though). I entered tire diameter based on the 195/165/R16 tires you are running, the gear ratios are pulled from Clark's Garage data for a 924S, the drag coefficient * frontal area = 0.647 m2 according to Wikipedia for a 944S (closest I could find, from here). I assumed a 0.7s average shift time, code assumes starting with the car in first and no wheel spin (doesn't account for clutch slip). Imported a Spec 944 dyno power and torque curve and adjusted for your expected power and torque. Used 2266 lbs weight. Again I'm happy to show the code, it's based on a Runge-Kutta numerical ODE solver and was a major school project for the numerical methods class at Baylor University that all students had to complete, he got an A for this.
Code:
"The time required to go from 0 to 60 mph is: 6.5122 seconds.
The time required to go from 5 to 60 mph is: 6.2788 seconds.
The time required to go from 30 to 70 mph is: 6.6055 seconds.
The time required to run a quarter mile is: 14.6582 seconds
at 93.05325 mph"
I said as low as 6.3 to account for a slightly lower CoD, maybe lower shift time, and maybe +10 hp. Also shifting higher than 6200. You are still over 6 secs until 200 bhp or so.
and why are you getting onto me for saying "we?" I mean people who have already worked this out in the past. Most people understand basic physics. Nobody here is on a high horse, you're being antagonistic for no reason. You're asking a lot of questions and getting mad and frustrated when you get replies. At this point it's damage control to offset the misinformation you are posting. fml.
Nice pretty graphs, don't waste your time on this new Subject brought up by Voith, I'm not arsed if it's 5 , 6 or 7 seconds to 60
.. get back to the afm questions.......
R
I've done one of my MScs in England, in Cranfield. Title was: MSc in Computational Fluid Dynamics. I've been working as a simulation solver developer for the past years.
Will you believe me if I tell you that the "barn door" hinders air flow?
I guess not. It doesn't make it any less true, though.
Basically, it acts like an orifice decreasing the cross-sectional area which introduces a pressure drop before and after the orifice. That is a hydraulic loss.
Yes, this is not a problem, when the door is fully open. But at that point the device does not measure anything, it only says "more than what I can measure".
Yes, it slows down throttle response below 4500 rpm. Whether one can feel it or not, I can't say. Depends on how good the driver is, I reckon.
Yes, best would be to get rid of the square opening as well and have a constant diameter circular one instead, a la Augment's big bore airbox.
Edit:
Yes, Porsche will totally put it in even if it's restrictive. Here's why: because you need to measure air flow to be able to control fuel injection. They chose the AFM + Motronic because it is better than a carburetor. (Some might disagree, though.)
If they had access to more modern measurement devices, be sure they would have used that. Like how they ditched the AFM for the 968. Or is that already on the "newer things are just there 'cause they're cheaper not because they're better" side? Then you should convert back to a carburetor.
Or explain why the AFM is best? The sensor that is a restriction in the lower half of the rpm range and cannot measure at all in the upper half.
Im going to say 152rwhp, so about 188 crank. The same as my 944S really. She will drop off pretty hard after 5500rpm due to airflow restrictions in the intake system and the natural limits of the heads. Even ported they don't flow nearly as well as the 16V stuff. Your cam will help make up for some of that along with the porting in your heads, but the stock AFM will limit your gains.
I still maintain you would have been better off swapping a 968 engine, I say that because i DD my S2 with one swapped in it its pretty great even at 6,000ft. Its much quicker than my 924S and 944S were and i never want to go back to the other 944 motors. You have less weight but i don't think you'll get under 2450ish on the car even fully stripped.
Im going to say 152rwhp, so about 188 crank. The same as my 944S really. She will drop off pretty hard after 5500rpm due to airflow restrictions in the intake system and the natural limits of the heads. Even ported they don't flow nearly as well as the 16V stuff. Your cam will help make up for some of that along with the porting in your heads, but the stock AFM will limit your gains.
I still maintain you would have been better off swapping a 968 engine, I say that because i DD my S2 with one swapped in it its pretty great even at 6,000ft. Its much quicker than my 924S and 944S were and i never want to go back to the other 944 motors. You have less weight but i don't think you'll get under 2450ish on the car even fully stripped.
Agreed. If you have all the glass on your car and steel fenders, there is NO way you are getting anywhere near the 2200 lbs you claim. I repeat, NO WAY you lost 500 lbs. I know this because one of my cars (the turbo one) is totally stripped, manual everything, literally everything non essential removed. 1 light weight race seat, no center console, no heat even. It still weighs in at well over 2550 lbs.
I'll answer the question. I predict you won't make over 165 rwhp (~188 crank) and you stand a ~20% chance of grenading the engine on the dyno because of a poor tune
He did change all the fenders to fiberglass and all the windows (except the front) to lexan, so I do not debate his claims of weight loss.
Actually, I love his build, like I kept saying in his original thread, but he got really tangled up with this AFM topic. I guess it's going to get better the next time he discusses it with his engineer, maybe that chap doesn't know yet that there are plug & play replacements.
He did change all the fenders to fiberglass and all the windows (except the front) to lexan, so I do not debate his claims of weight loss.
Actually, I love his build, like I kept saying in his original thread, but he got really tangled up with this AFM topic. I guess it's going to get better the next time he discusses it with his engineer, maybe that chap doesn't know yet that there are plug & play replacements.
Well spotted ! At least someone is on the ball....
02-04-2016, 12:05 PM
