RC-F dyno...
12-11-14, 05:52 AM
#16
Pole Position
Low end is where you want to go with the street cars. Diesel thrust and fuel economy is coming to petrol engines quite soon. Soon enough all of them will drive like diesels do today and use as much fuel as diesels do. Heavy knocking will be included in the package as well.
12-11-14, 09:30 AM
#17
Lexus Champion
Nice throw in a JoeZ exhaust and intake your looking at 408 + to the wheels (20+whp) with the combo.
12-11-14, 05:42 PM
#21
I don't know about HP being completely meaningless, how does a Porsche 911 GT3 with 475 HP and only 325 ft lbs of torque run a pretty even 1/4 mile race with a Z06 with 505 HP and 470 ft lbs of torque, with both weighing about the same.
This has been discussed e xtensively in another thread. There is no such thing as "horsepower take over". Horsepower is merely measure of torque at high rpms. It is extrapolated from torque relative to rpm. That is it. That is the old muscle car thinking that only low end torque matters.
The M4 engine completely gasses out after 6500 rpm. That is the simple fact. That is because BMW opted to minimize turbo lag by fitting very small turbos that great gobs of torque down low, but run out of breath as the rpm climb up.
It is about the area under the entire curve. Not just a small segment.
The mathematical equation is:
HP = torque x rpm / 5252
Torque is what turns the wheel. HP is completely meaningless. Torque curve all across the rev range matters. Not just low end.
FYI, racing engines spend billions of dollars in R&D to make the engine produce as close to peak torque all across their rev range. They are not all foolish companies. I can give you explicit examples, if you need further clarification.
If a car makes 500 HP and 400 ft-lbs and another car makes 400 HP and 400 ft-lbs of torque.
That means the engine making 500 HP produces far more torque at high rpms (and hence higher horsepower extrapolation). The 400 HP engine makes the same/more torque at low rpms, but loses steam at higher rpms.
The M4 engine completely gasses out after 6500 rpm. That is the simple fact. That is because BMW opted to minimize turbo lag by fitting very small turbos that great gobs of torque down low, but run out of breath as the rpm climb up.
It is about the area under the entire curve. Not just a small segment.
The mathematical equation is:
HP = torque x rpm / 5252
Torque is what turns the wheel. HP is completely meaningless. Torque curve all across the rev range matters. Not just low end.
FYI, racing engines spend billions of dollars in R&D to make the engine produce as close to peak torque all across their rev range. They are not all foolish companies. I can give you explicit examples, if you need further clarification.
If a car makes 500 HP and 400 ft-lbs and another car makes 400 HP and 400 ft-lbs of torque.
That means the engine making 500 HP produces far more torque at high rpms (and hence higher horsepower extrapolation). The 400 HP engine makes the same/more torque at low rpms, but loses steam at higher rpms.
12-11-14, 06:49 PM
#22
Lexus Test Driver
If I ignore the fact that Porsche GT3 is PDK and Corvette Z06 is manual, this would be the objective explanation
Have you looked at a torque curve of a Porsche GT3? Being a high strung engine, it makes majority of its torque high up in the rpm band. From 6000 - 8400 rpm is where things really start happening. It does not make much torque until it hits high rpm.
Now, on to how that car is very quick, it is called torque multiplication. Gearing multiplies torque. That is a constant. When you have majority of your torque available to you at high rpm and you add torque multiplication through gears, you get a very quick car.
Wheel torque at specific rpm = crank torque at rpm x (final drive ratio ) x (gear ratio)
So the more torque available at high rpms, the more gears multiply it = the faster you are.
In the case of Porsche GT3, it gets peak horsepower at 8250 rpm of 475 HP. I can easily extrapolate how much torque it is making by solving for torque and it is exactly 302 ft-lbs@8250 rpm.
So even at redline, the Porsche GT3 makes a whopping 93% of its peak torque and hence the horsepower. If instead of 475 HP@8250 rpm, it were making 350 HP@8250 HP, that would merely mean instead of 93% of its peak torque, it is only making 68% of its peak torque at 8250 rpm (or 222 ft-lbs@8250 rpm). When I mentioned M4, it was already plummeting hard after 6000 rpm.
That goes back to my point of the more torque available at high rpm, the more it can be multiplied in lower gears with higher than 1:1 ratio.
Last edited by 05RollaXRS; 12-11-14 at 07:16 PM.
12-11-14, 08:18 PM
#23
Lexus Test Driver
Always catching me bro LMAO! I guess i forgot to quote the person's post saying "only if it weighed 600 lbs less"
But I know that JoeZ Intake and Exhaust Combo will change the power measured at the wheels
Can't wait for that
But I know that JoeZ Intake and Exhaust Combo will change the power measured at the wheels
Can't wait for that
12-13-14, 05:13 PM
#25
Lexus Champion
12-13-14, 05:19 PM
#26
Lexus Champion
Thread Starter
Oh...and obviously the lack of cats
12-14-14, 06:48 AM
#28
Lexus Champion
True if the stock RCF dynos similar to a modded ISF with headers and exhaust. I would think the ISF would be faster on the straight away due to less weight. I am not to sure about the track even if the ISF has a Torsen LSD. Just my opinion I could be wrong "Dennis Miller". Any Thoughts...
Last edited by LexISguy; 12-14-14 at 07:19 AM.
12-14-14, 01:11 PM
#30
Lexus Fanatic
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Join Date: Nov 2004
Location: Under an IS F since 2008
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They are still areas of improvement for the oem RC F exhaust..
The ONE flat spot on the IS F is now replaced by two flat pipes on the RC F..
More to come...
Joe Z