ALS/500 ZR-1

[Serial]

Time                   Track
81.352 (1:21.352)      Road Atlanta

For this month's ALS Challenge, I have built out 3 different variants of the C3 ZR-1.  My results:

            ZR-1C        ZR-1P        ZR-1P2
P.I.         A848           A849          A848
Speed         6.1            6.1           6.1
Accel         6.0            6.1           6.2
Braking       5.5            5.5           5.5
Handling      5.2            5.2           5.2
Power         499            500           499
Torque        434            502           467
Weight       3,168          3,168         3,168
0 to 60      4.298          4.207         4.079
0 to 100     9.470          9.269         9.410
Top Speed    183.6          183.4         184.7
60 to 0      111.5          109.9         108.6
100 to 0     295.2          293.7         294.2
G's @ 60      1.09           1.09          1.09
G's @ 100     1.06           1.06          1.06
Times       81.807         81.909        81.352



ZR-1C (Centrifugal Supercharger)
Race Intake
Race Exhaust
Race Ignition
Race Fuel
Race Cams/Valves
Race Engine Block
Street Intercooler
Sport Centrifugal Supercharger
Full Platform/Handling
Street Weight Reduction
Widest AVON Slicks
15" Volk TE37 Rims
Forza Race Rear Wing

ZR-1P (Positive Displacement S/C With Stock Cams)
Race Intake
Race Exhaust
Race Engine Block
Race Intercooler
Race Positive Displacement Supercharger
Full Platform/Handling
Street Weight Reduction
Widest AVON Slicks
15" Volk TE37 Rims
Forza Race Rear Wing

ZR-1P2 (Positive Displacement S/C With Race Cams)
Race Intake
Race Exhaust
Sport Fuel
Race Cams/Valves
Race Engine Block
Race Intercooler
Street Positive Displacement Supercharger
Full Platform/Handling
Street Weight Reduction
Widest AVON Slicks
15" Volk TE37 Rims
Forza Race Rear Wing


Both builds feel very similar at Road Atlanta.  The biggest difference comes in the form of Cams.  The ZR-1C has the Cam upgrade which allows it to use the gears much differently...not necessarily better, but different.

I put in a good amount of laps with both cars.  Both have minor tunes (very close to stock numbers), and default aero.  It seems as though ZR-1P should have a clear advantage, but that doesn't seem to be the case.  I'll make sure to keep up to date on future developments.

Do the TORQUE numbers make a significant difference (in Forza) ?

[Fit4aking]

I think so.  Last night I was re-building my Tuscan S in A-class and was debating which power upgrade to buy.  I was down to the ignition or the fuel upgrade but couldn't decide.  But WHY??  Well the ignition and the fuel resulted in the same hp value but there was one more ft/lb of torque in the fuel (iirc).  The one ft/lb also netted an additional PI point.  Based on that I believe that torque plays a part in the PI system but it may just get lost in translation when it is applied to the car model.  If not why else would a GNX be so fast with such low HP and such a high TQ curve.

Interesting observation, I'll have to pay more attention to it when I build out the Vette's.

[JG4tr]

I believe that the torque numbers do matter but, whether they matter with a particular engine in a particular car on a particular track should depend on a few things. Primarily engine powerbands, Gear ratios and gear selection on track.

The powerbands: Different engine configurations are going to make power of two types , HP and Tq,  at different rpms. Let's say that you have an engine with a horsepower band in the 6-8000rpm range and a peak torque occurs from 3-5000rpm. Having more torque on hand is only and advantage if you are setup to use it through your gear ratios and on-track gear selection.

The gear ratios: If you set up your transmission with close ratio gears so that when you upshift at 8000, the rpm drops to 6000 in the next higher gear, then it isn't really going to matter that you have gobs of torque from 3-5000rpm.

Gear selection: The way for you to benefit from extra torque, is for you to use those rpms in the peak torque range. This could be done either with a lengthening of the individual gears or just by downshifting one fewer gear to allow the engine to drop into the lower rpm range for corners and utilizing the extra grunt to pull you out... 

J

[Serial]

New ZR-1P2 build added to 1st post.

J - you are dead on, and I agree completely.  HAVING more Torque is one thing...USING more Torque is another.

Now, this hp/tq discussion got me thinking...well, the ZR-1C was definitely lacking in TQ, but seemed to run better lap times.  What did it have that ZR-1P didn't ?  The answer is a set of Race Cams and Valves.

So, I went out and put a set of Race Cams on ZR-1P...the new car is called ZR-1P2.  It nearly splits the difference in the torque in the 2 old builds down the middle.  This is my new favorite build.  I spent some time with it tonight putting down some pretty good laps.  It was consistent in the 81's, and seemed to be the best overall build.  With a few tweaks, I was able to take it down to a low 81.  There is still more time to be had for sure.

My new question is - how in the hell is the Acceleration rated calculated by FM2 ?

[Hekalite]

The speed, accel, braking and handling ratings are not recalculated based on setup so they are only good as a quick guide.  If you have a default gear selection that is not right for your current motor, it will throw those numbers off.  The benchmarks are a little better, but 0-100mph is not enough information.  If they added a 0-top speed calculation it would be so much better.