What car would you rather race?

[Andy Bettencourt]

I know this may not be perfect but try and just answer "Car #1", "Car #2" or "EVEN". The cars are obvious but I want to gauge opinions without naming names. I am getting a ton of feedback from drivers of car #2 that it is now dead as a choice. I want to see what drivers of ALL cars think. Any answer is accepted if you believe in it. Not intended to be a debate.

Car #1:

2680lbs
220 crank hp
130ft/lbs torque to the wheels
Gear ratios 1st to 5th: ®280 Disc

Car #1 has an aero advantage and a center of gravity advantage that is tough to put numbers on, but is there. Front and rear strut type suspension.

Car #1 has 125ft/lbs+ from 5000 to 7000rpm. 130ft/lbs from 6000 to 6500RPM (100ft/lbs at 3000, 115ft/lbs at 4000, 125ft/lbs at 5000rpm)

Both cars are RWD. 170lb weight difference.

Car #2 has 160ft/lbs+ from 2500rpm to 6100RPM. Over 170ft/lbs to the wheels from 4000RPM to 6000RPM. Over 180ft/lbs from 4700 to 5500RPM. Strut type front as well.



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[lateapex911]

Car 1:
Hp: =
TQ: vv
Trans: v
Brakes: ^

Car 2:

HP: =
TQ: ^^
Trans: ^
Brakes v

With the torque deficit car 1 has, the ratios are even more important. brakes are a draw, except for the weight, so a slight advantage to car 1 there..

All in all, too close to call.

[Ed Funk]

Andy,

I&#39;d choose to race car 2. on paper it looks like the brakes would be up to the extra weight, and the torque and transmission are much better, especially for NE type tracks.

[MMiskoe]

I think I&#39;d take #2, provided I can mess w/ diff ratios.

6% weight penalty, 30% torque gain. Brake size is minimally different, but the sizes are pretty big in comparison to other cars in that weight range. Might be a problem for long enduros but for sprint races I think you&#39;ll find pads that can take it.

Now do tell what you&#39;re getting at!

Matt

[64oeg]

Tough call, but on paper it&#39;ld be #2. Now of course if I happened to be much more mechanicly familiar with car #1 compared to car #2, that might sway my thought process.

So, are we ever going to hear what&#39;s up?

George

[Eagle7]

I love my #1. It&#39;s a blast to drive and cheaper to maintain. Got that distinct sound, too.

[lateapex911]

hey hey, lets not ID the cars, just the specs...

[Hracer]

Since these are mystery cars, a critical factor has not been established that, given the weight range of these cars and everything else equal, easily tilts the favor one way or the other. So which wheels are putting the power down on both cars? Assuming both are fwd, then definitely the lighter #1. If both are rwd, based solely on those specs alone they seem pretty even imo, but out of personal preference I&#39;d probably take the heavier car #2 with more tq.

[Doc Bro]

Alex brings up great points.
Also, to make a decision on cars this close I would also factor in costs for upkeep and maintenance. If one were an oddball (ala Z3) then I&#39;d go with the more readily available car. The comparison is so close though it&#39;s splitting hairs.....looks like a great race on paper!!

R

[zracre]

Car 2...torque will win. take car one, take away some aero, give it smaller brakes, change the weight distribution and make it FWD...then what do you have? oh and take away 5 ft lbs of torque

[R2 Racing]

take car one, take away some aero, give it smaller brakes, change the weight distribution and make it FWD...then what do you have? oh and take away 5 ft lbs of torque
[/b]
It would be a GSR! Don&#39;t forget to also add 10lbs to it. ;)


I think I&#39;d probably take car #2. The torque and the gearing overcome the added weight, IMHO. Everything else seems to be too close to sway one way or the other.

[944-spec#94]

Hmm,
I like ligher cars. That is car 1.

Torque is a bit weak however.

I would like to look at the power curves however.

Seems like car 1 is rather peaky. Car 2 probably less so.

The impact of the gear is coupled with shape of the power curve. The peakier the motor the more important the gearing.

Hmm 200 lbs vs 40 ft-bls of torque?

I&#39;d probalby need to start looking at suspesion types and chassis stiffness.

I have to admit that 200 lbs is very temping and possible a better qualfing car. The heavier car may be a better race car as you are less impacted by traffic with more torque.

[Andy Bettencourt]

Edited for more specific info - torque curves and peak torque correction.

AB

[kthomas]

By the time you diff ratio up the torque to the rear wheels for car 1 it&#39;s close enough. I&#39;ll take car 1 less the 200 lbs.

Which car do I already have parts for? :)

[Bill Miller]

The bigger brakes should be up to the extra weight (although, I&#39;m not sure what impact it has on tire wear). I&#39;d take the pool table of a torque curve and the nice gearing. Car # 2 please, in blue!

[944-spec#94]

Given the torque curve of car #2. I think racing car #2 would net you more wins. In traffic that torque edge will allow you to pass.

Car #1 needs to keeps its momenutm going to be fast. Get held up and you get passed.


That said I am thinking that if you want to set an all out lap record in clear track conditions (no traffic or obstructions) and can swap final drive ratios to fine the one "perfect" for a track... Car #1.

If you are shooting for one perfect lap then I think car 1 has the edge due to less weight and better aero. However since racing is rearly about absolute speed and often more about dealing with being off line, defending postion, taking position, working traffic and dealing with uncertainties... I think car #2 wins out.

Car #1 may set track records, but car #2 will win races. :P

Truthfully however I think the driver will determine more who wins and loses in Car #1 vs Car #2 fights.

[tlyttle43]

Either a few data points have been left out or the numbers don&#39;t make much sense. Asuming the HP peaks are roughly the same, the cars shouldn&#39;t have that much difference in the torque for the same crank HP. Either Car #1 continues to make torque MUCH higher up the RPM range, or it has some hideous drive train losses to get that much difference in the torque numbers. (Or someone is playing games and running the two cars in different gears.) Based on the hints about what the real cars are, I assume it&#39;s a difference in the RPM for peak HP.

Based on that, I&#39;d rate the two cars about even. Even HP, Car #1 weighs a little less and Car#2 has slightly better ratios and aero.

The torque numbers are misleading - they both have pretty flat torque curves (in the ranges shown - I&#39;d like to see what car #1 has at 8000 rpm). And despite the old line about torque winning races, HP IS what counts. The other old line that rarely gets repeated "You can multiply torque, you can&#39;t multiply HP".

Tom Lyttle

[Andy Bettencourt]

More info:

- Torque at 8000rpm for car #1 is 110ft/lbs.
- The reason the numbers don&#39;t add up is because car #2 is restricted on the top end. Peak COULD be around 240hp unrestricted.

Other numbers added to first post.

[64oeg]

Even with the edited numbers, I&#39;d still choose car 2. With the caveat that if I were more familiar with over the other, I&#39;d choose that one. I still don&#39;t have a clue as to what either car is.

George

[Jiveslug]

Tough call on that one. Im partial the the driving dynamics of the higher torque car, but Im also going to be keeping an eye on the wear and tear on the cars as well... Hmm... I would choose #2. The power delivery seems more to my liking and would seem to lend itself to being more fliexible and forgiving.

[Bill Miller]

Either a few data points have been left out or the numbers don&#39;t make much sense. Asuming the HP peaks are roughly the same, the cars shouldn&#39;t have that much difference in the torque for the same crank HP. Either Car #1 continues to make torque MUCH higher up the RPM range, or it has some hideous drive train losses to get that much difference in the torque numbers. (Or someone is playing games and running the two cars in different gears.) Based on the hints about what the real cars are, I assume it&#39;s a difference in the RPM for peak HP.

Based on that, I&#39;d rate the two cars about even. Even HP, Car #1 weighs a little less and Car#2 has slightly better ratios and aero.

The torque numbers are misleading - they both have pretty flat torque curves (in the ranges shown - I&#39;d like to see what car #1 has at 8000 rpm). And despite the old line about torque winning races, HP IS what counts. The other old line that rarely gets repeated "You can multiply torque, you can&#39;t multiply HP".

Tom Lyttle
[/b]

The flaw in your logic is that you&#39;re assuming that the two engines are of the same type.

[lateapex911]

Is it true then, that Otto 4 cycle, 2 cycle, and Miller engines all have different torque/hp characteristics?

I always thought that basically, HP was work produced, and was mathmatically based upon the tq numbers .

[Eagle7]

The torque numbers are misleading - they both have pretty flat torque curves (in the ranges shown - I&#39;d like to see what car #1 has at 8000 rpm). And despite the old line about torque winning races, HP IS what counts. The other old line that rarely gets repeated "You can multiply torque, you can&#39;t multiply HP".[/b]
Agreed, but it&#39;s the area under the HP curve between the shift points that&#39;s important. And if the areas were close to the same, the flatter curve would be much preferred over one that&#39;s quite peaky.

[charrbq]

#2...horsepower this close is only a number...wt is a problem, but torque is the key...gears are almost no big deal in this case

[its66]

Either a few data points have been left out or the numbers don&#39;t make much sense. Asuming the HP peaks are roughly the same, the cars shouldn&#39;t have that much difference in the torque for the same crank HP. Either Car #1 continues to make torque MUCH higher up the RPM range, or it has some hideous drive train losses to get that much difference in the torque numbers. (Or someone is playing games and running the two cars in different gears.) Based on the hints about what the real cars are, I assume it&#39;s a difference in the RPM for peak HP.

Based on that, I&#39;d rate the two cars about even. Even HP, Car #1 weighs a little less and Car#2 has slightly better ratios and aero.

The torque numbers are misleading - they both have pretty flat torque curves (in the ranges shown - I&#39;d like to see what car #1 has at 8000 rpm). And despite the old line about torque winning races, HP IS what counts. The other old line that rarely gets repeated "You can multiply torque, you can&#39;t multiply HP".

Tom Lyttle
[/b]


The basic numbers actually do make sense. The crank HP on car #1 might be slightly high vs the whp/torque estimations. Torque is a measurement of force. Horsepower is a measurement of work. It is a function of torque and RPM. If an engine&#39;s torque curve is centered around a low RPM range (such as a semi-trucks diesel engine), you will have an engine which produces a relatively low HP when compared to torque. IF the engine&#39;s torque curve is skewed toward the upper end of the rev range, that engine will have a relatively high HP when compared to its torque rating(such as VTEC Honda&#39;s and certain engines with trianglular looking thingy&#39;s inside). I would estimate that Car # 1 probably has 115 lb-ft at 8000 rpm. With the numbers given, car #1&#39;s torque peak would be at approximately 6250 rpm. Car #2&#39;s torque peak would be at approximately 5100 rpm.

If you know either torque or HP at any given RPM, you can calculate the other. HP/RPM=TORQUE/5252.

[MMiskoe]

Andy - any chance of spilling what it was you were fishing for here & what the cars were?

Just curious.

[steve s]

i am guessing that car 1 would have to use a 5.1 final drive and that is a lot less losses through the driveline
car 2 would probably use a 3.7 final drive which is harder to turn so you lose more through the driveline.
car 2 with the heavy weight will not be great on a heavy braking tracks as homestead or sebring club course. also harder on tires.but then the question was which car 1 or 2 assuming both car well prepped and money was no object just winning i&#39;ll chose car 1.
p.s. remember car 2 will have the SIR to limit his hp.so he cannot make any more power . car1 on the other hand can do some more R & D and find some hidden hp somewhere in the engine.
what was the hp level of car1 2years ago ???????compared to what it makes now.??????and some engine builder are still finding more. :dead_horse:

[its66]

I&#39;m not so sure that the gear ratio of the differential has a measureable difference in drag(loss) through the drivetrain. Isn&#39;t the parasitic loss defined more by the design of the diff itself(bearing design, teeth shape and angle, preload, etc) I know that a Ford 9 inch rear has more loss than a chevrolet 12 bolt rear does with the same ratio. The higher (numerically) gearing does aid in multiplying torque which makes it easier for the engine to get the car rolling/accelerating.

BTW...5.12 with .757 5th gear equals 3.87(car 1)..pretty close to a 3.7 overall(car 2). The spread through gears 1-4 is a little further apart. Differential gear ratio is free. You can run any ratio you wish, so that really shouldn&#39;t even be a factor. Each racer has to make the decision which diff gear is best for his/her application. You can chose gearing for more torque multiplication at the expense of top speed, or you can gear for top end at the expense of acceleration. trade offs suck. :)

[steve s]

.757 5th gear is not the choise 5th gear is on car 1. there is a closer gear available.also youre right the diff multiply torque so then you&#39;re almost equal to car 2 torque wise with the 5.12 ???? then why would you run more weight in car 2 ???
at the wheel in theory car 1&2 has just about the same torque and hp ##
off the topic jim are you going to sebring this month&#39;s end hope to see you there.
carlos and myself is will to accept any penalty or adjustment scca deems necessary to level the playing field, just give us some time to do some R&D. that all we ask. :dead_horse: let it die and wait for some results.from scca

[seckerich]

.757 5th gear is not the choise 5th gear is on car 1. there is a closer gear available.also youre right the diff multiply torque so then you&#39;re almost equal to car 2 torque wise with the 5.12 ???? then why would you run more weight in car 2 ???
at the wheel in theory car 1&2 has just about the same torque and hp ##
off the topic jim are you going to sebring this month&#39;s end hope to see you there.
carlos and myself is will to accept any penalty or adjustment scca deems necessary to level the playing field, just give us some time to do some R&D. that all we ask. :dead_horse: let it die and wait for some results.from scca
[/b]
It is the only LEGAL option--anything you wish to share with us?

[steve s]

oops my mistake . i&#39;ll never build anything illegal. when i build car1. :wacko:
and i still think car 1 is the car to build unrestricted engine is the key choice here.

[its66]

Actually, the torque multiplication is almost identical between the two cars in top gear. 3.87 vs. 3.7 is a 4% difference. Overly simplified, if you use car #2&#39;s 180 lb-ft as the standard, that effectively gives car #1 135 lb-ft. A gain of 5 lb-ft of torque. Hardly equal. If you work the same math in each gear, car #1&#39;s apparent disadvantage is lessened somewhat. Fifth gear is where the difference is most disproportionate. If car #2 uses a shorter gear to gain even more of a torque advantage, it&#39;s top speed suffers. --

I&#39;ll not only be at Sebring, I&#39;ll bring an extra 6 pack for you. Come on over. You can even bring Carlos, I&#39;ll share with him too.

FWIW, I agree that the lead time on the SIR was too short. I would think 90 day minimum, maybe longer.