Joe_G

I sure don't have the education to argue with you , but if you look at my graphs above you see that at any given roll race speed my geared car has 20-30 rwhp over the non geared car due to the increased rpm at any given speed.

Unless you are roll racing past 130 or so (redline in 4th) seems to me gears are better for roll racing too? Am I missing something?

glass slipper

Let's just say for "discussions sake", we have the exact same cars with the exact same engines making the HP shown in your graph above with a 6800 RPM rev limit and on stock size tires. The exception is you have the MZ6/4.10s and I have the MN6/3.42s. We're going to do a roll race from 65-155 MPH for no good reason other than the fact that I already know the end results (spoiler: you lose this time). (Highlight to see the spoiler.)
At 65 MPH, you're in 3rd already because you're going too fast to be in 2nd while I'm able to use 2nd...let's see where that puts us. You're at ~4700 RPM where you're making ~340 RWHP while I'm at ~4950 RPM where I'm making 370 RWHP. I maintain this advantage for a long 24 MPH through 2nd until I shift at ~89 MPH to 3rd where the RPMs fall back to ~4960 and ~370 RWHP. You continue in 3rd gear until you have to shift to 4th at ~92.5 MPH where you fall back to ~4750 RPM and ~350 RWHP. For the brief 3.5 MPH you were in 3rd at the same time I was in 3rd, you were making ~430-435 RWHP while I was back at ~370-380 RWHP. After your shift to 4th at 92.5 MPH, I'm at ~5150 RPM and ~380 RWHP where I again enjoy a 30 RWHP advantage until I have to shift at ~122 MPH to 4th where I fall back to ~5230 RPM and ~390 RWHP. You continue in 4th until you have to shift to 5th at ~132.5 MPH where you fall back to ~4830 RPM and ~360 RWHP. For the 10.5 MPH where we were both in 4th, you were making ~430-435 RWHP while I was making ~390-410 RWHP. My 4th gear goes to ~158 MPH so from 132.5 MPH to 155 MPH, I'm making ~410-435 RWHP while you're making ~360-410 RWHP. In column form, we have:

MPH................you're RWHP........my RWHP
65-89................340-435............370-435
89-92.5..............430-435...........370-380
92.5-122............350-430............380-435
122-132.5...........430-435...........390-410
132.5-155...........360-410...........410-435

I think it's obvious to the most casual observer that I jumped out in front at the beginning, put down more average HP from 65-155 MPH, and won by several car lengths. Two things conspired against you...1) your wide ratio transmission (5th gear killed you) and 2) I got to pick the terms of the "race".

If you were to pick the terms, your best bet is a ¼ mile run from a dead stop where your 4.10 gears multiply the same torque better than 3.42 gears to jump me off the line and get you up on top of your HP curve way before me. Combine that with the fact you get into 4th gear to put more average HP to the ground and you win very easily.

If I were going to optimize roll racing with the 3.42 gears, I'd have a ZR1 gearbox with even closer ratios (1st-4th is 2.29:1-1:1) to keep your engine closer to the HP peak since the HP peak occurs so close to the rev limit. The ZR1 power curve looks similar to yours which is why they went with a close ratio gearbox...the RPMs fall too far off the power curve after each shift with a wide ratio gearbox like the MZ6.

What you're missing is the fact that gears are for multiplying torque but there are also transmission gears as well as rear end gears. Once you get out of 1st gear, the 4.10 gear doesn't do anything for you. The MZ6 with 4.10 gears give you an overall ratio in 1st through 5th of 12.18, 8.49, 5.86, 4.10, and 2.91 while the MN6 with 3.42 gears give you an overall ratio in 1st through 5th of 9.1, 6.09, 4.45, 3.42, and 2.57. Compare the overall ratio in 3rd-5th of the MZ6 with the 2nd-4th of the MN6...the MN6/3.42 has higher overall ratios in each gear so all I had to do was catch you right after a shift and I'll be ahead of you on the HP curve. You did the same thing essentially on the graph with the exception that you were dyno racing while I was real world racing. That is unless you could talk me into racing you 4th gear to 4th gear...and that would be highly unlikely unless you wanted to go to 140 MPH.

The other piece of the puzzle you're missing is HP can not be multiplied. If the engine is putting out 400 HP at that instant in time, then you're going to get 400 HP (minus drivetrain losses) to the rear wheels no matter what gear you're in.

Joe_G

I was pretty sure you'd give us all the final explanation for this if I asked for it! Thanks Slipper.

I do, indeed, choose to always race from a "dig" (and on the drag strip I might add). So I've always chosen gears in my Vettes.

For those that like to put a little science to these things, there is a great website Craig Leres put together that lets you fool around with gearing, tire size, redline, etc. for various transmission types.

http://xse.com/leres/ss/calculator.html


Here's where I think in the real world I'd have you in the example you gave. I think MOST folks would not start a Vette in 2nd at 55 mph as they'd think it would be too low a gear. I'm no roll race expert but I think most start in 3rd gear at highway speeds. If we started in 3rd on the freeway at 55, I'd be at 4053 rpm and you'd be at 3073 as shown on the charts linked below. I'd jump ahead and stay there, and you'd be seeing my hazards when it's time for me to shift to 5th at 130.

If you're too smart for that, then I'd say ok, let's start at 80. You would have to start in 3rd and I'd still be able to do so. Above 80 mph start and you'd win but I don't think rolls start that high.

Me:
http://xse.com/leres/bin/gearratio?t...rofile=&wheel=

You:
http://xse.com/leres/bin/gearratio?t...rofile=&wheel=

I think the moral to the story is the winner would be the guy who gets to choose the race assuming they are educated on their car and its shift points well, which I think many people don't know well, so I think advantage goes to me with 4:10 gears. This Forum and particularly you, Glassslipper, always help in the education regard.

LEAVINU

I'm with glassslipper....... and could have never taken the time to break it all down as he did but from my experiences he is right.

Let's not forget the standing mile as well here. My 3.42 500rwhp C6 will easily chase down and pass (launch adv to the 4.10 gear ) a geared 500rwhp C6 as it looses steam up top. JoeG mentions a 185mph top speed but that was not in a mile if I remember correctly.

I'll be at the next mile event in Miami if anyone with a gear is in attendance we can compare apples to apples.

LEAVINU

To the guys starting in 3rd from 55mph......

You're right Joe you'd walk all over them in that situation. I definitely start in 2nd from anything 70 or below. I've even hit 2nd as high as 75mph...... ....... talk about getting slammed back in the seat.

Don't underestimate 3rd in a 3.42 car at 80mph, thats a pretty nice sweet spot there as well and it will only keep pulling from there.

If I was primarily a drag racer I'd definitely gear my car but I do all other types of driving as well so the stock gear works perfect for me.

Joe_G

Yea the 185 was a little past the line, I ran it up to my 6700 redline before shutting down. I think I ran a little less than 170 in the mile but thats a function of HP. I dare say I'd run slower with 3:42's as my gears give me more HP at a given mph and we all have to shift to 5th in the mile run.

My buddy who runs right with me in the drag strip has a c5z and his short 5th means he has to shift to 6th in the mile run which kills his acceleration. I handily beat him in the mile, the c6 has a better 5th for top speeds. I recall an ad with a stock c6 at 189 and the z at 198. No c5 can reach that stock.

My car is actually geared optimally for what I do mostly which is drag race. I'm at redline in 4th gear at the stripe on a cool day which is using all the HP the car has.

robz

Those are the kind of details that us 1/4 mile 'hobbyists' use to eek out every .01 from our cars.

SgtRod

That was brilliant! It seemed that gearing threads always had believers sticking up for their choice rather than aproach it scientificly. Its true that you should build your car for its inteded purpose. Point in case is that most geared people always use 0-xxx to win the debate. Also with 900+hp, it's hard not to dominate the mile This thread has my vote for being one the most informative.

When is the next mile run in Miami?

Joe,

Thanks for the invite, I apreciate your kindness. I have heard from another local guy that you are the local trackstar! I will PM you later.

LS1LT1

5knives

Lots of great info from both sides, and discussed civilly too, who would have thought?

Build the car for the race not the race for the car.

LEAVINU

Keep tabs on www.milemarker-1.com for details. Hope to see you there.

StoplightWarrior

This turned out to be a very informative thread, and we should be thankful. I think we should all give Hungry Hippo some colored marbles to eat rapidly.

SpinMonster

When the terms of the race are to end at a speed that doesnt coincide with the non-4.10 geared car's redline, it isnt going to end at its peak HP and the 4.10 geared car's avarage HP is thus higher. My car is a Z51 with 4.10's and hits about 130 at redline in 4th. The stock geared car at this speed is much lower in RPM due to its 153 max in 4th.

Picking the right range IE 50-130 favors the 4.10 geared car for a great power range in 2nd gear all the way to 130 ending in 4th at redline. The stock geared car is too low in rpm for a 2nd gear start and too high for 1st so the jump goes to the 4.10 car. At the end of the 130mph, the 4.10 car is at redline and the stock geared car is at 4500rpm.

Picking 60-150 favors the stock geared car.
Picking 50-130 favors the 4.10 car.

Picking a top speed race by far favors the geared car because no car will hit 200mph in 5th gear. 6th with 4.10's puts it right near redline. The crazies in NY do this. Although its not in the cards for our discussion, roll-ons are inherently dangerous to non-participating drivers and I didnt build my car to do them.

In jest: In practice see my car move so fast that I need to send a post card to let the other guy know where I am.

SpinMonster

I spoke at length with Subfloor last night.

His 0-60 is 2.3 seconds.
His 0-106mph (1/8 mile) is 6.505 seconds.
His 0-139 was 9.95
His HP is about 600rwhp and likely 550rwtq.
He has 3.42 gears (Z06 diff) which on an A6 is the same as a base car with 5.10 gears in first....you read that right, 5.10 gears. I dont see anyone looking at his results thinking gears are hurting him.

If you are a roll-on race guy, you will not need them but then there are lots of 650rwhp cars running high 11's.

Gears are the best thing you can do for low end performance and that includes the E-force S/C.

I got off the phone for the second time thinking what a kewl guy he is and how thought out his car is. I cant help but think how a progressive dry shot would put him in the mid 9's.

Craigster05

To moderators and any else interested - this run was NOT on a public road - it was filmed at a legally sponsored event on an airport runway at the Dade Collier Airport at the standing mile event - please do not lock or block the above post.

Joe_G

Good point Craig! I need to start saying that when I post it. I get a kick out of posting as it means I get to re-live the event! That was a ton of fun.

Craigster05

Hopefully, I will be able to join you next time we need to talk, buddy!

Joe_G

Awesome! Call anytime buddy.

Ragtop 99

I agree, plus half of them that do try bang the rev limiter because the car if it hooks jumps pretty hard if its hooks and most of the other half break loose the wheels and get off the throttle to rehook.

You're mixing the wide ratios of the MZ6 and the effect of gears. That exaggerates the effect that you are trying to show. 92.5 - 122 mph drops much lower on the geared car because of the tranny ratios, not because the rear gears caused all that drop.

Roll racing may be a contest of where to optimize your start and end speed, but gears give me the opportunity to run through peak power more often than a non-geared car. I don't have a sign on my car saying I'll race you, but only if we agree to start at 75 mph and end at 130 mph.

It may not work in every situation, but over time the ability to go through 4 gears by 130 mph improves the odds in any given race of passing through peak HP more often then going through 4 gears in 160 mph. At least it does for me as I don't find many safe places to go over 140 mph.

robz

I agree that gears are not hurting 1/4 mile performance and mph and I prefer as much gearing as possible for my vette in 1/4 runs.

I also agree that it is crucial to match the setup with the proper gear on the drag strip.

The one thing I would say to Chris is that if he is not in the 1.3x 60' foot range for whatever reason then he is leaving some et on the table.
My H/C C5 ran similar numbers to subfloor above with 4.10 gears.

I also agree with the fact that there are many 600rwhp vettes running high 11's but IMO they just shouldn't be.