Photomania

If a C4 has the same horsepower and is the same in everything else, which is faster in the quarter mile: an axle ratio of 2.59:1 or 3.33:1? What about in 0 mph to 60?

Someone told me the actual numbers represent the number of times the engine is turning in relation to the number of times the wheels are turning. Is that correct?

Of all the C3s, C4s and C5s that I've driven or ridden in, I was most amazed at the difference in a six-speed 1988 and a six-speed LT-4 1996. The 1988 coupe had an axle ratio of 3.07:1 and only 240 hp, while the 1996 coupe had an axle ratio of 3.45:1 and 330 hp. Yet, while test driving the cars and going 0 to 90 mph by flooring the pedal, it felt like the '88 coupe was beating the hell out of the LT-4. I had a passenger and he said the same thing. Maybe it was just my imagination.

etteroc27

It was.

H P Bushrod

The '88 didn't have a 6 speed. It had the 4+3 manual and the L98.

0ski_dwn_it

It all depends on traction and motor specs. Assuming that you can put the power to the road efficiently, more gears will tryically accelerate the car quicker. But its really something that needs to be trials and error tested.

More gear will make you feel that you are accelerating quicker.

I recently went from 4.10 gears to 4.56s and the acceleration difference is UNBELIEVABLE, also since my motor needed more gear to optimize it in the 1.4 mile, I ran about 2.5MPH quicker in the 1.4 and my 60' times dropped down a BUNCH.

GeosFun

The stock TPI engine is all about low end torque and it fizzles out on power at around 4400 rpms. So it works well with the 2.59 because the engine stays in the fatty part of the torque curve longer.

Within the last year I removed my 2.59 gears for a 3.73 and the car actually slowed down slightly (et) in the quarter mile! I now have 3.07's and the car is the fastest and quickest it has ever been. I also have done a lot of engine mods, including SR, 219 cam, and Pete K converter which allows it to make power at higher revs.

Although the 2.59 gear lacks the "WOW!" factor, it is actually a pretty good ratio for its intended operating range. Even if the 3.33 is quicker, I doubt it will be so by much until you start making power in the higher rev ranges. Then its strength to handle increase power starts to come into play at (400+HP)

vader86

Can't answer that kind of question without qualifying statements. It depends on the power made across the band.

L98 and LT1/4 will react differently to gear changes because they have different power bands and peaks.

schrade

3.33:1. Period.

wayne lowry

The LT4 car is typically a full second quicker in the 1/4 mile so much for the good old s.o.t.p. dyno huh The 3.33 gear will get the car down the 1/4 mile quicker L98 or LT1/4. The LTX cars respond better to gear changes than the L98 cars with everything else remaining stock. A 3.73 is great for a LT1 and too much gear for an other wise stock L98.

GeosFun

3.33:1. Period.

Have you tried it in a stock L98? How much quicker?

schrade

No.

I'm guessin' it would be 7/10ths to 1 second quicker, from 15s+ to 14.

vader86

say what?

BigLee

Ditto....

aboatguy

Fuzzy Dice

To answer this question we need to know which C4...we also need to know what you mean by "faster"....assuming by "faster" you mean quicker as in ET, then....

Generally the L98 would be faster with the 2:59's...3:07's is about the tallest gear you'd want in an L98..in an LT1 the opposite is true and you would be faster with the taller gear, the 3:33's...with the LT-1 you can actually go all the way up to 3:73's and see improvement...

As noted above, ET's are all about how effectively you transfer the power you have to the ground...gears won't do a thing for you if you spin off the line..neither will HP...I can't begin to tell you how many opponents I have put on the trailer with twice my HP because they spun out of the hole and couldn't get hookes up until it was too late...

Photomania

Thanks for all the insight and explanations about how peak power bands vary from the L98 and LT4 and the effect of the axle ratios.

But I still have this lingering questions. Does the ratio of 3.33:1 mean the engine is turning 3.33 times for each time the wheels turn?

Also, I remember the 4 + 3 transmission on the '88 coupe. I should have simply said manual transmission.

But please tell me what the 33.1 stands for. Maybe I'm dense in this area. My "Corvette Specs" book says the 1990 axle with a 33.3 ratio has 12 pinion teeth and 40 ring teeth and the ring gear outside diameter is 8.5 inches. The 2.59 axle ratio has 17 pinion teeth, 44 ring teeth and the ring gear's outside diameter is 7.875 inches.

dan0617

[QUOTE=Photomania;1562589439]Thanks for all the insight and explanations about how peak power bands vary from the L98 and LT4 and the effect of the axle ratios.

But I still have this lingering questions. Does the ratio of 3.33:1 mean the engine is turning 3.33 times for each time the wheels turn?

Also, I remember the 4 + 3 transmission on the '88 coupe. I should have simply said manual transmission.

But please tell me what the 33.1 stands for. Maybe I'm dense in this area. My "Corvette Specs" book says the 1990 axle with a 33.3 ratio has 12 pinion teeth and 40 ring teeth and the ring gear outside diameter is 8.5 inches. The 2.59 axle ratio has 17 pinion teeth, 44 ring teeth and the ring gear's outside diameter is 7.875 inches.[/QUOTER]

The ring gear teeth divided by the pinion teeth = ratio. (40/12=3.33) The ring gear diameter is exactly that. It is a Dana 44 rear. The other is a Dana 36. Yes, if the "input shaft" on anything with gears (an automotive rear end in this case) makes 1 full revolution, the output shaft or shafts will make as many revolutions as the gear ratio. (2.59 or 3.33 or whatever the ratio in this case)

schrade

No ya don't.

Any car, bike, boat, sewin' machine, anything, is gonna be faster (quicker off the line) with higher gearing.

That ain't no guess.



YUP.

YUP.

dan0617

Car will pull harder with lower (higher numerically) gear ratio. It's basic leverage. They will be quicker off the line if you have infinite traction. Nobody does have infinite traction. (Ski_down_it is obviously close to infinite traction by watching his videos!!! ) If by quicker you mean 1/8th or 1/4 mile runs, then one does need to know what C4 you have and what mods you have to make a gear suggestion. 4.56's in a L98 and you will NEVER get traction. And if you do, you will run through your powerband so fast that a 2.59 geared car will smoke by you probably before the 1/8th.

0ski_dwn_it

A very basic rule of thumb is you want your car to be crossing the finish line at your maz power RPM.

THe problem is most cars can't plant the power at the launch, which costs much more ET than not having the gears optimized at the finish line. More ET can be gained or lost in the 60' time that will effect your ET, than at the end of the track.

As a result most people undergear their cars to bandaid the traction problem and feel their cars are quicker with less gear. However optimized you want it at the start and at the end of the track. This requires a GOOD working suspension.

schrade

Absolutely correct.

In fact, in the quarter, you'd probably have to pit for re-fuel, with 4.56:1