I would think this gear swap would be more benificial for the entire range of driving in the car. A quafie and 3.5 gears should allow you to LAUNCH the car after a corner apex. You would be able to get into that 4th gear more often and sooner. I believe on a road course you would be significantly faster lap after lap.

Now as far as the 1/4 mile, 1/8 mile etc goes its basically a math equation with a bunch of money thrown at it, which, in this case, 3.5 gears might not be the best solution to the equation.

I find it difficult to believe that the sedan which is heavier and specs slower than the coupe would be faster than the coupe all other things being equal. I.e. it is easier to drive an auto (most sedans) at the drag strip than a manual (all coupes? or at least all I have ever seen ; - ) which could explain some peoples "experience".

 

so what if u just got the technosquare reflash, then the rpm limit would be higher. would that be enuff to finish the quarter without having to shift? but i mean if ur increasing the rev limit then id say add some more aggressive cams on top of that.

 

The sedan weighs about 70lbs less than the coupe and only makes about 5whp less, tranny to tranny. Factor in the typically larger 18" rims most coupes are outfitted with, and it makes sense why the coupes typically post fractionally slower ET/MPHs. Yes, autos are far easier to launch at the track, especially RWD autos.

 

Very true that the 7100rpm limiter would help, but then the issue becomes the powerband. The non-RevUp VQ35s peak at around 6200rpms and power plummets after 6400rpms. Holding on to the gear longer would probably make you slower. Cams would definitely help out things in terms of topend power, BUT you trade a large amount of low rpm power which means the car will be doggish off the line and slower in the 330'. To do it right, you'd need a ~3,500rpm stall TC, 3.5 gear, and cams. That would probably be a decent combo, though the TC and cams will make the car lethargic around town.

 

I would agree. If racing the 1/4 the gears would not make sense. In everyday driving there is little doubt to me your overall performace will improve with the planned gear swap.

 

DaveB is right on in regards to the 1/4 mile aspects. From the factory, the 5AT has ideal gearing utilizing the 3.357 diff with the factory gear ratios and 26.7" tires. You manage to cross with just 2 shifts and not 3 like the 6MT. If the 1/4 is your focus, use the 3.357, and that goes for the 6MT or 5AT. I believe the 6MT should be able to cross right around redline with the 3.357.

The shorter final drive does wonders for torque multiplication, like smaller diameter tires, so you do accelerate more quickly. In the 1/4, depending on the speed of shifts and where you are in the torque curve will make the deciding factor. Raising the redline to 7100 rpm is a tradeoff of lower torque for those extra 500 rpm at a higher torque multiplication factor vs higher torque at a lower multiplication factor. The gearing is wide enough its still seems more effective to take it to 7100 then shift. You would need a substantial torque output drop at 7100 rpm to be stronger in a higher gear at a lower rpm. I wouldn't know for sure without seeing a dyno that hits 7100 rpm without fluttering to make a good estimation though. But what I can tell you is that shifting from 3rd to 4th is akin to a 32% power drop at the wheels (assuming drivetrain losses are consistent and equivalent engine torque output).

If you were to race equivalent G35's, one with the 3.3, one with the 3.9, you would find the 3.9 gears coupe would launch faster with a better 60' assuming no traction issues. However, as the 3.9 G35 had to shift into second, the 3.3 G35 would be able to make up some lost time as its accelerating more powerfully still being in 1st. Once its shifted to 2nd, the 3.9 G35 has the advantage again until it has to shift sooner once again. This would go on back and forth and its a question if the extra time for stronger acceleration the 3.3 coupe has in a lower gear makes up for the extra shift and lower torque multiplication of being in a higher gear on the 3.9.

I'm doing a 3.917, Quaife and ECU reflash in a couple weeks. Still waiting on the Quaife still so we can do the actual work. At that point, I'll be able to compare a couple runs I did pre-swap to post-swap.

I'm not doing the swap to be a 1/4 car, but its a good spot to get accurate measurements at fixed distances and draw some observations. I think the gearing is a good basis to create a very nimble vehicle without having to push 400+ whp. Whether or not its an advantage or disadvantage is really going to be a case by case basis.

 

G35 6 speeds come standard with a 3.53 gear ratio.. If you have a 3.9 gear ratio you are saying I will trap a better quarter mile time then if a person had 3.3 gears but you say if you had 3.5 gears then you will trap worse times then having 3.3 gears.. Here is a thread that showed good results. https://g35driver.com/forums/showthr...=3.5+gear+swap .2 off of a 1/4 time is good to me.