Quote:
|
Originally Posted by HIZNHRZ
I'm also not sure I'm following your cpmparison to a L98.
|
Sorry. I'm not sure what exactly I draw as a conclusion from it either. But, gears are chosen for a reason. Part of it is what fits in the tranny/diff. But mainly, you have a set of gears, 6 in this case. And you want to balance performance with economy with drivability.
In the case of the LT5 vs L98, you have one engine with a very limited rpm range, vs one with a very wide range and which is substantially stronger up top.
So partly what I mean is that in terms of drivability and having to shift, going with 4.10:1's is no worse than the amount an L98 owner must shift with stock gears. Except that you are making one hell of a lot more power and will have one hell of a lot more torque at the wheels due to the higher torque of the LT5 plus the mechanical advantage of 4.10:1 vs 3.33:1 rear gears.
So that is a positive thing to be said for the 4.10's I think. The amount of shifting can't be that bad, as a base Corvette shifted that often from the factory. Plus it gets you into the meat of the powerband quicker.
Now cruising rpm will of course be higher than an L98, and fuel economy will suffer.
It would almost be like having an L98 that has had it's power output doubled and its sound improved.
On the flip side, the stock gears. They show off the engines wide flexible power band better. I mean, you can about hit 60mph in 1st gear. In a 6-speed transmission, that is insane. 4-speeds didn't have gears that tall.
Fuel economy is great, driveability is great, and the engine is flexible enough to work with the tall gears. Plus you don't have to shift much, and it is harder to blow the tires away in 1st and 2nd.
I haven't looked at the numbers, but I believe this is the kind of gearing cars like the Countach had. Tall gears so it could run fast. And a big motor that could pull it off. To me the 3.45 gears are sort of exotic. They let you savor the engine as it pulls through the rev range.
I asked Mark about 3.73's at BG. He mentioned the 4.10's are probably good for a .5 second improvement in the 1/4, and that you give back .2-.3 seconds for the extra shift. 3.73's will also require an extra shift, but will not have the same gain. So the net effect may be a wash in the 1/4. 3.90's, I don't know.
As to my gut, well I think now it is telling me, stick with the stock gears. While the 1/4 mile improvement would be nice, I don't really drag race the car that much, and I mainly just do it to have fun and to go fast. I probably won't trap any faster because of the gears, so who cares. I do love how long the cars legs are on the street. I do still think 3.73's would be cool, but it's just a very small change for the same amount of cost. So I probably never will do it.
And in the back of my head, I don't want to give up any top end. Sure, the car will probably never see 150mph, let alone 180. But still, it's nice to know it can do it. 5th gear @ 7300rpm with 4.10's would be good for about 175mph. 3.90's put it at 185mph. 3.73's top out at 195. And the stock gearing, if the motor could pull it, would run to almost 210mph @ 7300 rpm (about 200mph at 7000rpm). On a ported car, 3.73's would probably enable the highest top speed just because the power peaks around 7,000 (or at least my car does).
So to me, 3.45:1 or 4.10:1 makes sense depending on whether you like the sort of gentlemanly exotic aspect, or the tire burning 1/4 mile monster aspect. 3.73's and 3.90's fall somewhere in-between. So maybe the answer depends on where you fall between those ends? Hope that's helpful and not just rambling.
P.S. an upshot of 4.10:1 gears is if you want to do some 3rd gear pulls for datalogging, you only have to hit 97mph on Great Seneca instead of 115mph!
P.P.S to answer the question asked, if it were my car, the cost were the same, and I had a choice of 3.90's vs 4.10's, I would go 3.90:1.