Quote:
Originally Posted by Fully Vetted
So, I just got my car back from Corey who installed 3.90's and I kind of see what you're talking about. I expected this hair on fire experience of having trouble keeping the front wheels on the ground and that's not what happened. However, after a week of driving it and breaking them in now I absolutely love them. It almost felt like the car was slower at first because I was carrying more speed into the 2nd and 3rd shift points and it was noticeable. I got there quicker but I wasn't going as fast. The real beauty of these things though is hitting 3rd gear. That, too me, is where you make up anything you feel you may have lost because this thing hauls the mail now in 3rd and 4th gear. The RPM's are staying right in the meat of the curve and it never ever lets up.
I'm wondering if your impression has changed any now that you've had it a month or so? Mine certainly did.
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Dittos...
I too find the performance trade-offs interesting, as the advantages between the stock 3.45 vs. 4.10s goes back and forth, depending on what the immediate application is:
Ami's 91 ZR-1 "Turq Monster" with 4.10s has approx 5% more hp than my 3.45 "Phoenix" and the combination of rear gear and brute hp tops my car in the quarter, every time. From the seat of the pants, it is a thrill to drive on the street and on country roads. However, in longer contests, the differences are less obvious.
Case in point:
Bob Banks' ZR-1 and my motors are pretty close, power wise: both @ or near the 510 chp range. However, Bob has 4.10s and I have the stock 3.45s in the rear.
One example does not a trend make, but we ran side-by-side at the last 1/2 mile WANNAGOFAST event last June. What I observed I think might be pertinent to this discussion (my reason for sharing it):
We started from a soft dig: more or less even. However, by the 1/2 way point (quarter mile), Bob had 3 to 3-1/2 lengths on me. I suspect Bob was still in 4th at that point, and had to shift into 5th as I was just shifting into 4th. That is when the gap began to close, and was whittled down to 1-1/2 to 2 lengths at the finish.
In the end, Bob (4.10 gear) crossed the 1/2 mile trap at 138+ mph in 5th and the "Phoenix" with the 3.45s crossed at 144+mph, & still in 4th.
However, in spite of gaining on him, he still beat me to the 1/2 mile finish! That initial lead afforded by the 4.10s was too much to overcome, in spite of a significant speed advantage the Phoenix had - at least at the 1/2 mile point.
So, I dunno... Now having opportunity to experience both ratios; 4.10s vs. 3.45s, the each have their place. I like the snap Ami's car has when passing on the highway - and the extra 20-30(?) ponies at the wheels is just the cherry on top. But, I also like that long hard pull my car has to 90ish mph in 2nd gear, following a 5-2 downshift from about 45-50 mph. The 3.45 ratio delivers more torque to the rear wheels (above 75 mph) than the 4.10s do in 3rd, in spite of the 5% hp advantage, and without the additional shift too boot.
So, depending on what or where one likes performance to kick in, moving to a 4.10 ratio might not be "the bee's knees". Having both to compare back and forth makes the distinction much clearer now, and I've cooled to the notion of 4.10s just a little, now that I have that and the 3.45 ratio to compare it with. Maybe 3.73s or 3.90s? And, (to the OP) so it goes....
Paul.