Best gear for 9.90

[Lenny5160]

Originally Posted by Charlie Yannetti

While it is true that finish line RPM plays a part, I was convinced a few years back by Eddie Jr, at Select Performance, to go to a 4.56 gear.. not only to enhance his converter set-up, but that I would be surprised by the charge coming off the stop.. I now have 2% to 3% slip in the converter at the top end, and that charge coming off the stop is awesome, and I go out the back door at approximately 7600 RPM with my 565.. I am only 2150 pounds also..

While I was a nay-sayer, until I switched from the 4.30, I doubt I'll go back.. while it slightly increased the RPM, I didn't seem to affect the MPH at all...

Are you saying that the car comes off the stop much harder, your converter got more efficient, but you didn't gain any MPH?

Was there a measurable gain anywhere? Could you stay on the stop longer?

[Charlie Yannetti]

Originally Posted by Lenny5160

Are you saying that the car comes off the stop much harder, your converter got more efficient, but you didn't gain any MPH?

Was there a measurable gain anywhere? Could you stay on the stop longer?

Although I didn't mention MPH, I'm up between one and two.. also, I usually do stuff to try and take time out of the box.. not put more time in.. and I really don't like carrying 3.00 in the box either...

[Shake & Bake]

rob7181,
Going from the 4.10 your running to say a 4.33 would only be a 5% increase, but going to a 4.56 is going to be a 9% overall increase in performance. Plus you should pick up around 3mph.

[Tom Goldman]

Like Charlie ,I run Select converters . I went to 4.56 gears from 4.29 in my Vette which weighs in at 2400# .
I picked up 2 mph with an increase of 250 trap rpm .
converter efficiency went from 10% slip to 5-6%. AND very importantly , the converter temperature dropped way down when coming off the stop.
Since Charlie's car is a '27 Roadster, one of the hardest cars to get MPH out of I'm not surprised by the lack of improvement in speed.
I would defiantly recommend 4.56 gears in your car.
Racers get too hung up on trap rpm's , if your engine is still pulling at the stripe ,let it eat !

[Keith 944]

^^^^^^this

[Dano]

Originally Posted by Tom Goldman

Like Charlie ,I run Select converters . I went to 4.56 gears from 4.29 in my Vette which weighs in at 2400# .
I picked up 2 mph with an increase of 250 trap rpm .
converter efficiency went from 10% slip to 5-6%. AND very importantly , the converter temperature dropped way down when coming off the stop.
Since Charlie's car is a '27 Roadster, one of the hardest cars to get MPH out of I'm not surprised by the lack of improvement in speed.
I would defiantly recommend 4.56 gears in your car.
Racers get too hung up on trap rpm's , if your engine is still pulling at the stripe ,let it eat !

Did the cars reaction improve?

[Charlie Yannetti]

In my combination, the gear change didn't seem to affect my reaction time.. I didn't change any numbers in the box..

[Dano]

Originally Posted by Charlie Yannetti

In my combination, the gear change didn't seem to affect my reaction time.. I didn't change any numbers in the box..

No improvement on my cars reaction either with a 4.10 to 4.57 change.