Gearing for 4-link suspension

[racertrash]

I would appreciate a little help understanding gearing and RPM change on a UMP modified.

We run a 4-link (clamped up) suspension on the LR, and spring-on-top Z-link on the RR.

We are running a 6.39 gear in a quick change rear end on a 5/16 medium-banked oval (those who are around West Central Indiana probably know where the only 5/16 oval is). At times, we turn as high as 8500RPM.

I was told that going up in gear (6.56) would actually LOWER the RPM.

Is this due to the taller gear getting up on the bar and driving the tire to the ground, putting more load on the engine?

Thanks in advance.

[charcoal01]

If you are good with throttle control, yes. You'll use less brake on entry, don't have to slide the tires as much and getting the car into the ground harder. The more hooked up you are, the less rpm's the motor will be able to turn.

[powerslide]

what degree heads are you running? Do you Ti valves? 8500 is zinging. Highly unlikely at that point that going up in gear will lower the RPMs.

Can you tell if the drvr is spinning the tires? Some drivers are gonna hit the chip wether you give them a 5.13 or a 7.13 they are going to the floor no matter the conditions, they dont understand when its slick if you have a good motor you arent getting much more than 1/2-3/4 throttle. These types of drvrs run better w/ little motors in the slick.

[racertrash]

Engine has 23 degree heads and roller valvetrain. Verified that the chip is set at 8700. Also spoke with the driver about whether or not he feels that the tires are spinning and not grabbing. he feels that the tires are not spinning, and when the track dries out, he is only using about half throttle.

I appreciate everyone's input. Thanks.

[Renegade Cust Susp]

we usually start night with a 6.29 then if the track is right around the bottom we will go up to a 6.39 or higher.

[racertrash]

Going to try a 6.57 this weekend and see what the driver thinks.

Thanks for your input

[racertrash]

Well, the 6.57 did not work in out favor on a heavy, then tacky track. 6.39 worked better for us.

[racin6mod]

the 6;57 will work better on a dry slick track,go up in gears as the track slows(dries out) you should have tried 6;20 in the area.

[racertrash]

We actually began running a 6.20, then went to the 6.39 mid-season last year.

I'll certainly keep in mind going to the 6.57 when the track goes black slick. Thanks for the suggestion.