Competition Question about gear ratios and drag racing.

[fishjack1]

Quick question for you drag racing gurus - Does the 0-60 or 1/4 mile performance vary running different rear end ratios?

4. 10 vs. 3. XX etc. ? Is there and advantage or disadvantage to either?

 

[DRAG DIESEL]

I would like a 3. 08

 

[Forrest Nearing]

they make a 3. 08 gear for the Ford Sterling diff... I believe 3. 31? is as tall as it gets for the D80



Forrest

 

[therabbittree]

i've got 3. 07's hehe... . but i've got a older 1 ton srw dana 70 ... . i hope the truck runs awesome with my new p pump and twins im working on hehe... thanks deo

 

[StakeMan]

4. 10's don't help when it comes to the 1/4 mile. At least with 24v because of the rpm limit.

 

[Forrest Nearing]

deep gears are for vehicles that make their power at high RPM... we're dealing with torque monsters here... taller the better for the most part.



Forrest

 

[fishjack1]

Thanks for the replies - I figured that the taller gears would be a better choice - unfortunately I'm stuck with the 4. 10s.



JACK

 

[StakeMan]

Then your best bet is to plan your bombing for high rpm.

 

[fishjack1]

Stakeman,



What are a couple of ways to "plan your bombing for high rpm".



My truck runs great from about 60-100 mph 2000-3200rpm - pretty high EGTs doing it. I'm trying to decide on my next bomb - maybe a Piers HX-40? any other suggestions? delivery valves? etc.



Thanks,

JACK

 

[bmoeller]

I would think a Piers or DD cam and/or a bigger turbo would help it breath better at higher RPMs to bring down your EGTs. I think the cam would be the first choice of the two. After the EGTs come down to a good point, then more fuel. If you add more fuel now (delivery valves), it would make the EGT problem worse. Need more air first. With higher RPMs, there is less time for enough air to get in. With a cam with either more lift and/or duration, it should allow for more air in the same amount of time.



JMHO. Someone please correct me if I am wrong.

 

[BillGotthelf]

therabbittree-where did you get 3. 07's for the Dana 70? I have been looking all around and no one makes any thing taller than the 3. 55's I have already.

fishjack1-You can try taller tires also. I ran 28" taller drag slicks with a top speed of 108-switched to 30" and put trap speed to 115. I have talked with M&H about a 33x14. 5x16LT DOT approved drag slick-should be available in May.

 

[fishjack1]

BillGotthelf,



I am running 285/75 R16s (about 33") tires to make up for my high reving 4. 10s. That has helped.



bmoeller,



I am leaning to-wards the Piers HX-40 turbo for my next bomb for the simplicity of the install. I never considered a new cam. That sounds like quite an undertaking - what other mods are required to install a cam? New valve springs etc. ??



Thanks all for the suggestions - Please keep em' coming have some $$$ burning a hole in my pocket.

 

[therabbittree]

the 3. 07 gears come stock in the firstgens that had the 727 auto 3spped no overdrive transmission i believe 89, 90,91. 5 you could get these trannys and these gears. . problem is the carrier and haxle housing supposedly different then a 4. 10 carrier so to use them you'd have to swap to the older axle etc... i run 285,75,16. 5s now and i can hit about 90 plus mph at 2100-2300 on my autometer tach. . i messed with the max rpm screw but u haven't touched the govenor spring yet . . this is in the ve pump. . i have a p pump on the work bench that i am plaqnning to swap in during the spring. . 4000 rpm and 285's and 3. 07 gears should get up and go..... i hope . . i got a set of enterprise laser cut d valves, 370 injectors, and a hx55 i want to use a bigg turbo for a twin setup. . i already swapped in a second gen intercooler etc. . so i hope she will get up and fly. . i i do all this stuff soon i'll be needing a detroit locker and transmission bee / torque convertor swap etc...

later

Deo

\x/ hillolk!