Ok here is a photo of my less then theoretical torque curve. What gears should i get for my new 9 bolt carrier.

I am getting a brand new 9 bolt carrier from a shop in california for $450. Gear sets are $150.

What ratio is best for that torque curve?

My prices are at cost if anyone was wondering, i have connections in the automotive world.

 

What size tires? How heavy is the car? Approx what mph do you expect to trap at? How dependable is this DD graph? i.e. what are the major components, and what did you input into DD? What transmission, and what converter if it's an auto?

 

yeah all that might help.

heres the stats on the internals.

-Scat Steel Crank 3.48 stroke
-6.125" rods
-Hyperutectic pistons 4 valve reliefe .030 oversized.
-10.0-1 CR
-Vortec heads, machines for 1.5" springs(isky double), 1.6 roller rockers, 1.94/1.55 valve sizes.
-Edelbrock Performer RPM air gap intake, 670 Holley street avenger
-Edelbrock Performer RPM camshaft

-700r4 Tranny built, with hardened components, wider bands and all.
-2500rpm stall
-Steel Driveshaft(stocker)

Last weigh in was ~3150lbs

DD seems to underestimate my engine, so i dont think that works very well.

My last trap at 12.3 was at 121mph. My tire size is stock, 245/50/16.

 

I wouldn't go there just yet...

Is this the roller RPM cam, or the flat-tappet one? Did you characterize it as "aggressive roller", "street roller", or what?

Was that run you refer to, with this same engine? What RPM was it at? That weight, I assume was with driver?

 

this is the flat tappet cam,

i put in the exact cam charactoristics the cam is.

the run i did before was with this engine, before it wiped 2 cam lobes.

I am pulling the motor and reringing it, replacing the stock rods and pistons, with the longer rods and pistons.

Motor only had maybe 2k miles on it when i noticed the two less then normal lifters.

the weight was with me yes, stopped at a truck stop. I weigh in at 155lbs

 

the old engine did have a different cam and carb, but, they really shouldn't make all the difference.

 

bump

 

bump

 

Just throw 4.88 in there and climb some trees.

 

i figured it out. I already ordered a set of 3.45 gears for my 9bolt, as well as a carrier. total with shipping was only $712. Cant beat that anywhere else.

 

with that i bet your gonna want 3.70's. 3.27's put me thru the traps at about 4000-4100rpms or so. i trap 100mph.

3.45's would be optimal for 4500-4700rpm trap in a 700r4 and tpi power band of shifting at 4800rpms. 3.70's will put you more into a usefull power band of 6000rpms

trapping 121 on that motor is pretty impressive

 

thats why i've always thought that DD underestimated my motor.

with that trap speed i am capable of getting a high 10 second maybe low 11 second run.

My car may be lighter then the weight i was caled with, but not much has happened since then as far as trashing parts i didn't need.

Its werd, becuase the guy that i know, whome ordered them for at cost, said the opposite. a gear with 3.45 would put me into the better power band, i dont know what is right anymore.

So my new rear end, and aluminum driveshaft are on the way.

Traction is my car's biggest downfall i think. The stock tire size kills it. With the new gears i am swapping 16" rims out for 15x10 cragar's and ill be hooking.

 

i would have gone with a much bigger gear and ran taller tires instead

 

Hmmmm i'll call him firth thing in the morning, see if i can change the order now, or am i set in...

 

well 125mph is 6000rpms in 3rd gear with 3.70's on 26inch tall tire.

3.45's, its about 5600rpms at 125mph with 26inch tall tire

you want to pull the traps at your peak hp rpm or about that. depends on your motor, i would think it would pull to 6000rpms and 3.70's would be better choice with 26inch tall tires.

a 28inch tall tire with 3.70's is the same as 3.45's with 26inchers.
at least if 3.70's is too much on 26inchers, you could swap tires instead of gears to get the same effect.

 

definately 3.70s are the way to go and get bigger tires as needed. assuming you're trapping 122 still with this motor

 

i would also recomend the 3.70's.