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I have a quick question you might have seen my other posts but my 87 camaro has ran a best of 12.10 at 113 with 2.73 gears with a th400 trans 26" tires. i only use 2 gears through the 1/4 mile i shift into second at 6700rpm and and cross the line at 6800 rpm in second gear. i had just put a set of 4.10's in it put a 3 gallon cell up front and got some control arm relocation brackets. my question is since i went with the 4.10's i heard my trap rpm will only be like 6100rpm in 3rd will this cause me to run slower time since im not turing a higher rpm like before or will it be about the same. Im hoping to hit around 11.70 . also taking front bumper support off and of course the stock gas tank think i will be able to do it.

why no replies to this ?? . you will def be quicker with the new gears regardless of trap speed rpm`s .. probably even more so than you think ..especially if you get some grip and drop that 60 foot time a bunch

Originally Posted by steve88crx

I have a quick question you might have seen my other posts but my 87 camaro has ran a best of 12.10 at 113 with 2.73 gears with a th400 trans 26" tires. i only use 2 gears through the 1/4 mile i shift into second at 6700rpm and and cross the line at 6800 rpm in second gear. i had just put a set of 4.10's in it put a 3 gallon cell up front and got some control arm relocation brackets. my question is since i went with the 4.10's i heard my trap rpm will only be like 6100rpm in 3rd will this cause me to run slower time since im not turing a higher rpm like before or will it be about the same. Im hoping to hit around 11.70 . also taking front bumper support off and of course the stock gas tank think i will be able to do it.

What I can't figure out is why any one would try to build a "drag-car" with a 2.73 gear.
I am guessing this is a sbc.
To run a 12.10 pass with a 2.73 that is doing very well and would require a very hard-core engine.
In fact I would love to see some specs. on this engine combo.
To add to this back in aug. he was running 13.75's with a 2.15 60 ft. time.
On Nov. 1 he says he is now running 12.10's at 113 mph along with 1.77 60 ft. times.
Pick a story.

when i ran the 13.75 it had 1 broken pushrod and i did not notice till i got home i was going to adjust the valves and i seen it. i had to get new locks beacuse they kept backing off.

350 bored .30 over dart iron eagle 215cc platinum heads with 64 cc chambers , isky 507/507 lift 247/247.50 lift with 108 lsa, victor jr intake ,holley 650dp choke horn milled, 1.5 roller rockers, hyper flat top pistons with 4 valve relief, eagle crank, 1 5/8 longtube headers turbo 400 trans with b@m shift kit red neck 4000 stall..... in the first pass you can hear me shift into second right as i pass the camera the second and third runs i found out later but there was a plug wire on the header and it was breaking up.

YouTube - camaro1

Nice vid, cool sound!

Originally Posted by steve88crx

when i ran the 13.75 it had 1 broken pushrod and i did not notice till i got home i was going to adjust the valves and i seen it. i had to get new locks beacuse they kept backing off.

350 bored .30 over dart iron eagle 215cc platinum heads with 64 cc chambers , isky 507/507 lift 247/247.50 lift with 108 lsa, victor jr intake ,holley 650dp choke horn milled, 1.5 roller rockers, hyper flat top pistons with 4 valve relief, eagle crank, 1 5/8 longtube headers turbo 400 trans with b@m shift kit red neck 4000 stall..... in the first pass you can hear me shift into second right as i pass the camera the second and third runs i found out later but there was a plug wire on the header and it was breaking up.

YouTube - camaro1

Like I said why would you ever build a drag car with a 2.73 gear??

Originally Posted by erik erikson

Like I said why would you ever build a drag car with a 2.73 gear??

Like a Powerglide with overdrive

Steve,

all else being equal i.e. same trap speed you won't be turning as high but you will get there a lot quicker and will probably pick up some mph so maybe you hit the traps closer to 6500. Let's not forget about converter slip... Good chance you'll trap near the same rpm's

If you're at 12.10 today I would expect something in the 11.7's maybe even 11.68. For your mph of 113, the car should be at 11.9's already and I would expect you'll pick up quite a bit more with the gear.

With the shorter gear, traction becomes more important so if you had any trouble hooking before it will be harder now.

Most of this is pure speculative bench racing with a few slightly educated guesses. Run it and tell us how it turns out!

-Chris

I got a 2.73 in a streetrod and I don't particularly like it, sure wouldn't want it a drag car.

if i knew that i had a 2.73 in it before i built the motor i definatly would have changed the gears but the guy who had it before me said he had put 3.73 in well i kinda knew he lied the first time i went down the track.

Originally Posted by steve88crx

if i knew that i had a 2.73 in it before i built the motor i definatly would have changed the gears but the guy who had it before me said he had put 3.73 in well i kinda knew he lied the first time i went down the track.

Now all you need is a powerglide ,so you can do 70 mph in first gear......

For TH 400 with a 1.48:1 second gear and 26" tires, at 6800 rpm you are at 130 mph. With a 1.57 second gear you are at 122 mph. Something is slipping or the tires is a spinning. The gears will help tire spin if that's it.

Kitz

thanks for clearing up the trans gear ratio... I was figuring something like 1.7 from the calculations but didn't know typical 2nd gear ratios in th400. If you figure about 10% converter slip, it works out close to your 1.57 ratio...

-Chris

Originally Posted by erik erikson

Like I said why would you ever build a drag car with a 2.73 gear??

you might run a 2.73 because it is your street car that you race now and then,he switched to 4.10 so his new problem will be traction or if he hooks broken drivetrain parts,never ending circleif the stock 7.5 rear is in that 87 camero it will break soon

ya i hope i get a couple passes in it. i have a 9iinch sitting in the garage im getting it together little by little hope i can get it in by next year along with ladder bars.

dana 60