How much hp do you think my 305 tbi auto trans will put to the rear wheels? I thinking well below 150 hp. I watched a mustang (89 5.0) put 190 hp to the wheels today. I thought I was going to see a little more than that maybe 215. I have a friend with a RX-7 That put 410 to the wheels. The thing pulls 10.6 in the 1/4. I'm going to dyno my car just to see. Its free so why not. Cars mostly stock excepted exhaust which isn't worth anything but a cuple horses.

 

Depending on the mileage, state of tune, I think you're about right.
Check out the TBI board for info on how to pad that # a bit.

 

The January 2003 anniversary isue of Hot Rod Magazine has a neat formula to figure rear wheel H.P.. All you need is an accurate 1/4 mile mph number.

The formula is this

hp= (mph divided by 234)3 x weight.

mph divided by 234, that number cubed times weight.

My basically stock 305 tpi figures out around 165hp at rear wheels.

H R says the formula is pretty accurate for cars from 9 - 16 sec 1/4 miles and under 4000 lbs. They gave it an accuracy rating of 4.5 out of 5.

Have fun with it

 

Thanks, I'll remember that. 165hp at the wheels sounds about right for a 305 tpi.

 

That's odd, since the factory stated it at 190, IIRC.

 

TBI motors were 170 HP rated, IIRC; I'd expect to see something in the 135-140 RW HP range for a bone-stock one.

For comparison, a stock 305 TPI usually puts about 165 HP to the wheels, out of its rated 205-210 crank HP.

At "dyno day" here locally a few months ago, a bunch of the Mustang owners looked kind of glum when my 305, with its stock Q-Jet carb and intake and all emissions devices installed and operating in California emissions trim, put 208 HP to the wheels.... poor guys, I just hated it for 'em

 

The way i've been figuring out *approxiamte* RWHP is just the flywheel HP minus 25 percent (or FWHP x 0.75)

its usually fairly close (within 10hp), but rarely bang-on

 

Reading the whole article in H.R. that formula is good within a percent or two. If you've got a weight slip and a time slip you've got your rear wheel h.p

 

I run a "dyno day" twice a year for the members in Ontario, and one of the guys has a 1988 Camaro with the 305 TBI. He rebuilt his motor and blueprinted it, and he managed 155 RWHP. My little LG4 with a couple of mods only managed a weak 151 RWHP. Since then I have added headers and a dynomax cat back. Also planned is a cam swap. The "peanut cam" is the weakest part of the 305. In order to make any HP, a new cam is in order. Good luck at your dyno session, just don't be too disappointed if the numbers aren't what you hoped for. I see it all the time, guys thinking that their mods are going to create huge amounts of HP, only to find a minimal gain. I, myself, included. It cost money to create any real HP.