Bowtie Overdrives?

[Trimman]

I'm thinking of gettin the stage two> If it gets me two more mpg it'll pay for itself in about nine months.
I drag about a 2000 lb. trailer for work with what I have now (350 no lockup)
with no problem. Gettin about 9 mpg. 11 mpg without it.
What do ya'll think of Bowtie?

[northern 85]

So far they have been very helpfull to me.I have a tci 700r4 with the bowtie tv system for a demon carb, seems like its idleing @ 70 mph, stuff and she will drop in to 2nd and get!!!

[eagle23]

The only concern I have about what you're suggesting is not BTO, but the 3.08 rear in your profile and OD. With a 700R4 you'd have a 2.15 4th gear (effectively). If in really flat country, it might work, but in hilly Atlanta GA (hi!) I suspect you'll mainly stay in 3rd pulling a 2k trailer, so it may not net you much mpg. It will have a better 1st gear, tho. Without the trailer, maybe the axle/trans combo will work, but tire size will be another factor.

There have been discussions about making sure your main crusing speed is near the torque peak or at least well within the torque output of the engine, or it'll lug and mpg will suffer.

This site may help
http://www.ring-pinion.com/content/calculators/RPM.asp

Brian

[piecesparts]

My son's truck (86 chevy- 350 motor) had a 700R4 tranny that we put into it, after we took out the 350C tranny. The truck ran down the road at about 1900 RPM and the cruise control worked itself to death, because it had a 3.08 rear end. The fuel mileage sucked really bad 11 to 13 MPG, depending on where it was driven at. The rear was changed out for a 12 bolt 3.73 posi unit and the mileage went UP by 2 MPG. Hard to believe, you ask----well let me tell you the motor runs at 2700 RPM at 70 MPH and the acceleration is smooth with no downshifts to get up and down hills (we live in Kansas where there some moderate inclines that WE call hills). If you put something in the back of the truck it pulls the highway easily and if you tye onto a trailer it handles it real well. I also have a 84 GMC truck with a 400 HP 385 stroker (see the avatar) and a 700R4 tranny and the same gear ratio on the axle, I get 15 MPG when I get onto the highway---Can't complain---The Mustangs do when it jumps them on the ighway.

[Tom]

I have a bowtie overdrives stage 2 2004R and a 3.07 rear. Even with 380lbs/ft the engine is working hard at 80mph and 2000rpm. Thats not to say its working too hard, but 3.73's would increase my milage [drove in 3rd one week to test, MPG went up]

As for bowtie overdrives, I would never buy another transmission from them again. The speedo gears went out within 3000miles, one torque convertor lasted 4k, they wouldn't honor my warrenty because I wouldn't modify the shifter to hold it in 1st gear [that was my choice though] and the tech people are hit and miss, somtimes they are nice and somtimes not.

[pedrofixlater]

I have a 70 buick GS 455. I have a turbo 350 in it now because my son drives it so i took out the 200-4r and 3.42 posi and put the turbo 350 and 2.73 back in. That car was getting better gas milage with the 3.42 and the overdrive than it does now. I am going with a 200-4r in my 75 stepper with a 350 medium cam 3.73 rear end. If you want an overdrive I am rebuilding the 200-4r Got a master rebuild kit, 2800 stall torque converter 13 vane pump kit and shift kit all for 300.00. These 200's and 700's are not hard to rebuild the haynes books take you step by step, so far no problems. I am pretty sure that the 700 is less expensive to build than the 200 i have because of availability. I also want it be known I dont build trannies for a living I am almost done building mine. Give it a shot. Remember one thing that the cable on the 200 and 700 is not just a kick down cable they are throttle valve cables that control ALL shifting they must be set correctly or your tranny will burn up. Also put a tranny cooler on it will add years to the life of any tranny. hope this helps.

[apstguy]

I've had nothing but good luck with my BTO Stage II TH700. I love the thing. Best tranny you can buy for the money. Make sure you properly set up the TV cable and the lock-up. They are both crucial. You MUST get an external cooler if you are towing!

[Hemikiller]

Originally Posted by Trimman

I'm thinking of gettin the stage two> If it gets me two more mpg it'll pay for itself in about nine months.
I drag about a 2000 lb. trailer for work with what I have now (350 no lockup)
with no problem. Gettin about 9 mpg. 11 mpg without it.
What do ya'll think of Bowtie?

I'd try a couple other tricks for mor MPG before swapping trannys.

Run a thermal clutch fan. That netted me 2mpg on one of my trucks.
Hook vac advance to a ported vacuum, verify vac advance is good
maybe increase static timing, decrease centrifugal timing to maintain current total timing; should help coming out of the hole
Try leaning out the Edelbrock in cruise mode, see link: http://www.edelbrock.com/automotive/eps_intro.html
reduce acc. pump shot in carb 'til it stumbles on acceleration, then increase 1 step
install a heat stove and fully functional OE type air cleaner assy, carbs meter fuel more efficiently with a consistant air temp at the carb
Install a 190* t-stat
switch to a full synthetic gear oil in the rear axle, full synthetic oil in the motor
increase pressure in tires to max rated psi on sidewall
lose the bug gard if you have one
install an air dam under the front bumper from a later 80's pickup/suburban
practice driving like there's an egg on the accelerator pedal

[Tom]

Originally Posted by Hemikiller

.
Hook vac advance to a ported vacuum, verify vac advance is good

That wouldn't help milage. All it does it make it idle worse. With ported you get less timing at idle, then when the throttle blades open you get the vaccum up to the port and timing is back to normal. With manifold its just always normal. If your engine can't run correct with manifold vaccum, somthing is wrong elsewhere.

[Hemikiller]

Originally Posted by Tom

That wouldn't help milage. All it does it make it idle worse. With ported you get less timing at idle, then when the throttle blades open you get the vaccum up to the port and timing is back to normal. With manifold its just always normal. If your engine can't run correct with manifold vaccum, somthing is wrong elsewhere.

Heh, I knew someone would post the opposing opinion. Ported vs Manifold vacuum for vacuum advance is an ongoing debate, kinda like Ford vs Chevy

The idea behind the ported is you get advance off-idle, and at light cruise, just when the motor really needs it. Full manifold will dimish the advance if you step into the throttle lightly, making you dip into the throttle even more.

As far as making a motor idle worse, I'm drawing a blank here. If I set my timing at 10* BTDC, it idles just fine. As soon as I tip into the throttle, the motor gets 10* or more of advance to help in off-idle throttle response. It's when the vac adv is on manifold and it's pulling in ie: 12* plus that 10* initial that it would have a problem, namely keeping a reasonable idle. Then when I dip into the throttle on this setup, the advance goes away and the motor is doggy.....

Defense exhibit 1: http://chevyhiperformance.com/howto/97438/

[Tom]

LoL yes the ported vs manifold argument will go on forever, Im just giving the knowlage I've gotten first hand. My vortec 350 will surge at idle with ported vaccum, its rock steady with manifold [thats with 12-14* initial with no vaccum hooked up] Also when crusing high speeds [about 80mph and 2000rpm] if I let off the gas I would get a slight poping out the exhaust, with manifold vaccum theres no problems. I will admit though, when I go to emission I dial the initial back and change it to ported vaccum [works like a charm ]