How to get 302 to 250hp?

[englewoodcowboy]

4.88's are pushing it expense wise. Going to that ratio will require a new 3rd member and they are not cheap. Ideally I would like to run 4.88's in my EB but I am not going o spend the money. Doing the crossover from current tires, 3.50 gears to 33" tires, the calcualtion coes out somewhere close to 4.50 if I remember right so I will take my chances. Worse case down the road someone may get a great buy on a 4.56 front R&P and a complete 3rd member as well but hopefully I will be happy with them.... too soon to tell.

 

[is_wiz]

While I can agree to a point. Swapping gears from 3.50 to 4.27 wont gain you any mileage unless you run a OD tranny and we dont know what gears or tranny he's running.

3.50 stock 3 speed tranny
I like the stock, 3 on the tree classic style.
From the sounds of the varying opinions, I don't know what to do gear wise. I do drive it around town and on the highways both pretty regularly. My mileage does suck. But its slightly better after I found the leak where the filler hose connects hahaha. But still sucks. Probably 11mpg on average.
I think I'll address the gear issue later.

 

[broncnaz]

Lots of people have run that combo for many years its fine you dont need to regear. If your engine is built for your needs and gearing then it will be fine. Many times just a little more power in the engine department is all thats needed and you will see a nice improvement. You should be able to pull 15 mpg with a decently built engine and the proper tuning with your current combo.
Now if you were mostly offroad then yes i would probably regear or at very least swap transmissions to get better gearing on the low end.
While regearing does tend to bring the power feel back to what it was when stock you also have to figure that back in the 70's the speed limit was 55 now its 75 and with speed the RPM's go up. regearing to 4.30's will push the RPM's at 75 to over 3000 rpm. A little high for a 302 but not unreasonable. but it wont help mileage one bit.

 

[cesco]

4.88 gear and 33" tire

4.88 gear and 40" tire... I didn't change tires for the dyno tune. It's in an offroad only beater so I have no idea what the MPG would be...

 

[Broncobowsher]

4.88 gear and 40" tire... I didn't change tires for the dyno tune. It's in an offroad only beater so I have no idea what the MPG would be...

That was the normal tire size. All I did for the dyno was turn the OD off and write a new shift scheduel for the trans that held 3rd gear all the time. With manual control of the torque converter I could make runs from idle to 6000 RPM. Get some true curves over the whole powerband without the trans wanting to shift on me or the converter slipping. Did find a few neat things, below 60 MPH unlocking the convertor helped power, above 60 MPH it was more efficient to have it locked (this is at full throttle in 3rd gear).

 

[KennyB]

ok, New (Old Stock) 1993 Cobra GT40 302. Cast Heads, 9:1, Roller Motor, WIndage Tray, Stock Mustang Cam, Performer Manifold, Edelbrock 600 Card, HEI Ignition. My Dyno sheet says: 302HP, and 322 Tq. Problem is, I just bought a Blower, so, we're building another Motor to run the Blower. My GT40 has only made a couple Dyno Runs. Just drop it in, add 12v and fuel. It's for sale for $3800

 

[KennyB]

MPG? It's just a big Air Pump.... the less Restrictive you get Air In, and Air out,... the More Efficient it is. but, ist a 302... so, a Brick Shaped 4500 lbs 4X4 with a 1:1 transmision is going to be maybe 15 MPG? my modular motor in my 02 F-150 with Intake, Exhaust, programmer, and O/D Tranny?... it gets around 16+ MPG... My 03 Mustang GT Convertable got 24 MPG on the Freeway.

 

[cesco]

That was the normal tire size. All I did for the dyno was turn the OD off and write a new shift scheduel for the trans that held 3rd gear all the time. With manual control of the torque converter I could make runs from idle to 6000 RPM. Get some true curves over the whole powerband without the trans wanting to shift on me or the converter slipping. Did find a few neat things, below 60 MPH unlocking the convertor helped power, above 60 MPH it was more efficient to have it locked (this is at full throttle in 3rd gear).

nice.. I would be happy with numbers like that. never thought about the torque converter, but being able to lock/unlock could have some advantages.