Gears Vs Converter

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RobbAdams

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OK, I have a 66 barracuda with a 75 360 basically stock except for a comp XE 262h cam, and a Wieand 8007 intake with a 670 street avenger carb. The transmission is a 904, I got from a local FABO Member.

I have a 3.91 gearset, as well as a 2200-2800 Boss Hog Converter. What are the Pro's / Cons of going either route for better off the line performance.
 
Whats the choice?

Gear vs. converter?
 
Ooops, just re-read it.

I'm with BJR, both will comploment each other well and get you going well.

The cons are;

Converter, increased gas useage and if used alone with a low numeric gear set, you'll take off like a dog.

The gear set is increased gas useage and limited hi speed useage.

The Pros of them are simply better off the line acceleration and when used together, it'll feel really good.
 
Guess I need to explain better Gears would for instance would be better off the line, but are going to increase fuel consumption, and be really high reving if I drive to a show in another city or something.

Better of the line with a converter, but will require a trans cooler, and will experience increased tranny wear.


Oh apparently you were typing while I was!
 
I have to agree with using both. Remember a 3.91 gear set was a factory option back in the day when speed limits were 70mph plus and the cars ran fine and gas consumption was ok. The converter will definatly help with a hole shot if you have enough tire to get a grip. If not I would just use the gear.
my opinion
 
if you use the converter you need the gear so cruising rpm is high enough to lock up the converter. with a 3.23 gear and this converter you may not rev high enough to lock it and therefore waste gas and fry trans due to excessive slippage heat.
 
damn i love this site, you guys are a bunch of bad asses, i learn at least 1 thing new everyday,
 
Nasty69;

Well, let me step up and say thanks on behalf of the group I hope we pass the test.
 
Rob, I recently had the same choice. I even have the same 360 and same cam.
I fitted a 2,200-2800 stall with 3,91s. The car is much quicker, sits right in the power band. The convertor lugged when used with my previous 3.23s.
That said, highway mileage IS a bear, I don't care what anyone says. Even so, it feels like a muscle car and acts like one!
 
Hey Robb, how's it going by the way. If you go to 3.91 gears you'll be spinning 3000 RPM at 100 KM/HR (60mph) for the boys south of the border. I run the 3.91 and it's great for short hops and around town but long distance requires ear plugs and an unlimited VISA card. Why don't ya go half way with a 3.55 gear and 2500 loose converter and of course tranny cooler.

Terry
 
Ideally in a race only car, you would have the engine dyno'ed and know right where the torque peak is. Select your converter to stall at the torque peak. Then, select your gearing so you are hitting you are just a few hundred rpms past your HP peak in the traps. There's a myraid of calculators out there to help you out. Don't forget to add in converter slippage too.

This is a bit impractical for a street car, but that depends on your tolerance to a true race set up. Some high stall converters are really street friendly till you get on it and are quite dual purpose friendly but they will cost you. Here's one maker http://dynamicconverters.com/ Be 100% sure when you have one made that you are being honest with yourself and the maker when giving them the specs or you'll just be throwing your money away.

The above race suggestions will vary depending cam LCA, heads, etc. Some engine builds will hold their hp 500 rpm past peak and some builds will have a very broad torque curve allowing a bit of leeway. Some builds will be very peaky, like a light switch either on or off. No leeway on these builds when it comes to converter/gear selection.

Just food for thought and feel free to disagree.
 
The best choice is a matched package, regardless of whatever that is. When in doubt, you can run any gear with a stock convertor and not lose any performance. You will sacrifice something by running a higher stall convertor with too high (numerically lower) gear. It may be throttle response, or gas milage, but one way or another you will lose something for what it gains you. So if you think it needs gear, stick the 3.91s in. See where it cruises most at. See how the enigne responds. See how you like it. You can pick a convertor better after you know things like typical cruise rpm and your own driving habits with that lower gearing.
 
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