Converter size differences?

['72customdeluxe]

I know stock is 12" for a th350. I'm looking at an Acc 2800-3200 stall converter for a future heads/cam combo. Will the weight loss from a 9.5" converter (how much less do they weigh?) make a noticible difference in how quickly the enigne revs? I know the motor will get into it's power quicker because of the slip, but like in free revving or out of the stall range, is there a big difference in the smaller lighter converter?

[Schralper]

think of it as either letting the clutch out easy OE converter, or dumping the clutch @ 2800 w/ aftermarket.
It won't effect you engines ability to rev, thats engine compression.
what's "free revving"? you mean in revving in park? come on, seriously?

[Marv D]

The smaller converters are not to save weight, I think yur missing the whole point of the 11" vs 9" . Large diameter, lots of fluid is not efficient as a high stall configuration.

ACC,, is that Art Carr convertors your looking at?

Do some research before you dump down the cash is all I'll say.

['72customdeluxe]

Jesus, chill out on the free revving thing. Yes I know, the higher the converter stall the smaller you go because of the pitch and all. When out of the stall range of the converter, would the lighter weight of a smaller converter make a noticible difference in the way it revs out, like a lightened flywheel would on a manual car? And no, I don't care how it revs in park, I was trying to basically find if the difference in rotating mass is noticible. You're missing what i'm trying to say. I also fully understand how a converter works with the slipping and all. I'm basically asking, 9.5" vs. say a restalled or stock 12". Will the lighter weight be noticible when OUT of the converter's stall range, say at 5000 or so rpm. I know the smaller one is more efficent and what I would want, but will I be able to notice the lessened rotating mass, just wondering for ****s and giggles. I WOULD get the 9.5 anyways, not the cheaper 12.

[Super73]

Any time you change roatating weight, there will be some form of change in ET/MPH. For instance, if you had two flywheels the same weight but one was 15" in diameter vs 19" in diameter. The 15" would go through the RPMs a bit faster due to spining weight on a larger diameter. Simple physics tells us that moving or stoping an object of same mass but larger diameter is harder to do.

How much will it chang you ET? I could not beging to tell you. There are so many minor vriables.

['72customdeluxe]

Yup lots o' variables to racing. Now I just need gears, tires and a real motor I'm thinking if I ever plan to bring this sucker around with me (college or such) I need to go with a mild/stock 4.8/5.3 and a 3200 or below converter. Still want 4.10's and absolutely need a tru-trac. Even my 180 horsepower monster will light that one tire fire now All in time and money

[Super73]

4.8 or 5.3?? Gen 3 motor?

If that is what you are refering to, you mine as well buy a iron 6.0 as you can find them just as cheap (with in a couple hundred).

Also, if you do that, would you run a 4l60E or 80E? If so, you can go BIG on the verter and retain a lock up. That will keep the heat down and drivability up.

['72customdeluxe]

yeah a gen 3. I know it's pointless to pick the smaller motor over a 6.0, excpet in oneway, the mileage. If I did it in the near future, it would go infront of my th350 with a big cooler, converter, and a shift kit. In the future, built 2004r with lockup. They have ls1 throttle body t.v. cable set ups and that would be cheaper to put bigger power too than a built 4l60. It would retain the mechanical speedometer too. I'm thinking with the all aluminum 5.3 and no emissions plus tri-y's and duals etc. could get me 22mpg... If a 5500 pound modern crew cab can do it, why can't I?

[Super73]

But.... And this is a big but... If you are going to try and get performance out of the 4.8 or 5.3, your gas mileage is going to suffer a greater percentage than a 6.0. Soon as you put a cam in the 4.8 or 5.3 the volentric efficiancy and TQ down low changes dramatically.

Lets put this on the table, my wifes AWD Trailblazer SS would get 15.5mpg on a long freeway trip when we first got it. With nothing other than a K&N Filter, E-fans and some tuning, it now knocks down 18.8 on a long flat freeway cruise at 75mph with the factory 4.10's.

['72customdeluxe]

But, I figure bolt ons and a tune with a stock 5.3 would get me into the 13's. But, there is never enough power and a stock 6.0 is even faster. I don't know what i'm doing at this point. Hopefully going to the body shop today! I need a limited slip, lowering and some 555's before I worry about the motor. As great as the Vortec heads and all are, the only way to go that makes sense these days is a gen 3

[Super73]

What are you planing for intake?
What is your target weight?
What headers are you planing on running?

I think a bolt on 5.3 will make about 300-315 to the wheels with the right combo through an auto. I honestly don't think it will be enough to get you there unless you put steep gears in the rear and put the right verter in. When I say steep I mean 4.30's with 28" tall tire. Also most likely something closer to a 4k stall. But with that tire/gear, you would only be at 2,200 rpm at 65mph with the converter locked.

Now it it were me, I'd put a 220/224 cam in it with a 4,500 rpm converter and 4.56's with a 28" tall tire and and try to go 12.9x.. With that cam, you not going to loose bottom end TQ, it should have no problem keeping vacum at idle and run very well.