Performance difference with a518

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PWdart

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Does anyone have real numbers on how much et slowed down after putting a a518 in place of a 727?
 
I do not;
but since you are already on page 9, at this moment,
I just want to ask this;
you know an A518 is just a 727 with an od box added,right? Ima guessing the OD only weighs 20/25 pounds or so.
But I also don't know how much power you can fire into the loc-up convertor.
But
You can run just about any rear gear that you have a mind to, and if you are able to take advantage of that, you may actually pick-up performance.
 
Maybe going from a 904 to an A518. But I don't think you'll see a difference. You can take advantage of the OD and run a lower gear and might actually go faster. Plenty of people can make a custom converter to hold up so that's a non issue.

And no I don't have any real experience. That might be difficult to find.
 
I thought I read somewhere a 518 has more loss because, of course, of the od unit. But aren't they different ratios as well? Don't remember offhand
 
AJ/FormS said:
I do not;
but since you are already on page 9, at this moment,
I just want to ask this;
you know an A518 is just a 727 with an od box added,right? Ima guessing the OD only weighs 20/25 pounds or so.
But I also don't know how much power you can fire into the loc-up convertor.
But
You can run just about any rear gear that you have a mind to, and if you are able to take advantage of that, you may actually pick-up performance.
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I was thinking along the lines of frictional losses because there is more mass to turn with the overdrive unit.. Just like a 904 is faster than the 727 because there’s less mass to turn. But I could be wrong
 
67Dart273 said:
I thought I read somewhere a 518 has more loss because, of course, of the od unit. But aren't they different ratios as well? Don't remember offhand
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same ratios. That’s the Way I am thinking about it. that it’s just more mass to turn.
 
PWdart said:
I was thinking along the lines of frictional losses because there is more mass to turn with the overdrive unit.. Just like a 904 is faster than the 727 because there’s less mass to turn. But I could be wrong
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Splittin hairs.
 
Does it matter ? If your car is a dedicated race car there is no need for the OD.
if its a street car that gets raced occasionally its worth the small performance loss . You might actually pickup speed because you can now run 3.91s or 4.10s instead of 3.21/2.76s
 
The real question might be- are the first and second gear ratios the same?
 
PWdart said:
I was thinking along the lines of frictional losses because there is more mass to turn with the overdrive unit.. Just like a 904 is faster than the 727 because there’s less mass to turn. But I could be wrong
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My one buddy will only run a 3 clutch front drum with 3 regular clutches behind his low 11 second duster. Says it’s over a tenth faster. Less rotating weight. Kim
 
PWdart said:
Hope you’re right
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I'd make the swap and not even think about it. Any loss will be WELL worth the effort. It's not gonna make a slug out of it and it may even pick up some. You won't know until you do it.
 
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mbaird said:
Does it matter ? If your car is a dedicated race car there is no need for the OD.
if its a street car that gets raced occasionally its worth the small performance loss . You might actually pickup speed because you can now run 3.91s or 4.10s instead of 3.21/2.76s
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That’s kind of the direction I’m looking at. I could probably lighten some of the stuff in the transmission and make up any loss there would be if there is any. I’m never going to drive this thing 1500miles in one trip. I always like the lower gears definitely helps the acceleration. Looking for the overdrive to basically calm down a borderline streetcar
 
RustyRatRod said:
I'd make the swap and not even think about it. Any loss will be WALL worth the effort. It's not gonna make a slug out of it and it may even pick up some. You won't know until you do it.
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i’m just about 100% sure I’m going to do it. I’m going to pick some brains at the Mopar weekend coming up and the Mopar nationals. So unless somebody give me a good reason not to I’m going to
 
I have a few buddy’s that put the 518s into trucks snd they are s as lol more than happy they did it. 1 guy races his and runs 12.40s. Kim
 
mbaird said:
Does it matter ? If your car is a dedicated race car there is no need for the OD.
if its a street car that gets raced occasionally its worth the small performance loss . You might actually pickup speed because you can now run 3.91s or 4.10s instead of 3.21/2.76s
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Bingo Yatzzeeee!!!

This is why you do a overdrive trans for a street car.
The 904 variant has a few small advantages that add up with less weight, less internal mass to power and if you have the right model a low first gear set. But that can also bite you in the back side of your traction limited to start with, you’ll have to take the time to readjust everything to get the car to bite.

To me, since I was a kid and seen the first 5 spd manual (A Pontiac TA w/a 5spd manual) and later, the first overdriven automatics, it seemed like a win win right off the bat. Weight being the only draw back is well worth the swap IMO.

Just make sure to find out the exact OD ratio and then multiply it by the gear ratio for the new final drive ratio. I like the close ratio OD units to keep things closer to stock unless getting out of the hole is an issue.

More so car weight issue for myself, nothing else.

I’ll be doing swaps on my street rides soon. Sometimes having only a 1:1 final drive in a 3 spd auto or 3/4spd manual can be limiting for a car.
 
RustyRatRod said:
I'd make the swap and not even think about it. Any loss will be WELL worth the effort. It's not gonna make a slug out of it and it may even pick up some. You won't know until you do it.
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Separate the two. No one is arguing whether the parasitic loss is compensated with increased mpg of OD/lower from cruise. Loss is loss. He asked. Could be 20hp @6000 and only 2hp at 2000.
I think its talked about on mofarts, like 15 yrs or more ago. If it were a major deal it would be often reiterated, but it's small and no one cares.
 
MOPAROFFICIAL said:
Separate the two. No one is arguing whether the parasitic loss is compensated with increased mpg of OD/lower from cruise. Loss is loss. He asked. Could be 20hp @6000 and only 2hp at 2000.
I think its talked about on mofarts, like 15 yrs or more ago. If it were a major deal it would be often reiterated, but it's small and no one cares.
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Exactly my point. It's not worth writin a book about, AJ Jr.
 
on the street you can't get into third anyway , under the speed limit, so if you end up with 3.91s to 4.30s, you'll be smoking the tires with just about any V8, most if not all, the way. Even 4.30s will get you 60=4700@zeroslip, perhaps 5000 on the tach, in Second gear..
 
RustyRatRod said:
Exactly my point. It's not worth writin a book about, AJ Jr.
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Now that's where you trip over yourself...:poke:

..Hello...

My name is Inigo Montoya...you keel my father... prepare to die..:D


Show me one car that runs as fast as a regular 727 , same setup.

Now is when you wish you drank.:confederateflag:
 
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