1st gen drag truck project....

The way I look at it, a lockup is worth whatever your converter is slipping. So if you have a 90% converter and 500hp, a lockup converter should give you about 50hp more.
 
Begle1 said:
What leads you to say that?

Lock-up in the quarter is a relatively new concept, isn't it? There are definitely lots of very fast cars that don't use it. The extra powerband of gassers means that lock-up isn't missed as much, but the extra torque of a Diesel should mean that you could run a tighter converter and still get off the line.
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I believe your reply would lead him to say that.Your reponse pretty much tells us that you obviously haven't spent tons oftime around fast diesels or we would not be having this discussion. Diesel folks have been using lock up switches for years.
 
Timbeaux38 said:
I believe your reply would lead him to say that.Your reponse pretty much tells us that you obviously haven't spent tons oftime around fast diesels or we would not be having this discussion. Diesel folks have been using lock up switches for years.
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"Fast Diesel's" are less than a 15 year old concept as well... Dodge Diesel's first got lock-up in '94, and I think it took a few years for ATS or whoever to come up with a locking torque converter that could hold the power the Diesels could make. Now we finally have lock-up converters, so now people are just looking for shafts that can take the power.
The point being that people have gone plenty fast without lock-up, it is still possible to go plenty fast without lock-up, and it is very arguable whether or not it is worth spending over a thousand dollars to add lock-up. And I suspect that not having lock-up is going to make it a lot harder to break shafts as well.

The tightest converters common are 93%; you could probably get a few more points if you ask DTT, Suncoast or Goerend. It makes sense to say that lock-up on a 93% convert or would put 7% more power to the wheels; would 7% more power lead to a 7% faster time? 5% faster time? A tenth in the quarter sounds like a very conservative amount of time to contribute to lock-up, by any standard.
 
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Begle1 said:
What leads you to say that? QUOTE]

Hope I didn't sound like a smartazz!
...I was pritty fast in a turbo gas car before I went to a diesel truck.
A LOT of the logic learned in those days does not apply, as I quickly discovered!
By virtue of long piston stroke & slow fuel burn rate, the effective operating RPM of a Diesel is Much lower than gassers & our trucks are a lot heavier too, & really have to make use of the aditional torque afforded by that stroke & burn rate. The average Cummins makes most of it's HP & torque in the neighborhood of 2000 RPM. The average auto tranny torque converter will flash to near 3000RPM. 5% might be a good rule in gassers, with a wider RPM range, where 500-1000 RPM is a small percentage of the powerband, but it a lot bigger factor on a low RPM diesel.
I picked up almost half a second going from a good 47RH tranny with a partially slipping stock lock converter, to a great 47RH with a billit tripple disc.
I think if he puts money in the 727 now... (great tranny BTW. It's what the RH is built from) IMHO, It'll be waisted, as he will soon want to upgrade to the RH anyway. & at around 500hp, he could get away without a billit input & go with a single disc converter.
1 ride in a bilit convertered truck w/ a switch is all it takes for most to spend the money.
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if you got a tight converter then you cant build boost with out pushing thought the light

I do agree no lockup converters was used 12 years a go you dont want them on a gas car

andd you only have 3500 rpm to run with compered to a 5000 and lock up makes a huge diffance
 
Begle1 said:
"Fast Diesel's" are less than a 15 year old concept as well... Dodge Diesel's first got lock-up in '94, and I think it took a few years for ATS or whoever to come up with a locking torque converter that could hold the power the Diesels could make.
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Wrong.
Joe Webb did his first converter in 89 for a dodge.

The point being that people have gone plenty fast without lock-up, it is still possible to go plenty fast without lock-up, and it is very arguable whether or not it is worth spending over a thousand dollars to add lock-up.
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A lock up switch coasts less than $5. Anybody that has one will tell you that it in and of itself will not break parts...... the guy flipping the switch might.
Who do you know that is outrunning Stuckey without a lock up switch? You can go plenty fast without it, but you can go faster with it.

ON EDIT:
Matt, Take the switch out of the Silverline truck. It isnt really helping you much. Just found that out in this LOL
 
Cummins Express said:
if you ever get the chance to ride in a truck with lockup you should
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No, don't................. it really is not all that different LOL
 
I do know a dude who picked up about 5mph in the 1/4 with a lockup on a "mystery switch" rather than letting the trans do it....they help for sure, but I think the 727 will still be able to put down some respectable times....
 
No kidding Jason? 7 MPH?
His converter must have been bad..... MPH is a measure of HP and the truck should MPH about the same wether locked or not..... The ET will be different though.
 
Locked converter=more hp at the wheels. We picked up about 30hp on my dually by locking it.....also a lot of the guys who are 60ft'ing pretty good run a pretty loose converter so the truck won't leave as violent and spin, or bounce.
 
I get that, but how were you dynoing in fluid?
 
7mph is very believeable. without the switch many trucks wont lock before the 1000 / 1200' mark.
(you should feel what it's like to lock 50' out in Jeff's truck :eek:)
 
Okay.. I figured there would not be that much of a change Matt, Of course I have never seen a PS truck run without lockup and then with it either.
 
That sweet thing has been a christmas tradition for me for a few years now. She makes me feel flushed LOL
 
Cummins Express said:
if you got a tight converter then you cant build boost with out pushing thought the light

I do agree no lockup converters was used 12 years a go you dont want them on a gas car

andd you only have 3500 rpm to run with compered to a 5000 and lock up makes a huge diffance
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The traditional solution to roll through is a trans brake... I can imagine that a trans brake on a Diesel with 1300 foot pounds and a 30 PSI launch would create some of the most awesome carnage ever seen. Ever seen it even tried?
I assume that you've used some sort of roll control linelock already to no avail?

You agree that a tenth is a very conservative amount of time to contribute to lock-up, right? That's really the issue at hand...

Timbeaux38 said:
Wrong.
Joe Webb did his first converter in 89 for a dodge.

A lock up switch coasts less than $5. Anybody that has one will tell you that it in and of itself will not break parts...... the guy flipping the switch might.
Who do you know that is outrunning Stuckey without a lock up switch? You can go plenty fast without it, but you can go faster with it.

ON EDIT:
Matt, Take the switch out of the Silverline truck. It isnt really helping you much. Just found that out in this LOL
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Do you understand that the truck in question has no lock-up capability, so there is nothing to hook a switch into, and to install a built trans with lock-up would cost over an extra $1000?

Dodge Diesels first got lock up from the factory in 1994. I don't know what Suncoast started with that used lock-up. Built lock-up A518s? I wouldn't think they had much over 400 HP either.

turbomatt1 said:
The average Cummins makes most of it's HP & torque in the neighborhood of 2000 RPM. The average auto tranny torque converter will flash to near 3000RPM. 5% might be a good rule in gassers, with a wider RPM range, where 500-1000 RPM is a small percentage of the powerband, but it a lot bigger factor on a low RPM diesel.
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By "flash to 3000" you mean stalling at 3000? The fact that the Cummins is making power from 1600-2400 RPM is why good converters for the Cummins stall at 1600-1800 RPM. If it stalled at 3000 it wouldn't be able to tow much. My factory convertor stalled at the same RPM my Goerend's does, around 1700-1800 RPM.

The 5% was a time thing. If a truck runs 14 seconds with no lock-up, 14 minus 5% of 14 would be 13.3 seconds with lock-up. I think it sounds about right, but nobody's put forth any data yet to really verify anything.

I stand by that $1000 will better be spent on a turbocharter, injectors or water injection than lock-up.
 
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