Torque Converter Upgrade
Thread Starter
Instructor
Joined: Dec 2004
Posts: 175
Likes: 0
From: Athens Alabama
Torque Converter Upgrade
O.K. folks, I am having a Raptor Jr. Transmission (4L60E) built by Performance Automotive And Transmission. I can choose from 3 TCs which is 1700, 2000 and 2500rpm stall.
I have been trying to educate myself with no luck as I am still confused. I have searched/read the threads on this subject and cannot draw any conclusion.
My vette is a 94 LT1 Stock, daily driver.
I dropped the tranny and it has a stock 1397rpm TC on it now.
Can somebody educate me here, so I can order the right TC?
Thanks in advance for any advice.
I have been trying to educate myself with no luck as I am still confused. I have searched/read the threads on this subject and cannot draw any conclusion.
My vette is a 94 LT1 Stock, daily driver.
I dropped the tranny and it has a stock 1397rpm TC on it now.
Can somebody educate me here, so I can order the right TC?
Thanks in advance for any advice.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Well, for example in 1st gear the TC is always unlocked. This means that at the touch of the accelerator the engine will run up to the TC stall RPM before the car starts to go faster.
With a stock TC the stall point is rather low so when you press the accelerator speed increases immediately. With say a 2,500rpm TC the engine would have to spool up to 2,500rpm before you would start to increase speed. The former TC is said to be "tight" while the latter is "loose".
I have a 3,000rpm TC in the IROC and it is too loose for my taste. While the new 2,000rpm TC in the Vette is rather tight so that when I'm rolling on the street and stab the accelerator there is little or no lag before speed increases. Yet I can launch at 1,700rpm from a light so launch is much stronger than with the stocker.
The reason for going with a higher RPM stall on the TC is so that the engine higher into the power band on launch.
For me, the stock 1,500rpm TC was too tight but around 2,000-2,200rpm is just about right.
With a stock TC the stall point is rather low so when you press the accelerator speed increases immediately. With say a 2,500rpm TC the engine would have to spool up to 2,500rpm before you would start to increase speed. The former TC is said to be "tight" while the latter is "loose".
I have a 3,000rpm TC in the IROC and it is too loose for my taste. While the new 2,000rpm TC in the Vette is rather tight so that when I'm rolling on the street and stab the accelerator there is little or no lag before speed increases. Yet I can launch at 1,700rpm from a light so launch is much stronger than with the stocker.
The reason for going with a higher RPM stall on the TC is so that the engine higher into the power band on launch.
For me, the stock 1,500rpm TC was too tight but around 2,000-2,200rpm is just about right.
Team Owner
Joined: Sep 2001
Posts: 62,160
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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With an LT1, I would probably pick the 2500 stall TC.
A 'loose' feeling TC means the higher stall, but it implies the feeling you'll get, which is that the transmission is slipping and not shifting right. Until you get used to it, that is. The TC you currently have in there is what you call 'tight.'
The LT1 makes its power at higher rpm, so getting the higher stall will get the car to rev up to around 2500 before the TC locks, similar to the revving a manual to 2500 before you dump the clutch. At that point, you accelerate as normal. It just makes the car quicker, its not adding any power, only letting you get to your powerband before you take off. This ends up making the car quicker to 60mph and in the 1/4, but it shows up more in the 1/4mi.
A 'loose' feeling TC means the higher stall, but it implies the feeling you'll get, which is that the transmission is slipping and not shifting right. Until you get used to it, that is. The TC you currently have in there is what you call 'tight.'
The LT1 makes its power at higher rpm, so getting the higher stall will get the car to rev up to around 2500 before the TC locks, similar to the revving a manual to 2500 before you dump the clutch. At that point, you accelerate as normal. It just makes the car quicker, its not adding any power, only letting you get to your powerband before you take off. This ends up making the car quicker to 60mph and in the 1/4, but it shows up more in the 1/4mi.
Waka, Waka, Waka!
Joined: Jun 2002
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From: Richmond Virginia
CI 4-6-8 & 10 Veteran
St. Jude Contributor
I just put a 2600 in my '86. It would be a little high for an L98 if I were using it as a DD, but as a weekend cruiser its perfect.
With the extra revs from an Lt1 and just a bit tighter (2500 vs 2600) TC, I bet you would absolutely Love it.
When I changed the TC I could notice a pronounced difference. It was not Worse, or Better, just different. Somebody who is very familiar with early L98's would be able to tell I have a loose TC, but any non-guru would never even know I had done anything........'till they mashed the gas, that is.
Once I got used to it (about 12 minutes later) there was no question that it was a good move.
With the extra revs from an Lt1 and just a bit tighter (2500 vs 2600) TC, I bet you would absolutely Love it.
When I changed the TC I could notice a pronounced difference. It was not Worse, or Better, just different. Somebody who is very familiar with early L98's would be able to tell I have a loose TC, but any non-guru would never even know I had done anything........'till they mashed the gas, that is.
Once I got used to it (about 12 minutes later) there was no question that it was a good move.
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Safety Car
Joined: Apr 2004
Posts: 4,532
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From: Lahaina Hi
If it is your daily driver go with the 2000 if you want to weekend race go with the 2500.
I have a 3000 stall in my 86 and 3.33 in the rear fun from light to light ,a pain on the open road.
My 94 I installed a 2000 stall the c-beam cracks a little when I take off from a light but it is great on the road.
I have a 3000 stall in my 86 and 3.33 in the rear fun from light to light ,a pain on the open road.
My 94 I installed a 2000 stall the c-beam cracks a little when I take off from a light but it is great on the road.
Safety Car
Joined: May 1999
Posts: 3,651
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From: Atlantis
Cruise-In I Veteran
I have the RAPTOR and a 2800 stall converter on my street driven only Vette.
I like the 2800 stall... It get's the engine right on up to where it can make a little power.
I'd get the 2500 if I were you. Or a 2800 if they offer it.
I like the 2800 stall... It get's the engine right on up to where it can make a little power.
I'd get the 2500 if I were you. Or a 2800 if they offer it.
Burning Brakes
Joined: Nov 2003
Posts: 914
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From: Redding Ca
This is a question rather than a suggestion. When my Vette is on the freeway, 70mph is about 1700-1800 rpms' (700R/2.59 rear). How will a stall of say, 2400+ converter work at that highway cruising rpm? Seems to me there would be serious slippage and heat build up. At the least I would think a tranny cooler would be in order.
Waka, Waka, Waka!
Joined: Jun 2002
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From: Richmond Virginia
CI 4-6-8 & 10 Veteran
St. Jude Contributor
Originally Posted by GeosFun
This is a question rather than a suggestion. When my Vette is on the freeway, 70mph is about 1700-1800 rpms' (700R/2.59 rear). How will a stall of say, 2400+ converter work at that highway cruising rpm? Seems to me there would be serious slippage and heat build up. At the least I would think a tranny cooler would be in order.
The TC locks up in high gear. It is at 1:1 just like your old one.
Racer
Joined: Apr 2004
Posts: 298
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From: Springfield Missouri
Originally Posted by Fozzy_Bear
No change on the highway.
The TC locks up in high gear. It is at 1:1 just like your old one.
The TC locks up in high gear. It is at 1:1 just like your old one.
WoW! you learn somthing new every day!
if that's the case, why not get a 3000rpm?? For me, I'm either going 80 mph, or getting there with my foot to the floor.
Waka, Waka, Waka!
Joined: Jun 2002
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From: Richmond Virginia
CI 4-6-8 & 10 Veteran
St. Jude Contributor
Originally Posted by crkemppainen
WoW! you learn somthing new every day!
if that's the case, why not get a 3000rpm?? For me, I'm either going 80 mph, or getting there with my foot to the floor.
if that's the case, why not get a 3000rpm?? For me, I'm either going 80 mph, or getting there with my foot to the floor.
Safety Car
Joined: May 1999
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From: Atlantis
Cruise-In I Veteran
I agree with the Bear,
A 3000 stall is DEFINITELY going to cause increased tire wear.
But you WILL get more 'smiles per mile'.
2500 would likely be better.
3000 is a little past the 'sweet spot' for an L98 engine.
They start making pretty good torque around 2000 RPMS.
A 3000 stall is DEFINITELY going to cause increased tire wear.
But you WILL get more 'smiles per mile'.
2500 would likely be better.
3000 is a little past the 'sweet spot' for an L98 engine.
They start making pretty good torque around 2000 RPMS.
Race Director
Joined: May 2001
Posts: 14,165
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The absolute best thing that you can do would be to drive a similar car with a "loose" converter and see if you like it. A loose converter is all well and good for drag strip launches but for around town driving they can be really annoying.
Personally if I had an auto trans car I'd give up the track performance and keep the tighter converter simply because the car is a daily driver. It would promote better gas mileage and overall just a better feel.
Personally if I had an auto trans car I'd give up the track performance and keep the tighter converter simply because the car is a daily driver. It would promote better gas mileage and overall just a better feel.
Race Director
Joined: Oct 2001
Posts: 19,653
Likes: 428
From: Melbourne Florida
Cruise-In IV Veteran
I went with a 2400 stall converter...like so many others I wish I had gone with a 2800 stall...oh well...the streetability is just fine with the 2400...my advice is to go that way with the LT-1....good luck
