How Much HP can a 4+3 Handle?
Race Director
Joined: May 2003
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Originally Posted by doogie
How much Horsepower can a 4+3 transmission take?
this is the question i would love to know as well, as i am in the process of doing heads/cam/intake, and possible a 75-100 shot of NOS.
only 450ft/lbs, where did u get that figure from?
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Torque is more worrysome than horsepower. Horsepower is a product of torque over time. I'm making ~450 ft/lb right now and its fine. Keep in mind that the '88 Callaway Twin Turbo Corvettes used the 4+3 and they made nearly 600 ft/lb. 
Race Director
Joined: May 2003
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Originally Posted by scorp508
Torque is more worrysome than horsepower. Horsepower is a product of torque over time. I'm making ~450 ft/lb right now and its fine. Keep in mind that the '88 Callaway Twin Turbo Corvettes used the 4+3 and they made nearly 600 ft/lb.
brian, what else was done to the callaway 4+3? any idea?
Team Owner
Joined: Mar 2000
Posts: 83,383
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From: Boston, MA
Originally Posted by 88BlackZ-51
brian, what else was done to the callaway 4+3? any idea?
Race Director
Joined: May 2003
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Originally Posted by scorp508
Not much from what I know. I think the line pressure in the overdrive was increased a little bit to give it a snappier shift.
that sounds positive, because when i am done with my motor it will be around 600 ft/lbs
Pro
Joined: Mar 1999
Posts: 678
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From: Oslo, Norway
Hi. I have an 85 and was interested in exactly the same. As I knew that Callaway had much more than the 450ftlbs I phoned them. They said that it is recommended to have the overdrive in 1:1 when releaseing full torque(power) when starting and then enable the OD. Gearzone says the 4+3 manage 450ft.lbs and the reason why they seem to manage more with street tires is the tires will slip much earlier than getting to the 450ft.lbs when starting the car from 0 mph.
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Race Director
Joined: May 2003
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Originally Posted by jan-erik
Hi. I have an 85 and was interested in exactly the same. As I knew that Callaway had much more than the 450ftlbs I phoned them. They said that it is recommended to have the overdrive in 1:1 when releaseing full torque(power) when starting and then enable the OD. Gearzone says the 4+3 manage 450ft.lbs and the reason why they seem to manage more with street tires is the tires will slip much earlier than getting to the 450ft.lbs when starting the car from 0 mph.
maybe i am slow today, but just dont get what u are saying
Le Mans Master
Joined: Dec 2002
Posts: 5,270
Likes: 3
From: Seattle Area WA
What I believe he is saying is:
1:1....in other words overdrive off when laying down the throttle
Then apparantly gearzone said the reason they can handle more is because tire slip reduces forces on the transmission. Just like how tire slip saves you from breaking u-joints everytime you launch. I don't know HOW true this is, mind you gearzone is a company and while yes tire slip is a stress-relief I don't know if all they can handle is 450 ft/lb. I would tend to believe with a 600ft/lb motor they could actually handle a lot more. The real variable is the OD the Super T-10 should take it like a champ.
1:1....in other words overdrive off when laying down the throttle
Then apparantly gearzone said the reason they can handle more is because tire slip reduces forces on the transmission. Just like how tire slip saves you from breaking u-joints everytime you launch. I don't know HOW true this is, mind you gearzone is a company and while yes tire slip is a stress-relief I don't know if all they can handle is 450 ft/lb. I would tend to believe with a 600ft/lb motor they could actually handle a lot more. The real variable is the OD the Super T-10 should take it like a champ.
Race Director
Joined: May 2001
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Would it not be safe to say that the weak zone is the overdrive unit anyway. I've always been under the impression that the 4-spd in and of itself will take almost anything you throw at it, while the overdrive is about as strong as a wet paper bag.
Of course proper maintanence goes a LONG way in preserving the life of any components.
Of course proper maintanence goes a LONG way in preserving the life of any components.
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
B2K = RPO Code for the Callaway Twin Turbo Package
Absolutely. Also added into the mix is that the 86-88 O/D units are far more reliable than the OEM 84/85 ones are.
Originally Posted by Nathan Plemons
Would it not be safe to say that the weak zone is the overdrive unit anyway.
Absolutely. Also added into the mix is that the 86-88 O/D units are far more reliable than the OEM 84/85 ones are.
Burning Brakes
Joined: Jan 2002
Posts: 993
Likes: 4
From: Glen Burnie MD
Originally Posted by SurfnSun
SKspeed also makes bronze clutches now that are supposed to be a lot stronger. Forum member 8388 has put them in his 88 b2k and said they work very well.
Thanks.
[RICHR]
Burning Brakes
Joined: Jan 2002
Posts: 993
Likes: 4
From: Glen Burnie MD
Originally Posted by SurfnSun
SKspeed also makes bronze clutches now that are supposed to be a lot stronger. Forum member 8388 has put them in his 88 b2k and said they work very well.
Thanks.
[RICHR]
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Originally Posted by SurfnSun
SKspeed also makes bronze clutches now that are supposed to be a lot stronger. Forum member 8388 has put them in his 88 b2k and said they work very well.
I talked to Brian at SK Speed about these. He flat out said they are vicious on the tranny and you MUST use the clutch when engaging O/D after installation. He recommends them for serious road racers.
Team Owner
Joined: Aug 1999
Posts: 24,017
Likes: 634
St. Jude Donor '10
Originally Posted by rrubel
Got more info on them? Not familiar with SKspeed; if it's www.skspeed.com I didn't see anything about clutches or transmissions at all.
Thanks.
[RICHR]
Thanks.
[RICHR]
http://www.skspeed.com/aboutsk/transshop/default.asp
