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4th Gear
Joined: Jan 2021
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Question: I have a 1986 Corvette that I'm thinking of replacing the engine with a crate engine with around 400 HP. My question is the car currently has a 4/7 manual overdrive transmission. If I was to put a crate engine in would the transmission be able to handle the additional power? What problems may come up with adding a new engine with about 150 more horsepower than my stock engine?
Racer
Joined: Apr 2020
Posts: 252
Likes: 83
From: State Of No Return
I never owned a Doug Nash transmission, but from what I understand from others is that the OD unit has had its fair share of issues since relatively new, and now you want to mate a new 400 HP crate engine to a 35 year old transmission design that had issues with a 235 HP motor.....I'm thinking that it's not going to end well, but hey that's just me....Maybe, someone with some first hand experience of owning the Doug Nash can chime in....
Last edited by mskc3; Jan 30, 2021 at 02:20 PM.
Le Mans Master
Joined: Sep 2004
Posts: 6,018
Likes: 565
From: Conroe Texas
yep, it's gonna take a dump. and a big one. i put headers only on my 87 4+3 and within a month the ole doug nash died. and i didn't even get on it hard. it was when i traded it in on my 89' 6-speed back in 11/90 so the 4+3 wasn't that old.
Last edited by Sleazy Rider; Jan 30, 2021 at 02:41 PM.
Thread Starter
4th Gear
Joined: Jan 2021
Posts: 4
Likes: 0
Thanks for the info. I will take your advice and if I change the engine change I'll do the trans too. I've had the car since new and have never had a problem with trans but adding a lot more HP probably will do it in!
Safety Car
Joined: Oct 2007
Posts: 4,426
Likes: 229
From: Pennsylvania
If your overdrive transmission died one month after you installed headers, I'd say it certainly had nothing to do with the headers. Not even close. Headers aren't going to give you so much raw power that your overdrive transmission will be destroyed. It most likely failed because of operation misuse, lack of maintenance, or failed parts due to age.
