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As time moves forward, so does automotive technologies. The 1980's brought us 4 speed automatic transmissions. The 1990's brought us the mighty 4L80E transmission, good for big blocks, and can be built to handle 1,000 HP. They can be adapted to run behind Ford, Chrysler and more engines. Hot rodders have always found a way to adapt newer better technologies.
Today, folks are taking the ZF 8HP transmission and doing the same. It’s used in BMW, Stellantis (Dodge, Jeep, Ram, Alfa Romeo, Maserati, Chrysler), Jaguar, Land Rover, Aston Martin, Bentley, Rolls-Royce, Toyota (Supra), and Audi cars. Hellcats have it.
The 8HP90 version handles 1,000 HP in stock form. Compared to the GM 4L80E, it’s about the same size, weighs a little less, has much lower parasitic power loss, has super fast gear shifts and creates much less heat. It’s very low first and second gear ratios allow full torque converter lock up at 1,200 RPM without making the engine lug which further increases efficiency and reduced fluid heating. Folks who’ve done the swap say it feels like they’ve gained 100 HP.
What’s all needed to make it work? Well, there are a few steps that, for now, are a bit costly-but as with anything new to the aftermarket, costs will go down as more support is established.
A kit adapts the traditional GM bell housing patterns and torque converter. A custom drive shaft with a slip yolk is needed. An aftermarket transmission controller is needed. All told, it could be a $6,000.00 job. Let’s remember, a properly built 1,000 HP 4L80E with torque converter can easily be six grand-or more.
There’s at least one aftermarket EFI system, MaxxECU from Sweden that offers 8HP control. They have US distribution in Kentucky. This helps reduce the cost.
It’s just a matter of time. These units will become more prevalent in the auto salvage industry. Swap components and electronics will be developed. Overall costs will come down. This swap will slowly become more common.
Last edited by Paul Bell; Feb 8, 2026 at 06:19 PM.
My man @Project GatTagO has been on board with these units for a while now, and has been involved with several installs AND tuning. His enthusiasm and results has me looking for an 8HP90 myself to put in an upcoming OBS build for myself.
@BruGTP that Fairlane swap in the video is Brian A's, he's in Lombard.
Yeah, I’m familiar with the Fairlane and some of his other projects and research on the subject. That’s great he’s in the area. I’ve read all the theory and seen plenty of muscle car builds with the 8HP but haven’t seen an actual FBody yet with one. What I’d really like to see is one with and aftermarket PCM and electric throttle body that can do rev-match on downshifts.
A 8HP70 can easily be built to handle more power than the 8HP90. And it's slightly smaller too.
A used RWD 8HP70 can be bought for as little as $400. The 8HP90, $4,000.
There are ridiculously expensive rebuild kits on the market for upwards of $9,000! Most have frictions & steels, a few billet drums & hubs, filter/pan.
All this can be bought separably for under $2,000. Alto is the preferred friction choice. The rebuild is easier than a 4Lx0E and there’s vids of it being done in garages.
So, for around $3,000, a high HP capable transmission with new innards can be had.
Blue Print Engines uses a Austin Martin 8HP70 case that has been modified to remove some of the bosses from the main case. The case is mated to a bell housing that Blue Print Engens casts in-house.
I joined a few Facebook 8HP groups to see what everybody is doing and the parts they’re using.
An Alto Power Pack frictions & steels kit is the preferred upgrade kit. Apparently, there are a few very overpriced kits that use this kit and they buy them all when Alto has stock.
I purchased this Alto kit. I needed to see if it has the upgraded backing plates, yes, it has one of two that are recommended to use.
The billet items are made from 7075 aluminum and are available on Ebay.
From what I found, this is what’s included in some of those $6,000 and higher “performance kits”. The billet parts address any weak point of these units:
8HP Transmission 
