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When I saw this at the museum, I was amazed. This truck is immaculate. When I looked at the motor, I see valve covers like a V8 would have, but it looks like a 6 cylinder? It confused me. Then I see on the hood Maxidyne 650. What's the scoop on this motor and truck? Specs? I have never heard of or seen a 650 Maxidyne so was it a prototype? It's obviously rare.

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Mack was developing a "big 6" and the prototype was sitting in the museum. It used similar components from the E9 but abandoned the project. I thought there was only one engine built.

Ken

PRR Country and Charter member of the "Mack Pack"

Well there aren't any E9 parts on that truck, that's an E7 mechanical engine. I have seen the Mack Big Six its a 14 liter six cylinder and there was only one "left" after early tests so says David McKenna Mack power train VP. That truck has a billet badge on the side of the hood made by Nuss Truck Group supposedly they built that truck and cranked it up then made the badges to go on the hood.

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

Hagerstown Mack built many engines for Merlin Marine that were ME7 engines rated from 600-800hp for use in marine applications. So building an E7 with a rating like that (if it is an E7?) is no real strech. The marine E9's were rated up to 900hp. All built by Mack and finished with stainless cooling systems by Merlin Marine in the 90's

Mack ran a lot of prototypes. Overnite was one of several fleets chosen for endurance testing.

I'm not familiar with this effort, but it certainly seems apt to call it a second generation Mack "Big 6". Pedigreed bulldog engineering impresses.

The original 855 cu.in. (14 liter) "Big Six" was dubbed the Turbodyne by legendary Mack engineer Walter May.

I hesitate to think it was based on a marine spec engine, because they wouldn't have a chance at passing emissions. Why bother on-road endurance testing?

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yup there was a sign, just like Gary Mahan has in front of all his trucks. its said something about the engine was built with performance components by the Hagerstown boys, I remember that part. not worded like that but I know it said something like that

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The Mack Big SIx used E9 heads and pistons but not cylinder kits it was a long stroke engine not the short stroke of the 90 degree V8, Bill at Winrock Truck Parts had told me once the few testing engines were sold off to scrap and he had ended up with two but that they were not running and Makc had no parts to repair them so after a couple years one went to a Mack collector and the other to scrap and the only remaining complete Big Six is in the museum. The engine in the RW up top is an E7 look at the intake manifold and valve covers, Mack E7 engines were built for Marine and Industrial use in high horsepower variants and a big HP E7 could be made using those parts if you had the cash, same for an E9, there are E7 and E9 Marine engines over 750hp still in use today. The french army still has several E9 530/550HP rating engines in old APC's however I have been told they are no longer in use and are set to meet the scrapper so everyone needs to start makling cals and emails to get em back to the U.S. if we can. I have a Magazine somewhere with an AD for Mack Marine engines with pics and specs for both E7 and E9 engines Ill try to find it later.

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"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

Mack ran a lot of prototypes. Overnite was one of several fleets chosen for endurance testing.

I'm not familiar with this effort, but it certainly seems apt to call it a second generation Mack "Big 6". Pedigreed bulldog engineering impressives.

I hesitate to think it was based on a marine spec engine, because they wouldn't have a chance at passing emissions. Why bother on-road endurance testing?

When someone fiddles with the Injection pumps, turbos etc to get big power out of an E9, CAT 3406, or anything......Do you seriously think they give a crap about the emissions on it???? The engine was probably a nice little side project for the boys at Hagerstown put in a "privately owned" truck. NOT meant for production... If I'm not mistaken Pulling trucks like the Buckeye Bulldog had engineering from Hagerstown involved. I'm pretty sure in the Buckeye's case emissions were a complete afterthought. The Marine set up would be an excellent blue print for that motor.

Easy there Ray, lets get it home and drive it around a litle bit vefore you buy injectors and a turbo aight. LOL! I know there was an Old E6 4valve 350hp powered RW TriAxle Dump around here several years ago with different injectors,turbo and some pump work that had the rwhp dyno sheet in the truck he would show you after he passed you with a load on, it was 467hp if I remember right, and I think that makes around 560hp flywheel, of course nobody can tell you what driveline hp loss % actually is without going thru the gear reduction numbers, etc.

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

Ive heard everything from 8% to 28% for driveline loss and I cant ever figure it out so I just guesstimate unless I can get someone to tell me what they think they are making. I would guess it was closer to 500 than 560 flywheel but it was a bad dude for sure. I gotta get STAXX going on putting my 85 on the rollers to see some before and after turbo and injector numbers, if my clutch holds out.

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

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