Nick Mack RDS Posted May 11, 2020 Share Posted May 11, 2020 (edited) I have recently inherited a 1988 Mack RDS and was wondering what I could do to up its horsepower. The truck is severely underpowered to my liking. I am used to driving a Pete with a 425 CAT. Would it be possible to put a CAT 3406e under the hood of my "88 Mack? I plan on swapping the transmission with an 8LL. Any comments, advise and help would be greatly appreciated. edit: I am now thinking a cat C12 would fit better. Edited May 11, 2020 by Nick Mack RDS Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/ Share on other sites More sharing options...
terry Posted May 11, 2020 Share Posted May 11, 2020 13 hours ago, Nick Mack RDS said: I have recently inherited a 1988 Mack RDS and was wondering what I could do to up its horsepower. The truck is severely underpowered to my liking. I am used to driving a Pete with a 425 CAT. Would it be possible to put a CAT 3406e under the hood of my "88 Mack? I plan on swapping the transmission with an 8LL. Any comments, advise and help would be greatly appreciated. Don't think there is near enough room for that cat. engine in a regular R model, the older R700's were used with cat and cummins engines. terry Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450907 Share on other sites More sharing options...
Nick Mack RDS Posted May 11, 2020 Author Share Posted May 11, 2020 12 hours ago, terry said: Don't think there is near enough room for that cat. engine in a regular R model, the older R700's were used with cat and cummins engines. terry Are you saying that the CAT engine would not fit? Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450908 Share on other sites More sharing options...
terry Posted May 11, 2020 Share Posted May 11, 2020 17 minutes ago, Nick Mack RDS said: Are you saying that the CAT engine would not fit? No I don't think it would, the R700 hood was about 8 or 10 inches longer, I sure somebody else will post with some info . terry Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450909 Share on other sites More sharing options...
Nick Mack RDS Posted May 11, 2020 Author Share Posted May 11, 2020 24 minutes ago, terry said: No I don't think it would, the R700 hood was about 8 or 10 inches longer, I sure somebody else will post with some info . terry Thanks for the info Terry! Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450911 Share on other sites More sharing options...
Quickfarms Posted May 11, 2020 Share Posted May 11, 2020 What engine, trans, rear ends/ ratio is in it now? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450915 Share on other sites More sharing options...
Nick Mack RDS Posted May 11, 2020 Author Share Posted May 11, 2020 It has a 350 hp mack engine in it right now and a eaton fuller 8LL trans Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450916 Share on other sites More sharing options...
Popular Post alex g Posted May 11, 2020 Popular Post Share Posted May 11, 2020 That's a good combo in a Mack in my opinion anyway. I've seen lots of 350s pull right along side with 425s. Is it possible you need a tuneup possible top end set or do you have boost leak. Could be easier than a engine swap 5 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450925 Share on other sites More sharing options...
Popular Post j hancock Posted May 11, 2020 Popular Post Share Posted May 11, 2020 The Dog will need a bit more nose to fit a CAT. Earlier RD754 models were CAT equipped but not in a 88 600 series. As mentioned, check the tune of your 350. There are some 350's around here that have plenty of grunt. 4 Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450931 Share on other sites More sharing options...
ws721 Posted May 11, 2020 Share Posted May 11, 2020 Remember, that was back when Mack was rated "to the ground" horse power. as mentioned here already, a 350 Mack should keep with a 425 Cat. We had a E6 350 that would whoop up on our 425 3406B. & that's no Lie 2 Quote Remember if it's got a hood it's no good! Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450981 Share on other sites More sharing options...
theakerstwo Posted May 12, 2020 Share Posted May 12, 2020 If i had to change engines i would go with a E7 and nothen wrong with a mack 350.Its that small number on the horsepower rating that gets some people thinking. 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-450999 Share on other sites More sharing options...
Maxidyne Posted May 12, 2020 Share Posted May 12, 2020 Back in the mid 90s I drove a CH with an E7-350 pulling a roll off trailer, weighed over 40,000 pounds empty and close to the legal limit of 80,000 loaded. Also had some Louisvilles with 425 HP Cats in the fleet, they were no faster and a good thousand pounds heavier. Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-451004 Share on other sites More sharing options...
james j neiweem Posted May 13, 2020 Share Posted May 13, 2020 Keep the 350 and tune or swap for an e7 400. My dumb ass opinion of course. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-451086 Share on other sites More sharing options...
Bullheaded Posted May 15, 2020 Share Posted May 15, 2020 My old 88 E6 350 pulled 140,000 pounds up 10 and 12% hills here as well and in same gear as my old 2013 Detroit DD15 505/1650 did and in same gear. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-451201 Share on other sites More sharing options...
mowerman Posted May 16, 2020 Share Posted May 16, 2020 i talked to a guy way back in 1983,,,,had a R600 with a cat...you might want to check further....good luck....but yes i also ran a 350 thermo in the 80s and i really liked it,,,real healthy engine...bob Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-451312 Share on other sites More sharing options...
david wild Posted May 16, 2020 Share Posted May 16, 2020 Your wasting your time a Cat will not fit in a RD/R Mack just measure the engine length and the space under the hood, now maybe if you put some puke little engine like a C10/11 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-451314 Share on other sites More sharing options...
Bullheaded Posted May 16, 2020 Share Posted May 16, 2020 Ya, not really worth it. You can build an E6 or E7 to run strong for cheaper than the conversion would cost. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-451316 Share on other sites More sharing options...
Quickfarms Posted May 16, 2020 Share Posted May 16, 2020 Ya, not really worth it. You can build an E6 or E7 to run strong for cheaper than the conversion would cost.What can you do to an e6 350? Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-451323 Share on other sites More sharing options...
Popular Post Bullheaded Posted May 16, 2020 Popular Post Share Posted May 16, 2020 Well before you even do any injection pump, injector or turbo work, try this. If your truck has been set to pass an emission test, etc......your puff limiter might be shimmed up to the point I have seen E6 and E9 motors completely gutless. What I first did to mine was take the air line off and plug it with a roofing nail. Yes it will puff black smoke on takeoff and every shift until the turbo catches up, but it will make a huge difference in throttle response which will make it feel stronger. It really woke my 88 up. But what I did later was I ran the air supply line through an air switch in my dash. (my truck was originally a 12 speed but switched to a 15.) So I used the 12 speed deep reduction switch. That way there the puff limiter could be kept shimmed up legal where it passed E-tests, then on the road I could just flip it off and run strong. Try that first, it's easy and cost nothing. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-451344 Share on other sites More sharing options...
bbigrig Posted August 12, 2020 Share Posted August 12, 2020 The Cat in my CL753 is a nice squeeze. No R6 series is going to take a kitty without some serious modification and lube. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-458263 Share on other sites More sharing options...
Mark T Posted August 12, 2020 Share Posted August 12, 2020 It used to be a comical thing seeing a regular four and a quarter Cat try'n to shake a good run'n 350. Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-458266 Share on other sites More sharing options...
Maxidyne Posted August 12, 2020 Share Posted August 12, 2020 Worked for an outfit once that had a CH with an E7-350 and a couple Louisvilles with 425 Cats on the same run, the Cats were no quicker than the Mack. Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-458273 Share on other sites More sharing options...
Popular Post grayhair Posted August 12, 2020 Popular Post Share Posted August 12, 2020 (edited) Next Up... Kamelbreath Harris Sorry, couldn't help myself. Edited August 12, 2020 by grayhair 1 2 Quote Link to comment https://www.bigmacktrucks.com/topic/62482-mack-rd-cat-swap/#findComment-458277 Share on other sites More sharing options...
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