Geoff Weeks

It was the "mechanical" aspect that makes me say no.

Oh, Jojo, you led me wrong LOL. I don't know all the Mack engines like you. I still say 500hp out of a mechanical inline six below 14L is going to take some compromise in the lifespan. Even at 14L it is going to be a stretch. Electronic sure changed that equation.

Then drop the "mechanical" ( and 11L ) requirement and choose one of the fine electronics already made at that power and drop (stuff?) it in. As I stated any two are possible, not all three.

They do!

early days of the Big Cams and 3406 A and B sure, they need bearing rolls. later they were good for 1m or more if cared for. I have a 3406B in my Marmon with over 750K on the bottom end. Overhauled a NT88 at 1.4m and 750K on the bottom end which could have gone much longer on the bearings. Oils have got much better. Big Cam 3 oiling made a huge difference over that of the 1 and 2.

I was thinking inline 6 but yes there were others that broke the 500 hp barrier. I was incomplete in that statement. With the 3 "requirements" of 500hp, mechanical, and "bullet proof" remove any 2 and the 3rd is do-able. Remove only one and it is in the range of possibility. all three together and I don't see it happening.

There is a huge difference between what can be done with a mechanical engine and what can be done with electronics. You said you want a mechanical controlled engine, that limits what can be safely made in terms of power. At best mechanical can only have a speed based timing. That alone limits what can be done. Same on boost control. it would be a fixed map. If he wants that kind of power, then start with that powerplant. The hard work has been done, but there again it is not mechanical. Adding 10% to that would likely hold together, but may not. It wouldn't be the 1st powerplant that was discontinued/down rated after they came out when it was found they couldn't stay together long term. I stand by the comment that 11L mechanical engine @500 hp is not realistic, esp with your other requirements, of 500k to overhaul, and not being "babysat". The only fully mechanical truck engine to break 500 hp from the factory was the K-19 Cummins AFAIK. a 19L engine. Many did so when electronic controls and the items that are controlled were developed. All this to pull a "regional end dump" around? I pulled double your weight and much more wind resistance with ~430 hp. If you want an engine of any size that you can mash the go pedal and not watch the gauges, and I'm not sure there are any that fit that requirement, then it will a stock engine. drop in a 460 and play with that.

14L mechanical couldn't do that. 11L can't either. It wasn't until electronic controls came out did you see 12.7L come close. Why? what are you trying to do? realistic expectations are a must.

Makes sense and shows how out of date my info is. I never even remember working on something with an EGR, even thou they may have been out in the time-period I worked commercially, they were still going to the dealer for warranty work at that time. Air leaks are a PIA, they are not quick or 'sexy" to find or repair, just hard work with a lot of time chasing something you can barely hear, but they are what needs to be sorted out 1st before condemning big, relatively easy stuff to change.

This might help: Wabco Compressor manual

Wabco SS318 compressor. Most "compressor problems" are air system problems, not the compressor. People want to point the finger at one part, even if it is expensive, rather than take the time sort out why the compressor is popping off all the time, and passing oil. Intake of the compressor fed from intake of a turbocharged engine, means that even on the intake (downstroke) the pressure above the piston is above the crankcase pressure. This helps reduce oil misting in the outlet because there is no "vacuum" trying to draw oil up past the rings. A N-A compressor inlet does see a vacuum above the piston and can, under some conditions draw oil up past the rings. However that is not how most oil makes it to the compressor outlet. The block of the compressor is not water cooled, or really cooled at all. Only the head has coolant passages. Bendix list the normal outlet temp as "less than 360F" this is after the air has passed through the restriction of the exh valve port. Air temp and any oil vapor will be above that in the cylinder of a working compressor. Even engine oil will vaporize at those temps. Some will start to oxidize into hard coke. Vapor will pass out and condense back to liquid. There is a reason that duty cycle is limited to 25% MAX with lower being better. When air is not being used, running down the highway, you should go 15 min between cycles minimum. Just sitting idling blowing off every 2 min means it is almost continuously compressing. THIS IS WHAT YOU NEED TO FIX! when that is taken care of, the oil in the drier will be gone also. Being a single cyl compressor, and coke that gets stuck on the exh valve seat would prevent it from compressing at all. So that is not your problem. However it does sound like there is some leakage back through the discharge (exh) valve if you hear air leaking back through the compressor when the truck is shut off. There may be some varnish build up preventing a good seal and allowing the air to leak back through. However, unless you address the root cause, you'll be right back where you started in short order. How long does it leak? Could you be hearing the unloader leaking? The gov will supply air to the unloader when the system reaches full charge (120 +/-) and should stop supplying air once cut-in pressure is reached (usually 20-25 psi below cut-out pressure). If it only leaks for a short time, then put a pressure gauge on one of the unloader fitting on the gov, or the unloader line to the air drier and see if when that pressure drops to zero, that is when the air leak stops.

way too little info to make much of a guess, but if only leaks out of the compressor side of the air intake once pressure has built to cut-out, then it would be the unloader in the compressor that is leaking. If it leaks back all the time the compressor is running, then it could be an intake valve. Really need to know what compressor. Start by feeding shop air into the system and see where it is leaking out.

You nailed it, I can hear it in voice of the radio ad.

"SUNDAY_SUNDAY-SUNDAY" is how the ads of radio started, for the dragway. I remember them all these years later. Epping, NH

I was leased to two smaller trucking companies that were both started in the '30's and both were in bad shape by 2000, they were great people to work with/for. The internet killed them more than de-reg, or the internet was the final nail after de-reg weakened them. Not sure which way but they were both doing well enough in the 90's when I was with them.

I think the "center cab" trucks were a short term solution to a problem solved in another way. They seamed to be around in the 60's and 70's and mostly gone by the 80's. They could get into old cramped mfg districts with load that a semi could not. Those districts were likely service by spur rail line in older times. (can you imagine trying to get the rail-road to deliver a few I beams?) With more stuff moved by truck, if you couldn't get a std semi in you either moved or remodeled so you could, making the center cab an obsolete item. They also had almost zero value on the secondary market. You can't really re-use them for something else. Urban renewal, flight to the suburbs and beyond for cheap industrial land ended the need for them. I don't think I've seen a truck later than the Loadstar made into a center cab unless it was that purpose built truck I saw on I-79 all those years ago. It was so unrecognizable as to who made the chassie, might have been CCC (Crane carrier corp), so hard to date it.

From what I remember also the windshield was two piece gasketed so you could push one out and get out if the top and sides were blocked for some reason. Hauling crane beams on take-a-part trailers where the beam itself provides all the structure, makes you painfully aware about chaining down loads. Bridge girders are the same. Old "fish belly" girders were nerve wracking as you had to crib them up so high to clear.

Yeah, that is how I remember them, but it might also have been an earlier "R" series which had low flat fenders.

I don't think a driver had much input on those Loadstars. I have also seen one, that looked like a "carry-deck crane" without the crane part. Tiny drivers cab offset all the way to the left. and flat deck from the rear to the front. I saw it driving down I 79 south of Erie, Pa. I don't think a driver would much care for entering and exiting through the (leaky?) roof hatch.

yes, I've seen quite a few of them.

From what I can find the V6 GMC came out "new" for model year 1960, so production in 1959, so one would guess the 503 was done in the '59 model year.

interesting comparison. They list the RD501 at 3000 but it was gov at 2600 so not sure that was a one time test!

If I had to guess I would say the three are supply, line to brakes and exhaust line to outside the cab. here in the states, the same supply to the trailer supply button is also used for parking brake release Multi fuction valves get a supply from both the primary and secondary air system. But I have no idea how it is done in other parts of the world.

450 was the biggest dry lined IHC 6 the 501 was parent bore. IDK when the GMC 503 stopped being made in favor of the big V6 that came later. My parts truck came with a RD450 that was replaced with a re-newed (IHC's factory rebuild program) 406, long before I had it. Always wondered what it was like to run one of the big inline gassers.

LaPort Transport ran an all gas fleet of IHC and Ford until they closed sometime in the late 90's early 2000's. Before my time but do you know how the GMC 503 and the IHC 450-501 inlines stacked up against the diesels? I had a 406 in a parts truck for awhile. sold the engine for more than I paid for the whole truck.