Simp's M915A1 Build Thread

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Hammer

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Btw, the double pto pump is rated at 22 gpm each at a high rpm.
Not sure we ever get an actual 22 gpm flow rate.
Kicking in the second PTO definitely speeds it up, but I doubt there is any pressure increase, so your strength while running a single pump should be fine.
 

WillWagner

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I haven't looked, but is the HT60 off a N14 motor a direct fit for the BC400?
Mine has a seal starting to leak, and I figured I would upgrade the turbo while I am at it.
And they can be CHEAP too.
https://www.amazon.com/Brand-HT60-TURBOCHARGER-CUMMINS-DIESEL/dp/B01LRAUVLY#customerReviews
Guess it depends on what parts you have changed. The turbo from an N14 was designed to work with the manifold on the N14, they have smaller ports, different outlet angles and the smaller ports on the heads. All this was done to increase velocity and make things start working faster, all for emissions and in turn, lower rpm performance. My guess is that if you put the N14 turbo on a BC 400, some had log manifolds, some the upswept type and some, if they were replaced, the pulse manifold, that was not introduced until "86, IIRC. THere might not be much improvement. Also note that the pressure fittings on the N14 were STORM, straight o-ring, metric and I do not know if the drain flange adapter for the T46a/b will fit the pattern on the N14 turbo, ASFAK, there was only 2 N14 manifold configs, auto/indust and marine. The N14 manifold will fit the standard 855.
 

simp5782

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Guess it depends on what parts you have changed. The turbo from an N14 was designed to work with the manifold on the N14, they have smaller ports, different outlet angles and the smaller ports on the heads. All this was done to increase velocity and make things start working faster, all for emissions and in turn, lower rpm performance. My guess is that if you put the N14 turbo on a BC 400, some had log manifolds, some the upswept type and some, if they were replaced, the pulse manifold, that was not introduced until "86, IIRC. THere might not be much improvement. Also note that the pressure fittings on the N14 were STORM, straight o-ring, metric and I do not know if the drain flange adapter for the T46a/b will fit the pattern on the N14 turbo, ASFAK, there was only 2 N14 manifold configs, auto/indust and marine. The N14 manifold will fit the standard 855.
Most of the big cam iii motors have the n14 manifold i have noticed. The big cam i i believe have the pulse unit
 

simp5782

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I haven't looked, but is the HT60 off a N14 motor a direct fit for the BC400?
Mine has a seal starting to leak, and I figured I would upgrade the turbo while I am at it.
And they can be CHEAP too.
https://www.amazon.com/Brand-HT60-TURBOCHARGER-CUMMINS-DIESEL/dp/B01LRAUVLY#customerReviews
Ht3b and ht60 will be about the same. An improvement ever what you have which is probably a t46. An HT4B is the big hoss that will let you increase injector size and pump increase. The ht60 and ht3b are 1100cfm movers. and HT4B and hx80 are 1650cfm or bigger. Stock intake on the 915 series trucks are 900cfms. That is my next mod is an air cleaner swap
 

Hammer

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Good info guys, thanks! I haven't started down this path of research yet.
Honestly, it kind of sounds like the HT60 or Ht3b will do fine for my needs, but I hate wasting an upgrade.
I don't just have an extra HT3b laying around like some others ;)
 

WillWagner

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#1, Log manifold, came on NTC 230 up to the 335. Will fit and work on the NHC
#2, 91-95 N14. Low mount, will fit on the NHC, but the plumbing will be funky. Ports smaller to increase velocity thru the turbine.
#3, N14 Plus, Nope, will not fit on the NHC, note the mounting bolt angles. Small ports for exh gas speed increase. See the wide joints?
#4, Standard up flow manifold, this is what came standard on the BC3. The upgrade, even under warranty, is pic 5. Note the joints are thin.
#5, Pulse manifold, upgrade from the #4 manifold. The joints are wider to accommodate seal rings on the two ends to eliminate exhaust leaks for, a) exhaust leaks slow the exhaust gasses down...an emissions thing, b) exhaust leaks are a warrantable covered thing as per Ca. SO, Cummins elected to have it be a covered item for ease of warranty and, in 1988, Cummins went to a 50 state engine platform, this manifold was standard in '86, prior to that, there were CA. engines and 49 state engines. This was introduced in around 1986 the BC4 and New BC4.

Both 4 and 5 will work on the NHC. #2 was not an option on the BC3. Plumbing will not switch over due to the low mount, someone would have to "make things work" in order to make it work. It will fit, but not a good option due to all of the plumbing nightmares and, the turbo mount flange is vertical, ever try to re index a turbo after time?
 

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simp5782

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Casting on the rear manifold of my 923 BCiii was 3065024 which is lists for n14 855. I had to get a replacement front section and i took it off an n14 in Louisiana. looks like pic 5 as what you have listed as n14plus
 

WillWagner

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2 and 5 use the same end sections, I labeled 2 wrong, saw that after I put the pics up. The ends on 4 will only work with 4, same for the log and 3. Progression time wise, 1, 4,
5, 2, 3.

There were some funky manifolds made for use in fugly trucks like Ford L series, Volvo W series, Mack, the manifolds hung the turbo very low and under 4-5 cylinders
 

simp5782

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Rear roller from a 916a3 is temporarily installed. Will maybe bringing it in closer to the back of the truck. Just gotta refigure the pintle hitch for incase i need to use it. Left it in its present position as i need to use a towbar here in the next few days.

Being that far off the rear won't hurt anything really. Just the best place with 2 exsisting bolt holes already in the frame.

Few more holes to drill on the winch mount plates.
 

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WillWagner

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Is there a way to pin it on in the location you want and when not in use the pintle is accessible? Kind of make it pivot up into position and pin/secure it for use and pivot back down and pin/secure it when not in use or needing the pintle?
 

simp5782

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Is there a way to pin it on in the location you want and when not in use the pintle is accessible? Kind of make it pivot up into position and pin/secure it for use and pivot back down and pin/secure it when not in use or needing the pintle?
I think it will clear like it is just fine. Little off the back of the truck but it wont have any weight on it other than the trailer neck a little bit. The roller weighs around 300# or so. I shouldn't need to use the pintle much at all.
 

simp5782

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Ordered some Unitruck mirrors off ebay. These are great mirrors that bolt in place of west coast units. Convex style so the field of vision is great. These morrors are heated. Great price of $56 for the pair with shipping from London. They are 24v heaters but no big deal.

Got my fan clutch control re wired and set with a selector switch for normal or manual on or manual off.

Swapped out some of the white light dash bulbs with some blue ones.
 

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Ajax MD

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Do those mirrors negate the need for the small, round wide-angle mirror that usually pairs with the west coast mirror?
 

simp5782

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welp. went on a shopping spree on ebay and stocked up on filters. 2 transmission filters (HF6243), 2 fuel filters (3399289), 4 main oil filters (LF3380 Microglass extended use version) for $100 all in fleetguard. waiting for the bypass filters to show up (LF777) They were $15 each. Going to replace the air dryer filter this weekend ($15).

Gotta get the heater mirrors wired up this weekend as well. Long way to run them to the fuse panel. Building an switch panel to tie everything into under the dash.

Ordered a replacement upgrade air filter (49140 outer/ 49141 innter) . Near same size specs as the stock unit (stock unit 2528/2527) but with alot more CFM rating. - Stock filter is rated for 1200cfm . Upgrade is rated for 1990 so this should drop some EGTs.
 

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Hammer

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#1, Log manifold, came on NTC 230 up to the 335. Will fit and work on the NHC
#5, Pulse manifold, upgrade from the #4 manifold. The joints are wider to accommodate seal rings on the two ends to eliminate exhaust leaks for, a) exhaust leaks slow the exhaust gasses down...an emissions thing, b) exhaust leaks are a warrantable covered thing as per Ca. SO, Cummins elected to have it be a covered item for ease of warranty and, in 1988, Cummins went to a 50 state engine platform, this manifold was standard in '86, prior to that, there were CA. engines and 49 state engines. This was introduced in around 1986 the BC4 and New BC4.
I have #1 on my BCI engine.
How much of an improvement would it be to swap it out with #5?
 

simp5782

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Air filter modification completed. Had to cut out a few of the internal fins. About 10mins worth of work. Massive filter cfm increase from 1200cfm to 1990cfm. I may even add an extra intake port to it as well
 

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