[boomersrule55]

Looks like a decent build, except for the turbo intake, you might be able to rig up something temporary with a close rubber intake elbow and a cone filter... a egt gauge is a must since you will be pushing the motor to around 2100 with 32in diameter tires, 4.10's and a final drive ratio of 0.69 on a 47rh-re trans, that puts you around 70 mph and at 70 most other motorists will consider you impeding...!!! Isspro makes one of the best pyrometer available, they have been standard issue on the big trucks for decades... on the starting issue, make sure you have a good ground between the motor and the body-frame, I like to have two ground straps, motor to frame and frame to body, I have forgotten to reinstall straps on motor rebuilds and then experience hard or slow starting which will mimic dead batteries... or like your thinking, something going on with the fss, power to the fss should go thru a relay, I think it's like a 75 amp relay, the fss draws around 45 amps... safe travels...

 

[boomersrule55]

bommersrule55.

Thanks for the info. Ive been looking at cold air intakes, and haven't found one that is generic enough yet. Do you have any idea what the O.D. of the cold side/air intake of that presumably stock turbo is ?

On the tire size/final ratio , I was thinking that i would probably to a 37" tire or so based on what I've read so far on the 4BT RPM sweet spot for fuel mileage being around 1800, and fuel mileage really starting to drop off at any thing over 2000 RPM's.(hopefully for your sake you wont be stuck behind me when I take the maiden voyage this coming weekend if the thing only tops out at 70). Lol.....

Thanks for the suggestion on the Isspro pyrometer, I'll look for one. Do you by chance if the 4BT has a plug in the manifold for the probe ?

I have had the same issues with ground straps before, but hadn't thought about that, and it will now be closer to the top of the list of things to start with.

idk if you have a threaded port on your exhaust manifold, most guys drill and tap somewhere before the turbo... I have a 90 degree hot pipe which is cast iron and it does have a threaded port for a pyro probe, some guys don't feel a after turbo probe gives a true reading, I'm up in the air about this, because the big trucks I've owned all had after turbo probes installed in the turbo down pipe... as does my 12v pusher motor home, it stays around 900-1000 on grades and 500-600 on flats... I found this tire size/rpm calculator on the spicer america site that is very user friendly, just remember your final drive ratio is 0.69 if your running a 47rh or re, this might help you when picking out tire size or a axle ratio change...

 

[boomersrule55]

Actually, Cummins recommends the pyro probe to be after the turbo. The reason for that is that if the probe should break it won't damage the turbine wheel. That in itself would be a very rare occurrence. Post turbo is fine but you have to keep in mind that reading will be 200-300 deg lower than pre turbo. I'd think 1000 deg post turbo would be the limit. Most guy shoot for 1000-1100 deg pre turbo. Another rule that many don't follow is when you come to a stopping point, don't just shut down the engine. You need to let it idle until that temp drops to around 500 deg or a bit lower. You see those big rigs sitting at the truck stop with engines idling is not to just waste fuel. They are saving their turbo from damage.

Yes, that makes perfect sense, and after your post I remember reading about that years ago, the possibility of probes breaking off, never had one do that, but why chance it?