Let's build a tow motor!

[Broncman]

92 intercooled factory stock. This will be used strictly for towing using an NV4500 . Current axle ration is 3.73.

4 inch exhaust and gages, grid heater delete and coolertubz type intake , water injection are all planned.

I have money for turbo and injectors as well. I recently did a job for someone and now have the pick of a BorgWarner turbo for my upgrade. SOOOOO...which one? An S300 of some type?

Turning up the fuel screw VS the next size up on injectors? Which of those are better for lower EGT's? Don't mind spending the money if needed, but not just to say "oohhh look what I got!"

Lowest possible EGT's while pulling grades are my goal. I can upgrade radiaotrs and intercoolers of needed as well.

Sooo, What is the ultimate tow setup (NO RACING ETC) for single turbo's. My pocket is starting to burn...

[cougar]

Fuel = heat. So cooling is everything. I have my own theories that a lot will disagree with, but;
High volume (NOT PSI) turbo with a large exhaust housing. Provides a lot of excess air for a cooler fuel burn and a larger exit to get rid of the heat.
Larger intercooler. (Power Stroke) lowers the incoming air more so the outgoing is lower.
6 or 7 small holed injectors. (.010"-.011") Better atomization of fuel at lower volumes for a more efficient burn.
Keep the fuel screw turned down. Remember, fuel = heat.
M&H M2 or Denny T stage 1 fuel pin. Provides a staged fuel delivery with the correct star wheel setting.
Water/meth is a good cooler downer.
4" exhaust.

[Broncman]

Those are my thoughts as well, but just not sure on sizing etc.

So bigger injectors could possibly atomize better? Which injectors should I start looking at? Again, this is not a horespower driven effort , but the most I can build reliably at a decent EGT. if it is only 250, then so be it.

Bigger radiator and intercooler are in the plans.

[cougar]

Those are my thoughts as well, but just not sure on sizing etc.

So bigger injectors could possibly atomize better? Which injectors should I start looking at? Again, this is not a horespower driven effort , but the most I can build reliably at a decent EGT. if it is only 250, then so be it.

Bigger radiator and intercooler are in the plans.

No, not bigger per say. Just more, smaller holes. You can go up a little in total cross sectional area without hurting your EGT. The stock intercooled injectors are 6 holes, .009" in diameter. The "performance" injectors are typically 4 to 5 larger holes .012" and up but they create heat that's harder to keep away from when towing. My 91 is my towing rig and that combination works fairly well, but not perfect. I'd like to be able to hang out in 5th longer without having to downshift into 4th on every hill. The Bosch +40s I'd like to replace with a set of 7x.010"s and get a water/meth setup.

[dazedandconfused]

I believe a cam would also make a nice difference as well.

[oldestof11]

Get some 7x.010's. Same size as 5x.012's I believe but better EGT's and smoke.

Good towing turbo would probably be something with a 14cm housing. 16cm I would think be too large and won't help spool up the turbo as quick as you need it. Why? You need to be in the efficient island on the turbo's map for optimum cooling and CFM's. Too big of a exhaust housing results in lag and dumping too much fuel getting EGT's to rise quicker. If drive pressure/Egt's becomes a problem, then you have something else wrong.

For a towing turbo, I would think something like a 62/68/14 would be optimal.

[Broncman]

Ok, so I have been studying the injector charts and stickies. i see 190's coming up a bit for a slight nudge over stock. I really do not want to put a cam in because I have the motor in. So i am mainly looking at injectors, turbo and possibly exhaust manifold.

Keep talking to me about injector sizing and turbo's... Starting to grasp nozzle sizes and areas etc. What can anyone tell me about the Borg Warner S 300's? I have a real good line on the Borg Warner line. 14 housing seems to be the direction as well.

Thanks guys for all the info, keep it coming.

PS: Any quick rule of thumbs for the cummins to map your turbo with? This is all so new to me...
Should I get every thing in but the turbo and see where my boost level ends up and then try to figure out where my pressures etc are? So often tuning ends up requiring you to change parts from your original plan and that translates to money. So the better informed I can get, hopefully the less do overs I have....

[Broncman]

Last night I got a friend of mine who is a Borg Warner Turbo engineer to come over and go over my setup. He helped me understand a lot. He took my info and all the stuff I want to do and is going to have an application engineer lookat it and help me figure out what I need. The App. Engineer is a turbo fanatic as well with several turbo projects of his own. I pulled up all the data I could find on some of the S300 variants such as the Super B. Can't wait to get this thing going!

[Tacoclaw]

Sounds like you got friends in high places!

Please share what he tells you with us if you don't mind, there's not a lot of actual engineering that goes into the mods around here. It's just mostly what's already been proven to work, but with no data to explain it.

[ellis93]

Sounds like you got friends in high places!

Please share what he tells you with us if you don't mind, there's not a lot of actual engineering that goes into the mods around here. It's just mostly what's already been proven to work, but with no data to explain it.

^^^What he said
I wish I had an application engineer in my pocket I might just keep all my brain farts to my self
I pull with my truck quit a bit and I'm very interested in your findings on this.

[crewcab59]

I run an s300 62/65/14 and when i pull my 32ft 5er toy hauler it weighs in about 13000 lbs. i have 5x14 though but i tried taking them out and put in the stockers and it wouldn't boost at all and was worse for power and egt ???? even turning down the pump didn't work (way too gutlass) The main problem is it wont hold boost at traveling speed so the egt's creep right on up. quit fast it will easily go to 1400 deg. from a stop light, or up a windy hill so you can floor it, it will stay under 1100 with 30 lbs of boost but soon as you let off, the boost is about 7 to 10 psi. from there useless cause. I used the hy-9 for a bit and pulling it was perfect for that it never dropped below 20 psi, I blocked the waste gate and ran it up to 40 lbs of boost. but then at freeway speeds it couldn't handle it eather and would bury the gauge ( ya i heard i was lucky not to scatter the hy)so my next step is twinns. But for someone who doesn't have a turbo yet I would maybe go with a 62/12 or 64/12 or something that will hold boost at lower rpm's (without the trailer none of this is relevant) I hope my troubles help someone else. thanks, good thread

[ahale2772]

I also think a cam would be good for towing guys...

VE's like power down low, why not give them flow and low RPM volumetric efficiency so that they can make clean cool power.

if I was to build a tow motor I would focus on cam, cylinder head flow, and cooling

[Broncman]

I run an s300 62/65/14 and when i pull my 32ft 5er toy hauler it weighs in about 13000 lbs. i have 5x14 though but i tried taking them out and put in the stockers and it wouldn't boost at all and was worse for power and egt ???? even turning down the pump didn't work (way too gutlass) The main problem is it wont hold boost at traveling speed so the egt's creep right on up. quit fast it will easily go to 1400 deg. from a stop light, or up a windy hill so you can floor it, it will stay under 1100 with 30 lbs of boost but soon as you let off, the boost is about 7 to 10 psi. from there useless cause. I used the hy-9 for a bit and pulling it was perfect for that it never dropped below 20 psi, I blocked the waste gate and ran it up to 40 lbs of boost. but then at freeway speeds it couldn't handle it eather and would bury the gauge ( ya i heard i was lucky not to scatter the hy)so my next step is twinns. But for someone who doesn't have a turbo yet I would maybe go with a 62/12 or 64/12 or something that will hold boost at lower rpm's (without the trailer none of this is relevant) I hope my troubles help someone else. thanks, good thread

Hmmm...So we have too much fuel when on the low side of the turbo? I would think at very low load levels and no boost that one would see no egt problems? Out of the map of the turbo? Would a smaller set of injectors help in this situation ? 5x12??? or a smaller turbo like the Super B with the 57 work better? God this is all confusing but I am starting to know enough to make it REALLY confusing

Would a 12 housing help on the boost at traveling speeds in your situation with a 62/65? A compromise between a 9 and 14?



As far as a cam? I am sure that would help, but really do not won't to pull the front of the engine off this early in the game! God knows what I could screw up then

[crewcab59]

The turbo was a 57/65/14 and HTT bored out the compressor to a 62 and that helped a lot, I had the stock injectors in for awhile and i ran the fuel pin in and out, either to gutless or too hot??????? I also messed with the star wheel....no luck. down low in rpm's the egt's outrun the boost gauge( it will go to 37 psi) ( i think a 62/12 would be better) I guess it's a good excuse for twins surly that will fix it, and you are right the more I learn about it the less it makes sense.

[Tacoclaw]

VE's like power down low, why not give them flow and low RPM volumetric efficiency so that they can make clean cool power.

if I was to build a tow motor I would focus on cam, cylinder head flow, and cooling

I agree with this completely. At the end of the day, boost is a way to strong-arm efficiency out of an engine. If you find yourself operating at a range where boost isn't present, you need to either find a way to get boost there, or increase the efficiency of your engine without it.

While getting boost in that area with housing changes would seem like the simplest and cheapest method, it usually comes at the price of sacrificing efficiency elsewhere in the operating range.

I myself plan on a ported head to be my next mod, but I don't see that happening for a couple years.