So who has bumped the power on a 6CTA cummins

[Tornadogt]

CSM Davis - You are correct about the intake caps. I removed what I thought was a different design to find it was only an additional screen as you described. Thanks for setting me straight.

Took the truck for a quick ride with the cap removed. No more sucking sound through the screen. That motor really pulls in the air when wound up (put your hand near the intake). Ill get some pressure measurements later.

There are some post on here where people have used scoops on the inlet tubes. I am not sure on the brand but they looked pretty good and are designed to add air flow and still not suck in water..

 

[74M35A2]

I've also seen one of those intake top hat scoops and want one, and also wondered where they are obtained. If anybody knows, it would be appreciated. Thanks.

 

[Ford Mechanic]

This thread has lots about them and a couple of manufacturers for them. http://www.steelsoldiers.com/showthread.php?104204-4-quot-Ram-Air-Scoop-for-deuce
I put one made from a SS member on my M35 and can't remember who made it.

 

[Ford Mechanic]

Vintage Iron made the one I bought and if you check on the 5th page you'll see pics of it on my M35.

 

[Wildchild467]

I've also seen one of those intake top hat scoops and want one, and also wondered where they are obtained. If anybody knows, it would be appreciated. Thanks.

Are you going to paint it if you get one? You need to stop dragging your heels with you truck and we spend a weekend working on it and painting it. You'll love it!

 

[Hard Head]

0 to 5 will get you killed in my 923A2. If you see a car coming you are doomed. Seems like the transmission sucks the life out of it on startup. After 5 mph the engine revs up. Power falls off at 2000 rpm. That is as far as she revs. Reverse is 5x faster. Ideas?

 

[74M35A2]

Yes, read the previous 345 posts. Your common issue and its resolution is discussed. Reverse feels faster because it is a 10:1 ratio, vs about half of that in first gear. 2000-2200rpm is the governor limit on engine speed, the accelerator pedal is simply a request input, the governor is the ultimate authority on fuel rack position.

 

[Mike929]

Yes the gearing in reverse is insane vs. first gear. It really surprised me the first time I shifted into reverse to back into my yard and it pulled so hard in idle.

Hard Head,
Definitely read the first part of this thread about the trade offs of adding more power, and about the need for the turbo to spin up going forward before the engine has much power.


I'm presently working on mine after buying from GL, so not a lot of miles on the M939A2 series, but the information you seek is on the site in great detail.

 

[Jeep Nasty]

I followed clarke's step by step adjustment suggestions and I'm very happy so far. Took me about and hour and a half to do. Definitely seemed to have some more pep. I was able to get up to 70mph easily based off my gps phone speed app. My previous top speed was 64 and I had to be on a slight decline to get there. It was dark when I got done so I don't know how the smoke is yet. I personally don't want a bunch of smoke because I ran my exhaust down the side of the bed and out the side. I don't want people choking on it and drawing negative attention to the truck and hobby since I drive it everyday. So once I can evaluate the smoke in daylight hours I may have to dial it down with other adjustments.

one thing I can't figure out is how to take the extra slack out of the pedal. With the adjustments I did, my idle is at about 750 if I pull the pedal up from the floor with my foot after letting off. Normally releasing the pedal, it seems to not fully return without pulling it up with foot and idles at 1100. Will getting a new return spring fix this or shortening the current one fix this or is it the threaded rod adjustment or something else?

i was terrified of doing these adjustment by myself but it was super easy, I'm not one to mess with engine and fuel stuff, so this is new to me.

 

[PWM]

I had a similar problem with mine, I could not get the idle speed below 1000 rpm. I had to unhooked the throttle linkage and the linkage that goes down to the transmission (shown in the picture) to set the idle speed. Then I had to adjust the linkage so it didn't change the idle speed when connected. I also had to adjust the bolt under the throttle pedal so the linkage had it's full range of motion. It was a bit of trial and error to get it adjusted properly but all the joints in the linkage were rusty and in need of grease. This is when I noticed the vent cap for the power reservoir had fallen off , so I replace it while I was at it.

 

[ClarkeF]

JN,

if you only followed my steps there should be no difference really in smoke as that rear adjustment is post-boost fueling only. You need to adjust the top screw for pre-boost fuel which is where it will make some smoke. I haven't changed mine yet.

I do need to play with my idle some more - and probably lube and adjust all the cables too.

Clarke

I followed clarke's step by step adjustment suggestions and I'm very happy so far. Took me about and hour and a half to do. Definitely seemed to have some more pep. I was able to get up to 70mph easily based off my gps phone speed app. My previous top speed was 64 and I had to be on a slight decline to get there. It was dark when I got done so I don't know how the smoke is yet. I personally don't want a bunch of smoke because I ran my exhaust down the side of the bed and out the side. I don't want people choking on it and drawing negative attention to the truck and hobby since I drive it everyday. So once I can evaluate the smoke in daylight hours I may have to dial it down with other adjustments.

one thing I can't figure out is how to take the extra slack out of the pedal. With the adjustments I did, my idle is at about 750 if I pull the pedal up from the floor with my foot after letting off. Normally releasing the pedal, it seems to not fully return without pulling it up with foot and idles at 1100. Will getting a new return spring fix this or shortening the current one fix this or is it the threaded rod adjustment or something else?

i was terrified of doing these adjustment by myself but it was super easy, I'm not one to mess with engine and fuel stuff, so this is new to me.

 

[Ford Mechanic]

On a MW pump will adjusting the preboost star wheel affect the exaust temp? And is so how much generally does it affect it per ?click? or movement? Fixing to adjust mine tonight since I just got done with my boost and Egt gauges.

 

[nevrenufhp]

Star wheel doesn't have to be adjusted if you are going to adjust the fuel screw on top. If you adjust only the star wheel, the EGT may possibly go up 20 degrees.

 

[Ford Mechanic]

Will I get the same power and smoke without adjusting the preboost adjuster?

 

[nevrenufhp]

Right, once you adjust the top screw, it is basically pointless to adjust the star wheel. You will gain plenty with the top screw.

 

[Jeep Nasty]

Smoke is the same as before I turned it up. Truck definitely gets up to speed faster, though I will no be racing for pink slips anytime soon. Any good detailed write ups on installing a pyrometer and boost gauge?

 

[Ford Mechanic]

Right, once you adjust the top screw, it is basically pointless to adjust the star wheel. You will gain plenty with the top screw.

Gotcha, So I've adjusted the top screw some and I backed out of the throttle on my next test drive after getting 35 psi of boost and not having it at full throttle. So how much boost is too much for this engine stock to take or is it not capable of making enough to hurt it? The exaust temp hasen't even gotten over 1200*F yet!


Jeep Nasty....
What are you looking for in info on the pyro and boost install? I just got done with mine.

 

[Jeep Nasty]

Gotcha, So I've adjusted the top screw some and I backed out of the throttle on my next test drive after getting 35 psi of boost and not having it at full throttle. So how much boost is too much for this engine stock to take or is it not capable of making enough to hurt it? The exaust temp hasen't even gotten over 1200*F yet!


Jeep Nasty....
What are you looking for in info on the pyro and boost install? I just got done with mine.

I was looking for what you used for gauges and where you bought them, where you tapped in to put the sensors?

 

[Ford Mechanic]

Sure thing, let me get to some WiFi tomorrow and I'll do a new thread with both of them.

I think i'm going turn my pump down a half turn, it has GREAT power but I think the Trans will suffer in the long run. It really surges when it up shifts instead of pulling down the engine some.

 

[Ford Mechanic]

Hey nevrenufhp or anyone else, what has been your experience with the allison as far as holding up behind a turned up 8.3? Have you retro fitted any other Trans behind it and had better luck?