Jump to content
  • Welcome To Mopar1973Man.Com

    We can see that your guest and been lurking about. When you register on the Mopar1973Man.Com site you'll be able to interact with all the other members. This is the most friendliest Cummins forum you'll ever join. Take the time right now and  REGISTER  on the Mopar1973Man.Com this will open up many more options and functions on the website. Everyone is very friendly and helpful just ask questions and everyone will help you out the best they can. 

Oscar135

Tall gears and big tires... how to adjust my tune?

Recommended Posts

Posted (edited)

I've been fooling around with moparman1973's tunes on my 2nd gen cummins and figured smoke was just a way of life. However I was recently cruising threads and saw a comment alluding to a required step to adjust something when tuning for a truck with large tires and tall gears. I think I have the absolute worst case for this issue so help or guidance where to adjust would be greatly appreciated. My concern is not mpg but rather managing the fuel and timing curve to light the turbo well and hopefully minimize smoke

 

2001 5.9 valair twin disk nv4500 3.56 with 35" tires. 

SB intake, holset cheetah, afe intercooler and piping, banks high ram, 150hp injectors, 5" exhaust, quadzilla adrenaline using varieties of moparman tunes. 

Edited by Oscar135

Share this post


Link to post
Share on other sites

First off welcome to the site...

 

As for your setup your final ratio is too low. With 35 inch tires on 3.55 gears is going to produce 3.27:1 ratio to the ground. You need to change the tires or the axle gear to fix this. You need a final ratio of 3.55 to 3.73 to 1. Optimally if you changed to 4.10 axle gears it would give you 3.71:1 ratio final to the ground with 35 inch tires. 

 

Smoke is going to be a problem till you raise the final ratio. Like myself I'm running 30 inch tires and produces a final ratio of 3.69:1 with 3.55 gears. Turbo lights nearly instantly because of proper final gear ratio. 

 

8 minutes ago, Oscar135 said:

My concern is not mpg but rather managing the fuel and timing curve to light the turbo well and hopefully minimize smoke

 

Tuning will not fix a poor final ratio. The high engine loads to launch will always be there. Being your launching with 35 inch tires is like me launch in 3rd gear. 

Share this post


Link to post
Share on other sites

Have you followed the steps in the tuning guide to find what your 0 psi tune setting should be for your setup?  The extra load and bad final ratio won't help, but you should be able to clean up a good bit of smoke if you follow the guide.  

 

Mike's tunes will be a good place to start, but messing with the canbus fueling curve should help.   

Share this post


Link to post
Share on other sites

I did! But dang it is low. Using valet power to start with my 0psi level it needs to be at 65%. And can bus is backed off to 60%. I dropped timing a lot under 2000 rpm. Down to 12* and 16* for 1500/2000 respectively to help the turbo spin up. As well as using the low psi timing reduction. This seems to help as once I get over about 10-15psi the exhaust cleans up significantly.  Just one puff of smoke when I push the throttle then a slight haze if I stay on it. It's a slug off the line at 65%. But I noticed it responds much better jacking up 0psi fuel then dropping it to 65% by 2psi. It comes off a stop much better (i always used 2nd gear starts) and I'm off 0psi fairly quickly so I dont leave a plume at the stop. 

Share this post


Link to post
Share on other sites
34 minutes ago, Oscar135 said:

I did! But dang it is low. Using valet power to start with my 0psi level it needs to be at 65%. And can bus is backed off to 60%. I dropped timing a lot under 2000 rpm. Down to 12* and 16* for 1500/2000 respectively to help the turbo spin up. As well as using the low psi timing reduction. This seems to help as once I get over about 10-15psi the exhaust cleans up significantly.  Just one puff of smoke when I push the throttle then a slight haze if I stay on it. It's a slug off the line at 65%. But I noticed it responds much better jacking up 0psi fuel then dropping it to 65% by 2psi. It comes off a stop much better (i always used 2nd gear starts) and I'm off 0psi fairly quickly so I dont leave a plume at the stop. 

who's injectors?  my starting % with 7 x .012's ( ~200's)  was 68-70.  

Share this post


Link to post
Share on other sites

Adjusted 1500 rpm to 14* and my injectors are "150hp" which I think are 7x.010. But I'm also running the big fuel line upgrade, airdog150 lift pump and "high output" vp44. Advertisement said worth 100hp whatever that is good for. I have a feeling with all this fuel stuff it pumps way for fuel than the truck thinks it is. But managing it down low has proven difficult! 

Share this post


Link to post
Share on other sites

I was hoping that was not the case.  

 

There is no hope in cleaning up your injectors.  DDP does not use the stock spray angle, or a spray angle I approve of for a vp44 truck.   

 

Various people have tried to tune out the smoke and it never works, the injectors spray too much fuel outside of the bowl resulting in a dirty burn...... which REALLY sucks because DDP are extremely expensive.    

 

A set of run of the mill @dieselautopower injectors run 3x more clean for a given injector size.    

  • Like 1

Share this post


Link to post
Share on other sites

Well that's unfortunate! Is there some sort of advantage to the spray angle of DDP for a certain application or is it just messed up? Sounds like move 1 should be different injectors for the smoke management. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...