AFC Mod Question-Less low end fuel!

Bobcat698 said:
I backed out the pre-load screw on the back of the AFC, and I figure I gained (lost) about 1.5mm of AFC foot reduction.

I still have quite a bit of low end fuel.
Also, I did some bench testing on my AFC and got full travel from the foot by 25 PSI, obviously if I went too tight rack travel was limited.

I have a 215 AFC, I may take the spring out of it and put it in my AFC, but I don't really rely on the spring to take care of low end fuel (you should be able to figure it out by watching this
That is with the old pump, however.
Click to expand...

I noticed a change from single to dual stack. Any changes in BP when you do this?
 
Snedge said:
I noticed a change from single to dual stack. Any changes in BP when you do this?
Click to expand...

Definitely, you go from having a total of 5 90 degree angles in the exhaust behind the cab to only 1. Spoolup was improved, along with power slightly, truck was more responsive.
 
The outside looking in: Did the change in the exhaust help the spool up or did the changes in the pump do that?

I watch allot of trucks but I do it on the net! Your I have watched many many times and it acted totally different this time, looks to me like you have the low end fueling issue cured!

Having said that there is nothing wrong with trying the 215 AFC spring, that's the one I have always run. A 180 spring tension will range from say 15-25 depending on how you set everything, a 215 spring will be from 30-45. For those of you that don't know what I'm saying, I'm talking about shop air (boost pressure) it takes in PSI to fully compress the spring.

Garrett, allot of people put too much lowend fuel in a pump by tighting the set screw on the back of the AFC. Some applications need say one turn preload, some two, I usually just run mine till it touches, I have a bigger pump and injectors than stock so there is no need and starting things off faster in the fueling arena.

Keep at the little things cause it sure seems like your doing good, the truck sounds good, runs good and pulls hard each time.

Jim
 
But 4 of the 90's are moving half of the volume. So you really only go from 1 to 3 90's but 2 of those 90's only have 50% of the air. Know question the offcenter single is better than a far right single. it would be nice to see some data.
 
Jim Fulmer said:
The outside looking in: Did the change in the exhaust help the spool up or did the changes in the pump do that?
Click to expand...


My thoughts exactly. Exhaust configuration means alot. Thats why I asked him about the BP. It is possable to help a larger turbo spool with more exhaust restriction.
 
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Jim Fulmer said:
The outside looking in: Did the change in the exhaust help the spool up or did the changes in the pump do that?

I watch allot of trucks but I do it on the net! Your I have watched many many times and it acted totally different this time, looks to me like you have the low end fueling issue cured!

Having said that there is nothing wrong with trying the 215 AFC spring, that's the one I have always run. A 180 spring tension will range from say 15-25 depending on how you set everything, a 215 spring will be from 30-45. For those of you that don't know what I'm saying, I'm talking about shop air (boost pressure) it takes in PSI to fully compress the spring.

Garrett, allot of people put too much lowend fuel in a pump by tighting the set screw on the back of the AFC. Some applications need say one turn preload, some two, I usually just run mine till it touches, I have a bigger pump and injectors than stock so there is no need and starting things off faster in the fueling arena.

Keep at the little things cause it sure seems like your doing good, the truck sounds good, runs good and pulls hard each time.

Jim
Click to expand...

Sorry Jim and others, I didn't mean to confuse you, the video is of a hook from when the dual stacks were on (obviously), and with the tuned 215 pump.
I now run a nicely tuned 180 pump.

I went to a single stack with the tuned 215 pump and the turbo was definitely more responsive.

I have 2 hooks on the truck since adjusting the screw more loosely to cut back fuel even more pre boost, I'll post videos soon.
 
Here is the first hook since cutting low end fuel a bit more.
I also went to a smaller turbine housing, lighted much nicer.
Click here to see Video

I did discover a boost leak after this hook.
Also, I blew the coolant hose off the rear plate on the block (the one that replaces the freeze plug in back and allows for better coolant circulation)
I dumped 3.5 gallons of coolant in 300 feet!
 
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