Low on power/boost

Tx tyre fryer

Tx tyre fryer

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Oct 4, 2015
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I'm having an issue with my truck, and I'm wondering if anyone that has experienced this has some ideas.

Stock head/cam 12 valve, 160 pump, built trans

My current setup is a Borg 366sxe and brand new 5x16 sac injectors. I'm only seeing 30-35 lbs of boost converter unlocked and maybe 40 locked. I think I should be seeing closer to 60.

Right now the truck doesn't hit hard and honestly doesn't feel a thing over 400 hp or so.

I'm running the stock spring in the afc and its modified for full travel so I wouldn't think that would be limiting me but I haven't tried gutting it yet to see.

Brand new rebuild on the trans by a reputable builder so I should be good there. It doesn't really feel like my converter is slipping and the boost doesn't really drop off like a slipping converter. It just feels like I'm hitting a plateau of some sort.

No exhaust leaks and no real boost leaks when I checked just a couple little ones, nothing major.

Truck drives fine and will get out of its own way decent enough but I know there's ALOT more in it. Any ideas?
 
You need to modify the AFC arm for more travel, then the stock spring coil binds before it goes far enough (cut the barrel not the foot). Then you need to replace the rack plug. Made a big difference on a 160 pump I was messing with. I've been using a inner valve spring from a set of BBC springs I cut down a little for the AFC, will let the foot travel far enough to take advantage of the rack plug at 40psi.
 
On a friends truck that had all that but still was down on power, racking the barrels made a big difference. I'm sure that's not always a good idea but was a high miles pump and kind of a last resort. Still runs good today and that was years ago.
 
Around 23* timing, 4K kit, 191s

I have ground the barrel, but I haven't replaced the rack plug yet, I will order one. I think I'll go ahead and order a couple springs to try as well

I've been thinking about racking the barrels as this isn't my daily driver and doesn't have to be super reliable, but I haven't yet because I'm not ready to pull the pump to have it benched just yet.
 
You can rack them while still on the truck, it won't be balanced. I've done this on two different trucks with no bad side effects, maybe just got lucky I know it's not the correct way but worked. Can't beat the price either.
 
A set of comp cut delivery valves is also a good bang for the buck, smokem or bigblue24 carry them. I'm trying out a set of 7mm valves now and seem a little cleaner but run close to the same.
 
Yeah I'm sure there's better delivery valves I could be running, but I really think there's something else going on. With the fuel I have it should be pushing this turbo harder. With the way it runs at 35 psi I think at 60 psi it would be an animal.
 
Update:
Tonight I gutted the afc and zip tied the shutoff solenoid arm up.
I guess the afc was limiting rack travel some because the truck is quite a bit stronger.
Boost still hovers around 35ish in 1st and 2nd unlocked but jumps to 38-45 in 3rd locked and around 45-50 in OD locked
Feels awesome, this 66sxe is great. Even with the afc gutted the truck is very easy to drive without being smokey and the turbo lights at around 1800.
I'm gonna go ahead and get a rack plug and some better dvs and see what I can do with this 160
 
Check that afc diaphragm to make sure it doesn't have a small leak while you're there.
 
I wouldnt mess with the barrels. Thats how they level the fueling to each cylinder. chance of running rough versus the .001% extra power you might net? Probably not worth it.
 
It made a lot more than .oo1% and idles perfect. It was a last resort to a high miles truck that wouldn't make decent power with all the proven ways. Every intention was to send the pump off later to be benched but it still runs so good.
 
I may try it once I get the money to have it benched, just in case.
I've got dialed in pretty good right now though, it hauls ass
 
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