No Top End Power?

CaseyF

CaseyF

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Dec 12, 2010
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I posted this on Cummins Forum, but what are ya'll doing for more top end? I'm currently getting beat by a stock OBS Powerstroke with 150hp (if that) injectors. I just don't think my truck feels like it has the top end it should.
 
It has the 3200 gsk. It's also getting full throttle travel also. I'm thinking about skipping a gear plus some on the timing and see where that gets me. It barely hazes at WOT, so I don't think it's getting the fuel it needs on the top end. It has an electric fuel pump too, 14psi/idle and 10psi/WOT.
 
What turbo are you running if it cleans up the smoke with a turned in fuel screw and no AFC?

Also what's your gearing?
 
What injectors and turbo are you running. That would be a big help, in helping us give you a pointer or two.

Eric
 
CaseyF said:
It has the 3200 gsk. It's also getting full throttle travel also. I'm thinking about skipping a gear plus some on the timing and see where that gets me. It barely hazes at WOT, so I don't think it's getting the fuel it needs on the top end. It has an electric fuel pump too, 14psi/idle and 10psi/WOT.
Click to expand...

How did you verify you had full travel? :pop:
 
The throttle linkage that connects to the pump (ball-in-socket piece that snaps off and on) can get worn out. Just loosen the jam nuts and tighten/adjust until you have zero slack. Mine was pretty sloppy on my 91. Now my peddle sticks a bit so I'm thinking I need to back it off a tad.
 
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the factory ic injectors are pretty small, so hence why there is no haze at full tilt. i wouldnt see skipping a tooth with factory injectors either, seem like it would more than timing than the factory injector would really benifit with.
jon
 
4x9's are small. (stock I/C sticks). What I personally would do if I had an I/C truck, buy a set of 5x12's or 5x14's, jump a tooth on the gear then find its happy spot by rotating the pump. Take the slack out of the throttle linkage like Red sleeper mentioned, but after moving the ball on the pump to the closest hole to the AFC on the linkage. The charger wouldnt need upgraded if it's the WH1C, at least on the compressor side although a 60mm upgrade wouldnt hurt to keep things cool on a long run, especially with 5x14's. A 12cm housing on a 65mm turbine wheel will get asmatic on the high end if you aren't waste gating it. Id upgrade the turbine side a 14cm to keep quick spool up and let it breathe easier on the top. With a properly tuned AFC it will light the charger fast on the bottom, give you great power up top and in the mid range with little to no smoke if you set the star wheel and spring right. That should take care of even an H&S'd 6.4 stroker.

EDIT: if you are worried about the timing, here's what my truck looks like running 27* at idle with the dymanic advance still for 4 years. Non intercooled engine, stock 4x12's @ the 155* spray angle. 250k miles



Uploaded with ImageShack.us
 
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Not to be a stickler, but... I'm pretty sure stock IC'd injectors are 6x.009"s and the non-IC'd injectors are ~40% bigger judging by cross sectional area. No biggie, I've definately spread misinformation a time or twenty:bang

To the OP: What's your fuel pressure like? 5 psi is minimum. Even with a fresh stock LP, I could suck it down. With a low pressure piston pump, I have plenty of fuel and pulls hard even up on the top end
 
cmann250 said:
Not to be a stickler, but... I'm pretty sure stock IC'd injectors are 6x.009"s and the non-IC'd injectors are ~40% bigger judging by cross sectional area. No biggie, I've definately spread misinformation a time or twenty:bang

To the OP: What's your fuel pressure like? 5 psi is minimum. Even with a fresh stock LP, I could suck it down. With a low pressure piston pump, I have plenty of fuel and pulls hard even up on the top end
Click to expand...

thanks for the info! I just said 4x9s because i know that my non i/c sticks are 4 holes, and i know that intercooled are .009's
:thankyou2:
 
Did you take up all the slack in your throttle cable and remove your high-idle screw?

Here's a post of mine from another site about it.

Tacoclaw said:
What you actually want to do is leave your IP at the idle position, then lay on your florboard and push the top of your throttle pedal all the way back against the firewall. Then, grab the cable and pull it just enough to get the slack out of it. Find something that long that the end of the cable will fit through, pop that plastic stopper off and put whatever you're using on. Then, have someone hold the IP at WOT so you can get the stopper back on and that's it.

Here's mine:

6e9820ae.jpg


It's a 1 1/2" long piece of 1/8" water pipe. I cut it down it's length and squeezed it into the hole on the pedal some, then put a piece of truck airbrake hose in it to keep it from chafing up the cable.

Seriously, that's a lot of slack.
Click to expand...
 
cmann250 said:
Not to be a stickler, but... I'm pretty sure stock IC'd injectors are 6x.009"s and the non-IC'd injectors are ~40% bigger judging by cross sectional area. No biggie, I've definately spread misinformation a time or twenty:bang

To the OP: What's your fuel pressure like? 5 psi is minimum. Even with a fresh stock LP, I could suck it down. With a low pressure piston pump, I have plenty of fuel and pulls hard even up on the top end
Click to expand...

Stock non/ic are a 4x13.
 
Actually, here's the whole thread from 1stgen on free mods.

Zero Buck Mods

There's a few other things there you can do to help your truck out.
 
Taco

link needs fixed

ZeroBuckMods



fast fingers don't always work..........................lol
.
 
Sorry guys, I haven't been on here for a while, but I put the timing to the head and it seemed to help a little. Yes I stock Intercooled inj.
 
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