CTD in a Chevy 1500 (blasphemy?!?)

[CRivero]

Greetings folks!



I've managed to fit a '91. 5 6BT (with its respective 3spd automatic transmission) in a '93 Chevy 1500 and I'm having some problems generating a significant amount of boost. I've been reading through the forums and it appears that the stock engine should generate somewhere between 14 to 18 psi of boost at WOT.



However, I have made some modifications (4" exhaust, injectors from an 8. 3L CTD, adjusted the full fuel screw, hx35 with 12cm exhaust housing, and a holley blue electric pusher pump 110 gph) and it barely does 17 psi at wot. I figured the engine was completely mechanical and that it should work without any electronic management system but I can't seem to figure out why boost numbers are so low and performance is sub-par. I also pressure tested the intercooler and replaced all the intercooler hose fittings to rule out any leaks in the system.



I'm getting plenty of fuel (steady stream of moderate black smoke at wot). Any ideas?



I wanted to get your input before I start making more adjustments to the injection pump and advance the timing. I'm going to install the pyro today and test it over the weekend.



Thanks,



Carlos

 

[dremelts]

Welcome to the TDR.



It doesn't matter what kind of truck (or other vehicle) it's in - as long as it's a Cummins



Sorry, can't help you much on the boost question. Other than to say that I think the wastegate is set to 22 or 23 psi, but if it were defective I s'pose it could be dumping at a lower psi. I've seen mine go over 20 psi when I was pulling our trailer up the long eastbound grade to the Eisenhower tunnel in 4th gear.

 

[bgilbert]

I bet those injectors from the C-series aren't designed to flow big time fuel to get much more boost?? Bill

 

[JLEONARD]

Some of the C series make nice hp stock... . the marine versions go up to 550 I think... . and that's out of an 8. 3 L so there needs to be some decent fuel volume.

 

[dpuckett]

First, how fast does it move? IN a half ton, it may not put enough load on the engine to make it work hard. That said, change your fuel & air filters, and if that still doesnt help, I'd suspect injector tips- with the stream of black smoke and lackluster performance, some of the holes could be clogged up and only flowing half fuel or so. With a H1C-12, you should be able to top 20 with no problem. When I had the 12. I had trouble keeping it under 30 . Still have trouble keeping it under 20 now. And I wonder why I get 18 mpg Check your boots, intake bolts, etc and see if anything is loose.



Beef up that front suspension- they barely suport the 350 that was stock; much less a 1000# Super B.

Daniel

 

[CGauthier]

Loollz..... thatz like putting a Harley engine in a tractor lawnmower

 

[MidwestMotorman]

Check your air filter and anything relating to airflow. Are you running a stock intercooler and the stock hoses? Any hard bends or other restrictions? Those 2. 75 gears may not get you up in the rpm band. If you have the 8. 5" ten bolt GM rear, gear change is easy. You must have a top speed of 100+ mph in that thing.

 

[phillips5]

What did you use for a air cleaner is it big enough. Put a vaccume gage between the air cleaner and turbo.

 

[Philip]

injectors from an 8. 3L CTD

The C series line of engines uses a P pump on it. This pump has higher pop pressures than a VE pump uses.



Did you have the injectors reset to lower pop pressures?

 

[CRivero]

Thanks for all the replies, gents! Yeah, I know the engine is overkill, but we all must be a bit crazy or else we wouldn't be here. You're right, the gears were installed to increase the top end to 120+. The real issue here is the 3spd auto transmission which will get replaced as soon as I blow it (any suggestions for a high hp replacement?).



I'm using a K&N air filter, replaced the intercooler hoses and clamps, and adjusted the full fuel screw. I've tested the system for leaks, but could not find any. My next move may be installing fuel pressure and transmission temp gauges to get some additional info. What should I expect for fuel pressure?



Today, I installed the pyrometer in the exhaust pipe 3 inches after the exhaust housing . I know it should be installed in the exhaust manifold, but I wanted to do a quick and dirty install just to get some readings. It registered 800*F at 15 psi boost.



I'm at a loss here guys. Don't know if there's any electrical feedback between the engine, injection pump, transmission, and some sort of engine control module that I'm missing since it's not on a dodge. I'm considering replacing the injection pump for the 7100 and getting bigger injectors but the fact that I'm generating black smoke indicates (to me atleast) that I have enough fuel just not enough O2 to burn it.



Another theory is that the transmission is not putting enough load on the engine and/or the factory TC may be slipping since there's no way to lock it up. I want to avoid the trial and error approach to solving this problem and would like some professional help (I know when I'm in over my head). Anyone know of a good shop in Florida?



Thanks again for the help.

 

[Philip]

Did you have the injectors reset to lower pop pressures

 

[RGT]

I would go ahead and bump the timing up...

 

[CRivero]

Philip, I don't know how to reset the injectors. How do I do that?



RGT, that's the next step (advance the timing). I'm need to set aside some time to do it.

 

[Philip]

To reset the pop pressures you need to take the injectors to a pump repair shop. Peirs or Schieds are just two of the dealers on this forum off the top of my head that can do this. But this is a minor procudier for a pump shop.



In this case advancing the timing is not going to help. The fuel is flowing so late in the power stroke from the higher pop pressures. The VE pump does not have enough slot on the bolts to help.

 

[steveinaz]

pump timing

i would roll the pump up towards the intake manifold about as far as it will go . i think it ended up being 15 or 17* advanced with my 93. it ran a hohellavalot better than the factory setting.

 

[Timebomb]

I have a buddy who put a 92 CTD in a 93 or so Chevy 3/4 ton. He used the chevy auto if I'm not mistaken and with my old B. D. 40 hp. injectors its up around 22 psi. He uses it to pull a super stock pulling tractor. The truck works great now that it has the CTD.

 

[Philip]

Carlos I just did a little searching here on pop pressures. It looks like the VE based injectors run around 3200 PSI on pop pressure. The P7100 based injectors run aound 3800 PSI. This extra amount of pressure is causing the engine to think it is retard on timing. How much I can't even guess.



Like I stated get the injector pop pressures reset and then see how she runs.

 

[sparks57]

I betcha $5 it's the pop-off pressure, along with the need for better tuning.

 

[CRivero]

All right. It seems like the consensus is to reset the pop pressure on the injectors and advance the timing after that. I'm gonna give that a try this week and will let you know how it goes.



Thanks again for your guidance.

 

[phillips5]

I have a portable injector pop tester. . One of those ones that you carry like a suitcase with a pump handle . You put on the kitchen table after supper and test inj. pop pressures.