6.5L IP+ATT

[6.5L]

I own a 1993 Chevy K3500 SRW regular cab with a DB2-4911 IP and a NV4500. I have the IP turned up a quarter turn, a home made wastegate controller set at 13psi, AFE Stage II intake, 4 inch turbo back with a 3 inch downpipe, pyro and boost gauges. I am about to invest in a ATT. Right now under WOT I run a light haze which means I am cleaning up probably 95% of the fuel. I think with the increased airflow from the ATT I am thinking if it starts running completly clean about turning up the fuel another 1/8 turn to compensate for the extra airflow to create more power. Does anyone recommend this or has anybody done this? Just looking for some creative critisism. Any pointers or help would be sweet. Any please nobody tell me to relocate my PMD. It's a mechanical motor and I seem to get the answer a lot on forum sites haha

 

[Slim Shady]

I own a 1993 Chevy K3500 SRW regular cab with a DB2-4911 IP and a NV4500. I have the IP turned up a quarter turn, a home made wastegate controller set at 13psi, AFE Stage II intake, 4 inch turbo back with a 3 inch downpipe, pyro and boost gauges. I am about to invest in a ATT. Right now under WOT I run a light haze which means I am cleaning up probably 95% of the fuel. I think with the increased airflow from the ATT I am thinking if it starts running completly clean about turning up the fuel another 1/8 turn to compensate for the extra airflow to create more power. Does anyone recommend this or has anybody done this? Just looking for some creative critisism. Any pointers or help would be sweet. Any please nobody tell me to relocate my PMD. It's a mechanical motor and I seem to get the answer a lot on forum sites haha

The thing about turning up mechanical pumps is that you up the fuel rate through the entire rpm range not just at the top end. So more than likely right off of idle through the lower rpm loaded you may smoke some or you may not, A lot depends on your setup. You can turn the pump back until you don't smoke this is the most efficient method. Black smoke is wasted fuel and at today's price, well that is my two cents on that. I have worked on and rebuilt more DB2 pumps than I care to talk about, there are adjustments to the advance arm, fuel transfer pump pressure (case pressure) that you can do to get more advance which will help you burn the extra fuel to a point.

 

[WarWagon]

Your light haze can also be a touch too much timing. I would recheck the cold advance and make sure it is kicking off. Did you advance the pump for timing chain wear? Timing and fuel are all variables that can change your EGT's and visible smoke. So are precups...

Your pump may or may not have a 1/8 turn left in it before the screw bottoms. I have run mine at 1/2 turn and it smoked too much for the 1993 GMX turbo. My next pump bottomed out at 1/3 turn. With the A-Team I suspect you could bottom the screw. Simply because of the amount of smoke I can put down before the A-Team spools and then clears completely up with a DS4.

I have always wanted to try an A-Team loaded on my 1993.

I guess the A-Team will get rid of the choked engine feel over 2500 RPM. Others tell me the DB2 may be defueling in that RPM as it approaches the RPM redline set point.

I would think about how you use the truck before swapping turbo's. Also consider the DS4's put out more fuel than the DB2 can so you may not get enough fuel for the A-Team. However, if this is the case you can return the A-Team. Stock programs work well with the A-Team so you should be fine at the DB2's limits - but you will be leaving some capabilities on the table.

You will notice that A-Team is not as snappy off the line as the small GM turbo, but, it doesn't choke at higher engine RPM's.

Oh yes, about that PMD: congrats on locating that to a later model year! :thumbsup:

 

[6.5L]

I know it will smoke more at low RPM if I turn the fuel up but the main use for my truck is highway where at 65 I run about 2300-2400rpm. My GM-3 just runs out of power above 2200-2300rpm. I need highway power and I need towing power. I believe the DB2 is a great pump and I favor it's simplicty over the DS4. Not raggin on the electronic one, but I am a mechanical kid haha. Slim Shady I see your posts a lot for the ATT. I swear I have read every post about it I can find and you seem to be a crucial part of it lol I don't know if you have any specs on it Slim Shady but when I can manage to afford the ATT, which will probably be about half way through April when I get my first paycheck from the Forest Service, I can let you know how it performs with a 4911. Thank you both for the input. I will will just have to see how it performs when it gets here. Slim Shady I will be happy to send you/post install and completion pics and comments about the performance of it when I get it and get it broke in nice. If you havn't done anything with the DB2-4911 and the ATT and have any idea's I can try them out if possible. and I also don't think the motor is de-fueling. It pulls hard all the way up to 4000rpm and she has accidently touched 4200rpm once but she pulled hard to it, although I never try to take it past 3. I would like to keep this good pull while maintaining fuel mileage. I dont belive at all the GM-3 is the turbo for my truck. I think the DB2 will be a perfect canidate for a ATT in my opinion.

 

[WarWagon]

Sounds like the A-Team would work well for your use.

Keep us informed if you do go with an ATT as you would be the first with a DB2. Conformation of the higher RPM power would be great. (I get lots of high RPM power on my burb, but, the fuel systems are different enough to warrant a test.)

~2200 RPM is the peak torque of the engine even with an auto. I have noticed this with my foot on the floor with a trailer on hills - slows down to that RPM and will hold there. Best MPG is there as well. I figure a less restrictive turbo would help this MPG/power band. I already have the fender snorkel gone, 3" down pipe, and 4" exhaust.

You can watch turbo boost to see any loss of fuel at higher RPM's. I had to back my Turbo Master off after I replaced a weak lift pump.

Something to be said for the DB2 being all mechanical.

 

[6.5L]

I will definately keep you and Slim informed if you guys want. My injection pump runs strong. I know before I made my homemade TurboMaster and just had my wastegate wired shut, I could hit 20psi by 3500rpm. Surprisingly the motor and headgasket are intact and I managed to hit 20psi unloaded. just truck on flat ground. and my truck with me in it and a full tank of diesel weighs in at around 6100lbs. Relative featherweight for a diesel in my opinion. I did notice that nobody seemed to be trying an ATT on a DB2 and I think it will be a good pump for it. It is already capable of spooling up to 17psi faster than my brother can spool his modded cummins up to 20psi so I am definatly getting fuel I think haha. Time will only tell. My lift pump also kept going out so I just bypassed by whole OPS because I was tired of it and now it runs off of a relay that I can turn on and off. I also bypassed by glowplug controller with a relay and I can keep my glowplugs on as long as I keep holding the button in lol and I already upgraded to the good plugs. I think they were like 60G's or something. I can't remember, it was last year, but I kept them on for 25seconds and they work fine. She fires right up in the winter haha Back to subject though, I am just waiting on money. I am just about to finish up my 2nd year of college and start my summer job so the money should be coming in soon. This whole truck was built on a budget and I have a dyno up at G&J diesel in Billings Montana. I live in Cody Wyoming so it is only a hour and half of a pretty drive. After the ATT is on I plan on throwing her on G&J's dyno. I suspect they will laugh but right now I am aiming for at least 200rwhp and between 325 and 350ft.lbs. Who knows though lol I will keep you guys posted on the results. It will be interesting to the results of a DB2 manual transmission and a ATT. I think it will make a healthy combination

 

[Slim Shady]

OK just to make it clear I don't want someone to buy a turbo just to try out, that is not good for anyone, the price would have to go up drastically for me to be able to afford that.

Now there are a few mechanical pumped trucks with the ATT turbo and they are running fine. Big thing is the exhaust, and they do not generally smoke any more than the electronic pump if set up right. The mechanical pump is a fine piece of equipment, just not as refined when it comes to fuel metering.

So there shouldn't be any issues.

 

[6.5L]

I am not going to buy the turbo "just to try it out". I plan on using it how it was designed. i was simply saying if there was anything anybody had ideas for on a mechanicaly equipped truck. I don't hardly hear anything about any mechanicly equipped trucks since they only made them for two years and everything else was the DS4. I feel that the DB2 equipped trucks aren't given enough credit.

 

[buddy]

Some guys aspire to getting the DB2-4911 over their PMD and electronically controlled DS4. I like programming them, but I have a flow sheet on a modified DB2 that got some real respectable fuel output numbers, just that it dies past 3500rpm, so if youre not going for a land speed record its a really good pump.

 

[6.5L]

I enjoy the simplicity of the DB2 pump. It has always been reliable for me. and I don't need to pull past 3500rpm anyways. It seems even if I could, I don't think my stock cam in the truck is optimized for power past 3500rpm. Plus I am always sketched in any vehicle going past redline. The only time it has gone beyond 3500rpm was when I was racing somebody haha I had to blow the doors off some neon. I couldn't let it beat me haha plus I was curious how my truck would perform pushed all out. it was pretty respectable to be able to beat a neon haha in my opinion. I don't need an all out pump like the DS4. It would be nice for the ability for more fuel but I like being able to switch all my fuel settings for free. being in college drains the funds haha I think the DB2 is very capable of being competitive with the DS4. I think it would be nice as I said earlier if I could lay down at least 200rwhp. I don't think it will with all my mods but I guess it would give me a nice goal for a reliable powerful truck that also has longevity. I did loose some mileage though when I turned the fuel up. Anybody else experience this? I was getting 22mpg with the fuel screw set at stock and now I am down to 17-18mpg highway. That is another big reason I want to purchase the ATT. I think it would help a great deal. That's just my theory though. I also may end up turning it back down a little bit. It all depends on how the ATT performs on my truck. I will just have to see. I already have the exhaust for it. and earlier the timing issue was brought up. My cold advance works just fine. The pump is advanced about 4-5 degree's I think. I can't really recall how much I set it forward. I will have to go back and check. Would retarding my pump slightly, maybe back towards center 1 degree or 2 help my smoking issue. Because maybe it is just because I have a manual but she smokes a lot when just regularly accelerating down the street with a light right foot. Any advice would be great. I always enjoy hearing about the 6.5L

 

[WarWagon]

Slim, I doubt anyone would return an A-Team after using it with a 4" exhaust. I did not know and can't find any info on anyone using it on a DB2 so that is news to me. They need to post up...

As far as MPG, turning up the turbo and IP screw with a full load kept my MPG the same just got me more MPH. As you are unloaded you may want to back the boost down as some members found MPG gains by doing this with a TM. You are getting boost by backpressure vs. heat with the small GM turbo at low load. A-Team eliminates this issue.

Retarding the timing will cut some smoke. Just knowing if it is fuel or timing is the trick.

 

[Slim Shady]

I am not going to buy the turbo "just to try it out". I plan on using it how it was designed. i was simply saying if there was anything anybody had ideas for on a mechanicaly equipped truck. I don't hardly hear anything about any mechanicly equipped trucks since they only made them for two years and everything else was the DS4. I feel that the DB2 equipped trucks aren't given enough credit.

Nothing meant by my comment towards you just a general comment. I have had good luck with a DB2 and like them. Like I said I gave at least four guys running 93 and a 89 blazer with a DB2 pump and they run great.

 

[Slim Shady]

I enjoy the simplicity of the DB2 pump. It has always been reliable for me. and I don't need to pull past 3500rpm anyways. It seems even if I could, I don't think my stock cam in the truck is optimized for power past 3500rpm. Plus I am always sketched in any vehicle going past redline. The only time it has gone beyond 3500rpm was when I was racing somebody haha I had to blow the doors off some neon. I couldn't let it beat me haha plus I was curious how my truck would perform pushed all out. it was pretty respectable to be able to beat a neon haha in my opinion. I don't need an all out pump like the DS4. It would be nice for the ability for more fuel but I like being able to switch all my fuel settings for free. being in college drains the funds haha I think the DB2 is very capable of being competitive with the DS4. I think it would be nice as I said earlier if I could lay down at least 200rwhp. I don't think it will with all my mods but I guess it would give me a nice goal for a reliable powerful truck that also has longevity. I did loose some mileage though when I turned the fuel up. Anybody else experience this? I was getting 22mpg with the fuel screw set at stock and now I am down to 17-18mpg highway. That is another big reason I want to purchase the ATT. I think it would help a great deal. That's just my theory though. I also may end up turning it back down a little bit. It all depends on how the ATT performs on my truck. I will just have to see. I already have the exhaust for it. and earlier the timing issue was brought up. My cold advance works just fine. The pump is advanced about 4-5 degree's I think. I can't really recall how much I set it forward. I will have to go back and check. Would retarding my pump slightly, maybe back towards center 1 degree or 2 help my smoking issue. Because maybe it is just because I have a manual but she smokes a lot when just regularly accelerating down the street with a light right foot. Any advice would be great. I always enjoy hearing about the 6.5L

Adjusting the timing back would clear up your smoke a little. You may want to adjust your side advance arm to where the ramp just touches the roller on the advance arm if you want to remove the smoke. For performance you move the ramp away from the roller on the arm (at idle).

Also if you want to advance your timing through the whole range you can adjust the transfer pump pressure through the inlet of your fuel pump. There is an allen screw in the center of the fuel inlet that adjust the transfer pump pressure setting. I wouldn't adjust it more than a quarter to a half turn and see how it performs. Disclaimer, Do this at your own risk,

 

[6.5L]

I am not looking for power throughout the RPM range as I have plent of get up and go above about 2000rpm. I was just looking to maybe clear up some of the smoking issue at lower RPM when I am not heavy in the throttle. Slim, I hate to be a burden, but could you explain the details of the side advance arm, where it is, and the pro's and con's of that since you have much more experience with the pump than me haha. I don't think I will touch the transfer pump pressure because i don't need that advanced in the upper range, it runs fine then. If I can't and simply need to retard the pump a degree or two that's fine, it's not a huge deal. I was just wondering. Your advice would be appriciated. And like WarWagon commented, I havn't heard anything about any ATT equipped DB2 trucks in the forums. That's why I was asking earlier. If it's not a trouble I would like to hear some details you may have heard back from the DB2 equipped trucks with the ATT. If you don't got the time or something don't worry about it. Like I said earlier, it's not a huge deal. I am just looking for the good balance of everything haha

 

[WarWagon]

What RPM is it smoking at, how heavy of smoke, what is the EGT reading, and what color smoke? Light throttle smoke does not sound like too much fuel. Lugging maybe?

 

[6.5L]

It basicly has a haze at almost any RPM when I am accelerating. If I am really really light on the throttle it doesn't, but I have to be way out of the throttle to not have it smoke. If I am normally accelerating it smokes a light haze kinda throughout the rpm range, even when I spool turbo to like 15psi there is a bit of smoke always coming out. I never lug the engine down. I hate doing that. I think it may have more to do with the timing. I never see 6.5L smoke throughout the RPM range unloaded like mine does. I can always see it. it bothers me. I am gonna try retarding the pump a little bit to see if that helps any. I am not too familiar with advancing/retarding but you guys seem to say it may help so I am open to anything at this point. The smoke isn't really heavy but just a haze. The smoke is black, definately. I can see it. and my EGT's depend on how heavy I am into it. Under normal acceleration it never goes above about 350* (pyro right after turbine at the top of the downpipe, so add 300* and I am seeing about 650* piston temp). That should be enough to burn the fuel right? I am not 100% sure. On highway at cruise control it doesn't smoke but if I even look at the throttle and want to accelerate 1mph it starts hazing. Even with the turbo sitting about 3-4psi. It is weird. Do you guys think my timing may be too far advanced? Under WOT in Overdrive I can keep boost at about 13-15psi and it never gets above 700*, or 1000* piston temp, depending on how you want to read it. I don't know if that info helps but you asked about EGT's. And even at 15psi right before the wastegate catches up, I still have a fairly good amount of soot being throw out. Should I retard the pump and see what happens? You guys are really helping this and I appriciate it. Sorry I have a lot of questions,but I just want to get it figured out. Any advice is welcome

 

[tanman_2006]

My 93 does the exact same thing, I can put out a thick cloud at take off with it floored and it hazes through the whole RPM range after that, even at partial throttle. If you have the original injectors you might have some bad ones not spraying fuel right. My IP is turned up ~3/8's of a turn, just past 1/4 I dont have an EGT probe in yet and see ~20psi at times. I will be changing my set up soon to a holset, penninsular intake, walbro, 4in DP, and getting all of my gauges hooked up.

 

[6.5L]

When you get that done,let me know how it works. keep me posted haha

 

[deejaaa]

I will definitely ....................... make a healthy combination

make sure you get a baseline pull on the dyno before you use the ATT. there is nothing worse than spending time/money on a project and not know where the problem lies if there is one.
one thing to consider is your timing chain. at 150,000, mine had stretched 1/4 inch, throwing my engine timing off enough to smoke ALL the time. mileage went way down also. mine was white though.
i plan on running an ATT on the 93 as soon as i get some things lined out. i will post info on the install. while the old turbo is off, i plan on changing 3 of the hard-to-get-to injectors for another set i have.

 

[6.5L]

STATUS UPDATE: Took it over to my dads diesel shop and retarded the timing half of what it was. Changed a world of difference. Smoke went down at least 60% and now only smokes when I get into it pretty hard. Somehow it improved low end torque. No exageration, my low end torque feels like 60-70ft lbs was added down low. She now pulls herself into gear very nicely. Truck runs 100% smoother. Revs very very nice and smooth. I think the pump was just way too far advanced.