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First towing trip with my new engine!

Discussion in '1982-Present GM Diesel' started by arveetek, Jun 23, 2005.

  1. arveetek

    arveetek 1/2 ton status

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    I can sum up the experience in one word: WOW! :D

    I can't beleive how much more grunt and torque my truck has now!

    Last Friday, my wife and I left our home with our 29' Alpenlite 5th wheel (I know many of you are familiar with our rig). My parents took their rig as well, and so we convoyed to Ft. Worth, Texas.

    There aren't a whole lot of hills between here and there, but I never found a single hill where I had trouble maintaing speed up the incline. The biggest hills we encountered were on the way back, through the Arbuckle mountains of central Oklahoma. I wouldn't really call them mountains, but I was able to maintain 65 mph up the hill all the way to the top.

    In fact, about 50% of the trip I was able to tow the trailer in overdrive at 70 mph. I couldn't believe it. I've never been able to tow in overdrive before, unless it was extremely flat with no head winds. But now I have enough extra torque that I can pull up some small hills in overdrive without shifting down to third.

    I averaged 11 mpg. That's better than I expected! The new engine has so much more torque and power, that it didn't take much throttle to keep the load moving, so I actually ended up using less fuel.

    On this trip, I rarely had to give it full throttle. 1/2 to 3/4 throttle kept me moving and accelerating at a great pace. That usually kept me in the 7 to 11 psi boost range. When I really needed the power, I could mash the pedal and climb hills at 15 to 16 psi, with EGT's right at 1050. The only time I saw EGT's climb higher was when I was lugging in overdrive. I had to keep an eye on it then. There wasn't enough boost at that low of an rpm to keep the EGT's down. If they started climbing, I simply just pulled it down into 3rd, and then the boost jumped up and the EGT's fell, all at the same throttle position. It's really cool to see how boost effects EGT's. I could see 7 psi and 1100 degrees at 65 mph in OD, then pull it down into third and see 10 psi and 900 degrees at 65 mph, all at the same throttle position. It just goes to show how engine rpm, boost, and EGT's are all related to each other.

    My dad was pulling his 10,000 lb. 5th wheel with a 95 Ford Power Stroke 7.3L diesel, with the 5 speed. My trailer weighs around 8,000 lbs. Even though his truck is chipped, I was able to come up behind him on the hills. I even passed him once just to show off! I know his load was heavier, but I still expected the Power Stroke to outpull me. But he couldn't. We were pretty well evenly matched.

    I wish I had another gear, though. Third left me with plenty of power, but really high rpm at 70 mph. 4th is too high, with not enough power and too low of rpm. Something in between would have been perfect.

    The only problem I had was engine cooling. I really had to watch the guage when pulling hard up hills. It would climb pretty fast. I didn't figure out until we nearly got home that it was mostly due to the fan clutch. It wouldn't engage the fan until the engine rpm came down low, then it would kick in. The temp. guage would be nearing red, but the fan wouldn't kick in unless I slowed the engine down. Once the fan kicked in, the temp would come back down. The last hour of the trip home, I popped the spring loose on the clutch to keep the fan engaged all the time. From then on, I ran cool as a cucumber. The only problem with that is it's rather noisy and it robs a bit of power.

    Upgrading the cooling system to a dual-t/stat setup w/high-flow pump ought to be done. A better fan clutch is needed as well. An electric clutch would be ideal, so I could control it from the cab. For now, I'll just pop the fan spring when I'm towing, and then put it back in place when I'm not.

    Before the turbo and before the rebuild, my n/a 6.2L would pull way down on two of the local hills and crest the top at 45-50 mph. I would have to downshift into 2nd to get there, with the engine rpm hitting near the governor. Now, I can pull up the same hills at 65 mph in 3rd, actually gaining speed by the time I reach the top. I never had to downshift into 2nd on any hill I encountered. Plus, I have so much more torque, I don't have to wind the engine up nearly as much as before. It just pulls and pulls and pulls no matter what gear you're in.

    I would say that I have probably doubled the power of this engine over the stock n/a form. I am very pleased with the power and performance, and once I get the cooling issues addressed, I'll have a very good performing truck that I wouldn't mind crossing the country in, with my RV in tow.

    So, to all those who say the 6.2L is a gutless, worthless engine....well, perhaps a stock n/a with stock gearing, etc. can be pretty gutless, but I guarantee you, they can be built to perform!

    Casey
     
  2. FWP

    FWP CRS

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    Ok, what did I miss? How are you getting 15 psi boost, without blowing out the head gaskets or other mayhem? Somebody clue me in please :)
     
  3. arveetek

    arveetek 1/2 ton status

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    I believe the stock 6.2L can handle up to 15 psi before causing any problems, but I did go the extra mile to lower the compression ratio to around 19.75:1 from the stock 21.5:1. I also had the pistons ceramic-coated. This ought to allow the engine to run easier and keep from blowing the head gaskets.

    I ran this engine for almost a full year at around 14 psi max on stock pistons, heads, and gaskets with no problems. Now I've seen the boost spike past 17 psi after the rebuild.

    To make as much boost as I'm seeing, I'm using 6.5L turbo pump and injectors, a unique turbocharger, lowered compression, and 4" exhaust. The "stock" Banks turbocharger has a 1.00 exhaust housing, while the upgraded Banks IH turbo has a .84 housing, I believe. My Rotomaster turbo has a.69 exhaust housing. Don't ask me to explain these numbers, as I haven't fully grasped the concept yet, but I can tell you my turbo spools up quick and still builds a lot of boost at high rpm.

    Casey
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Is that number a ratio of some description?

    When are you building a turbo 6.2 for me Casey? :)

    Rene
     
  5. FWP

    FWP CRS

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    Good info, thanks! From what I've read, I was under the impression that 10 psi was nearing the limit for boost on the 6.2 heads. I would say , with your info, that is incorrect.

    It would be very valuable to have some dyno numbers, I bet there would be a few of us that would contribute to the cost of a dyno run for ya ;) . Wouldn't it be cool to find out you can mod a 6.2 and get the same results as a 12V bombed cummins :cool1:
     
  6. joez

    joez 1/2 ton status

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    Id be willing to chip in on a dyno run, just to get some numbers, even though it will be a far cry from a bombed 6bt.
     
  7. arveetek

    arveetek 1/2 ton status

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    I would love to run this truck on a dyno. I'm really curious to see what I'm putting out now. I would estimate I'm over the 200 horse mark, hopefully close to 250 hp. I'm not sure on torque. I agree that I won't be matching a bombed 5.9L, but I bet I'm not too far off the mark.

    I don't know of any dynos in my area, but I'll have to scout around....

    Rene,

    You supply, the dough, I'll supply the engine! :D

    Why not come down to Missouri, and we'll build another 6.35L turbo diesel? :D

    Casey
     
  8. rich

    rich 1/2 ton status

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    I am VERY interested in your cooling issues. My stock NA 6.2L in my 1990 Burb does the same thing - it has a new rad, new fan clutch, B&M oil cooler, and B&M trans cooler, so it runs nice and cool during normal driving. But when towing, whenever I have to downshift, the temp climbs fast. I bet it is like you said - the fan clutch.

    It suprised me when towing that when I lugged the engine the temp stayed down, but when I downshifted the temp would climb (even though it should be easier work for the engine in the lower gear). The fan clutch makes sense - when the engine is spinning faster, the clutch is disengaging.

    I'll check my fan and see if I can easily mess with the spring like you did. If that helps my cooling issues, that would be great. Is it just a spring you can pop off the front of the fan or something?

    If anyone has a better/permanent solution than keeping the fan engaged all the time when towing, I'd like to investigate!

    Thanks!
    Richard
     
  9. 86dieselburb

    86dieselburb 1/2 ton status

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    I'm betting the rise in temp has to do with the added coolers not allowing enough flow the radiator needs to cool under loads, such as towing. The reason I say this is my 6.2 sub, the temp never budged when climbing or towing. Recently I had to replace my tranny and in doing that I added a B&M tranny cooler. Now the motor gets alot hotter when climbing hills or towing. Before the motor never budged past 190* lately it gets close to 210*
     
  10. diesel4me

    diesel4me 1 ton status Premium Member

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    here's how..

    I had too "lock" my fan clutch in while driving with my plow blade on my 74 K20,or it would boil over in 5-10 miles of driving at highway speeds..( my 82 K20 Diesel has never overheated,and I havent had to "lock" the clutch on that yet!--must be due to the HUGE radiator!?..) :confused:

    All you have to do is pry the end of the "snail" spring on the face of the fan clutch out of its little holder,rotate it 180 degrees,and clip it back into the holder...and its in the "locked" position!..I was able to drive at 65 for as far as I desired with it locked in..it did rob a lot of power and sounded like a hoover vacuum cleaner though!.

    ..They used to sell "fan clutch eliminators",that were nothing more than an aluminum block with the correct bolt holes to bolt to the water pump,and the blade used on a clutch fan..havent seen them lately,but I think Valley brand of towing products still does...it kinda sucks having it "direct drive" all the time though--it does reduce power and mileage some,and IS pretty noisy.. :crazy:
     
  11. arveetek

    arveetek 1/2 ton status

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    Yep, that's my same experience. Lugging the engine it will never get hot, but pull it down a gear, and the rpms jump up, the EGT's fall, the boost climbs, but the engine coolant temperature goes up. Of course, forcing air into the engine also creates heat from the compression of the air. That's where an intercooler would help a lot, to cool the compressed air. Just feel the discharge line of an air compressor when it's filling up a tank, and you'll know what I mean.

    I really don't think the oil coolers in front of the radiator should make much difference...the tranny cooler didn't move, it's where it's always been, but I did relocate the engine oil cooler in front. Before, it was plumbed directly into the radiator, so it was dumping the heat into the water, instead of into the air in front of the radiator. Really, when you think about it, it's amazing the radiators work at all, with two coolers, and an a/c condensor all dumping hot air into the radiator. That's why most aftermarket intercoolers for the GM trucks are located somewhere besides in front of the radiator. The GM diesels like to run hot as it is.

    Popping the spring loose on the fan is easy. There's a tab on the spring that fits into a slot. Pop the spring's tab out of the slot, and that's it. It will stay engaged.

    Casey
     
  12. Grieby54

    Grieby54 1/2 ton status

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    I've never run a diesel before in my life, so I don't know if there's any difference. But to get rid of your cooling issue... buy an electrice fan, that way it'll always be on (or you can make it switch activated) and it won't be robbing you of any power...
     

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