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Junior Member
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46 Posts
Discussion Starter #1
Hey everyone,
Last summer i installed a universal pacbrake exhaust brake in my 91 IH 4700. It works well at 3k RPM, but strength falls off fast. I have it set to 36-38 psi max backpressure now, but I know on the 5.9 cummins it can be 60 with upgraded valve springs. By any chance do those work for this engine? The trouble is, it not very efficient over a wider rpm range. Thanks.
Mike
 

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Super Moderator
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3,190 Posts
I'm not sure if they are the same spring. You can call Hypermax, and get the ones they recommend.
 

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'Ol Builder guy
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7,051 Posts
Another thing to consider is I would bet the NGD series DT360 (if they made one) probably had stiffer valve springs because I'm pretty sure the NGD 466 & 530 had an available exhaust brake. One could probably bet that the DT360 did as well.

How is the ex brake working for you?

I really want one, but from what I hear the backpressure has to be set too low to really be effective. Set it too high and you've got damage.

I also feared the butterfly valve would push my EGT's up ~100 degrees because of downpipe blockage.

With all the DT466/360/530's out there, you'd think Pacbrake and the rest would offer a valve spring kit to get them set up correctly so an exhaust brake would be effective.

Then they could sell thousands more exhaust brakes!
 

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Junior Member
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46 Posts
Discussion Starter #4
Like I said, it works well if your are revved. I came down a pretty good grade, dont know %, towing a 26 ft. box truck around 18K, and it held decent. Its just when you slow to 2500 rpm it looses efficiency and doesn't work as well. My temps didnt raise much, i can hit 1300 loaded if i keep my foot in it for 20 sec up a hill, running about 28psi. Also, what is a NGD motor? It would just be sweet if at 3K it had 60 psi, and 2K it had 30. Ill call hypermax today.
 

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Member
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391 Posts
NGD= Next Generation Diesel. I don't recall exactly when the change occurred.
 

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'Ol Builder guy
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~'95-'96 NGD's hit the scene.

You can get the stiffer springs, but then you gotta dig into the valve cover.

Might be a good thing to do when you're up against a valve job. I think you're supposed to check 'em or do every 75K.
 

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Super Moderator
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The NGD on the 408/466/530 started in 93. The 360 ended in 93, and didnt get the NGD treatment.
 

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Junior Member
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Discussion Starter #8
Well, hypermax doesnt necessarily have a spring for my application, but they do have a double spring which they use on the race motors spinning 5K. I called my local dealer and I can get 6 stock springs for the 360 for $35, which I then could measure seat and lift pressures at the local machine shop. This would also let me get exact measurements and possibly compare them to other springs. I dont know why others have not tried this, i think the 360 is a good engine, when turned up of course. All i have to do now is still get rid of my preboost smoke issue.
 

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'Ol Builder guy
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7,051 Posts
The NGD on the 408/466/530 started in 93. The 360 ended in 93, and didnt get the NGD treatment.
I've seen 94 IH DT's that were not NGDs!!

I've also seen 2000 IH's with MT series Allison transmissions nad '99 IH's with more advanced MD series electronic Allisons.

I went to Florida to look at a 2001 GMC 4x4 with a MT653 in it. MD's were in trucks by then.

Trucks are weird like that.
 

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'Ol Builder guy
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7,051 Posts
Well, hypermax doesnt necessarily have a spring for my application, but they do have a double spring which they use on the race motors spinning 5K. I called my local dealer and I can get 6 stock springs for the 360 for $35, which I then could measure seat and lift pressures at the local machine shop. This would also let me get exact measurements and possibly compare them to other springs. I dont know why others have not tried this, i think the 360 is a good engine, when turned up of course. All i have to do now is still get rid of my preboost smoke issue.
There's a degree of difficulty to modifying DT's like you would a 7.3, a DMAX, a 5.9 Cummins in a pickup. Usually there's a "bottleneck" in every series of DTs. Mine is the pump. The plungers & barrels are just too small for anything more than minor streetable modification-maybe 30-50 more HP if you're lucky.

I would love to have 300 SAFE low-EGT, workable HP so I can still safely haul a 10 ton load. I don't want to race my truck or limit it to an empty truck running 1300* EGT on a drag strip.

Hypermax (Jeff or Ron) will tell you straight-up, when it comes to DTs, they are in the business of 1000-2500 HP DT's for tractor pulling. They offer nothing much more than their condolences to you when you want "streetable/useable" milder HP levels. They guys at Hypermax are the best, but they just don't have much other than some advice.

I wish it were different, but I've spoke with Jeff more than 10 times about this very subject.

If you have a pre-boost smoke issue, I would think turning the star (smoke) screw back a few turns might help, but I'm not sure which pump you have.

Let me know what you come up with on stiffer valve springs. I'd love some extra braking power from a PAC brake. I bet a lot of older DT owners would love more, too. I'm close to needing a valve adjustment, so it would be a great time to do it.
 

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Junior Member
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Discussion Starter #11
I got the stock springs in from IH. But im going on vacation for a week, so i wont be checking. Im concerned about actually changing the springs in the truck. Are there any tools i can use to change them? I have seen the tool for the 5.9 cummins, maybe it would also work on this motor? Ill be in touch with what I come up with.
 

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Junior Member
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Discussion Starter #12
Well, ive given up on my quest. Other than custom springs, it seems there is nothing that makes a worthwhile change. I found a set of comp cam springs that have pretty much the exact dimensions, but with a 450 lb. 1" compression rating, while the new stockers were about 215 lbs. The machinist was concerned about wiping the cam lobes with the others. We also tried a .060" shim under the spring, and it only increased seat pressure about 10 lbs. So, since it would be alot of work to even change them, its not a big enough improvement to warrant the time. Oh well.
 

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Super Moderator
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That was a great effort though. I would think 450 pounds of open pressure would be way too much too. That sux
 

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'Ol Builder guy
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There's just not enough mods for mild power increases on DT diesels. It's too bad b/c they're so popular you'd think whoever would offer them would make lots of $$
 
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