Engine/Transmission (1998.5 - 2002) Changed my 275's for DD2's today and have some questions.

[TPlasek]

This evening, I changed out my 275 injectors for a set of DD2's. It sure was easier to change the injectors since I had done it before.



First impressions, after I got the air to bleed out of the lines, the truck's idle sound, sounds different. No miss, just different. It rattles more now then with the 275's.



Next the test drive... I had an EZ before and after the install. Empty, I really couldn't tell the difference between the 275's and these DD2's. I went from 29 pounds of boost to 32 after the install. So it seems there is more fuel there. The EGT doesn't rise any quicker then with the 275's and there doesn't seem to be any smoke difference (it was at night so maybe it was more smoke then I thought) Maybe a load is required to tell the difference. I thought I was in tune with my truck and would notice the difference no matter how small it may be.

I was hoping for a more drastic change, or at least the same change I got from stock to 275's.



The next thing I noticed is my truck has always idled about 50 rpms higher while you are rolling to a stop in neutral. After I would get below 5 mph, you could hear the truck idle down and watch the tach drop about 50 rpms. to about 850 Rpms. This happened with my stock injectors and with the 275's. My truck no longer does this. It just drops to 850 rpm, no matter what speed you are at, and stays there all the way to stop. I find this strange.



Is there something I should check to see if there are any installation errors? I have no fuel leaks at the injector lines to head, but what if the lines were leaking where they seal with the injector body itself. I would think I would get a miss. I don't think I have a miss, just a different idle sound.



I am thinking about loosening everything up tomorrow, and resnugging everything down. Maybe I was just expecting too much out of DD2's, but the idle speed has me baffled. I wouldn't think the idle RPM would be determined by injector size.



Any help, comments, or past experiences would be greatly appreciated.

 

[Big White Beast]

Don't know about the idle........

I imagine the injectors could make somewhat of a difference.



As far as power goes. 275's are the equivalent of DD1's I believe. That would only be a 20 HP jump to DD2's. On a dyno you'd probably tell the difference more so than by seat of the pants.



I went from stock to DD2's (Already had an EZ) on the 01 and wasn't impressed at first. The main difference I saw was lots more smoke. Acceleration felt a little better but not worth the money. Remember the 01 is a heavy truck. When they really kicked in was in the power band. That's when the HP peaks and you feel it the most.



On the light weight 2500's I imagine you'd be flying by then and not notice it as much either. Hook up a trailer and go climb a hill. I bet the difference will be more apparent then.



Garrett

 

[csevers]

I also started with 275's then went to dd2's and I sure as hell could tell the difference between 275's and the dd2's I don't even use the comp any on daily driving now. The only thing I have noticed is the pump sounds different when running down the road with some load on the engine and easing out of it , it sound like the timing is changing drasticly, this doesn't happen all the time can't link it to any thing else.



Craig

 

[HVAC]

DDIII's

An increase of 3 pounds in boost is considered by some to equate to a increase in horsepower of 30 rwhp. That sounds about right. Also, some people are of the opinion that increases in the 20 hp range are tool minimal to detect via seat of the pants. This is where the dyno comes into play.



I almost never recommend less then the III's to my clients.

 

[Smokewagon]

Hey HVAC!



Is there a feel it in the "Seat of your Pants" between DD2's and DD3's? I have a buddy that wants a set of 2's, and I'm thinking of selling him mine at a reduced price and buying a new set of 3's. I also believe that there is a "more distinctive" noise coming from the 44 with the 2's vs stock. Don't get me wrong here, I absolutely love my 2's, just wanting to know if I could tell the difference and if it was worth the money? Also if there is a difference is it in the midrange and more smoke? I like smoke



Dave

 

[TPlasek]

I found out why I thought the DD2's didn't perform better. I had the heat on in the truck. Even though I had it on the floor only vents, my switch is very sensitive and it thought I was in the next spot. I was running with the A/C compressor on.



I can now tell there is an improvement over the 275's. About what I expected.



I still don't have my 50rpm "high idle" feature back. It still wants to go strait to 850RPMs.



Also, I still don't like the way the truck sounds. It may run better, but the idle rattle has increased as well as the "groaning" sounds the truck makes under WOT. For some reason it just seems stressed (maybe it is). Maybe this is what a 300 HP diesel motor is supposed to sound like. I am going to play with the injectors a few weeks and see what the mileage is with them. I have one trip planned this weekend and one the next. One will be loaded and one unloaded.



If the DD's suck much more gas then the 275's, then the gain in HP , to me, just isn't worth the extra noise or loss of fuel mileage.



I'll let you know what happens... I am glad I had the opportunity to try these famous injectors. IMHO there is just so far I want to take my daily driver, and I think I may be one step too far now. Reminds me of jetting my fourwheeler. I kept going up and up and up, and finally I got one size too far. I just went down one size and it was perfect.

 

[Snow man]

Tplasek, if the injectors sound funny or wierd there is something wrong,I have run dd1's,2's 3's and bully dog 5's and 7's. All the DD injectors run great,and none have displayed any real difference in noise. Dave,while your waiting for HVAC to reply i can tell you from my experience that the DD3's feel much stronger than the 2's. They also smoke more off boost. I love the dd3's myself. The have great power,and with a comp you can tune out most of the smoke for daily driving. I would go to the supermental injectors from the dd2s' though. They are the about the limit of a streetable injector.

 

[raf2000]

I swapped 275's for DDII's and run a DDTT (EZ) on three. I noticed a different engine sound/rate of fire coming down from about 30mph to 0. I did notice a moderate amount of power difference, probably would buy III's if I did it over but like the lack of smoke for the most part. Anyone have a good comparison of DD2 vs DD3 with auto and an EZ?

 

[RO'neal]

Originally posted by raf2000

Anyone have a good comparison of DD2 vs DD3 with auto and an EZ?

How bout the same for a 5-speed?

 

[raf2000]

Actually, with regards to smoke, not true. You can over-gear (lug) the engine to produce a large cloud of smoke almost at will with a manual. With my ATS 4 setup, my truck requires just the right moisture/temperature/load combination(s) to get any good steady smoke. I love it when pulling my trailer in the cold!