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Discussion Starter #1
Talked to Cummins but it was much like talking to a shovel. Only thing I found out about my 4BT CPL 858 was that the 7mm injectors, #3912468, were "...the wrong injectors..." Well, don't know what to say as it's stamped into my engine data plate as the OEM injector.

Anybody got any application info on what series engine these injectors were used in? This engine was a FritoLay repower, 1990 mfg. date on engine. I'll be looking for a little more power and need to know what I'm starting with. Thanks!
 

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Talked to Cummins but it was much like talking to a shovel. Only thing I found out about my 4BT CPL 858 was that the 7mm injectors, #3912468, were "...the wrong injectors..." Well, don't know what to say as it's stamped into my engine data plate as the OEM injector.

Anybody got any application info on what series engine these injectors were used in? This engine was a FritoLay repower, 1990 mfg. date on engine. I'll be looking for a little more power and need to know what I'm starting with. Thanks!
Following info is from Cummins QuickServe and the Master Pump and Injector Manual. That is a Cummins injector assy # for CPL 851, book says 9mm 4 cyl. application and does not show for a 6 cyl. application as I believe you stated in a different post on this site. I could not find a thing on CPL 851, I didn't spend a bunch of time looking though. Also, Diesel Care & Performance have a good reputation, I'm just passing along info I found, take it for what it's worth.

4 cyl. CPL 858, 857 & 727 all use Cummins injector assy # 3909522. There are five 6 cyl CPL's that also use that Inj. #, Including the truck I drive.

I did notice in the Pump Manual that the 105hp engine is spec'd the same as the 120hp engine with the exception of the spill port timing. 1.00mm vs. 1.25mm, pretty good gain in HP for 1/4mm timing advance...
 

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Thanks, sdstriper! I have been in contact with Oregon Fuel Injection and after a lot of searching the fella there said that his listings do show this injector on some CPL 858 4BT's, but he didn't know power ratings. He didn't find out if they were 7mm like the Cummins rep says. They have rebuilts of this injector available exchange.

It's a problem because I want to put some new injectors in and would like to pick up some power while I'm at it. The same engine CPL data plate that lists my injectors says 105HP. That makes them roughly equivalent to 160HP 6BT injectors. I'm thinking maybe the 190HP 6BT injectors would be the way to go, as I have an HTT Stage II compressor side for the engine [not installed yet]. I also plan 4" exhaust and later a water/meth injector so even more reason to go fat.

Thanks for the assist!
 

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Cummins injector assy # 3909522 shows 9mm. You will see the 7mm bodies are the prevailing body dia. now. You use a sleeve of sorts with them in the old style head. They changed head casting from 9mm to 7mm because of cracking issues. Don't let the injector body dia. hold you back, in fact I have been advised to go with 7mm injectors if I upgrade just for resale purposes.

The 3909522 are considered big injectors for the OEM Dodge CTD application. Alot of the How To turn up the VE pump write ups will say that in them, some of later 89-93' pumps do not see much performance gain because of the smaller injectors. The early non-intercooled trucks were better performing due to injectors, injector supply lines, pump timing and gov' specs. The only reason Dodge went to I/C at the time was to meet emissions. If you read up on these early emissions units they were some of the lowest power (turbo lag etc) trucks Dodge ever produced, 170,000 units.

Back to the good stuff, the 3909522 inj. assy is rated at 160hp in the 89' Dodge Cummins with CPL 0804, approximately 100 free hp is achievable with pump tweaks etc on that CPL (0804). The same injector # is listed for 4BT CPL 727, 857, 858. I would not spend money on injectors if I had these on my 4BT, I would spend that money on something else until I was absolutely in need of more fuel.
 

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Discussion Starter #5
Thanks for some great info, sdstriper! I appreciate you searching it out.

Right now I have the #3912468 mystery injectors so I'll have to do more research I guess. I won't use them if other injectors offer more bang for the buck. Thanks again for the help.
 
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