injector options with which turbo

[92diesel250]

Hello everyone,

so here is the "short" story- bought recently a 92 d250- LE, ext cab, 5spd, 175k-ish miles, completely stock motor, 21cm housing, full set of gauges (tach, fuel press, pryo, boost)
i haven't touched the pump too much at all- i ground down an extra fuel pin i had (pretty aggressively) and it caused a very slight fuel leak from the slide pin oring and since put the stock one back in. but that is it.

i've read and learned a bunch from here, compD, DTR, diesel bomber but nothing really close to what i need answered.

i recently bought an he351cw to put on my truck- i am gonna clock the housing, already cut off the wastegate mount and polished the housing a little bit. i am planning on using a really simple spring gate setup i saw on one of these sites. I have a 4in downpipe and a 7" miter stack im gonna use when this turbo goes on.
but my question is on injectors-
what size injectors should i get? i was thinking 5x14, but...

i recently got my hands on an hx60w for a future compound build and i really dont want to buy injectors twice. i am a firm believer of buy once cry once.
now i am thinking 5x16, 6x16, 5x18, 6x18.
i know these last four choices are way too much injector for the 351 but what can i get away with for now on the single 60mm turbo that will be suited for my twin build 60mm over 80mm later.

please and thank you on any and all info you all can give.
drew

[BILTIT]

What are you using the truck for? With my 351cw i have enough fuel with stock injectors (1250+EGT's @40psi) when towing. I will be adding a HT3b in the near future and have a set of 5x14's for that setup. I try to keep things on the lighter side with fueling because i tow 12k lbs every summer.

[92diesel250]

The trucks main purpose is to drive and have fun. i daily drive it right now but i also have other autos to drive it need be.

it will tow eventually my k5 blazer on 1tons which is about 6ish thousand pounds - not counting trailer weight and other odds n' ends. the blazer is still street worthy and when it gets to the point isn't then ill start to tow it to the trails.

but for now hit the dyno, maybe the local 1/8 mile track and some shake down runs but really just an extra toy i happen to daily drive right now.
i know i will have enough air to burn some healthy fuel and i just want the possibility and potential to have the "right" (or most) amount of fuel.

i've read about people putting a really big injector in their trucks, much more than they needed, and just backed out the full power screw some till they reached a desirable mix of smoke/power.

drew

[RCCUMMINS89]

If you stay with the he351cw and you want a little more than your stock sticks.............I'd recommend a 5x11 SAC

If you plan on going twins.........I would recommend an extrude hone injector for BEST performance. However, a non honed injector - I would recommend a 5x14. An extrude honed injector, I would recommend a 5x13.


Anything larger and it simply takes a lot of supporting mods to make it more driveable.

Just an fyi - my goal is 500rwhp and I'm only running a 5x14.5 injector that we then extrude honed. I'm very borderline and have in fact lost a lot of on high gear lower rpm (under 2000rpm) driveability. I find myself absolutely having to downshift up any grade if I'm not going over 70+ when I'm in 5th. And that is unloaded.

Reason for the above is your overall injection pressure is decreased when you go larger on injector size.

[AHineman]

I'm very borderline and have in fact lost a lot of on high gear lower rpm (under 2000rpm) driveability. I find myself absolutely having to downshift up any grade if I'm not going over 70+ when I'm in 5th. And that is unloaded.

Reason for the above is your overall injection pressure is decreased when you go larger on injector size.

RC, I know you live in a place with much steeper grades than we have out here....but there are some decent hills in southern ohio and the surrounding areas of KY and WV.

My injectors are bigger than yours and I have no issues with having to down shift like you describe. Do you think it has more to do with your gearing/tire size and timing/turbo?

Also, I've never towed real heavy since all the fuel and twins....but with a load of 6k-8k or so, my truck spools faster. I run with the valet switch most of the time when towing, but it still spools sooner when loaded.

[RCCUMMINS89]

A lot of it has to do with elevation. LOTS OF IT

Also, you have an automatic.............and I have huge tires............and my truck weighs more than an ext. cab long box 4x4.


However, in saying all of that...........yours is one of the few that doesn't have an issue with this with this size of injector.

Oh, and in actual lpm wise............mine are actually within about 5lpm of 6x16. However, I know yours have also been extrude honed, so I don't know where your actually are.

[RCCUMMINS89]

Oh, and to add..........the issue is the same with he351cw I had.

Timing helps and is the biggest culprit of it........but there is only so much you can do with large injectors.

[AHineman]

My twin truck has a Getrag.

But.....my main point is though I have no real way to prove it, other issues cause your problem besides the size of the injectors. Just like you said; big tires, high elevation, etc.



With all of that said, maybe I'm just lucky.



End of my thread derail.

[RCCUMMINS89]

My twin truck has a Getrag.

Forgot about that. I'm just so used to everyone having autos

[RCCUMMINS89]

But, I'm basing my findings and opinions of the matter more off of what most of my customers and internet forumers run into.......as well as personal experience.

It's an opinion of my findings on the majority.

[92diesel250]

how should someone try and size injectors- lpm or orifice size?
b/c lpm's is constant standard- ex. 55lpm is 55lmp nothing more or less. but a 5x14 could flow xxlpm from one manufacture while another 5x14 flows yylmp from another.

also- how do you keep injection pressure constant? or how do keep it from dropping with larger injectors?

[RCCUMMINS89]

There is really no way to keep it from dropping with larger injectors. Less restriction is ......... just that.

One should go off of both orifice size AND lpm for the best match. Also not all injector companies and/or builders are the same.

The edm work is the most important.......then after that the builder. But of course both of those come after starting with a quality nozzle.