I/C sticks in NON-I/C

[m880cummins]

Title says it.

My truck has a 1990 engine and the injectors sound sticky and gets 17mpg and the best I ever got was 19.5mpg last summer. Has been slowly going down. I want to dyno it, get some numbers and then put smaller injectors in for better mpgs. The IC injectors have a different pattern but with rebuilt IC injectors, would I expect something in the low to mid 20s? I just want to get past 20. I know rebuilding the stock ones would help but I would like to save money as much as I can. My dad's is the same basic truck and he gets 20.8 with rebuilt injectors. I just want to get better numbers. I have plenty of turbo and fuel and the stock ones are plenty smokey. Do I have to worry about piston bowl size? What about the injector bushings? Do I need them?

Charlie

[Tacoclaw]

While I can't tell you for sure whether swapping to the IC'd injectors would net you better mileage, I will chime in on a couple of the points I think I know the answer to.

The bowls on a non-IC'd engine are bigger than an IC'd one, so piston bowl shouldn't be a concern. You can advance your timing more then normal with that setup, but I assume you'd be pinging and carrying on before you needed to worry about it. You can run 7mm tips in a 9mm hole with just the normal washers. I did it for about 8 months with no obvious ill-effects. It probably wouldn't hurt to get the adapter washers, but I wouldn't park the truck if I couldn't find them that day.

Personally , I would just rebuild the non-IC'd injectors. Since the 4.10s have you wound up so far, you might be able to take advantage of the extra timing of the other injectors, but it's going to lose some bottom end, and what fun is that?

I'd say those 4.10s are your biggest hurdle in the mileage category.

[cougar]

Going to an injector with more more holes may help your fuel mileage, but in order to equal the non-intercooleds 4X.013 you will need something like a 5X.012 or 6X.010. And make sure it has the correct spray angle. You can get yours rebuilt for less money.

[delinquent]

No worries on spray angles.145 or 155 will [list=][/list]work. I would do the swap and advance the timing. What turbo are you running? What size exhaust housing?

[Hansen01]

Before i got my injectors rebuilt i saw numbers as high as 23mpg straight interstate
but have not tested sinse turbo sway and rebuilt injectors