Not trying to start the great debacle of tuning, injectors and PMRs. With that said, I'm just trying to understand what the best cc/% to run on my 02' would be. My truck is a daily work driver and pulls a trailer regularly, rarely anything over 10,000lbs. I don't think I want to put anymore money into it (turbo,hpop) after this. I just want some power to enjoy when I'm driving around town for work and on the weekends. I have a dp tuner and I will purchase the full force injectors through them and have them reburn my f5. It's my understanding that tuning is everything. I'm still a month away from having the cash to buy them, just trying to make sure I do this right and this truck eventually becomes a family heirloom. All input, advise, rants and tangents are much appreciated!

 

Yes you are correct that tuning is everything. In reality, it doesn't matter to PMRs what cc and nozzle size you go with. In the end, it's all about peak cylinder pressure, which is 100% controlled by tuning. My 02 in sig was running FF 250/200s on stock PMRs. And was a daily driver and towed very frequently often with heavy loads. Ran that setup for over 3 years before selling it in 2015. Saw it out on the road several months back, as far as I'm aware it's still the same.

Now what is helpful is to have a bit more info in your truck. Let us know what has been done (transmission, mods, gauges, etc).

Also, any particular reason for wanting to swap injectors?

 

Stock nozzle 160's

 

I've got gauges, billet torque converter, exhaust, Frx, transmission cooler and larger pan and some 35s, Detroit in the rear, stock gearing. Also an ats housing, tank mods, plenum inserts and some random things like coolant filter, afe intake. Honestly I just enjoy working on my truck and the joy it brings me and injectors seem like a fun time. I don't have scan gauge or fuek pressure, just boost, egt, trans.

 

Is there a way to monitor cylinder pressure? What are the key things that I would need to keep an eye on? Sry for the double post.

 

You don't monitor cylinder pressure, per se. You can check it with a contribution test (uses computer to drop them one at a time and measure the difference), or you can run compression tests through the glow plug holes one at a time with the valve covers off.

 

Some mild single shots would be the best upgrade. To get the most out of them and still have perfect street and towing manners, go with an 80% nozzle.

You can't monitor cylinder pressure without specialized equipment running on the truck.

However, a dyno pull can give you a good idea of what is happening with cylinder pressure, specifically with regards to torque. The higher the torque, the higher the cylinder pressure.

Maybe not an absolute, but the rule of thumb I used was to keep peak torque under 900 lb\ft. Too many PMRs went through blocks when torque exceeded that number. But again, it's not an absolute. Some have popped well under that number.

 

Unfortunately, neither test will give you any indication of cylinder pressure. Peak cylinder pressure occurs shortly after detonation, and in order to measure that you have to install a probe in the cylinder, which is typically placed where the glow plug would go. Not many people have this equipment around.

Contribution test only checks for a change in rotational velocity from one cylinder to the next, and only at idle. But it actually can't tell you what the actual cylinder pressure is, and it certainly can't do anything at engine speed and load where real pressure increases are found. Also a compression test is not a cylinder pressure test since a compression test is done without any fuel being fired, hence no detonation.

 

As Pocket said, tuning is 95% of the equation and he used to write tunes for his own truck and a few others.

After running tunes from all of the nationally recognized commercial tuners, I landed firmly with Gearhead.

Gearhead offers FREE tuning revisions for life as you upgrade your truck regardless of where or from whom you purchase your injectors, turbo, HPOP, etc.

I have run 5 different injectors. Stock 130/0%, 150/0%, 160/0%, 160/30%, and 175/80%.

For the absolute best bang for the buck, the most versatility for tuning: to keep EGT's in check, FIPW, ICP, HP in check, SOI timing, and ease of tuning, the 80% nozzles win hands down every single time.

If you go with stock nozzles, you are killing your ability to adjust all of the above due to the nozzle being a HUGE limiting factor. If you choose 80% nozzles, you will never regret it.

If a tune writer tells you to stay away from 80% nozzles, that should be a very large RED flag.

100% nozzles are a bit more difficult to dial in.

As Cleatus12R, one of our other members here who writes tunes pointed out, 30% nozzles are a waste of good money. I now know from experience.

The truck in my sig tows 16k up and down and around these small mountains called the Appalachians daily and I have ZERO issues with EGT's with 80% nozzles. With stock and 30% nozzles, I was watching the EGT gauge more than I liked and was looking for another gear half way through many climbs due to reaching the 1200 mark. Now, it rarely rises above 1000.

 

Thanks for the education/clarification on my end.

 

That's what we're all here for....... to learn

 

So 80% nozzles sound the best in terms of tuning. Im gonna call dp tuner tomorrow and see if I can talk to somebody who actually does the tuning. I see that I can get 160cc/80% or 180cc/80%.

 

I'm running swamps 175/0% injectors with 6 swamps and 8 gearhead tunes on the Hydra. 3 years and over 30K miles on it, 335K miles currently. It's my wife's daily driver and she really likes the power boost.


Planning to do injectors in the 99 dually this year. Will most likely try PIS 160/30% and plan to pull the dp tuner and UPGRADE to Hydra with Gearhead Tunes. It's mainly used to tow 10-15K lbs so not looking for anything crazy.

 

Is Swamps 175/146 what you are referring to when you say 175/0%?
If so, there is a night and day difference with that capacity when you go to a larger nozzle.

ICYMI above, if you are pulling that kind of weight, 10-15k, you would benefit greatly from 80% nozzles. I had 160/30's and had to watch EGT's constantly pulling that weight and downshift into 2nd in the mountains. Now, with 80% nozzles, I don't even look at the gauge anymore and stay in 3rd at between 2300-2600 rpm's.

Excellent plan of action on the Hydra upgrade.