I have less than 10,000 miles on some DAP 50hp injectors but as many of you have said, always go bigger! I purchased some DAP 8 x 0085/100hp nozzles and put them on my stock/factory bodies that had less than 60k on them. A local FI shop checked out the bodies, installed the nozzles and popped them at 310. The increase in power going from the 50's to the 100's seemed greater than going from the stockers to the 50's. It has a nice little puff of smoke when you get on it from a standstill but is otherwise smoke free. I really want the power to kick in when needed up at cruise speed and I'm trying to pass some farm truck on the rural highway that is doing 53mph ( I call it the "slingshot"). With the 50's, I wasn't getting the quick acceleration I wanted at that speed but these 100's seem to have done the trick. 

 

I have the components for a Hx 35/40 in the garage (64mm turbine/60mm compressor wheel/12cm housing) along with a NIB PacBrake and NIB Quadzilla with extended wiring harness. I'm hoping to get the rest of this stuff installed in the next month or so. Since I live in CA, I'm limited to a Holset turbo due to smog check and I'm hoping the Quad with extended harness will let me get the Quad mounted in the cab, under the dash somewhere. Current use of the truck is just a 50 mile round trip commuter for the next two yrs until I retire and then a tow vehicle for my wife and I to use with our 25' fiver. 

 

It was 109 degrees today on the way home and I was cruising at 70mph/1900rpm/650 egt/6lbs boost with turnbuckled Hy35 and Edge EZ on #3. Does that sound like acceptable numbers? I'm hoping with the hybrid upgrade, Quad and some tunes from this site, I'll get better fuel mileage and be able to tow without worry about EGT's. 

16 minutes ago, 5akman said:

It was 109 degrees today on the way home and I was cruising at 70mph/1900rpm/650 egt/6lbs boost with turnbuckled Hy35 and Edge EZ on #3.

 

For your truck, tire size, transmission, and 3.55 gears - sounds like you are right where you should be to me.

 

- John

Those are good numbers. 

Not bad. The only weakness is the Edge EZ. EZ is just a stacking box that stack extra timing on top of the stock ECM tune. 100 HP needs different timing map to be optimal. 

 

150 HP injectors I'm 550°F at 66 MPH @ 2,000 RPM. 2 to 3 PSI of boost.

 

Optimal final ratio is near 3.73. From what you posted I pretty sure your running 31 inch tires, drop to 30 inch tires and MPG rise and EGTs fall. 265/75 R16 to 245/75 R16 is that change which produces 3.69 for a final ratio.

 

Just tidbits to get you better numbers.

That’s the same injector modification I’m planning on making. Going to the 100s from 50s. Glad you’re getting the throttle response you wanted. I’m also contemplating going down a tire size (285/75 to 265/75) based on all of Mikes final drive ratio comments. Here’s worn me down! But having just spent a week towing my camper and boat through the Washington passes I need better MPGs and reduced EGTs. Disabling OD does help with EGTs but its a bit noisy for me during long inclines at the higher speeds. 

285/75 R16 is 3.42 final ratio. Just 1 tires size up will make issues. Higher EGTs, lower MPGs, lower torque, shorter transmission life span, front end and steering issues including death wobble.

 

Stock tire size 265/75 R16 at 3.55

 

Just one tire size down 245/75 R16 will net you 3.69 with gains. Lower EGTs, more torque, better acceleration, better MPGs, etc. That's big part how I crossed the entire state of Washington for only a quarter tank.

I have less than 10k miles on the tires so I'm going to have to stick with them. I do plan on re-gearing to 3.73's. I've re-geared a few axles on my old Chevy Squarebodies and its not too bad of a job if you take your time to get the gear pattern set up correctly and not rush things back together. 

 

MoparMan, so by keeping my same tire size that I have now but re-gearing to 3.73's, I'll raise my cruise rpm by 200 or so. Are you thinking that even with considering the rpm increase, that I will see better fuel mileage or would that just be if I drop a tire size and keep the 3.55's? I'll soon have the quad installed and will be wanting to buy some tunes from you. 

5 hours ago, Hutch24v said:

That’s the same injector modification I’m planning on making. Going to the 100s from 50s. Glad you’re getting the throttle response you wanted. I’m also contemplating going down a tire size (285/75 to 265/75) based on all of Mikes final drive ratio comments. Here’s worn me down! But having just spent a week towing my camper and boat through the Washington passes I need better MPGs and reduced EGTs. Disabling OD does help with EGTs but its a bit noisy for me during long inclines at the higher speeds. 

The truck now feels more like my 500hp 2001 Dmax with built Allison transmission. That truck, even being a long bed, crew cab, raised 2wd vehicle, is the fastest rig I've ever driven. Its very light on its feet and now my Dodge feels more like that in terms of throttle response. Its sooo much cheaper working on this CTD vs that dmax however! 

13 minutes ago, 5akman said:

I have less than 10k miles on the tires so I'm going to have to stick with them.

Unless you want to change wheels also, I suggest sticking to the tire size you have. I decided to try 265/65/17s to get the 30.5" tire diameter and still safely fit the wheel width. They're fine, but a rare tire size for trucks if you need one while traveling.

 

I'm super interested in your injectors! I bought a set on sale around Christmas (2020? 2021?) and have yet to install them. 

9 minutes ago, LorenS said:

Unless you want to change wheels also, I suggest sticking to the tire size you have. I decided to try 265/65/17s to get the 30.5" tire diameter and still safely fit the wheel width. They're fine, but a rare tire size for trucks if you need one while traveling.

 

I'm super interested in your injectors! I bought a set on sale around Christmas (2020? 2021?) and have yet to install them. 

I should have read more and just bought the 100hp first and saved the 350.00 or so I paid for the 50hp versions. I'm really surprised as to how little smoke these produce. With your HE turbo and Quad, I'd think you're going to have a nice surprise when you get those installed!

I never did understand how tire size would effect the final drive ratio. Does it matter if it is a 30” or 60” tire? 3.55:1 means the drive line turns 3.55 times for one complete axle rotation right? So no matter what size tire the drive line spins “x” amount and the axle spins “x” amount. Tire should not affect final ratio. It does change the effective ratio. Meaning if that truck came from the factory with 265/75R16 and 3.55:1 gears  and you changed your tire size your truck now performs like it came from the factory with the different gear ratio (effective ratio). It does not change a gear ratio just the effective ratio. A true final ratio would be, depending on what gear your in, let’s just say 6th gear and the transmission ratio in 6th gear is .71 and your running 3.55:1 gears your final drive would be 2.5205:1. Meaning your engine rotates 2.5205 times and your axle rotates 1. No matter how big the tire is it will still rotate 1 time. Unless ratio’s work different on trucks.

@Caleb Hardy, I like what you wrote.  I think the words "effective ratio" are a better choice of words to present a case of how different tire diameters affect engine performance.  Earlier today I was writing about this subject, but I wasn't ready to post.  I am now posting below what my thoughts are.  I changed the words "final drive ratio" to "effective ratio"  as a result of reading your post.  Thank you.

 

I think the intent is to say, for example, "When a smaller diameter tire is installed on a truck with a 3.55:1 rear axle ratio, then the "effective ratio" at the ground would make the truck behave like it was closer to a 3.73:1 rear axle ratio."

 

I think that in order to make a fair comparison, the only time "effective ratios" should be compared between different vehicles is when the vehicles that are being compared are using a transmission gear that provides a direct 1:1 gear ratio.  There is only one gear in each of the three available transmissions for 2nd generation trucks that meets this requirement and that gear is a different gear in each transmission.

 

Direct 1:1 ratio gear are:

 

*  5th gear (NV5600)

*  4lth gear (NV4500)

*  3rd gear (47RE)

 

Over drive gears ore:

 

*  6th gear (NV5600) 0.73:1

*  5th gear (NV4500) 0.75:1

*  4th gear (47RE) 0.69:1

 

- John

Edited August 18, 20222 yr by Tractorman

👍🏻Thank you!! I didn’t realize that the ratios between 5spd and 6spd were so close. 

4 hours ago, Tractorman said:

I think the words "effective ratio" are a better choice of words

Agreed.

Of course having a 6-speed Allison with two well-spaced OD gears makes this fairly well a non issue except in first gear.

I don’t quite understand. 🤦🏻‍♂️

2 hours ago, LorenS said:

Agreed.

Of course having a 6-speed Allison with two well-spaced OD gears makes this fairly well a non issue except in first gear.

 

Actually Allison transmission you'll need 4.10 gears being I'm working with one current trying to build a tune and his cruising RPMs are too low. Then getting the proper tire size for the Allison OD is too tall. 

47 minutes ago, Caleb Hardy said:

I don’t quite understand.

I had forgotten your 5th gear is 0.71, which is close to my absurd 0.69. So ignore my comment above.

 

Why can't these designers give something like a 0.80 5th and 0.64 6th gear? I'm sure it's a good reason just would love to know the reason.

4.10 gears 245/75r16 tires and Allison

68MPH 

6th gear- 1950 RPM +-

5th gear- 2250 RPM +-

EGT’s still 750-850 at that speed in 6th gear. Down shift to 5th gear difference of 30+- degrees difference. Same as before with 3.55 when I kept it from going into 6th gear. (In my situation) I believe the Allison 2000 has ratio closer to what you wanting. Down side is that they have straight cut gears which are very noisy.(second hand information) I apologize for not knowing how to add the comments in relation to what I had just wrote. 

31 minutes ago, Caleb Hardy said:

how to add the comments in relation to what

Do you mean like the above?

Just highlight text and it SHOULD have the little "quote selection" box. I've found that if it doesn't, you can scroll your screen a tiny amount and it'll show up. Then tap that button and it's fairly self explanatory after that.

Edited August 18, 20222 yr by LorenS

Post your tune. 

2 minutes ago, Threadzy said:

Post your tune.

I think he's still running the Edge EZ, Adrenaline not yet installed.

18 minutes ago, LorenS said:

I've found that if it doesn't, you can scroll your screen a tiny amount and it'll show up. Then tap that button and it's fairly self explanatory after that.

👍🏻Thank you!!!!! Hahaha I’m a little slow hahahahaha