Injector sizing

[Briankinley2004]

Would be cool if a chart did exist for Detroits. Next step up in size for performance gains, if even worth doing. Seems to come up a lot.

I have it for 8V71's but can't seem to figure out how to upload it here. If anyone wants it I can email or screenshot it and add as an image

[Timeless72]

I have it for 8V71's but can't seem to figure out how to upload it here. If anyone wants it I can email or screenshot it and add as an image

That is exactly what I'm looking for. Please send to mwood2580@yahoo.com. Thanks!!

[Avenger]

Too bad DD wasted all that money paying engineers when all they had to do to make more power was "turn it up."

[Captain Ralph]

I have it for 8V71's but can't seem to figure out how to upload it here. If anyone wants it I can email or screenshot it and add as an image

3 page PDF can not up-load here. I will type in the data of interest to this thread;

8V-71 230Shp N55 @1800RPM
8V-71 296Shp N65 @2100RPM
8V-71 325Shp N70 @2300RPM
Compression Ratio 18.7 tp 1

8V-71TI 340Shp N70 @2100RPM
8V-71TI 450Shp N90 @2300RPM
Compression Ratio 17 to 1

These would be DDC stock figures with normal cam timing.
Please note the lower compression ratios on the TI models.
Dated 9-95
No comments on what turbo is used.

[bigbill]

Why dont you people just pull the throttle back a little?

[Captain Ralph]

Why dont you people just pull the throttle back a little?

Some minds just can't handle the simple stuff?

I was just trying to be helpful in posting that info.

To be further helpful in case others missed it before;
It takes the same amount of horse power to move a boat at the same speed.
It takes the same amount of fuel to develop that same amount of horse power to move the boat at that same speed.
Slowing the boat down reduces the horse power required to move the boat at a lower speed.
Amazingly, fuel consumption is reduced.
F M
Unloading weight and trimming ship helps also. My second divorce proved this.

Reducing injector size just removes that reserve horse power, if or when you ever need it.

[whoover]

Of all the expenses in boat owning, broken things, things that are going to break, upgrades, maintenance, insurance, dockage why worry about fuel consumption. It is the cheapest part of the fun!

Walt Hoover

[cww]

What is smaller injectors going to get you that a lower throttle setting won't?

I had a dock neighbor back when I was in Daytona city marina who got angry at me over this exact conversation. He had a hatteras and was explaining that he'd downrated his engines by swapping in smaller injectors to intentionally make it a trawler. I asked that exact question, isn't it cheaper to just set the throttle lower. He started telling me how I didn't understand and it's bad for the engines because of cylinder temps, and he swore he got better fuel economy. I said it's physically impossible that the difference was caused by anything but him running the boat slower, and said temps are a function of the quantity of fuel being burned and either way whether it's smaller injectors or a lower throttle setting all you're doing is reducing fuel. He got super frustrated and acted like I was an idiot.

I'm not sure why this is an attractive idea to people or what drunk dock neighbor is telling people to do this (although I met at least one of them). It literally accomplishes nothing that pulling the throttle back doesn't do. But at least you've spent thousands of dollars on new injectors for no reason, and as a bonus the boat won't plane if you ever decide you want to.

[SKYCHENEY]

With the OEM setup, you can always get the temps up by pushing up the throttles. Run it slow all day and at least you can "clean them out" with a good high-speed, higher temp run at the end of the day.

[Timeless72]

Man, all these people wanting to go slower. I was hoping to add a few!