Detroit 8v 53N

Your original injector set should have been the 5A50 or N45s.
Unless you have a problem, stay with what you have now.

Those big N series injectors will do nothing but smoke. If it starts at all. The largest N (& C) injector was a 50, the norms were 40 to 45. No HP increase without more air.

Diesel engines are not like the old Chevy engines. Bigger carb, blower, big loud pipes..
It will be very hard for anybody to soop up anything on these ole work horses.


To hang a turbo on a diesel, you need to change pistons and liners (different compression ratios),
Change out most of your exhaust system past the manifolds,
Probably change the cam timing.
Increase the heat exchanger capacity (more power - more heat).
Increase the raw water pump size.
Ad inter-coolers, to cool that hot tube air down before the blower.
Ah, the big one; New 4 valve heads. What you pour in, must get blown out faster.
Many, many, many mounting and hanging brackets.

And you just removed any life left in the engine, Without warning a grenade will go off.

It could be cheaper and (almost) as much fun to re-power.
Save the old 53s for e-bay or a DDC machine shop.

Now, If running well, go thru the water easy so to not spill any of that champagne you have on board.
They money your saving will more than take care of the coolers & chillers & inventory & lots of fuel for a very long range. Caviar & cakes ready next round.

Hang on,
Found a couple of 8v53n leads on your model number. reading up now.

List of factory injectors below.

I found the 270 hp model.
It did have the 4 valve heads.

No data on a 283 hp. Could be an after factory shop boosted it up a bit.
yours is probably maxed out in hp now.

Still can not find anything on 74 injectors in a 53. That must be the boost magic.

I know Chris did strange (some good) things to their gas engines.

Time to go to work. Do you have an OLD injector shop around?
Injectors have different spray patterns, delivery rate, delivery amount and more.
These differences are measured in micro amounts. Sometimes just enough of a micro of this, less a micro of that can give (give up) a few ponies. Maybe an old timer can help with better specs from his own injector cook book.

Don't ever exchange those injectors. If there really 74s.
If you ever get the a valve cover off, the injector number is on a round tag on the injector body.
I would guess after 45 years, somebody has already played mechanic a few times, installed and timed up a set of N50s.

Ralph told you in post #2 that the injectors were either 45's or 50's in all likelihood and didn't recommend changing them. You contacted Detroit Diesel and were told N50's, proving Ralph knew what he was talking about. You continue to talk 60, 65 and 70 although down from 75, 80 and 90. You've got 45 year old engines. Why are you so determined to change the injectors from those it was built with and for? You're playing with fire when you start doing that. Likely no one can tell you beyond a doubt what will happen, because no one has been moved to do what you're wanting to do. They can only tell you that it runs right with 50's. It might with higher but the odds are far greater of having problems than having success. As to any horsepower boost, I seriously doubt if on that boat and those engines you'd even be aware of it.

Just back in, long afternoon.
Is that a Chris or Detroit manual?

2950 rpm,,, gad we love those screaming Gimmes.
I think the TAs spun faster. OUCH...

Best plain advice; Enjoy that champagne, don't screw with those motors.

The 53 idle curse may be upon you if you do (whole chapter that's not free)..

I am impressed that an Non Turbo 8V53 can poke that HP out.

I have done quite a bit of work on new 8V71N's which were 290 HP out of the box, we used to strip the back end off them and advance the cam timing a couple of teeth and they would make 318 Hp. I think the Injectors were N55's.

The 53s are finicky and non forgiving, The 4 valve heads cracked a lot also.

Until you hit that wall of not enough air. Remember, their naturals. Blower ratio is already maxed out.

For your information:

8V-53N = 8 x 53 cubic inches per cylinder is 424 cubic inches.

The 71 Series started way before and was a legend starting in WW2. The 53 series came along in 1957 in pursuit of trucking /military / industrial markets. Even today there are 6V-53's being built new for the M113 Armored Personnel Carrier, as well as 8V-71's and 8V-92's for other countries land defense programs. These are new builds to relatively old specs, exempt from emissions requirements due to their military application. Proven, cost effective power to military specifications.

Attached is a power curve and injector list for the 8V-53N, marine engine.

Thank you for posting this information. I have these same engines with N50 injectors in my old 41 Hatteras. I'll have to admit that I had to Google the terminology to fully understand the fuel curve. It pretty much confirms my experience with my own boat. I tend to cruise at around 1600 RPM's and this gives me between 8 and 9 knots. The curve says 8 GPH for 2 engines. I'm happy with that.