Sherman M4A2 Detroit Injectors

[Malcolm Towrie]

Originally Posted by Tony Smith

Is an N65 a big enough injector size?

I have a few Injectors from Australian Grant Tanks, and these were the earlier type, but a Number 80. I realise that you can improve the performance, and efficiency (and emissions!) by upgrading to later versions of injectors and also the Cylinder liners, but would a N65 size Injector give equivalent power and performance to an earlier 80? I understand the earlier Injector has a different nozzle pattern that gave less efficient atomisation, but fuel volume per injection cycle is what makes power.

Tony, neat photos!
I checked through the manuals I have but I couldn’t confirm what injectors these tanks came with originally. All I know is the Detroit manual for the 71 series of engines lists the N65 as an option.
I found out today that one of the injectors I removed from this engine was actually an N60. It was the only one with the ID tag on the body missing. Somebody must have installed it hoping it was close enough! The part numbers stamped on the injector tip and the plunger gave it away.

The engine is running much more smoothly, with easier starting and much less vibration, smoke, and eye-watering fumes after replacing these two injectors. #6 is the only one left to be replaced as it doesn’t cause any significant rpm drop when shorted.

Our other Sherman has N95 injectors in both engines. That size isn’t even listed as an option in the Detroit manual! The manual is a lot more modern than the tank so probably emission concerns left it off the option list. A previous member here must have decided, to hell with the smoke, let’s get some real power.
Ironically, it’s no more powerful than this tank, but of course there are a multitude of reasons why that may be so.
Malcolm