Gasoline injection best locations?

Hi Folk’s,

Love 💕 being here and learning.

I’m old like dirt 73 but have had a great life 60 years of working with Gasoline burning engines N/A and Boosted.

I need to learn a lot more and if I can help anyone I will try.

Working with a very old cast aluminum intake manifold with cross ram design.

Need some information on injector locations.

Thanks in Advance.

Mike 10.03.2022

What manifold and engine? I've the Smokey Yunich (IIRC) cross ram for the SBC, I think it was designed for dual 600/660 carbies?

It's going to depend on a few factors, such as budget, management, appearance, etc.

My personal preference would be to use TBs with the injectors in the TBs, for a 'stock' look - especially if I had the matching air clearer(s).

If not, it will largely depend on the rpm range you expect to use - from the Jenvey guide https://www.jenvey.co.uk/support/faqs/

"Where is the best place for the injectors?

Where one injector is to be used per cylinder the best compromise position is immediately downstream of the butterfly. This gains maximum advantage from local turbulence and gives results surprisingly close to the optimum at both ends of the rev-range. This is the recommended position for most applications.

For performance at low RPM, economy and emissions the injector needs to be close to the valve and firing at the back of the valve head. This is the favoured position for production vehicles.

For higher RPM (very approximately 8,000+) the injector needs to be near the intake end of the induction tract to give adequate mixing time and opportunity. The higher the RPM, the further upstream the injector needs to be. As a result, use of speeds above approximately 11,000 RPM may give best results with the injector mounted outside the inlet tract altogether (see our remote injector mounting). It is common to fit both lower and upper injectors in such a system to cover starting and low RPM, as well as high speeds."

When the injector is mounted close to intake valve for low and mid range RPM performance the angle which it's mounted at is also important... As Gord said ideally it should be aiming at the valves heads...