I recently replaced my old starter with this one:

https://www.dbelectrical.com/product...l-trans-1.html

This is the higher RPM S2 starter.

Everything fit perfectly fine, I started it and it fired right up, however there was a bit of a grind at the tail end of the car starting. I got back underneath the car checked the flywheel and starter alignment and tightness and reinstalled the starter.

I then performed a little test by engaging the starter with the accelerator pedal to the floor so the injectors would not fire. No grind at all.

I've come to the conclusion that the new starter spins much faster and with a good compression engine, needs a much shorter duty cycle to get the engine going. The grind I was hearing before was because the engine was already started after about one second of starting, and the starter cannot keep up with engine idle RPM.

So, while this may just be a common sense thing, I just wanted to put this thread out there for the future in case others encounter the same problem...let go of the key earlier, you don't need as much time to start with a new starter and a healthy engine.

 

interesting.. thanks for the insight..

 

I installed a new 2kw starter in my 04 and I never got a grind. This is some interesting information, as you would figure that the starter gear would retract fast enough and not catch on the ring gear.

 

Yeah it's odd, I never experienced it in any other car. However, this is an engine with 6k miles on it with brand new housings. Fresh plugs, BHR coils. I can literally just bump the key for like half a second and it fires up. Even the improved starter has a maximum RPM of about 300 RPM, while engine idle is much higher, and cold start idle even higher still.

The fact that it makes no sound at all when the injectors don't fire would lead me to believe that the starter does engage/disengage as it should. It makes me think the original RX8's had a slower starter for a reason, perhaps to prevent this very thing from happening.

 

You could very well be correct on that. I have the upgraded 2kw starter in my Nordic Green RX-8 and it doesn't grind. The engine however is mostly done for and is low on compression. This may have something to do with it not grinding. When I replaced the engine, I will see if the starter catches in the same way yours does.