dsddcd

I am installing my Greddy kit on a local members API with an AP2 engine (Block Head and Cams). Currently he is revving the motor out to 9K and I am a bit worried that he is going to drop a valve or have issues at running above Hondas rev limiter on the AP2's.

I am going to do a ruff tune to get him by until he goes to the tuner and I want to make sure I don't have any part in a engine failure. As a precaution, I have already checked the valve lash, put in new plugs and did a compressor and leak down test. All tests went well but I am a little concerned.

What is your suggestions should I lower the rev limiter to 8500 or leave it a 9000?

Is there anything other than the springs and cams that should be replaced to allow him to safely hit 9K?

John_Z

Ease it down to 8500. The stock head is fine to 9k, the 2.2 bottom end isn't.

Soul Coughing

i have run 8.5k for 50k miles on my ap2 motor. On my setup i didnt make anymore power from running it out to 9k anyway.

To be honest, i'd be more concerned about giving him any tune before getting it tuned professionally.

Revenge

I would drop it down and let the tuner move up as needed.

dsddcd

I am confident with the my tunes but I want no liabilities so I am calling it a base tune and letting someone with a dyno and wideband verify my results and take liability. I run all my cars with conservative timing and fuel trims. I ran my car at 11.7:1 on the low end and ran it down to 11.3 by redline and then took out an extra 1.5 - 2 deg of timing for good measure. I want to make sure that climatic changes, fuels and other variables would all have to stack up to hurt the motor. I am less concerned about every last HP and more interested in reliability. Though I am sure a professional can find some improvments.

I will take the rev limiter down to 8500.

urBan_dK

With both the AP2 engine and the turbo running out of breath well before 9k on a 2.2 L engine, I think revving to 8.5k would be a no brainer.

ChefJ

^ beat me to it.

Between the turbo size and it being an AP2 it will run out of breath before you get to 8500 anyway. Most dyno plots on stock motors will show this.

dsddcd

I agree, though you need to plot and acceleration vs. mph graph first to prove the best shift point, on my AP1 this was app. 8750. He really wanted to keep the 9K redline, so I had to get educated on what the adverse effects of running it at higher RPM.

Is there any cases of a AP2 motor popping at 9K ?

urBan_dK

This has been discussed ad nauseum in many places. The piston speeds at 9k on an AP2 are much greater than an AP1. This causes extreme stress on the connecting rods.

The only interesting point in this case is that you are introducing FI into the picture. I've actually read that boost makes it easier to run a higher redline since it helps push the piston through its travel rather than the extremely abrupt changes when NA. I probably butchered that explanation but it's something to think about.

And your point about ideal shift points is well-taken, but I really do think that even after that you will see something well below 9k on a small-turboed AP2.