New exhaust extractors have changed rpms when VTEC will engage, rpms now have to be 5500+ original cast manifold VTEC engaged at 4200-4500rpm.
Can the exhaust be modified to give correct signal to ECU to engage as per factory settings?
Cheers kim for Oz

 

Swapping the factory exhaust manifold with a header will NOT change the VTEC crossover RPM in the tune... this can only be accomplished by altering the programming in the ECU. Now, the engine may "sound" different, but the function should be the same.

Incidentally, the factory VTEC crossover point for that engine is 5400 RPM.

 

Many thanks for your advice.
VTEC kick-in has always been around 4500rpm, we have had the car since new, 28 years, but note and DOHC VTEC kick-in is now different and over 5000 rpm since Hurrican extractor manifold headers. Honda tech advised VTEC change due to rpm/manifold pressure data change from manifold pressure sensor data output to ECU has changed. Will let you know how we go.
Cheers Kim Lake Cathie NSW Oz

 

Thanks again.
I have read the original specs for this engine re VTEC engagement and it confirms what you say, the factory rpm is 5400-5600rpm.
I think the original manifold has had a hole in it as well as a leaking gasket for years which has been reducing the manifold pressure.
The VTEC is now operating to specs since the new extractors have been fitted, it runs much quieter and flies!
I am not a mechanic but I have learned a lot today about the mighty B16A2 VTEC engine.
Thanks again.
Cheers
Kim

 

Have a B16 del Sol from new? Congratulations! Keep it forever!