Everyone's talking about how the change in sound you actually hear in the B18C1 engine at high rpm are the secondary intake runners opening up, not VTEC that engages at 4400rpm. I've heard that not all the DOHC VTEC engines have that, is this true? I've got a B17A1 engine, and was curious if I've got that secondary intake runner thingy.

 

I don't think the B17A had the secondaries. I know the B16A and B18C5 don't have it. The Prelude VTEC engines might have it, but I'm not sure.

 

I have a low restriction intake and exhaust right now ( meaning loud) so as soon as I hit 5500-5700 (hard to tell with tach) my engine sounds like the fury of God. What is causing that noise if the VTEC engages at 4400rpm? I've heard 3rd Gen GS-R's and Type R's make a similar noise at autoxes. My dad has a '98 Prelude too, and his H22A makes a noise starting around 5700rpm that is similar, if a bit more muffled in his stock car. I always thought it was the VTEC, can someone shed light on this?

 

92-3 B17A = b16A with a stroker kit to 1.7...that's all, vtec switchover on a P61 ecu, is roughly 5.7k rpm...therefore what you hear is vtec, switch the cams to high out put mode....

in b18c (GSR) motor, vtec switchover occurs at 4.4k and 5.7k secondaries switch off to high flow mode...

 

Thanks for the enlightenment

 

the Prelude 92-96 SI and 93+ VTEC have the secondary runners also...

and the 01+ TL and CL Type S