$2 - RPM mod crystal

[altiain]

Way back in the early 90's, after the short nose crank was fixed, Miata Mag said the bottom end was good for 8000RPM. I believe 'em............ :)

Wouldn't be the bottom end that would worry me. I'd be more worried about floating a valve on the top end...

That said, Tommy Reynolds on the pointy board did something similar to his CSP '99 a year or two back (moved the limit to a real 7800rpm, iirc), and has had no problems with it that I've heard of. There are others, as well. Andy Hollis did muck up the head on his CSP Miata by overrevving it, but I think his redline was set well above 8000rpm.

I think this would be useful for the occasional few extra hundred rpm at an autocross, but I don't know that I'd make a habit of running it up to 8k on every shift at the track without beefing up the valvetrain.

[icepenguin66]

Where's Flyin96M in this topic? He was telling me about the rev limits before you float the valves and stuff when he was getting the stuff together for this 99 head swap. I think Merv is right; you can rev close to 8k before floating a valve but don't take my word on it.

[trackdog]

Garzilla did the RPM mod on my '96 and '99 and it works great. Thanks Chris. Yesterday we took a picture of the tachometer and speedometer showing 8000 RPM and 65 MPH in second gear on the '96. Engine felt strong with our TDR prototype intake and header we are developing all the way to 8000 RPM. Did not notice any valve floating. This engine setup continues to pull hard at high RPM. Our '99 has the AFR gauge and we noticed the stock ECU after a couple of cycles pulled the fuel management right in line. It works.

Good and quick way to take advantage of more RPM.

Gary

[altiain]

Our '99 has the AFR gauge and we noticed the stock ECU after a couple of cycles pulled the fuel management right in line. It works.

Good and quick way to take advantage of more RPM.

Gary

Is this an NA development '99, or were you using the stock ECU in the Track Dog?

I'd be curious to see dyno plots on a naturally aspirated '99 with this mod and typical bolt-on mods (intake, header, and exhaust). Might make for a nice, budget CSP engine setup.

[Titus]

Is this an NA development '99, or were you using the stock ECU in the Track Dog?

I suspect both... the Track Dog was running NA as a dyno test mule for different NA I/H/E parts the last time I saw it.

[trackdog]

Iain,

Both cars are stock blocks right now. The '99 is getting her engine back in next week so we can put the blower back on. We are looking into our prototype intake setup for production, but we want to dyno test first to make sure the dyno butt isn't lying. Our prototype header compared to the JR and the Racing Beat produced the most power and torque. We are making finishing touches on the collector and soon to be in production. We hope to have it ready for Christmas.

Gary