About advanced timing

This article dates back to 98, but it's real data taken by an enthusiast. http://realbig.com/miata/1998-01/5546.html

It supports the info presented in Norm's MCA article a few year's earlier which is a few more HP at low end, and little or no improvement at redline. The online charts in the GRM webpage are too small for my eyes, but I recall reading their magazine article and they also stated an improvement with timing.

Thanks for the reference. It does show noticeable improvements over the entire rpm range, not just below 2500 k, unlike the results GRM has given us. For example, in the range from 3.5k to 4k, where GRM show a *loss* in power due to the timing advance, these results show about 3.4 hp improvement, being a noticeable 5% increase.

However, I think these results do have some difficulties for use in judging the GRM results. The author notes that he/she is using premium gas. I could imagine that premium gas might burn a bit slower than regular (after all, it is slower to *auto*ignite and apparently typically has more detergents) in which case the timing advance might compensate for the difference in fuel.

Also, why is this engine pinging heavily on premium gas for anything above 14 degrees advance? Is this engine too full of carbon?

Then the author mentions problems with the dyno.

The figure is shown squashed. Try looking at it separately (right click and select 'view image'. Or simply load http://www.grassrootsmotorsports.com/IMAGES/ Miatadyno1.gif

Perhaps those 2-3 extra ft-lbf below 2500 are just enough to help get off the line, & may be quite noticable SOTP.

Maybe.

- bill

I guess it would help a bit in first gear. But how long do you drive in first gear and below 2500 rpm? Then, some people actually drive routinely below 2000 in 5th in the city.

I notice the author states this is 'cheap horsepower.' Has anyone caculated the cost of premium with advanced timing vs a not so cheap mod that would have a similar effect? I realize gasoline costs vary greatly. I saw a 16 cent difference in less than a half hour of driving. About a week ago. But let's say they all cost the same so calc'd for your area. For me, a 100,000 miles at 25 mpg is 4000 at 1.59 premium is 6360 vs.

difference. Cheaper than a supercharger, but is it really cheaper in comparison for just a few HP? Just wondering what other's thoughts

Good point, but I very much doubt you'd get 100K out of a CAI without replacing it. Gas prices I typically see put the difference at 10 cents. Don't you have to use premium with a SC, anyway?

Eric Lucas

The best idea is to use the lowest grade of gasoline that won't ping. For Serrano, with his supercharger, that's 92 octane, but I don't see the point of even considering that.

Not meaning to brag here, or seem insensitive, but if the cost of fuel were that important to me, I'd be driving a Civic or a Metro instead of a Miata. The fact that I'd need to use premium fuel after installing the supercharger didn't even cross my mind.

Do folks considering performance upgrades REALLY worry about what grade of gas they're gonna need afterwards?

Jerry & Serrano

They should, if the cost of the upgrade is important to them (and that's one reason for getting a CAI

Do you really need premium in January? I don't need midgrade until it's over 80F, premium over 95F.

I run regular, haven't done the timing bump.

Wise words my friend...

Panos