Da Groj

Cloud498 wrote:I'm probably going to order a better set of bump stops and NB tophats (more clearance than the NA ones) so that I can go back to the lower ride height in the future.

Function over Form. Be fast! Let the losers be pretty.

Loren wrote:Function over Form. Be fast! Let the losers be pretty.

Well yeah, but like Joe said, 4.5" pinch weld is an ideal height. It'll let me get more camber, too, if I need it. The new height should be better in the mean time.

I'm also gonna try to copy steve's diy cowl induction if I've got time tonight. Mine will be 2" pvc, though. It shouldn't make me any faster, but it may help fuel economy and will drop intake air temps.

Pinch weld height doesn't actually tell you anything about how much suspension travel your car has. You could take a stock suspension, put shorter tires on the car and reduce your pinch weld height. Center-of-hub to fender is a more relevant measurement. And you'll get varying opinions on what is "ideal". Ideal depends on a lot of things, like which top mounts you have, which bump stops you have, what your spring rates are, etc.

2" is probably way too small for intake tubing on a Miata if you don't intend to create a restriction. Look at your stock intake tube. Don't go any smaller than that.

Loren wrote: 2" is probably way too small for intake tubing on a Miata if you don't intend to create a restriction. Look at your stock intake tube. Don't go any smaller than that.

Stock snorkel is about 2" for an NA. I'm directly copying a diy from mazdaroadster.net http://mazdaroadster.net/showthread.php ... #post81068

I can't believe this is still out there, but this is what I did with my '96 back in the day:
http://www.cardomain.com/ridepost/21019 ... iata-mx-5/

Remember, while a 2" PVC pipe might mate up pretty closely with the intake box... the stock intake tubing is MUCH thinner wall than Schedule 40 PVC pipe. So, even if the outer diameter was exactly the same, the inner diameter is going to be smaller.

Look at a Randall. Roughly 1.25" x 2.5" oval tube. Much more area than 2" round. Cold air and the smaller diameter will conspire to give you better low-mid response. (smaller diameter = higher velocity) But, I would expect it to choke a little bit at the high end because it simply can't flow as much as it needs to.

Your throttle body diameter is, I think 55-56mm, which is right about 2.2". Smaller than that is not going to be ideal.

The cowl intake I have I made with 2.5 inch shop vac hose, which fits directly on the flange on the airbox. The stock tube is 2.5 inches, not 2. If you use a two inch pipe, you'll regret it. I have some vacuum hose I'll bring along tomorrow in case you want some. I also have a set of NB tophats I could part with if the price is right... (although I won't be bringing them...have to dig them out...).

Native wrote:If you use a two inch pipe, you'll regret it. I have some vacuum hose I'll bring along tomorrow in case you want some. I also have a set of NB tophats I could part with if the price is right...

I had already bought the parts, so I went ahead and put it together with 2" pvc. It pulls harder than stock (if only slightly) from about 5000-5500rpm to redline in first and second (I didn't test any higher than that) and doesn't have a noticeable change elsewhere.

That said, I'm not gonna turn down the vacuum hose. It's definitely not too late to change the design, and if that works better I have no problem accepting a better solution.

I'll probably be too focused on the course to do a side by side comparison tomorrow (what with you and Loren kicking me off of the M3 podium unless I drive better than I have been, not to mention Jason moving to M3 and learning his Miata and Sara continuing to improve) but I'll probably run both during the week next week and see what measurable differences there are in the IAT and MAF readings.

5k and up is what it does.

Here's where you chat about the event now that it's over.