jmann

Deerhunter What rearend ratio you running with that kind of whp on the track to get down the straight on the track with a 5 spd and not runout of rpm's? What do you have the Hydra set for redline at? Thanks

DeerHunter

Standard 4.10 R&P. Redline is 7,700. Per the FM gearing calculator, speed in gears is as follows:
1st = 50.3 mph
2nd = 77.2 mph
3rd = 100.9 mph
4th = 128.9 mph
5th = 162.3 mph

I haven't bothered to create a gearing chart, but I've never felt it fall out of the powerband with any shift over 6,000 rpm.

mr_hyde

iTrader: (4)

John, for our cars at the Ridge, I'd guess a 4.30 rear end would be better with those gears.

Seefo

iTrader: (5)

I am just playin' around sir. I couldn't help make a SP reference, plus I lived in Canada for some time. I like it up there!

bbundy

Id need a 4:10 with the Quafe wide 7700 rpm in top gear probably can't get there because the torque drops off at 7200. gets you to ~150 good enough.

Honestly I can't figure out how to make the quafe gears ratios work well for dual purpose with my car. Second gear is too tall. That was evedent after watching my car walk all over David de Regts car with his Quafe 4:10 in head to head side by side Pro-Solo competition. Top speed in second is not as important as being in the proper power band most everywhere else on the course. 8500 rpm rev limit fixes the second gear top speed issue.

The other problem with the Quafe wide is second gear is too tall for autocross and too short for a track gear. Best setup I think for the track would be a close ratio with a 3.636. 2nd through 5th looks real close to 3rd through 6th with the six speed just slightly tighter with that setup. Usable second gear for the track that way.

mr_hyde

iTrader: (4)

The quafe/4.3 combo would be too short for pacific and john doesn't autocross but is see where the spacing would cause problems.

Nagase

iTrader: (6)

Back when FM was building gearsets, they would let you mix and match gearing.

If this is still the case, wouldn't it solve some issues?

DeerHunter

I have a GPS-verified 155 mph with my car (there's a story there that I'm not willing to post on a public forum).

You may be right if you're running a more traditional autocross layout, with more closely-spaced gates. On the wide-open air base runways that we used to run on (before budget cuts made it unavailable for public rental), I was out of 1st before the first gate and pretty much kept it in 2nd gear for the rest of the run. It worked perfectly for me, as I briefly bounced off the rev limiter in a couple of sections and rarely fell out of the power band in the tight sections.

bbundy

I’m usually in second before I cross the start timing lights on most courses if not I’ll try and short shift. For prosolo drag tree lights, I don’t mind having a granny gear first. its actually easier to launch if you can run a higher rpm and control wheel spin with your right foot don't have to rely so much on clutch slip control with your left foot to keep the tires from spinning as you try to get it rolling fast enough to not stall the engine.

With a 7400-8000 rpm rev limit I would hit the rev limiter before the first turning obstacle at a national level prosolo. With an 8500 rpm limit problem solved. 60 foot times not really any better than the competition who was running both traction and launch control but the speed I was traveling at the 60 foot mark was much higher and acceleration rate from there on was faster.

jmann

Steven It sounds like you do mostly autocross. Have you ran much track with it and are you happy with the 4th to 5th shift with the .794 5th or do you wish you had the .881 5th of the close ratio quaife? Or with all the torgue is it a non issue?

I really like the 2nd in the close ratio for getting through turn 16 at the ridge, I wouldn't have to short shift as I have to now with the 6spd from 3rd to 4th, I could make it through it in 2nd.

DeerHunter

Unfortunately, we have a dearth of tracks in our part of the world, so 5th gear has never been an issue. The fastest track I've run on is the 2012 Indy circuit, created from our mostly-decommissioned City Centre airport. There were two straight-aways where I pretty much topped out in 4th gear, followed by hair-pins that stressed my brakes terribly. Here's a short video to show you what I mean:


I would have to say that I've never felt the need for a shorter 5th gear ratio. At highway speeds, the copious torque will propel me to 'ludicrous speed' in very short order. I rarely feel the need to downshift when cruising.

bbundy

Fast laps at pacific 6 speed 3.636 note: turn 8 taken in 4th gear. short shift to 5th for turn 9. shift to sixth gear going through the turn 10 shoot onto the drag strip. 6th gear all the way to turn 2. 180 degree turn 2 is taken in 5th gear. I gave up on 4th because I was still going too fast for 4th half way round the turn.

This was with the boost turned down to ~14-15psi making ~324 rwhp. to fit in NASSA TT2 with 245/40/15 DOT tires.

Fastlaps at Pacific Raceway NASA TT2 lap record in Turbo Miata 9/14/2013 - YouTube

DeerHunter

Sigh - that looks like fun! I really do live in the wrong part of the world.

Mobius

iTrader: (2)

So it adapting the T56 simply not feasible? I did a quick search but didn't find any definitive answers on why it's not. Engine location compared to an LS simply too different to overcome? What's the issue with mounting the V8 drivetrain to the BP?

Leafy

iTrader: (1)

Tranny is mega heavy.

bbundy

Adds like 65 lbs I believe.

orion4096

iTrader: (22)

Probably closer to 40-45 unless I'm wrong about the 5speed weight. It's ~125 lbs wet for a fbody transmission with bellhousing, shifter, and slave. I still don't think the t56 is the right answer for you guys. They are ridiculously easy to rebuild, though. I've always had my eye on the sequential boxes... they drop a nice amount of weight off the t56.

bbundy

Miata 6 speed I weighed was 75 lbs.

vehicular

iTrader: (3)

Plus they're huge, and expensive. And the shift feel sucks ding dong. An F Body trans feels like swishing a stick in a bowl of mud.

Chilicharger665

iTrader: (2)

MiataRoadster just posted a 3.308 groupbuy on FB. Does that help?