GRM Exclusive Reveal: Exocet Spec-A

Keith Tanner wrote:

z31maniac wrote:

Keith Tanner wrote: Yes, I read what you typed correctly. And I can see that the drawing shows a ridiculously low profile tire, meaning that you can't assume the same sidewall height as an "appropriately low profile tire". It's almost all wheel. Looks like Warren and I are on the same page here, my eyeball and his ruler are pretty close. A 19" wheel does not imply a 27" tire OD. Heck, I've seen Miatas with 18" wheels and approximately 24" tire OD. You're imagining a fairly high profile tire on that 19" of yours, the same sidewall found on a Miata with 14" wheels. In other words those are SUV sizes. Now, Warren's new renders, that shows a 15" wheel with 23" OD tires :) Which is how most Exocets will be fitted.

Is a 35 series considered low-profile? A 255/40/19 is 27.2, a 285/35/19 is similar as well. Either way, we continue to prove that everyone will argue anything on this forum with the goal of having the last word and being RIGHT!

35 is only part of the equation, of course. You can't really separate it from the section width. You're quoting SUV sizes. How about a 235/30-19 (24.6") Michelin Pilot, in stock at Tire Rack? And of course, the drawing was a fantasy render so why stick to actual available sizes. That drawing is running something like 255/5-27 tires. I agree the "trunk" is challenging on an Exocet. It's there to hide the fuel tank, and, well, it looks as if it's there to hide something. If it was tied into the roll bar braces or somehow looking as if it were involved in the body instead of just dropped over top of something ugly, I think it would look more integrated. Look at the Atom "bodywork", all of the panels flow nicely into tubes. Of course, with the design brief to make this bodywork backwards compatible, there are limitations as to what can be done. I know that new trunk is much more functional. The previous one didn't allow much in the way of options for fitting lights and the fuel tank filler was basically non-functional. This one's better on both counts.

SUV sizes? Those are the stock sizes on the BOSS 302.

Like I said

jmimac351 wrote: Warren, did I see where you were working on a tool for playing with color combos or was that for internal use only? (buying signal)

Working on automating it, or at least streamlining the process. I do not want to invite the swarm of color combo requests just yet.

Keith Tanner wrote: Like I said

Touché salesman

Good morning all.

I'm considering using my LS1 Miata as a donor for an Spec A Race version Exocet. As I try to learn as much as I can about how the V8 car parts would fit, it seems everything would portage over quite nicely.

However, I can't seem to find much discussion about V8 Exocet exhaust systems. My Miata is fitted with a custom, non-stainless system without cats. I believe I'd rather have something with cats (because without cats the fumes are really smelly) and I'm not sure my system would fit in the Exocet, so I'm considering alternatives.

Does anyone have experience fitting the Flyin' Miata V8 exhaust in an Exocet? Would it fit, especially through the transmission tunnel area and the muffler?

Thoughts and recommendations would be most welcome.

Bill S.

Hay Bill,

No one has completed an LSx-powered Exocet yet, so we don't have answers as to what drops in. I am 90% sure the FM V8 exhaust will NOT work as-is. We have a few customers building LSXocets right now, and they plan to get a custom exhaust, which really costs about the same (but takes more time). If you live near a major city, you should have a couple performance exhaust shops in the area that can take care of you.

I dunno, I suspect it will fit. But it's too late for us to check on our build.

If I was building a LSxocet, I'd be tempted to build side pipes. That would keep some heat out of the tunnel and nothing's more fun than blowing leaves from the side of the car. Get some metal core cats and it'll fit.

I'm revising my previous statement. After looking carefully at some FM build diary pictures and my CAD model, I think Keith could actually be right. Imagine that.

Just got done reading this thread. I must say, as someone attending school for mechanical engineering this is like porn...

Also, the urge to buy one of these is very strong. Sometime in the next few years I will likely have to get one, especially if I stuff my Miata on the track.

I believe I've made my way through all 27 pages of this thread, done research on local laws and insurance. I have a few questions.

1. Is 6'3" the maximum height for the race kit? Is 6'5" with a helmet in any way possible?
2. A.Please believe me when I say that I understand what the Exocet is about. One of the things I'm struggling with is let's say one was to go with a 1.8L Miata. We're talking about 140hp (say 110-115hp to the wheels) with say 1500lbs. While that's pretty quick it's not abnormally quick for a general sporty car. I'm not looking for a hyper car killer in a straight line, but if I'm going to go to the effort and cost I'd like the power to match the rest of the car. 200-250hp seems like a more appropriate match without going crazy. I like the idea of having as little effort as possible as I'm certain the overall build would be a lot of work. I'm not certain that adding a turbo kit is the best reliability and simplicity fit. Any thoughts on how to address this in a low effort manner?

B. With #2 in mind, I'm concerned the costs balloon significantly. eg. a 60k mile second gen miata costs ~$6-7k range in my area. $7500 race kit + $750 powder coating + $1k shipping + $7k Miata + $800 for a set of tires + $1000 other misc (?) = $18,050. I'm ignoring taxes, brokerage, etc. (I'm not trying to criticize the costs, I'm simply trying to understand the realities). Are there any reasonable ways to reduce these costs? Other thoughts?

Snrub, thanks for doing your research! Great questions.

6'5" would require a little creativity. A thin composite FIA seat, a tall quick release with a deep dish wheel, and a tilted back driving position would do the trick.

Yes, even at 1500 lbs, 140hp is still meager output in the days of 300hp minivans. Still, you'd be surprised how spirited these things are, even at stock outputs. Put some predictable but less-sticky rubber on there, and you're guaranteed a riot. Here are some cars that are slower than a 140hp Exocet in a straight line: E46 M3, every STi, 135i, Mustang SVT Terminator, s2k. With the open cockpit, it makes everything feel even faster, too.

That said, a little horsepower goes a long way in a 1500lb car. Unfortunately, Miatas don't do easy horsepower. With a shaved NB head, cams, high compression pistons, a standalone ECU, and other mods, you'll get stuck around 170whp for $3k+ in parts and tuning. Don't get me wrong, 170whp will get you past C6, E60 M5, and Ferrari 360 territory. My "problem" with that is that the BP engine loves boost. It's got factory oil squirters, and FM's turbo kit is very straightforward affair (read the XP-3 thread if you don't believe the hype).

For the same money you'd spend getting a BP to 180 n/a whp, you can have a tried-and-true, dead-nuts reliable 250+whp car. FM's turbo kits are very popular and have gone under constant development for over a decade. "Unreliable" doesn't apply here.

Here's another cool thing: the Exocet frame fits over the installed FM2 turbo manifold and turbo. That means you can do just about all the FM2 install work when you have the PPF sitting alone outside of any car. You can even hang the exhaust before dropping on the frame. XP-3 was my first hands-on experience with a turbo install, and it went very smoothly. It is by far the best way to get 200whp from a Miata engine. To save some cost without sacrificing quality/reliability, get the no-electronics FM2 kit and a DIYAutotune Megasquirt PNP.

Also, $6k for a donor? No way! Get an ugly one. We paid $900 for XP-3's donor, a pristine and fully loaded (other than some fenders) '99 with 155k miles. We haven't even sold all the spare parts from the donor yet, and we've made back our donor cost handily. A Race done "right" (new poly bushings, motor mounts, all maintenance items, painted subframes and suspension, new V-Maxx coilovers, new wheels, new tires, new seats, and any registration shouldn't cost you more than $14k. The customer-reported average build cost for a Sport is $10k-$14k, and the high end is filled with unnecessary big brake kits and the like.

Meanwhile, the Exocets sleep in Exo-Tempo.

Having driven a Miata with a turbo system, I can tell you that you won't be wanting for power. And, if it's a good kit, it's a wonderfully tractable power band and totally reliable with even moderate boost levels.

Snrub wrote: I believe I've made my way through all 27 pages of this thread, done research on local laws and insurance. I have a few questions. 1. Is 6'3" the maximum height for the race kit? Is 6'5" with a helmet in any way possible? 2. A.Please believe me when I say that I understand what the Exocet is about. One of the things I'm struggling with is let's say one was to go with a 1.8L Miata. We're talking about 140hp (say 110-115hp to the wheels) with say 1500lbs. While that's pretty quick it's not abnormally quick for a general sporty car. I'm not looking for a hyper car killer in a straight line, but if I'm going to go to the effort and cost I'd like the power to match the rest of the car. 200-250hp seems like a more appropriate match without going crazy. I like the idea of having as little effort as possible as I'm certain the overall build would be a lot of work. I'm not certain that adding a turbo kit is the best reliability and simplicity fit. Any thoughts on how to address this in a low effort manner? B. With #2 in mind, I'm concerned the costs balloon significantly. eg. a 60k mile second gen miata costs ~$6-7k range in my area. $7500 race kit + $750 powder coating + $1k shipping + $7k Miata + $800 for a set of tires + $1000 other misc (?) = $18,050. I'm ignoring taxes, brokerage, etc. (I'm not trying to criticize the costs, I'm simply trying to understand the realities). Are there any reasonable ways to reduce these costs? Other thoughts?

Snrub wrote: B. With #2 in mind, I'm concerned the costs balloon significantly. eg. a 60k mile second gen miata costs ~$6-7k range in my area.

When I read this I had a suspicion that you were on the north side of the border. To an Atlantean, these prices seem crazy for a used Miata, but are pretty much the norm up here.

Had a look at your location, good to see a fellow Londoner on the board.

In reply to NOHOME:

Can you buy from salvage auctions up there? Do the yards sell whole cars? I remember a big one out by your airport, but it has been years.

Snrub wrote: B. With #2 in mind, I'm concerned the costs balloon significantly. eg. a 60k mile second gen miata costs ~$6-7k range in my area.

Your problem is that you are looking at starting with a daily driverable car.

Think less "Driver" and think more "Salvage"

Find a low mileage one that got a ton of hail damage, was sideswiped, or the like.

Parts for these cars are cheap, when I needed a new motor for my 95 I got one with 28k miles for $675.

Just work on your scrounge-fu and open your mind up a bit. There are deals out there you are not considering.

Wouldn't live in too much fear of a miata motor with over 100k miles. (I know people running around with 150k mile cars that have been boosted to the hilt) These cars are stout. Furthermore, with junkyard motors being inexpensive, so what if you pop one? Just go get another. Its an exocar, so the install will be pretty easy.

btw, At $800 are you looking at Khumo V710 or Hoosier A6? I ask because competitive tires for my STS miata are more like $500 a set.

To clarify, XP-3's donor had been wrecked, but it didn't damage the subframes or suspension. The engine had broken off its mounts from the impact, but it has turned out to be completely reliable. We have not even opened the 155k mile motor. BP engines are way overbuilt.

Good to hear that further adjustments for height should be possible.

I'm just bit leery about cutting corners on the build and starting with very used parts, not just drivetrain, but suspension, and everything else. I would like the car to last and sustain abuse. Also, if putting in the effort and money to build the car I'd rather it be all "good" instead of "currently servicable."

Selecting a "newer" doner to have a better overall build doner means more money. Selecting a newer or older doner with a turbo kit adds thousands and complexity. It begs the question whether it would be wiser and similar cost to simply start with a lesser doner and a different drive train (eg. used LSx, etc.). That in turn means more work effort.

Regarding the tire costs, I might have been off slightly, I took what I expected the costs for my car (18" tires) and subtracted a random number. Also, tires are more expensive up here.

I appreciate the comparisons, but I think I have a sense of what it would feel like, but as suggested I'm sure being so exposed will make a difference. 1700lbs (car + driver) /110rwhp = 15.5lbs/hp. My RX-8 is say 17.3lbs/rwhp, my old RX-7 TII was likely ~11.8lbs/rwhp. A Mustang GT would be 10.6lbs/rwhp a new C7 9.4lbs/rwhp. Obviously power isn't everything, I'm simply aiming for something that is well thought out and all fun.

Power/weight doesn't give you any indication of how the car will corner and brake. When we had XP3 (225 rwhp/ 1500 lbs) on our track, we were using an LS3 Miata as a camera car (400-ish rwhp, 2500 lbs). Straight line, no problem keeping up. But the Exocet driver could maintain higher corner speeds and brake later, so he had to soft pedal a little bit to let the Miata keep up. This was a well-sorted Miata, too, and a less-than-optimized Exocet.

Do you have a friend in a state that doesn't see heavy winters? Even early NA Miatas here are pristine on the underside. Here is Kevin's first Exocet donor. There wasn't any rust or damage, but he decided to have it powdercoated because shiny. You're looking at a '91 donor that had 160k miles. It was bought for $1100 and he has sold $1600 worth of unneeded parts. The only reliability issue he's had with the car in the past two years is a crappy fake ebay header that cracked. That is TYPICAL for our customers, not the exception.

I don't think you and I have the same experience with used Miatas. Throw some new bushings and paint on it, and they're good as new. Flyin' Miata didn't even need paint on their donor components on their shop build. The stuff you use in an Exocet is generally very solid and lasts a long time. All the typical chassis rust spots are irrelevant for the Exocet.

Here is my power-to-weight math: www.tinyurl.com/power2weight

Does the Exocet work with both NA and NB donors? Don't the NBs have a more potent powerplant?

I'm not going to claim quite the same numbers for how little cars cost or how much you can get for the take-off parts. Atlanta is what I would consider a best-case scenario in this regard, with a strong market for used panels and a lot of cheap cars. We're just the opposite - you'll pay $500 for a 186k mile 1.6 automatic with a very tired interior (did it yesterday), not a slightly dinged up 1999 (as Exomotive did).

I know a pixel'd-out screenshot of a PDF is useless to you guys, but I'd like to at least hint to you guys the kind of analysis going on behind the scenes. FEA drove the design decisions for the frame, but it was always comparative analysis. As such, we never had a high-fidelity model that gave us confident real-world numbers. Now we do, and I think we'll be able to bump up our claims.

Let's just say the current frame is stiff. How stiff? We'll give out precise numbers once the physical testing confirms the analysis. Until then, I'll make a few conservative claims: torsion is at least 5x that of a book Locost frame loaded in the same simulation. The 190lb Exocet frame is also stiffer than the ~950lb frame of the Miata it replaces. That's absolute stiffness, too, which doesn't take into account the reduced weight. Less weight means less mass twisting the frame in a turn.

In reply to Warren v:

I was waiting for the pic to depixalize but it never did! Seriously, I quit reading Motoiq when they had some wheel they were highlighting and the far showed nothing, no loading conditions, no scale, just a pretty picture of a wheel all blue. It's nice to see a real far, but even better if we could SEE it.

All in time. I shall reveal the FEA goodies once we can back up my data with physical testing. It's tricky to give out data as a manufacturer versus a column writer. Accurate FEA on a big tube frame is difficult, and the software I am using has a bit of wiggle room compared to say, ANSYS. I don't want to claim a number and then have physical testing reveal a reality 20% lower. It would put us in a pickle.

It has nothing to do with hiding proprietary info. We're very open about our methods.