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bpimm
bpimm New Reader
12/7/14 12:29 p.m.

I like how this is coming together, John you could set the chassis up with the Miata pick up points and body mounting hardware and leave the drivetrain area free of any mounting points and just leave it up to the individual builder to add what they need for their application, not make it a bolt together kit.

bpimm
bpimm New Reader
12/7/14 1:20 p.m.
Ian F wrote: my goal is essentially a B-Mod car that can be driven on the street and be moderately competitive (locally). As such, making the car as light as possible will be a build criteria and I don't expect it to be cheap.

Ian, how do you build a gcr compliant street legal sports racer? I just figured I'd be stuck in Amod with the bike engine. Bmod would be better than Amod Pax wise but Amod is easier rule wise.

Ramona
Ramona New Reader
12/7/14 8:11 p.m.

Stunning looking car. I have a MX5 track car which is quite a bit larger than this. I would be using a complete MX5 [Miata] front subframe and steering. At the rear I would use a GM ecotec motor/gearbox and MX5 hubs. I would try and keep it Fiat so ideally hunt down at least the Fiat cam covers off a fiat from when Fiat used this motor. Lot of Fiats in that last sentence but Fiat were the major share holder in GM for a while and used this engine as did SAAB. Of course you could "make" a set of Fiat cam covers. This way it would maybe be more Fiat club friendly!

singleslammer
singleslammer SuperDork
12/7/14 10:01 p.m.
bpimm wrote: I like how this is coming together, John you could set the chassis up with the Miata pick up points and body mounting hardware and leave the drivetrain area free of any mounting points and just leave it up to the individual builder to add what they need for their application, not make it a bolt together kit.

I would be happy to pay extra for a bolt in Hayabusa/diff solution... That is just me though.

jmc14
jmc14 Reader
12/7/14 10:33 p.m.

I for sure will offer the chassis with mounts for a Hyabusa.

I found a 2013 Ford Fiesta with a manual trans that was hit hard from the side towards the rear. I'm trying to buy that right now so I can fit and offer that combo. And, I've ordered a Mazda Protege transmission with shifter and axles to see how that will work. I have an engine to bolt to it. I think the Ecotec option would be great and popular too.

I will offer the chassis with out engine/trans mounts for those that want to fit something different. If a customer wants to send me a different engine/trans I'll fab the mounts and jig it so that its' available in the future.

It's going to be fun to see the different combinations.

Ian F
Ian F MegaDork
12/7/14 10:49 p.m.
bpimm wrote: Ian, how do you build a gcr compliant street legal sports racer? I just figured I'd be stuck in Amod with the bike engine. Bmod would be better than Amod Pax wise but Amod is easier rule wise.

Like I said - more of a local thing, but while obsolete sports racers are common in B-Mod, I've seen bike-engined LoCosts even at the Nationals. We have a local guy who runs a MC engined LoCost in B-mod. In the unlikely event the car (and driver) prove fast enough to really place well in PAX, then I'd probably switch to A-Mod. While B-Mod is based on the GCR DSR rule-set, there are a number of deletions/changes for autocross (not the first time I've researched this).

bpimm
bpimm New Reader
12/11/14 11:16 a.m.
singleslammer wrote: I would be happy to pay extra for a bolt in Hayabusa/diff solution... That is just me though.

Don't get me wrong, I'd jump on it as well, there are just so many different ways to go I'd rather have a blank slate than have to redo one that was set up for a different diff setup. Sounds like it will be one of the options which is good enough.

bpimm
bpimm New Reader
12/11/14 11:23 a.m.

Something I've been thinking about is tire size, from scaling the picture of the car in the golf course and assuming a 13" wheel it looks like the tire diameter is about 20", there isn't much in the way of performance street legal tires in that size. Would it be possible to go up to a 22-23" tire without body conflict or raising the ride height? that would allow the use of 15" wheels and a much larger selection of rubber.

Ian F
Ian F MegaDork
12/11/14 1:05 p.m.

In reply to bpimm:

Good point... so I did some digging. According to this site:

http://www.automobile-catalog.com/tire/1968/254825/fiat_abarth_1000_sp.html

...the standard 13" wheel was fitted with an 80 series tires with an overall diameter of 22.6", so a 15" wheel may be OK with 205/50-15 tires on a 7" wheel up front and 225/45-15 on 8" or 9" out back.

bpimm
bpimm New Reader
12/11/14 1:30 p.m.
Ian F wrote: In reply to bpimm: Good point... so I did some digging. According to this site: http://www.automobile-catalog.com/tire/1968/254825/fiat_abarth_1000_sp.html ...the standard 13" wheel was fitted with an 80 series tires with an overall diameter of 22.6", so a 15" wheel may be OK with 205/50-15 tires on a 7" wheel up front and 225/45-15 on 8" or 9" out back.

Good info... That is some good news. Hopefully a wide 22.6" tire can swing under the front fender. There is a much better selection of tires available if we can use 15" wheels.

jmc14
jmc14 Reader
12/11/14 6:07 p.m.

Thank you for the tire info Ian. Do you, or anybody else, know what the optimum offsets would be for the wheels? And, what the out side tire to tire width would be?

I think that it would be best to keep the suspension pick up points the stock width of the Miata. That would allow sway bars to fit, the steering rack to be used, and wouldn't change the geometry at all. It may be necessary to widen the body a little. This can be done by adding small flares (like the Dino ferrari) or by widening the body down the middle. If down the middle it would give some more cockpit width. That might be an advantage. In either case a body can be modified as required and then make new sections for the molds. This would allow the body to be molded as original or with the mods done. That way a builder wouldn't have to do the modifications.

I've been looking at Protege specifications. It looks like they are essentially the same body width as the Miata. I know that Miata engines will bolt to to the transaxle. I haven't been able to confirm if the Miata block has the provisions for bolting the transaxles intermediate axle support bearing bracket. I'll bet it does though. What do you think the chances are that the transaxle axles are splined the same as the Miata and will fit with the stock axle length? Maybe that's too much to ask. :)

I like the idea of essentially a 1250# mid engine Miata with the Stinger body. I know that it wouldn't be the ultimate in performance but it would be a great little car. If someone had a Miata donor they could sell the transmission and differential to offset the cost of the transaxle. If someone had a Protege they could use the entire drivetrain and source the Miata components.

I have purchased a running/driving 114,000 mile, 5 speed Protege for $350. The body wouldn't pass inspection anymore but the drivetrain seems good. I am having a friend dismantle it for me so I can get ready to test fit.

I picked up a Miata for free for the suspension and other parts. Another one for $2000 that is supercharged for the engine, and a Protege for $350 for the transaxle. So far that's not too bad. The Hyabusa build will be more. :)

Having fun

mblommel
mblommel Reader
12/11/14 6:59 p.m.
jmc14 wrote: What do you think the chances are that the transaxle axles are splined the same as the Miata and will fit with the stock axle length? Maybe that's too much to ask. :)

I think the chances are pretty good. From what I've been able to dig up Protege, 323, and MX3 front hubs are all interchangeable with early MX5 rear hubs. Hopefully parts bin engineering will be our friend.

edit: the internet says the 1.6L miata rear track width is 1427mm or 56.181 inches. The Mazda BG protege chassis front track is listed as 1430mm, or 56.299 inches.

bpimm
bpimm New Reader
12/12/14 10:05 a.m.
jmc14 wrote: Thank you for the tire info Ian. Do you, or anybody else, know what the optimum offsets would be for the wheels? And, what the out side tire to tire width would be? I think that it would be best to keep the suspension pick up points the stock width of the Miata. That would allow sway bars to fit, the steering rack to be used, and wouldn't change the geometry at all. It may be necessary to widen the body a little. This can be done by adding small flares (like the Dino ferrari) or by widening the body down the middle. If down the middle it would give some more cockpit width. That might be an advantage. In either case a body can be modified as required and then make new sections for the molds. This would allow the body to be molded as original or with the mods done. That way a builder wouldn't have to do the modifications.

I'll measure the outside to outside tire width on my Miata today, I'll be where it's stored for the winter. I can then extrapolate the outside to outside on my race rubber, I run 225 45 15's on 8" wheels.

I agree on using the stock width on the pickup points and widening the body at the center line if needed, the body style is so sexy the way it is I don't think add on flares would improve the looks.

bpimm
bpimm New Reader
12/12/14 4:44 p.m.
jmc14 wrote: what the out side tire to tire width would be?

Front 64.5" Rear 65"

These were measured as close to the ball joint height as I could to eliminate variances for camber. These are 225 45 15's on 7" wheels and with 2.5* neg camber I have about 1" of clearance between the tire and the fender lip. as soon as I can find out what the offset is on the street wheel I can calculate how much wider the race rubber is, it still clears but not by as much.

PS Fender lips are rolled.

bpimm
bpimm New Reader
12/12/14 6:28 p.m.

The street wheels are 15X7 with a +38 offset, the race wheels are 15X8 with a +25 which would move the tire out .5". so the width would be Front 65.5" and rear at 66".

jmc14
jmc14 Reader
12/12/14 7:12 p.m.

Thank you very much for taking those measurements. It looks like I would have to widen the body by 4-5 inches to run the wider wheels and tires. I'll know for sure shortly.

I received word today that the molds are scheduled for delivery on Tuesday. I have appointments later in the week with my fiberglass and Chassis shop. The good thing is that the chassis shop, fiberglass shop, and powder coating are all with in a few miles of each other. We'll get a body made, build the frame, attach suspension and fit the body as needed. I'm hoping to get that done in Jan thru early Feb. Fingers crossed.

bpimm
bpimm New Reader
12/12/14 7:50 p.m.

In reply to jmc14: If that 4-5" is correct that will put the wheel mounting flanges almost flush with the fender opening so the Miata chassis pickup points would need to be narrowed. I'm all for the wide body option.

Can't wait until you have the molds to measure.

jmc14
jmc14 Reader
12/12/14 8:06 p.m.

I can't wait for the molds either. I think widening it in the middle will be the way to go. A wider cockpit might be good for my wide butt.

bpimm
bpimm New Reader
12/13/14 10:47 a.m.

In reply to jmc14: I could use the width as well. I will try to get out to the Miata again and make a giant caliper to actually measure the fender opening width front and rear, that should be a bit more accurate than dragging a tape under the car.

Might consider making the wide body a bit wider than the Miata is just for more tire for high horsepower applications.

Chet
Chet New Reader
12/13/14 1:16 p.m.

Just my experience but I think you'll find that it's very easy to decrease both the performance and fun aspects of the car by using tires / wheels that are too wide / heavy.

Remember the car will be much lighter than almost anything else so getting the tires to properly warm up can be an issue.

Chet

singleslammer
singleslammer UltraDork
12/13/14 3:04 p.m.

Chet, do you have a locost? Also, good point. Are there any decent tire left smaller than the 205?

jmc14
jmc14 Reader
12/13/14 3:28 p.m.

I met Chet years ago at the Kit Car show at Carlisle. I was there selling a car that I built.

Chet imports and sells the Fury Menace. This is a very cool lightweight car that he powers with a Hyabusa engine. Obviously he knows a lot about using the Hyabusa in a car. He's a great guy to talk to and he has graciously offered to help me.

singleslammer
singleslammer UltraDork
12/13/14 4:48 p.m.

There was a builder a few years back on the locostusa board when I was researching those. I am curious what the additional width would do in this case. I may have missed it but what is the wheel base? If it is in the upper 80s the Miata track might be alright. I am a fan of narrow tires with limited traction for the fun factor.

jmc14
jmc14 Reader
12/13/14 4:53 p.m.

The wheelbase is 86.6 inches. That's 97 percent of the NA/NB Miata's 89.2 inch wheelbase. The NA is 65.9 inches wide. 97 percent of that is 63.9 inches. The SP-1000 is 64 inches wide. Only a slight flare of 1 inch per wheel arch would be required to allow the same wheel selection a stock Miata does. That might be the simple option.

Ferrari Dino [URL=http://s1143.photobucket.com/user/jmcbigbelly/media/ferrari-dino-06_zps3d9813ad.jpg.html][/URL]

bpimm
bpimm New Reader
12/17/14 9:30 a.m.
jmc14 wrote: I met Chet years ago at the Kit Car show at Carlisle. I was there selling a car that I built. Chet imports and sells the Fury Menace. This is a very cool lightweight car that he powers with a Hyabusa engine. Obviously he knows a lot about using the Hyabusa in a car. He's a great guy to talk to and he has graciously offered to help me.

That's great news. knowledgeable help is always a good thing.

The small tire for heat issue is definitely a concern for track use, but what about street use where the tires will probably never see optimum temperatures? From my experience it seems that more cold rubber grips better than less cold rubber. The car I'm going to replace with this car weighs in at 900 Lbs with me in it. In an autox application I don't get heat in the tires unless I can run 2-3 back to back runs. I tried 6" wide Hoosier R25B slicks to see if they would heat up better than the 8" I was running and there was a definite performance loss especially in the acceleration area. I then went to 10's in the rear and got an increase in grip out of the corners under acceleration. All runs were on tires that were not up to temp. My concern is that with a 1400 Lb car (with me in it) and 230 HP at the wheels, (HP needed to maintain the power to weight ratio I have now), If tire size is limited to 195-205ish size tires they would be inadequate for the power level.

I'm planning on using this car for street, track and autox so having a smaller set of tires for the track is easy to accomplish as long as the car can accommodate the street or autox tires as well, I figured I'd be running 10's on the rear on this car as well. I may be wrong in my thinking but that seems to be what worked for me.

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