V8 Miata options

So I have a 90 Miata, I have been thinking of turboing it but it seems that in the end I would be spending a bit of money to get it where I want it between turbo parts, engine management, exhaust, clutch, diff, etc.

Then I started thinking about how I have always wanted to have a V8 Miata. I would do a 5.0 Ford for budget reasons unless there is a way to do a cheap 5.3 LSx.

What kind of rear end would I need with a stock/mild 302. Would a 1.8 Torsen hold up to that power or would I need to go with something stronger?

Any tips for doing this on a challenge budget? Not including the price of the car, ~$2000 for just the conversion.

The only way to get it done so cheaply is with lots of freebie/junkyard parts and some creative accounting. There have been V8 conversions at the Challenge before, but they all have been pretty serious builds in terms of the skill, labor and tools involved.

EvanB wrote: What kind of rear end would I need with a stock/mild 302. Would a 1.8 Torsen hold up to that power or would I need to go with something stronger?

I have been wondering this very same question. Aren't the 1.8L miata rear ends the same as the FC RX7's? If so those guys don't have much trouble with mildly built v8's in slightly heavier cars? Keith???

Thanks

I know the RX7 TurboII diff is also a commonish swap into a Miata and they seem to hold up to V8 conversions fine but it seems like it would be easier just to swap in the Torsen.

Although, now that I think about it, I wouldn't be retaining the PPF anyway with a T-5.

Easy to do. Just buy ours.

Look at page 66 of the current issue. Hopefully Tom will pop in a post that photo from the magazine.

The only reason we were able to do it within budget was because we bought it as someone elses failed project for $1100. The cage cost $400 and wasnt part of the budget.

The car came with all the big parts (motor, trans, rear end) and the suspension was already done. It was just Eibach Springs and KYB plus a FM front bar. We did not touch the paint. It still cost quite a bit to get it running. We got the tires and rims cheap and it still added up. The driveshaft was not cheap. The exhaust was about $300 and it rubs in places. Just the hoses and parts for the remote mount oil filter were a bit much.

We ran a rear out of a Turbo II RX-7 which we had to make a mount for.

Despite all this and a clutch that would not release we placed 16th in the challenge with a stock 5.0. It ran a 14.5 in the 1/4 mile. The launch method for both the autocross and drag was to push it to the line. Put it in 2nd then crank it over til the motor caught and off you go until you rev match to third and fourth. Should be in the 13's when we fix the clutch issue.

Email me if you are interested. I doubt you will be able to do it for less than we are selling it for. gregory.k.voth (at) gmail

You can see a bunch of pictures in the car in my wife's album. http://picasaweb.google.com/lilbluba...EQ&feat=email#

Also this video from an autocross run. In third the whole time except for the start. http://www.youtube.com/watch?v=Ic81M-TmQV4&feature=channel_video_title

Same run from outside the car. http://www.youtube.com/user/lastminuteracing1#p/u/21/dDpfHx0Kt44

Drag strip run. http://www.youtube.com/user/lastminuteracing1#p/u/2/4c2s830NWF4

Rather than starting my own thread, I'll just tack into this one.

Anyone know of any full-California legal V8 Miatas? I know it's within the scope of the law provided you either use a newer motor than the chassis, but being that all the factory smog equipment is required, I'm not sure what actually fits when you're not allowed to just custom fab up exhaust.

GM Link

You can get a fully 50 states legal LS3 crate engine.

RossD wrote: GM Link You can get a fully 50 states legal LS3 crate engine.

Yeah, the engine part is covered. The question is if it's possible to fit the engine plus all the stock smog equipment.

To give you some idea, LS swaps are common in S-chassis nissans. BUT, the steering shaft goes right through where the stock exhaust manifold goes. So, you can get it stickered as legal with no steering shaft but as soon as you put exhaust in that routes around it, you're techically no longer legal.

I wasn't sure if the Miata had any similar issues.

EvanB wrote: What kind of rear end would I need with a stock/mild 302. Would a 1.8 Torsen hold up to that power or would I need to go with something stronger?

Of the two that I know, the 5.0 car has a modified Thunderbird rear under it. I don't know the exact extent of the modifications, but I think maybe it has T-bird joints on the inner ends and Miata joints outboard.

I also know a carbureted 306-powered '91, but I don't know the rear under that. I can find out if you are interested.

I put a 5.0 Ford into a '92 and ran the rear end from the 1.6 for over a year and replaced it with a Ford 8.8 conversion that I bought from Racing Concepts before he disappeared. I took it fairly easy on the 1.6 rear, but it still ran 13.6 with a mostly stock motor, and was still working fine when I replaced the rear end with the Ford unit. I also still have the stock 3.91 rear end in my '88 RX7 with a 350 Chevy. That car has run 12.3 with no issues. I believe that rear end is very similar to the 1.8L Miata rear. The guys that I know of that have broken that rear end, didn't have problems until they switched to slicks. I know of a Convert RX7 (Buick GN turbo engine.) that runs low 10s on a turbo II rear end and drag radials.

Steering shaft will interfere with a stock manifold an a LS. Sanderson makes a shorty that will work.L33's can be found cheap(I paid $450). A turboII reared would probably hold up.

http://monstermiata.com

They sell the V8 kit, and parts. (7.5 LSD rear)

Yea, unfortunately $4000 for just the kit is a bit out of my price range.

I am very tempted by Greg's challenge Miata. Anyone in Ohio want to buy a rust free 90 Miata with 109k miles?

In reply to EvanB:

send me info, camargo123@hotmail.com

EvanB wrote: I would do a 5.0 Ford for budget reasons unless there is a way to do a cheap 5.3 LSx.

Read My V8 Miata thread for info on my $150 LS1. I have a wrecked 5.3 Z-71 coming this weekend for $1000. I'm hoping to make money on that one.

paulmpetrun wrote: I have been wondering this very same question. Aren't the 1.8L miata rear ends the same as the FC RX7's? If so those guys don't have much trouble with mildly built v8's in slightly heavier cars? Keith??? Thanks

My friend with the built LS1 FC kills rears at the rate of one every six months like clockwork.

I just bought a zero mile Getrag rear for use with the FM kit for $375 shipped to my door

Stealth Canoe !

plance1 wrote: In reply to EvanB: send me info, camargo123@hotmail.com

Me too.

After some thought I decided to hold onto my Miata. I am still interested in a V8 swap but I will probably hold off on it for awhile to save up for a proper LSx swap.

bravenrace wrote:

plance1 wrote: In reply to EvanB: send me info, camargo123@hotmail.com

Me too.

Ummm no geniuses, just a long time poster, a member of the Cincinnati Miata club who likes Miatas.

I'm confused