So I would like to say I have owned my miata for over a year now. I have read and perused and stalked many forums with v8 swap content for most of the time I've owned the car.

Second the last car I owned before my miata (aside from the talon I traded for it) was an 88 RX7. I had wanted to swap that car, but it was ragged out, and had no title. I drove it until getting a new tag became impossible then sold it for spares.

I liked it a lot, but the interior in them sucks ***. **** pile and crappy plastics/dash quality. Most of the interior in my miata is pretty nice, the glove box rattles a lot but I get over it.

So my main is issue with the V8 swap is the fact the biggest street tire you can fit is a 225. My second issue is that, the cost of the LS1 swap into a miata is greater. I want a nice street car. I don't care as much about Track Performance. I may go to the strip a few times a year, but I will never get back into autocross. I might get lucky and make a trip to Barber 1 time a year.

So your honest opinions V8 miata owners/builders. If you could do it over again, Miata or RX7?

Miata Pros
Less Weight
Open Top
Better Steering
Better Interior Quality

Miata Cons
More expensive to swap
Not as "Sporty Exterior"
Narrow Tires
Small Trunk. Still useful for grocery getting.

RX7 Pros
Storage Bins
Big *** trunk area (comparatively)
Bigger Passenger Compartment (For fat guy seats)
I love the FC (FC Wins hands down in looks department vs NA)
Cheaper V8 swap stuff
Can Fit some wide *** tires
Easy to mount diff options (TII + 3.73 Gears from 929)

RX7 cons
Shitty *** interior. Aweful aside from the storage bins which I loved
No open top. The FC Vert is ugly as sin IMO. It was a Hardtop coupe converted to be open top. Will not own.
Steering is good, but not as good.


I really think I should sell the MX5 and pick up another FC. But I just hated the interior. Which the carpet can be easily fixed. However any sort of dash swap will cost way too much. Best I can hope for is updated recovered door cards, and maybe a leather wrapped dash. I wont do ricer fiberglassed dash stuff.

 

Welcome to the forum!

 

Thanks Rick. Any opinion on FC vs NA?

 

Welcome. For width check out the body from Monstermiata.com you can go wider you'll just need to upgrade to a 16 wheel

 

You are right about tire selection, at any wheel size it stinks due to height restrictions. But if you are only a street car then who cares that the Miata has limited tire sizes? Or if it's lighter and handles better either.

Looks to me like you answered your own question. The 4th one down in the RX pros answers the question. The best part about owning any car is looking forward to driving it because you love the car. The RX has 7 pros and 3 cons and the Miata is 4 to 4. RX wins. If you can go to an ND those numbers would be off the chart.

To me a much bigger question is do you want to do a swap yourself of buy one built. If budget is a big deal you will come out way better to buy one. If the adventure of the build is worth something to you then you need to do that.

To answer your other question if I had to do it over again I would have still built a V8 Miata but I may have done a few things different in the process. And as for rats my car is about as ratty is it gets but she's the rat I love!

 

There is no question that building it would be cheaper than buying. I own tools, welder, engine hoist, stand, torch, etc. All of the finished cars I've seen have been in the 10-16k range for a miata. And 8-14 range for rx7.

While on the looks Dept, I like the miata, and it is more fun to drive than my fc was. But I suspect that it was largely due to the fact my FC was a n/a s4 with 160k on the clock. Pretty high for a wankel. It was slow.

I would also have to disagree about the lightness, handling, and tire size. 1st gear being unusable on the street would suck. Lightness, Handling, and Looks are the main reasons why I wouldn't just buy an F-Body and be done with it.

 

Me and probably most everyone here will agree that you are incorrect on the first statement of your last post. You will be able to buy one much cheaper than you can build one. If you think otherwise, you just haven't done enough pricing.

I am building mine just because I trust myself more than a stranger when it comes to my own safety.

 

If you can find an LS1 swap for around 8 grand please do let know. I intend to have my basic swap done for that or less. I am an ASE Certified Mechanic in all 8 areas with 7 years of Experience in industry with a further 6 years of shade-tree mechanic/restoration experience. I've been turning wrenches for the better half of my life.

Now with the miata, I know that it will end up costing more simply because there is more to do. The brakes are not up to the job, the suspension will have to be tweaked, k-member modifed, oil pan modified, Custom prop shaft.

Actually the more I think about how much more work has to go into a miata, and how limited I would be by the miata platform I think the rx7 is hands the better choice.

I just hate to let my miata go. Such a good car.

 

You are not including the cost of the car you already have and I still believe you aren't considering all that needs to be done. So if you take the cost of your car, bump up your estimate, you could find a good finished one for that cost. If you do choose to do a miata, I would love to see it done for 8k.

Don't get the wrong impression, I'm not trying to poo poo on your plans, and I definitely don't doubt your abilities ... I don't know you. But from experience, i know that there are a lot more costs involved than you originally expect. We are on your side, just be cautious with low balling your expectations. Keep us posted, I love to see other projects in progress, keeps the ideas flowing.

 

My point about not caring about handling and weight in a street car is you can't push the car on the street like you can on the track and both options will destroy 99% of the street cars you mess with anyway so a few lbs won't make any difference.

I don't know what you are talking about having 1st gear not usable. I have never heard of or known any swapped Miata that the owner would say 1st gear is unusable.

If an F body is an option I have owned 4 of them and really like the cars. 2000 or newer Camaro SS or WS6 bird is about as bang for the buck as you can get. If you have a few more bucks the GTO is really hard to beat too. No question they are 30% too big but excellent cars none the less.

Tanro if I understand you right you are planning an LS build for around 8 grand? Can you post your build plan estimate for us to see how you got to that number?

 

Here is the sheet I did before I started my build.

 

what did the "final" ------ sheet look like (to date).

 

I was trying to figure out a way to post that. Can you read this? Note this does not include the engine or transmission. This is only conversion costs.



Note 2 I am not claiming it couldn't be done cheaper but from the dozens of build threads I have read this is pretty typical.

 

LS1 Car 3500-5000
Drive car until I am satisfied that I have worked out any bugs I need to.

Remove Drivetrain, Throttle Cable, PCM, Harness

Sell F-Body or Part out. Hoping to make about 1000-1500 back from this.

So I am sitting at 2k-4k for swap drivetrain. So that leaves me with the other half of the build.

Hard parts I can get through work on commercial account, No tax. At cost.
manley Double roller chain set 151.00
Wailbro 255 LPH intank fuel pump 88.50
Melling oil pump 110.00
LS7 clutch kit 205.55
Radiator will need to figure out. But I am allocating 350$

Hard parts I would have to order, or fabricate something similar.
Ronin Speedworks LSx install kit 569.00
Ronin Speedworks T56 trans brace 215.00
Hinson Wilwood Clutch master 96.00

Taurus Fan Junkyard - 40$

Misc Electrical Supplies, Tape heat shrink solder resin split flexbraid loom etc 300$

Now that brings me to a woping total of 2125.55. Most of this stuff I wont have to pay shipping. But lets say I add in 400 bucks to pad anything I may need to have shipped, or find a better part. 2525.55

Okay so diff? In the FC it is pretty easy.
FC T-II Diff assy, 80$ Can get local
929 3.73 diff 250$ Sourced one.

Sitting just shy of 3k now. So the total cost ranges from 5-7k esitmated. Brakes? Well the FC brakes are actually up to snuff. So new pads, rotors Braided lines. Sure.

Wheels and tires yep got those lined up. Gonna run about 1200 for the setup I wanna use.

So I am looking at somewhere between 7 and 9k for swapped rx7. I am discounting the body as I know I can source an FC if I sell the miata. Yes I know I still need to address fueling beyond the intank wailbro.

Alot of it helps that 1) I can fabricate stuff, 2) I can get stuff through work at cost. 3) I am willing to put in the work to resell the stuff I dont use.

I could probably do it even cheaper if I wanted to run a truck engine but then you have futz around with getting all the correct brackets and accessories. I am not looking to build the engine, just get it on the road and then upgrade it later. Ultimately I know I would not be happy buying someone else's project as I would find stuff they did I would do differently. Happens every time I have bought something that had been modded in the past.

I've driven F-Bodies in the past. I hated them big wiggly turds. Only thing I liked was the noise out the back end, and the straight line acceleration.

 

I have not had any coffee yet so I hope I don't come across as an *** here. There is no question I could have cut a few more corners in my build and been closer to 8 grand for swap costs. There is equally no question if you build either car your final tally sheet is going to be at least the same percentage higher then your estimate as mine was.

I've probably read 100 build threads on a half dozen different forums and they nearly all look just like my numbers. It doesn't matter if you are a total diy guy that can fab even the most complicated part or you buy everything plug and play it's the same story. Everyone starts with a plan like yours and ends up with a much bigger number at the end. Why? Because there are 2 factors that don't go into anyone's estimates that busts the thing every time. While I am here I may as well.... and oh ----. You have been wrenching plenty long enough to have lots of examples of both of those situations.

Again I apologize for my morning rudeness and I don't want to come off as saying you don't have a clue of what you are doing or that I have all the answers. All I am saying is if you notice my join date and post count you'll see I have seen a lot of projects come and go thought this forum. They all start with a plan that makes perfect sense to the owner and end up 50 to 75% over budget when they are done. Oh and that's another thing no build is really ever done...

 

You can't build it on that budget. NO WAY!! I know that Jim really wanted to say that, but he is too polite. Me, on the other hand, not so much after my morning beer.

On a side note, welcome & good luck on whatever route that you decide. We are here to help & keep you motivated.

 

Yeah I know. Its hard to stay on target and on budget when you so things and go "Oh while I am here" but usually those builds end up taking so long to get on the street people get bored with it. Which leads to lack of progress, stagnation, part outs, and selling the car "almost finished" for half what you have in it. That is what I want to avoid. Realistically I don't have an unlimited budget or unlimited time to finish it. I have a house payment, work, school, and family that come before the car. I have 5,700 car fund. I can sell off some old DSM/Mustang parts to get a bit more. The rest will have to come as I do the project. But the main thing is that doesn't turn into a 2 years fix everything wrong with the car all at once project. I never can finish them due to boredom. I think for some mechanics it is a bit harder to be excited to work on them as we do it all day at work.

On a side note, pretty sure there was a 201x$ GRM challenge V8 Miata... So it is doable. It depends on what kind of corners you cut. I am not willing to cut things that could lead to catastrophic engine failure such as oiling, timing, cooling. But I am willing to find some part at a good price to make it work in many cases.

 

Absolutely it can be done and there is a build happening right here right now that is headed to the 2014 GRM challenge. I'm just trying to set realistic expectations so when the double whammy of builders fatigue and credit card fatigue hits you don't get so discouraged you chuck the whole deal. Sounds like you are well aware of the situation and you have that on your side. If you have not watched Gabriel's videos start to finish you should. It is really fascinating to see how he goes from extreme highs to extreme lows in the process. I've never seen the reality of the process spelled out so well as he did in his videos.

Just to be clear no one here is trying to talk you out of doing the build. You clearly have the chops, desire and common sense to do it. And no question the world will be a better place with another V8 Miata in it. We don't mean to pick at you we just want use the school of hard knocks we went through to do everything we can to see you succeed.

 

New topic...

I noticed your radiator is listed as unknown. I don't know if it would work in an RX but if you do build the NA I found this works really well for a radiator:
http://www.summitracing.com/parts/GRI-8-00009-LS/

It's a late 60s early 70s Chevelle swap radiator and I figure if it can keep a 4000 lb tank cool it should do fine in our cars. I ran an autocross last weekend in very hot and humid conditions and it did great.

I used an ebay fan that is about the same as this $35 hurricane maker


It just dawned on my this radiator and fan is not in my build sheet because the one I ran last year would not keep it cool. That falls into both the school of hard knocks and the Oh S--- category...

 

First as far as the looks go: you'll be looking at the interior of the car more than the exterior once its done. I would not spend time in a car I can't stand staring at the dash board of.

Cost: The builds you've seen for sale in the $10K to $16K realm I think were most likely Ford builds. LSx builds sell for more. I saw a Flyin' Miata build go for $50k something.

You could build a quality street car for under $12k if you went with the Ford kit. I have a street/track Ford build that keeps up with Corvettes. I just did my rebuild cost sheet over again and the entire car is still under $16K including the donor car, hardtop, suspension, brake upgrades, MegaSquirt, netbook to tune it, roll bar, door bars, track seats/belts, two sets of wheels and even my track trailer. The only things I didn't count in that total are brake pads, tires, oil and filters or anything else that has been replaced due to wear.

I know that Ford builds are often poo-poo'd as being old/heavy/underpowered/etc. I really believe thought that they are still a very relevant alternative to the LSx and that their only real short coming when compared apples to apples is a few MPG's of fuel economy. I believe that too can be equalized when I can get mine running on a properly tuned MS3 with sequential injection and maybe even some type of cylinder deactivation.

Here's a video of my Miata being propelled around a track by an old, underpowered, front-end heavy Ford 5.4 liter:


Good luck with your build regardless of how you decide to go,

-Jason

 

Jim S. You have no idea how much that means. I've followed your build for a long time dreaming of when I could swap my miata. It seems impatience and and wanting to go more aggresive will get the better of me and I will probably just do the RX7. If I had 10-15k to through at it saved, I would just plow ahead with a pullout and rx7 chassis. However I do not, and have been planning the way I would do it with either car for 2 months now.

I considered a ford build because you can realistcally find 5.0 H.O.s for 50-150$ around here. Hell I have seen 120-160k mile ford explores with the GT40P head engines for under 2000$. I just don't think I would be as happy with that. I am not a "Ferds sucks" guy but I am a GM guy. Every car that I have ever owned was either a GM, Toyota, or Mazda (RX7,Miata). With the exception of a stint of DSM ownership to which I say, they are great toys, but aweful as your sole mode of transportation.

Will probably do the build thread here and on NoRotors when I get to that point. Side note, I was able to find a nice running RX7 Hardtop with 90k on the clock for 3 grand. Or a nicer body with blown coolant seals for 1200. So hard to choose on that.

 

Cool beans!

 

Well found my rx7. Looks like the wife and I will be going to Gulfport MS for an overnighter to pickup a SBC 350 /700R4 combo 90 model for 2900$. Runs and drives. So it will save me a good bit of money on some of the hardparts for the LS1 swap. Also should be able to sell some of the junk on it off to make back some cash.

Has a stupid cowl hood (needed to clear air cleaner on TBI or Carbed cars), big ugly speaker box, and some pioneers in the trunk. Will probably keep the engine/trans combo and swap them in our truck then sell the SBC and 4l60 in the truck.

Crappy pics.