My twin supercharged tbi 350 miata build

[Shawn1989]

let me catch everyone up on this.

over the past 2 years, i had been swapping a chevy 350 into a mazda miata [funds held me back, but eventually i got it done]..... caught fire in the process but it didn't stop me. i blew the engine up at the racetrack, rebuilt it, and now were are back in action with a different chassis.

SO, after slight research and talking with Dave W; i am going to be building a twin eaton m90 [thunderbird supercoupe superchargers] tbi chevy 350. The plans are to port them and if calculated correctly; should run about 18PSI. i will be running a single 2in-1out intercooler, a methonal/water injection system when the car hits boost, and e85 to TRY to prevent detonation on a 10:1 engine. chevy 350's are a dime a dozen at my pic-a-part....... so, if it blows, just gonna keep trying until we get it straightened out.

ill be running a 454 throttle body with 454 injectors, i am also running a twin belt setup..... v-belt for crank, waterpump, and power steering; then a 5-rib belt found on early vans for the alternator, waterpump, crank, and both superchargers...... i have 2 timing belt idlers from my miata that i am using for the non-ribbed side as idlers to get the belt to go where i want, then im using a tensioner somehow to obviously put tension on the belt. the superchargers have 8 rib pulleys, but the 5 rib belt fits right over them no probelm.

the engine itself is a GMPP crate 350/285-300hp...... i slapped vortec heads on during the rebuild and the shortblock is the exact same as the GMPP crate 350/330hp, so theoretically it should be the GMPP crate 350/330hp now. It's an 880 block with 4 bolt main and 1 piece RMS. The car already blows off the tires through 4th gear, but still, power is power :D time to grab some slicks lol.

The trans is a bone stock WC t5 from a v6-fbody. it's held up so far, no issues...... stock 10.5in clutch.

rear end is a stock miata 4.10 [7inch ring gear]...... it will be upgraded to a 2.8 thunderbird IRS rear with factory five racing axles, however, im going to have to relocate my lower shock mount for the axles to fit.

custom driveshaft.
custom TBI wiring.... re-worked my harness on here awhile back
PCM - 16196395 - pretty sure dave and i talked about this computer being capable of boost...... can someone please clarify?

there is a LONG road ahead, but it will all be worth it. I am shooting for 450whp.

this is my car after 2 years













but i needed to get something safer, so i am building a different chassis with a roll cage; just in case.

in the meantime. enjoy
https://www.youtube.com/watch?v=4ZvIvqdXKoI

https://www.youtube.com/watch?v=XDSE2km69F8






I started building and eventually finished the trans tunnel...... don't hate on the flux core welder haha. It does the job, just ALOT of cleanup.















I also tac welded plates in the driver compartment on the firewall to patch the wholes that I won't be using.





far from perfect, but far from bad too. think im done with the underside..... i know there's imperfections but its good enough for now.... i can always give it some love later on.

[Engine07]

Man that's going to be a sweet build!! Great work so far, that's going to be a fun little toy. Just be careful with slicks on the rear axle...you prob already know but that thing will be a grenade waiting to go off when it starts hooking up. I've been through a few on my toy, lol. I love the E-85 for high octane also, that's what mine is running on. Just watch your tuning different times of the season as if you buy it at the fuel pumps it changes actual alcohol percent with season changes of the year so some tuning for different times of the year will be required especially with forced induction. My toy runs on a carb though with nitrous so it might be a hair more sensitive to change that superchargers. Just make sure you get the tensioner set tight with the 5 rib belt so they don't spin on ya under boost. Can't wait to see how it turns out

[Shawn1989]

God gave me a gift at the junkyard today.






now I just need 1 more lol

oh yeah dave, there is a vacuum bypass on the inlet of the blower

[Shawn1989]

Grabbed the handy dandy angle grinder and cut some square tubing to make a tensioner bracket; then drilled some holes for the tensioner to fit. Came out pretty good.

Going to weld a nut on the backside to hold it all together.

As for mounting it, I'm going to weld it to the sbc adjustable alternator bracket. Shouldn't be an issue because the audi alternator I'm using is fixed; so that bracket is just there for support of the alternator and idler.

[Shawn1989]

Ran to Home Depot to grab a piece of stock so I can start making mounts for the chargers.
Hooked it up in the vice and began bending..... The result:






I still need to drill holes where it sits on the exhaust manifold.



After that I grabbed an old miata front sway bar; chopped the ends off and they fit perfectly on the heads.









Then I grabbed 1/4 steel and began chopping what the Chargers will actually sit on..... I need to make a duplicate:



For now, that's it; there should be an update tonight. Got a few gussets to cut and quite a few holes to drill, then I need to start lining everything up and tac/welding everything together.


I also am going to make a plate that will mount to 2 bolts on each of the Chargers snouts to hold them together

[tedjan]

keep updating.nice work

[Robban_C]

... After that I grabbed an old miata front sway bar; chopped the ends off and they fit perfectly on the heads. ...

I haven´t had time to read the whole thread yet so I might be missing some information.
Are you planning on welding on an old sway bar?
I like the idea of using what you already have but you should NEVER use a sway bar (or spring) for something that should be welded. They are hardened and tempered and might crack after welding. Maybe not immediately but sooner or later that might happen. Steel that are made for springs (a sway bar is kind of a spring and uses the same material) are not considered weldable and that is just because they are prone to cracking. You can easily weld in them but they will usually become very brittle after welding.

What usually works if you have to is soldering/brazing (I don´t know which is the right term) with high temperature silver solder but that would involve a lot of heat with a gas welder with such big parts as this. It´s not that practical.
In this case I would fabricate the parts in weldable steel instead.

But I really like the idea of a Ch SB in a Miata, even without the blowers.
The blowers will make a ride in your Miata like riding bareback on a natural aspirated Ch SB. LOL!