1992 Street/Autox/Track car
 

Hello,

Wanted to start documenting my car now that it's not quite stock anymore. I ran it for the last few years as an STS autox car and for many track events. Once it became painfully apparent that my motor was down on compression I put something together using a bunch of hand-me-down parts from friends. Not chasing any big power goals or class wins, just hoping to keep the car fun and reliable. I've only done a couple events on the new engine, and need to continue to adjust the setup and my driving style for >100hp.

Engine
BP05 with stock internals
MP62 supercharger, 1.9 pulley ratio
Beer Money Motorsports ECU
??? header, might be Jackson racing
3" intake
75mm throttle body
ebay catch can
900cc FlowForce injectors
DW200 fuel pump
19" Borla XS muffler, Vibrant Ultra Quiet Resonator, catless

Cooling
ebay aluminum radiator
11x11 EMUSA intercooler with 2" piping
M tuned coolant reroute
Singular hood vents
ducted and sealed radiator & IC

Drivetrain
5 speed trans
4.1 Type 1 Torsen
Poly engine mounts, poly diff mount inserts

Suspension
Whitener revalved Bilsteins
800/500 springs
Racing Beat Race front bar
stock rear say bar
supermiata 863 bushings
brofab front hubs

Brakes
BX11 supermiata front brake it
1.6 rear brakes
Master cylinder brace
Steel lines

Feel free to ask questions/tell me why my build is wrong.

https://cimg5.ibsrv.net/gimg/www.mia...b9b462235e.jpg
https://cimg6.ibsrv.net/gimg/www.mia...2845c9772a.jpg

Sounds like a fun build, how have you liked the BMM ecu? I haven't seen many people with them.

This is my first time working with a standalone ECU, so I don't have much point of reference. But overall the featureset seems fairly robust - better than a MS2 at the same price, and the firmware is still having new features added with ongoing development.

Few updates on my car. I have now done several hundred street miles, 2 track days, and an autocross on the new engine. Still sorting out minor issues, but the motor hasn't exploded, overall a great success.

I just converted the fueling from batch to sequential. I used an NA8 injector subharness, swapped to a NA8 ECU coolant sensor, changed the connector on the main harness from a 6 pin to an 8 pin and run 2 wires to the ECU for INJ 3&4. A bit more work than just splicing into the existing wiring, but the install is very clean. The switch over to sequential fuel was a massive improvement. Idle is so much better than before, and the car is far smoother at low load. I'd recommend anyone with a 1.6 chassis and large injectors to switch over to sequential fueling ASAP.

Other change was changing the front pads from EBC SR-21 to Hawk ER1. The EBC had way too much bite for my setup, making corner entry awful. The Hawks still might have a little more front bias than I want, but the balance is now significantly better. Once I get around to installing a bias valve that could help.

Installed hood louvers. They seemed to help as coolant temps were about 210 on track vs 225 last time I had the car out.
https://cimg1.ibsrv.net/gimg/www.mia...ae38f571a0.jpg

Love to see a tracked F/I miata! Nice car, love the vents.

Looks like Palmer CC. If so, great track. How was the tune?

Correct, Palmer CCW.
The tune is still conservative. A bit on the rich side for safety and only 6-7 psi of boost. Despite that, it feels good, especially compared to the tired 1.6 I had last year.

On the non engine side of things, I lost a power steering belt and pivot bolt in the first session, and need to fix that. Halfway through the day I reconnected my rear sway bar and set the front to stiff, which solved an understeer characteristic that I was fighting in the morning.

Brought the car to a drag strip - something I've never done before. With driver it weighed in at 2400, which puts my estimated hp at 175. About what I expected, but less than I hoped. Still plenty of optimization on my current setup that should help improve things.
https://cimg2.ibsrv.net/gimg/www.mia...c1b865b767.jpg

Bunch of projects going on for the winter. My factory rubber bushings became self-extracting so I replaced them with the Supermiata 863 kit and refinished the control arms while I was at it. My front hubs have been flawless for 50+ track hours, but got BroFabs for safety. Also finally resolved the "hot air intake" my car used to have with some under-hood ducting and a NACA duct.

https://cimg2.ibsrv.net/gimg/www.mia...e25b819fab.jpg
https://cimg1.ibsrv.net/gimg/www.mia...3053a88910.jpg

Nice updates! And honestly not a bad time/mph for the 1.6 on the little mp45! Good call on the hubs, I just went the same route for safety.

Nice build. BMM is gonna need its own misspelled section here soon.

... well it's a 1.8 with an MP62.
But honestly the power is right about where I would expect. Running 1.5 bar of boost on a 115whp stock motor should put it around 170hp, which is exactly what the drag times supported. This was also running a very conservative ignition map. I'm currently adding a crank angle sensor, knock sensor, and pulley swapping to get 9-10psi. That should make a safe 200hp for next year.

I put together a intercooler/radiator duct. The slope is steeper than I would have liked, but I was limited by my IC mounting and the factory bumper. My CLT wasn't an issue, but hopefully this help pull IATs down.
https://cimg7.ibsrv.net/gimg/www.mia...f8e7aecafe.jpg

https://cimg4.ibsrv.net/gimg/www.mia...3881b17164.jpg

What pulleys are you going with?

I'm using what I already have sitting around, so that would be a 110 and 58 for a 1.9 ratio. If I encounter belt slip due to the small sizes, I might go with a 120 or 125 crank with my current 65mm snout.

My 120/65 is producing close to 13psi. It'd be nice to meet up at a track day to compare cars and tunes someday. My aggressive, though reduce from the crazy max ign advance, is now looking like the following. Only haven't logged it yet. Down 2 degrees from log that had one knock spike at 6500. Just offering it up since the set up is similar. Will be interesting to see what your knock sensor shows as you advance ign.

Thanks for the info.

Yes, it would be cool to meet on track. I didn't plan too many days ahead of time, so that I didn't need to be rushed to get the car ready like last year.

Quote got screwed up on the original post here.

I need to do some ducting like yours, seems like it would make a world of difference.

Any concern over the breather filter on the VC saturating with oil and leaking onto the exhaust manifold? I've got the same setup but am planning to change it up this weekend.

I’ve run this setup for about 5 track days and 5 autocrosses without issue. It was just the quickest solution while I was rushing this build together. That said, I don’t love this design, and want to design a Venturi system that will provide vacuum source while in boost.