Hi guys!

I'm helping a friend build his 94' Miata. I've never messed around with Mazda but have built quite a few Nissan/Infiniti/Chevy/Ford boosted cars, that's how I got roped into this project haha! Anyway I would love any help and advice from you guys that have had experience NA or turbo that might speed me along with the build. The car currently is a stock 1.8l, 5spd, with MS2PNP with a bad base tune. We found metal in the oil not long after he bought it so I told him I would help him do a swap with something more current.

Parts ordered:
I ordered a JDM VVT 1.8l with matching 5 speed. (we pulled the trans and the clutch and surfaces are BRAND new shape!!!)

Parts I have:
Megasquirt 2 PNP

Stuff I'm not sure about yet:
Injectors from VVT flow rate

He is on a pretty tight budget so I'm trying to get it done as cheap as possible. I am eyeballing the MS3 Pro Mini for $675 including 8' open harness or the Maxxecu mini $765 since the MS2 won't do everything we want it to. The plan is getting it going NA and when he builds up a few more $$$'s add 5-8psi to it.

 

Welcome. I'd just keep the MS2 until he can afford something nicer. Buying one of the cheaper wire-in ECUs ends up being a lot more work and money building a harness than just buying a pnp ECU. Injectors are 265cc, good enough for naturally aspirated build, but not anything else.

 

Welcome! Looks like a great project, its good to see the older cars getting some love!

You'll find the build threads useful, and if turboing is on the horizon check out some of the stickies. Be warned though, while doable, low budget and turbo are uncomfortable bedfellows. In particular, the 5-speed is not a great fit with turbo torque nor are the stock BP rods.. Your friend's plan to build the atmo engine, and drive it for a while while getting a solid budget together for the next step is a good one, and building a low boost turbo will protect the gearbox and rods. But boost/power is addictive ...

A rebuild of the removed engine would be a good start for a higher HP build, as it could be build with the necessary good bits to handle the turbo demands - if that engine is not too badly damaged.

 

I'm not sure what shape the original engine is in but when I see metal chunks I know it's going to be a complete rebuild. Most of the machine shops around here have a hit and miss reputation of getting things right so I'll usually find something that hasn't blown chunks to rebuild or just buy a low mile unit.

Money for the ECU isn't an issue if we sell most of the things we don't need. I figured if I have to spend the time learning a new type of ECU I might as well do it on a newer version that supports vvt and has better tables from the start. I have used quite a few different tuning platforms and have wired in standalone ecu's before so it shouldn't be too difficult to get one in there. Also we aren't shooting for very much whp, the 140-180 range would be the most I would feel comfortable with. I was going to stick with the MS2pnp that's in the car but I have read a few people having weird problems and also the VVT side isn't supported. But like I said I have no experience with Megasquirt so I'm trying to gather as much info as I can so I don't make too many mistakes

Thanks for the injector info, 265cc are pretty small. I'll have to do a calculation with the fuel type we decide to use and see if we want to upgrade them too. I also built a fuel injector flow bench years ago and might flow match them at 3 and 4 bar to verify that they are in good shape in case we use them.

 

I ordered the Megasquirt 3 Pro Mini with 8' harness today. I also bought a used throttle body from ebay because the engine got whacked in shipping and bent the throttle cable assembly. I am going to use GT500 fuel injectors since I have several sets in the shop. I use them in my turbo sonic, G20 and G35x turbo cars and they have always done me well. I'm going to change some gaskets and replace the timing belt with a new Gates brand before we put it in the car. They all look new but I don't trust a 20 year old rubber

 

I just got the AMP MS3Pro Mini with wiring in. It was right at $700 shipped with the 8' harness, Tuner Studio license, Serial link cable, and usb adapter. I'll probably make a separate write up on the wiring details since nobody talks about using this hidden gem. The old MS2PNP that was in the car is a microsquirt that was originally designed for powersports and also as a standalone transmission controller. I just wanted to start with something a lot newer with VVT capability and flex fuel since we will be using E85. I also wanted to keep all of his dash gauges working (Speedo,Tach,Gas,Oil press,Water Temp). I have already figured all of the gauge wiring and found out why his oil pressure never worked since he bought the car. Someone swapped the motor with a 95+ and never changed the oil pressure sending unit. So it has the dummy switch instead of the ohm based variable pressure sending unit. I about choked when I saw what those pressure sending units were selling for and refuse to pay $60 for a crusty used one or $160 for a new one. I have a few cheap options on the way that should be REAL close so I'll write something up on that when they are tested. I'm trying to keep it with the same 1/8" BPT thread and ohm value as close as possible.

So it's real nice the 1994 gauges are independent. I won't need the factory ECU to keep all of the factory gauges working. The water temp on the 94' has a 1 pin blade sensor for the gauge and the VVT motor has the hole blocked off with an allen. So I just need to take out the allen and put in the sensor. The other water jacket sensors (94' 2 pin & VVT 3 pin) are for the ECU, I'll pull that and tap it for the GM water temp NPT. The oil pressure sensor is just one wire and grounded to the engine block. And from what I have found it's about 52ohms @ 0psi and 16ohms @ 90psi. The VVT transmission has a digital speed sensor that can be removed and the 94' manual cable assembly bolts right in so the speedo is good. Gas gauge needs nothing done to work. Tach will come from the MS3 spare injector output. All of the other factory EFI wiring will probably be deleted after we get it all running. I just need to keep the grounds, coolant wire, and oil pressure wire.

 

Since no one has posted it yet: https://www.miataturbo.net/engine-pe...athread-80469/

You might find some useful tidbits there. I ran my NA on track with a VVT 1.8 on MS3 for almost 7 years... it's a great setup, very reliable and pretty quick. Adding a turbo will decrease the former, but greatly increase the latter.

 

I got in some more hours researching miata stuff. I found a very small crack in the oil pan, it looked like they sat it down on a bolt or something. I decided to use a torch to get it melty and use aluminum rod on it. I also coated it in JB weld just in case there were any pin holes. I tapped the pan 1/2 NPT and used a 5/8" barb so it will be turbo ready. I didn't like any of the options to make the GT500 injectors for properly and I wasn't going to break off the plastic oring retainer. I also don't like isolators on the bottom side for sealing. I ended up turning some oring bungs for the lower side and miling the 2005 fuel rail cups down just past the nubs and inserting Honda oring bung adapters. The factory rail will now fit with stock spacers, bolts, and stock unmodified GT500 injectors. I did this in case he wanted to swap to larger ones later. The engine also got new front and rear main seals and some gaskets to button it up. We are going to drop it in the car this Saturday.

 

We got the engine/trans in the car Saturday. I'm still finishing up the 01-05 fuel rail and GT500 setup. I also started cutting connectors off of the harness for the Cam,Crank,TPS,IAC,CTS,VVT,Coils,and Injectors.

 

Any concern with the JDM 1.8vvt motor being 10.5:1 compression ratio for boost?

 

Nope, wouldn't mind if they were 11:5 actually. E85 works better the higher compression that you have. Now if we were going with gas we would have to take a bunch of timing out.

Also I have decided to take the extra time and tune the car for him. I ordered a tunernerd knock monitor v4 setup yesterday so I can get a reliable timing map worked out. I was going to send him to a tuner but I figured I might as well learn MS3 since it may be the next option for my turbo foxbody down the road.

 

Still a work in progress but I am about done with the 01-05 rail fitted for GT500 injectors. The top side of the injectors I milled the stock rail down just past the clocking nubs and used honda to standard oring adapters. The bottom side (head) I used GM LS injector adapters, drilled and turned them down and then I used ultra grey rtv to seal them into the head. I also used a NPT tap on the return side of the fuel rail so I could use a 90 degree barb. I used to do this on Nissan/Infiniti rails to get rid of the factory fuel regulators. The main reason I'm doing this is because I don't like isolators and want Orings at the bottom so there is no chance of Vac/Boost leaks. If everything works right I'll make a how to thread with measurements. I think I have $30 in parts invested so far but don't ask how many hours invested haha!

 

What do you plan on regulating with? Why not just get one of the proven Flow Force's kits?

 

I'm using an areomotive 1:1 knock off regulator. I wanted it to be adjustable in case I ever decide I need more injector and want to push more base FP. I've used them in a bunch of infiniti boost builds. I really didn't want to spend a bunch of money, I had 3 sets of GT500's in the shop (bought them before the price went up) and only needed the aluminum adapters and a 90 degree barb to make it work. Also I'm a cheapskate and like to make stuff work that I have I could have made the adapters but it actually would have cost me more and took a bunch more time.

The forceflow kit is $330 and still uses the isolator bottoms. (I'm just not a big fan of them) then you need a 99-00 rail $100 and a 1.6l regulator $20.

I used a set of GT500s $150, regulator with lines and gauge $38, Brass 90 barb $5, aluminum adapters $20. And a crap load of time haha.

On a side note I just pumped them up to 90psi today and it looks like they hold pressure. I'll get the fuel regulator and lines hooked up and see how everything works.

 

I worked on fuel system plumbing today. Used steel braided line and the 1:1 regulator. I also got the wiring figured out from the ecu connectors to integrate into the MS3pro mini harness. I powered up the fuel pump and set the regulator to 43ish psi. I'll hook up a digital gauge to set the final pressure exactly so I can match it in the ecu.

Edit: I also put a flex sensor on the return sitting up there by the shock tower. I'm going to tune it on gas first and then use blending when we go E85.

I also deleted the vacuum butterfly setup. I JB welded the outter hole and used RTV on the internal shaft holes.

 

Please be sure you’re not clamping -6 hose to any 5/16 barb or any SAE line, like the flex sensor.

 

I did, but have done it like that for the last 10 years. The return has virtually no pressure. The high side is all barbed.

Edit: I did on the flex sensor, the barbs are all correct size.

 

I just got the Knock Monitor Pro V4 yesterday. I had no idea they came out of Jamaica, I ended up having to pay import fee's before they would deliver it to my door. Lucky it was only about $25 so it wasn't a big deal. I'm real curious how this thing holds up against my Phormula KS4 pro setup. If I can have the car long enough I may get to test both knock setups on this build.

I'll probably 3D print a ABS mount to hold it since they don't include any type of assembly to hold it in your car.

 

We finally got it to a point that was safe to try and start it up. It fired right up and I didn't screw anything up yet. We warmed it up and toped off the fluids and checked for leaks. Now I can take some of it apart and clean up the wiring and wrap it all up. I'm surprised the base tune I threw together ran as good as it did, hopefully we get her tuned out soon. It's not going to be fun unless I figure out his heater problem because it's 24 degrees outside today haha!

Made a video of it starting up

 

Sweet! I've never heard of the knock monitor pro before. Be sure to give us a good review on it when you get to use it! Nice work on the first start, that is always a monumental moment in any build!!