'94 SR20T25 Turbo Miata
 

Hey everyone! Over the next few weeks I will be embarking in my first turbo build (don't give me too much credit a shop is doing most the work) so I wanted to have a place to document my progress and ask any questions without flooding the boards with new threads.

Background: About a 2 years ago i bought a 2013 Scion FRS which opened my eyes up to the joys of a lightweight nimble cars. The problem was every mod i wanted to do to the car was breaking the bank. Pretty much everything was going to cost me ~1000 per upgrade and it got me thinking, maybe I don't need a new expensive car to mod, maybe I should give this miata thing a try. So that's what I did. I put my sweet new supercharged FRS for sale and went looking for a cheap little NA miata.

FRS:
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After selling the FRS I bought my first miata. It was a modded 96 with a maacco paint job and stripped interior.

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I loved the car and used it to get into autox and I was hooked. I attended every autox event this year and thought the car was a blast to drive. The problem was I hated the aesthetics of the car and how aged it was. It was on its second engine and had about 200k on the dinged up body.

That is when I found my current miata. I found this car 10 hours after it was posted on craigslist. It was a bone stock 94 with 50k miles and 1 owner.

Day of purchase:

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I spent the next week swapping over the parts I wanted to keep and then put the 96 up for sale. I brought over the wheels, tein flex coilovers, racing beat tubular front sway bar, and nb2 seats I had purchased. I changed all the fluids, bought a nardi wheel, a motiv shift knob and a hard top to top her off. Thats where she sits today.

Current miata:

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I have loved racing the miata in the str class but now that the season is over and I have learned a ton I started to miss having power. So that brings us to today. I did a ton of research on turbo miatas and finally bit the bullet on a used kit. Here is a list of parts I got.

FM Manifold/2.5" Downpipe
Trackspeed Engineering 10MM inconel studs with locking hardware installed
FM 2.5" downpipe trans tunnel brace
FM Silicone intercooler piping
FM turbo intake
Turbosmart recirculating valve
Ebay Intercooler (has a dented tube from a something hitting it, but is only cosmetic.)
SR20 T25 rebuilt before installation with new 7psi Garrett wastegate
FM turbo heatshield
ACT Clutch
Fidanza Flywheel
RX7 Injectors
MSPNP2 by Brain

Which arrived today!!

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Well that's my intro. I will use the rest of the thread to ask questions and post updates. I would love some advice from everyone as this is my first build and dont want to repeat mistakes others have made.

Misleading title is misleading.

Expected an SR20 engine install.

C

Yeah. I was prepared for major failure, but this should be okay!

X2, disappointed.

I thought that when making it, sorry about that..... I'll make it more clear

Where in PA

Downingtown, based on horse and buggy i assume you arent far?

Wow 4 months later but it's done!! Pics to come after I wash off all the dust. Here is the important part. 217whp/227wtq at 14psi

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I seriously miss my old 94 with my SR20 t25 setup. That dyno is just about perfect for a street car.

This makes me very excite, because I've been worried that a non-99/vvt head on a 1.8 swap would be fail boat. But those are pretty good numbers.

Anything done to the head? Porting? Intake manifold mods? Stock throttle body?

Everything is stock outside of the parts listed in the first post. Conservative tune and there is some power still on the table. Since my main purpose is autox i dont think I want anymore power though.

I cant wait till it gets warmer. Its hard to enjoy it with the cold weather. 0 traction in 1st-2nd

You have also created a tickle in my pickle. My setup is similar minus the displacement so naturally the dyno looks like my 1.6 except elevated 40 digits and more fun in low rpms. This is what I expect with my 1.8 swap this spring. Vids needed!

It's bittersweet though because you lose some of the acceleration the cold air brings. It's noticeable on a hot day.

Very true, I will try to bring out the go bro when we get a halfway decent day

Not sure how I missed the thread but that was a gorgeous FRS.

that it was..... :( Having way more fun with the miata though

Congrats on the very nice results. The torque curve looks like it will be a blast around town.

Nice. I put down 225 on a similar setup a few years ago so your #'s are spot on.

PS love the FRS, I DD a BRZ

yeah i love the power, could work on the top end though.

the cool thing about t25's is you can slap in a 2560 or 2860 and retain everything else, and voila - instant topend gains without giving up almost any of the lowend. win/win

yeah 2560 is coming once I am used to this power

Coolant Reroute and 949 stage 1 brake kit installed with carbotech ax6 pads. FM butterfly brace and miataroadster shifter on order. Too bad everything is on back order....

Oh and hard top in storage!

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I also wish to echo the beauty that was your FRS. The Miater looks really nice though, and those are really strong numbers. Must be a total blast to drive.

Dont make me regret my decision!

I just bought a BRZ and the torque dip kills all street enjoyment for me. What did you think of it before you supercharged your FRS?

Just always drive above 4k rpms :P also a good header and tune will help the dip issues

That torque curve almost makes me think an NA 1.8 head wouldn't be the worst thing in the world. Nice build so far, very similar to what I am planning.

Thanks, we will see how it handles the first autox on saturday. I will have videos

Subscribed, and holding you to that.

So for some reason mother nature decided we needed a blizzard.... Event cancelled. Theres another event next weekend though so we will have video then.

Where's the next event you're talking about? I'm in the Lehigh Valley and have been looking for something to checkout.

Sweet. Setup is very similar to what I am working on. Looking forward to when I am dyno-tuned in May and I will ping you so we can compare ;) I will only be having it tuned to wastegate limit though for le safety :(

If you have a standalone ECU and big enough injectors, there is no reason to run the SR20 T25 at only wastegate for safety. You can push 15psi with it and a decent tune and not blow up the motor. It will peak around 225ft/lbs of torque no matter how much boost you give it, then fall drastically once past 5k rpms.

Sorry for threadjack, OP.

@shuiend: I will be using a dieselmiata built DIYPNP and rx8 injectors. I worry about running past wastegate because I plan on building my car for HPDE. I need to make sure it can handle 20 minute sessions in Midwest summers. Will you statement still hold true then?

I would get on a dyno and do a good number of runs. See what power differences you make going from 10-12-15psi. The SR20 T25 just starts blowing hot air around 12-14psi and you will probably find that you don't make to much more power above that. I know way back in 2008 or so at a MT.net dyno day I did a few runs with spikes up to 16-18psi I believe and realized more boost was not making much more power. For track use in a hot environment I would probably stick to 10-12psi just to keep intake temps down.

If you are on the dyno, I would tune higher, then just turn down boost for the track.

OP Delivers. Here are my runs at Hershey Park autox. Sadly I am now slower than I was before I turbo'd. Could be a ton of things, lack of skill, soft spring rates, 205 tires, lack of skill.... Still had a blast and was way more fun than N/A

interior view of my wife and my best runs from today and last week. The wheel shot is the same as last week.

Lookin solid man. What are you running for suspension/tires?

Wheels are 15x8 konig wide opens with 205 bfg rivals and suspension is 7/6 tein flex. I am upgrading to 700/400 xidas and 225 tires this month though.

I have been having a ton of fun but am having trouble getting the power down at the autox. Currently I have running a RB front sway bar, stock rear, 15x8 +20 wheels on 205 BFG rivals. Is there anyone following this with a similar setup that has some advice?

Is 220 trq too much for a 205 street tire or do I just need to learn to use them? I am getting spanked by the STS guys. Is it worth going up to a 225 street tire or will it not make a huge difference unless I make the jump to R Comps?

Might help if you ditch the rear bar.

Also, 225s won't fit worth a darn on those +20 wheels you've got. Go with a x8 +32 or x9 +36.

225s will be better, R comps better still. But with that amount of torque you'll still be able to rotate the car at will. Probably just need to work on driving smoother.

Yeah, I loved my wheels until I read more about proper offset and now I hate them haha. I didnt think I wanted R comps since I daily the car and drive to the course but it seems the next step is to get a dedicated track setup. Either that or I sell my current setup to cut some cost on a permanent 15x9 225 street/autox setup. Decisions decisions....

Thanks for the input

My car is useless at autox. Last week I drove a tight/short course and did "okay" but I drove my buddies NB with stock VVT engine, torsen, 15x9 w/ rs3's, and 500/350 springs and stock sways & managed to beat my own time.

I am on 15x9 with 225 rivals...but the tires aren't the issue

Issue 1) 700/400 xida's. Fantastic on the track,WAY too stiff for autox
Issue 2) Slightly larger than stock rear sway
Issue 3) ... a big one... 11.75 BBK with DTC-60's are on/off when cold. I struggle to find the threshold without locking up.

Long story short going to 15x9 is a very good call, but be aware there could be other changes that would greatly improve your car at autox. Street vs Autox vs Track are 3 very different car setups.

My friend is doing great on 700/400 konis. I am hoping the xidas will work out since it is a huge investment haha. Emilio recommended the 700/400 for strictly autox. I wont be going BBK for a while so im good there. I may try removing my rear bar also to see if that helps.

Big courses or small tight shit? Dampening settings make a huge difference too. I tend to play with them quite a bit depending on the course.

umm about 45-50 secs with a few slaloms, a sweeper then 1 or 2 extras like a chicago box or wide slalom. rarely hairpins though

Not many updates. Xidas got pushed back until june...... Doing some fine tuning tomorrow and had some small repairs dont last week to the front bumper. Here she is all done up.

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