I’m building a TT3 focused na miat out of my Champcar endurance racer. I had a good time endurance racing but running a team by myself was tough. I took the car to a track day in 2020 to see if I wanted to just do TT and the event director allowed me to run in HPDE4 to get evaluated for my TT sign off. I had a blast and decided that was the direction I was going to go. I also blew up the motor when the alternator mount broke off the water pump housing and it overheated.

Well the car has been off the track since for all the stupid reasons since then. While it has been down it has gotten many upgrades. Some of the big ones are a VVT swap, MS3Pro EVO ecu and an AiM data logger/dash. It’s almost back together finally and I’m hoping to get it dyno’d and to a track day before the end of the year.

Ok enough bullshit and the reason I'm here: I'm going turbo! I’ve got a couple vvt short blocks around. A blown jdm one cause I’m stupid, a low vacuum US spec and two more jdms. I had a buddy who imported a bunch of them and got a deal or two. I'll start with the blown block obviously I’m going to over build a motor to support the 240ish hp I’ll need for TT3 and up to the 400hp I would need for TT1. For the turbo I’m leaning towards a Kraken top mount kit with a 6258 but I’m tempted to get a 6758 so if I wanted to have a TT2 or even a TT1 tune I could have those on hand and wouldn’t be over running the 6258. The miat isn’t the best platform for TT1 from what I've been reading though. I would really like to be competitive in TT3. TT2/1 would be more for fun and extra track time. So rods, pistons, studs, etc. I’m not too concerned with the motor build. I really am looking for help with the turbo setup. Turbo size, intercooler size, all that.

I’ve run into some other technical issues with alignment setup but I’ll bring that up later when I beg for help with that.

 

Nice! Nothing like a turbo track miata, you are in the right place.

 

Heat, plan for excessive heat generation, scour and implement all the cooling threads on here.
Your collection of blocks will prove useful as you work to overcome heat.

Brakes, plan for excessive heat ... I thought I might not need a bbk with my turbo race Miata, just ducting and replacing parts more often. Yeah, no! All the wisdom here is correct on bbk.

 

There is a great ladder/progression system in NASA TT and a boosted/swapped Miata can win/compete decently in TT5 and 4. TT3 will be fun to watch, but even some of the wild unlimited class TA cars with 2x the power barely put down mid pack TT3 times.
A 10:1 weight: power Miata in TT3 would be roughly 2400lbs and 250whp after modifiers.
A 12:1 weight: power Miata in TT4 would be 2400lbs and 210whp after modifiers. Both assuming 245 Hoosiers.

A 6258 will need detuned heavily for 4, and very easily turned up for fun in 3, even 2.

As far as You may want to move that down one step on the ladder.

At my local track(Mid Ohio) the ST3/TT3 records are 1:30/1:31
Gridlife Unlimited/Limited Miata chassis lap records in 400-450whp turbo K24 and LS cars are 1:31.6/1:33.3
My n/a k24z3 xT5 car with the ballast out did a 35.0 in TT4 spec last month on 225 hoosier scrubs and a small 3" Gridlife GLTC splitter. NASA xT4 allows a 6" splitter. So there is tons of time on the table for me to faster in 4 spec with class-max aero and bigger(fresh) tires.

Keeping the power goal more modest would keep you in TT4 and still allow all the big fun aero and keep the class pace more achievable.
Also, running a fresh 4W on e85 with aero in TT5 is still really fun at the 140-160whp level if you can get the car light enough. Knowing that a turbo system and cooling upgrades will add significant weight, you can easily aim for a 2250lb comp weight in 5 so you can dial in the car/driver before adding power.

 

Yeah I've been reading about it. I was thinking the same on the BBK. I really just want get out on track again so right now my goal is to get it running without the turbo and aim for track rat status. Brake are going to wait for now.

Damn, talking about crushing a strangers dreams with straight up facts.

I went and looked into TT3 at Sebring where I would be running most often and the TT3 lap record was set by a C5 at 2.17.6xx. My lap record in Champcar trim was a 2:45.x with a 9LR wing, a splitter, a pretty used up set of 200tw tires and cut stock springs suspension. This is only a couple seconds off the TT4 miat times. So that gives me hope that with some bigger aero, stickier tires and updated/refreshed suspension I could be competitive in TT4. The TT3 and TT2 miata's are running about the same around 2:30.xx. Looks like that's some sort of limit for the chassis at sebring. I'm guessing not enough top end speed for the big straights.

Thanks for the heads up.

 

Understood. With no turbo, no need for BBK.
I ran Spec Miata for several years, with Hawk DTC 60 pads, no brake ducting, and the brakes were great. I changed them at the end of each season more because it seemed like the right thing to do, they were still only mildly worn.
And I did race with the turbo, but it is clear the pad and rotor parts will go away at the end of each weekend.

 

So the brakes were fine but just dead pads each weekend? For champcar I would go through a set of gloc r8s each race running nb sport brakes and no ducting. Seems like an ok trade off till I get a bbk.

 

Well, the DTC 60, stock non-sport calipers, with 3 inch ducting, could be used with the turbo through a weekend.
But the heat caused them to curl into a mild banana shape, so that the pedal force required rose a lot during some races.
Livable, but not comfortable.
You can make stock work with turbo short term, but it is not a long term plan.
In contrast, no turbo, Spec Miata, no brake ducts, non-sport calipers, no problem. The grip far exceeds the HP so the DTC 60 brakes wear fine, like your endurance car.

 

Following along this thread closely. I was building my NA8 for TT3 class earlier this year before my ADHD got the best of me and I changed chassis.

Only got one TT3 event in my car and was held up by traffic just about all day except for two laps. At my weight and running 245 RT660s, my car's max HP limit for the class was 294 I think. Given how NASA calculates average HP, I think I could've run up to about 310whp peak. The only event I ran, I was at ~270whp peak. The whole car was pretty underclassed and my driving could've been better, but I was good for 6th of 9 on the day, within half a second of 5th place. Lots of time could've been squeezed out of the setup. Was on 15x9s but should've been on 15x10s. Car could've used more aggressive rear aero. Way more power allowed with street tires or just dropping a bit of power and running Hoosiers would've probably been even faster, as stated by Doward above who's way smarter than I am. I think the car could've pulled podium finishes in TT3 once optimized. This was in the NASA SoCal region. Not sure how the competition here stacks up compared to your region.

Anyways, bit of a tangent there. Stoked to follow along with the project and see how things go for ya!

 

Getting ready to buy a turbo kit and I think the easy button is the full kraken EFR kit with a 6258. I'm probably going to go with the 5.5" intercooler so I don't block too much of the radiator and I'll be below 300HP. I'm still on the fence on top vs bottom mount but leaning for top for ease of access. The low mount is interesting for lowering the weight and smoothing out the exhaust exit from the turbo. It's a track car so not PS or AC in the way.

Any opinions to sway me to larger 7" intercooler? Opinions on top vs bottom mount?



​​​​​​​Thanks, stoked here too. My ADD is all over the place and I thought about moving to an NC myself but I'm heavily invested in the NA/B chassis and have second caged chassis sitting around.

 

I was going to do a turbo BP before switching to a K swap, and had decided on the top mount. IMHO, the low mount creates more problems than it solves unless you're looking for really big HP.

BTW, I have a brand-new, uninstalled Kraken manifold/downpipe in the classifieds...

 

Here is what I know and my setup from one year of running my turbo BP in Gridlife Touring Cup. Power is 200-225whp.

Kraken manifold/dowpipe and EFR6258 are the easy button. I run the side mount turbo for ease of access to CHRA ports. EFR's are also very sensitive to oil pressure and oil drains. I run a Turbo Smart oil pressure reducing valve pre-turbo and a -12 drain line. A low mount setup EFR maybe have issues with the drain plumbing getting enough flow.

I would suggest doing ALL the safety measures you can to support the turbo. Mine has Inconel studs that are Resbond thread locked into the manifold, titanium flange nuts with safety wire, a turbo brace, and a downpipe brace. One year of use (1 test weekend and 4 race weekends) and I didn't have any issues with the turbo coming loose.

I run a Vibrant 12800 core (same as Fab9's Stage 1 350whp offering). I don't log IAT, but I don't feel any depreciable loose in power over a 15min race. I do have ducting on the intercooler that insures all the air coming to the intercooler flows through the intercooler.

For cooling I have a Racing Beat Type 2 bumper, fully ducted all the way to the SuperMiata crossflow radiator. The intercooler is spaced out in front of the radiator ~6". Highest water temps I saw where around 210-215*F when racing in traffic in 90*F ambient temps. For cooler ambient temp races, it was actually over cooling (block off plates are on the plan for the winter).

Oil cooler (13 row Setrab) lives where the passenger side headlight assembly (NA) used to live. It gets fresh air from a TSI that flows into a ducted inlet. I don't recall oil temps (in the bottom of the pan) getting above 260*F.

 

Awesome, thanks for the info. I went ahead and put in my order to kraken and now I wait. I super easy buttoned it and just ordered everything in the EFR builders kit.

What's up with the EFR's being oil pressure sensitive? I hadn't read about that.

What are you running for a fuel pump? I don't actually know what is in the tank on my car as it's been there since I bought in '17, maybe I'll pull it and check before ordering anything. I was thinking of going up to a DW200 or the like, I'm already running an AEM fuel pressure regulator so I'm not worried about overrunning the factory FPR.

 

Their turbo seals leak if you exceed their maximum recommended oil pressure of 45(?)psi. That’s pretty easy on any modern engine, which is annoying. I see ~120psi on cold starts, cruised at 77-78psi for 9 hours on the way home from Sonoma 😳

but there are solutions, turbosmart’s v2 regulator restricts oil pressure down to 40-45psi.

BW also wants you to never reduce drain size below its .42” (basically .5”) drain diameter, a lot of adapters and hose ends are smaller, so plan on -10 minimum and keep that in mind for any adapters.

 

Damn, good to know. Thanks for the info.

 

The EFR manual has great information on pressures and plumbing sizes.

I'll echo what Curly said. I use the TurboSmart OPR v2 as well because its returnless, so one less potential leak point and reduced plumbing. I was getting oil in my charge piping and some through the exhaust during preseason dyno tuning. Since adding the OPR, I haven't had oil in the charge piping. I still get some smoke through the exhaust, but my oil consumption is very low.

Early on a lot people went with -10 hoses for drains which meet the ID requirement, but -10 fittings and hose ends often drop below the required ID. Most drain adapters use a 3/8NPT port, but all the 3/8NPT to 1/2 hose barb adapters are going to have a smaller than required ID. AGP is the only place I found that sells a flange with a 1/2NPT port (Oil Drain Flange for EFR GT25 GT28 GT30 and GT35 w/ O-Ring Seal - AGP Turbo) so I could maintain the minimum ID all the way to the pan.

 

Thank you both for all the great info. My first turbo part showed up today. Woot!

 

Hey, some how missed your reply. Thanks for the info. I ordered a full kit already but appreciate the offer.

 

Boost parts are here!! I have no idea how he can get them shipped internationally so fast but the spent 4 days "in flight".

 

Exciting stuff! Keep us posted