Hello from 1700 lb. Custom Tube Chassis Miata Build Owner (DIY Exocet Knock-Off))
 

Hello! I'm Warren from Fort Wayne, Indiana.

I currently have 3 Miatas:
• 1999 #W8LOSS Tube Chassis Miata, 186k miles (Owned since October 2016)
• 2001 Street/Daily Miata, 96k miles (Owned since November 2017)
• 1999 Parts Miata, 192k miles (Owned since Septermber 2018)

After doing some reading on the forum, I finally created an account.
I thought about posting some questions, but after reading the noob tutorials, I think I'll hold off until I've read some more.
I didn't have the best experience searching but I'll try that some more too.

The main reason I'm here is to improve my tube chassis build for autocross while learning to tune/turbocharge and minimizing/eliminating external costs.
I've gotten deep into autoX over the last 2 years and now I never miss a local event.
I want this car to be super competitive. It has done well on stock power (116bhp) and 225 BFG Rival 1.5s, but I want more ;)

I'll admit, I don't know exactly how much more, but I think I want 200-250 bhp (and 275 or 295 x 15" Hoosier A7 tires).

I'm not sure how much power I want since I haven't experienced a Miata above stock power.
For the autocrossing I do, I think having as much torque available across 2nd gear is very important.
I have considered supercharging it, but it seems more expensive, there is less information/support on it, and it isn't as easy to make big top-end power with a good mid-range torque level.

So that brings me here!
I asked the Exocet owner's FB group about the best FI option for autocross and most people said to do a MS3 PNP with a GT2560R.

So far I have the car running on the MegaSquirt with an AEM wideband hooked up.
I have 640cc Flow Force injectors ready to be installed when I think I'm ready to tune for them.

I'm having trouble finding the confidence to know what changes to make in Tuner Studio (I bought the ultra edition of it and MegaLogViewer BTW).
I'll do more reading and searching before I start a new thread or ask any questions haha, but I just wanted to throw that out there.
For now, I'm still using the same tune that came with the ECU when I bough it.

A noob sticky told me to keep these things in mind:
• Power goal
• Budget
• Abilities
• Timeline

To which I'll answer:
• 200-250bhp
• $5,000
• I'm 98% sure my dad and I can do all of the work
• I want the car to be ready for the first 2019 autocross event
(probably late April, but sooner would be nice so we can disassemble and paint the chassis before the season starts)

That's probably enough babbling for now.
Some pictures of my cars are below.
The best way to keep up with me is my Instagram https://www.instagram.com/zeek55555/
my website https://www.warrendbarnes.com/
or my wheelwell https://wheelwell.com/warren-barnes/...zda-mx-5-miata

Thanks in advance for all the help!

https://cimg9.ibsrv.net/gimg/www.mia...3d3c526631.jpg
#W8LOSS Miata

https://cimg8.ibsrv.net/gimg/www.mia...f963fd944d.jpg
My trip to the Tail of the Dragon in July of 2018
https://cimg2.ibsrv.net/gimg/www.mia...4ddafbe883.jpg
The 99 parts car

Welcome,

That is a very cool home built tube miata!. did you weld it up yourself?

for autox, you want a fast spooling setup that will have good low/mid range grunt with a decent top end.

since you have a 5k budget, that is no problemo to achieve.

The best setup on the market is a trackspeed EFR 6258 turbo kit, its capable of producing between 220hp - 400hp, depending on the boost level. costs $3099
If staying with a stock motor and 5 speed gear box, stick to about 250hp max.
Then add clutch, FM level 1 is great $400.
3" exhaust ~$600
Intercooler and piping $300-400
BOV ~$200

or you can go with a Kraken T25 manifold/downpipe kit (~$800), and a gt2560r ~$900, plus all the above addons.

A 2560r spools just as fast as a EFR 6258, but doesnt have the same power potential. it can make between 160-280hp or so.

Thanks for the compliment!

My dad and I have done all of the work to the car, including the welding.
While he does fabrication as part of his trade, I used this project as an opportunity to learn.

I'm okay with getting away from kit options. I don't mind ordering individual parts if it means I end up with a better end result.

I haven't heard of the trackspeed EFR 6258 turbo kit, but I'll look into it.

I'm interested in manifold options at the moment. I wonder what the best options for early RPM boost are.
Originally I was thinking about going with the Flyin Miata log manifold, but I've heard there are better options.

I was told that I might as well go with the GT2560R because it spools within a 100-300 RPM difference and doesn't cough out at the top end of the rev range like the smaller turbo does on a 1.8.

I'm okay with more power potential, but want to be able to dial it back if I think that's appropriate for that day's racing application.

I understand there are a few drivetrain parts that don't like power numbers over 250 (rods, pistons, crankshaft, transmission).
If I could be capable of 300 but have it dialed back to 230 until I make the appropriate upgrades to handle the power, I'd be okay with that. Because right now I don't know what power level I want to end up at.

Best DIY route is to get a kraken t25 manifold and downpipe set, and source your own gt2560r.
Kraken has the best cast t25 manifold/Downpipe combo on the market right now. Its built like a tank and flows really well.
Much better than FM or begi cast manifolds. And cheaper too.

gt2560r will suit you nicely. And can potentially make more power than your engine rods or 5 speed can handle.

only things you need to upgrade for above 250hp are the engine rods and get a 6 speed.

crank and stock pistons are fine at 300hp. Crank is good for 500+hp.

Not really. On paper, it might get close. In the real world, there is not even a comparison to be made.

If you are using a GT2560R in the Year Of Our Lord 2018, it's because you cannot fit an EFR6258 into your budget. Period. The EFR outperforms the 2560R in every metric.

You can check out MK Turbo as well. That's what I ran on my car. It's budget friendly and comes with a full exhaust.

Also, what Savington said - there is no turbo that spools like the EFR. It's totally instant.

If you are budget conscious, I would look hard at the MKTurbo setup. IMO, if you aren't using my setup with an EFR, that's the direction you should go.

After some reading and watching videos by Greg Peters at TheCarPassionChannel, I think the Trackspeed EFR Turbocharger System probably is the way to go.
I'm glad I haven't bought anything besides an ECU, wideband and injectors yet.

get the best right away and dont look back.

an efr 6258 can be run with the low boost canister with like 5-7 psi of boost, so you can keep it as low as 200ish hp if need be. or crank it up to 400+hp if you eventually want a mental kart.
Its really is a do-it-all turbo.

I might be biased, but I think that's a great idea :)

​​​​​​Perfect. But before I light up the credit card, I should probably feel comfortable knowing what I'm doing in Tuner Studio.

I haven't made any tune changes yet, so any guidance on how to learn tuning would be appreciated (I just know some tuning theory).
How-to-tune is still on my list of things to search for in the forum.