Buzz

I need help completing my winter build. I have a 1994 Miata that started its racing carrier as a "spec Miata". Since I no longer have time to race and only do track days I decided to build the car so I can hang with the Corvettes and other cars at these events. My goals are to have a 400 whp Miata that is reliable and as low maintenance as possible. Unfortunately in Ohio there are not many turbo Miata track people.

Here is what I have so far
-full cage
-shock tower brace
-1 set JIC FLT-A2 shocks/springs custom tuned for this car
- built 1.9L (overbored) turbo engine that I plan on running E85 with (I can provide details... no expense spared other than STOCK CAMS)
- Garrett GTX3071R dual ball bearing turbo
-Larger Koyo radiator, Larger Intercooler
-AEM computer
- LS1 coils
- Accusump system
- Begi Exhaust manifold
-coolant re-route
- Spec Miata sway bars
- Mazda Speed Miata brakes with Hawk pads
- front and rear aero (splitter and wing)
- 15 x 9 6UL wheels
- 5 speed Quaife trans.

Questions I have.
-Do I need to get upgraded oil pump as I was told the stock one will fail? I was told to get this form Boundary Engineering .
-Is my Turbo to large and if so what size would be recommended for my goals?
-Can I run a Hoosier 275 R6 on the 9 inch rims. They mounted up and look good but I was told by someone on the forum I need you 10 inch wheels?
-Do I need an oil pan baffle and if so which one do is recommended?
-Is the spec Miata sway bar set going to work or is there better?
-I do not have bushings anywhere on the car so which ones are recommended?
-I still have a stock intake manifold and throttle body. What do you recommend for the upgrade on this if it is necessary?
-Can I just upgrade the front rotors and brakes or do I need to do all four wheels?
-Do I need OS Giken Limited Slip?
-Is there anything else I am missing?
As I said prior reliability would take priority over outright speed so what would be your recommendations? Thanks

hustler

iTrader: (6)

Questions I have.
-Do I need to get upgraded oil pump as I was told the stock one will fail? I was told to get this form Boundary Engineering .
Yes, you want Boundary oil pump gears.
-Is my Turbo to large and if so what size would be recommended for my goals?
No, it's "just right", maybe a 2871.
-Can I run a Hoosier 275 R6 on the 9 inch rims. They mounted up and look good but I was told by someone on the forum I need you 10 inch wheels?
Maybe
-Do I need an oil pan baffle and if so which one do is recommended?
Not a bad idea, it will be a custom job.
-Is the spec Miata sway bar set going to work or is there better?
Follow the 949 formula.
-I do not have bushings anywhere on the car so which ones are recommended?
949 is the way, drink the Kool-AIDS, take away the pain.
-I still have a stock intake manifold and throttle body. What do you recommend for the upgrade on this if it is necessary?
Yes, call ARTech.
-Can I just upgrade the front rotors and brakes or do I need to do all four wheels?
All 4 is absolutely required, TSE's "biggest brake kit" and M-Tuned rear kit is the way to glory.
-Do I need OS Giken Limited Slip?
We all need one.
-Is there anything else I am missing?

As I said prior reliability would take priority over outright speed so what would be your recommendations?
Your shock tower brace does nothing, your shocks are huge pieces of ----, and MSM brakes are a special kind of crap usually reserved for Eastern European cars...there are also some negatives that I won't go into right now. Seriously, if you have all this bauce stuff, get some baller Xida 4-ways instead of that JIC crap. Retards on Club Roadster will pay more than they're worth for JIC crap.

mx594m

iTrader: (1)

heavy duty valve springs, and rev the crap out of her

hustler

iTrader: (6)

I recently did SS valves in my car at 250whp because after 100 hours I saw very slight erosion on one exhaust valve (probably a bad valve since it was only one) so at your level SS intake and Inconel exhaust valves are probably not a bad idea.

bbundy

+1

bellwilliam

iTrader: (1)

since you are on the upper end of the whp. I would recommend everything on Emilio's list:

https://www.miataturbo.net/showpost....&postcount=123

Stuff Miata track turbo guys do wrong

No hood vents
Hood vents in the wrong location, i.e behind #3 cylinder
No full coverage undertray
Radiator core not 100% sealed for air leakage around it
No reroute
#6 or #5 plugs
Stock coils
NA batch fire ignition
NA6 batch fuel
Pump gas of 92 or lower octane
Non-Inconel manifold studs
OTS BEGI or FM manifold w/o turbo support brace
OEM Garrett internal wastegate and >10psi instead of VTA
Too small VTA BOV
Intake pipes without beads
Intake pipes held on with ordinary worm drive hose clamps
Throttle plate not epoxied
Solid motor mounts broke other stuff on car
OEM diff mounts - broken exhaust
No V-Band in DP
OEM Rods
OEM pistons
OEM oil pump
No clutch bypass for starting leading to toasted thrust bearings
No oil cooler
No trans cooler
No diff cooler
5 speed transmission (went through at least four I bet)
Rubber lines for turbo oil and/or coolant
Restrictive tube/Fin I/C from big name American company instead of superior Chinese Bar/Plate off ebay (who knew)
Piggy back ECU
>13psi with NA cam/crank angle sensor + ragged edge tune = det
No WB02
WB02 in wrong place
No EGT
Coolant temp sensor at front of head
Heater bypass w/o restrictor
OEM 16psi rad cap instead of 19psi Koyo/Stant
Too few/misaligned exhaust hangers = cracked DP
Bad welds, cracked DP or exhaust
5th injector in manifold
RX7 460cc injectors
RC engineering injectors
No det cans used during dyno tuning
Boost turned up after dyno, then raced
Boost turned up way past highest efficiency island on compressor map
Zero safeties built in to ECU (overboost,EGT,WB02,coolant pressure etc)
Insufficient heat shielding for heater hoses, master cylinder, trans tunnel
More than one change in intake pipe cross section dimension between compressor-I/C or I/C- TB.
Under drive pulleys
Road tune only for WOT/peak boost only (no steady state part throttle dyno tune)
$25 junkyard turbos
Non-water cooled turbo

Non-engine stuff done wrong

Koni yellows with GC coilovers
Spec Miata suspension
OEM rubber suspension bushings
NA6 diff
Open diff
more rear camber than front
Anything less than 9" wheels
205/50/15's
Zero front aero but tons of drag/lift inducing cooling holes in vain attempt to stop overheating
No wing
No hard top
Bolt in cage
NA8 brakes with Hawk Blues
OEM bone stock hubs
OEM end links
A/C components still in car
>2400lb comp weight

Boost Joose

ARP wheel studs, some sort of doubble or tripple pass raidiator., equal legenth tubular manifold.

Pics? engine specs?

ZX-Tex

iTrader: (15)

-Do I need to get upgraded oil pump as I was told the stock one will fail? I was told to get this form Boundary Engineering .
Yes, good idea. That or an ATI harmonic damper. The pump gears are cheaper.
-Is my Turbo to large and if so what size would be recommended for my goals?
I would get a 2871 but what you have will work. It depends on your driving style and your tracks. Try it out, make sure you use a MBC or the like to help spool.
-Can I run a Hoosier 275 R6 on the 9 inch rims. They mounted up and look good but I was told by someone on the forum I need you 10 inch wheels?
You can run the 275 A6 Hoosiers on a 9" wheel. You do not NEED 10" wheels. You are giving up some grip but it will work. You will want/need fender flares.
-Do I need an oil pan baffle and if so which one do is recommended?
That or an Accusump
-Is the spec Miata sway bar set going to work or is there better?
+1 on 949
-I do not have bushings anywhere on the car so which ones are recommended?
Energy Suspension is what I am using
-I still have a stock intake manifold and throttle body. What do you recommend for the upgrade on this if it is necessary?
There is a thread on miata.net about the throttle body shaft breaking. Reinforcing it with epoxy seems to work. Go search for that thread there. It is a good read.
-Can I just upgrade the front rotors and brakes or do I need to do all four wheels?
TSE 11.75" Wilwood kit on the front, sports on the rear, proportioning valve to dial in the balance. Also duct the front brakes.
-Do I need OS Giken Limited Slip?
No, it is a nice to have. Plenty of us running respectable lap times with a stock Torsen. Take that money and buy seat time with it.
-Is there anything else I am missing?
See the list posted above

As I said prior reliability would take priority over outright speed...
Good call. See the list above. 400 HP, especially if it is 400 rwhp, is a lot of power from a 1.9L track engine and will stress everything. I would turn it down myself. Driver>tires>suspension&brakes>power

hustler

iTrader: (6)

I will now argue with you, in another color:

Stock coils
They suck but they work
NA batch fire ignition
They suck but they work
NA6 batch fuel
They suck but they work
Intake pipes held on with ordinary worm drive hose clamps
I have no problems with a worm-gear compressor inlet clams
OEM oil pump
~250whp should be fine with this
No oil cooler
Show me a working set-up
No trans cooler
Show me a working set-up
No diff cooler
Show me a working set-up
No EGT
I don't see how this is essential. I also see it as adding a potential failure point on a manifold.
OEM 16psi rad cap instead of 19psi Koyo/Stant
My 16psi cap is just fine
RX7 550cc injectors
They suck but they work
Zero safeties built in to ECU (overboost,EGT,WB02,coolant pressure etc)
Show me a working example on an affordable computer.
OEM bone stock hubs
I run shitty China-bearings and they've lasted longer than OEM 10x over,with only adding good grease.
>2400lb comp weight
Racecars only. I'm at 2440lb and the car is barely livable for a Friday trip to the office.

hustler

iTrader: (6)

Jeg's Camaro studs are cheaper and just as good, I agree on the radiator, I have an unequal length manifold and my car has not burst into flames yet...it also makes pretty good numbers and I'm "below prime" on my typical MAP target.

jbrown7815

iTrader: (1)

Thanks for posting this.

jbrown7815

iTrader: (1)

Ah nvm

emilio700

iTrader: (3)

=$20k on drive train

A 400whp Miata is roughly equivalent to a 600whp Vette. Know that it is cubic $$ and as far as I know, only one person in the world has successfully built a regularly raced (not just HPDE) 400whp Miata. He's using a Rotrex, spent a few dollars and is basically a rocket scientist.

If you're getting the feeling that we're all gently trying to talk you out of it, you're right. We'd much rather hear of your reliable and super fast 300whp build beating up on Porsches rather than long threads about never making it last an entire day at the track at 400whp. Many solid 300whp builds around the world. Big jump from 300 to 400 in a Miata.

hustler

iTrader: (6)

+1
I have an insanely baller, 1% Miata...but frankly I can barely afford to "race" the car at 250whp and keep up on my gun hobby, food hobby, and still hit the Roth IRA every month. I'm spending about $150 each race weekend just on fuel at the track. If I had to pay for broken parts, I would not be very happy and you're going to break stuff along the road until you find the formula. I'm not saying you're not rich, I'm saying "you may not want to sink that kind of scratch into a ------ ride" when you could go for a ski-weekend and contract venereal diseases.

Something else to consider is that after you pass the 10lb/hp number, the car becomes less white-knuckle thrill and more of a "how straight can I exit the corner to put the power down" affair. The need for momentum enriches the experience and is a balance with 5th gear throttle steer...I have both.

Boost Joose

Something I'm not sure of that big numbers like this could run into are problems with the stock crankshaft.....what kind of power can the stock one take?

TurboTim

iTrader: (9)

all of it.

Savington

iTrader: (31)

+2. You can build a stout, reliable 300whp package for $10-12k. 400whp is $20k.

Buzz

Thanks for all of the advice you guys are great!

It appears that the consensus seems to be that there is no such thing as a reliable 400 whp Miata "or that it is a rare thing. The whole reason I switched from racing high horespower cars (I ran a C5 corvette with 550 whp for two years) to spec Miata is because I hate working on cars while at the track and I do not have a crew.

My set up last year was a spec miata with a Mazda Speed Miata turbo (modified by Blouche) on E85. That set up put down 255 whp. That set up would let me hang with all but the fastest Vettes and Porsches (top 10%). It was a blast but I broke a rod at Mid Ohio last year and decided if I was going to build a forged engine why not go for more power.

Keeping in mind that reliability and low maintenance first (I am OK spending money on good tires) should I shoot for the 300-350 range? Is anyone else out there running a set up like mine at this power level happily? Can I do this with my current turbo 3071 and simply turn down the boost or do I need a smaller turbo or for that matter should I put on my IHI turbo that got me 255 whp with a 94 head on stock engine. New engine has 99 head that is ported. Would that other turbo get me to 300?

Sorry for all the questions and thanks in advance for the help.

Boost Joose

What are the major differences in a 300 whp and 400 whp track miata?

What is all of it? What is the limit of the stock crank? Has anyone ever broken one?

Savington

iTrader: (31)

The ideal 300whp turbo is a GT2860RS. The 2871R will do a similar job down low but give you about 75whp worth of headroom if you decide someday that you miss working on the car all the time.