Father Son NB project
 

Hi folks!
I have been lurking for several months trying to gather information for my son's NB build.
Love this site!

I am semi retired, somewhat health disabled father. My son and I intend to build his NB into a fun fast street car, that he can auto cross and maybe even start playing with track days.
Our goals are razor sharp handling and a scary fast car that tops out in the 400hp range. The car will be more Sunday driver/race car than a street car.
This is NOT a serious track weapon...Though the only issue should be too much power.

As far as my experience I have built and run a low 10 second 1300hp Cummins powered truck, a very serious 70 Chevelle, and many other high performance cars, trucks, and offshore boats.
I quickly discovered that all my experience counts of nothing on this NB. I have zero experience with a Miata.
Getting a car to go around corners with this intensity is also a new deal to me.

Full disclosure: Until this year I thought the Miata was for girls, hairdressers, and men that prefer penis....Who knew? :)

The 2000NB project in semi sorta order:
Car is stone stock
1) Stage 2 Fm clutch/flywheel/seals (on its way). Depower rack.
2) Hard dog tall NA bar, Kirkey seat bolted to the floor (my boy is 6-5"), harness, steering wheel, raise the column (if possible).
3) Suspension...Xidas...probably with the happy meal deal.
4) Megasquirt
5) Ignition, Fuel system, injectors
6) Forged internals and refresh, 6 speed, OS Giken, re gear.
7) Turbo EFR. I Like the Fab 9 setup, but I believe no Vband .63 A/R at this time?

The starting budget is $15,000.00...lol!
We all know how that goes!

Always interested in and appreciate advice!
Thanks in advance!


Cheers,
Jamie

Trackspeed also has a EFR setup, check it out!

Thanks!
I talked to Andrew the other day about another product he is working on.
It was just after our conversation that I discovered that the EFR Vband did not come in the A/R we are looking for.
It is very likely that we go with the TrackSpeed setup.

From EVERYTHING I have learned from this forum, go with Andrew and don't look back. There is a reason he is a constant part of this forum and Fab9 is not.

You should ensure he can fit in the car properly and safely before spending all that money on go-fast stuff.

Welcome to the madness!

This sounds like a great project with your son. My only suggest is that you might want to re-think your power goals - 400hp in a Miata is STUPID-FAST. Think power/weight rather than outright power. But, if you're dead-set on "big power" then go for it! A full-on K-swap, or LS swap would get you there but be sure to factor in a whole new driveline to handle that kind of power reliably.

Enjoy!

^This is the most important post in this thread.
Now onto the power goal. Where did 400hp come from? 400 HP in let's say, a vette.. is not the same as 400 HP in a Miata.
​​​​​​​Take into consideration the final weight of the car and what your goal is that you're trying to meet. At that power level you will be pretty much redoing the entire driveline to accommodate for dependability. Otherwise you will go through transmissions and differentials more times than you want to replace.

Good point! We took the seat out of the car and I made some careful measurements day one.
With a Kirkey seat bolted to the floor he fits to include the broomstick rule...Just! If you whatever reason things stack up and he ends up a bit too high I will drop the floor.
Definitely not a comfortable daily driver for him, but this car is not intended to be a daily.

Currently the car sits at 2200ish pounds.
400hp came from acceleration figures he wanted to reach and my thoughts on the nature of the EFR 6758. Trying to match his dreams with reality, but also realize if the power is there he is going to use it.
Obviously the car will be driven around at 300ish and perhaps lower at the track. 400 is a big sketchy number in the Miata. Of that I am aware.
Indeed we intend to replace pretty much everything.
From what I understand the 6 speed will live quite a while at that horsepower level and it is at the track where the issues arise? Am I out to lunch there?
Obviously anything can be broken and given my Son's terrible genetics I am sure he will do just that. :)

Thanks for your thoughts folks!

What an awesome dad-son project. I'd totally do this for my boys but they're 1 and 4 and require back seats to sit in.


I'd factor in a second 6 speed as a spare so you can drive it while you figure out a way to get 400 bhp from the crank to the driveshaft reliably.

for example:
https://www.miataturbo.net/miata-par...e-miata-71777/

It seems like ~350hp is kind of the reasonable threshold with a miata drivetrain. Beyond that, even with a bulletproof built motor, you start to have issues with the 6 speed, rearend, and axles. If you've got power goals in the 400+ range I'd be looking at V8 swaps.

For the HP goal and starting project amount. I would look into doing a v8 swap. Keep it simple

This.

At the cost you're looking at to get to the level of 400hp and all the things that will break along the way, the V8 swap is probably the way to go. At 300-350 the miata still makes sense.

I'll ask what Thirdgen always asks people: have you been in a 400hp miata before you came to decide an HP number?

Sounds like a fun project (I hope to do something similar with my boy one day).

Andrew is definitely your guy for the project if you're dead set on a 400 hp BP.

Indeed having a a spare 6 speed it pretty much essential!
I picked up a cheap high mile 6 speed last week (going to be our back up box). I am going to tear it down and have a look at the pieces and tolerances....hopefully it is in decent shape!

I looked into the RX7 gear box, but the gear rations seem a bit odd, though I have not carefully dissected the numbers yet...Some more so than others! Am I missing something there?


350hp does seem more reasonable and for daily driving 300 more sensible yet.
The problem is once the car has a turbo and engine that can make more power you are likely to use it...If even only on occasion. You need to keep in mind that it isn't necessarily me driving the HP goals! :)
My first instinct was to stick a V8 in it. After driving both a LS and turbo Miatas back to back my opinion changed. To be fair the 300hp turbo had the basic strip out and the LS powered V8 was more stock in appearance, but the two cars felt like apples and bananas. The v8 being the banana. Could it be suspension setup? Sure! To me the v8 took the Miata out of the car.
Either way my son was set on the 4 cylinder....So here we are.
Also 400hp is the maximum goal, not necessarily the every day setting.



I have driven a 350hp Miata. Fairly sporty in the first 3 gears! The concentration is real ...The car is no joke at those power levels that is for sure!
400hp is the most that can be made on pump gas (no E85 here) with the setup we are looking at so that is the ultimate goal.
There is nothing saying that it will get driven at 400hp all of the time. Most guys with fast Miatas tend to turn the power down for more sensible driving and then crank it up to embarrasses some expensive sport car on the street or to hoon around a bit.
I suspect our car will be no different.
The car is all about fun and wont be extremely serious about anything.


I hope you do as well. Nothing better than staying connected with you kids and family.
Everybody says great things about Andrew and his products!
Having no experience with the EFR my only reservation is the internal waste gate and its ability to tame boost creep.
I need to do a little more research on that


Thanks all for taking the time to post your thoughts!

Cheers,
Jamie

I hear that!
We talked today about budget....Pretty daunting project for his first...Work wise and money wise!
So far he has refused to blink...though today's conversation made him swallow hard a few times :)

I have put so much research and thought into a built plan for the 4 cylinder I am ready to go!
If you know what I mean?
I may help him a bit....I am getting addicted to the little car!

We are off to our first autocross this weekend!
That will either cement the deal or sink it....Considering how capable a stock Miata is I assume he will come home hooked!

Cheers,
Jamie

Everything in the cooling system and drivetrain will require major modifications to hold 350 horsepower on the track for 15 or 20 minutes. You won't be able to easily keep it cool unless it is cold outside. You will also need much larger aftermarket brakes and ducting.

FWIW, 250whp catches and passes C5Z06's at the track in these cars, back when I was at that power level.

Our plans for cooling are:
A reroute, Trackspeed's big mammajamma radiator ( a little oversized but I hate buying things twice), an oil cooler (yet to research, but know we need one), 600hp Precision intercooler, and a big three way vent system in the hood (in the right place)...I forget who makes the one we want.

Have been speaking with my son about the drivetrain aspect and I think we will stick with 350hp and a 6 speed for now until a better option comes along (T5 please! :) )
Likely starting at 250hp and working up from there at the track.
Brakes will eventually be bigger, but I am not exactly sure how big we need at this point. We installed the 949 stage one kit...just to clean up the brakes....I am blown away by how good this little kit is!
An 11.75 front kit and proportioning valve will likely come into play, but my son's driving has to come a long way to catch up to what we have already.
Ducting we need...No idea where to start yet.

The rear end and shafts still need some thought. I know S2000 guys make it work up to 600hp, but I have no idea how they do that other than an OSGiken (sp?) and good bearing caps?
I keep hearing some odd named fellow that the S2000 guys use.

Thanks for taking the time to reply!
Please hit me with any other thoughts you might have!

Cheers,
Jamie

Trackspeed sells DIY-mounted Setrab-based kits at a great price for what you get. Get a 25-row :)
Trackspeed Oil Cooler Kit

Singular vents. Lots of MT.net vendors carry them, too.

Singular Motorsports Hood Louvers: NB Miata Singular Motorsports

Thanks AFM!
Those Singular louvers are the ones I was looking at!
I will look over the vendors and buy from someone here.

Figures Andrew has a track/turbo sized oil cooler. :)
I need to spend some time figuring out radiator/air flow/ducting/redirecting now....The rabbit hole is deep!

The steering rack de-power happened over the weekend....Feels so much better! #1 son is thrilled and I am happy to get this thing moving!
Did a simple stringline toe in check and It looks like the car may have been hit...One of the front tires sticks out farther than the other....Crap!
Hoping this is in the sheet metal, but the car is headed to a good alignment rack for a serious look over. Double crap!

With any luck the clutch/flywheel will show up for next weekend!


Thanks for your reply AFM!

Cheers,
Jamie

for 400 reliable whp and mechanical kindness, a c30-94 rotrex is a much better choice. You will have less drivetrain issues due to the lack of low and mid range torque spike, like a turbo, and you wont have any underhood temp issues. Rotrex isn't a popular choice, especially in a website called miata turbo, but some of the long standing fastest miata lap records are done in a 400whp rotrex. Just a contradictory statement for you to consider.

For rear end settings, contact Ben at Puddy Mod Racing. 352-650-3763 He is THE expert on miata and s2000 differential setups. Not only will he send you the complete parts package you require, but he will tell you AT LENGTH how to set it up.

Also, dont be afraid to pump out the power, there are miatas in the 500+whp range (turbo, and several v8 miatas) and they hook with minor grip modifications.

You may be aware now, but your 15k budget is quite low. 25k is a more reasonable minimum budget for a complete 400whp miata, if you don't have your own shop or fabrication skills. 50k covers a complete build with high end parts, but it also would pay for a complete turnkey LS3 miata from Flyin Miata or V8roadsters.

Interesting thoughts on supercharged torque output. I could see the soft midrange saving parts alright.
The downside to supercharged cars (I have owned a few) is they are hard on the bottom end and have been anything but reliable. Perhaps the Miata (Rotrex) systems are different, but the Miata bottom end seems far from stout...and since that is what drives these things.....I would be apprehensive about 400hp with a blower. That is just my first blush at the thing, and I have zero experience with a supercharged Miata of course.

As far as out budget goes I am aware it is a bit low....I was aware of that day one, but that is the number my son started with. He either has to make compromises or adjust his budget. There is no way we are going to spend 50K though.
I have basic fabrication skills and most of our fabrication plans are pretty light duty. I have friends with serious fabrication skills if we need that, but I am trying to keep fabrication costs down

Puddy Mod! That is the name I was looking for! :)

I have never heard Miata, 500hp, and hook, in one sentence before?
How is that accomplished?

Thanks for posting!

Cheers,
Jamie

Are you speaking of the parasitic drag of superchargers? The rotrex has a much higher efficiency than other types of superchargers, but I suppose it does put some amount of strain on the crankshaft. I have read that it actually can help engine harmonics, as it sort of acts as a damper.

I dont have first hand experience with a 500whp miata, but it seems the people that have traction issues (most high hp miatas) aren't using extremely sticky tires. They usually are using 200 or higher treadwear tires. I personally find this ridiculous, and the main reason for the general consensus of "miatas have poor traction" If the tires are lasting more than 8-10 thousand miles of regular street driving, those aren't the correct tires.

However, the miatas that seem to have no traction issues are using M/T drag, and Rival S, Toyo RR, or hoosiers for the circuit.

I'd not try to get 400whp out of a BP engine in a track environment. It would not be reliable. LSX at that level.

^really? I would think the drivetrain would be an issue, not engine. The off the shelf built engine TSE has for 4500 is rated for 500whp continuous.

Indeed we have no intention of going near that power level on the track.

Keep in mind these opinions could be totally off on a Miata and that I have Zero forced induction Miata experience...So with that in mind:

When you have a stock 130hp engine and you turn it into a supercharged 400hp engine there is a great deal of power transferred between the crank pulley and the supercharger.
A conventional roots blower that number is around 20%. In a paxton/Rotrex/Procharger that number is less, but it is still significant somewhere in the 50-80hp range.
A 400hp engine makes 100hp per cylinder, then the front front 2 caps, and that section of crank have entire load of the supercharger to that area. Also the crank is turning one way and the supercharger is trying to turn the other way. Keep on mind how anemicly small the crank studs are and how few of there there are....Check out the cast caps while you are at it.
Though the Miata crank is forged, but it is not a great crank and turns to rubber at very high RPMs...Similar to the stresses of high RPMs the supercharger stresses the crankshaft with a counter force...
If you have ever watched a blower belt whip around it is pretty simple to see that the counter loading is far from consistent and even.
Whoever said the blower acts as a harmonic damper is an idiot....Plain and simple.

I have campaigned supercharged engines where after a couple of dozen passes on the dyno the bearings were anything but fresh.
Then I added 500hp to the exact same long block and went turbo....On the dyno and 30 or 40 passes later I pulled the bearing caps...They looked like new bearings with oil on them!
These are pro built and pro tuned motors. The best crank and bottom end that money can buy...the works.
Ask any engine builder and he will tell you the same thing.
I can't tell you exactly what happens inside an engine, but it is much more violent in there with even the best superchargers.
Maybe Miata has some Voodoo magic in there somewhere?

The 350hp car I drove had Rivals and it had serious traction problems with 225 Rivals?

I'm curious if rotrex superchargers have a similar effect on the bearings. I dont remember the numbers but the rotrex is much more efficient than any other supercharger, and has an exponential boost curve while stagnant parasitic loss.

That's kind of an interesting trade off, bearings or rods.... supercharger or turbo... power loss through parasitic drag or heat...

Were the tires rival? Or rival S? big difference. Age? The 2016 and newer rival s is an improved compound. Suspension setup is important too.

PD and centrifugal pumps are going to be VERY different in this respect.

Any centrifugal style blower will create less bearing wear than a roots style at the same horsepower.
My last supercharged setup had an $8000.00 Procharger and after 30ish dyno pulls the bearings no longer looked new....big power, but 400hp in a Miata motor is also pretty serious power.
Same engine, twin turbos, more power, and almost 40 pulls and the bearings looked as new.
Not a huge deal, but it you are planning on a 400hp supercharged track build you better have a plan for regular engine tear downs....Or at least inspections.

All I know was fresh looking Rivals, but if it was the the less sticky Rivals 3rd gear will still be loose with the stickiest tires made. 2nd will be all over the road no matter what tires.
As far as traction goes? Maybe you are talking a smaller turbo or supercharger setup? The torque of the EFR in a well designed system is much (MUCH) more significant. Unrestrained by thoughtful boost/map control the EFR setups would be all but undrivable in the first few gears.....Even with drag radials....and this car will never see those.
Also remember there are guys that are making big power and then there are saying that are making big power...The car is really designed around traction.

Also the car will have 700 or maybe even 800# springs.

Cheers,
Jamie