I echo the opinion of avoiding forced induction in an endurance car. Our team runs a NA with a BP4W swap that makes 135-140whp on the dyno Champ Car SE provides (Dynocom 2WD 5000 Series). It is a freshly rebuild motor. We can make a little over two hours on a tank of fuel in a dry race with a stock tank, vent moved to the top of tank, and a surge tank. Our typical fill after a 2 hour stint is 11-14 gallons depending on the track, cautions, and driver. So another 20whp we wouldn't be able to make the two hours mandated driver time. Forced induction requires richer AFR's to keep help reduce the stress on the motor, so even less likely to make the two hour stint.

If you're stuck on making 160whp, get a VVT motor and spend your money on rebuilding it make sure its in top shape. You can try to run the NB2 manifold and see if that gets you there, or you'll need a header. The issue you'll run into is that a OE VVT motor has to run the worse intake manifold (VTCS). You MIGHT be able to argue that you got a JDM/EUDM motor and it comes with the flat top so its legal. Don't think for a second you'll sneak it by the other competitors in impound though without clarification from Champ Car. Get a good tune and you should be close.

 

Would high-compression pistons be considered illegal? Shim under bucket lifters? Bigger cams? Lightweight flywheel?

 

In Champ Car? Not illegal, but they would add points. Its possible to build a 500pt car that makes 160-170whp. Glazed and Confused (car built by East Street Miata, who also builds Spec Miatas) is one team I know of that did it. 90-93 chassis, VVT swap, cams, and header. In a dry race they couldn't make 2 hours on fuel. At Barber last year, their fuel tank was stock, maybe with a relocated vent.

 

Agree with Andrew on the fuel consumption. Our analysis of budget racing distills down to gaining as much track position as possible with a car that can comfortably run 2hrs on a tank. The informal BOP adjustments in virtually all budget enduro (including WRL) mean having a fast car is more an exercise in pro level sand bagging than actually trying to go fast. Sand bagging in budget enduro is an art form that the best teams have mastered. This hypothetical 2hr per tank car needs to be as reliable as a hammer too. So a PD blower running a powercard with no intercooling at 10.5:1 AFR on pump gas is a non starter. An unmodified NA6 tank would not make an hour, let alone two.

Andrew and I have won T25 a few times, WERC championship and I've lost count of how many individual endurance races. All in NA/NB Miatas. IOW, our advice is based on significant personal experience at the pointy end of the field. No conjecture.

A blueprinted/forged 10.0:1, 2.0L NB head BP engine on pump gas and VICS manifold will easily make 160whp for about 200hrs but will need about 15g to run 2hrs on gas. Modified NB tank will hold about 14g lipped full (filler neck full). Need a fuel cell to hold 15g without filling the filler neck or taking 5 minutes to top it without spillage.

Fuel economy being the target however, the answer is that same engine in a very light Miata and detuned to about 135whp. Say 2100# w/ driver. That will be just about as fast but run another 15-20 minutes per stock NB tank. NB tank (bigger) can be retrofitted to an NA with some minor fab work.

 

It seems like a 150 whp (header, tune) VVT 1.8 is the easiest option so far, a little low on power for what we want but seems very "easy" to achieve. Will get a fun car that will provide plenty of track time and can work as a practice HPDE beater as well.
Cams and heads are a lot of points in chumpcar. Also can not do overbore.

One of the ecotec options and manage fuel is also an option. Waiting for the K24a4 to be a popular swap, hopefully that happens next year if someone makes a chumpcar approved kit.

Thanks

 

Can I be the bearer of bad news? Ok, cool.

If you want to win chump races, in all weather conditions, a Honda is the easy button.

Wait. Chump vs champ?

 

Don't hold your breath on the K swaps becoming legal in Champ Car unless you've got some fab skills. Even with the potential swap cost increase to $2500 for 2020, you can't get the basic parts you need from K Miata for less than $2700. That doesn't include the motor and other items you'll have to get to make the swap happen. With Champ Cars eyes on keeping it budget minded, its unlikely you'll see any standard class K swapped Miatas (EC maybe).

 

Yeah, everyone keeps saying champ car, but somehow I don't think they're referring to the open wheel racing series that died in '08.

 

Correct. They're referring to Champ Car, which is the series they're racing in.

 

Oh.

Apparently they changed the name from Chumpcar to Champcar in 2017.

 

Practically fresh as of this morning news!

 

not something I've followed closely, and people commonly mixed them up even before the name change...

My comment was in reply to Ryan's, wouldn't have said anything otherwise.

 

No no, don't let it rub off on you! <3 It was a joke.

 

That's simply not accurate.

 

As an absolute, sure.

But surely someone such as yourself, who is a huge minority even in your own class, recognizes the general statement as being true, right?

 

That isn't accurate either.

The two consistently fastest cars in the class over the last several years are Supercharged.(Well, Matt did try a turbo last year and hated it and went back to a larger blower)

So no, I'm not a huge minority in my own class.

I know this is MiataTurbo.Net.....but there are applications where a Supercharger is not only a workable option but a vastly superior one.

 

That wasn't brought into question. The fact that your car wins doesn't mean the laws of math and statistics no longer apply.

Would YOU recommend a FFS kit for the OP's needs?


[edit]
I now see your edit. You're still not understanding what "minority" means. This thread also isn't about autocross.

 

I have a very clear understanding of math and statics. I also understand physics.

And I am fully aware that it isn't about autocross and nor was my reply directly to the OP. It was to the tool who said the only racing series running blowers is the NHRA and everyone else runs turbos.

Which as I posted....is inaccurate.

 

So, you understand that even in your own class, you're a minority? You seem to be arguing against that. You can either argue against that, OR understand math/statistics, not both.

That "tool," while he broke the first rule of the internet, which is speaking in absolutes, made a generally correct statement.


Your car is awesome, i'll be happy to state that each and every time you post on MT reminding us that you win with a supercharger. It's also an outlier and does not establish any norms.

 

Eric,

We know you take every negative opinion of superchargers personally. Please don't. The context of this thread is wheel to wheel road racing. Superchargers, both PD and centrifugal, have proven inferior to turbos there. Besides results, and as someone else put it out, statistics and physics are not on your side in that argument.