Actual power gains from bolt on parts?

[Tinman]

I'm currently looking to build another FC for NASA PTE, this means getting the best bang for the points out of the 13B. For those not familiar with NASA's Performance Touring rules, here is a brief rundown. Each car is put into a class based on factory performance, N/A FCs are "E" class and turbo FCs are "D" class. Each modification "costs" points and with only 19 points to spend before being bumped up to PTD, each point must be well worth it. After suspension, brake, and tire points I only have 5 or so points left for engine performance.

So the question is which of the following modifications yield the most performance gains either by themselves or in combination with each other?

Air intake system utilizing fresh air from outside the engine bay, 1 point
Catalytic converter deletion, 1 point
Cat back exhaust, 2 points
Header, 2 points
Underdrive pulleys, 1 point

Any actual dyno numbers would be greatly appreciated.

[Ender]

Originally Posted by Tinman

Air intake system utilizing fresh air from outside the engine bay, 1 point
Many people have tried this and it's hard to make worthwhile improvements on the stock intake, turbo or not.
Catalytic converter deletion, 1 point
Should be a huge help, do this for sure. Cats, stock especially, make the engine feel like it's pushing silly putty through a straw.
Cat back exhaust, 2 points
Pretty pointless if you aren't going to pull the cats. If you do pull the cats you would probably gain more from a good header on NA (they are very inefficient), and on turbo if you pull the cats then you'd have either open or a downpipe anyway. A catback is especially helpful in creating power on turbo applications.
Header, 2 points
See above ^^^
Underdrive pulleys, 1 point
Maybe for reliability. If you're revving really high a lot your water pump may cavitate and you can overrun the alternator, but I doubt you'd see much power gain from it.

Any actual dyno numbers would be greatly appreciated.

Comments in red.

I actually had my first dyno run yesterday. Poor conditions, it was cold and raining, and despite replacing my turbo-mani gasket two days ago it might already be leaking again... grrr.

Relevant list: untuned 13Bt, Rtek 1.7 ECU with 720cc secondaries, 10psi max boost using a cheap manual boost controller and cheap BOV (that may or may not leak some...), open 2.5" dp to a y-pipe splitting to two 2" pipes with a muffler on each, no emissions, manual steering, A/C still installed.

Pulled in 4th gear.

[Phoenix7]

I'd use my 5 points on this:
Catalytic converter deletion, 1 point
Cat back exhaust, 2 points (will a single exhaust cost you more points?)
Header, 2 points

Look into the Rtek chip (PM ROEN on here since he has more experience with it) for tunability while maintaining the "stock ECU"

Roen has made as much as 170RWHP out of his NA so you should shoot him a PM and see if he can help you out a bit more.

ENDER: I'm interested to see the dyno results after you tune it. Were you able to get the gasket in time for the dyno?

[Ender]

Yeah, I got the gasket installed Friday night. I took it out to test it and it was beautiful, but after a little while it sounded like I might be leaking a little again and that persisted into the dyno day and so on and so forth. I'm not entirely sure what the deal is, regardless, if it is leaking again I know it's not as bad as it was. The old gasket I pulled out was literally 50% gone and it's not nearly as obnoxiously loud as it used to be.

lol, 1337 posts, Phoenix

[Tinman]

Thanks for the pointers guys, I'm not new to the FC but have very little experience with the rotary engine and it's hard to find good solid info on the 13B with so many morons playing with these.

Next question, I would like to keep power mods to 3 points to allow me to run some 7 point tires. So which is more beneficial header, cat deletion, and stock exhaust or stock manifold, cat deletion, and cat back exhaust?

[Ender]

Originally Posted by Tinman

Next question, I would like to keep power mods to 3 points to allow me to run some 7 point tires. So which is more beneficial header, cat deletion, and stock exhaust or stock manifold, cat deletion, and cat back exhaust?

I'd say the first. I think the biggest restriction on the NA is the cats and I would think the stock manifold is next. Have you ever seen the thing? haha, it's like a long bubble with a small exit hole at one end.

[Tinman]

Yes, the manifold is hideous and factory cats are just as horrid.

Thanks again for the advice.

[TehMonkay]

Racing Beat Road Race exhaust system, or the errr, actaually, there is a better one, but i cant remember the company name, they sell miata and 2nd gen road race parts and rent out road race miatas, and i think theyre in tenesse. they have a road race exhaust system for the fc that is top notch.

[TehMonkay]

http://www.iscracing.net/2nd_Gen_Parts.htm

there, get that one.

[Phoenix7]

get the header, cat-deletion and stock catback for now. You can probably get away with an old HKS catback (larger Diameter than stock but looks stock) though.