Rochhe

Hey rotary family,

I have a long and complicated question and welcome all insight and knowledge. I am currently building a 13B-REW engine to possibly be naturally aspirated. I am building for a racing league where my peak WHP is around ~200WHP. I am keeping the engine stock ported (brand new from Mazda) and wont do porting until I receive my second engine. So as of right now with stock porting I have three setups that I am debating on, and would like advice if there is something better/more efficient.

Choice One (Most expensive but seems best):
-Stock 13B-REW engine
-Pro-Series IDA throttle body kit (includes fuel rail, manifold, throttle body and air box)

Choice Two (cheapest but if it works it works):
-Stock 13B-REW Engine
-Speedmaster 4-barrel intake manifold
-Speedmaster 4150 throttle body
-Extreme Velocity Carb hat
-External fuel rail w/ injectors

Choice Three:
-Stock 13B-REW Engine
-Speedmaster 4-barrel intake manifold
-MPFI Race Throttle Body
-Custom Carb Hat
-External fuel rails w /injectors

Please keep in mind I will port my second engine (PP) and leaving this one stock, so trying to exceed or get to 200WHP with a N/A set-up. I need custom headers as well so if anyone has ideas I'm open, or ill get them made. Anything I am missing? I have a PowerFC but moving to a haltech 1500 most likely. And I will be attempting to find 4.77 rear end gears.

Thanks!

WJM ROTARIES

Dont waste your money go with the IDA throttle body set up it will give you the best setup for both engines

fidelity101

iTrader: (11)

a streetport would help but all of those setups would get you 200hp

Rochhe

That's looking to be my route, I have seen good reviews on it. Just trying to figure out what manifold works with the REW. Giving them a call and figuring out details.

Rochhe

I will be Peripheral Porting my second engine coming in, I just dont want to open this one so I can do some testing. But definitely noted haha.

BLUE TII

iTrader: (9)

If you will be running peripheral port naturally aspirated on your next motor the IDA throttlebody makes the most sense since it can be used for that motor as well.

If you were considering going turbo 13B later the 4150 style manifold would make the most sense.

Have you gotten your Mazda Motorsports sponsorship yet? I think its down to just one race/track/etc result now for tje discount on Mazda and Mazda Competition parts?

Have you looked into availability of the Mazda Factory Race 13B peripheral port rotor housings?

Rochhe

I think I will go with the IDA, seems like a nice all in one set-up. I haven't yet, been looking into it. Guess ill try sending in some time slips and history to try to get on board, been ordering most my stuff through Ray Crowe.

BLUE TII

iTrader: (9)

Inspirational post

Leadfoot Festival (NZ, Rod Millen's driveway "Goodwood") in 2008 an NA 13B-REW FD.

TeamRX8

iTrader: (2)

^^according to the comments, that’s 300 hp fwiw

how about an explanation on the stated “200 hp” goal?

is that some kind of imposed limit by the rule allowances that can’t be exceeded or where exactly did that come from? What racing league are you speaking about specifically?

In order to either provide or receive proper answers, a proper understanding of the question being asked is required.

ps; a new REW engine has a racing part no. at Mazda Motorsports and is listed in the race parts category area. Purchasing racing parts doesn’t require race results. You only need those to purchase OEM parts from Motorsports. Anybody in the USA can purchase race parts from them. They will not ship outside the USA.
.

BLUE TII

iTrader: (9)

A "budget" track NA FD.

13B-REW based peripheral port

Note: explanation on the gearing issues. 4.78:1 rear gear from RX-8 is the cheapest solution.

Then you will be shopping for an alternative to stock gearbox. Not only does the stock FD gearbox have long ratios, it soaks up about 40rwhp at high rpm and that is a lot on an NA build.

Even in a hp limited class all that high rpm hp loss is from friction and friction creates heat which kills the FD transmission at high rpm track use.

________
The real "budget" race build is-
A 200hp stock "block" single turbo build with an unusual focus on engine weight savings and simplicity as I oulined in your earlier thread.
This will keep your revs lower while having a broader power band.

This would allow keeping the stock FD gearbox happy with just a transmission cooler.

______

You can still reach 200hp peak hp and get out on track with a stock block Naturally Aspirated set-up and shake the chassis down this comming season with the turbo friendly budget intake (4150 non-injector TB & big primary injectors).

Is this a $40,000 build or more a $200,000 build?

BLUE TII

iTrader: (9)

^^^
We need to know race organization and class.

I was just looking at NASA ST and they specify Dynojet for RWD dyno testing.

If this is the case and you are in a class that allows unlimited wheel/tire you need to work with the FD innate advantages and soak up power loss on Dynojet in a big wheel/tire combo that will help braking and cornering too.

You can fit 18x12 +30 and 335/30-18 front and rear with your bodywork.

FD represents brute force not finess in the context of a 200hp racing class, embrace that if possible.

j9fd3s

iTrader: (3)

the dynojet in Norcal is capricious and evil, and you NEED some way to dial up or down the hp. the dyno is on a truck outside, so the difference in weather between a foggy morning and 100f afternoon is pretty big (or the dyno really just sucks, we saw a guy with an S4 Vette gain 12hp per dyno run for 5-6 runs in a row, then they switched to the other dyno and it did it for another 3-4 runs. we had our run and tested low, died of relief and then went racing)
so turbo would be nice for this, because you can go to your tuner and do a boost per hp map, and if you dyno high you can lower it or vice versa.

BLUE TII

iTrader: (9)

For turbo set- up one could have the electronic wastegates mapped to a driveshaft torque output sensor for repeatable HP output no matter the conditions.

A very good idea since your typical turbo set up loses 30-40hp once the IC is heatsoaked. Might as well race with the full 200hp you dynoed with when everything was nice and cooled off.

I guess for NA one could have drive by wire throttle body mapped to the torque sensor as well, its just 200hp comes later in the rpms on an NA or not at all.

Rochhe

It's a power to weight class. Gridlife touring Cup. 15 minute sprint racing.
Looking into FEED's 4.7 gearing package right now.

The racing is 15 minute sprints but I understand what you are saying about the transmission heating, ill look into it.

In regards to the budget, I'm just racing to have fun. No I don't want to spend even near 100k into this, but I also will be spending money over time and just want an idea for the best route. I'm spending most of it on the initial set up and then trickling along. As I said this is all for fun, so if I think of having a budget in racing.. well I shouldn't be racing.

GLTC and my wheels are currently 18x10. Technically I could go 18x12 but the most tire I can fit is based on weight which at the moment puts me around 245/35/18 to 265/40/18 (low to high).

fidelity101

iTrader: (11)

try and find some 4.90s or 5.10/5.12s and look for an rx8 S2 gearbox to really get that last ounce out if possible.

BLUE TII

iTrader: (9)

I dont know how much Feed charges, but the RX-8 4.78:1 ring and pinion is $632 from Mazda Motorsports.

Sounds like Grid Life Touring Car series is really going to be about reliability, chassis set-up and driver since they regulate power/weight/tire width so closely.

I keep thinking an RX-8 would be a better chassis to race over the FD.

You could be so much more aggressive with car placement since its easily replaceable/repairable and its a more stable long wheelbase platform for when other drivers get aggressive with you.

The RX-8 chassis is better handling/balanced with the engine and trans lower and further back and the gas tank(s) moved ahead of the rear axle as well as a more rigid unibody.

If you get a blown engine S2 RX-8 you already have the transmission and rear end you will want for NA, you can just get the 13B-REW swap parts to use your engines or a traditional 13B NA or turbo race engine.

RX-8 wear items are much cheaper and available at local chain stores as well as plentiful in wrecking yards.

The FD is beautiful and it would be cool to see it out there racing still, but in my opinion FD would be a better car for the Grid Life time attack classes than wheel to wheel very regulated GLTC series.

gracer7-rx7

iTrader: (16)

https://www.mazdamotorsports.com/faqs/
You do not need current race results to get membership to Mazda Motorsports if you are still building the car.
Sign up. Parts are cheaper than Ray. Often best to call to place an order if you can't find the part yourself. Bunch of real friendly guys there.

Rochhe

how difficult is the gearbox swap? Like custom driveshaft or pretty simple swap?

That's way cheaper than the FEED 4.7. Ended up creating a mazda motorsports account and looking into it.

Also as much as I appreciate your RX8 advice, I'm racing my FD. Is it expensive? YUP. Is it impractical? YUP. But is it fun? HELL YUP. And that's why I'm doing it. I don't plan to win, I plan to have fun. I do appreciate all the insight though!

Created my account, definitely buying all the goodies. Thanks!

j9fd3s

iTrader: (3)

+1 there was a local car here and its been a while, but with limited prep (225 tires, shocks, springs, catback) it was really fast

fidelity101

iTrader: (11)

because of the PPF you will need some sort of trans mount and likely a new diff mount which is the hardest part. you can likely get away with an automatic driveshaft or worse case you only need to shorten it less than 1" which is very easy to do at a driveshaft shop. the slave cylinder is from any b18 honda and you basically just need to do a custom line or hose from the clutch master to the clutch slave cylinder. very easy - take a look at the 2009+ rx8 gearing and input your tire diameter you will see the speeds more 3rd/4th gear friendly.

the bell housing bolts up but you cant use the rx8 slave cylinder because it hits the rear iron oil pedestal casting. you need an rx8 starter and rx8 bellhousing bolts (they are longer) and the FD/FC t2 clutches are the same as the rx8. just be mindful of your throwout bearing depending on what trans you have and thats about it. I think they are only rated to 380-400 ish hp which is plenty fine for NA rotary motorsports use.

peejay

Honestly I'd be curious about swapping in a Miata 5 speed transmission with an N/A RX-7 bellhousing/shortened input shaft. Less parasitic loss, lighter, better heat resistance, smaller clutch and flywheel.


An aside. I bought some engine parts from a racer who wanted to sell me a complete set of FD housings for $1500. The problem was that they were bridge ported into the water seal, and his racing class used a restrictor, and large bridge ports do not work well with any kind of intake vacuum such as what a restrictor would create. So he was moving back to a more mildly ported engine. I would expect that a peripheral port would be just as sensitive to intake vacuum if not more sensitive.

I didn't buy them because all of the oil passages were altered for use with a dry sump setup, and it would be kind of a pain to deconvert it. Also, I'd just gone and had my own bridge ported side housings redone by Chips and bought a new set of rotor housings from Mazda, oddly enough spending just under $1500, so it was a case of "where was this deal six months ago???"

j9fd3s

iTrader: (3)

i was going to say that, but like i got my 20b turbo to dyno 139rwhp, so i think i could do it.....

any tuner that isn't a plank would limit the rpm, so if you made 300hp@9000rpm, you'd just lower the redline until it worked.

peejay

Well there is that, but there is something to be said for an engine that makes 200hp at 6000rpm as well as 200hp at 9000rpm. You would be driving a solid wall of 200hp, no points below that. This would accelerate a lot better than an engine that had you cut the party at 6000.

WRC engines accelerated so well because they may have been limited to 300-340hp or so but they made that power literally everywhere. So you could drive at low RPM where you were making 25 pounds of boost (and all the lag because of the 5:1 pressure ratio in the turbo to get there) or you could drive at high RPM where you were making 6psi boost...

Gilgamesh

Stock NA rew with rew intakes is probably in the 180 range easy. It will also be the quickest and most reliable way to get on track for your first season.

Then you can worry about optimizing your set up

mustanghammer

iTrader: (3)

I looked into Grid Life with my car. HP is not an issue for me (204hp with a street ported 13B) and I like the 200 wear tires from a cost perspective. The negative, other than the fact that their races are only local to me once a year is the amount weight I would need to add.

Grid Life also have some interesting dyno rules. For example engines that have a really flat power curve are likely to get a lead trophy over and above the normal power to weight formula.