S5 NA build

[~Groll69~]

I have an S5 NA motor.  I would like to get 200-250 whp out of it to go into Bella.  I think that is a reasonable goal.  What do i need in order to achieve that. 

I am trying to keep this affordable.

[murz]

Well, I think the cheapest way, with an NA motor is probably Nitrous. If you're willing to take apart the engine though, you could do some porting, porting alone might get you to say 220 whp maximum though, that also requires several other supporting modifications, such as a full exhaust system and intake system, stand alone, or carb even.

[~Groll69~]

220 whp is in my range.  Nitrous would be a fun addition.  I am not opposed to opening the engine and porting it to get there.  If we can push closer to 250 would be best.  I want to do this right. 

[ITSWILL]

I think 200whp is doable easy enough from what I have read. 250whp is upgraded turbo range.

like Murz said, you are looking at a new intake system as well as a standalone or carburetor.  all of this for more money to make less power under the curve than a turbo swap.

best bet for NA would be to half bridge port the motor. put some new 2 piece apex seals in it, turbo II injectors and a megasquirt.

[murz]

After hearing Jake's half bridgeport at LBI this weekend, I think you should go bridgeport, that was the best sounding car there, by far. He's running stock ECU and stock intake, but he's got a decent exhaust on it, so he's probably not making more power than the stock engine configuration. The stock intake is just too narrow and too long for the power-band a bridgeport wants, even the S5 intake isn't that great.

If you get the same intake Will has (for the half bridge build) costs around $300-$400 I believe, find a used Megasquirt for $200-800  from what I've seen and heard.
You already have a header, but with that overlap you'd need a full header back exhaust as well. Say $1000? Or you could have a custom exhaust made, such as a long primary system, or a super short primary system.
Then there comes the wiring install, and Turbo 2 injectors (I might have a set actually you could have).
I'd throw in a walbro as well, or a turbo fuel pump. I think I have a spare you could also have.

I'm probably missing something, but i'm not sure how well the stock clutch, NA trans or rear end would hold up? I'm sure they'd be fine at 200whp, but your call.

[~Groll69~]

I will need help with the work and staying on track to get the parts.  Especially with everything that is going on in my life so far.  I want to do this and move forward on it.  Lets list out exactly what i Need and I will start to get it.  Also when we can do what.  In this effort will be a repaint of the engine bay.  If i can get a plan of action laid out, then i can move on it.

[ITSWILL]

he will need a throttle body as well of he is going to do fuel injection.

also to be sure it would take the power it would need a TII trans and rear end.

I would not recommend this.

I would talk to to Andrew about buying his vert and turbo swap parts.

[murz]

Yep, totally missed the throttle body.
So...

Intake - $500
Exhaust - $1000
ECU - $800
TB - $400
Engine seals - $600?
This is looking around $3000 to $4000, and perhaps less if you get a better deal, but it's done right.

How much is Andrew selling his engine setup for?

[~Groll69~]

I think the $3k-$4K is quite high.  I would think i could do it closer to $1.5K for it all.  What parts are reusable verse new is the big question.  Probably just a seal kit and new apex seals.  Side seals are probably good, though new would be better.  Might be able to find cheaper along with throttle body or what needs to be modified to work.  If i go turbo, then i might as well push for 350-400whp, but i want to keep the cruiser at around 200-250 whp.  I don't think the trans or rear end need to be upgraded for that whp.  250 seems to be the mark that requires upgrade of the trans and diff.

[murz]

Honestly, you could just throw a nice full header to muffer exhaust on the S5 engine, such as the Racing beat exhaust. And call it good. Or go another step and throw an ECU on it, and give it a tune, there are people that hit 200whp on stock ported 6 ports as well. Save the rest of the funds for your other project, and slowly build that up. That's $1000 - $1500 right there, and the car would wake up a bit, and sound 100 times better.

[awfc3s]

I'm not splitting up my setup. I'd like to sell the whole car. As it sits not running I'd sell it for $3,500. If I get it running and put a new top on it then it'll probably go for closer to $5,000.

[ITSWILL]

absolute cheapest way I can think to do it would be this.

4 barrel intake manifold (needs additional porting)$260
fitech throttle body injection (need no ecu
or injectors) $800
Atkins rebuild kit $350
Mazda Apex seals $350
used Distributor, new cap and rotor and wires $100
real racing exhaust and header (fyi this car is going to be loud) $1000
Solid engine mounts $40
Walbro 255 $100
spark plugs $40

That's $3040... not including shipping.

And the clutch may slip and the transmission will probably take a shit after a couple years. And you should also put a good koyo radiator on there and an Efan.

[awfc3s]

Or for another $460 you can buy my turbo swapped vert.

[toplessFC3Sman]

If the goal is to stay NA, then I'd say that the most essential things to make high power will be:
1) long-primary exhaust headers to prevent exhaust pulses from one rotor from increasing residual and hurting volumetric efficiency in the other rotor
2) RX-8 e-shaft and stat gears to safely run to 9000 RPM all day long. The RX-8 rotors would get you to 10:1 CR from 9.7 for the S5 NA, but that's probably not worth the extra expense/hassle to machine them for earlier-style apex seals to deal with the peripheral exhaust ports.
3) Slightly later intake closing on the secondary runners/ports, possibly a half-bridge for more ram-air effect at high speed, and slightly earlier exhaust opening for a stronger blow-down to help exhaust extraction since the pulse won't hurt the other rotor with long exhaust headers. Since this is still a 'vert, with the extra weight and top-down cruising criteria (ok, I'm kind-of assuming that last bit), I wouldn't increase the exhaust overlap much, if at all, so you don't have trouble at low speeds/low loads/idle.

If you're aiming for 200+ hp, I would say that the focus should be on high RPM air flow, as long as it isn't compromising the low-speed drivability. For that reason, I wouldn't touch the exhaust closing or intake opening port timings, and would probably do only minor porting to the intake manifold and throttle body. Of course, opening up the intake pre-throttle and the exhaust after the long-primary header. For this, the stock MAF and ECU may get you close, but would probably clip the high RPM power through the rev limiter, non-ideal spark map for the mods, and through the MAF topping out.

A MAP-based ECU like a Megasquirt would be better as it would remove the MAF's flapper and smaller diameter from the intake system, allowing it to be opened up further, and it would allow more aggressive AFR & spark timing. I'm a big fan of the megasquirt, but they certainly require a lot of electronic comprehension, learning, and some patience in dealing with an open-source community vs a customer-focused company, and they aren't for everyone.

Supporting mods like a good radiator, making sure all the plastics are in place for good oil cooler and radiator air flow, and a bigger fuel pump and injectors (S4 or S5 TII should be more than enough) would also be in the cards.

Now, whether all of this is worth it vs a turbo-swap to get similar power but more torque... well, its a project and many times the decisions are made by the head & the heart, not just what is logical or most cost-effective...