NA Screamer

[Sean]

My current set-up

Before you do anything else, spend a few dollars (probably less than $100) and get a fan on the back of the radiator to keep it at decent temps.

The air con fan won't be helping too much too often...

[Fatty]

hey sean, ploise exlpoin. i thought most of our cars have 2 fans on there already? i've heard that many people wire them both in series when they put a turbo on, to aid the cooling.

[DOYLMX5]

yeah there is a fan there. it just isn't wired up in the traditional way (a dodgy from before the car's time with me).
never gotten around to changing it.

But seriously, what can people tell me about quad throttle bodies? and cams etc??

[Fatty]

But seriously, what can people tell me about quad throttle bodies? and cams etc??

i can tell you that it'll cost a lot more and get you less power than a turbo install.

serioulsy it isn't that hard to throw together something nice for 2 or 3 grand.

[DOYLMX5]

Yeah that seems to be the talk around the town.
Money saving time!!

[Sheck]

Ok from what i can tell, if you go for huge cams and quad throttles you could get around 150hp out of the engine. But i'm talking like 304deg duration and prolly close to 10mm lift. Then you need all the supporting mods - first thing will be a computer so you can run the quads (you'll need this no matter how far you go) the stock pump should be able to handle it and as long as the quads you get have all the injectors and fuel rail and TPS etc you wont need anything else.
Cams - these are easy to install but if your goin for some wild one then you'll need to rebuild the engine with forgies etc or if you wanna cheap out you could do just the head, which will be neccesary, and get at least solid lifters and stiffer springs. But while your in there you may as well clean it all up and get it ported etc.

If your going for mild cams then most will just be blot in with nothing else needed. I'm running HKS 264 deg cams with about 9mm lift and stock everything else (apart form the turbo kit) and it went ok - would of been hell fun in an N/A but i had to get cam gears to tune some more midrange back into the thing.

Oh but from mild cams you wont see much hp gain, you could prolly see 10hp from them. 10-20hp from an exhaust and filter, 10 from a computer, and maybe 10 again from quads. So about 50hp for around $5000 depending on what you go for.

If anyone else has anything helpful to the original question then chime in.

Dave

[Babalouie]

I would really like to hear some actually answer the question to this post as to what you could build and provide some specs. I am sick to death of the answer everyone saying 'add a turbo' - a turbo is not the be all of power and is to me a 'cheap fix' bandaid solution.

Having owned a turbo car and dríven many others, they just don't do it for me. I dislike turbo's in the way they deliver their power and anyone who has dríven a well setup N/A car can vouch how good they really are.

Well, as for a "stage 1" BP build, these are the prices and specs for my motor:

2002+ 10:1 NB8B pistons: $650
20 thou head shave (adds 0.5:1) + reco: $900
Engine gasket Kit: $400
General rebuilding labour: $1200
Tomei 252/254 cams: $750
Toda cam gears not really needed): $300

I added these to my engine, which already had the usual breathing mods and a piggyback computer, result was 90rwkw. Not as powerful as a turbo but yeah, it's pretty nice, very responsive. Redline is stock, and the powerband is still going at 7000rpm. If I could raise the redline by 500rpm the powerband would be able to reach its natural conclusion, but I'm happy with it, it's nice and rorty and suits the character of the car.

Adding quad throttles and porting the head would cost thousands more and add maybe 10rwkw but the response and the sound is what the extra dosh would be paying for, not peak power.

[mr_rotary]

Cheers Babalouie - that's the sort of answer we need more of

As for adding a computer, they are not as expensive as what a lot of people make them out to be, you can pick up a relative modern Microtech for approx $300-$500 plus wiring loom and tuning. For quad throttle bodies, why go for the pricey injection perfection bodies when there are affordable quad throttle bodies off the 4AGE20V or even off a road bike which can be had for approx. $300. Downside is the manifold will be custom made to fit the application however it shouldn't be too hard.....

I have been 'toying' with the above idea as I already have a Microtech laying about and can pick up the quads for a small amount.

[yarnmx5]

Well I did go the NA6 NA route with highly modified head converted to soild lifters, custom cams (similar profile to that of a BDA lotus), microtech, modified intake, etc.

All up it probably cost me $5k....and I bought the engine off of a crashed race car.

I no longer have any of this on the car....why you ask?

Well it make 87rwkw at 6800rpm which was good for standard injection and inlet manifold, but I wanted a car that was streetable and quick on a race track.....MY MISTAKE! Firstly it sounded like a moderately ported rotary, it had nothing and I mean nothing under 3000 and it ran out of fuel at 7500rpm. I needed quads or bigger injectors etc... And loud...I remember sitting at the lights looking up at a landcruiser and the passenger shaking his head at me...I felt like a hottie (no comments please).

Basically I spat the chewy and took it all off. sold the ecu, head/cams. why not change the cams? well the standard cams would no longer fit because of all the head mods to fit the larger lobes I think (PS dont ask me cos I'm not that mechanically minded)so I had to put a standard head back on. Not usually a problem but I had already sold my old engine.

To cut a long story short....unless you have a 1.8 litre or stroker engine...dont bother (unless trying to fit into a particular class). I I had my time again, I would go straight to forced induction.

But hey, thats just my opinion, good luck with the quest.

[Babalouie]

I had used 272 cams on a 4AGE before and it was just like Yarnmx5's experience. So when it came time to get cams for the MX5, I went for mild cams like the Tomei Poncams instead of the big \"matchbox\" cams. The Poncams are big on lift (9.2mm) but conservative on duration. They're not a big increase in power tho, only 8rwkw.

I think the higher compression and the extra capacity helps a lot too, my motor can idle along at walking pace in 2nd gear without hiccupping, idles at 750rpm and handles the a/c just like a stock car. I would say that torque is slightly diminished below 2500rpm but above that it's about the same until 4500 and then it gets a second wind and goes.

Remember, BP engines aren't Honda motors...no point having 8000rpm cams if we can only rev to 7000 With our engines, Stage 3 isn't necessarily better than Stage 1

[adamjp]

I'm with Mr Rotary and Babalouie here.

The major problem most FI adherents don't talk about is the insurance and registration issues. Last time I talked with any mainstream insurance company about converting a car to FI, they indicated a substantial increase in the bill.

So don't telll them? Don't expect to have your insurance claim for an accident honoured.

Yes for your $3k you will get more power from a puffer, but you also get to keep on paying, at the pump, at the insurer and , if not done right, also at the defect fund raiser run by the police.

A bumpier set of cams, exhaust and computer is totally stealth.

I must also admit I sold a full house V8 to go to the MX5. One of the reasons was I just didn't want to go that fast any more. Big power is not my passion any more. If you want that, a puffer is the best way to go.

[mr_rotary]

Yes, insurance does rise considerably with FI. I was going to purchase the white turbo MX-5 in WA years ago from the original owner as I had helped with the conversion, however insurance was $400 per year for stock vs. $900+ for turbo. Oh and that's from a 'select' few that would actually insure you.

[CT]

If you want to got NA nuts - go shopping for this......

11.1 comp pistons
40thou head shave
extensive porting - flowed 260hp
solid shim under bucket lifter conversion - custom made
~292deg cams 11mm lift
lightweight valves, retainers and springs
20thou block deck
2mm overbore
modified oil galleries
Carillo A beams
arp main and head stud, heavy duty mains caps
knife edged lightened crank
48mm quad throttles
custom short runner manifold
ECU
= 125rwkw in an early 1.8 It had potential to get up to around 130rwkw with better exhaust system but that gives you an idea of how serious you have to be.

Buy a turbo, insure with shannons and you'll be miles ahead.

[4sfed5]

I added these to my engine, which already had the usual breathing mods and a piggyback computer, result was 90rwkw. Not as powerful as a turbo but yeah, it's pretty nice, very responsive. Redline is stock, and the powerband is still going at 7000rpm. If I could raise the redline by 500rpm the powerband would be able to reach its natural conclusion, but I'm happy with it, it's nice and rorty and suits the character of the car.

if you want to raise the redline you can change the timing crystal in the ECU which changes the time reference that the ecu uses to judge RPM.....eg on the early 1600 cars you can change the crystal from a 4 Mega hertz chip to a 4.4 Megahertz chip.....this will raise the redline by 10% (think about it, thats nearly 8000rpm redline!!) and also lean out the mixtures by 10%.

The chips are easily available from jaycar for only a couple of bucks.

[4sfed5]

Yes, insurance does rise considerably with FI. I was going to purchase the white turbo MX-5 in WA years ago from the original owner as I had helped with the conversion, however insurance was $400 per year for stock vs. $900+ for turbo. Oh and that's from a 'select' few that would actually insure you.

so thats 10 bucks a week to have a turbo screamer........i think i can go without the movies for that!