Will I love a supercharged mx5?!?

[torqueofthedevil]

I have my eye on one at the moment and have wanted one for ages. It's an NA8.

I currently have an NA6 and whilst its not even in the best condition, it never fails to put a smile in my face and just love the reviness of the engine.

I'd have to sell it for the s/c model and I'm sure it'll be the right decision but would like to hear from others who have made the change!

[spoodler]

Never owned a supercharged MX5 so can't compare...
What I would say is that what you have asked is a very open question. If what you love about your current car is that it owes you three hundred quid, does forty to the gallon, lacks the power to wear anything out and you can abuse it and leave it anywhere without worry then a five grand, immaculate thirstier supercharged example might be everything you don't want... I've had cars from 602cc to 6600cc and some of the most keenly missed have been the most simple and cheap. I'm not saying that your car is a three hundred quid example - hopefully you see my point tho'.
On the other hand, if you just love your car but "need" a supercharger... and if you feel you preferred the n.a. version then sell up and get another.

[Nikko 40691]

What makes you want s/c over turbo?

[Nikko 40691]

What makes you want s/c over turbo?

[papahet]

WeirdNeville said:

You should do. Retains the throttle response, makes the rear end very throttle steerable, they're just a great laugh when supercharged. Gives them the oomph they need to go from "fun little roadster" to "Properly quick sportscar".

I hussled a timidly driven Ferrari 430 round Silverstone in one, which was a great laugh, and currently co-drive one in a tarmac rally.

Here's some on board action:

http://www.youtube.com/watch?v=3KV2i6ZkMyY

http://www.youtube.com/watch?v=LZYoUfe5res

You won't regret it. Just make sure it's properly converted and the mapping is good. The one I drove at Silverstone has been supercharged to 200bhp for about 8 years and 50k+ miles with no additional issues.

This is my car. Rally series starts again in November

It has a Rotrex C30-74 and currently only blows about 6.5psi and 150BHP at the wheels. It is held back by a tune that is over fuelling it, there would be another easy 20BHP in a tune.

If I chuck a proper ECU, set of 550cc injectors and a 150mm crank pulley on it then it will push 12psi and an easy 220BHP at the wheels. The C30-74 is good for 350BHP which is way beyond what a stock MX5 engine will handle.

Nikko 40691 said:

What makes you want s/c over turbo?

I have owned a turbo Mk1 road car with 220BHP at the wheels, turbo MK2 race car with a built engine and 250-260BHP and this current car with its Rotrex and 150BHP.

The Rotrex car is the sweetest to drive. Throttle response has not changed at all, the turbo cars have a certain 'fluffiness' about the part throttle response that you have to drive around. The turbo will pull harder all the way to the redline but the supercharger will have a more linear power delivery across more of the rev range.

[T0MMY]

Not sure if your question is about whether the extra power of FI improves an MX5 or about the comparison between turbos and superchargers.

On the road, the extra power is good fun, makes it far far easier to overtake and it's always entertaining when some knob in an Audi tries to push in front of you off a traffic light Overall though I think it takes away some of the purity of these cars and I slightly regret turboing mine as it's gone from being something I can thrash round a race track all day with no major mods needed and total reliability to a car I have to constantly worry about blowing up with all the extra temperature etc. Suddenly you need bigger rad, intercooler, oil cooler, various gauges etc.

If it's purely a road car I'd go for it but if you want to do trackdays in it I'd think twice about it unless you're happy to spend a lot more cash to keep it reliable. It's definitely a better road car with a bit more oomph though.

Edited by T0MMY on Saturday 14th September 17:31

[J-Tuner]

If you have never experienced a supercharged car first hand then you are in for a treat. My first experience happened to be a mini JC Works and ever since my mate buzzed me in my mx5 on the motorway with the charger whine being audible from behind and then the pops and cracks on overrun as he let off past - i was sold.

I'm running a Intercooled JR setup with crank overlay, injectors, megasquirt and a few other bits. Its utterly superb. That said once you have started down the path it can be a slippery slope. The initial rolling road tune revealed the above mods were netting me about 160BHP at the wheels at 6 psi or there abouts. I am expecting more to be honest so its going back for more tuning as i have fitted a new exhaust and intake since...

Its completely fine to live with daily - the MPG is actually better unless you thrash it relentlessly, and of course you have the noise. I have people looking in their rear view mirror at me on the motorway as they can actually hear the supercharger whine from inside their cars haha. i will say though that it requires respect now - it can bite a lot more easy now if you take any liberties. But that thats part of the appeal for me as well.

[J-Tuner]

If you have never experienced a supercharged car first hand then you are in for a treat. My first experience happened to be a mini JC Works and ever since my mate buzzed me in my mx5 on the motorway with the charger whine being audible from behind and then the pops and cracks on overrun as he let off past - i was sold.

I'm running a Intercooled JR setup with crank overlay, injectors, megasquirt and a few other bits. Its utterly superb. That said once you have started down the path it can be a slippery slope. The initial rolling road tune revealed the above mods were netting me about 160BHP at the wheels at 6 psi or there abouts. I am expecting more to be honest so its going back for more tuning as i have fitted a new exhaust and intake since...

Its completely fine to live with daily - the MPG is actually better unless you thrash it relentlessly, and of course you have the noise. I have people looking in their rear view mirror at me on the motorway as they can actually hear the supercharger whine from inside their cars haha. i will say though that it requires respect now - it can bite a lot more easy now if you take any liberties. But that thats part of the appeal for me as well.

Edited by J-Tuner on Friday 20th September 13:24

[J-Tuner]

If you have never experienced a supercharged car first hand then you are in for a treat. My first experience happened to be a mini JC Works and ever since my mate buzzed me in my mx5 on the motorway with the charger whine being audible from behind and then the pops and cracks on overrun as he let off past - i was sold.

I'm running a Intercooled JR setup with crank overlay, injectors, megasquirt and a few other bits. Its utterly superb. That said once you have started down the path it can be a slippery slope. The initial rolling road tune revealed the above mods were netting me about 160BHP at the wheels at 6 psi or there abouts. I am expecting more to be honest so its going back for more tuning as i have fitted a new exhaust and intake since...

Its completely fine to live with daily - the MPG is actually better unless you thrash it relentlessly, and of course you have the noise. I have people looking in their rear view mirror at me on the motorway as they can actually hear the supercharger wind from inside their cars haha. i will say though that it requires respect now - it can bite a lot more easy now if you take any liberties. But that thats part of the appeal for me as well.

[Bomberharris]

The question is where to get a decent supercharged one?

Get BBR to make one...............

Keep looking at Nutz etc

Make one yourself?

[T0MMY]

Don't know about superchargers but turbocharging one isn't that hard. I did mine for £1200 with a new HKS kit and some other bits I added and it would have been a hell of a lot cheaper if I was less lazy and spent the time to find second hand bits. Problem is mine is a 1.8 and you could be looking for years to get a decent used manifold and downpipe (I was). Much easier with a 1.6.

DIYing has the advantage of avoiding the issue of not knowing exactly what has been done and it's quite satisfying as a project given the massive difference it makes.

[J-Tuner]

Bomberharris said:

The question is where to get a decent supercharged one?

Get BBR to make one...............

Keep looking at Nutz etc

Make one yourself?

That all depends. You can buy them already done but you will pay good money as they are fairly rare and the rest of the car will have a say in whether its the car for you.

You can cobble together a mini charger kit and install on the car but you will need to get involved and have a good understanding of what you need and how it will all go together. If done well there is no reason why this cant be a powerful and reliable solution. I've read that the mini setup actually can make more power over the JR setup. It just requires some effort on your part and maybe some aggro getting it fitted nicely. There will be niggles that will take weeks to sort out though - don't be under any illusions haha

Or you can do what i did and get the complete JR kit. You have to be patient but there are kits out there to be had. Mine is a 1.8 and is harder to get a complete kit for, but they are out there. You will have a slightly easier time with a 1.6 but you then miss out on fthe 1.8 brakes and chassis bracing. Something to consider. I actually bought my kit from someone on here who contacted me after i put a shout out. I got the full kit and it was in excellent condition. I got skuzzle motorsport to fit mine but i have since taken the charger off and got my hands dirty. Its a piece of piss to install now i understand whats going on. I still had my fair share of niggles - its been a rollercoaster journey but i think its getting to the stage where its relatively settled now.

You can do these things relative cheap with a basic fuelling setup, or you can spend some cash and get a fully mapped custom setup, it really all depends on what you want and what your budget is. I went for the latter since i didn't feel confident in doing a lot of it myself, and the end product is superb. Its not for the faint of heart or wallet though. People will think you are mad messing with the car, You only live once so if its what you want go for it and sod the rest. Its worth it

Edited by J-Tuner on Sunday 22 September 17:55

[T0MMY]

From what I can tell supercharging is a bit more involved which is why I went the turbo route, although I think the former might make for a better drive. I have a very basic low boost set up with just the HKS F-CON to control fuel and timing and it ran perfectly right from the off. It's not massively quick but ample given the weight. No idea on the power exactly but it's quicker than an E46 330i...the guy tried twice just to make sure

[J-Tuner]

if you mean more involved mechanically - i think they tend to even themselves out to be honest. The main pain in the ass with the charging route from what i have experienced is the initial belt alignment, sourcing a decent tensioner, and then finding the correct size belt for your application. Too long and it risks fouling itself, to short you will strain the bearing on the tensioner, a few mm out and it will work but have minor slippage what will be difficult to detect but will have you eating belts reguarly.

As an example - i recently fitted a new belt that was ever so slightly smaller, i then started to dump boost to the extent that i thought there was a problem. Just turns out i had fixed a belt slip issue i didn't know about hehe

With turbos you have to worry about manfold fitment and possible splitting if you get a cheapo one, oil/water feeds (tapping the sump which can be a bit daunting).

Swings and roundabouts - i would definitely let the character dictate which way you want to go. Turbo for more outright power and the surge of boost. Or always on power (more in keeping with the N/A character of the car IMO) and loads of visceral charger noise.

Each to their own.

[T0MMY]

Yeah, I meant more involved to fit and get working maybe, although I could be wrong. Turbo is pretty easy really, just swapping the mani and downpipe then a few sundries. I do think I'd prefer a supercharger but my turbo bits popped up for sale on MX5Nutz at a good price so I just couldn't say no. With a smallish turbo and low boost the lag isn't a problem but you do get the situation where the car has loads of midrange and tails off slightly (or rather stops building power as quickly) at the top end, which isn't so sporty in a way, despite being massively faster than standard.

[J-Tuner]

I'm sure it will be great fun to drive as well. And you are right about the lag - its not that much of an issue with a small matched turbo. Better to have something thats right for the characteristics of the engine than whack a bloody great big truck turbo and get everything at once and make it unrewarding to drive.

Just to give you an idea here is my initial rolling road map with the charger on. Figures are at the wheels :



Green lines are my car as standard. Red lines are with the charger on and an initial very conservative tune.

You can see its not far from the standard characterisics, theres just more of it and perhaps a bit smoother throughout. Peak power is right at the end of the rev band.

[T0MMY]

That looks good Never dynoed mine but I imagine it would tail off a bit at the top as the airflow through the turbo becomes a bit limiting. I'd love to have a shot in a S/C one but it's not like I'm going to rip the turbo off and start again so I guess it's better not to know if I prefer it

Quite interesting looking at the graph for the NA engine. I've always thought the engine in the MX5 is totally unsuited to the car as everything else about it is so sporty except the power delivery. I don't mean the lack of power, more how/where the power is delivered. It just doesn't feel like it wants to be bounced off the limiter in every gear which is how it should feel in my opinion.

Edited by T0MMY on Wednesday 25th September 22:08

[J-Tuner]

Really? thats interesting. Although personally i find the standard 1.8 adequate when crusing around (the extra torque makes it a bit more easier to be lazy) once you get past 4.5 grand it does feel like its "on the boil". Sure there is plenty of noise as well and it feels like the pistons are going to exit the block but it actually loves getting driven hard. Mine was actually sluggish and slow when i first bought it as it never got driven in anger. I noticed a definite improvement in performance as it started to give it some stick, combined with a decent service.

You know these engines are over-engineered in standard form - i believe they are based on the mazda 323 turbo engine, which is the reason why they respond so well to FI. Someone correct me if i am wrong