Turbo vs supercharged mx5 on Mighty Car Mods!

[captaincabinets]

Watched it all. I'm curious to know if turbos can be tuned for low-rpm power, like sub-80kph to be similar to the SC. Anyone got word on this?

[NitroDann]

Frankly, the tests are intentionally skewed so that its better entertainment rather than just the turbo car wiping the floor. This is easily proven by simply comparing dyno results, the turbo car wipes the floor with the blower, from the 2000rpm test start the cars are dead even then as soon as 2800rpm comes the turbo absolutely wipes the floor until redline.
If you can think of a speed where the car is above 2800rpm in any gear the turbo car performs better, and below this rpm there is no difference. So basically identical below 20km/h and significantly faster at all other speeds.

They have to do this because otherwise its not very entertaining.

Dann

[StanTheMan]

well if you put an NA car in the equation it would probably do the same or similar times. Most of this is about drivers skill. once you get past a certain power you will just wheel spin & its more about control in the particular set up.

There is no doubt the turbo, once it gets to stretch its legs, would kill both Supercharging & NA.(if they had one with around about the same power.)
Both forced cars would probably have a lot more torque than an NA car & would be more forgiving for less skilled driving as well.

It really comes down to personal preference & perceived entertainment.

I cant recall, did they co a cost per HP comparison? and i think that's where Turbo will always win.

The drivability to me would be the most important issue though. And that's a real hard message to get across on Youtube.

[NitroDann]

There is no doubt the turbo, once it gets to stretch its legs, would kill both Supercharging & NA.

Its not even about stretching its legs. Let me screenshot the dyno graphs for you.



Top left: Horsepower
Top right: Boost
Bottom left: Torque
Bottom right: RPM

Screen guide:

Top left and bottom left, horsepower and torque

Because both the torque and horsepower are scaled the same, across the same rpm, and in the same cars these graphs tell an identical story.
This is the actual output to the tyres. As tuning fork points out, there is an insignificant advantage in horsepower that the supercharged car had on this dyno run until 2800rpm. And I'll quote him," Some kilowatts, barely measureable kilowatts".
It looks to me like <2rwkw. So in other words, if you are doing less that 2800rpm, which in my experience only ever happens in 1st gear if you take off lazily, such as leaving woolworths. In this scenario, if you nail the throttle after a gentle takeoff you will be surpassed by the turbocharged car at around 25km/h, about as fast as a fit bloke can run.

Top right screen, boost pressure

The place Marty is pointing in the screenshot is where the turbo is coming on boost, and as he rightfully says that short ramp up to 9psi is considered lag. You can see that these runs are done from 2000rpm, and this ramp he points at represents the turbochargers response when you try and race it at 2000rpm. They discuss this lag being a cost but as we can see the other line, the one from the 'more responsive' supercharger is actually below the turbo at all times except redline. In other words while the turbo does take 800rpm to get to its full potential when drag raced from 2000rpm, it actually is doing a better job from the very beginning of the run. So while you may call it lag, the real question is what do you call the significantly worse thing that the blower is doing.

Bottom right screen, rpm

This is simply shown to allow us to see proof that the graphs we are looking at are overlaid correctly, that each point on the graph is the same rpm for each car.


So in conclusion, the turbo car has an advantage from all speeds exceeding 25km/h, and gives up <3rwkw below 2800rpm. The tests done in vid 4 are not objective and easy to cheat or mislead, but its an entertainment video, they arent a science channel.

Marty and Moogs job is not to present the most scientifically accurate, unbiased tests its to entertain and get views. The best way to do this is to present any heads up battle as fairly even regardless of the truth and to perpetuate the discussion people are already having online. Regardless of what they test or try they need to give both sides of the internet debate an opportunity to argue with their mates and hype the video. Thats their job, and Im not mad, otherwise I wouldnt have been involved with them

Dann

[ManiacLachy]

I feel like the turbo wasn't tuned as well as it could have been - ~180whp seems very low for a GT2560. I understand what you're saying about MCM making an entertaining video, so they were tuned to be as matched as possible and this was done purposefully, not by any lack of knowledge or skill.

Dann, what would you expect to see if you were tuning it? Is the posted power only because of (artificially) limited boost, or would you expect timing and fuelling to have played a part?

[NitroDann]

I feel like the turbo wasn't tuned as well as it could have been - ~180whp seems very low for a GT2560. I understand what you're saying about MCM making an entertaining video, so they were tuned to be as matched as possible and this was done purposefully, not by any lack of knowledge or skill.

Dann, what would you expect to see if you were tuning it? Is the posted power only because of (artificially) limited boost, or would you expect timing and fuelling to have played a part?

As they say in the video, the turbo would be in the middle of its efficiency zone at around 16psi (they run 10psi to mathc the blowers max boost), for arguments sake this is generally in excess of 260rwhp, which is 50% higher than they tuned theirs to. They didnt do this because it would be impossible to pretend that the cars are even, and as I said they need to do this because they need to generate blokes arguing, pointing each other to the video getting hits and making money. Thats the game they are in, and again, I fully accept this.

For anyone wondering, I have built a car with the smallest turbo to achieve 180whp, or 'tuned for low end' as someone might say and honestly it was annoying to drive, it wedged you in the seat every time you breathed on the throttle at low rpm and took a fair amount of concentration, and of course the delivery wasnt linear at all.

Dann

[mk]

Supercharged is better then nothing
It's in the middle off turbo and na
My na6 is the first supercharged car I've owned
I've had a few turbo cars
The mx5 is very nice to drive supercharged and I like it
It's made a fun car into a car that can go fast

[madjak]

There is a use for both turbos and superchargers. Doesn't have to be one or the other.

The Rotrex system is nice because anyone can buy the kit, bolt it up to your motor with some simple tools and drop it off to get dyno'd. It basically multiples your engine power by 1.5 times. Superchargers are great for driving in technically challenging conditions like tight and windy roads and in wet weather. They don't have the power that a turbo can generate but they deliver nice linear power so you get great drive-ablilty but nothing crazy fast.

A turbo is typically far more complicated to install, however we do have NitroDann who can pretty much provide us with a bolt on system... thanks Dann! The fully tuned and well set up turbo will thrash the pants off an off-the-shelf Rotrex install. As pointed out, untapped the power levels are truely epic for a lightweight mx5 chassis, but with all that power comes control issues, especially in the wet.

I would have preferred to see something more like a Whipple / roots style blower compared to the turbo so that the torque curve is a bit closer. A rotrex is really only suited to a high reving engine like a track car, but then this bolt-on system is far to underpowered for that.

As for the MCM tests... a well setup N/A car would have probably beaten both F/I cars. I know from our club events where the supercharged / turbo / N/A / V8 cars sit. All of the tighter and wet events are won by N/A with the faster tests won by turbos and V8s. But all in all it's very close between everything, mostly because all the top cars are well set up with good grip and good drivers.

[Okibi]

There is a use for both turbos and superchargers. Doesn't have to be one or the other....

[madjak]

wow madness! sounds nice and easy to drive too!

Given the weak point of our cars is the gearboxe, there's not much need for anything more than 350 - 400 whp anyway. Go past that and you may was well go for a mid engine sports sedan build as everything in the car has to change. With the right setup you can take either supercharger or turbo to that level and the car will be super quick with both.

There is a reason though that turbo's and MX5's are so popular. Bang for the buck you get something that is a blast of fun and well beat a lot of expensive cars. I think that same theory applies to any bolt on superchargers too and in fact I think it matches the platform better than a high power turbo and retains that fun MX5ness that it had as stock. It's almost like how Mazda should have released them in the first place.

[Code4]

I'm naturally a contrarian, but if I was going to spend money for more power I would actually look at a different car than my MX5.

Having committed heresy here, there are two reasons I would try a sc.

1) Installation is a lot simpler with less things to go wrong/break/leak.
2) Every man and his dog has a turbo (for the obvious reasons NitroDann has so eloquently explained).

[lightyear]

I have dríven both. Both are fun. I like the turbo for the fact it's cheaper, and more fasterer. Makes cool noises too. But after you get over the big power increase, you are left with a car that can break the speed limit faster. There is nowhere to use a fast car other than the track. So you can have as much fun on the road with a stock motor, full exhaust, intake, light flywheel, LSD and short diff gears. Oh, and old hard rubber.

[trader]

Hope I'm not getting off topic too much but endorse Madjak's comments re the rotrex. I have had a Kraftwerks kit on my 1.6 for over two years and for me its a perfect fit for the car. Hasn't been tracked but for around town you cant beat it! It's running the stock computer so only getting 105 kw. It's a neat looking kit and definitely DIY. I had plenty of other mods already (torsen, re route coolant, large radiator) and have had no heating problems. With the stock computer A/C and idle are like factory. Sounds great and only downside is fuel consumption (10l per 100).
It's because of this kit and what it does to the car that I haven't bought an ND! When I'm convinced I need an ND (which is getting close) I will take the kit off and sell it seperately, leaving no holes in the etc..

[NitroDann]

For 105rwkw a VVT swap makes more sense, IMO.

So many options for making as little power as most blowers and lots come with none of the blower problems, like belt slippage, heat soak, economy etc

[lightyear]

Agree 105 rwkw's is achievable with an NB8B motor, full exhaust, intake and a tune. I had to put the restrictive Oem full intake back on to try and fit into out sub 90rwkw class. Dyno read out of 89.3 rwkw's. 94rwkw with $5 pod filter and silicon elbow. Only had cheap $150 extractors and $300 exhaust. That was Oem ECU, no tune.

Nitrodann turbo kit is probably the best value for money upgrade for most. I was being super tight, and managed to do ok with the SE bits. The old carbon fibre car has an SE turbo on it now to fit into class. For road use or general track use the turbo is the winner. But I can see the appeal of the supercharger. It is the same as fitting a 3.0 naturally aspirated motor. Brendans NA8B has plenty of power to keep you happy,