MX-5 Project log thread

Couple of small updates.

Firstly, Saturday's dyno result.

dyno-supercharged.jpg


Very happy with this! I was expecting between 150 and 160bhp, so 164 is a figure I'm very happy with. Probably nothing to people with 2, maybe 300bhp at least, but it's nice smooth power, and headline figures aren't what MX5s are all about. The increased power really exploits the chassis and its amazing ability. The handling makes me smile every time I chuck it round some bends, and the supercharger whine makes me smile every time I bury my right foot. But I digress..

Next steps for power in the future? Well it'd be lovely to have something extra ready for RR11 ;) Proper management would be the first thing. Well, after I've uprated the clutch and diff to handle the power. Then the next logical steps would be an intercooler and smaller 'charger pulley for more boost. But we'll see what the future holds. I love it as it is right now to be honest, and I'm wondering whether the high cost involved in buying and properly tuning a piggyback/standalone management system is worth it to gain a few BHP and a couple of MPG. But then again I can't imagine ever selling the little red beast.. Oh well. Time will tell!

Here's a video of the car on the rolling road, thanks to mr ScoobyDoo69.

 
The next small modification I've done has been the air intake. The standard Jackson Racing one provided with the superchargers does the job, but it's quite restrictive and inefficient. It also sits right above the exhaust manifold, and I'm sure I don't need to explain why that's a bad thing :)

So I purchased a "relocation kit" which consists of a metal bracket, a small length of 90deg silicone hose and a K&N cone filter. The K&N filters are actually very good, just tainted by the stigma of chavs buying them and strapping them to the inlet on their Corsa.

So, on to the pics..

This is what the Jackson Racing filter setup looks like
step1.jpg


This is what the filter is comprised of
step2.jpg


Filter removed, adaptor plate/bracket attached
step3.jpg


Yup, fits!
step4.jpg


Stupid ballast resistor for the dim/dip headlights got in the way
step5.jpg


.. So I cable-tied it out of the way ;)
step6.jpg


And here we are. All fitted!

step7.jpg


step8.jpg



There's no change in noise, and not really any that I can notice in terms of power, but the main thing should be reduced heat-soak and intake temps when it's hot under the bonnet, especially if we ever have a summer ;) The airflow is much better by the headlamps than it is right down where it was nestled before!
 
Am I reading that dyno print out correctly? 113 wheel hp?

113 wheel hp equates to about 140 crank hp (using the formula for rear wheel drive cars: hp = (whp + 10)/88). Stock 1.8 NBs usually make 109-114whp on a RR apparently, and they are listed at 142bhp, so the formula is pretty reliable.

Obviously, don’t take my word for that, I’m just some bod on the ‘net. But you could do worse than to search for stock 1.8 NB whp figures, and read an excellent article on RRs here: http://www.pumaracing.co.uk/POWER3.htm

Excellent posts by the way, plenty of good photos too which is a major plus.
 
TuckerUK,

Powerstation rolling road has 2 contact points per tyre, and therefore gives a different WHP figure to what you'd expect. What their graph should really say, is power at the wheels, on the two contact points of the dyno. So naturally it has less than the conventional ATWhp figures.
 
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Oh OK, thanks for that ScoobyDoo69, I'll look into that.

Howard, yes I know your car is an NA, I have read the entire thread, I could have picked any model, indeed any RWD car to demonstrate the accuracy of the formula. I was merely using a NB as an example because it's wheel hp was so close to the figure given (unlike the lower powered stock 1.8 NA). Not sure why you posted two more dyno graphs, but thanks anyway.

"LOL not this again"

I imagine it won't the the last time hurddurf, not by a very long shot. Be worried when people aren't concerned with the accuracy of data.
 
TuckerUK said:
Not sure why you posted two more dyno graphs, but thanks anyway.
Click to expand...

Because they're both standard 1.8s, thus backing up people's arguments about this particular rolling road. The NA 1.8 has 130bhp vs the ~140 of the NB so not a lot different in terms of WHP and oh look, they're making 130bhp at the fly, -+ a couple (the second one (M169UMO.pdf) is slightly modified, though) ;)
 
OK, had a quick read, couple of phone chats, and I can't say I'm overly enamoured with a system that can't accurately read the very thing it's measuring, wheel hp. But then I'm 'old skool', I guess if one only works in crank hp the PS system might be just the ticket.

Vive la différence.

Well they do say you learn something every day, and I certainly have.
 
I haven't done much lately, but I thought I'd bump this anyway, in case anyone else cares :D

I've got a few things I'd like to do, but it's finding the time and more importantly, money :(

Namely:

Exhaust - more nice noise :cool:
Roll bars
Stronger rear diff (from a 1.8) that isn't likely to explode
Better, more supportive seats
More power - which involves a smaller 'charger pulley, proper engine management to deal with the extra fuelling, probably bigger injectors, probably an intercooler. However this will probably only yield maybe another 20bhp, so I'm wondering if the expense involved is worth the effort. The extra power over stock is great, and really gets the most out of the chassis. I think any more would just be unnecessary on Britain's B roads with the type of driving I do. Now that I've spent the money on 50% more power over stock, saving the money as opposed to spending a lot more on another 5% seems more prudent.

I'm more interested in handling I think.. Hopefully in the next few weeks my suspension (the dampers) should FINALLY be being replaced to cure the clonking issue that I've long since gotten used to :D And then I'm going to investigate, probably with the help of the suspension designer, how I can 'tweak' the car and chassis to further hone the handling and make it even more precise and controllable. I don't know to what extent the possibilities of this reach, but I'd like to find out! Perhaps a 'refresh' of the components including fresh poly bushes.

Other than that I think I'll just enjoy driving it, and I will aim to do some track days perhaps next year, with one or two CarLimits days thrown in.

Oh and I have a new uprated alloy radiator to fit at some point, and I will probably replace all the hoses with nice fresh silicone ones at the time, but even throughout the hot summer days we had, the current (probably ancient) cooling system didn't really throw up any protest like I thought it would. I'll probably invest in one of these as well, which helps direct the air into the radiator as opposed to up through the top of the slam panel and into nowhere. I dare say if I take it on track, the weaknesses in the cooling system will become more apparent.

Still, all things to think about..!


Happy to answer any questions or criticisms anyone has :)
 
Howard said:
However this will probably only yield maybe another 20bhp, so I'm wondering if the expense involved is worth the effort.
Click to expand...

More power would need a decent 1.8 Clutch and Flywheel (if you want to do it properly) although a used DIY Squirt (i.e. built) is about £200 and will allow you more headroom in the future and better MPG now.

For the extra 20hp it will cost you another £1k (Torsen, Clutch, Flywheel, MS, IC, Injectors) but it will be stronger stuff and capable of more power should you want to move to a tubby.

On the other side of the coin, i would get a MS and injectors now (550 will give you headroom, but 1.8 tan tops will be more than enough) and replace the bits above as and when needed.
 
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