Supercharging 1.8 Na which version of megasquirt

[gav2612]

Hi Guys, first time posting on the MX5 section so go easy on me.

I have recently purchased a'97 1.8 uk car as a track day car(couldn't put up with the price of consumables, tires or the thought of an expensive bill if something went boom on my '01 M3 while tracking it) I was massively impressed with the little 5's handling but now need a bit more straight line to keep up with the track tuned saxo's and novas that I was hanging on to through the twisty bits

I am looking to put together a DIY supercharger Kit based on the TR lane M45 mini supercharger kit. I am not looking for massive power out of this, 180 or so flywheel horse power should be enough to keep me happy without breaking the bank

I have done quite a bit of research and have decided that a standalone ecu like megasquirt seems the best way to go for power and reliabilty. I have the chance of a cheap second hand MS1, but just trying to work out if that would be sufficient to run the the car with the charger installed or if I would need ms2 or ms3. Have searched through a few forums, and have found a comparison chart, but doesnt really tell me what I need to know specifically for the mx5

Many thanks for any responses

Gavin

[ady_GTi]

IIRC you can use any version without problems. I think the Ms2+3 allow a greater resolution for fuelling and spark tables plus more outputs/inputs for other functions.

I got a chap to buy the bits and build mine so I just had to wire it up which saved a lot of headaches! The mapping is fairly simple once you get your head round things, plenty of guides around for it.

[Richyvrlimited]

MS1 will be fine, ran mine like that for years with about 220bhp.

If you can though consider upgrading to the MS2 and get full sequential going, it just makes the car a much nicer drive, (idle quality/smoothness and around town pootling).

Don't forget unrated injectors, and get the best you can afford, crap injectors just make you hate life, (I'm looking at you RX7 and Supra injectors).

[snotrag]

You need Diyautotune.com! Get their book on EFI its really good, but then they have everything you could need to do the job and they are familiar with the MX5.

[gav2612]

Thanks guys,
from investigation I thought the standard 1.8 injectors while pushed were ok up to around 200 BHP?

The car is for track use and to and from only, so the smoother round town driving shouldn't be too much of an issue using ms1

Have most of you bought a built MS or done it from scratch? From looking on the diyautotune website wiring a built one into the loom doesn't look too hard but just a little concerned if I was to buy a 2nd hand one built for a different car that I may need to open it up and start changing connections

Thanks again for the help

Gavin

[MX-5 Lazza]

1.8 injectors might be able to make 200bhp (probably a bit less) but they would be working very hard to get there. Ideally you don't want to go above about 80% duty cycle and for a track car which will be full throttle and high revs most of the time, you really need to make sure you never get any fuel starvation due to maxed out injectors so a duty cycle much lower would be much safer.

[Richyvrlimited]

I couldn't get 1.8 injectors anywhere near 200bhp at stock fuel pressures, hell a set of Supra 320's were at 99% DC on my mates car and I'm pretty sure that wasn't at 200bhp either

My dads car is about 170 and has stock 1.8 injectors. That's as far as I'd push it personally.

Use the fuel injector calculator on RCeng.com website to work out the size best suited to you.

[MX-5 Lazza]

Supra 320s on my car made it to 220bhp but that was on a Mk2.5 with its higher fuel pressure.

[vigoro]

The yellow top rx8 injectors on my car seem to be coping OK, and mine must be around 200bhp now.

Easy to fit too as they are a direct swap. I believe they are 420cc injectors.

[gav2612]

Learning quickly here guys. Reverant on MX5 nuts does a basic P&P MS2 which will probably be what I was looking for at a good price.

Anyone know what the std red top RX8 injectors flow at? From what i've read the yellow topped ones are 440cc, but cant find any info on the red. The red ones are cheap as chips if they have a high enough flow rate. Any downsides to running larger injectors before installing the supercharger? Would like to have everything up and running normally aspirated to make sure I know it works before going FI

[Richyvrlimited]

As I said previously, don't cheap out on injectors, it's really not worth it.

RX8 'Red-bodied' injectors are 225cc, so about the same size you have currently.



Either pick up a set of RX8 'Yellow-body' injectors for ~£100 from eBay and have them cleaned and flow-tested (another £20 or so). Or buy a brand new set of EV-14's.

Trust me fiddling with your tune for days on end to get an acceptable idle is not fun, been there, got the T-Shirt. I will guarantee you that Reverant will tell you exactly the same thing if you ask him - Great choice getting an ECU from him btw, amazing bloke/service.

When I changed my cheap RX7 550cc injectors for RX8 440's the difference was gobsmacking. EV-14 are as good again in comparison to the RX8 injectors.

[MX-5 Lazza]

I started with stock injectors at 215bhp which I swapped with Supra 320cc injectors. This made the mid-range better but still not a lot better at the top end only allowing 220bhp. Idle was worse.
I swapped these for 350cc injectors from P5 which gave a little more headroom allowing 225bhp and improved the idle a lot. Not sure what these injectors were.
When I fitted the Adaptronic I fitted 550cc RC injectors. The improvement is massive. Not only in allowing an easy 243bhp but also in a much improved idle and much better tune throughout the full rev range. Economy is also improved and it pulls like a train (a lot of this will of course be due to the Adaptronic being a better solution than the eManage blue running piggy-back that I had before).

[petermac]

The good folks at IL Motorsport recommend these injectors for uprated motors.

http://www.ilmotorsport.de/shop/article_detail.php...

No experience of these injectors myself, but they seem to be on the button when it comes to tuning. I've had parts and good advice from them in the past.

Happy Christmas

Peter.

[gav2612]

Thanks Peter, from the specs they seem to be the same ones used in the Rx8 yellow top

Will get some Rx8 yellow injectors as soon as I get the chance at some decent 2nd hand ones they seem to be the best balance between cost and flow rate.

MX5 Lazza im surprised that your running 243bhp with an m45 I thought they were out of puff at just over the 200bhp mark? What other additions do you have to make that? FMIC? Smaller pulley on he supercharger?

I said I would be happy at 180 or so hp and now Im already wondering what extra I need to make 240!

[gav2612]

Just had a look at your profile and see your running an Mp62, forget my earlier comments. Is there anyone that makes a kit for the Mp62 on the mx5 or all they all home made plates and tensioners?

[Richyvrlimited]

gav2612 said:

Just had a look at your profile and see your running an Mp62, forget my earlier comments. Is there anyone that makes a kit for the Mp62 on the mx5 or all they all home made plates and tensioners?

Moss isthe only supplier now unless you have a MK3/3.5

[MX-5 Lazza]

If I was building a Mk1 track car I'd stick to an M45 and keep it to 180ish bhp. Over that and you need to find a way to cool the charge and you are putting a lot more stress on the drivetrain so the costs will start to mount up which negates the whole idea!
To be fair, 180bhp on an MX5 set up properly for the track makes it a very potent track weapon. You don't really need much more. On the road is a different story, mostly because my MP62 gives me masses of midrange torque which is what I love about it most.

[vigoro]

M45 on my MK1 gave me 175BHP when i first fitted and mapped it, however my map was slightly off at the time, so 180bhp should be possible. The car felt more than quick enough when I took it to donington, and i was able to keep up with most cars on track down the straights (through the corners was a bit harder due to lack of experience/balls!) although i had added an intercooler at that point to try get the intake temps down.

[gav2612]

Thanks guy's. the plan originally was just to run it na as a cheap track day car. So far it's cost me under £1400 for the car, tr lane rollover bar and gaz fixed coilovers so wasn't wanting to go mad with the expense on a supercharger. Around the 180bhp mark and under £3000 total spend would be acceptable and would hang on to most cheaper track day cars ar that. Also all the bits would be removable and changeable on to another car were the worst to happen or sold on.