4.7 diff mod vs ECU upgrade

In my quest for better performance I am debating which of the following mods to save up for

I have a 1.8 mk1 eunos which I use for autosolo and sprinting at a very wet track day a coombe on Saturday I managed to finally get Camp right which resulted in me being about 200rpm short of the redline in 4th (about 105 mph) just at brake point before turning over avon rise (it was wet I am a pussy :-))

 

This raised a concern in my head that if I was to do the same in the dry I would need to change up to fifth or hit the limiter before avon rise which would be awkward for my poor brain.

 

two solutions to this came to mind 

  1. change ECU and get a remap and up the rev limit - this would give me a litte more HP plus I could get the rev limit raised; or

  2. change the LSD for a modded LSD with a 4.667 ratio  which would give me better accel at the expense of top end which I don’t need as Coombe is the fastest circuit I will be competing on

 

The costs are about the same for each option

 

thoughts please

Uprated ECU? Only one I’m aware of is the FM (Flying Miata) from the States, expensive but good, you can alter variables by laptop, but you also need the same, plus FM’s software, interface etc. Total package - several thousand squid.

BBR might have one, I haven’t checked lately, but on the original BBR with Turbo they weren’t always dead reliable and needed modification in some cases. And you couldn’t change variables - still unprogrammable. Most ECU’s - as standard have fixed programmes, and you can’t alter them to suit conditions on or off track.
AFAIK no-one markets an uprated ECU other than those mentioned.

Boosting top end? I wouldn’t advise it, an engine is only good so far. Mazda wouldn’t limit it if they didn’t think it was wise to do so, nor would any engine manufacturer. In any case, torque drops away from Horse power near the top end, so if you advance RPM it that will decrease further - IMHO.

Ratio change? - sorry, I can’t comment on that, I’m not a mechanic. As for Castle Coombe - never driven it so can’t comment on that either, sorry again!

this is the programmable ECU I am considering

 

http://motorsport-electronics.co.uk/me221-mx-5-miata-plug-n-play-ecu-na8995.html

 

A mate had one installed in his mk2 and got a handful of extra horses

 

The diff mod has been done by a few hill climbers 

 

You can get your ECU over clocked, raising the rev limit for small money, Skuzzle does them, or certainly use to and many have done them themselves. 

Personally, practice. You are always going to find the need for a change up just before a corner where you need to change down again whatever your rev limit. 

You could try changing into fifth a little earlier and seeing if you have enough torque to carry you through as at the rev limit you are well over the top of the power/cam curve anyway

Eddy

thanks for the responses , gives me something to think about whilst trying to save save some money for mods 

 

I will have a look for the power curve to see what a good shift point would be

 

Eddy do you have any links handy ?

Not sure what you mean by links.  We have a typical 1.8 stage 1 power/torque curve which would help you

Eddy

By links I meant web addresses where the curve had already been posted.  

 

Please could you email/pm me the curve or stick it in this thread ?

 

thanks in advance

 

I will have a look at it and then try some experiments next time I am at Coombe

Motor sport ecu is excellent  good power increase and more drivable pm me if you want more info

A update is probably due on this thread !

 

Due to financial constraints I have done neither of the mods mentioned.

 

I have done the following

 

  1. got some tuition, this made a massive difference, I need some more to help with the brave pills in particular getting to and exceeding the limit at speed , I have the basics mostly down though practice is always the best thing (NickD is correct!)

  2. 14 deg timing mod - seems to make the car pull better

  3. exhaust manifold change to one I got of a fellow competitor for £50 make the breath more easily and sounds better

  4. more experience 

  5. changed the tyres for michelin PS3 (limited to list 1a by regs) these seem better than the kuhmo HS51 particularly in the wet though they are more spendy

 

so the wet squishy bit in the seat ios now the weak link on the car , though the suspension could probably do with a refresh soon …