Tuning Advice

[smiller]

Got a 1995 MK 1 UK '5 that is currently standard and unmolested. However (you knew that one was coming) I feel a slight tune-up is in order. I'm thinking - initially - a free-breathing air filter and a rorty 'zorst.

Not fussed on which make of air filter as long as it performs well and is easy to fit. As for the exhaust, something fruity, not too loud, and not obnoxiously wide.

Oh, and after fitting both, will the engine need re-tuning?

Cheers

[MX-5 Lazza]

You can fit a replacement air-filter or even better, a cold-air induction kit if you like, they sound great but don't expect any real performance improvement. You might feel like it's had an effect but it's usually just because it sounds better.

Similar with exhaust. Replace the back-box and you might free up 1bhp if you're lucky. Mid-pipe & sports cat might get you a couple more and a header might get a few more.

So in total you could spend well over £1000 on a full exhaust system & induction to get a 0-15bhp improvement. I've never actually seen any induction/exhaust work make any positive effect on a dyno run (some show a torque loss). It will sound much better though which will make it feel better (give the impression of being revving more freely).

It won't need any retuning - partly because it won't actually affect anything that matters and partly because there is nothing to retune (it's not possible to tune the stock ecu).

Edited by MX-5 Lazza on Monday 9th February 09:40

[smiller]

On that bombshell I may leave it "as is" then!

[juansolo]

Tried both on my MX-5s over the years. Stuck a Racing Beat induction kit on the first with no perceptible benefit to performance, but a huge noise. Great... but massively tiring on the M-Ways. It lasted all of about six months. I also tried a Miltek back box on it with an embarrassingly large tip (that I cut off and replaced with a much more subtle one). That made it sound a little louder, no where near as much difference as the induction. In the end I decided it wasn't worth the £50 a year hike in insurance for it being there so I took that off too and returned the car to stock.

My current car is also now stock again. It had the K&N Typhoon induction on it. Really very good. Sounded like carbs with your foot down and was not very intrusive when you didn't. Quite inoffensive overall. Totally addictive and it lasted 2 years on the car. However there are a couple of downsides, it gave a little flat spot in the power delivery and at around 90 leptons it whistled annoyingly. Again, other than the noise, which was actually very cool, no perceptible performance increase. If anything, going back to the standard induction, it seems to have better throttle response and that flat spot has gone.

So, IMO, if you want it to sound good and accept it's minor issues, the K&N is the way to go. Or just not bother and enjoy it as is.

[MX-5 Lazza]

Extra £50 insurance just for a replacement back box????? Name and shame that insurer!!! That's ridiculous! I'm paying about an extra £100-150 for...
Almost an extra 100bhp & 80lb/ft
Racing Beat Back box
Larini Sport Mid-pipe
Larini Sport Sports cat
MP62 Supercharger
TDR Intercooler
eManage Blue
J&S UltraSafeguard
340cc injectors
FM Twincooler radiator
P5 PD suspension
Elise seats
HD Deuce roll-bars
17" OZ Racing Superturissmo
...and I'm sure there is other stuff I'm missing

Most decent insurers wouldn't charge any extra at all for an exhaust box that offers no performance increase.

[skinny]

but you is old innit

some insurers are just ridiculous on mods tho. flux are quite good tho, as are a-plan

[MX-5 Lazza]

I is old compared to you but you's just a kid

But even still...

With AON, the general rule they used to work to (maybe still do) is to add 25% for performance increases that boost power up to 200bhp and 50% over 200bhp. Non-performance mods would only increase the premium if they increase value i.e. alloy wheels, stereo. Exhaust would add nothing to premium.

[juansolo]

Can't remember who it was with as it was probably about 9 or 10 years ago. But I do remember that I was paying an extra £50 for the induction and exhaust on there despite no perceptible performance benefit. Recent K&N thing cost bugger all extra. But then I am quite old now also.

Edited by juansolo on Tuesday 10th February 21:21

[Dr KT]

Best thing for performance is

a) increase your driving skill (not in a cheeky way!)

b) Tyres, brakes, suspension will return more "gain" than performance mods.

Enjoy.

[MX-5 Lazza]

Having said all that, if I had a standard car I'd certainly fit a replacement back box (dual exit) and an induction kit. I love the noise

[smiller]

Dr KT said:

Best thing for performance is

a) increase your driving skill (not in a cheeky way!)

b) Tyres, brakes, suspension will return more "gain" than performance mods.

Enjoy.

Well a) is a non-starter as Loeb owes me fifty quid at least from previous lessons

As for b) tyres are definitely due a change, as they are all mix 'n match at the moment. Any recommendations? Can't afford major suspension mods, but maybe a strut brace?

Happy enough with the brakes so far.

[GravelBen]

Underbody suspension braces have much more effect than strut braces (if you don't have those already)

[dan1981]

Just on the insurance front.....


I'm with A plan - well i'm actually with someone else but i get it through A plan.

I can do anything i want to the car except supercharge it, add a turbo or add nitros to it and my insurance premium will not change by a penny.

I just have to inform them when i make the change and its covered. No extra cost.

[MX-5 Lazza]

Just to add to what was said before - the best upgrade you can get is driver training. At the last track day at Brands I was passed by a Ma5da race car/driver. My car has about 230bhp compared to the 115bhp of the Ma5da cars. I couldn't get anywhere near him!

[Nocturnal]

MX-5 Lazza said:

I've never actually seen any induction/exhaust work make any positive effect on a dyno run (some show a torque loss). It will sound much better though which will make it feel better (give the impression of being revving more freely).

Here's my dyno graph from an MX5Nutz meet:



That's with 112k miles, in desperate need of a service (at least one plug buggered), in -2 degree temps. It made the highest powered NA 1600 there. Only power mods were 4-2-1 manifold, silenced de-cat, Apex'i exhaust. That's 118.8bhp/105.3lb-ft. All the exhaust bits were bought used (aside from the de-cat pipe), and only owe me £300 in total.


That said, I'd also recommend doing two trackdays for the same money, or one and some decent tyres.

Edited by Nocturnal on Saturday 14th February 11:58

[MX-5 Lazza]

So that pretty much confirms what I said. Stock power was supposed to be 114bhp so a full exhaust change from manifold all the way back has given about an extra 5bhp (assuming it could manage stock power before the mods).

[Nocturnal]

MX-5 Lazza said:

So that pretty much confirms what I said. Stock power was supposed to be 114bhp so a full exhaust change from manifold all the way back has given about an extra 5bhp (assuming it could manage stock power before the mods).

I think assuming an 18yr old car will still make 114bhp is a little optimistic, if not a little naive. The closest powered car to mine that day was a similar spec'd car (though with 4-1 rather than 4-2-1 manifold) which made IIRC around 115bhp. Stock cars were struggling to make 105bhp.

[MX-5 Lazza]

It seems to depend on the dyno and how well the car has been treated. I've seen early 1.6s reach over 110bhp and a 1.8 that barely made 100bhp. Both were well serviced but the 1.6 was "exercised" a bit more regularly.
Oddly, it seems cars that get modded seem to hold onto their power better than cars that are left standard. I'd guess that is because modded cars are generally better looked after and are usually propperly driven (these cars don't like a slow daily drudge, they live longer if they are driven hard).

[Nocturnal]

MX-5 Lazza said:

It seems to depend on the dyno and how well the car has been treated. I've seen early 1.6s reach over 110bhp and a 1.8 that barely made 100bhp. Both were well serviced but the 1.6 was "exercised" a bit more regularly.
Oddly, it seems cars that get modded seem to hold onto their power better than cars that are left standard. I'd guess that is because modded cars are generally better looked after and are usually propperly driven (these cars don't like a slow daily drudge, they live longer if they are driven hard).

True, though I had heard rumours that the dyno in Brough was 'optimistic' from an SX owner. A friends '98 1.8L made 134bhp which was about the closest to stock power any of the 5s got. He was complaining that he'd lost 1bhp!