mx5cartalk.com

Just picked-up my usual quarterly copy of 'Race' magazine (Issue 17 - Feb-Apr '09) & found a 3 page article on an NA6 CAI! I haven't read the whole article yet, as I'm heading out, but in its conclusion the author, Colin Koops, states: "My MX5 currently has 50% more power than when I first put it on a dyno, & I certainly did not expect it to get anywhere near these sorts of numbers, as it has no turbo or supercharger, no hot cams, no high compression. All it has is a big air box & exhaust, & an adjustable air/ fuel ratio together with a small amount of head work"

Of course, this begs a whole lota questions, so stay tuned...

Btw, their website is: www.racemagazine.com.au

What did he do initially - only put one wheel on the dyno?!
(I wonder if that actually makes a difference).

sounds like a load of bollocks to me.

"...50% more power ...

.... errrmmm .... .....

I'd say his airbox was running the original 1989 filter that had been sucked into the guts... And a rat had crawled into the exhaust and died there.

The original dyno run gave 50rwkw, so with a new intake and exhaust and some head work... 75kw (very achievable...)...

That or it is all bollocks.

Gee all you guys spending money on turbos are just wasting your money

it's a typo, what they meant is 500%

Boags wrote:The original dyno run gave 50rwkw, so with a new intake and exhaust and some head work... 75kw (very achievable...)

Some amusing comments but Boags latter is closest. Author mentions he did much research & was influenced by what appears to be Matty's article, as well as a trying to achieve an airbox volume of ten times the engine displacement, something apparently sought after in Japanese motorbike racing.

Author started with 73bhp & ended up with 110bhp. Along the way he replaced the rear section of exhaust with 2.5" pipe & muffler for an increase from 73 to 76. Next was a larger five litre volume airbox which took him from 76 to 86. Next he attempted to address high airbox temperatures by coating original headers & heatshield & adding an additional heatshield. Next was the head which was faced along with valves, & seats ground. Compression ratio raised from 9.4:1 to 9.8:1 & the interface between the head & manifold modified (pls note I'm using the same words the author has & not interpreting what I think he means). Dyno now showed an increase from 86 to 93. Next was a GReddy E-Manage taking dyno reading from 93 to 98. Next was an even bigger airbox of ten litres volume taking the dyno reading from 98 to 105, however once air/fuel ratio was corrected back to 12.5:1 result was 110bhp @ 6700rpm with a 15 degree difference in temperature between ambient air & airbox air. What isn't mentioned in the article, but is apparent from photos, is that the airbox picks-up cold air like the Jackson Racing CAI from the mouth of the MX5 via the opening in front of the top of the radiator where the bonnet opening mechanism is. Also apparent is that the airbox has been insulated as much as possible.

However author doesn't mention if the same dyno was used each time or anything about conditions. Also not mentioned is if any consumables were replaced along the way which also might have affected dyno readings. Three pages with four photos - worth checking out at the newsagency if you're looking for ideas as there is more detail than mentioned above.

I'll grab a copy for a read (I try to remember to buy this mag anyway), thanks for posting this clubman.