mx5 inlet/bonnet problems

[Talonmotorsport]

I've been thinking again, sorry bare with me
GBS had a replacement fabricated steel inlet manifold on their stand at Donny last year for the Zetec, it was very simple,reduced the height of the inlet and gave better power at higher RPM. Having looked at the mx5 standard inlet manifold for a while on the bench it has the same problems as the zetec, both try and to compact long runs into a small space that give torque lower in the rev range. Low RPM torque is good for 2nd -3rd gear driving out of a corner but as the Roadster is lighter you could move the power band higher up the rev range. By reducing the runs from the plenum to the head it would make the engine feel a little more revy and get it all under the current offerings of bonnet. So is there a market out there for an mx5 version of the fabricated inlet manifold?

This was posted on locostbuilders, very simple to make but maybe reduces low down torque too much with too short a run? This mates to a cut down zetec plastic manifold with the injector mounts.
https://encrypted-tbn3.gstatic.com/i...L1LxvGiXA8hZzg


This is from a blog which can be found on google and uses GSXR throttle bodies, injector ports have been sealed here but would still run injectors if left standard.


This is from the states, looks very nice all polished up in ali but is very costly

[skov]

Originally Posted by Talonmotorsport

This is from a blog which can be found on google and uses GSXR throttle bodies, injector ports have been sealed here but would still run injectors if left standard.

That's only the GSXR ports that have been sealed. The MX5 ones are still open and useable in that photo (they're right up against the head on what's left of the MX5 manifold)

Originally Posted by Talonmotorsport

This is from the states, looks very nice all polished up in ali but is very costly

If you could do something like this for the 1.6, but relatively cheap and not shiny (not a fan of polishing!) I might be interested.
Now if you need a beta tester...

[Talonmotorsport]

I think there might be the option there to reproduce the mx5 section of that manifold with the injector ports so that the GSXR throttle bodies are a straight bolt on part. Time to look on ebay I think for some bike bits....

[PorkChop]

Just to point out - one reason why you don't see that many BP/BP-ZE engines on ITBs/bike carbs is that the standard inlet (and exhaust) manifolds aren't that bad at all. People have reported much smaller gains than those with ITBs on other engines. The UK based tuners seem to put ITBs at the bottom of the tuning list (after an aftermarket ECU, headwork/small increase in CR and cams).

Having said that, ITBs would be something I would consider doing (my engine build plans seemed to have escalated a fair bit from this time last year ). Phil, I would suggest that any design you also fits MX5s, you would be potentially limiting your market too much if you don't IMO.

[jason 82]

Chopper, I haven't seen u on here in a while ! How is the build going ? Those rack extention were fine after. How are you progressing with your build ?

[PorkChop]

Originally Posted by jason 82

Chopper, I haven't seen u on here in a while ! How is the build going ? Those rack extention were fine after. How are you progressing with your build ?

Were they? Good stuff.

Build's going slow, work and life keep getting in the way!

[danilo]

Complete Newby here
So bear with me
What is the basic problem with the MX5 engine?
Is it simply too tall to happily fit ?
Although I've seen a very neatly done install of one into a Caterham SV.. but requiring significant and careful machinings to allow a shoehorn fit
The old long gone Iron Crossflow was ~18" total height, I believe, which was Great! fittment wise, allowing a much lower engine cover/hood than in the typ Locost design. Which IMO allows a more proportioned/pleasing design.

Are there Any reasonably simply fitted engines beyond an RX7 that are in the ~20" max height ranges ?