Finally got round to fitting and having tuned a set of 45mm ITB’s I’ve been saving up for last week!
This is the first set of FAJS 45mm ITB’s fitted to an mx5 so it was a bit of an experiment. The throttle mechanism is a bottom mount set up which needed a bit of fettling to fit properly as the starter motor solenoid is very tight, but I managed to get it working eventually and with a very nice throttle feel too. Excuse the nest of snakes on top in the photo. My custom loom to run VVT needs some extending in order to go underneath the bodies!
BHP wise, power has increased 15bhp from 153 to 168bhp @7000 rpm and torque is flat across the rev range at 140ft/lbs. I’m running 50mm CNC trumpets. Tried 90mm’s and there wasn’t much difference in power or torque except moving max power down the range to 6800rpm.
Soft cut is now at 7400rpm and hard is at 7600rpm. This engine wanted revs and seemed to enjoy being spun up but we’ve pretty much hit the limit of what it can do with a stock bottom end!
Either way very happy for now apart from the fact we’ve had snow, ice or rain non stop so I haven’t had a chance to actually drive the thing! Future plans will be a second head that I will port and polish myself somepoint in the never never and some bigger cams. Eventual aim is to get as near as possible to 200bhp per ton power wise and then call it quits. In the meantime I’m looking forward to enjoying all the dorts! DOOOORT! 
Engine noises in the video link below:
Video - Google Photos
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Nice one. I really wanted to run ITBs on my 1.8 but gave up. It’s a big outlay if you don’t know what you’re doing.
I take my hat off to you.
Enjoy the energy and theatre of it all.
Cheers,
Guy
Cheers! All in all it was probably £1300-ish, which for 15bhp is cr*p compared to going turbo on a bhp per £ analysis, but my plan was always to leave this as an NA car as I use it on B roads in the Yorkshire Dales mainly, so the driving experience was the number 1 priority! It was fairly straight forward to fit from a hardware perspective - the main problems were software based due to the VVT engine in an NA, but it was a relatively simple task. Not really any harder than a suspension swap I’d say.
Will get some onboard video at some point, but so far it sounds awesome! 
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It might be poor £ per bhp but it’s worth it just for the sound. 
Your costs are much lower than I’d been working on. With ECU plus ITB’s it was double that for what I was looking at. Looks like I was going in the wrong direction. 
Looking forward to hearing your videos.
Cheers,
Guy
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Love it! Awesome work, I bet it drives amazingly Also very excited for noise videos
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There’s a video at the bottom of my first post from the Dyno 
Will hopefully get some more when I get out and do some driving once the weather improves!
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Yeah the sound is intoxicating! I already had the ECU to run my VVT swap so you could add another £600 or so onto that for an ME221. I’d say that this setup is probably closest in comparison to a set of Jenveys except for the fact I keep my standard fuel rail, which is nice, and there is much more room for longer trumpets as the manifold adpater is smaller and the bodies are fully individual instead of paired DCOE style like the Jenveys.
I reckon you could probably do the whole kit for roughly 2k including tuning and ECU as long as you don’t mind fitting it yourself. 
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Most interesting.
The folk I was chatting to suggested the ME442 because of the integrated wideband sensor but that cost a bit more than the 221.
I had wanted Jenvey heritage throttle bodies for the visual appearance but their MX-5 manifold doesn’t accept the heritage bodies so I sort of lost interest.
I really struggled getting any kind of instruction on how to do stuff. Everyone in that field expects you to know your onions if you’re going for ITBs so for a novice like me it’s a bit daunting. If ITB’s were just a few quid I would have had a go but generally they’re a chunk of change. I could buy a reasonable NB for the typical cost of a set.
What a newbie like me needs is a comprehensive step-by-step.
I’m hoping Greg Peters (CarPassionChannel on YouTube) fits some to a car on his channel. His work is so easy to follow even I might be able to tackle it!
Cheers,
Guy
