Impressive stuff - top marks for trying something different!
Thoughts about airflow The only intake is at the end of the trumpet. Would holes drilled ( or slots opened) along the sides give more intake area? The downside is it would loose any ram-air effect in the velocity stacks Another idea would be fit a wire birdcage dome on the end of each trumpet to give the socks more intake area.
To Design the velocity stacks i used Auto desk Inventor PRO 2016. Its a really expensive piece of software, but you can get a free licence for students which is how i got mine (I'm currently doing a HND in engineering at college 1 day a week) If your not a student you could get it using bogus information as they didn't check any of the details i put in!
I've had basic training on how to use Inventor, but the version i used was a much older version on the college computers so there were a few differences which made it take longer than it should to draw them. The best feature however is that you can change the material type and get a weight of the finished item.
To print them i used a local spot called Fab Lab They are open to the public on Fridays and Saturdays and have a selection of machines such as CNC routers, laser cutters and 3D printers. There are a few of them around the UK and are mostly used by education and people like us. I sent them an Email, then went down to see a very helpful bloke called Jesus who told me how long it would take (12 hours ish for each stack), what materials are available (i went for ABS) and how much it would cost. The cost is based on the weight of the item being printed which is why the feature that tells you the weight is useful. The total cost for both velocity stacks came to £38.80 and about 4 hours on the computer.
After driving the car twice since fitting them on there is a noticeable difference to the note of the engine, and also places in the fueling that are leaner or richer than they used to be, so i know that they are having an effect on the engine and they haven't gone soft with the heat, let alone melt so that's good news
The rear axle is all back in now and the brakes are bled so i can go for a drive soon
Impressive stuff - top marks for trying something different!
Thoughts about airflow The only intake is at the end of the trumpet. Would holes drilled ( or slots opened) along the sides give more intake area? The downside is it would loose any ram-air effect in the velocity stacks Another idea would be fit a wire birdcage dome on the end of each trumpet to give the socks more intake area.
In theory they should be enough room for air to get in as the diameter of the trumpets is slightly bigger than the throttle plates (1mm extra on the diameter) so any extra air flow would be wasted. Its still got stock valves, springs and the rev limit is set to 7500rpm so i shouldn't run out of air for it!
Something along the line later that might be worth investigating , the radius of the bellmouth . I'm sure there is pages and pages of conflicting views on it but different radius can affect engine power and characteristics .
I'm sure you know that already though !
Great to see modern tech being used to solve problems , great stuff .
Yes , i mean thats if you are going for the full on get every ounce out of it thing . Might be worth investigating to change the running characteristics in the future .
erm, cant seem to find the post which says "ooh look heres my new bike throttle bodies" but a 45mm (x4) will supply 300bhp worth of air, if it helps allay any fears or random suggestions above
They look really cool man =] and I like the fact you designed them yourself, Ive just got hold of a new set of itbs for my mx5, from a toyota ae111. they're bolt on flange both sides (fnar fnar) and should flow plenty for my next revision on the engine And i am searching desperately for a set of trumpets in the uk for them haha.
Its been a while since i last posted on here but i have decided to put her up for sale: HERE
I'm not really bothered if it sells or not, but I have seen something else that i like the look of and i feel like i have gone as far as i can with the hillman and i'd like to try tuning some other engines rather than the little 4 banger ( which still puts a smile on my face every time i drive it! )
Speaking of driving it, I went to some private land the other day and tested out the limiter....
Says it all really - especially after all the work you've put into it.
Also a bit of a shame shame that I've seen the car a couple of times but still don't know how a MX5'd Hunter performs, feel free to call in for a coffee if you're over this way before the car sells
I'm not after any spares but if you're welcome to drop old Hunter junk here rather than take it to the scrapyard
Nothing goes to the scrapyard Nomad! But if I'm over your way in it I'll let you know ☺️
My fixation with turbo's and v8's has got the better of me and I don't really want to fit one to the hillman as it wouldn't really suit it. Need to fund building the garage at my house as well!
