134 replies to this topic

[Alex_B]

 

Awesome work and well done. Suitably impressed is the Spider!

 

Mate, if you need a holiday, I could put you to work here for a few months.

 

Sounds interesting Chris!  A few months eh? 

Now all you need is a 3d modelled carb to showcase your velocity stack!
In true blue peter style, here's one I made earlier. 

 

That is stylish Alex, verrry nice.  Version 36 is OK but the printer needs a tiny bit of calibration, the throat is 45.6 instead of the 46.4mm I was aiming for but my mate's bro reckons he can dial that in.  Version 37 with more flare and the weak areas beefed up will be along soon...

 

Yep I was quite chuffed with it, adding to my portfolio until June when I am gunna get chucked out into the real world and have to get a job ;) 

Now you just need to get it tested to see if it would actually work! 

[Mini Manannán]

This week it'll be tested Alex

 

Does anyone know the radius of that chamfer on the inlet of a HIF44? (does a 38 have the same chamfer?)  If I could match it it would makes things more exact, as it is it's a carbuncle in the airstream.

[Mini Manannán]

Been busy on night shifts this week   Drew up the original in a super-smooth arc from base to lip and a big, juicy radius on that lip:

 

 

 

 

Had a bit of time and went wild with a 4' deep version:

 

 

 

Then we had the idea of putting the bellmouth on an elbow to reduce the clearance problems.  Half way through that I had the notion of easily interchangeable bellmouths and drew up a clip for putting a split pin through:

 

 

Then attached them to the sides of the elbow:

 

[Alex_B]

Lets bring this back from the dead! 

 

I have had an evening free so I thought I would try this whole velocity stack malarky for myself ;) 

Started with a 2 inch stack, 10 degree opening as is found in Mr Vizards book. 


And it fitted to my model of the Hif44


Also a 4 inch pipe (excuse the lack of render, didn't want to wait for that one!) 


and now the fun stuff ;) decided to flow test the ram pipes, they function as designed! Winning! 


Need to improve my setup on the flow bench to improve on its realism but this does at least show it functioning. 
Next up im gunna print the 2 inch pipe and get it fitted to the mini, see how she performs ;) 

[Mini Manannán]

Superb Alex!  I've had another one printed off but haven't been able to make our paths cross :-/  I'll post it up asap/

[Alex_B]

Superb Alex!  I've had another one printed off but haven't been able to make our paths cross :-/  I'll post it up asap/

Ahh wicked, I want to get the 2 inch one printed but current print time is 6 hours and I'm not currently in the house for that long at a time but over easter I am hoping to get it done.

Also want to try and get my carb through flow analysis, that however will be a major headache and not something I want to try just yet ;)  

[Mini Manannán]

My man prints mine off in an hour or so, whether the quality is the same is another thing...

 

He's also printed off a concept elbow you can click different bellmouths onto.  In theory you come back from the track, take your short bellmouth off and click on a long bellmouth and go pootling round the shops using your increased torque.  As I say, very concept

[Alex_B]

What you want to design is a variable length trumpet that adjusts as the revs change, optimum length at all times!

One of the guys who graduated last year from UOB designed a variable intake system and got it flow tested, worked perfectly but was very very complex and expensive

[Mini Manannán]

I got round to see my man who does the printing for mewhere I picked up the latest bellmouth.  Lots of support material to be nibbled away at.

 

 

 

 

The mk1 and mk2 for comparison:

 

 

The elbow is just for sizing really as the clip system's been superseded already

 

 

 

 

 

It'll fit under the bonnet with a short bellmouth on, but only just.  I'll re-jig it so the bellmouth goes off towards the radiator.

[Alex_B]

Looking good! I'm not sure how the flow rate would be affected by your elbow, provided the ram effect can be maximised then it should work better overall compared to the standard 90 deg elbow and air box.

Got some time at home today to print a 2" stack so will hopefully fit it if the weather gets a bit nicer! 

[Mini Manannán]

Looks the schmizzle Alex   When I get my carb back I'll be trying mine.

[Alex_B]

Race yer! ;) 


I was having a think a minute ago, I wonder how the "grain" of the part affects airflow. I actually think there are some gains to be had, the dimples in a golfball are designed to minimise the drag on the ball by promoting a turbulent boundary layer that reduces friction. If I can include the light ridges in my CAD model I can flow test it and it should indicate any effects. 

[Spider]

Unreal stuff guys,,,, truly impressed here.

 

You'll have to build a flow bench and compare all these designs, back to back.  A flow bench is much easier to make than what you may think,,,,

[Alex_B]

Unreal stuff guys,,,, truly impressed here.

 

You'll have to build a flow bench and compare all these designs, back to back.  A flow bench is much easier to make than what you may think,,,,

Just looked into the surface finish of the CAD model, cant do it as the flow sim wont know what to do with it. 

But a flow bench could be an option, might have to look into it! ;) 

[Mini Manannán]

Unreal stuff guys,,,, truly impressed here.

 

You'll have to build a flow bench and compare all these designs, back to back.  A flow bench is much easier to make than what you may think,,,,

 

I might have to investigate a flow bench as well.  I saw something online that involved a normal vacuum cleaner I think?

 

 

Unreal stuff guys,,,, truly impressed here.

 

You'll have to build a flow bench and compare all these designs, back to back.  A flow bench is much easier to make than what you may think,,,,

Just looked into the surface finish of the CAD model, cant do it as the flow sim wont know what to do with it. 

But a flow bench could be an option, might have to look into it! ;) 

 

 

 

 

Alex, I think mine might be 'grainier' than yours?  I imagine that's something to do with the faster print time on mine?  It'll be Wednesday before I get my carb back.

Edited by Mini Manannán, 30 March 2015 - 09:20 PM.