[engine_work] Mi16 Direct To Head Throttle Bodies!

[Powers 13]

The ones i had were 42mm, with a 6 degree taper.

[Rippthrough 98]

Smooth off that join in the centre otherwise a lot of your hard work will go to waste.

[Sam 4]

Hi. I used to own a set of PTS direct to head throttle bodies. That were used on their 309 gti 16's. If you want any pics let me know.

 

Mail them to me and i'll put them up

 

sam @dcoe.net

[M3Evo 0]

Smooth off that join in the centre otherwise a lot of your hard work will go to waste.

 

Will give them a polish and then buff before assembly to smooth out the change of angle, reckon they're still gonna be a bit better than standard type butterflies where the air is parted by the blunt edge of the butterfly and then needs to change direction very abruptly as it hits the spindle and screws

[Rippthrough 98]

Will give them a polish and then buff before assembly to smooth out the change of angle, reckon they're still gonna be a bit better than standard type butterflies where the air is parted by the blunt edge of the butterfly and then needs to change direction very abruptly as it hits the spindle and screws

 

Should do, although the sharp leading edge won't be fantastic, but I'm not sure how else you could do it.

[M3Evo 0]

The way I see it is that with a normal butterfly and spindle assembly, the air has a pretty tortuous route to follow in geting past, starting with the thickness of the butterfly and moving on to the spindle.

 

With my design, the area of the leading edge of the butterfly is smaller in the first place, the total area of the bore occupied by the open butterfly/spindle is less, and the flow path over it is much smoother

[DJ_ManuR6 0]

What final price do you have in mind??

 

Cheers

[M3Evo 0]

Must admit I've not really gone all that far into it.

 

Will have a talk with the machinist to see how much a set he wants and work from there factoring in for the butterflies.

 

I wanna try to keep the cost below £250 if possible so that people have a viable alternative to those currently available, but as I say, I'll have to cost them up properly

[davev 1]

i have just a little idea about the butterfly u were talking about, but knowing f**k all about the job its proberly complete rubbish.

 

anyways about the join in the centre of the butterfly. i was thinking cant you design it like the wings on a plane, just more pointed. so the air has a nice smooth surface to go over.

 

dave.

[Rippthrough 98]

Problem with that is you could start getting silly amounts of lift at the front of the butterfly when it's partially open, which means it'd overcome the spring at high rev's and stick.

[davev 1]

i wasnt meaning the design of lift, but the general design for a smooth curved butterfly to reduse drag and turbulance.

 

dave.

[Rippthrough 98]

i wasnt meaning the design of lift, but the general design for a smooth curved butterfly to reduse drag and turbulance.

 

dave.

 

 

That's what I mean, even if you do it symetrical, there'll be a window that the body passes through where the airflow attaches and accelerates round the upper surface, and seperates and stall from the lower, having a wing like shape, although aerodynamic, would put that lift in front of the spindle, exerting a force which would possibly try to pull open the butterfly.

[miamistu 1]

A little update - more pictures:

 

 

 

 

http://stuartmcguire.co.uk/205/tbs/tb1.jpg

 

http://stuartmcguire.co.uk/205/tbs/tb3.jpg

 

http://stuartmcguire.co.uk/205/tbs/tb4.jpg

[smckeown 1]

there's a great david vizard article in this months PPC about inlet air flow etc, seems there's a lot to consider in this area

[Rippthrough 98]

A little update - more pictures:

 

 

**Contemplates morgaging house for a CNC machine....**

[DJ_ManuR6 0]

any good news??

 

Cheers

[M3Evo 0]

Some bad news in that I buggered up the first butterfly, destroying about 5 hours work

 

As far as I know, Mr Machinist is pressing on with the body bits. I've figured out a better way of making the butterflies so once I get some daylight I can crack on with them.

 

Artificial light doesn't seem to illuminate things well enough for me to zero in on things properly, hence the cock up yesterday.

[M3Evo 0]

Hooray!

 

Nice little update, THEY FIT!

 

[Jonmurgie 2]

Now that looks fecking superb Your going to have stacks of room in that engine bay!

 

Do you know what the effects of having a much shorter overall inlet system will have on the performance? Also are those the holes of the injectors running along the top of the bodies? If so isn't that a bit close to the combustion chamber for the fuel to atomise fully? If not then where are you going to be mounting the injectors?

[DrSeuss 0]

thats the standard mounting point, but yeah, it bothers me as well. The reason race cars put their injectors at the trumpets is to gain better atomisation. But at least you'll be able to run super long trumpets to make up for any shortcomings in the induction length. Or a turbo :

[M3Evo 0]

The length of the system should be pretty easy to change using either Samco stuff or ali tubing.

 

It is the standard injector position which should make for good cold starting etc. Also, people seem to make good power on the standard manifold so I'm not too worried.

 

If anyone wanted, it'd be pretty easy to add another set of injectors further upstream giving the best of both worlds

[Dream Weaver 2]

I read somewhere that the injector position alters the torque curve, i.e. between low down and high up torque.

 

Injectors nearer the head/valves give low down torque and vice versa, or it may be the other way round

[M3Evo 0]

My guess would be that having the injectors nearer the head would favor low end torque as road engine are likely to spend most of their lives not going all that fast.

 

I've had to take the piccie down for the time being before the internet Nazis find it on monday. Will see if Stu can host it though

[miamistu 1]

Internet bitch to the rescue... Here's that pic:

 

[M3Evo 0]

Cheers dude, and all after 5 pints too?!