Tuning Home made induction

[Dayjw]

Well I have a mk1 75 and I wanted to make my own air filter, I already have the "Bob" to sit on top of the tb so all I need now is some tubing and a filter.

I can get hold of stainless steel tubes no problem, but what would be the best bore size to use? As i'd like to replicate (as much as possible) the GSR one, which sits under the battery iirc.
Also, which filter would be best? Sponge cone, gauze cone or mushroom?

Before I forget, does anyone have any pictures of the GSR one? Because it looks like their website is down or they're no longer trading...

Cheers

 

[DaveMcT]

A bit of physics double a pipe diameter and you increase its flow potential by 16x.

At full flow capacity one bend is the same as 1m of pipe resistance. But on an intake kit this might be a bit missleading because the pipe is not flowing full capacity.

The HGT has a 65mm dia pipe fed from a filter case mounted at the front LHS (kerb side in uk). The HGT makes 130bhp. So using the 16x formula a 32.5mm pipe would give enough gas restriction to suit less than 10bhp.

So wild guessing suggests a 50mm intake pipe would be ok for a 75 engine but as 65mm is not much more cost just go with the bigger bore. The only issue will beif its too fat to fit. I would use a K&N cone filter. Easy to clean and long lasting.

Somewhere in this lot there will be suitable bends though I would avoid the tight elbows
http://shop.ebay.co.uk/?_from=R40&_...=65mm+silicone+hose&_sacat=See-All-Categories

Also
http://shop.ebay.co.uk/i.html?_nkw=...mm+tube&_osacat=0&_trksid=p3286.c0.m270.l1313

These are the alloy bends
http://shop.ebay.co.uk/i.html?_nkw=...mm+bend&_osacat=0&_trksid=p3286.c0.m270.l1313

This is alloy tube
http://cgi.ebay.co.uk/Aluminium-Tub...Supplies_ET&hash=item415418a46a#ht_2815wt_901

 

[Dayjw]

Thanks WhiteSei
I work with stainless steel tubing and operate and set a mandrel bender, so (as long as no one see's me) the bends are pretty much free

I could quite easily sneak out 57mm bore bends to suit and increase or decrease the ends if needed.
What would be the best way to do this, out to the right and straight under the battery using as shallow bends as possible?

Would this work for the cone http://cgi.ebay.co.uk/3-INCH-New-UN...arts_Vehicles_CarParts_SM&hash=item4aa998cb38

Seems cheaper than K&N and utilizes the top of the cone too, where as a K&N is just a blank bit of plastic.

Cheers

 

[DaveMcT]

Search the members motors and a GSR will turn up, but yes get the filter behind the headlight. That one above looks fine. Dont forget the engine breather will need a branch into the new inlet tube.

The big advantage with the silicone bends is you can fine tune the setup and they wont drum on the bodywork. But try it & see how it goes. Maybe use short silicone couplers so you can twist the bends about while fitting it.

 

[m20b25]

Have a gawk at this:

https://www.fiatforum.com/punto/245618-induction-kit-thread.html

 

[Brin]

i made me own on me 1.2 8v MPI engine mate only cost around £60 if i remember correctly









bought all parts from AP motorstore mate

1x 90 degree reducer - 76mm-60mm
1x 45 degree bend - 76mm
1x 90 degree bend - 76mm
1x universal cone filter -90mm -76mm
1x 1m stainless steel piping - 76mm

best to have a reducer me tubing is 3inch wide let me tell you its great can really tell the difference

 

[dave]

Also, which filter would be best? Sponge cone, gauze cone or mushroom?


Cheers

twin code best. sponge are the worse