Supercharged Blackjack Avion

[QFAD]

Hi Andrew,

I have just re-read this post and I have really enjoyed your 'blower' journey - fingers crossed for your next test drive.

PS your to be congratulated on your engineering....

[andrewc]

Its been a long time since I updated this thread, but accompanying my Dad as his passenger on the 10,000ft run last weekend has got me motivated again.

After the last post quite a few things happened:

I drove the car quite a few times and still experienced massive pinking under boost, although when the boost did come in acceleration was very lively.

I remounted the carb and moved it inboard quite a way to allow me to use a stainless tube between the carb and supercharger with the silicone hose now just bridging the small gaps at either end. This is a much better arrangement.

On one test drive I experienced a thrown drivebelt, which had been proceeded by quite a lot of belt slip and after much headscratching now have a much improved threadpath that puts the idler pulley in the "slack tension" side between the crank pulley and supercharger (where it always should have been in the first place). This improved but didn't cure the belt slip, and the car still pinked, no matter what I did to the timing. Plus I did have a fairly large backfire, but it doesn't appear to have done any harm.

After this demotivating experience luckily summer holidays and related family activities intervened and the car languished in the garage for a few months. But now re-motivated after the aforementioned 10,000ft run I unearthed the car this morning. Another short-test drive confirmed I still had belt slip and pinking, despite going to a grade colder/harder plugs.

This has lead me to decide to change from a vee belt drive to a 4 groove polyvee/serpentine type belt. When I started the project, I said in the first post that I had calculated I needed a pulley of around 70mm to give me 6psi boost, which is generally regarded as a "safe" level for supercharging road engines from a starting compression of around 8.5:1 according to a number of sources. However, the Aisin supercharger conversion pulley that arrived from the Australia was 60mm which in theory probably gives upwards of 9psi. What I also calculated is that this raised the compression ratio to around 10.9:1 - which obviously doesn't help the pinking - 6 or 7psi boost will keep the compression down to around 10:1. I've always suspected that 9psi was too much boost and probably too high a compression ratio for safey.

Now the supercharger arrived with a 4 groove polyvee pulley of around 67mm dia., but as the crank and alternator were conventional vee pulleys, I swapped the charger to the 60mm dia. vee pulley from Australia for simplicity and ignored my calculation based misgivings (because I'm a berk)

What I'm going to do now is refit the original 4 groove pulley, and I've just found a suitable 92mm dia. crank 4 groove pulley on Ebay, which gives a calculated boost of 7psi, plus a suitable dia. polyvee alternator pulley. As the original supercharger came with a polyvee, this should cure the slippage issues, and the lower boost / compression ratio should help a lot with the pinking.

Now I just need to find a creative way of joining the 92mm dia. polyvee to the crank. What I'm thinking of doing is machining some kind of reference/locating feature onto an original 2CV or Blackjack crank pulley, and a matching "female" feature on the new 92mm polyvee crank pulley (there is plenty of "meat" in its centre) and then I'll bolt the two together - simples. If anyone has an old crank pulley they don't want I'd be interested by the way - I have a feeling this may take more than one attempt to get right.

The only other thing I need now is to find that cheap lathe I've kept meaning to buy - it would have come in handy so many times on this project and the lack of the facility to machine pulleys etc. is the main reason I didn't do what I'm doing now in the first place

The saga continues but the Avion will be back on the road soon (hopefully)

[howardjs]

http://www.ebay.co.uk/itm/Centre-Lathe- ... 3d03dfd6f2

Hi Andrew, nice to talk to you again at the 10,000ft... Re lathe, This one is cheap enough (at the mo)!

[andrewc]

Hello Howard,

Thanks for the tip, but 4 1/2" centre height and 24" between centres weighing around 1/4 tonne is a bit big for my garage.

I've just won a Myford ML10, which is 3 1/4" centre height, 18" between centres and around 50kg's so a bit more my size - I'll just have to take lots of little cuts rather than ploughing material off.

If I ever need more centre height I'll have to ask if this chap sells castings for his spindle raiser - ingenious!!

https://www.youtube.com/watch?v=2ivuCRavE8I

[howardjs]

OMG...not sure about the tool post made up of angle plate, vee blocks and clamps... scary

Pity you are so far away or you are welcome to come down and use my M300 anytime...

[andrewc]

I've just realised its nearly 12 months since I first posted in this thread - I need to get a move on

The Ebay Myford lathe arrived by courier yesterday evening.

Its now installed/wired up and I've faced to length the alternator polyvee pulley and faced off the front flange of the vee on the crank pulley. I'm now ready to offer up the new crank polyvee and work out what I need to do to join the old and new pulleys together.

And tomorrow I will be replacing curtain poles in the living room in return for being allowed to spend most of today in the garage - life is a two way street!

[SILLYCVS]

Despite whay people may think, forced induction isnt a just bolt in on job, seen film, read book got T shirt as they say.

[andrewc]

True enough - I did read many books before I started, but its certainly not a bolt on mod.

However, if anyone has a go doing this to a 2cv with an Aisin AMR300 in the future at least there is a record of some of the things NOT to do - I've made the cockup's so no-one else has to!!!

I now have a polyvee crank pulley made from the remains of the old pulley and the new crank polyvee pulley mated together - I should have bought a lathe before I started this and it would have had a polyvee belt drive rather than a vee belt drive from day 1 (please refer to above comment about cockups)

[SILLYCVS]

Keep up good work, once sorted they are a real crack to drive and startle a few faster cars

[notsmartcar]

If you look on the 2cv forums you can buy a ignition system around £160 ish that you alter to suit your requirements with a lap top,that is proving to be very popular and giving good results by all accounts