Bis power improvement

[1973/126]

 I think you will be able to get the 30 bhp from a standard bis engine with some tweeks. Getting hold of a cc700 cylinder head would be pretty difficult and I guess a bit expensive. It is like trying to get  hold of an Air-cooled Panda head. You still can, but they are hugely expensive. (Has anyone ever seen a Panda with air-cooled engine?)
 If you want to stick to the original engine, and get some more bhp just try to do all the possible mods to it you can...

[dajwid]

Getting a 700 head is very easy

http://allegro.pl/item585431571_glowica_fiat_cinquecento_700_stan_b_d_okazja.html

cost about £20

Again Poland is place for  CINQUECENTO parts

For info got to

http://www.clubcento.co.uk/

If there is anyone who knows, its these guys.

[dajwid]

Or this guy who sells brand new ones:-

http://allegro.pl/item567828417_glowica_fiat_cinquecento_700_oryginal_nowa_100.html

Panda heds are like rocking horse Sh*t but CC heads no problems at all.

Would the 900 CC head fit straight on ?

Try this link for a few more:-

http://allegro.pl/search.php?string=cinquecento&from_showcat=1&category=50838&country=1

[1973/126]

 Can`t believe how cheap those Cinquecento heads are.  Well, if I was a bis owner I would consider one of them...

[Pete126]

The top photo is the CC700 head and below is a photo of my bis head, they look identical, as Mali said if the inlet valves are 1mm bigger, in my opinion this is not where the extra 6bhp comes from, its more likely to be a slightly higher compression ratio.
If you look at the photo of the cc700 engine it looks to be using a waste spark coil or could it be a twin coil pack as the distributor is missing, must be triggered by a TDC sensor and other electronics, as for the carb it uses the same twin choke weber.
Also the exhaust manifold is different cause it runs thru to the back.




Here's what they sound like

http://video.google.com/videoplay?docid=-768540567179422494&hl=en

[tcosy]

Thanks to all contributors thus far. Seems the cc700 head is a viable route, especially as the cost is very reasonable. A few questions
1) Dajwid - did you mean the 900cc head and if so was that 900cc version of the BIS engine or a slip of the finger on the keyboard?
2) Is Allegro a Polish ebay equivalent and if so has anyone any experience of using it? for the money quoted i would probably go for a new head as long as its complete, but obviously i am useless with the polish language so any help greatfully recieved.
3) You can see that the inlet Valve is larger in the CC700 head, I will contact the clubcento to try and establish Valve timing and lift. Assumming the timing is Assymetric as in the 126 BIS engine, and the engine rotation is counterclockwise, this would make the Cam unuseable in a 126 install, so a new Cam/regrind would be needed. I'll ask these guys about the timing pickup too.

Thanks Pete for the Pictures of the two Heads, the waterways appear to have been enlarged and/or the head is skimmed for a higher CR.

Pete are you trying the same experiment as you are unlikey to have a spare cc700 head around otherwise.

[Eklipze3k]

I'm a member on ClubCento, if you draft up your query ('cos I don't really know what you're after  ) I'll ask the techy guys and see what they say.

I will freely admit though, most of them know more about the 1108cc engine than anything else but it's worth a shot

[MaLi]

If you look at the photo of the cc700 engine it looks to be using a waste spark coil or could it be a twin coil pack as the distributor is missing, must be triggered by a TDC sensor and other electronics, as for the carb it uses the same twin choke weber.

Well spotted. CC700 had electronic ignition system similar to the ones used on >1994 aircooled engines - maybe it would be possible to adapt the ignition from one of those to fit your BIS. I've been planning to get that done to my aircooled but my car is still in pieces and still in Poland

Regarding the waterways in both heads - I just remembered that head gasket is the same for both cc700 and BIS so waterway should be at least similar.

EDIT: One more thing worth looking at is exhaust system - I think that, as CC700 had engine in the front, there was much more space to sort out the exhaust properly, so I wouldn't be supprised if the exhaust system would be the biggest contributor to the 5hp increase on CC700.

[Gordan]

lol, so we take the exhaust, and direct it forewards  </4

[MaLi]

 </4

[tcosy]

Eklipze3k, i'll get that information yo you over the weekend, thanks.

I know i'm always asking but  , for reference has anyone got a picture of the Air-Cooled head, (i think there were a number of different revisons), from a similar angle to those provided by Pete126 of the BIS head, so i can do a visual comparison with the BIS combustion chamber size and shape. This is the information i have thus far on the BISvcc700 engine.

BIS
26bhp @ 4500rpm
49NM @ 2000rpm
(126.9bmep)

cc700
31.4bhp @ 5000rpm
52NM @ 3000rpm
(134.6bmep)

so a 6% increase in efficiency (bmep) hence 6% increase in torque yet a 20% increase in power.

Power is a product of rpm and as can be seen the modest torque peak increase is at a 50% increase in rpm (no curve available to compare)
So taken on face value this would indicate that the breathing at higher rpm was improved significantly over the BIS install the compromise being torque generated significantly higher up in the rev range (not a big problem 1 up in a light car, not much fun 4 up!)
So my little brain would thus deduce that we are talking classic tuning route, bigger valves, more lift/duration, free flowing exhaust, better ignition/fueling.

Hopefully i can get the Cam lift/duration from clubcento/polish contributors.

What is a reasonable bhp/torque figure for a road tune AC engine, what cam timing/fueling/exhaust?

Is 35+bhp attainable with Multiport injection, i'd like to think so

Cheers all

[1973/126]

 On the left-Panda head, on the right standard 650cc 126 head...

[Rusty's Uncle]

 [-/ Although I am a bit of an Aircooled nut I have also had a Bis for 3 years so have some roots there & I know from the 126 forum that many Bis owners have been frustrated by the lack of tuning options so I find this relatively new thread / idea very interesting. Out of interest , doing a quick sum , if a 32mm diameter valve is increased to 33mm then that gives a 6.35% in volume on the inlet flow and that is neglecting the valve stem area. Assuming the porting is increased in line then that might account for some of the power increase 

[Pete126]

Check out the link http://www.fiat500sport.com/def.asp?l=ENG&sku=1472D065870 it shows what is available for the air cooled and the power gains. could give an insight of how to up the power on the bis

[1973/126]

  they have got some pretty impressive stuff.