Yep, the VW Rally Beetles made about 120 bhp from a 1600. The Formula Vee cars were 1300s and they made quite a bit of HP.

 

So if the blokes beetle was making 91 BHP how's he doing it? Cause BHP is just a calculation of torque and rpm if I remember correctly and I can't see how you can get more torque out of an engine with out changing the size of the crank or piston and that would make for a larger cc engine so I'm guessing he's got the BHP up by increasing the rpm limit and hows he done that? Is that what port and polish heads do?

 

Johannes Persson's best 1/4 mile run at BugRun 2008. Stock crank, rods and 40x35mm vales in stock VW cast heads.
Dynoed 195hp at 7700 rpm. IDA carbs.
730 kg car

If you go to http://cal-look.no/lounge/index.php/topic,3257.0.html you will see the whole build in MUCH detail, calculations and all. You might have to sign up to see the pictures.
The build starts on page 2.
The man/company behind the engine can be reached here http://www.jpmotorsport.se/e_default.htm

 

That is ridiculously impressive!

 

Torque is a function of the Brake Mean Effective Pressure i.e how well the engine breathes. This BMEP is rev dependent and a good engine builder will be able to put together the right bits with some work to perform exactly where he wants to achieve max torque. Cylinder head work will be critical here to ensure adequate cylinder filling.

A reasonable but mildly modified engine for road use should be capable of achieving 65bhp/litre (104bhp for 1600cc) and a higher modified road car should achieve 100bhp/litre. These figures are higher than the conventional wisdom imparted for air-cooled motors that to be frank, reflect 40 years old thinking. Current theories on tuning will see much better figures than what is traditionally expected. For example, old tuning wisdom says that the port diameter should be 85% of the valve head diameter but current wisdom says that better cylinder filling is achieved using 65% with a flat bottom to the port to accelerate the gas into the cylinder. How many cylinder heads have you seen in a VW aircooled of that type. CB wedge port heads are of that type. Similarly, a lot of old wisdom heads had little port swirl, modern heads do.

 

Nice one cheers for that link I don't think i will be pushing my motor that hard. But 60 BH per litre (90 BHP) on a 1600 looks like a fun motor

 

GAC (Alan) build Formula VEE 1300cc race engines and can get 100BHP out of one, reliably without large cc b&ps. Head work is important to achieve high flow, inc larger valves and bore exhaust. Carbs, twin venturi (choke) can be jetted to deliver fuel in the correct quantities with sparks delivered accordingly. the attention to the build quality and component match is crucial. All too often an impressive parts list doesn't mean instant high power, whereas careful matching of lesser parts can work wonders.

I'd love a project to get as much out of a 1600 engine and that might be my phase III on the bug.

1641 to infinity and beyond......as they say in the movies.

 

I think i'm going to see what I can get out of my 1699cc engine i don't have big carbs just a pair of dellorto 36 carbs a Engle 110 cam and I need some heads so i think I will get some with bigger valves and send them of to get ported and polished. Will a 1 3/8" exhaust system be ok or should I just go for a 1.5" system ?

 

Your exhaust size will be dependent on what size the exhaust valve/ port will be. Will you run heat exchangers?
Speak to GAC and discuss the requirements as advice on the other bits will stem from what you already have and how the heads will be developed. Also, I would get GAC to source some heads for you, whether they are 041, 043 or 044 castings. The 043 sound like it will be the best bet though.

 

Does anyone else remember Tony Royston's 'Prince or Darkness' running 13-second quarters with a 1600cc engine?