CR: Beetle vs Type3

[nicolas]

i have been asking myself this question for a while and i can't come up with a conclusive answer.
i know that berg recommended the use of 88 P&C's instead of 90.5's. it has to do with more heat and the car being heavier (i suspect). but he also said the CR must be set lower. so my question is: how much lower? say i run my engines with a CR of 9 up to 9.5, is this still possible? not a soCal engine, just your average European weather.

 

[chopper476]

there is a british guy who runs a 1776 notch with 9.5 to 1 i think, although this has a beetle style upright fan housing. also from the spec list, it certainly looks streetable. specs are on the funkenblitz website
http://www.funkenblitz.com/andrewburtons.shtml

[Zach Gomulka]

In my experience the type three definitely runs warmer than a type one. I'm not sure if it's because the engine has more weight to move around or the type three cooling isn't as efficient. Probably both. I would set the CR to match the cam/engine like normal, then increase the cooling efficiency.

I really think a big help to the type three would be to put an additional fresh air intake on the left side of the engine compartment, each side feeding one carb. More power and cooler temperatures.

[modnrod]

I had a 1641 in a Type3 squareback in the tropics, Northern Territory of Oz to be exact. It's not 48*C and 96% humidity like it gets too at the top of the Gulf of Thailand (yep, that is hot......), but we're still talking 40*C and 80%.
87s have thinner cylinders by a long way than 88s, and less than stock 85.5s, but I just kept an eye on oil temps and drove accordingly, didn't even have an extra cooler. I also had an Engle100 cam and 8.5:1 comp, and used 2 DCNFs on ported stock 355 heads.

Berg is still right though, it would have had less engine life than a stocker, but this one did 40000km for me, then another 30000km for a mate before it finally cracked.
I rekn in Euro-zone where a really hot day is, what, 30*C, you should be fine. How long will it take you to do 60000km in this car before a rebuild MIGHT be needed?

Berg was a leader in his field, and a very smart cookie, but there are many different ways to arrive at the same destination, and one doesn't exclude the other.

[Speed-Randy]

Berg was a leader in his field, and a very smart cookie, but there are many different waysi to arrive at the same destination, and one doesn't exclude the other.

Exactly what I say all the time! Other than the cookie part

[nicolas]

well i brought him up and you summed it up nicely. how many people do actually get to drive their cars and engines 30 000 kms or 100 000kms like a stock engine is supposed to do. and that is what a Berg engine was about. it is all over in his books. he wants the longevity of a stock engine. so very conservative engines indeed.
So that is not totally what i want. i can live with a rebuild in the next 30000 kms (as long as it is not under 10000 like the last one). hence the question. i can tweak, but how far?

[modnrod]

I'd build the motor the same as any other. If you're really worried, then 0.5 lower CR with the same deck height will make a difference to combustion temps without adversely affecting torque much.
The packaging on a flat motor will have more effect on the design (intake lengths, exhaust, etc) than compression ratio for a street motor.

[hotrodsurplus]

As long as the compression ratio is adequate for the cam timing and chamber design then it will not run much if any hotter in a Type III than in a Type I.

Compression ratio does not translate directly to heat. Power translates directly to heat. But that heat does not always have to go into the heads and pistons. Last I checked guys were building BIG power with BIG typ III engines with lots of compression ratio and not having heating problems.

I ran more than 8:1 with a stock cam in a '65 notchback and drove over Baker Grade and Cajon Pass during the daytime and never had cooling problems. The stock cam reduces the effective CR by about half a point so you can (actually must) run a lot more static compression when you increase cam timing. Case in point, my old coworker at Kymco Motorsports, Ronnie Silva, ran a 2276 with about 9:1 and about a 295* duration cam in his notch. It ran cool as ice and turned a low 14 on rock-hard tires when we went to Bakersfield.

Set the static CR to achieve the right effective CR with your cam. Run a tight deck. Run as small a chamber as possible. Shorten the advance curve to reduce total timing a little bit (tighter deck and smaller chambers reduce the need for a lot of total timing). It will run just fine.

[dirk zeyen]

Like Zach said, bring more fresh air to the Engine. More rpm an more cc needs more air..... and even the fan needs more air if it turns higher....

Greetz: Dirk

[Bruce]

.... Northern Territory of Oz to be exact. It's not 48*C and 96% humidity like it gets too at the top of the Gulf of Thailand (yep, that is hot......), but we're still talking 40*C and 80%.

To an engine, high humidity makes it run very cool. 
Two reasons. 
First, that humid air has a lot more mass to it, so it can absorb way more heat from the cooling fins.
Second, the water molecules going into the combustion chamber absorb heat, just like water injection.

The worst place in the world for cooling an air cooled engine is a place like Phoenix or Las Vegas, where they get temps in the upper 40s with NO humidity.

[hotrodsurplus]

One of your statements is way incorrect. Please allow me to correct it.

From this:

The worst place in the world for cooling an air cooled engine is a place like Phoenix or Las Vegas, where they get temps in the upper 40s with NO humidity.

To this:

The worst place in the world is Las Vegas.

I did 20 years in that glittery outhouse. And yes, it's a whore to cool an engine there, the land of the 72-plate Mesa cooler.