SV: Fwd: Performance Cooling Questions

["Roland Johansson" <scirocco@mail.bip.net>]

For high stressed motors there are a 70 degree Celsius thermostat you can buy from VW Motorsport, cost about 5-10 times the price of a stock thermostat that opens at 87 or similar.

Next thing is the thermoswitch for the radiotor, if you take the two-speed fan switch from a VW transporter you have the possibility to either wire in a two-speed fan or wire in your fan on the low switch, it opens at 84 degrees and closes at 76. These to things should help you run your motor cold. 

If you use your motor "only" for racing/rally you can remove the thermostat completly and use a low temp switch.


> Jonas Karlsson wrote:
> > I don't think that the knock sensor will really hurt performance all that much, mostly because it only retards timing when it knocks.  It might actually help (dunno for sure) by keeping your ignition as far advanced as allowed without knocking.

It also retards timing if a stone is hitting the oil pan etc, all mechanical noices retards the timing. The knock sensor is a microphone and detects all mechanical noices.

When it feels knock it retards timing and after some time it gradually advances back from where it was before, you loose power for some time if it kicks in.


> Yep, I'm in complete agreement with your entire explanation. What I want to do, though, is eliminate as much of this preignition as possible before I go to the knock sensor -which I consider inevitable, anyway.
> 
> Here's a question, though. Is pinging eliminated by a ks? My engine never actually knocks; it just sometimes sounds like a bunch of bb's are rolling around in a bucket when under load... 

Should be detected by a ks.


Okay, and now a second issue: How come the engine is more likely to ping when at partial throttle in high gear? Intuitively I'd figure that it would happen under WOT -that is, when there is the *most* load and heat generated. It doesn't work out that way, though. How come?

You might run the motor leaner at part throttle than on full throttle, knocking can be prevented by a rich mixture or water injektion...


> > Even after you get a KS wired in, you still need to do all of the other things to keep the engine from knocking (reduce cyl head temp, higher octane fuel, well formed combustion chamber for optimal flame propagation, etc.), otherwise you won't see much benefit.
> 
> Yeah, how can I reduce my cylinder head temperature. I've already got a cooler fan switch and thermostat in there. I don't want to superchill the engine, though, and not let the thing warm up. In fact, the engine never seems to leave what I'd describe as an "acceptable" heat range.

Richen the mixture, water injektion, polish combustion chambers so carbon has more problems building up, clean piston tops, polish piston tops.

Roland Johansson, Swedish Viking
Scirocco 1,6l RSi -82
Http://hem.passagen.se/toker



--
To unsubscribe, send "unsubscribe scirocco-l" to majordomo@scirocco.org.
If you experience other problems, email: scirocco-l-probs@scirocco.org