Thanks Feral, I've always wanted to know exactly what caused detonation.
My current race motor use to suffer a bit of pinging at 2500-2800 rpm before I put the fuel injection on and lowered the comp. ratio down to 10:1.
Thanks for the explanation

awesome read feral.
cheers

Cheers Feral. Is that an excerpt from the book you mentioned earlier in this thread?

No it is not a quote! It took me from about 6:30 am tilll about 8:00 am to get it the way I wanted and then I had an edit after that

Its hard to make it brief and keep on the plot. When there are so many variables, its ard to keep it from being a piece of techno_ speak that is not easily understandable. Its a great subject and I am always looking for ways to improve efficiency and performance.

I was going to put some info on ceramic coating of chambers and pistons in there as well as this has an effect on the compression ratio you can run. Ceramic coating reduces heat soak into the chamber and piston. This reduces potential for detonation at high engine speeds. Maybe that will come into another thread.

At least on this site, people are more interested in technical stuff and how to do things. Not the grand standing (mines better or bigger than yours) you get on other sites

Any one doing engineering, if you get to do thermodynamics: do it! This is one of the most useful "real world" sciences there is in my opinion.

It runs......but I haven't raced it yet so I'll let you know if it goes bang.
It is ready now however and new pics will be up shortly after the weekend.

I currently have avgas in the tank
I have a lead on some racefuel now thats supposedly about 102 MO and under $1.50 litre.......will let you know if it comes to pass.

Thanks a million feral !!
My pc's on the blink and i've just read it now on my parents pc. I can't get enough of that tech stuff. Just as a point of interest, I am doing mech engineering at uni and I have passed thermodynamics - the stuff you said really makes sence but would have taken me for ever to think of myself.

So then, the fact that some people run 12+ and others only 10 (as noted by current posts on this thread) i guess is due to cams, squish, heat factors, and numerous smaller factors that tally a reasonable difference.

Do you have any figures for dynamic c/r that would be a good aiming point for 98 ron??

I would love to hear about the ceramic coating as well if you wouldn't mind !! haha!

Have you any experience with cam picking and desktop dyno or similar simulators ??

Daniel

I use 8.5:1 as a maximum dynamic CR and only if the ignition advance is programable.
For a dissy engine 8.2 is about the maximum .

Ceramic coating works. Be careful about the quality of any coating you get done though. Cheaper is not always the same quality. I spend around $400 on each four cylinder engine I get coated, and a further $160 on the exhaust headers inside and out.

Its interesting to see that most V8 supercar teams and top doorslammer and rail drag teams use ceramic insulation on chambers, valves and pistons. Some have been using it for 15 years.

HRT replace the bottom end on thier cars after 5000 race Km's and the pistons mostly show no appreciable wear after this distance.

Cooler engines and lower thermal stress on rings (allowing lower ring tensions) are the biggest benefits to performance and reliability.

Engine Analyser Pro v 3.3 is the only one I have seen worth putting any effort into. It takes account of bearing friction ring type and number and lots more. It takes a while to setup but produces good base data to compare likely effects. It is not going to give hard output nmbers but makes a good comparative tool.

Datoman_1000, It would be great to hear how she goes!! And the fuel info would be a massive help, because if I can run 100+ octane fuel It may save me the expense + hassel of pistons and rings!
Daniel.

Datoman_1000, I've visited your website - top stuff!

I've just run a quick check to see how similar our dynamic c/r's are.
I calculate mine as:
static 14.1:1, 55/85 cam, dynamic 9.15:1
and yours as:
static 12.6:1, 40/76 cam, dynamic 9.09:1

So despite being quite different in setup, they achieve almost exactly the same dynamic c/r.

I can send you what desktop dyno predicts your power & torque figures to be if you would like to see them. (read ferel's last post for his comments on accuracy).

Curious to know what you went for with chamber volume and gasket crush.

I have run the car on a dyno when tuning but not for any real power figures yet. I'd like to hear your guestimate.

I have some more pics of the car complet going up in the next few days too