Stijn - a race car builder will have cam profiles ground to their spec.

I'm surprised no one mentioned the Honda S-2000 - that's a high rpm motor.

Ford developed the GT-40 F- killer by running a bunch of engines until things broke - beefing that up and then running it some more, then beef up that part. Over & over again. R&T or someone had an article about how they unfairly stuck it to Ferr&*&i by dong things that way.

More recent R&T articles have focused on how to get rid of the valve train (solenoids, etc.) which is a major problem in getting high revs - as well as being a very crude way to control mix inputs to teh comnbustion chamber.

that i understand, but with our little engines, are there much folks that actually go far above 8K revvs? even with custom cams?

Most GT class PCA racers do go to about 8000 RPM as did the factory racers. To do this generally means adding Ti retainers and heavier valve springs. Although I got some 935 heads with stock retainers and stock springs. They may not have been original type springs though. The bottom end of a 911 up untill the 3.2l cars is usually fine until 8000 rpm. Many people add rod bolts and or aftermarket rods for an extra margin of safety. This way if you miss a shift the bottom end usually stays together. The valves just float and get bent.

Your stock 3.0 or smaller engine can all hold together till the 7200 rpm "S" redline and will probbaly hold together to 8000 rpm. The redline on these motors is based on the cam profile. There is no point reving these motors passed the stock redline because they "run out of cam". There is no HP above the redline.

I have heard of a few guys running to 9000 rpm. This always involves Ti valves at about $120 a pop. One of Elgin's (a cam grinder) customers did it, he had to change valve springs every season. The key to high RPMS is a light valvetrain. It is easier to change the direction of a lighter valve. Most of today's high revving engines use 4 valves per head. That means for a given application each valve is smaller. You will notice the latest RSR is pushing past the 8000 rpm limit a little.

I suspect that the factory went through the following process for setting the red-line.

1) Chose the rev range for the engine. For a given capacity, a higher rev range will result in more HP.

2) Select the appropriate bore and stroke to keep the piston acceleration within a reasonable rate at peak rev's. If possible use existing pieces to save tooling costs. At the same time design the bearings to ensure adequate bearing surface area without making them so large as to induce excess drag.

3) Select the appropriate cam profile, CR, chamber design and induction system to provide as much as possible the ideal air flow and combustion charactoristics. Doing this may result in step 2 being modified or possibly multiple configurations might be reviewed in parallel. Based on the cam's valve acceleration, valve train weight, etc springs will be chosen which keep the valves from floating but are not so stiff that they cause additional drag or long term wear issues.

4) Build and test the prototypes and try to identify issues. In some cases portion of the engine may be tested as a single cylinder engine. This may result in some changes or updates to the oil gallaries in the crank or case to address oiling issues. Wear issues in various sub-assemblies or pollution issues may result in the design also being tweaked.

Of course, in a company the size of Porsche, they will always being trying to use as many existing pieces or concepts as possible to minimize the tooling investments. My favorite example of this is the continous spectrum of development from 571 - 911 - 906 - 908 - 917 engines.

When it is all said and done, you will have an engine which is designed for a certain rev range (and red line) from top to bottom. Increasing the peak rev's will start to push different sub-systems beyone their ideal range of operation. The order that this happens will be different for each engine, but you can get a sense of it by what Porsche changed from engine to engine.

Funny ... 40 years later they do it the exact same way - ahh progress. :rolleyes:

Some CAE simulation was done as well, but only at the component level (usually after the part breaks the 1st/2nd time).

You haven't seen/heard anything like a V8 pushrod engine seeing 11,000 RPM and living to tell about it :eek:

Ford did CAE in the 1960's? Considering the state of the art in computers back then, that must have been some effort. I used finite element models for heat exchange modelling in the late 1970s and- was the first person in my field to do so. The comp. ctr. got mad and tried to find out who was choking up the Amdahl.... This was all in FartRAN and I had to write it all myself. A real PITA (of course if it was easy somebody else woulda beat me to it).

Only a huge company could afford the expense in the 60's - and off the shelf numeric analysis progarams were not available until the 1980s so they would have to have paid programmers also. Its all over the place now - I'll bet people will buy it from Toys R Us soon to give the kids something to play with...

I read it twice and come up withy this conclusion, he was refering to the way they drove it til it broke then made it stronger, just like 40 years ago. his post indicated that on the new model they did some CAE also, but made no indication that they did CAE 40 years ago. Is my impression correct?

Hmmm. well what we call CAE today (which uses finite element analysis, where a grid of points covers the thing and you define certain sinks and sources, flows, into and out of each point with a set of equations for each) might not have been what they called it long ago (as in the 1960's).