Can I still ask Jake about his cam?

[pbanders]

Uh, I never did find out how it differed from stock before the thread was closed. Hopefully, this is a reasonable request.

[Dave at Pelican Parts]

I'm guessing that longer exhaust duration is one of its features. In fact, I can also guess that this might help get the heat out of the cylinder head because the exhaust gases aren't trapped in the chamber for as long.

The exhaust on our cylinder heads appears to be the biggest bottleneck to making power, so I would bet that this would be one way to both increase power (and efficiency) and decrease head temps.

--DD

[lapuwali]

Jake may have been avoiding the question by ignoring it, as well. One can hardly blame him, as he's in the business of selling this information along with the parts. Indeed, I'm always surprised he's as open and free with information as he is. I'm never surprised when he clams up about something, though.

From what little has leaked out, however, I think Dave's assessment is completely correct. More exhaust duration seems to be one of the keys to improved efficiency, probably in conjunction with improved exhaust ports. Emissions are almost certainly the reason there's too little exhaust duration in the stock cam. Only goes to show that the 3-way catalytic convertor was a wonderful invention. Emissions can drop by as much as 10x with the addition of one of these, and cam parameters can be much more closely tied to the needs of the engine while retaining (relatively) low emissions numbers.

[pbanders]

Sounds reasonable to me, but I'd like to hear the answer from the guy who designed the cam. If this change can be done without introducing significant overlap, then it sounds good to me.

Again, I think the issue here is the emissions constraints that Porsche/VW was subject to. Cooler cylinder head temps are likely to correspond to cooler cylinder wall temperatures. Cooler combustion chamber surface temperatures result in higher CO and HC emissions. Factor in what Jake mentioned, that the engine had to meet worldwide operation needs, and that many climates are colder and need higher temps, then it might explain why the stock cam was designed the way it was. From my experience, the Bosch and Porsche engineers were extremely clever and did things for a reason.

[Jake Raby]

The cam has different lobe centers, as well as a particular amount of added exhaust duration... It has more lift on the intake than the exhaust but the same duration as stock within just a couple of degrees on the intake.
I have tow different ones, one for L Jet and one for D jet... If you want more info email me- I haven't got time for getting pissed off today.

[Alfred1]

Engine Analyzer can perform iterative or "chain calculations" to calculate specs that produce maximum peak hp, maximum peak torque etc. Page 78 of the EA manual gives the example of optimizing lobe separation and cam timing. Use the cam with these (theoretically) optimized specs as a starting point and test it on the dyno. Make incremental changes to one variable at a time and note if there's an improvement in max hp or torque on the dyno. Keep repeating the process until you've found a good combination. Basically it's lots of trial and error.

[pbanders]

I've found from experience at work, that using simulators (in my case, device simulators) does a good job of predicting behavior IF, and only if, the simulator is sufficiently sophisticated to include all external variables and stimuli, and IF the model used is correct, sufficiently detailed, and appropriate for the situation modeled.

I have no idea of if Engine Analyzer meets all these requirements. I suspect it does a good job, as the charts Alfred has shown before are reasonably close to dyno charts for similar engines.

[Alfred1]

In the near future, I'm hoping to get this software. I emailed them about the price and this is what they said:

"WAVE is a comprehensive industry standard product that is used daily to design and investigate the performance of engines at major automakers around the globe. For an individual, the cost of WAVE is significantly higher than Engine Analyzer Pro.

If your company does not have revenue in the millions per year, the ROI may not be there on your investment into the software; I.e. it will not be affordable.

Now the good news, students under University Grant agreements that use the product for no profit and do not engage in commercial work get the product at no charge at all in most cases."

[Bleyseng]

Boy, I have to agree with Jake. Just because you spout theory and math doesn't mean you are a good mechanic. Being a mechanic requires some mechanic ability, building hot rod custom engines requires lots of mechanic ability. Engineers design stuff that "should work". Mechanics or people with ability to work with their hands build it and get it to run.

In my line of work, I run into Architects who couldn't pound a nail in straight if their life depended on it. Same thing applies to the automotive world.

Geoff