how to pick proper valve events - Cam Experts please come in
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how to pick proper valve events - Cam Experts please come in
I've been doing a lot of research to understand cams better. From what I understand, the key to camshaft selection is getting the right valve events for your particular goals and engine combination. My question is, how do you figure out the proper valve events? I've searched both this section and the Advanced Tech section, and have been unable to find the answer. Hopefully the cam gurus can give me some insight.
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Choosing valve events requires considerations such as powertrain configuration and performance goals. Once I understood where I wanted to be in terms of budget, combination and performance/drivability, it was easy to find all the valve event guidance I wanted right here on LS1tech.
You can see my notes in the attached spreadsheet (download and replace the '.doc' extension with '.xls'). For me, it became clear that average duration, overlap, IVC, split and LSA represented useful 'handles' on my valve events. Once you understand your targets in terms of these parameters, you quickly find that you have enough information to derive your VEs.
A wealth of cam information expressed in the terms I mentioned is available on this site. I'd recommend searching for guidance on these 'handles' according to your unique combo and performance targets.
You can see my notes in the attached spreadsheet (download and replace the '.doc' extension with '.xls'). For me, it became clear that average duration, overlap, IVC, split and LSA represented useful 'handles' on my valve events. Once you understand your targets in terms of these parameters, you quickly find that you have enough information to derive your VEs.
A wealth of cam information expressed in the terms I mentioned is available on this site. I'd recommend searching for guidance on these 'handles' according to your unique combo and performance targets.
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Choosing valve events requires considerations such as powertrain configuration and performance goals. Once I understood where I wanted to be in terms of budget, combination and performance/drivability, it was easy to find all the valve event guidance I wanted right here on LS1tech.
You can see my notes in the attached spreadsheet (download and replace the '.doc' extension with '.xls'). For me, it became clear that average duration, overlap, IVC, split and LSA represented useful 'handles' on my valve events. Once you understand your targets in terms of these parameters, you quickly find that you have enough information to derive your VEs.
A wealth of cam information expressed in the terms I mentioned is available on this site. I'd recommend searching for guidance on these 'handles' according to your unique combo and performance targets.
You can see my notes in the attached spreadsheet (download and replace the '.doc' extension with '.xls'). For me, it became clear that average duration, overlap, IVC, split and LSA represented useful 'handles' on my valve events. Once you understand your targets in terms of these parameters, you quickly find that you have enough information to derive your VEs.
A wealth of cam information expressed in the terms I mentioned is available on this site. I'd recommend searching for guidance on these 'handles' according to your unique combo and performance targets.
224/224 114lsa
IVO - 2 ATDC
IVC - 46 ABDC
EVO - 46 BBDC
EVC - 2 BTDC
Exhaust Centerline - 114
Overlap - -4 degrees
224/224 114+4
IVO - 2 BTDC
IVC - 42 ABDC
EVO - 50 BBDC
EVC - 6 BTDC
Exhaust Centerline - 118
Overlap - -4 degrees
The 224/224 114+4 should behave like a 224/224 110lsa on the intake side because of the advance, but having the same overlap as the 114lsa cam, thus idling better than a 110lsa cam. It would also have a broader power band than a 110lsa cam, correct? What I'm trying to understand is the effect this will have on the engine's power output. How does closing the intake valve sooner affect output? Or opening the exhaust valve later, etc.?
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For example, let's say a car makes 370rwhp @ 6400 RPM with the 114lsa cam. Will the 114+4 cam make more power? Or will it still make 370rwhp, but at 6000 RPM instead? These numbers are purely hypothetical.
I apologize if some of these questions seem basic or "common knowledge." I just haven't seen an explanation of how to narrow down the valve events needed to reach your goals.
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It's prolly best to sidestep the chicken or egg conversation. I would agree that valve events are indeed what we're selecting when specifying a cam. I would, however, suggest considering how the VEs are related. The relationships between VEs are captured in the handles I mentioned. How IVC has been found (through expensive empirical testing) to consistently place the torque curve is documented in this forum. Now split your duration depending on the relative breathing ability of your intake/exhaust, *approximately* center your EVC and IVO events around TDC and you'll be moving toward a unique solution for VEs. Of course, this is just my opinion. You'd likely get the best results by talking this out with a sponsor.