When I picked up the Cosworth MX1 cams for our Long-Term 2008 Evo GSR, the gang there went into detail on the process they use when coming up with new performance cams for an engine. And I have to say, it's extensive.
First, Cosworth buys said engine, disassembles it and starts measuring the valvetrain. They check spring pressures on the seat, valvetrain clearances, masses of the individual compents, you name it. Then they take all of that data and start crunching numbers.
For "drop-in" cams like these MX1s, they're trying to determine how the stock valvetrain behaves and how much additional lift and duration it can safely tolerate. This involves calculating everything from spring stress to valve acceleration to oil film thicknesses.
The goal at this point is to ensure that any new cam they come up with doesn't open the valves too quickly--causing valve float and/or damage--and that the stock springs don't snap under the more extreme loading they're being subjected to. It's a process that is equal parts engineering, experience and sweat.
And they haven't even ground a cam yet. Click the jump to read the rest of the process.
An algorithm stares at all of those calculations and spits out a range of potential cam profiles from Cosworth's database that work within the specified bounds. Engineers then grind some test cams and start the laborious task of engine dyno testing.
Assuming the power produced from a given grind is satisfactory, the test is repeated with a few more cams with the same grind to ensure consistency. Are you getting the sense that these guys take this seriously? There's more.
If all goes well, the grind is promoted to the next stage--durability testing. A high-speed valve control check tests for valve float. Scuff testing at low speed of the cam and follower ensures that the oil film isn't breaking down due. There's fatigue testing done at redline, too. A cam grind that passes all of these tests is approved for production.
All this work done by Cosworth is to ensure everything holds up under the lead foots of gas card-havin' hooligans like us.
Jason Kavanagh, Engineering Editor @ 15,851 miles.
chavis10 says:
06:45 AM, 01/27/09
How much did the cams cost?
texases says:
06:56 AM, 01/27/09
So when do we hear about the results, performance-wise?
allenychung says:
11:12 AM, 01/27/09
Man, that looks awesome.
Jason Kavanagh replied to comment from chavis10
03:02 PM, 01/27/09
chavis10, MSRP is $749
texases--I'm compiling dyno charts and will have more info posted tonight.
allthingshonda says:
05:15 PM, 01/27/09
I think you guys should put a disclaimer to remind readers that these modifications will completely void the manufacturer warranty.
subytrojan says:
07:50 PM, 01/27/09
Not true, allthingshonda. For engine-related issues, the warranty would probably be voided. But according to the Magnusson Moss Warranty Act, one cannot simply say that the warranty for the entire vehicle is null and void.
For example, if the Project Evo GSR's radio starts singin' the blues, its repair or replacement should be covered under warranty--unless one breaks it by turning it up too loud to drown the sound of the intake and exhaust out. =Þ