340 dyno chart thoughts

frosty_the_punk said
omg for heaven's sake!

Look at this website and scroll down to the part where it says
"Cam timing @ 0.050 tappet lift"
Hughes Engines

Now go to this website and look at where it says "Valve Timing @ 0.006 Lift"
20-224-4 - Xtreme Energy™ Hydraulic Flat Tappet Camshafts

Do you realise that duration @ 0.006 is ALWAYS going to be a higher duration figure than the same camshaft measured @ 0.050". You DO know that they're different right? why are you trying to compare two cams but using different methods to measure them? Seems pretty silly right?

Congratulations, you're measuring a big cam with a big ruler (duration @ 0.050") and coming up with a numerical measurement for the result.

Then you're comparing it to a much smaller cam, but instead of using the same ruler, you're making the ruler smaller as well (Duration @ 0.006") and then getting the same/similar numerical measurement as a result.

Seriously, If you MUST compare this solid cam to this hydraulic cam, Use the same type of measurement for both. go to a cam calculator website and type in the comp cam's 0.050" specs for 230/236 duration, along with the 110 lobe separation and the 4 degrees of advance. See if you still think that the IVC is 63 ABDC.

Even still, the lash will make the solid cam have less duration @ the valve than it has at the lobe due to lash. So like i keep saying the entire comparison is pointless.

Newsflash, you will NEVER see a solid cam advertised as seat duration. or @ 0.006". The closest thing you are going to get is probably going to be duration @ 0.020" lobe lift. Makes it pretty freaking hard to compare a hydraulic to a solid doesn't it?

And yes, earlier I did state "ATDC" for the IVC when I should have written ABDC. You knew that's what we were both talking about since there is no such thing as an IVC ATDC. Sincere apoligies there.

This was fun, No hard feelings. Let's do it again some time.

Ugh. I really had hoped you would have read my posts. Do you remember when I said I was comparing them using the same measurement? That I calculated the hughes cam at .006 lift? Wasn't that your whole problem with how I was measuring it? Now you're saying your problem is that I'm measuring them differently (I'm not)? So which is it? I was taking them both at .006 (as close to seat as possible) is wrong? Or that measuring them differently is wrong? I am measuring them the same, at the seat. Why? Because that's the measurement you use for calculating DCR. Another important component in building an engine. So yes. I'm using the same type of measurement for both. And yes the XE274H has an intake closing of 63 at .006. Which once again, I use because it's as close to seat as possible. And yes, I mentioned the valve lash. Which you must have missed as well. And once again, in this instance, I don't care about advertised duration. You need to stop beating that horse. Look at the actual events. Like I do. The comparison is not pointless. You should be able to compare any cam with any other cam. It might be hard if you use advertised duration, which you seem to be stuck on. But I can calculate actual (not advertised) events based on the cam card. Just because you can't figure out a cam's seat duration (and other events), doesn't mean others can't. Solid, hydraulic, roller, flat tappet. I mean, if you can't compare different cams, how can you tell someone the gains they will see in a switch?

But. I guess since you are saying I should measure them the same (which I did from the start) that means you're admitting I'm right?

Finally!

This is honestly my last hijack of this thread. I apologize everyone. Frosty I would love to do it again sometime. It is my goal to educate every last person I can about engines and how they work, including you.