I understand Hemi's way of calculating the change in EOIT. It makes sense to do it that way. But in soundengineers excel file, it gives you that calculation as the new normal.

I just don't understand what the true normal is. He says its the actual valve events, but what does that mean? He also says bigger cams will benefit from using the true normal instead of the new normal as Hemi is using. Can anyone explain this?

 

I'm not using hp tuners and didn't mean to thread jack. I put a new thread on the gmt900 section along with a vid of me starting it. It's called can issues

 

I see what you are talking about. If you use Soundengineer's spreadsheet from the other thread, the calculations come out the same as mine for the shifted normal. I've never seen that spreadsheet before today. I've just been using his spreadsheet that simply gives valve events based upon cam specs. This other one saves all the calculations I've been doing by hand.

I'm not sure what he is talking about with the actual normal either. He's calculating the new shifted normal off of new EVC instead of the difference between new EVC and stock EVC for some reason. I'm not sure what the purpose in it is. I'll have to try it on a bigger cam and see what the results are.

 

I was looking at the numbers all wrong when I changed my tables. Google over on HPT forum said he found best resutls with 18% added to his tables. So I added somewhere around that to my talbes but I'm thinking I went to far. I will try what the spread sheet says and see where that puts me.

My stupid *** windows computer crapped on me. Won't turn on and it has all my files on it. I just bought windows 7 to install on my macbook. So I should have it by the weekend.

 

Yeah 18% is quite a drastic change even for a "large" cam. I have used a method similar to Hemi's for quite some time now. The important thing to remember here is their is no need to make a huge increase. Delaying too much you can actually run the risk of washing out the cylinders and rings at lower engine speeds. Which is why from the factory the engineer's have the fuel being injected against a closed intake valve for good evaporation of the fuel.

So basically in a nutshell you want to delay injection just enough to prevent the short circuiting effect of the fuel which is where it gets blown right out the exhaust valve during the overlap.

 

Kluggs, thanks for your input here. Some guys on the HPT forum think it could be beneficial to time the beginning of the injection for when the EV is ALMOST closed, but still open a little to take advantage of the suction effect of the exhaust leaving the cylinder, pulling the intake charge in. What are your feelings on that? Is that something worth taking the time to compute or is there really no advantage to that?

Personally, I don't see a reason that would help any. My thinking is that it would be better to inject when the EV is completely closed and let the downward piston travel suck the intake charge in. But obviously I don't have any experience with this.

 

Hmm well I think their may be possibly a little bit of over analyzing and over thinking things with it some. I mean I see what they are saying and I know a lot of guys have played with the injection timing A LOT on varying setups to see what works best.

On your setup in particular you could always just play with plugging in some different numbers with the injection timing when you are at the track or even some timed runs in the scanner on the street and see what you get.