VVT Cam Theory
08-18-2013, 10:21 PM
#1
Staging Lane
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VVT Cam Theory How do most go about comparing a VVT cam to a standard cam?
From searching the forum, maximum advance should be designed into the cam because tuning only allows us to retard the cam... so how does one determine maximum advance?
It seems that a VVT cam's intake and exhaust duration should be 4 to 6 degrees smaller than a traditional cam's if aiming for similar top end power? For example... say you wanted the top end of a 220 intake cam with maximum low end and midrange torque, would you then design the cam on a 214 intake duration with max advance built in?
I have a 5.3 LMG... my current thoughts are something like 214/218 or 214/220 on a 111+? . Then using vvt to retard it to get the top end a bigger cam would give me.
I plan on paying to get a custom cam but would like to get an idea of what's even possible before I start asking an expert to give me actual specs. I'm looking for realistic expectations of what vvt can do if some thought goes into the setup.
From searching the forum, maximum advance should be designed into the cam because tuning only allows us to retard the cam... so how does one determine maximum advance?
It seems that a VVT cam's intake and exhaust duration should be 4 to 6 degrees smaller than a traditional cam's if aiming for similar top end power? For example... say you wanted the top end of a 220 intake cam with maximum low end and midrange torque, would you then design the cam on a 214 intake duration with max advance built in?
I have a 5.3 LMG... my current thoughts are something like 214/218 or 214/220 on a 111+? . Then using vvt to retard it to get the top end a bigger cam would give me.
I plan on paying to get a custom cam but would like to get an idea of what's even possible before I start asking an expert to give me actual specs. I'm looking for realistic expectations of what vvt can do if some thought goes into the setup.
08-19-2013, 01:37 AM
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Still thinking out loud here.... I guess you could look at the IVC of the "big cam" with the top end you want, and then look at the IVC of a "baby cam" that you want, and see if retarding it "x" degrees would get you to the IVC of the big cam?
From reading it doesn't seem like tuners have been retarding cams as much as I thought, and I don't think I have read anything where the full available retard was used. Does that mean we should be looking at smaller cams and then retarding the crap out of them?
Or is it just not feasible to retard the cam past "x" number of degrees and expect any increase in top end?
I know everything I have said to this point is extreme simplification..
From reading it doesn't seem like tuners have been retarding cams as much as I thought, and I don't think I have read anything where the full available retard was used. Does that mean we should be looking at smaller cams and then retarding the crap out of them?
Or is it just not feasible to retard the cam past "x" number of degrees and expect any increase in top end?
I know everything I have said to this point is extreme simplification..
08-19-2013, 04:41 AM
#3
Your best bet is to call the guys at MAST and talk to them. They have spent A LOT of $$ on the design of their cams for VVT and understand the VVT process a lot more than you would expect. They can def give you a good idea of what will work and what will not work. I do not know for a face if it is possible or not but they may be able to custom grind you a cam.
08-19-2013, 10:19 AM
#4
Try a SEARCH for PATRICK G. He designed a custom VVT cam for a member by the s.n. CAM for his L92IIRC. I PM'd Cam about his cam and he Loves it!!!
