That's what I plan to compare to.

Even if the 272/264 is doesn't make as much power... it's lets the other 'un-cammed' guys make an educated decision as to whether they want a 272/272 set w/ adj.gears, to a 272/264 set w/o adj. gears

 

it isnt going to make more power...just a longer powerband...just no one has compared them back to back to back on all cam durations..everyone has there own ideas on them and goes with it..our after market support is horrible

 

there is a much deeper deal to this. you are still limited by the stock grind in it's base vs a blank grind. cam timing blah blah blah blah

 

My math might be wrong but those numbers you quoted for overlap will require adjustable cam gears. The LSA won't change between the grinds, even using the stock LSA there would be no overlap difference between a 264/272 and a 272/264. Whoever you quoted would require adjustable gears to achieve those numbers.

 

a wise man once told me

"lawl wtf"

 

Not even sure... I just got that email yesterday.
I'll read though the whole thing and see how he figured it out.

 

there is a fatal flaw in the thinking in said "email"

 

Flaw.. possibly... fatal... no...

 

the flaw comes from a lot of things actually. look at the published numbers regarding every component of the valve train.

 

Using the following published numbers, I did my own calculations....
From that I found the following (based on advertised duration and advertised opening/closing);
264/264 -> OL -> -10*, Total LSA -> 137*
272/272 -> OL -> 8*, Total LSA -> 132*
264/272 -> OL -> 4*, Total LSA -> 132*
272/264 -> OL -> -6*, Total LSA -> 137*

Not quite sure where the guy got his numbers from... but these still seem to show that a 272/264 combination will allow for a maximum intake charge, yet not allow for a large amount of blow though.

 

Your numbers are from HKS DSM cams. The EVO ones that ours were ground from all use 110 centerlines for 264, 272, and 280 grinds.

Using the same centerline, a better flow can be had with less blowthrough via less intake duration.

Your overlap numbers are also using @1mm duration. Overlap should be calculated at advertised duration.

 

lift numbers are incorrect. unless said person was "dave" that sent you these numbers


i guess we failed to mention that the evo had a slightly different "272" grind.

also something else that was discussed. to find true numbers, one needs to know the ratio of the rocker as well

 

People on this site need to stop looking at just advertised numbers. lobes have a profile, inorder to see what a lobe really is you need to look at the duration at .006, .050, .200. Lobes with the same advertised duration can have a suprisingly different duration at .200. I also suggest looking at comp they have a special line of lobes just for the ecotec.

 

orly?

 

fast98.

those are designed for the 2.2. not a direct deal for the lsj


want cam info on all cobalt cams?

google search a simple phrase.

lsj cams

one of the top two will be specs from gm on a pdf file.

 

the cores they have might be for the 2.2 but the lobes are designed for any ecotec. I have that file on gm cam specs also.

 

the hex key in the end of the exhaust cam is the difference. lift and duration is also different.

you can stick them in an lsj and get away with it. if you have a weird desire to crank on the starter for a while to get it started.

 

You're missing the point. I know the cam cores might be for the 2.2 but the lobes you can have ground on any ecotec cam.

 

The profiles we were had ground and are spreaking of previously were profiles based off the HKS Evo line. They have a less aggressive ramp which is desirable on base circle regrinds where shims cannot be used, its a less harsh profile on a stroked lash adjuster, part of the reason why we chose that profile.

The lift rate can be inferred by comparing the advertised numbers to the duration @ 1mm as given by Omega earlier. His numbers were correct, just on a different centerline.

We were simply comparing different combinations of the HKS Evo profiles, one of the few profiles that can be used on our stock cams. There are a very limited number of proven cam profiles that can be reground on our stockers while still maintaining proper lash without shims; the stock lash adjusters can only be stroked an additional 3mm maximum. Lifter shims cannot be used on the LSJ head, limiting available regrind options.

 

Yes, they are DSM numbers... they just gave me a good starting place, as I wasn't going to waste my time in front of a calculator for more than 10 minutes.

The posted overlap numbers are actually using the advertised duration, not the actual.

People on this site also have to read as to whether the parts they list will actually fit the engine they have....

 

how about some dyno numbers????? and Comp has the exhaust core, just no intake core for ours, our vise versa, i wrote it down somewhere.....

 

264/264 -> {[(264+264)/4]-110}*2 = 44 degrees overlap
272/272 -> {[(272+272)/4]-110}*2 = 52 degrees overlap
264/272 -> {[(264+272)/4]-110}*2 = 48 degrees overalp
272/264 -> {[(272+264)/4]-110}*2 = 48 degrees overlap

Theres the correct numbers using advertised duration.

 

Holy crap you guys are super smart its scary. I want cams but I have no idea what to look for and you guys are throwing out big words and numbers and equations.... I need to do way more homework on this

 

Yes... my differential EXPLODED... so I need to get my original trans (synchro problem) fixed. BUT, if I can't find someone that is willing to work on an F35 MU3 Trans... then I think I am going to be stuck buying a new/used trans.

Either way... cams gotta go.

 

*sigh*

Yes... using 110 they are the right ones...

The ones posted before were also the right ones... but not for our engines.
Instead of looking up the EVO numbers, I just looked at the DSM spec sheet sitting on my hard drive.... much simpler and quicker in order to get the point across, considering I have stuff to do at work.