Time to go Stage II!

[Alky V6]

Your using these terms to loosly. Compression ratio never changes, dynamic or static. Dynamic cylinder pressure changes with a given boost pressure and compression ratio. I made a simple spreedsheet a while back comparing cylinder pressure at different boost levels. The equivelant cylinder pressure at 35# boost on a 9:1 engine would be a 30.5:1 engine normally asperated. These numbers can be decieving since there is no charge cooling effect on a 30.5:1 compression engine vs. a 9:1 engine at 35# boost.
Comp. Boost Pressure
9 40 477.6
9 35 432.6
9 30 387.6
9 20 297.6
9 15 252.6
8 35 382.9
8 30 342.9
8 20 262.9
8 15 222.9
30.5 0 433.65
Allan G.

Some things that do change the dynamic CR with a given static CR are boost, altitude, cam timing, rod length, VE.

 

[Alky V6]

Here's a link to another DCR calculator. This one looks pretty good. Good information on this page, anyway.
http://cochise.uia.net/pkelley2/DynamicCR.html
Ah. Not as good as I was hoping.

 

[Alky V6]

Something to realize. The DCR calculators that I've seen so far do NOT take into consideration dynamic changes in engine VE at different rpm and boost levels. Something that would certainly change the dynamic compression ratio.

 

[Alky V6]

Take for instance a 'tuning effect' in the intake runner which, can raise intake pressure at the valve as much as 10 psi at high boost levels, as it is closing.

 

[Alky V6]

The new bump stick.

 

[Alky V6]

Some interesting intake manifold design links.

http://www.bufkinengineering.com/intake manifolds.htm

http://forums.hybridz.org/index.php/topic/61549-turbo-intake-plenum/

 

[norbs]

Interesting cam, looks like high lift big duration and narrow lobe centers. Specs please"

 

[Alky V6]

It is a big cam. Bigger than anything I would have imagined I would be using. The LSA is wider than anything I've used in the past. You're pretty much forced to widen the LSA as the duration numbers increase, to keep overlap area under control.
It's a dual pattern camshaft.

 

[norbs]

OK, we know its secret what is the ramp rate, is it anything like my TK lobe profile I have? Are you going to weld up the cam groove in the 1st main?

 

[turbobitt]

It is a big cam. Bigger than anything I would have imagined I would be using. The LSA is wider than anything I've used in the past. You're pretty much forced to widen the LSA as the duration numbers increase, to keep overlap area under control.
It's a dual pattern camshaft.

I would guess 270+ @ .050
AG

 

[Alky V6]

OK, we know its secret what is the ramp rate, is it anything like my TK lobe profile I have? Are you going to weld up the cam groove in the 1st main?

I don't have the ramp rate yet. I'm sure the rate is not too aggressive. I expressed valvetrain durability to be an important factor when I ordered the cam. I'll be exploring the cam soon. I'm curious to see what the ramps look like.
No. I will not be welding up the groove. Although, I would have preferred that it wasn't there. The groove may actually be a good thing with the geardrive, seeing that the load on the front cam bearing is in a different clock position than it would be using a chain drive. The groove will allow lube to be fed 360 degrees about the journal.

 

[Alky V6]

I would guess 270+ @ .050
AG

Correct.

 

[turbobitt]

I don't have the ramp rate yet. I'm sure the rate is not too aggressive. I expressed valvetrain durability to be an important factor when I ordered the cam. I'll be exploring the cam soon. I'm curious to see what the ramps look like.
No. I will not be welding up the groove. Although, I would have preferred that it wasn't there. The groove may actually be a good thing with the geardrive, seeing that the load on the front cam bearing is in a different clock position than it would be using a chain drive. The groove will allow lube to be fed 360 degrees about the journal.

What is the cam intensity level (difference between .020 and .050 lift ?). Should be a matter of just looking at the cam card. Would expect to see between 28-34 degrees.

Allan G.

 

[Alky V6]

What is the cam intensity level (difference between .020 and .050 lift ?). Should be a matter of just looking at the cam card. Would expect to see between 28-34 degrees.

Allan G.

The cam card is at the shop, but I don't recall it listing a .020" lift figure.

 

[turbobitt]

The cam card is at the shop, but I don't recall it listing a .020" lift figure.

Usually the .020 is the rated duration.
Allan G.

 

[Alky V6]

Usually the .020 is the rated duration.
Allan G.

Oh. You're talking about .002" or advertised duration.

 

[turbobitt]

Oh. You're talking about .002" or advertised duration.

Actually did mean .020. That is how comp rated them but I guess not everyone else.

For example, Comp TK's such as Norbs has an intensity level of 28 degress (266 rated - 238 at .050) and regarded as extreamly aggressive and actually the most aggressive ramps comp offers. My cam works out at 36 degrees and is very soft ramps for durability. From what i understand, anything below 32 degrees starts to become a challange to control and would require more spring compared to a less agressive ramp.

 

[norbs]

Actually did mean .020. That is how comp rated them but I guess not everyone else.

For example, Comp TK's such as Norbs has an intensity level of 28 degress (266 rated - 238 at .050) and regarded as extreamly aggressive and actually the most aggressive ramps comp offers. My cam works out at 36 degrees and is very soft ramps for durability. From what i understand, anything below 32 degrees starts to become a challange to control and would require more spring compared to a less agressive ramp.

The street cam I am using shows 37 so I should be ok..........

 

[turbobitt]

The street cam I am using shows 37 so I should be ok..........

Norbs,

Look again because if it is the exteam street profile lobes they are rated at .015 lift and not an apples to apples comparison.

If it is a the extream street it will be good anyway and designed to run at tight lash.

 

[Alky V6]

The intake has a difference (advertised minus .050") of 37, and the exhaust is 40.