I'd convert to shim-under (Or shimless) anytime you're talking about a reground cam. Increasing lift on a ground cam involves decreasing the base circle.

Taking that up involves thicker shims. Thicker shims on a shim-over setup is ******.

 

272 is just the duration. Its meaningless.

 

I assume the MSM was engineered by accountants, not engineers.

 

Think of it like the RWD Mazdaspeed Protege. Engineered and designed by engineers. Then completely assfucked by accountants.

 

I thought that was every car.

 

It is, but it's way worse in the under $30k turbo limited release segment.

 

There's still some that sneak by. Like the C63 AMG or the Magnum SRT-8. They must have tied up the bean-counters.

 

I know this. But I'm not going to type out the entire measurements when I can just say 272 and anyone with common knowledge would know your taking about aggressive cams. Unless your taking v8. Then I should just say aggressive cams. My bad.
Meanless, no though, very important.

Turbo= high duration/short lift
N/A= short duration/high lift
Correct? Simplified
Also I like ******.. but no seriously.
I've looked into cams and have supertek double springs, solid under shim as the setup. Which would be marvelous for 8k red line.

 

I tend to run them the other way around - big duration (with the right headwork) helps NA engines scavenge well and helps create power.

High lift with shorter duration reduces overlap but allows peak flow figures for a long duration than stock. Perfect for a turbo.

 

It's really not that simple, anyways.

Next cam for my daily driver will have huge exhaust duration and lift. Short intake duration, big-ish lift.

 

Indeed, engines are never really simple. Besides No replacement for displacement and Turbo = awesome.

Wait, did I get it backwards?
Is it
Turbo= short duration/high lift
N/A= high duration/short lift

 

Really depends on the motor. I don't know that turbo BPs like.

I want both high duration and lift on the exhaust of my motor because my combined exhaust valve area is about the size of a mushroom stamp.

 

I was told
Turbo= high duration/short lift
N/A= short duration/high lift
Talking intake, by a reputable Honda engine builder.

I wonder what it's like for Turbo BP. Anyone have inside on this?

Also, what kind if mushroom stamp? Black? Yellow?

 

This sounds very wrong. Not to mention oversimplified.

Longer duration is a necessity when an engine is operating at high rpm, regardless of it being naturally or force aspirated. In the case of being supercharged or turbocharged you typically would need less duration to get the same affect because of the positive pressure, but it has a lot more to do with the engines speed than anything. More revs means less time for cylinder filling and evacuation to happen, which means you need more duration.

Lots of duration comes with added effects on valve timing (late intake valve closing in particular) which are often really bad for turbo engines. So if anything I would say that its the exact opposite of what this builder told you.

Turbo cams usually use high lift to get the flow that they cant get from long duration. Ive even heard of people buying turbo specific cam grinds and actually losing peak power because the grind has less duration than stock (with more lift and an advanced intake profile). They gain spool and a lot of mid range, but up at high rpm the cams lowered duration makes the engine run out of breath.

 

What full tilt said !!!! And let's speak of duration @.05 or 1mm , advertised duration is useless

 

Maybe it's a Honda thing. Or he was just talking out his ***. He also sarcastically said gridlock with my Wiseco pistons.

Short duration seems more oriented to boosted cars, like you said, since the air is being forced in it should need a long.

So, just run massive duration/lift for ALLOFIT


Ctdrftna, your cans were custom weren't they? Remember the specs?

 

Mine are the massive/ALLOFIT cams you speak of. The specs are

296(260 something at .05) .495 lift intake
282(250 something at .05) .455 lift exhaust

I will be running different cams when this motor goes into my new car

 

CT, your cams seem like a good match for my all motor build. we should chat.

you would have had to clearance the head, but did you have any problems with standard valve guides being too long with that much intake lift?

 

The head is clearanced, I'm running the supertech dual springs without the inner spring, and a .015 shim to get my spring pressure right. I have bronze guides , but I don't think they are any different dimensionally from stock. I know I'm close on retainer to seal clearance. But iv had no problems with these cams.

I did replace a few mazda comp lifters over the winter because they had some funny marks on the top . Looked like the chrome playing came off or something.

 

The RPM range of those were like 5000-10000 rpm right? It's been awhile since I read the build thread.
I wouldn't mind a max 7200 or 7500 rpm cam.