About Cam specs

[fr0st]

Alright so I ordered what I thought to be a set of Crower 264/272 awhile back and they've been sitting in my closet for the longest time. I made the stupid mistake of not taking a closer look at the camshaft spec sheet that came with it.

So I'm going to install them and I see on the spec sheet that they are "custom grinds" with an advertised duration of in/ex 252/255. Now I'm thinking, "fucking shit wtf?" its been far too long and that place that I bought them doesn't carry that brand anymore as has told me i'm pretty much up shits creek.

Here is whats on the spec sheet (I'll grab a picture later as the camera is still in the car).

Engine Application: MITSUBISHI 4G63
Grind Number: SPECIAL

ADVERTISED CAMSHAFT SPECIFICATIONS: COLD
INTAKE: Duration: 252 Lift: .398 Clearance: .000
EXHAUST: Duration: 255 Lift: .381 Clearance: .000

The information below is for degreeing cam only. Correct only at .050" tappet lift.

INTAKE Opens -3.0ATDC
Closes 27.0ABDC
EXHAUST Opens 39.0BBDC
Closes -7.0BTDC

LOBE SEPARATION 109

DURATION @ .050" LOBE LIFT
Intake 204 .234
Exhaust 212 .224


Could the spec sheet be wrong or did I actually get a custom ground set instead? Is there ways to find out the specs of a cam if it is possible that the spec sheet is wrong?

I understand that the Evo1 cams are 252/252's with like 8.5mm of lift, so I'm assuming these cams would have little to no effectiveness on upgrade.

 

[milkandoj]

Heres what they advertise on their website. to compare the figures to. If you can convert your figures before and after TDC to thier numbers.
http://crower.com/cat/import/mitsu/cams/camshafts.shtml

However i found info that had their advertised values in a lower number. Maybe they now are using the same system as alot of the other companies so the numbers are comparable to the 264, 272, 280 ect numbers. And your "advertised duratrion" was written in the older system.


From a bit of a searching it looks like crower advertise their cams at .50 lift not at just after .00 when they start to open in the slightest like alot of the other brands. so the number will be lower. Its the number at .50 lift people end up comparing among the brands to see what they really are.

Like in the crower system at .50 lift the stage 4 was only 240 degrees. And the custom grinds were abonve 250, cant find the info again... If your number was based on this system you'd have quite agressive ones.

Found this on dsmtalk. in the "huge camshaft revied" thread.

Also as far as duration is concerned, the duration specs that Webcams and HKS list is a weird ass number. From the look of it, they get this number basing on the exact moment that the lobe lifts the valve even the tiniest amount (even though virtually no air is gonna be flowing through at this point). The standard way of rating cams is the way that Crower and some of the other American manufacturers rate them. That's why people think that the Crower cams are "crap" compared to HKS and Web. It's just that they use the standard of measuring duration.


though on their web site they use the more common system, maybe they changed over?

 

[fr0st]

ahh okay so what the numbers that are important are the numbers @ .50" lift ?

 

[milkandoj]

Yeah thats when the valve is actaully opening and letting air in. not when it starts to open a tiny tiny bit. if you can compare the lift at 50 thou to other cams you can make the comparison.

Like i said i dont actually know the system crower use or did use in the past to advertise their cams.
I did a bit of search out of interest, and i could only find people saying they "think" they did it at .50
But there was info out there saying they their advertised durations were less than other companies therefore people thought they were piss weak so it seams your are quite agresive if they are under that system.
But... their website lists them like most the other brands now.

Advertised duration mean little, but duration at .50 lift and if you know the max lift you can compare 272 hks to 272 bc to 272 crower for eg.

 

[milkandoj]

Found that link again. scroll about two thirds of the way down to, Mitsubishi/DSM 4G63 Camshafts (1st and 2nd Gen)
They are listed differntly. In lower numbers. If its correct and yours are listed in this way you got some pretty agresive cams there

The advertised duration isnt at at .50 lift as they have the specs for that there. (if they were say 240 degree at .50 the car prob wouldnt idle anyway)

AS i said before i dont know how they come up with the advertised number but the range is alot lower than other brands for the 4g63.

Also look at the other numbers listed for other motors on the page, they look more like what you'd expect, with the hot cams being around 270- 280.
Yet the 4g63 cams have such low numbers listed. I dont know why ill leave it up to other people to figure that one out.

http://www.raceraccessories.com/crower_cam.html

 

[BMGTZ]

I have a set of BC 272/272 sitting on the desk here , their blurb,

DURATION @ .050'' 212/212

so its possible, when compared to that info, your exhaust cam IS a 272 cam

 

[fr0st]

Yeah, I made that connection when looking at other mfg websites.

a blurb from a pm from me to milkandoj

BC's advertised 272 cams have a Duration @ 0.050" of 212. and 212+60=272, now assuming this would be the same for a 264 cam that would make it 204 @ 0.050". Just so happens to be the same duration @ .050 for the Crower cams.

Still doesn't explain why it says the advertised spec is 252/255.

I've been trying to find anyone else that have bought crower (not BC) cams to see what their spec sheets say.

What milkandoj was saying was that Crower used to advertise spec @ 0.006" instead of what other mfg's were using which was 0.000" and if it was by that then they would be really aggressive cams, however I have a feeling that is not the case.

 

[VR-4Squid]

Put them in, get it tuned, drive it.

oh and maybe post up a before and after dyno sheet too.

 

[Liberoz]

There's a lot of mix up when quoting cam shaft spec's adam at parry engineering has explained it to me also Camtech guys the old way was a lesser figure than the Advertised (phyical one is) if that makes sence

As squid said throw them in tune it and drive it