Let's talk cams

mfsuper90

mfsuper90

300ft is all I need
Joined
Feb 6, 2013
Messages
769
If like to get some feedback on different cam grinds, I run a 4 cylinder 318 Perkins, so pretty different than most.

What kind of cams are you guys running for low rpm grunt vs high rpm? And how does that effect boost/back pressure?

I know some like equal intake and exhaust duration, but I have seen that some 3000rpm engines are running a intake duration 20-40 degrees lower than the exhaust(200/240) and running 96-99 degrees of cam timing.

If a cam is installed at say 105 vs 98 degree, can it keep a turbo from spooling up correctly?
 
That is a loaded up question. Really hard to answer. All of it depends on the turbo, head, and then camshaft. The combination of the three together will give you different characteristics. Large duration differences are typical on diesel turbo charged engines, but it really depends on the turbo and housing size, then cylinder head flow. As far as setting cam timing: 98 -105 might change turbo spooling some, but really it is changing where, and how much peak torque you make. A lower intake CL will give you more pk torque lower in RPM where as a higher CL will lower the peak torque, move it up in rpm, but can also sometimes broaden the torque curve as well. Where you want the cam set can depend greatly on the turbo, and how you are using the engine.
 
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Sorry about the loaded question, i know there are a lot of variables. Thanks for taking the time to explain that.

The reason I ask is that my 318 Perkins has a s257sx-e on it, and we are having trouble getting it to light. It makes around 22lbs of boost with 18lbs back pressure. It makes boost, but never really gets on top of the charger. It is super lazy and never cleans up the fuel put to it. Tried originally a 1.00ar exhaust and it only made 15psi, so I then moved to a .82 and it raised to to the 22/18lbs. The head flow is poor, Simese ports. And it runs a Bosch VE with exhaust temps reaching 1500f

What I am trying to get at is, if the cam was ground for an engine that is meant to run 5-6k rpm and my engine only turns 3500rpm, could the cam be the culprit?
 
I subscribed to this thread when you posted it for camshaft insight. Now I want tho know more on this Perkins performance quest your on.
 
That would be a great follow up thread!

Just so you know, I'm not as smart as I think I am.
 
99GreenCummins said:
Nitrous....
Click to expand...

As if I didn't give them enough to complain about already LOL

We have been messing with Perkins for awhile now. First started out with the 6.354 and now the 4.318
They both are for farm stock pullers, just something fun to play around with. It's definitely more of a challenge to work with the Perkins, cause you can't just call up hypermax or riverside and order parts for them, everything is custom.
 
Originally it was a 242/242 with a 107 lobe seperation degreed at 105. That ran for 8 years NA. Now when we turbo'd it I called crower and had them do a regrind on it for the turbo, because I was have problems with it spooling.

So now it has a 242/238 on a 110 lobe separation degreed at 105. And that cam changed nothing for my setup. The more I look at different cam grinds, the more I don't think this cam is correct for my setup, but I don't know if it will solve my spoiling issues?

This engine should spin the heck out of this little s257, but it doesn't. I sized the charger kinda small because I didn't have huge power goals, and it's still struggling. I even took the charger apart to make sure the bearings weren't messed up.
 
That's a bit much camshaft. The gas cam grinding companies are okay if you give them numbers, but never let them decide what cam a diesel needs.
 
That is way too much camshaft for your turbo, engine, head combination. I can help you get in the right area for what you are doing. Give us call: 715-384-4422
 
I'm assuming this is a diesel right. VE Bosch pump. Just kind of confused as you said you ran that big cam when the tractor was NA. Even for NA that cam would have been too big if it was a diesel. If that tractor runs gas, then it is a whole different story.
 
EricStaab said:
I'm assuming this is a diesel right. VE Bosch pump. Just kind of confused as you said you ran that big cam when the tractor was NA. Even for NA that cam would have been too big if it was a diesel. If that tractor runs gas, then it is a whole different story.
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Yes this is diesel, I ran this cam for 8 years. I am not saying it is right, but somehow that's what we got set up with when we did this engine. I am very new to cam designs. This turbo project has been the first time I have messed with them. I've been talking to a lot of guy and doing a lot of research trying to learn about performance.

A friend of mine runs a 3000rpm 570 IH and he showed me his cam specs, which is what led us to believe the cam ground for my Perkins is not right for what we are doing. I thought it was odd that crower didn't ask me any details about my engine, but I figured they should know more than I :nail:
 
Cam has been sent to Eric at No limit, updates will come whenever it is done and put back together
 
99GreenCummins said:
You've been busy! Between planting and tearing down the tractor.
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Who says the tractor is tore down? :lolly:

I got a stock cam off Huck brothers and sent it instead of tearing it down. I don't have time to tear apart my tractor right now haha
 
Small update, found out I was looking at the "advertised" numbers instead of numbers at .050". Whatever advertised even means. :doh:
So in reality it is actually a 206/206, which is much more reasonable than previously thought. But still not quite right for optimum, so I am working with Eric at No Limit on getting a correct regrind. He's been great to work with!

Turn out that having it degree'd in at 105 was probably fairly radical and should've been backed off. If I didn't have to pull the entire front end off to change cam timing, I would try it with the 206/206 I have now, just for kicks and info. But ain't nobody got time for that, so I'll just wait for the cam.

Also on the hunt for a little heavier valve spring just for safety (but mostly cause Eric recommended I bump it up some) stockers sit at 50lbs at the seat. You common engine guys (cummins,jd,IH) got it easy finding your parts! The search is on.
 
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