Load of [censored], or Truth?

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Originally Posted By: BuickGN

I agree with you that specific output has gone up significantly in modern cars on average but it has nothing to do with valvetrain requirements.


Well, maybe not "nothing" but certainly very little. While cams are very aggressive they're all rollers now.

We have already experienced the "heartbreak" of a beautiful engine we built in an old Chevy PU that was destroyed by using new Mobil 1 in it!

The guy came back to me and could not figure out what had happened. Luckily the motor was easily repaired with almost all new valve gear, but now everyone is quite careful about what oil they grab off my shelf.
 
Pennzoil/QS:

Dear Dylan,

Thank you for your inquiry.

The zinc and phosphorous (ZDDP) levels were reduced in passenger car
motor oils as there had been concerns that the oil that makes its way
in to the combustion zone of your engine, carrying these anti-wear
metals, were burning and poisoning the catalyst in the catalytic
converters. If you are seeking higher ZDDP content you could use a
heavy duty diesel engine oil such as Shell Rotella T 10W-30 which
contains approximately 40-45% more anti wear additives. This motor
oil is perfectly acceptable to use in a gasolone engine and exceeds
API SM performance specifications.

Should you desire to speak with a technical representative to discuss
this issue in more detail please call Pennzoil-Quaker State Technical
Information at 1-800-237-8645.

Sincerely
Product Technical Service -RM
 
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Originally Posted By: Robenstein
Only the government would push an oil company to save your emissions equipment over your engine.


LOL, whacked statement of the week.
 
BuickGN "smaller base circle and narrower cam lobe"??
Smaller and narrower than what?
OHC engines have smaller cams.
Because of this, they use lower spring pressures.
 
Originally Posted By: mechtech2
BuickGN "smaller base circle and narrower cam lobe"??
Smaller and narrower than what?
OHC engines have smaller cams.
Because of this, they use lower spring pressures.


In general OHC engines tend to use a larger base circle coupled with a wider lobe and lifter/tappet than a pushrod engine, reducing the cam to lifter load. Coupled with the typically lighter spring pressure and the cam acting in a 1:1 action with the valve instead of magnifying spring pressure with a 1.5 or 1.6:1 rocker ratio, there's significantly less pressure there.

OHC engines usually have more aggressive cams from the factory and most of the time they're physically larger too.

I can compress the springs in my TL by hand and it spins to 7,000rpm. I can't compress the springs in the GN unless I stand on them and it typically operates in the 5,200rpm range.

Of course there are exceptions to all of this. To tell you the truth, I'm not entirely sure on the base circle part, I should've stated that before but I'm pretty sure it reduces load.
 
Try to think of the effect of the base circle sort of (and in really poor analogy) to running over a speed bump.

If the base circle is big enough, it's analogous to running over a gentle rise (albeit at a higher speed, proportional to the base circle diameter). As small base circle is a speed bump in a car park, you are going slow, but the sides are near vertical.

It's a rubbish analogy, but best I can come up with ATM.

Smaller base circles typically have higher peak pressures.

Larger base circles allow a cam designer more room to put in ramps to remove lash, alter lifter accelerations, and do tricks.

An infinitley small base circle sort of "slaps" the lifter into opening.
 
nice post.

I've always been told by those "in the know" that it's not how far the valve is opened but how fast when it comes to durability.
 
Originally Posted By: SteveSRT8
Originally Posted By: BuickGN

I agree with you that specific output has gone up significantly in modern cars on average but it has nothing to do with valvetrain requirements.


Well, maybe not "nothing" but certainly very little. While cams are very aggressive they're all rollers now.

We have already experienced the "heartbreak" of a beautiful engine we built in an old Chevy PU that was destroyed by using new Mobil 1 in it!

The guy came back to me and could not figure out what had happened. Luckily the motor was easily repaired with almost all new valve gear, but now everyone is quite careful about what oil they grab off my shelf.


Very interesting. Which of the 19 or 20 different varieties and weights of Mobil 1 did you use to break-in this engine?
 
Originally Posted By: Shannow
Try to think of the effect of the base circle sort of (and in really poor analogy) to running over a speed bump.

If the base circle is big enough, it's analogous to running over a gentle rise (albeit at a higher speed, proportional to the base circle diameter). As small base circle is a speed bump in a car park, you are going slow, but the sides are near vertical.

It's a rubbish analogy, but best I can come up with ATM.

Smaller base circles typically have higher peak pressures.

Larger base circles allow a cam designer more room to put in ramps to remove lash, alter lifter accelerations, and do tricks.

An infinitley small base circle sort of "slaps" the lifter into opening.


Thank you. That's kind of how I was picturing it in my head but then I remembered I had never specifically read anything on the subject.

I've got a pretty high ramp speed (for a flat tappet cam) in the GN. Duration is only 212 degrees on both the intake and exhaust but I'm always worried about this thing going flat on me and taking the engine with it. I'll probably go with a roller next time I get into it just for peace of mind.

It's kind of neat looking at a roller and flat tappet with roughly the same duration and lift next to one another. The roller has a flatter lobe at the nose, you can actually see with your eyeballs that it has much faster ramp, leaves the valve nearly fully open longer then closes it quicker to end up with the same overall duration. I know you know this, just thinking out loud.
 
Originally Posted By: Robenstein
Only the government would push an oil company to save your emissions equipment over your engine.


Ain't that a pip
 
would be IF govt was driving GF-5.

It's the manufacturers who can't keep the oil in the sump driving it 'though.
 
Originally Posted By: badnews
Originally Posted By: Robenstein
Only the government would push an oil company to save your emissions equipment over your engine.


Ain't that a pip


In a way, it is the government pushing, but, as I understand it, the manufacturers pushed for the SM oil because of the government ruling that cats must be warranted for 125,000 miles instead of the previous requirement of 80,000 miles.
 
More info, Read from bottom up:

Quote:

From: Dietz Brock
To: Dylan Maxwell

I don’t have one for Super Tech so I attached the spec sheet for Mag1 which has the same specs as the Super Tech.



From: Dylan Maxwell
Sent: Monday, April 26, 2010 4:45 PM
To: Dietz Brock
Subject: Re: Super Tech



Thanks, Ill look into it next time Im in town.
Can I get a spec sheet for the 15w40 "Universal" Oil with the Diesel Classifications too? (The jugs are WPP or WNE Marked)
Sorry, Im not sure exactly what its called. It was marked for gas/diesel fleets.

Dylan





From: Dietz Brock
To: Dylan Maxwell
Cc: Mari Santa
Sent: Mon, April 26, 2010 4:53:54 PM
Subject: RE: Super Tech

Dylan,

We have a product at Walmart, Accel 10W-40 "SF" motor oil which contains
zinc at the levels you might be looking for. The only issue is API approval
level "SF" is for most 1988 vehicles and earlier and you have a 1989
vehicle. You might want to check the owner's manual and see what API
quality level you need for your 1989 vehicle. I've gotten numerous requests
from customers with older model vehicles looking for a product that contains
zinc. They usually end up getting the Accel product and I haven't gotten
any complaints that it's not performing. I've also heard that there is a
product out there that you can add to modern day oils to increase your zinc
level but I haven't seen it or would know where to find it. Walmart's
retail price for the Accel 10W-40 SF is $2.17 a quart.

Attached are the specifications for Accel 10W-40 "SF" your reference.
Hopefully this helps with your decision and let me know if you have any
other questions.

Dietz Brock

-----Original Message-----
From: Mari Santa
Sent: Monday, April 26, 2010 2:18 PM
To: Dylan Maxwell
Cc:
Subject: Re: Super Tech

Dylan,

My apologies, this is the first time I have received your e-mail.

I am forwarding your request to our Super Tech expert. He should be
responding to you shortly.

Thank you


Mari Santa
Warren Distribution
Customer Service Manager



>>> Dylan Maxwell 4/26/2010 2:13 PM >>>
I sent you this email a couple days ago and have not recieved a response. I
would really appreciate it if you would respond, as I would like to know.

Im wondering if any of your "Super Tech" branded products are
recommended for Flat Tappet cams (89
Cherokee, 4.0l) to prevent premature Valvetrain/cam wear.
I am worried that the amount of zinc in my current oil may be too low and
am looking for something I can find at the local Walmart that
isnt too expensive.
Thanks,
Dylan
 
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