Are you all seeing an influx of over cammed combinations?

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Krooser
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Re: Are you all seeing an influx of over cammed combinations?

Post by Krooser » Fri Oct 27, 2017 1:56 pm

Krooser wrote:
Fri Oct 27, 2017 1:54 pm
bigpoppapreston wrote:
Fri Oct 27, 2017 1:24 pm
stangbuilder wrote:
Fri Oct 27, 2017 1:15 pm
Funny reading this, I am 62 years old been down that road to many times.I now drive a 67 mustang with a 477 in fe that came off dyno at just south of 700 hp..It idles at 700 rpm with efi..and it smooth....I can pull 5th gear at 1200 rpm and drive away with no issues smooth..By the way the cam one of jones grinds 238 242 at 50. Its a soild flat tappet deal...Pulls like a frieght train to about 6800 to 7000 rpm. Car only weights 3100 without me. And.I shit you not.The car is a hand full to drive running it through the gears on street tires
LOVE IT!!!
After seeing that an old Duntov 30/30 cam is too big for a .030 over 283 with a two barrel and stock manifolds in a '61 Impala ragtop daily driver I've S-L-O-W-L-Y learned that bigger isn't always better... took 50+ years!

My kid's dirt b-mod shocked the cr*p outa him, me and the cars PO a few years ago after the kid's nicely 'built on a budget' 355 showed incredible acceleration of the corners using one of Mike Jone's relatively mild grinds... the guy who previously owned the car looked at the cam specs and declared it was suitable for a street stock but was way too mild for a modified. Made a believer out of him. The 'freight train' analogy is spot on IMHO.

Now Mike is going to grind another flat tappet cam for my low buck dirt late model 383... again the specs seem pretty tame but I trust his advice. Most guys are running 10 degrees more duration and another .25 more lift with heads that don't flow what mine do. Of course they are spinng those motors 800-1000 rpm's more than I plan on doing.

My good friends SBC WISSOTA spec, Brodix headed 358 SBC is another one with a way bigger cam than some would suggest. And it's an old I*ky grind that is likely 30 year old technology. He now sez he needs even more to keep up... I'll see if he listens to reason.
Last place in the B-main is better than anyplace in the grandstands...

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Re: Are you all seeing an influx of over cammed combinations?

Post by lefty o » Fri Oct 27, 2017 2:56 pm

Rick Finsta wrote:
Fri Oct 27, 2017 7:35 am
Mark O'Neal wrote:
Fri Oct 27, 2017 4:56 am
There is a distinct reason why I chose to run the 3/4 race cam instead of the 1/2 race.
Being asked if you have a 1/2 or 3/4 cam in your car is like being asked to play Freebird when you're on stage. You think it is just an industry joke until it happens to you.
the correct answer when that happens is "i put the whole cam in it"!

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Re: Are you all seeing an influx of over cammed combinations?

Post by joe 90 » Fri Oct 27, 2017 5:16 pm

kimosabi wrote:
Fri Oct 27, 2017 9:36 am
Be it VVTi, Vanos, Vtec etc all they do is change the cam timing. Duration is the same. Lobes don't change.

Hope and change!
No......Honda's early VTEC uses 2 different cam lobes.
As does Mitsubishi's early mivec
As does Nissan's SR20VE

Most of the others are V V T.

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Re: Are you all seeing an influx of over cammed combinations?

Post by kimosabi » Fri Oct 27, 2017 6:19 pm

joe 90 wrote:
Fri Oct 27, 2017 5:16 pm
kimosabi wrote:
Fri Oct 27, 2017 9:36 am
Be it VVTi, Vanos, Vtec etc all they do is change the cam timing. Duration is the same. Lobes don't change.

Hope and change!
No......Honda's early VTEC uses 2 different cam lobes.
As does Mitsubishi's early mivec
As does Nissan's SR20VE

Most of the others are V V T.
Intake cam vs exhaust cam you're right. I guess if you add and subtract a little and mix in cam timing you do get "variable duration" on the cylinder.

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Re: Are you all seeing an influx of over cammed combinations?

Post by Fireonthemountain » Fri Oct 27, 2017 6:34 pm

stangbuilder wrote:
Fri Oct 27, 2017 1:15 pm
Funny reading this, I am 62 years old been down that road to many times.I now drive a 67 mustang with a 477 in fe that came off dyno at just south of 700 hp..It idles at 700 rpm with efi..and it smooth....I can pull 5th gear at 1200 rpm and drive away with no issues smooth..By the way the cam one of jones grinds 238 242 at 50. Its a soild flat tappet deal...Pulls like a frieght train to about 6800 to 7000 rpm. Car only weights 3100 without me. And.I shit you not.The car is a hand full to drive running it through the gears on street tires
Sounds kinda like my Toyota PU except with my lower rpm requirements, and less weight, and a few less cubes. 222 and 230 @.050 Crane hydraulic at 110. The injection tames the idle, with its force fed fuel no longer dependent on high stable vacuum, or bothered so much by the otto cycle. It tamed the previous larger cam in it the same way. But still prefer a carb really for many reasons.

stangbuilder
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Re: Are you all seeing an influx of over cammed combinations?

Post by stangbuilder » Fri Oct 27, 2017 7:22 pm

Well as i said im 62 and have had so many hot street cars i really lost count.Many sbc@ bbc.honestly this is my first ford. not that it really matters.For a FYI.This is my first EFI deal.. No shit i will never run a carb on the street again..racing thats another story. This car had a carb on it that was highly tuned Put Efi on it. Its really hard to find anything wrong with Efi

starts better cold@ hot
response is second to none
gas mileage
lap top tune. The tuning is everything most old hot rod guys dreamed about You think about it you can do it.

Downside cost.....

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Re: Are you all seeing an influx of over cammed combinations?

Post by joe 90 » Fri Oct 27, 2017 8:24 pm

kimosabi wrote:
Fri Oct 27, 2017 6:19 pm

Intake cam vs exhaust cam you're right. I guess if you add and subtract a little and mix in cam timing you do get "variable duration" on the cylinder.

2 different intake profiles, different lift and duration.
2 different exhaust profiles, different lift and duration.
They switch using oil pressure activated by the ECU switching at about 4500 RPM.

The small cams make a peak torque at 3500 to 4000 RPM, the big cams make peak torque at 5000 to 6000 RPM, combined with a switchable intake runner length, end up with a flat torque curve from idle to over 8000 RPM.

From the factory.



"Over cammed".....that just means it was done wrong.

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Re: Are you all seeing an influx of over cammed combinations?

Post by peejay » Fri Oct 27, 2017 8:52 pm

kimosabi wrote:
Fri Oct 27, 2017 9:36 am
Be it VVTi, Vanos, Vtec etc all they do is change the cam timing. Duration is the same. Lobes don't change.

Hope and change!
Your ignorance is showing here. But that is to be expected of someone who uses "hope and change" in that manner.

VTEC has separate low and high RPM lobes and followers, and oil pressure runs a pin between the high RPM lobe's rocker and the low RPM lobes' rockers, which are the ones thsat actuate the valves. There are separate high and low RPM lobes with different durations and lifts.

Toyota had a similar setup. (Not sure if they still do)

Subaru has a similar setup on the SOHC engines. They have different lobes for each intake valve, and at high RPM they pin the low-duration rocker to the high-duration one.

Volkswagen/Audi have a truly bizarre setup. They have sliding lobes on the camshaft. There are two different lobes, a high RPM and low RPM lobe, that can shuttle on the camshaft. They have the same base circle. When they want to switch from low to high or high to low, a pin comes out of the actuator and hits a cam/ramp on the "lobe shuttle" with its ramp starting when the cam is at its base circle. I have pictures but Photobucket doesn't allow hotlinking anymore.

These are only the systems that I have direct experience with, but suffice to say that that there millions of engines on the road that have variable duration via multiple lobes per valve. Honda has been doing it first on high end models since 1989 and eventually on more-or-less everything they marketed since ten years ago or so. Subaru has it on everything with a SOHC 2.5 made in the past ten years or so. Everything you see with a VWAG "2.0t" has it.

And don't get me started on Valvetronic. There is some very interesting geometry happening in that valvetrain! Technically it's the same lobe but the way they cam the variable lift gives if effectively variable duration, unless you believe that sub-.050" lift is important. The "dead lift" starts at the extremes of opening and closing and works towards the nose of the camshaft. They're able to control valve lift to the point that the engine will idle dead smooth at 700-800rpm with the throttle plate wide open... (The wonders of drive by wire! There's no WAY you'd be able to pull this off without it)

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Re: Are you all seeing an influx of over cammed combinations?

Post by kimosabi » Sat Oct 28, 2017 9:01 am

Well hey I'm not really serious when it comes to what politicians say(they say alot of shit) but thanks for the writeup. I have no problems what so ever being factually corrected and sometimes that is needed when my thick skull rely on my own experience too much.

Very interesting stuff. What are the reliabilty on these systems? I would guess oil change intervals are very important.

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Re: Are you all seeing an influx of over cammed combinations?

Post by MikeB » Sat Oct 28, 2017 9:13 am

tresi wrote:
Thu Oct 26, 2017 11:00 pm
I see a lot of "No, that cam won't due I need at least .550, .600, .630 or whatever lift". They vaguely have an idea of what duration is all about and never heard of lobe separation.
Yeah, there are plenty of guys who choose a cam based on its idle quality, with no clue about any specs other than lift and maybe advertised duration. These are typically the cars that sputter and stumble up to 3000 RPM and could be out-accelerated by a stock 300 hp/327 Chevelle with a 195/202 cam.

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Re: Are you all seeing an influx of over cammed combinations?

Post by DaveMcLain » Sat Oct 28, 2017 9:24 am

peejay wrote:
Fri Oct 27, 2017 8:52 pm
kimosabi wrote:
Fri Oct 27, 2017 9:36 am
Be it VVTi, Vanos, Vtec etc all they do is change the cam timing. Duration is the same. Lobes don't change.

Hope and change!
Your ignorance is showing here. But that is to be expected of someone who uses "hope and change" in that manner.

VTEC has separate low and high RPM lobes and followers, and oil pressure runs a pin between the high RPM lobe's rocker and the low RPM lobes' rockers, which are the ones thsat actuate the valves. There are separate high and low RPM lobes with different durations and lifts.

Toyota had a similar setup. (Not sure if they still do)

Subaru has a similar setup on the SOHC engines. They have different lobes for each intake valve, and at high RPM they pin the low-duration rocker to the high-duration one.

Volkswagen/Audi have a truly bizarre setup. They have sliding lobes on the camshaft. There are two different lobes, a high RPM and low RPM lobe, that can shuttle on the camshaft. They have the same base circle. When they want to switch from low to high or high to low, a pin comes out of the actuator and hits a cam/ramp on the "lobe shuttle" with its ramp starting when the cam is at its base circle. I have pictures but Photobucket doesn't allow hotlinking anymore.

These are only the systems that I have direct experience with, but suffice to say that that there millions of engines on the road that have variable duration via multiple lobes per valve. Honda has been doing it first on high end models since 1989 and eventually on more-or-less everything they marketed since ten years ago or so. Subaru has it on everything with a SOHC 2.5 made in the past ten years or so. Everything you see with a VWAG "2.0t" has it.

And don't get me started on Valvetronic. There is some very interesting geometry happening in that valvetrain! Technically it's the same lobe but the way they cam the variable lift gives if effectively variable duration, unless you believe that sub-.050" lift is important. The "dead lift" starts at the extremes of opening and closing and works towards the nose of the camshaft. They're able to control valve lift to the point that the engine will idle dead smooth at 700-800rpm with the throttle plate wide open... (The wonders of drive by wire! There's no WAY you'd be able to pull this off without it)
A couple of weeks ago I had a set of Honda V6 heads come through the shop and one head had a normal SOHC mechanical cam setup with adjustable rockers. The other head also had solids but was fitted with a variable valvetrain setup that I have not had a chance to read about yet. It was simple enough to remove, wash and replace after I was done working on the head. This one had a single guide broken off even with the head. The customer was a shop that was fixing a very high oil consumption problem and I think that was the source of a lot of the oil. What do they call that system? Is it similar to the VTEC as used on a lot of their four cylinder engines?

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Re: Are you all seeing an influx of over cammed combinations?

Post by peejay » Sat Oct 28, 2017 10:00 am

It sounds like you were dealing with a variable displacment engine. I couldn't tell you what name Honda came up for it, although the idea of trying to squeak a couple more tenths of a MPG from a 4000 pound tank is silly in my mind. I guess they don't feel that the turbo 2.4l already in inventory is adequate.

Being a V6, to disable half the cylinders and still have an even firing order, you have to disable an entire bank. That bank (the front one IIRC) ends up running a lot cooler than the running one.

Oil consumption is a well known issue with these engines, and I believe they have a warranty extension. The warranty repair is new rings on the "cold" bank, maybe new pistons too, it's been a while since I had read about that little fiasco. I do remember that they were only pulling one of the heads off, and the dealership labor pay time was only 6-8 hours or so. Probably could even do it with enough practice. Of course, a valve guide broken off would be an even greater cause of oil consumption :)

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Re: Are you all seeing an influx of over cammed combinations?

Post by hoffman900 » Sat Oct 28, 2017 10:05 am

kimosabi wrote:
Sat Oct 28, 2017 9:01 am
Well hey I'm not really serious when it comes to what politicians say(they say alot of shit) but thanks for the writeup. I have no problems what so ever being factually corrected and sometimes that is needed when my thick skull rely on my own experience too much.

Very interesting stuff. What are the reliabilty on these systems? I would guess oil change intervals are very important.
They're all very reliable. 200k miles seem to be what 100k miles was in the yesteryear. Oil changes in the 5000-7000 range. Some of these have an issue with hot oil temperatures. Road racers that can't block off the VTEC due to rules (think showroom stock kind of prep) sometimes run into issues with hot oil reducing viscosity which will disable the VTEC.

That said, duration at .050" tells you nothing. Duration at zero lash tells you a lot more.
-Bob

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Re: Are you all seeing an influx of over cammed combinations?

Post by digger » Sat Oct 28, 2017 5:12 pm

The Honda stuff stills seems to make crap torque/L and lowend even with VTec go figure.

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Re: Are you all seeing an influx of over cammed combinations?

Post by joe 90 » Sat Oct 28, 2017 6:36 pm

80 ish ft lbs per litre.
How would that compare to a big V8........6 litres?
480 ft lbs?
All the way from idle to 8K.

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