Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
Big valves/Hot Cam vs. Smaller valves/Hotter Cam
Page: Previous  1, 2, 3, 4  Next
Forum Index -> Performance/Engines/Transmissions Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
Alstrup
Samba Member


Joined: July 12, 2007
Posts: 7183
Location: Videbaek Denmark
Alstrup is offline 

PostPosted: Fri Oct 22, 2021 10:19 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Pretty good explanation Tom.

While I basicly agree I will say, that I hardly ever let the engines breathe "that" well on top to let say the 86B peak above 6500. There is a trade off, and that is driveability on the street, and since 95% of the ACVW engines I build are street engines I focus somewhat on usable power in the lower rpms too, which typically means that an engine with a cam like the 86B peaks in the 5800-6300 rpm range. Some of you have seen me write APB once in a while (Average Power Band) With APB calculations from a dyno pull you can soon see if an engine makes more power from a certain change in set up, or if it just moves power around. The latter is what happens the most when we swop parts, but sometimes we actually hit a creek of small improvements.

With the 86a. Opinions vary of course, bus I stand by my comment. - Some of it - may be me expecting more from it (numbers) than it will ever support. In a type 1 set up it will lift the valves about 0,033" moire than in a type 4 set up, but I doubt that will make any significant difference in behaviure. In type 4īs at least, say a 2056 cc) it typically pulls about 5 hp more peak than the 163 or 163/86b, - with the same CR. (between 9 & 9,5) But, midrange torque is less, by a good deal, and when it hits peak it is all over. The cam is so mild that you can easily use quality HD sgl springs with it in a good set up. You can say that the 86a is good for people that want to run 1,4 ratio rockers , but are skeered of valve lift.
IMHO a Web 163 is an awesome cam in that segment. May not pull the highest peak hp, but the torque pattern (APB) is very hard to beat, meaning that the engine makes POWER and not just pulls rpms.
The FK7 is basicly a W110 on steroids. Its an ok cam as such, but as the W110 it is old, and we can do so much better today. since such cam should be run with dual valve springs after all you might as well go FK42, THATīS a nippy cam with good power potential.
As for other cams in that segment donīt overlook the CB 2242. With say 1,25 rockers this cam has a lot of potential, and is mild on the valve train.
Also the SLR XR 292 aint bad. May be a little down on peak hp, but good allround torque.

As always, the power is in the combo, so chose your parts right.
Iīm all in for the "downsizing" of valves etc. But if you are not carefull you might end up with something different tan what you were after. I see several P heads on large engines these days because some ads show massive numbers with them. Iīm sorry to say, these heads are not off the shelf heads, they are up to heavily reworked. In stock form the P heads have outlived themselves at approx 2165 cc. more displacement than that and you loose upper end power and gain some lower rpm torque. You could build a 2275 "bus" engine with a FK8 bumping the valves and the engine will be docile as a stocker (almost) but will eat its way through the rpms due to the cam duration, but it will stop at about 150 hp and 230 Nm torrque. The heads simply canīt breathe more than that, and there is not enough rpm to recover flow from the ram effect. Put a set of detailed hand ported heads with same valve size on the same engine and you will soon see 10-15 hp and up to 10 Nm more torque over a wider powerband.

End of rant Rolling Eyes
Hope this helps.
_________________
https://www.thesamba.com/vw/forum/viewtopic.php?t=435993
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Danwvw
Samba Member


Joined: July 31, 2012
Posts: 8892
Location: Oregon Coast
Danwvw is offline 

PostPosted: Fri Oct 22, 2021 3:45 pm    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

1679cc W-100:

Link

_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!
Back to top
View user's profile Send private message Send e-mail Facebook Twitter Gallery Classifieds Feedback
Bad bug
Samba Member


Joined: March 11, 2006
Posts: 1119
Location: Jamaica
Bad bug is offline 

PostPosted: Fri Oct 22, 2021 5:37 pm    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Brian_e wrote:
X3

When I am running different combos through the analyzer programs, I will always go for the combo with the highest average torque, over peak HP numbers. Lots of low end, and a wide powerband will be WAY nicer to drive than an extra 5hp for bragging rights.

Brian


agree.
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
bw65vw
Samba Member


Joined: August 04, 2020
Posts: 149
Location: Tennessee
bw65vw is offline 

PostPosted: Fri Oct 22, 2021 6:58 pm    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Thanks very much for the reply and explanation Alstrup. I was looking at the cam info for the web 163 and it is
Lift 429/.429
Duration 288°/288°
Duration @ 0.050" 250°/250°

The stats for the 86A is
Lift 502/.502
Duration 290°/290°
Duration @ 0.050" 252°/252°

Looking at this it seems the biggest difference is the lift which is actually higher for the 86A unless I am looking at the wrong one on their sight
Back to top
View user's profile Send private message Gallery Classifieds Feedback
bigbore
Samba Member


Joined: December 19, 2003
Posts: 3296
Location: Wasilla Alaska
bigbore is offline 

PostPosted: Fri Oct 22, 2021 7:22 pm    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

I build my bus engine's for low end power long life and fuel economy. the 1776s and 1904s I build pull power below 4000 rpm where a bus lives and get 24-25 mpg and pull a trailer (well maybe not at that mpg) I get many a year of daily driving pleaser fishing and camping Iam not tiring to set ant land/speed record's.
_________________
where its cold and snowy
Back to top
View user's profile Send private message Send e-mail Classifieds Feedback
Brian_e
Samba Member


Joined: July 28, 2009
Posts: 3228
Location: Rapid City, SD
Brian_e is offline 

PostPosted: Fri Oct 22, 2021 7:57 pm    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

bw65vw wrote:
Thanks very much for the reply and explanation Alstrup. I was looking at the cam info for the web 163 and it is
Lift 429/.429
Duration 288°/288°
Duration @ 0.050" 250°/250°

The stats for the 86A is
Lift 502/.502
Duration 290°/290°
Duration @ 0.050" 252°/252°

Looking at this it seems the biggest difference is the lift which is actually higher for the 86A unless I am looking at the wrong one on their sight


The 163 has slightly quicker ramps which open the valves faster, and make more area under the curve for the flow. This seems to make them pull harder and have a little more ”character”. If the cam is ground correctly, a faster ramp cam will still be quiet and last.

Brian
_________________
www.type-emotorsports.com
Back to top
View user's profile Send private message Visit poster's website Facebook Instagram Gallery Classifieds Feedback
stevemariott
Samba Member


Joined: November 09, 2003
Posts: 1049
Location: Portland, OR
stevemariott is offline 

PostPosted: Fri Oct 22, 2021 8:40 pm    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Alstrup wrote:
I see several P heads on large engines these days because some ads show massive numbers with them. Iīm sorry to say, these heads are not off the shelf heads, they are up to heavily reworked. In stock form the P heads have outlived themselves at approx 2165 cc. more displacement than that and you loose upper end power and gain some lower rpm torque.

Alstrup,

I don't know, so I'm asking - how are those Panchito heads heavily reworked? Besides CNC chambers, I figured the CB dyno results would be with standard, off the shelf heads.
_________________
1963 Manx copy
1968 Bus
Back to top
View user's profile Send private message Gallery Classifieds Feedback
modok
Samba Member


Joined: October 30, 2009
Posts: 26743
Location: Colorado Springs
modok is offline 

PostPosted: Fri Oct 22, 2021 9:04 pm    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

well, from 0-.050" the 163 is very gentle, but at .200" it's pretty fast, and it does not dwell that long at full lift.....
And somehow that makes strong torque.....in a good way

And that's exactly what I was thinking of today.
This "question" is supposed to be about heads, but also PICKS at cams too.
The engine with the bigger heads SHOULD have a powerband 500 rpm higher, and SHOULD make more power, no matter if the cam is SLIGHTLY less...... 10 degrees of cam duration should be lesser factor, but, those darn examples just aren't right man!

I think a lot of people don't fully understand it.... including myself, I understand it a little but not fully.....but there are lets say "lobe shapes" that are very good at pumping up the midrange torque, and surprisingly good valve control at the same time.....
but they look lazy if you look at the numbers in the catalog.
That's a big problem is you have to BUy the cam to graph it out and see what it really is, and nobody has time to do that.
Even just looking at a big table of cam doctor numbers I have a hard time seeing what it all means, I have to draw it out and think about what the valve is doing too.

I know SOME cams are designed to lift at the maximum rate the lifter size allows, so they accelerate up this rate before .050 and stay there unitl it's 2/3-3/4 of the way open. This does give the most area with the lifter constraint, and actually might be best for high rpm, but that is not necessarily the best way to generate strong midrange torque or the best overall powerband, and definitely not the best valvetrain stability either.
But since I have not graphed out a 86a or a fk7 I don't know how the lobe shapes compare.

And of course it could be all lost of the rocker ratio or valve size is not right for it... but, general idea.... the way to trap air IN the engine is open the door wide to let the air in, then slam the door shut.
But what lift is open and what lift is closed? Maybe how long the door is more than half open is the real duration.... and we want the door to swing through half open at max possible velocity.... But what is "half open"? Maybe 0.15 x valve size?
That would be about the minimum valve lift that port velocity could be a thing IMO, valve curtain about .75% of the port area?
Isn't the bowl area much larger, yes, but that is taken care of....lets say the pump is already PRIMED, by the overlap flow, and for that to happen there does have to be enough overlap to let that flow occur....at high RPM it would be best to lift the valve from there at max rate, but for lower rpms maybe it isn't, max piston velocity does not happen for some time after overlap flow. Lift rate lagging here may hurt high rpm power but it might help midrange torque. Prime the pump with overlap flow, concentrate the flow in a tight window then slam the door.

And then I think we will see how to make some torque Wink
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Paul.H
Samba Member


Joined: April 03, 2015
Posts: 613
Location: England
Paul.H is offline 

PostPosted: Sat Oct 23, 2021 1:04 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Image may have been reduced in size. Click image to view fullscreen.


This is a 1904cc fitted with a Scat C35 cam, CB roundport CNC heads opened up to a small oval, merged header, 45mm straight manifolds,fuel injection 130hp. It'd still be going to over 7k.
Would you really want that in a bus ?
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Alstrup
Samba Member


Joined: July 12, 2007
Posts: 7183
Location: Videbaek Denmark
Alstrup is offline 

PostPosted: Sat Oct 23, 2021 2:29 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

The OP didnt say anything about a bus. - I brought that up in order to try and explain.
But the information in that collection of dyno pulls is actually quite usefull if you know what to look for. I will try and explain.
Just for the record. This is not! turning into a lets bash Paul type of thread. He had the guts to show the print, so lets give him credit for that. īWith a little luck he may even chime in with more information.

Now, 130 hp is by no means bad from a set up like that. If we begin to analyze at the power and torque curve (I love to do that Cool the first thing to notice is a really nice and clean powercurve. That is for a good deal due to the F.i. But it also shows that the relation between the intake and exhaust is fairly decent, maybe with a tad too much exhaust. (But that choice also depends on what the engine is to be used for)

With the power curve. Note how the power flattens out at about 5750 and holds the power there for about 500 rpm. That is a typical indication that the port volume is on the large side for the actual port flow. So the ramming effect canīt help the engine more than it does at 5750 rpm. The pump canīt pull more air through the valves under the given circumstances.

Another "giveaway" that the port volume is juust on the large side for the displacement is the difference between the torque curves. Note how the single 42 TB set up pull significantly more lower end torque. Thatīs due to the increased port velocity which again makes a better cylinder filling. Obviusly the single TB looses as rpm increases.

This engine is clearly set up for being fun to bash through the gears with decent every day driveability, and Iīm sure it does just that.

For comparison we can poull a dyno print that is in the performance engine build thread.
Image may have been reduced in size. Click image to view fullscreen.

This is a 1914 engine built for a buggy with big rear tyres. This engine was built for good lower rpm torque behaviure in order to pull the vehicle at only 2250 rpm @ 50 mph. So I chose ported stock valved heads with Honda guides, good valves, Oteva S75 springs, light valve train and a VZ 14 cam. 40 Dells on short manifolds and a regular 1―" baja/buggy exhaust w free flow muffler.
As you can see it peaks some 600 rpms earlier and immediately begins to fall off after that. Thatīs because the engine is basicly choking. The port canīt deliver more with the given area, or duration versus lift versus port vacum.
So basicly this is two sides of the same coin.

@ Steve. I hope Iīm not getting into trouble here, because it is a little controversial. There may be, and probably are variations to the cast P heads, but I have never seen a set of those actually support the claimed cfm numbers. The best of them are about 6 cfm off which means that in a max hp set up they will support about 165-170 hp on a good day. The reason to why the large displacement engines loose power compared to engines in the 2110-2165 cc sizes is exactly the same as we were talking about above. The ports do not have enough reserve volume so the air speed becomes too high too early and there is not enough "behind" so to speak to support the ramming at so relatively low rpm. Thatīs why we keep seeing 2110īs and 2165 engines pull very nice numbers and great overall torque, because there the heads "fits the glove" very well.
On the other hand. IF they are to be used on a larger displacement engine and you want it to pull numbers relatively equal to a 2165 you can come a long way with a Dremel and a couple of hours and open the intake ports at strategic places. But if you donīt know much about porting I suggest you leave them alone, because you can soon get yourself into trouble. Been there done that.

Dan, you lost me. What are you trying to say???

Modok. I donīt have much to add. Need to chew a little on that one Rolling Eyes Very Happy
_________________
https://www.thesamba.com/vw/forum/viewtopic.php?t=435993
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Paul.H
Samba Member


Joined: April 03, 2015
Posts: 613
Location: England
Paul.H is offline 

PostPosted: Sat Oct 23, 2021 2:54 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

You're reading too much into it . the bottom line is that the 285 degree cam is just too big unless you want a race car. I did take this motor over 7k and it didn't dip much. True camshaft characteristics are often masked by restrictive carbs, shitty exhausts and fan belts. There's nothing radical about the heads and it was a 1.5 header. Playing around with a multitude of cams all around the 285 duration is not going to deliver some magical mystery boost in torque or hp.
This test shows the comparison between the highest flowing intake to the lowest flowing intake
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Bad bug
Samba Member


Joined: March 11, 2006
Posts: 1119
Location: Jamaica
Bad bug is offline 

PostPosted: Sat Oct 23, 2021 6:20 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

For some reason i keep coming back to look at this 2276cc engine with 40 x 35.5 valves.

https://www.thesamba.com/vw/forum/viewtopic.php?t=265227&highlight=gerico+engine
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
txoval
Samba Member


Joined: January 23, 2004
Posts: 3540
Location: The Woodlands, TX
txoval is offline 

PostPosted: Sat Oct 23, 2021 7:47 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

First, this is a great thread and appreciate everyone participating.

Here are the characteristics of my Nowak Billet Cam, JN5 version

LC: 108
Cam lift: .394"
Total Duration: 312
Opening angle at .020": 296
Opening angle at .050": 258
Opening angle at .100": 226
Opening angle at .300": 120

Nowak calls this a "torque cam" for 40x35 valve heads, 1900-2100cc engines

I probably have simplified his description, but for those who understand cams better, why does this larger duration cam produce a lot of torque over the entire rpm range?

Yes, this is a very precise billet steel cam, which helps. My 2095cc engine can idle at 600 rpms with this cam (Dual 45 Dells)
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Brian_e
Samba Member


Joined: July 28, 2009
Posts: 3228
Location: Rapid City, SD
Brian_e is offline 

PostPosted: Sat Oct 23, 2021 7:55 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Keep it simple with good parts, that are correctly sized.

I feel this combo is about the perfect street 2276cc for a fun, easy, lasting engine. Really good 67ish cc port, 175+cfm 40x35 heads, Fk8/2288/86b, 1.4’s, 44’s, 9.5 w/.045 deck and a 1 5/8 header.

Lots of power everywhere, easy to drive, and no need to rev over 6200rpm.

With new fully machined aluminum cases, they go together almost like a stock engine.

Brian
_________________
www.type-emotorsports.com
Back to top
View user's profile Send private message Visit poster's website Facebook Instagram Gallery Classifieds Feedback
Paul.H
Samba Member


Joined: April 03, 2015
Posts: 613
Location: England
Paul.H is offline 

PostPosted: Sat Oct 23, 2021 10:39 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

txoval wrote:
First, this is a great thread and appreciate everyone participating.

Here are the characteristics of my Nowak Billet Cam, JN5 version

LC: 108
Cam lift: .394"
Total Duration: 312
Opening angle at .020": 296
Opening angle at .050": 258
Opening angle at .100": 226
Opening angle at .300": 120

Nowak calls this a "torque cam" for 40x35 valve heads, 1900-2100cc engines

I probably have simplified his description, but for those who understand cams better, why does this larger duration cam produce a lot of torque over the entire rpm range?

Yes, this is a very precise billet steel cam, which helps. My 2095cc engine can idle at 600 rpms with this cam (Dual 45 Dells)


I'd like to see a dyno graph for that motor if you have one. "torque cam" could mean anything and idles at 600rpm is good but doesn't give much away
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Alstrup
Samba Member


Joined: July 12, 2007
Posts: 7183
Location: Videbaek Denmark
Alstrup is offline 

PostPosted: Sat Oct 23, 2021 10:45 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Its reasonably simple, especially when you know Nowak cams in general Wink High duration low lift typically promotes that behaviure.
_________________
https://www.thesamba.com/vw/forum/viewtopic.php?t=435993
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Paul.H
Samba Member


Joined: April 03, 2015
Posts: 613
Location: England
Paul.H is offline 

PostPosted: Sat Oct 23, 2021 10:59 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Alstrup wrote:
Its reasonably simple, especially when you know Nowak cams in general Wink High duration low lift typically promotes that behaviure.

I never heard of him so I'd like to see a dyno graph. I'm one of those trust but verify kind of guys Wink
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Alstrup
Samba Member


Joined: July 12, 2007
Posts: 7183
Location: Videbaek Denmark
Alstrup is offline 

PostPosted: Sat Oct 23, 2021 11:14 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Really?
Heīs just on the other side of the channel.
https://frisiersalon-nowak.de/
_________________
https://www.thesamba.com/vw/forum/viewtopic.php?t=435993
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Paul.H
Samba Member


Joined: April 03, 2015
Posts: 613
Location: England
Paul.H is offline 

PostPosted: Sat Oct 23, 2021 11:24 am    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

Yes really I haven't. But you seem very familiar with the products so I guess you must use his products so do you have any dyno graphs ?
Obviously someone claiming all round torque on a 312 degree cam is pretty radical and would generate some questions
Back to top
View user's profile Send private message Gallery Classifieds Feedback
txoval
Samba Member


Joined: January 23, 2004
Posts: 3540
Location: The Woodlands, TX
txoval is offline 

PostPosted: Sat Oct 23, 2021 12:43 pm    Post subject: Re: Big valves/Hot Cam vs. Smaller valves/Hotter Cam Reply with quote

If I had a dyno graph I would post

Only reason I posted about idle is due to the total duration, that would normally be hard to achieve…granted my static CR is 9.8:1 and should have gone higher.

Cam comes on extremely hard above 2500rpms

Image may have been reduced in size. Click image to view fullscreen.
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> Performance/Engines/Transmissions All times are Mountain Standard Time/Pacific Daylight Savings Time
Page: Previous  1, 2, 3, 4  Next
Page 2 of 4

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2023, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB
Links to eBay or other vendor sites may be affiliate links where the site receives compensation.