Administrators BRAAP Posted January 13, 2010 Administrators Share Posted January 13, 2010 Overhead cam and multi valve heads used on traditional domestic V-8s! Seems like an interesting topic of discussion, yet not seen on this forum with any sort of depth or seriousness that aI was able to uncover. I recently stumbled across a pic of the Moser SBC DOHC heads and like the younger generation of today, was immediately distracted and dropped everything else I supposed to be doing at the moment to dig little deeper, for no other reason than curiosity… In searching this forum I would’ve bet money this topic had been covered to some degree in the past but couldn’t find anything with any real substance. (Possibly my search techniques genuinely suck, which I’m sure someone will exploit...) I'll start out with the probably the most well known of aftermarket offered traditional V-8 OHC heads, the Moser/Harvey Crane Jr, DOHC heads! DOHC cam, 4 valves per cylinder heads for the SBC short block. Dyno tested to as much as 11,000 RPM back in 1970! Mr Richard Moser bio; http://richardmoser.com/ Harvey Crane Jr, was instrumental in the development of these heads; http://www.harveycrane.com/moser.htm The HotRod magazine article, 4 pages worth; http://www.cadvision.com/blanchas/54pontiac/ChevyEngines.html Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 13, 2010 Author Administrators Share Posted January 13, 2010 Next up, I stumbled across this very interesting concoction using the vintage small journal SBC 265, (road draft crank case breather system). Has all the appearance of DIY from a small shop/garage. Like it! Note the cool cam oiling. Anyone, (TonyD,) have any info/history on this set up? Possibly some old school Bonneville or drag race effort? Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 13, 2010 Share Posted January 13, 2010 I am getting wood over the vintage engine. Oooooh so badly it is desired... The Moser is neat, but not in the same way the second one is! My preference runs to Schubeck's DOHC Efforts. If you see it, you will see why. http://www.schubeckracing.com/new2/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=12&MMN_position=52:52 (Secret) Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 13, 2010 Author Administrators Share Posted January 13, 2010 (edited) Tony has a bent towards Fuel Injected, Quad cam, huge by large displacement V-8's 904 C.I.D. anybody?... Twin plug D.I.S. Blown version.. Edited January 14, 2010 by BRAAP Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 14, 2010 Share Posted January 14, 2010 Look under the valve cover on the link I gave. Look closely... Muahahahahaha! Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 14, 2010 Author Administrators Share Posted January 14, 2010 (edited) Look under the valve cover on the link I gave. Look closely... Muahahahahaha! Rocker actuated valves vs direct actuation? Pseudo hydraulic-mechanical lash adjustment system, hydraulic lifters adjusted with a .002" clearance for NO lifter preload, effectively eliminating any lifter pump up at elevated RPM's? Edited January 14, 2010 by BRAAP Quote Link to comment Share on other sites More sharing options...
letitsnow Posted January 14, 2010 Share Posted January 14, 2010 http://www.aardemasohc.net/index_files/Page313.htm I've also heard that vh or vk heads are rather similar dimensionally to a SBC head. Here is a thread about it. http://turbo-infiniti.org/viewtopic.php?t=789&sid=bba4c0708a4356d9b337e6cb2c951435 Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted January 14, 2010 Share Posted January 14, 2010 Yup, happy time in my pants after seeing that. Quote Link to comment Share on other sites More sharing options...
Michael Posted January 14, 2010 Share Posted January 14, 2010 Are these "just" DOHC, or do they use some form of variable-valve timing? One suspects that the better modern aftermarket conventional-style OHV heads outflow most of the 4-valve DOHC exotics. And the engine rpm is probably more limited by bottom-end stability than by the valvetrain. Maybe 4-valves offer mid-lift flow advantages because the valve curtain area is larger for the same valve lift? Do 4-valve heads have a combustion chamber advantages over canted-valve 2-valve chambers? On a related note, what about multi-valve cam-in-block schemes? The advantage is short timing chain, compact design, no need to disturb the timing chain when removing the heads... but lower valve mass and possible combustion chamber advantages. Quote Link to comment Share on other sites More sharing options...
jbk240z Posted January 14, 2010 Share Posted January 14, 2010 I remember hearing about these OHC kits for the SBC a few years back. Very interesting, check out this link...http://www.aardemasohc.net/index_files/Page313.htm Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted January 14, 2010 Share Posted January 14, 2010 a really well designed and properly manufactured 4 valve single or double overhead cam head could easily boost the hp potential of the chevy v8 engines a great deal. http://www.billzilla.org/2v4v.htm http://www.gofastnews.com/board/technical-articles/281-polyquad-new-four-valve-power-concept.html http://www.araoengineering.com/Chevy/chevybb.htm bbc 2: 1.84 In. valves BB Chevy Intake Ports BB 32v. 2: 1.840 IN. valves Pontiac Pro Stock 2.38 In. valve 0.1 94.4 0.1 70.8 0.2 206.5 0.2 147.5 0.3 312.7 0.3 230.1 0.4 375.24 0.4 277.3 0.5 448.4 0.5 342.2 0.6 472 0.6 395.3 0.7 494.42 0.7 436.6 0.8 494.42 0.8 448.4 2: 1.6 Ex. valves BB Chevy Exhaust Ports BB 32v. 2: !.6 EX. valves Pontiac Pro Stock ! o Stock 1.9 Ex. valve 0.1 88.5 0.1 59 0.2 182.9 0.2 118 0.3 259.6 0.3 182.9 0.4 318.6 0.4 241.9 0.5 381.14 0.5 300.9 0.6 424.8 0.6 330.4 0.7 430.7 0.7 342.2 0.8 430.7 0.8 344.56 SBC http://en.wikipedia.org/wiki/Overhead_camshaft http://www.merkurencyclopedia.com/Motor/4valve_cylinder_head.html http://xlforum.net/vbportal/forums/showthread.php?p=2263412 http://books.google.com/books?id=mm8oM7_OuDEC&pg=PA7&lpg=PA7&dq=david+vizards+4+valve+head+design&source=bl&ots=nno2iRy8DI&sig=cHm0DtrqK8kPuoMtlkUYoDZKKFc&hl=en&ei=jJYrS8bmD4uRtgffl-mICQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAgQ6AEwAA#v=onepage&q=&f=false Quote Link to comment Share on other sites More sharing options...
Daeron Posted January 17, 2010 Share Posted January 17, 2010 Look under the valve cover on the link I gave. Look closely... Muahahahahaha! Rocker actuated valves vs direct actuation?Pseudo hydraulic-mechanical lash adjustment system, hydraulic lifters adjusted with a .002" clearance for NO lifter preload, effectively eliminating any lifter pump up at elevated RPM's? The most mind-bogglingly supercool mega-awesome awesome awesome thing *I* saw about that engine was the cam drive/timing system as compared to the accessory drive system. I cannot ruin it for you; you have to go back and look yourself. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted January 17, 2010 Share Posted January 17, 2010 Something along the same lines: Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted January 18, 2010 Share Posted January 18, 2010 Something along the same lines: And they've only been promised for how long now? Quote Link to comment Share on other sites More sharing options...
rsicard Posted January 19, 2010 Share Posted January 19, 2010 What is the technical advantage of double overhead cam engines? The newest corvette engine gets very good power with a Gen IV pushrod engine. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 19, 2010 Author Administrators Share Posted January 19, 2010 (edited) What is the technical advantage of double overhead cam engines? The newest corvette engine gets very good power with a Gen IV pushrod engine. In the most basic sense, SOHC vs the in block design of a 2 valve head, advantages of OHC is more direct valve actuation with the possibilty of lighter weight valve train, at least as seen by the cam lobe. Disadvantages are, for a V- engine, is the added overall wieght of an additional camshaft or 3 depending if it is SOHC or DOHC design, overal CG of the engine is higher with the cams being up on top of the engine, and common designs are taller and most of the time wider making the overall powerplant package physically larger, (modern Ford OHC V-8's are a good example of this). Outside of that within the 2 valve constraints, OHC advantges are not very large and also carry just as many not large disadvantages as well. As you pointed out, GM is still succesfully employing the single in block push rod 2 valve design in some of the worlds most powerful and best performing cars in the world, Vette Z-06 and ZR-1. Where OHC really starts to shine is when utilizing multi valve technology vs the 2 valve. Valve area per CID is much greater allowing for greater breathing, (combustion chamber roof is more vale than head material allowing the cylinder to breathe easier with less aggressive cam timng vs a comparable 2 valve design). Now with seperate intake and exhaust cams, fine tuning of the intake valve timing independant of the exhaust valve timing can be accomplished, and add to that real time variable cam phasing of the seperate cams, a very broad power band can be had while maintaining decent economy and mileage. Edited January 19, 2010 by BRAAP Quote Link to comment Share on other sites More sharing options...
MAG58 Posted January 19, 2010 Share Posted January 19, 2010 I'd like to have a set of those Arao heads! I think that there is much room left in developing multivalve, pushrod engines. They flow quite a bit more on the top end, and the force of having to move the pushrod and rocker, etc back on a valve closing event would be shared over two separate sets of valve springs meaning that the valve spring tension wouldn't have to be so astronomical and they could rev higher! Quote Link to comment Share on other sites More sharing options...
AkumaNoZeta Posted January 19, 2010 Share Posted January 19, 2010 Something along the same lines: What's this? Is it valve-less? Looks very interesting. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 19, 2010 Author Administrators Share Posted January 19, 2010 (edited) What's this? Is it valve-less? Looks very interesting. Rotary valves! http://www.coatesengine.com/ Edited January 19, 2010 by BRAAP Quote Link to comment Share on other sites More sharing options...
mutantZ Posted January 19, 2010 Share Posted January 19, 2010 Is there an inherent draw back to the rotary valve design? I've heard of these for years but never really seen a mainstream application. I'm afraid I'll be swapping an 11 turn triple into my electric car before these come out. Quote Link to comment Share on other sites More sharing options...
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