datsun40146 Posted December 8, 2007 Share Posted December 8, 2007 Ok, so I was watching the new season of Top Gear where they featured a Triumph/ British Leyland Sprint. Well what took me by surprise was the fact that it had 4 valves per cylinder but only one cam and its power output. I was wondering how this worked and if mabye it had a modern application. The motor that British Leyland placed that head on was a 2 liter four cylinder that made 127 bhp, which I though was VERY impressive for 1973. I was thought I would ask what everyone thought about that head design. This is what I've been able to find with a quick google search. Thanks Once the logical decision was taken to use the slant-four engine. The development of the slant-four would provide the perfect engine to compete more effectively in motor sport. Spen King devised a plan to extract more power. With co-operation from Harry Mundy and the engineers at Coventry Climax, a 16 Valve cylinder head was designed, which would sit atop a two-litre version of the engine. Ingeniously, the 16 Valves would be actuated by a single camshaft, long rockers across the head were used to actuate the second bank of valves. The arrangement was clever because it negated the need for an expensive twin camshaft arrangement, and would offer all the benefits of the multi-valve layout. At a stroke, Triumph had developed an engine that would power the marque's cars in a most effective way for many years to come - certainly, the SD2 was conceived with a fuel-injected version of this engine very much in mind. Development posed interesting problems, simply because of the fact that the 16V slant-four was so efficient, it was relatively easy for the engineers to tweak it to produce over 150bhp. The final figure was 127bhp - a very healthy figure, especially when viewed in the context of its 1973 introduction. Like the Dolomite before it, the Sprint (the name chosen early on during development) was subject to several delays - but it duly appeared in the autumn of 1973, and was greeted by buyer and press enthusiasm, alike. Quote Link to comment Share on other sites More sharing options...
Vintage Posted December 8, 2007 Share Posted December 8, 2007 It's not exactly a new concept anymore. I've rebuilt a 1.6L Honda SOHC with 4 valves per cylinder. Quote Link to comment Share on other sites More sharing options...
280Z Turbo Posted December 8, 2007 Share Posted December 8, 2007 Yep, I know the Honda D16A6 has that setup. The Chrysler 3.5L V6s are also like this, IIRC. Quote Link to comment Share on other sites More sharing options...
Careless Posted December 8, 2007 Share Posted December 8, 2007 I think Honda did that with the 1.5L D15 engines and the 1.6L D16 engines early on, like in 1984, all the way up to 2000 for the rest of the D series... i think.... Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted December 8, 2007 Share Posted December 8, 2007 lots of inline 4 motorcycles are that way. Quote Link to comment Share on other sites More sharing options...
datsun40146 Posted December 8, 2007 Author Share Posted December 8, 2007 Does anyone have any diagrams or pictures or anything that can help me understand how this works. Thats really what I'm after. Thanks Quote Link to comment Share on other sites More sharing options...
Kennysgreen280zt Posted December 8, 2007 Share Posted December 8, 2007 im sure there is either a single rocker to hit two valves, or two extra lobes and rockers per cyl. I cant seem to find any pics in a quick google search. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted December 8, 2007 Share Posted December 8, 2007 i know on bikes its been done both ways.. either picture a rocker arm that has one follower on the cam and then splits into a Y after the pivotand pushes on 2 valves and then the cam is inbetween the intake and exhaust valves so one side has the exhaust and one side has the intake with 2 y shaped rocker arms. if you ever run into this set up and are adjusting valves you have to have 2 sets of feeler gauges so you can measure the clearances of both rocker arms at the same time as to not cock the rocker arm up on one side. Quote Link to comment Share on other sites More sharing options...
Vintage Posted December 8, 2007 Share Posted December 8, 2007 The D16 I did had two extra lobes/rockers per cylinder like Kenny suggested, I'm pretty sure. Quote Link to comment Share on other sites More sharing options...
Careless Posted December 8, 2007 Share Posted December 8, 2007 Quote Link to comment Share on other sites More sharing options...
Challenger Posted December 10, 2007 Share Posted December 10, 2007 My Crf250r had the Unicam head which was a single cam with three lobes. The outsides activated the intake valves which were directly below it and the middle lobe lifted a rocker that split to activate the two intakes. I liked it because it was easy to adjust and if you buy a performance cam, its only one. Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted December 10, 2007 Share Posted December 10, 2007 There's a really sick VW bug that has a set of 16v heads that still run 8 pushrods and a single cam http://www.araoengineering.com/VWheads.htm 4400 bucks for a pair, a bit steep considering a lot of people have that much in just the engine. The car they have featured on the site is nice though. runs a custom built air/air intercooler, twin turbo, and 4 single barrel mikuni's Quote Link to comment Share on other sites More sharing options...
IdfMF Posted December 10, 2007 Share Posted December 10, 2007 There were SOHC 16 valve heads made for the Ford Model T in the late 'Teens through late 1920's. A company called Craig-Hunt made one of the more well known heads. Nothin' new under Sun! Tom Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted December 10, 2007 Share Posted December 10, 2007 I know the dodge/plymouth neon had one too... Mario Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 10, 2007 Share Posted December 10, 2007 32 valve pushrod heads have been available for SB Chevies for years. Detroit Diesels ran a four valve head with bridged valves off pushrods, and that was a two stroke! LOL Quote Link to comment Share on other sites More sharing options...
Michael Posted December 17, 2007 Share Posted December 17, 2007 I used to have a 1990 Toyota Corolla with “16 valves†stamped on the rocker cover, but I’m pretty sure that it was SOHC. Quote Link to comment Share on other sites More sharing options...
Hyuri Posted December 17, 2007 Share Posted December 17, 2007 I used to have a 1990 Toyota Corolla with “16 valves†stamped on the rocker cover, but I’m pretty sure that it was SOHC. The only engine options I'm aware of for US-spec E9x Corollas were 4A-F(E) and 4A-GE, all of which were DOHC. You may be confused by the fact that the 4A-F motors had a single cam sprocket: the intake cam was driven by the exhaust cam via internal gears (picture towards the bottom here). The 4A, 4A-C, and 4A-E were SOHC, but only had 8 valves. Quote Link to comment Share on other sites More sharing options...
yenghua Posted January 8, 2008 Share Posted January 8, 2008 if you go to howstuffworks.com you'll find very usefull information there... Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 8, 2008 Share Posted January 8, 2008 Arao makes 4 valve heads that use 1 cam, in a V-configuration. http://www.araoengineering.com/LSX.htm Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted January 11, 2008 Share Posted January 11, 2008 WHOA i didn't know Arao made heads for V-8's I posted their page on their VW heads earlier XP Quote Link to comment Share on other sites More sharing options...
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