S130Z Posted November 21, 2009 Share Posted November 21, 2009 So I came up with this idea the other night for a DOHC double cross flow cylinder head(DCFCH:icon45:). My idea was to have a DOHC head where you have an intake and exhaust valve on each side of the cylinder. This could possibly yeild you two advantages. One being to cross the intake valves to create a swirling effect for a more dense charge. The other advantage would be having two intake manifolds. You can potentially have a different sized runner on each side, one for torque and one side for HP. And sice you would have an intake and exhaust valve per side, you can have two different cam profiles. One profle for torque and one profile for HP. The throttling would need to be different per manifold also. The torque side manifold would need to open first and then have them both open in your upper RPM's. (Here is my paint picture I drew as a reference) Quote Link to comment Share on other sites More sharing options...
S130Z Posted November 21, 2009 Author Share Posted November 21, 2009 As I continue to ponder on this idea, I come to think of a turbocharged version. On the torque side of the head, run low boost on a small hot side for a quick spool time. On the HP side of the motor, run high flow/boost and a larger hot side for your top end. Since your two intake manifolds are not connected, this eliminates crossing air flow and pressure from the two turbos. You would also run twice the injectors giving you a greater ability to tune the engine. It's almost like running two completely different cylinder head and intake setups at the same time, just timed differently throughout your RPM's. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted November 21, 2009 Administrators Share Posted November 21, 2009 Interesting… do you mind if we input, discuss, etc? I love these sort of discussions.. I like the concept as seen from the piston for the swirl concept. Keep the valves angled to keep the flow “into†the chamber at an angle forcing the vortex. Manufacturing/casting would be quite complex with those ports above the chamber with coolant passages surrounding as much of the chamber as possible. Having twice the induction plumbing and exhaust plumbing could definitely offer some very intricate and aesthetically pleasing bundle of snakes on either side of the valve cover/s. Quote Link to comment Share on other sites More sharing options...
S130Z Posted November 21, 2009 Author Share Posted November 21, 2009 Thanks for the input Paul. Everyone, please feel free to input. We don't really have to get into the cooling and production specs on this because as of now it's pure speculation and theory. And as for the exhaust note for an N/A version......the two slightly different frequencies...(you know where I'm going with this). It may create a "beat frequency", where two similar frequencies cross and create a "vibration" effect. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 23, 2009 Share Posted November 23, 2009 Why would you need two manifolds on opposite sides of the head? A manifold with equalization runners to make up for differences in the in-head portion of the port would allow this design to function without double manifolds. Kind of like the 'inline V-6' VW makes now... Quote Link to comment Share on other sites More sharing options...
johnc Posted November 23, 2009 Share Posted November 23, 2009 IMHO, the added weight of the complex intake and exhaust plumbing would likely negate any horsepower or torque benefits. Fun to build and look at but no faster on the street or the track. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted November 23, 2009 Share Posted November 23, 2009 John beat me to it. More weight.. more parts and greater complexity.. which means more parts to fail or something to go wrong. Quote Link to comment Share on other sites More sharing options...
evil_datto Posted November 23, 2009 Share Posted November 23, 2009 V8 has two exhaust manifold, one intake manifold. If this were say an L6 with this idea, it would be two exhaust, two intake. I don't see how that one extra intake (compared to V8) is going to negate anything at all? & "More weight.. more parts and greater complexity.. which means more parts to fail or something to go wrong." It's just the same as a DOHC head, only with 2x intake/exhaust ports... You'd have the extra intake manifold, 2x injectors (no problem there if it's megasquirt) 2x TB's... http://carphotos.cardomain.com/ride_images/1/2656/461/6637730029_large.jpg 300zx's don't seem to have a problem with two intake, tb, (i think some people even use dual map sensors)? Am I just missing something? Quote Link to comment Share on other sites More sharing options...
johnc Posted November 23, 2009 Share Posted November 23, 2009 Am I just missing something? Yes, I think we're talking about a straight 6 engine per the picture in the first post. I'm not comparing this double cross flow design to a V8 engine because that's a completely different topic. Quote Link to comment Share on other sites More sharing options...
evil_datto Posted November 23, 2009 Share Posted November 23, 2009 An intake & another set of headers don't weight that much & isn't that much more complex than a V engine (Look at the picture I linked to, 300zx pulled it off with twin turbos... even more complex intake). I'm still not seeing your point Quote Link to comment Share on other sites More sharing options...
johnc Posted November 23, 2009 Share Posted November 23, 2009 OK, my point is: The additional weight of the second intake manifold, exhaust header, and related plumbing (probably 40 lbs total) will offset any unproven horsepower gains by the this double crossflow design over a regular crossflow cylinder head. Quote Link to comment Share on other sites More sharing options...
S130Z Posted November 23, 2009 Author Share Posted November 23, 2009 Thanks for all the input! JohnC you have a good point about the weight. The main subject I really wanted to get at was the ability of having two different profiled cams. It would almost be like having 2 motors in one(not power wise, but having 2 power "ranges"). Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted November 24, 2009 Share Posted November 24, 2009 very artistic !!! wow lol Quote Link to comment Share on other sites More sharing options...
Comrade_Charlie Posted November 24, 2009 Share Posted November 24, 2009 I like the idea, but if someone merely made a production dohc head for the l28 it would be popular, why try to make this instead, maybe your not trying to make it and just trying to think of something new, i dont know. I like it, cool. Quote Link to comment Share on other sites More sharing options...
Nizm0Zed Posted November 24, 2009 Share Posted November 24, 2009 Very interesting concept, but yea, potentially heavy. If i were to design something from scratch (even if its just a scratch built head for a certain straight 6) I would probably spend more time in trying to encompass 'proven' ideas straight from top level motorsports type motors. That or try to find a way to control airflow in and out of the cylinder that doesnt have a restrictive valve head in the way... Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 24, 2009 Share Posted November 24, 2009 OK, I'll just come out an SAY IT: the reason I mentioned VW's "Inline V" was because you would be able to make a 15 degree V12 that LOOKED like an inline six, and had the unequal length runners and all the complexities inherent in a design similar to that originally proposed. Save that at least then you will have 12 cylinders in the space of six... If you're going to make things complex, get something out of it! Like double the cylinders in the same longitudinal space...and not much more width-wise (not much more wider than a DOHC Head...) Quote Link to comment Share on other sites More sharing options...
S130Z Posted November 24, 2009 Author Share Posted November 24, 2009 Although you shot me down again Tony D, you have a good point. The overall potential of the engine would not be too much better than a standard DOHC. Quote Link to comment Share on other sites More sharing options...
TimZ Posted November 24, 2009 Share Posted November 24, 2009 OK, I'll just come out an SAY IT: the reason I mentioned VW's "Inline V" was because you would be able to make a 15 degree V12 that LOOKED like an inline six, and had the unequal length runners and all the complexities inherent in a design similar to that originally proposed. Save that at least then you will have 12 cylinders in the space of six... If you're going to make things complex, get something out of it! Like double the cylinders in the same longitudinal space...and not much more width-wise (not much more wider than a DOHC Head...) ...And of course VW already did something along these lines by arranging two VR6's in a conventional "V" to make a W12 that takes up roughly the space of a V8, in case anybody wanted to talk about something that you could actually put your hands on... Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 24, 2009 Share Posted November 24, 2009 That's where I was heading, TimZ! That's where I was heading... Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted December 2, 2009 Share Posted December 2, 2009 Have you guys seen Colt Cams' staggered lobe profiles for the 'swirl effect'? Swirl effect for fuel mixture is nice with DI. Why not figure a way to use direct air injection as well? Operate a compressor off of the relatively underutilized alternator electrical supply and inject air as well as fuel. Skip the inlet plumbing altogether. You'd want a high flow, low pressure compressor. Quote Link to comment Share on other sites More sharing options...
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