Guest Terry S Posted March 10, 2004 Share Posted March 10, 2004 AFAIK the heads are identical except the cams. The cars were designed for different things. The JDM car is a quick street racer, hence it has smaller turbo AR's and less lift on the inlet cam, all leading to quicker turbo spool, whilst the export versions were designed more a long distance GT cars. You have to decided whether you really need massive lift on the inlet. These cars make huge power on 256 inlets. You will just be increasing lag by using a 272 inlet. Yes you will make slightly more power, but peak power really isn't the issue with these cars, as most can't get traction anyway. rant over.... Quote Link to comment Share on other sites More sharing options...
Wez Posted March 10, 2004 Share Posted March 10, 2004 Cool post So how about 256/264 or 264/272? Would you share what you have gone for in your setup? Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted March 10, 2004 Share Posted March 10, 2004 Wez I have 256/264 Quote Link to comment Share on other sites More sharing options...
Wez Posted March 10, 2004 Share Posted March 10, 2004 Why does less lift and duration on the inlet help turbo spool? Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted March 10, 2004 Share Posted March 10, 2004 We are hijacking this. E-mail me [email protected] Quote Link to comment Share on other sites More sharing options...
Wez Posted March 10, 2004 Share Posted March 10, 2004 Sorry guys. Quote Link to comment Share on other sites More sharing options...
eyefi Posted March 10, 2004 Share Posted March 10, 2004 dont make it private Quote Link to comment Share on other sites More sharing options...
CJ Posted March 10, 2004 Share Posted March 10, 2004 I am suer that fastisnice is happy to hear the comments and doesnt consider it to be a thread hijack. This is good stuff! Quote Link to comment Share on other sites More sharing options...
Sharpie Posted March 10, 2004 Share Posted March 10, 2004 Yes, please keep going Quote Link to comment Share on other sites More sharing options...
Barry Posted March 10, 2004 Share Posted March 10, 2004 Yeah, this is a great thread. Just took this from to4r.com, talking about modifying the cylinder head. http://www.to4r.com/techcylinderhead.html " This is not simple or easy with the 2JZ-GTE. The stock exhaust ports fail to flow any more air at about 8mm of lift (0.317"). Increasing high lift flow is the first thing on the mind of the man holding the die grinder. Still there is not a lot to be gained. For these reasons, staggered cam sizes seem to work well in the Supra. A longer duration exhaust cam combined with a shorter duration intake cam can yield surprising results. Never forget, your cams must compliment the engine. Part of that is recognizing that valve lift over 8mm on the exhaust only promotes valve spring failure. For that reason, I don't recommend exceeding stock lift on the exhaust side. There is no advantage except in the driver's mind." Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted March 10, 2004 Share Posted March 10, 2004 Very basically it's down to the engines ability to swallow air at a given RPM. Cams are always a compromise. A 256 will be more efficient than a 264 at a lower rpm and visa versa. If you are using a big turbo then higher than stock RPM and higher lift cams make perfect sense. Because cam profiles are always a compromise, Manufactures developed VVTi type systems to try and minimise this compromise, so the valve timing alters and different RPM. Quote Link to comment Share on other sites More sharing options...
Digsy Posted March 10, 2004 Share Posted March 10, 2004 Darren blathers on about camshafts here. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted March 10, 2004 Share Posted March 10, 2004 So Darren, how far are Lotus away from Solenoid controled valves eh;) I wonder how long before the produce a fast enough one for use, and how much longer before it gets down to Joe Public, 10, 20 years?.............................It's nice to dream Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 10, 2004 Share Posted March 10, 2004 The poppet valve engine is really an abortion, it suceeds like the Porsche 911, by an excess of development over design. Given no emissions regs and a government not financing wasters through fuel tax, and hence cheap fuel, we might actually be driving behind modern and exciting engine developments Quote Link to comment Share on other sites More sharing options...
Digsy Posted March 10, 2004 Share Posted March 10, 2004 Originally posted by Terry S So Darren, how far are Lotus away from Solenoid controled valves eh;) I wonder how long before the produce a fast enough one for use, and how much longer before it gets down to Joe Public, 10, 20 years?.............................It's nice to dream We did this press release back in July last year. You'll just have to guess at how much further along we are since then Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted March 10, 2004 Share Posted March 10, 2004 Sounds promising, although it seems to have been muted for years. Quote Link to comment Share on other sites More sharing options...
Digsy Posted March 10, 2004 Share Posted March 10, 2004 We've had a rig running for probably a decade, and we regularly sell AVT setups to the major OEMs for development purposes. Its only recently that there's been a big push to make a system that can work inside an actual car. Hey - I get to use this -> Quote Link to comment Share on other sites More sharing options...
Supragal Posted March 10, 2004 Share Posted March 10, 2004 256/264. I believe this keeps the staggering near to stock. Toyota made it like that for a reason... Quote Link to comment Share on other sites More sharing options...
jagman Posted March 10, 2004 Share Posted March 10, 2004 lotus avt "new"technology, I had this idea 28 years ago ,did all the calcs/ drawings and submitted to about 12 different manufacturers,no interest except from ford who wanted a working model, like i had the cash/time?-solenoid valves will work to a point where reversing the magnetic fields so fast causes the valves to just stop,the answer is to pass a rotating field over the solenoids,not rotating the field in the solenoids,also the magnets very high temp magnets as used in development jet enginebearings,valve lift can then be infinitly variable,as can duration,result no cam required,no belts ,chains,no valve springs,rev limit is when the piston melts,timing controlled off a phonic probe on flywheel at tdc, an oddity is the starter motor needs to be 2 speed, firstly to crank the engine to tdc slowly, at which point the valve solenoids are "aligned",then the starter cranks normally,theres more- ask lotus to ring me - they didnt last time -tossers Quote Link to comment Share on other sites More sharing options...
Gaz Walker Posted March 10, 2004 Share Posted March 10, 2004 Originally posted by jagman theres more- ask lotus to ring me - they didnt last time -tossers Top notch Quote Link to comment Share on other sites More sharing options...
jagman Posted March 10, 2004 Share Posted March 10, 2004 sorry , hit a sore point there ,i spent 6 months designing the electrical camshaft in the 70s,a lot of work with no internet/faxes,etc, still got the drawings in the loft,being patriotic i tried all the british car manufacturers,only ford (u.s)responded,leyland too busy with that cutting edge design the austin princess! the one shaped like a door wedge.didnt that do well Quote Link to comment Share on other sites More sharing options...
dude Posted March 10, 2004 Share Posted March 10, 2004 Sounds like Lotus should give you a job and a large chunk of cash to me !!!! Dude:flame Dev Quote Link to comment Share on other sites More sharing options...
Digsy Posted March 11, 2004 Share Posted March 11, 2004 Originally posted by jagman solenoid valves will work to a point where reversing the magnetic fields so fast causes the valves to just stop,the answer is to pass a rotating field over the solenoids,not rotating the field in the solenoids,also the magnets very high temp magnets as used in development jet enginebearings,valve lift can then be infinitly variable,as can duration,result no cam required,no belts ,chains,no valve springs,rev limit is when the piston melts,timing controlled off a phonic probe on flywheel at tdc, an oddity is the starter motor needs to be 2 speed, firstly to crank the engine to tdc slowly, at which point the valve solenoids are "aligned",then the starter cranks normally,theres more- ask lotus to ring me - they didnt last time -tossers I guess I'm supposed to get drawn into an argument here? Well for pretty obvious reasons I'm not going to. I'm not denying that you may have thought of this first, but As you can read here our public-domain AVT development rig doesn't use any of the technologies you mention and neither, as far as I am aware, does the new in-car system. All the major OEMs are looking into this big style now, so you may find they are more interested if you write to them again. Quote Link to comment Share on other sites More sharing options...
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