Robert Posted July 1, 2009 Share Posted July 1, 2009 Hi, I got a L24E from a Nissan Laurel, 1987. This engine has dual valve springs. What is the maximum valve lift I can use on it? Standard valve lift is about .42 (A cam). Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted July 2, 2009 Administrators Share Posted July 2, 2009 For essentially any Stock cam, the stock springs are fine. If you plan to use an aftermarket cam with ANY more lift/duration than stock, the stock springs will are NOT adequate! Hope that helps. Quote Link to comment Share on other sites More sharing options...
Robert Posted July 2, 2009 Author Share Posted July 2, 2009 For essentially any Stock cam, the stock springs are fine. If you plan to use an aftermarket cam with ANY more lift/duration than stock, the stock springs will are NOT adequate! Hope that helps. In other words the stock, dual springs are crap? hehe:) Thats helpful.. The stock cam is said to be .413.. Im planing on using a .460, not an extreme upgrade.. Has anyone tried this? Does it result in valve float or what? Thanks Robert Quote Link to comment Share on other sites More sharing options...
theghosttanker Posted July 2, 2009 Share Posted July 2, 2009 The stock springs can handle up to .460 lift. If you go above that, they can coil bind. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted July 2, 2009 Administrators Share Posted July 2, 2009 The stock springs can handle up to .460 lift. If you go above that, they can coil bind. Coil bind is not the ONLY aspect that is to be looked at when evaluating springs that may be suitable for a particular cam! I have already written tons of info on this subject posted elsewhere on this forum so I wont be rehashing that again here. Just because they bind at .460" is not a reason to consider using them. Those sorts of comments are how some of the myths get started, something we don't want to perpetuate. Stock springs will NOT control the valve at the RPMS a .460" cam will allow the engine to rev to, PERIOD! If the stock springs are just adequate in controlling the valve, i.e. no valve float, for the .413†lift stock cam up to 6500 RPM, then rest assured a more aggressive cam will not be able to rev as high due to valve float setting in much sooner, which is backwards with a more aggressive cam as it will want to rev higher! You might get away with stock springs on a more aggressive cam, but only for a very short period, say 1000-10,000 miles on street car, then the springs will be worn out and in need of replacement. In short, just nut up and buy the correct springs! The valve train is NOT the area to be cutting corners, unless you like just throwing money away for no apparent reason! Quote Link to comment Share on other sites More sharing options...
Robert Posted July 3, 2009 Author Share Posted July 3, 2009 Looks like you know your stuff. Ive spoken to Schneider, they said pretty much the same thing. .430 was the max lift they would recomend.. Im thinking of buying one of their camshafts with .460 lift and 230240 duration at .050 on a fuel injected L24E.. Do you think my bottom end will suffer to much, and maybee the 220230 duration cam would be a better choise? Ever tried these cams? Or can the .430 version of the 220230 be a good option as well on the 2.4? Thanks Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 3, 2009 Share Posted July 3, 2009 The stock nissan computer will not handle an aftermarket cam very well...spend the money on a new injection computer first, then cam away. Just a little heads up; otherwise your new larger cam *may* run like crap. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted July 3, 2009 Administrators Share Posted July 3, 2009 The stock nissan computer will not handle an aftermarket cam very well...spend the money on a new injection computer first, then cam away. Just a little heads up; otherwise your new larger cam *may* run like crap. What he said, +1 Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 3, 2009 Share Posted July 3, 2009 Coil bind is not the ONLY aspect that is to be looked at when evaluating springs that may be suitable for a particular cam! I have already written tons of info on this subject posted elsewhere on this forum so I wont be rehashing that again here. Just because they bind at .460" is not a reason to consider using them. Those sorts of comments are how some of the myths get started, something we don't want to perpetuate. Stock springs will NOT control the valve at the RPMS a .460" cam will allow the engine to rev to, PERIOD! I got a myth for you. My first head was completely screwed by the machine shop I used. When I installed a .490 lift cam, they ran into coil bind. The machinist and my friend who built the engine got in a fight over how long it was taking, so the machinist took it out on my head. He CUT THE VALVES until they had no margin at all in order to get about .010" or .015" clearance from coil bind, and slapped the motor together. I ran it like that for a couple YEARS until the valves tuliped and started to leak, and then when I went to rebuild the head a new machinist found all the BS work that was done. With stock valve springs and .490 lift, that engine turned 7500+ rpm at one point on the track and only floated the valves maybe once or twice with it set up wrong like that. The problem is coil bind, not float in my experience. You need the aftermarket valve springs to allow more lift, not more rpms. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 3, 2009 Share Posted July 3, 2009 Oh, wait a minute, this an L24E... do those have the same valve springs? Can't remember, thinking they don't... Quote Link to comment Share on other sites More sharing options...
Robert Posted July 4, 2009 Author Share Posted July 4, 2009 What engine did you use? The springs are double, so I really want to try without new springs, but its to much work when everyone says they are crap.. Regarding the injection system, Ive got problems to see why it will have problems? There is a air flow meter in there, and the ecu simply multiplies CoolantairtempRPMS and air flow meter readings. Larger cams will make the air flow signal higher, and therefore add more fuel.. The ignition system is independent of the fuel system, and adjustable at the dizzy... So In my theoretical opinion, a new cam should be no problem. If any of you actually tried larger cams on a FI system, or know someone who did, please share your story though. Quote Link to comment Share on other sites More sharing options...
theghosttanker Posted July 4, 2009 Share Posted July 4, 2009 While we are relating "myths" vs "actual experience"... I ran a 460 lift cam on stock springs for 60K miles in an l-24 with no problems. It was a street car so in practice it was seeing only about 300 rpm's more than it did with the stock cam, and only in brief periods. I also lightened and balanced the rockers. So if you want to try it, I say go ahead. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted July 4, 2009 Administrators Share Posted July 4, 2009 Sorry Jon, I am not buying that the stock springs, even new ones, will hold 7500 RPM with a .490" lift cam! Not even for 1 lap without floating the valves, Sorry. The springs must have been something other than OE L6, such as the roadster outer springs, etc. Robert, Best of luck with your spring choices... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 4, 2009 Share Posted July 4, 2009 I KNOW, not guess, not think, but KNOW that they were stock valve springs. I had to replace them because they were coil bound when installed on new valves. The second machinist I used offered to testify if I decided to sue the first guy because the work he did was so bad (I didn't sue, BTW). The second machinist also verified the cam specs via a dial indicator just to make sure the cam that I had bought was indeed installed in the head, and made mention of how most cams that are spec'd at .490 don't actually come out right at .490 on the dial indicator but mine did. The 7500 rpm story: I had removed my MSD and thus the rev limiter once when I was starting to tune the Mikunis because I thought that the multiple sparks were making it impossible to read the plugs (turned out I just suck at reading plugs). Coming up the front straight at Streets of Willow I put a pass on my friend in his 510, looked down and was turning 7500 rpms (Autometer tach too, not stock innaccurate tach rpm "suggestion"). Experience > theory, and you can't possibly convince me that I didn't have this experience. They weren't new stock springs, they were 5/70 mfr date stock valve springs on the original E31 head, so about as old as they could possibly be too. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted July 4, 2009 Administrators Share Posted July 4, 2009 Jon, I have faith in that, you know what you are talking about. Your knowledge and experience with L-6’s is well documented. As such, I cannot argue against your testimony. All I can say is that my experience in this field does not support the experience you described. That is not to say it didn’t or couldn’t have happened, it just goes against conventional wisdom and I would not put faith or condone that spring/cam combination to anyone. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 4, 2009 Share Posted July 4, 2009 All I can say is that my experience in this field does not support the experience you described. That is not to say it didn’t or couldn’t have happened, it just goes against conventional wisdom and I would not put faith or condone that spring/cam combination to anyone. Agreed. It had to be really rigged just to get the parts in the head in the first place, which is why there was talk of suing the guy who did it. On a .460 cam though I'm not so sure there is an issue. Might be a little closer than ideal to coil bind, but you've got at least one other guy in this thread saying that it works. Quote Link to comment Share on other sites More sharing options...
Robert Posted July 5, 2009 Author Share Posted July 5, 2009 Well, Ive ordered new springs as well, I dont risk the hours of work if it goes wrong.. As noone had further inputs on the FI system, Im going to use it and see how it goes. The stock injectors should hold about 200hp @ less then 90% opening times (hopefully), so I think Im safe as long as the predictions made by some dont come true. Thanks For the inputs guys. Custom grind from Schneider with upgraded springs is on its way. By the way they can easily be recomended, great customer service and advice. Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 5, 2009 Share Posted July 5, 2009 Hopefully the cam won't screw up the fuel injection computer, but be warned. It's not the fueling requirements that the injectors can handle so much as the fueling calculations the ECU can handle. The ECU goes into a lookup-table mode above 4500 RPM, basically ignoring any input from the AFM. If your engine is pulling more air, then it will be going into lookup-table mode faster, and not getting enough fuel, since the computer is not even looking at how much air is really coming in. It just goes by a preset, non-changeable fuel curve. So you see, it's not as much an injector problem as it is a brain problem, the stock ECU is pretty dang primitive compared to the newer systems. Let us know how it works, there are some cams out there that can work well with the stock ECU, but the vast majority do not. Quote Link to comment Share on other sites More sharing options...
Robert Posted July 6, 2009 Author Share Posted July 6, 2009 Hopefully the cam won't screw up the fuel injection computer, but be warned. It's not the fueling requirements that the injectors can handle so much as the fueling calculations the ECU can handle. The ECU goes into a lookup-table mode above 4500 RPM, basically ignoring any input from the AFM. If your engine is pulling more air, then it will be going into lookup-table mode faster, and not getting enough fuel, since the computer is not even looking at how much air is really coming in. It just goes by a preset, non-changeable fuel curve. So you see, it's not as much an injector problem as it is a brain problem, the stock ECU is pretty dang primitive compared to the newer systems. Let us know how it works, there are some cams out there that can work well with the stock ECU, but the vast majority do not. Are you serious? Im not saying youre wrong or anything, but Im just curious why the engine feels good at all throttle positions If all above 4500RPM has locked duty cycles on the injectors? There is no TPS sensor here (Its a switch on zero and full throttle). Can you document this somehow? Ive serched the internet, but found no specific info on the FI system.. I do have a workshop manual though, and Ill have a look in it. Hopefully it will give some more detailed info. Keep in mind though, this is a 1987 model L24E, not from a old Z.... If I find no good info, Ill fin a scoop and measure the injectors at over 4500RPMs. If the duty cycle changes at different throttle positions, the AFM is in the calculation. If they dont.. Well then my eyes will pop out of my head, cause I really have bigger thoughts for Nissan.. And Im not megasquirting this engine to run a 200hp NA engine, I got a L24E turbo engine about to fire up, the only reason I want to get a new camshaft is that my cylinder head needs a overhaul... Thanks Robert Quote Link to comment Share on other sites More sharing options...
daniel86 Posted July 6, 2009 Share Posted July 6, 2009 Thanks for the information great post. Quote Link to comment Share on other sites More sharing options...
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