mikeyE Posted August 28, 2008 Share Posted August 28, 2008 my situation: i just purchased a 74 260z, i just found out its got an l28 ( which im slowly learning is a good thing) but the tach in the car says redline is 7000 all the info online says 7000 but my car feels like it maxes out at 6000 all tho i have not tried pushing 7000. i was wondering if im just babying the power of a l28 or if i have a mechanical problum under my hood. its carburated not fuel injected (dual carbs) any info will help Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted August 28, 2008 Share Posted August 28, 2008 my situation: i just purchased a 74 260z, i just found out its got an l28 ( which im slowly learning is a good thing) but the tach in the car says redline is 7000 all the info online says 7000 but my car feels like it maxes out at 6000 all tho i have not tried pushing 7000. i was wondering if im just babying the power of a l28 or if i have a mechanical problum under my hood. its carburated not fuel injected (dual carbs) any info will help The carbs may not be sync'd quite right. My old carbs were damaged and I never could sync them properly. I'd lose power completely at 5200, and the engine hesitated at 5600. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 28, 2008 Share Posted August 28, 2008 The camshaft profile on the L28 is less agressive than on the L26 or L24...or even the L20A. It will have peak power around 5300 rpms, and shifting above 6300 is pretty much a waste of effort, especially after the first two gears. If you have a different camshaft that is designed for higher rpms, the L28 will rev up slightly higher and still make power. But it's a limitation of the cap profile. You won't get much more revving from it, stock. Cast pistons limit the terminal speed of the engine to 7K for longevity reasons should you get radical ideas about a camshaft that pulls to 8500 so you can bury your tach... Our Bonneville LSR has an L28 that runs to 8500+, you can see it on you tube by searching on the words "bad day at el mirage" Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted August 28, 2008 Share Posted August 28, 2008 the little plate in the engine bay says it makes peak power at 5600rpm. makes sense too. My 78 pulls hard up to 6k, then dies. 6k is basically the shift point. but it will rev up to 6500+ (but it's not a good idea to) Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 28, 2008 Share Posted August 28, 2008 Yeah, in first and second I can bang the next gear at 6500 because of the gearing's mechanical advantage, but once you hit 3rd gear with a stocker L28, you will be running through the traps on a 1/4 mile well before upshift time to fourth, somewhere around 90mph. You will notice the loss of power above around 5500 at that point, and realize you just got to get to 6000 to be able to upshift and still get some sort of decent pull out of the next gear.... Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted August 28, 2008 Share Posted August 28, 2008 Yep, that's exactly what I notice. I try to avoid going up to 6500, so I usually shift just a tad after 6000. in 3rd I do feel a slight dip in power like you said. Actually having to rev it up to 6k to get a good pull out of 4th reminds me of the block brace spoon made for the honda civic. it makes the engine run smoother and bring its useable rpm range up to near 10k. you won't make much more power by reving it that high, but it helps since when you shift, you stay right inside the strongest point in the power band. but anyways, that's off topic... 3rd gear will top out a 90mph at around 6k I think, maybe a bit higher, so yeah, shifting into 4th wouldn't be much of any use. But because of that I sort of want to put a 3.70 into my 78 instead of the 3.545 Quote Link to comment Share on other sites More sharing options...
mikeyE Posted August 28, 2008 Author Share Posted August 28, 2008 thanks gise i appreciate all of your help looks like i got some work to do. ill update thank you thank you Quote Link to comment Share on other sites More sharing options...
Phantom Posted August 28, 2008 Share Posted August 28, 2008 Bottom line - redline on a tach in a 280Z is 6,500. It would seem intuitive at that point that the L28 is not, in stock form, designed to function well above that point. I've driven three L28 equipped Z's and my personal experience bears that out. The 280ZX motors are even more that way with a camshaft & head design that lowers and broadens the torque curve. Does much better on the lower end than the earlier iterations but still dies above about 6,300. Quote Link to comment Share on other sites More sharing options...
Daeron Posted August 29, 2008 Share Posted August 29, 2008 Our Bonneville LSR has an L28 that runs to 8500+, you can see it on you tube by searching on the words "bad day at el mirage" I prefer searching "9300 shiftpoint":shock: It may not be the number you have on the title of that vid, but I know I have searched at 9200, 9300, and 9400 and found it easily using any of those terms Quote Link to comment Share on other sites More sharing options...
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