mxgsfmdpx Posted August 8, 2014 Share Posted August 8, 2014 Datsun straight six gurus, I have a question... I have an L28 and 5 speed swap in my 71 240Z. The car pulls hard and smooth but seems to peak at around 5,000 RPMs. Anyone experience anything like this? Stock motor and dual SUs. I remember my L24 and 4 speed pulling hard all the way through 6500 RPMs. Thoughts? Thank you! Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 8, 2014 Share Posted August 8, 2014 Power Peak of L28 is at 5,300 rpms and is normally geared accordingly. Swap the cam from the L24 into the L28, and it runs like the L28. Case Closed! Better yet, get a good aftermarket cam and it will pull harder and right up to 6800 no issues.... Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 8, 2014 Share Posted August 8, 2014 Don't be misled, you likely make more power at 5300 with the L28 than you do at 6500 with the L24. It's misleading like a turbo because it's pulling so hard when it pulls, when that torque starts falling off, you think it's a big loss....when in fact your terminal speed is actually higher, and was achieved in a shorter time than with the smaller engine. Quote Link to comment Share on other sites More sharing options...
mxgsfmdpx Posted August 8, 2014 Author Share Posted August 8, 2014 Don't be misled, you likely make more power at 5300 with the L28 than you do at 6500 with the L24. It's misleading like a turbo because it's pulling so hard when it pulls, when that torque starts falling off, you think it's a big loss....when in fact your terminal speed is actually higher, and was achieved in a shorter time than with the smaller engine. That's exactly what I'm feeling! Okay, I'm not crazy then. Thanks very much, great info! Quote Link to comment Share on other sites More sharing options...
mxgsfmdpx Posted August 8, 2014 Author Share Posted August 8, 2014 Power Peak of L28 is at 5,300 rpms and is normally geared accordingly. Swap the cam from the L24 into the L28, and it runs like the L28. Case Closed! Better yet, get a good aftermarket cam and it will pull harder and right up to 6800 no issues.... What do you reccomend for an aftermarket cam? Not a race car obviously, but if a certain (hopefully somewhat mild) grind is going to get me more power in the higher RPMs I would be very happy to make a purchase Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 9, 2014 Share Posted August 9, 2014 Many advocate for a stock cam swap, IMO it's a huge effort for nothing. For the same effort, an aftermarket cam is much more worthy of the effort. It really depends on which head you have. From knowing the flow of the individual heads, you can set your lift, duration, and lobe centers to maximise breathing below 7,000 and wake up an otherwise sluggish engine. Giving something with the .460-.470" lift (max on stock springs as referenced in the various camshaft threads in the archives) will keep costs down, and then the opening and closing events can be tweaked for more power up top. There is absolutely no reason your L28 has to be that short-shifted slug that the stock cam mandates. A mild aftermarket camshaft will give you about another 1,500 useable RPMS of power and still come on strong at 3.500 rpms like the old L24 cams did. Pull hard from 3,500 to 6,500 with shift point in the 6,800 to 7,000 range. Very fun engine when set up like that. There are a lot of cams out there that fit this description...you just have to mill through the chaff and see who is happy with theirs, and hopefully they have dyno graphs to back up their butt-dyno impressions. Isky has a good selection of cams like that. But really, changing the springs and lash pads even on a stock head will allow more lift and that means more breathing at the top end. I'd put a 460/470 lift cam in a car I was selling to a kid. I'd put a 500-525" lift cam in a car I was keeping for myself! LOL Quote Link to comment Share on other sites More sharing options...
mxgsfmdpx Posted August 9, 2014 Author Share Posted August 9, 2014 Many advocate for a stock cam swap, IMO it's a huge effort for nothing. For the same effort, an aftermarket cam is much more worthy of the effort. It really depends on which head you have. From knowing the flow of the individual heads, you can set your lift, duration, and lobe centers to maximise breathing below 7,000 and wake up an otherwise sluggish engine. Giving something with the .460-.470" lift (max on stock springs as referenced in the various camshaft threads in the archives) will keep costs down, and then the opening and closing events can be tweaked for more power up top. There is absolutely no reason your L28 has to be that short-shifted slug that the stock cam mandates. A mild aftermarket camshaft will give you about another 1,500 useable RPMS of power and still come on strong at 3.500 rpms like the old L24 cams did. Pull hard from 3,500 to 6,500 with shift point in the 6,800 to 7,000 range. Very fun engine when set up like that. There are a lot of cams out there that fit this description...you just have to mill through the chaff and see who is happy with theirs, and hopefully they have dyno graphs to back up their butt-dyno impressions. Isky has a good selection of cams like that. But really, changing the springs and lash pads even on a stock head will allow more lift and that means more breathing at the top end. I'd put a 460/470 lift cam in a car I was selling to a kid. I'd put a 500-525" lift cam in a car I was keeping for myself! LOL Lol! Perfect. I'll do some more research on the subject. Thanks very much! Quote Link to comment Share on other sites More sharing options...
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