Farmer Joe Posted January 11, 2012 Report Share Posted January 11, 2012 i have an opportunity to build an LZ24, and im looking for some feedback from anyone thats had one, built one, shit like that... the real world down and dirty.. ive gone through every lz24 thread i can find and no-one ever pans out on getting one done, or has already blown/parted one out.. im not worried about whats needed to build one, but mainly looking to find out what would be the best cam/ valvetrain recommendations.. the plan on my end goes, im going to be using the surrounding engine parts from my l20. ive currently got a U67, with minor porting on the intake ports and intake itself.. this head has a stock l20 cam.. i dont feel thats going to be enough to get the "full" potential fro this combo.. how much different are the cam specs on an l20 vs z24? i know the l20 cam will get it running, and ill have inherently more toque, but the power limit of the l20.. bottom line is, whats the sweet spot for cam specs on this type of build? anyone wanna share some specs on maybe some of the lz23 build im seeing? thanks Quote Link to comment
Sealik Posted January 11, 2012 Report Share Posted January 11, 2012 The Z24 build would be no different than the bored Z22...other than the TC, chain and HG prep...etc.. of course.... :D Head work/cam lift/duration etc is relative to how you would run the engine. Shooting for bottom or top end? Quote Link to comment
mike Posted January 11, 2012 Report Share Posted January 11, 2012 Im curious on this as well... One question, that you might have as well, is if anyone has ever gotten the timing right for the full powerband, from idle to redline. I talked in depth with the local Datto wizard and hes got an LZ24 with efi and a couple other tricks in a 720 that he uses for towing and he pretty much said that with the machine work and the inherent drawbacks of the combination that he wouldnt do it again he would just build an LZ22. I think the problem was only being able to tune it for a narrow powerband without having detonation occur... but its been a couple years since the conversation... Quote Link to comment
Z-train Posted January 11, 2012 Report Share Posted January 11, 2012 Shooting for bottom or top end? This is all that matters. Quote Link to comment
Z-train Posted January 11, 2012 Report Share Posted January 11, 2012 Im curious on this as well... One question, that you might have as well, is if anyone has ever gotten the timing right for the full powerband, from idle to redline. I talked in depth with the local Datto wizard and hes got an LZ24 with efi and a couple other tricks in a 720 that he uses for towing and he pretty much said that with the machine work and the inherent drawbacks of the combination that he wouldnt do it again he would just build an LZ22. I think the problem was only being able to tune it for a narrow powerband without having detonation occur... but its been a couple years since the conversation... Cam determines powerband-NOT tuning. Quote Link to comment
Farmer Joe Posted January 11, 2012 Author Report Share Posted January 11, 2012 mainly going for just a torquey l-series.. i dont need to rev it to the sky, but a 5-6k redline would be safe.. i would like to use 390s gearing with this engine, but it will prolly see the 437s before that.. im unsure what tranny itll end up with for now.. the l20 lacks bottom end grunt.. i think just the upgrade in stroke an bore is going to give me alot more bottom end, but id like to still get a bit of revs from it for gettin on the freeway and such.. kinda just trying to figure out how much more cam from the l20 ill need to support the extra 400cc.. im hapf temped just to slap it together and upgrade cams after getting it dialed in.. Quote Link to comment
datzenmike Posted January 11, 2012 Report Share Posted January 11, 2012 I measured the Z24 cam once ... has same lift, duration and overlap as the L20B cam. Everything except the block/internals on the L20B goes on the Z24 block. Everything forward of the block surface, oil pan, head and manifolds. The top of the timing cover needs to be extended 2cm because of the Z24 block being 2cm taller than the L20B block. Timing chain lengthened 4 cm. I would port match the head and both manifolds to the gasket. Use the U67 head but definitely get an L16 exhaust manifold... they are basically a cast iron header. See Hang_510 (Brian) on here... he's run an LZ24 and might still have the modified L20B timing cover too. The Z24 head has a larger combustion chamber so putting a smaller L head on will up the compression to 9.47 You will have more torque because of the increased stroke and displacement and not because of the L20B head and cam. I would say they will be about the same, possibly the Z24 would have a bit more bottom end grunt but the L20B head will 'come on' before 3K and lead the way after that. Quote Link to comment
Sealik Posted January 11, 2012 Report Share Posted January 11, 2012 The Z24 head has a larger combustion chamber so putting a smaller L head on will up the compression to 9.47 That would be with the closed chamber head.....correct?.... :D Drop to 8.4ish with the U67.....? Based on a stock 89 mm bore Quote Link to comment
Farmer Joe Posted January 11, 2012 Author Report Share Posted January 11, 2012 so if the cam specs are alike, then is there a difference in valve size on the z24 compared to the u67? my u67 head has been matched on the intake side.. my exhaust is not an issue either.. am i just over thinking the whole thing? will the l20 cam and head be anymore restrictive than the z24 head in stock form? Quote Link to comment
Jester Posted January 11, 2012 Report Share Posted January 11, 2012 Doug, clean out your PM's! Quote Link to comment
Sealik Posted January 11, 2012 Report Share Posted January 11, 2012 Doug, clean out your PM's! Wha...wha...what? Sorry.....should be some space in there....??? Another facet of hoarding............ :D Quote Link to comment
datzenmike Posted January 11, 2012 Report Share Posted January 11, 2012 That would be with the closed chamber head.....correct?.... :D Drop to 8.4ish with the U67.....? Based on a stock 89 mm bore I wish. No, the peanut head goes to 10.01 Quote Link to comment
Farmer Joe Posted January 11, 2012 Author Report Share Posted January 11, 2012 so if the cam specs are alike, then is there a difference in valve size on the z24 compared to the u67? my u67 head has been matched on the intake side.. my exhaust is not an issue either.. am i just over thinking the whole thing? will the l20 cam and head be anymore restrictive than the z24 head in stock form? Quote Link to comment
albyneau Posted January 11, 2012 Report Share Posted January 11, 2012 The Z24 build would be no different than the bored Z22...other than the TC, chain and HG prep...etc.. of course.... :D Head work/cam lift/duration etc is relative to how you would run the engine. Shooting for bottom or top end? Z22~ 92mm stroke, Z24~ 96mm stroke Quote Link to comment
HRH Posted January 11, 2012 Report Share Posted January 11, 2012 My Datsun guru has an LZ24 in his shop truck that he built eons ago with 13:1 compression. The thing is a torque beast. Given the chance to do it over he would just go with a Z22. Ten times easier, almost the exact same motor with the exception of crank stroke. The pain in the ass of making your own timing chain and custom timing cover versus using a Z22 that just fits makes the LZ24 less of a cost effective idea. In other words, it's not worth it unless you really want that extra torque or originality. Or if it's what you have, as was the case with my KAZ24. ;) Quote Link to comment
Farmer Joe Posted January 11, 2012 Author Report Share Posted January 11, 2012 wow, 13:1 is a bit extreme for even myself.. lol in any case, the whole putting the physical parts together is nothing im scared of. the timing cover deal is an easy fix. everyone knows to use the l20 timing cover and you end up with that 3/4in gap. i figured to just make a spacer from something that wont freak out from the heat. but it would just be a horseshoe shape like the space its filling. use 3/4in longer bolts on the 2 on the front of the head. simple. the rest of it then it just a big-block L-series. im gonna have to redo some little things.. i know itll interfere with my hood. im gonna have to figure that out when the time comes.. my air cleaner right now is like 1/4in away from the hood. also the exhaust downpipe, but thats a piece of shit right now anyway. the main thing im worried about is if the l20 head and cam is gonna be more restrictive than the z24 head and cam.. if mikes saying the cam profiles are alike than the big difference is the head design and the valve size. once again, i think im just overthinking the whole thing.. i think i need to just do it. Quote Link to comment
HRH Posted January 11, 2012 Report Share Posted January 11, 2012 Z24 head flows like dog shit. L head flows much better. Z24 head starts gasping at 4500 with a stock cam. Most race Z24s didn't go over 5500. Great torque motor, not a wrap motor. If you read the Datsun bible you'll see why. Port angle is the main difference. The hemi head of the Z is desirable but the gas can't get out. Valves are too close together for high rpm on napsz heads. L is much better, and also smaller, hence the high compression. Quote Link to comment
Farmer Joe Posted January 11, 2012 Author Report Share Posted January 11, 2012 understandable. with the combo im going to use, the stock z24 bottom end with a stock headgasket and the U67, mikes says its 9.4:1. not worried.. already run 93 all the time.. I think this has affirmed my curiosity.. I have good feelings about this... i think now ive gotta source some rod bearings and various gaskets.. Just as a reminder, what headbolts does one use with the lz24? Quote Link to comment
Wide14u Posted January 11, 2012 Report Share Posted January 11, 2012 I'm thinking its time to get started :D Quote Link to comment
HRH Posted January 11, 2012 Report Share Posted January 11, 2012 Same headbolts as the L20B. It's basically the same block minus the extra height. I would highly recommend a stud kit from ARP. Only $100 bucks. The bolts from the dealer will probably cost $60-$80 depending on your hookup. You can reuse them but I try not to on new motors unless budget is a concern. Quote Link to comment
Farmer Joe Posted January 11, 2012 Author Report Share Posted January 11, 2012 Right on matt! Well now we start pricing out this build.. Quote Link to comment
datzenmike Posted January 12, 2012 Report Share Posted January 12, 2012 I slipped L valves into a Z head, they fit but are 1/8"? shorter. Use Z24 gasket and trim the front off. Graft an old L gasket on the front around the timing gear. Use an old gasket and a thin smear of RTV, yes this is one time you can use it. The Z head ports are level with the block with a fairly sharp bend into the cylinder at the valves. Cylinder filling is fine at low speed but as mentioned falls off above 4K as the air is pinched at this choke point. L series intake ports enter the head much higher up and fall downhill to the valve. The Z head has three things that are desirable. Cross flow design keeps the hot exhaust on the other side of the head away from the intakes. Hemi combustion chamber shape. Dual plugs. All three work well together to make a ping resistant motor. Quote Link to comment
HRH Posted January 12, 2012 Report Share Posted January 12, 2012 And if you plan accordingly and run a very tall rear end gear, you could make a very usable engine out of the Z24 (at this point it would be just a Z24) assuming you're okay with only revving to 5k. Kind of like a little tractor. ;) Quote Link to comment
Farmer Joe Posted January 12, 2012 Author Report Share Posted January 12, 2012 i know im gonna start off with my current 437s. id like to try a set of 390s when ive got an extra 100 bux.. theres lots of gearsets here in the yards. 370s might even do the trick.. who knows.. Quote Link to comment
Z-train Posted January 12, 2012 Report Share Posted January 12, 2012 My LZ-23 has 4.37's behind it now.I have a 3.89 set ready to go.For just driving the 3.70's would be fine,but i still need to use it as a truck. Quote Link to comment
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