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Got myself an LD28 and an L24e. What to keep, what to use in a stroker build, what to discard?


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Hi!

 

This weekend I bought a complete LD28 engine and a complete L24e with a N47 head. I was only going to buy the LD28 but the guy also had the L24e so I asked him what he wanted for it, and ended up paying 200 bucks for the lot:)

 

SOO that calls for a stroker build. I took out the V07 diesel crank and it is in perfect shape! 

 

Are there any other parts from the LD28 that I should keep? I have read about converting the LD28 intake, but is there anything else worth saving?

 

What about the L24e? 

 

It came with the intake and electronic distributor. How is this intake performance wise?

 

 

 

I am planning on building a 3.1 stroker with megasquirt EFI. The long term plan is to run ITB's, but that is an expensive affair so I am thinking of a temporary solution with either the L24e intake and the N47 head, or converting the LD28 intake and use it with an E88 head that I also have. What do you guys think?

 

I know that both of these heads are not optimal for performance, but I am hoping to use the parts I have available for now :)

 

 

Regards,

 

Tomzern

Edited by Tomzern
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Seems like the simplest, cheapest, temporary engine would be the complete L24E package, with the LD crank, if just getting the crank installed is the goal.  And new pistons, of course.  Small valves, small intake, very high CR, and tuning to keep the engine from blowing up, but the crank would be in there.  If that's the goal of the temporary package.

 

Or just install the L24E complete and drive it while you get the other parts together.

 

From my reading, the "stroker" engine doesn't have the greatest HP/$ ratio.  I haven't built one, I just read a lot.

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A bit more info about my standpoint and thoughts:

 

As of now I have a stock L24 with the E88 head in the car. It runs good and I plan to use this until I have the 3.1 stroker ready with everything. 

I also have another L24 which is the original numbermatching engine with the E31 head (the car is a low-vin 1970 Z ). This engine is currently being restored to perfect original condition and will be a "backup engine".

 

The end goal is to have an L31 with megasquirt in the car and the numbermatching engine as a "backup" in good condition.

 

The L24E bottom end needs to be bored because the cylinders are bad. I think I will sell this complete bottom end or just give it away. It doesn't have much value as it is now. 

 

I have a good friend that works in a machine shop and he does all the balancing and required machining for the stroker build, so the HP/$ ratio will not be that bad:)

 

When I mentioned a temporary solution I was only talking about the intake. Will the N47 head and intake from the L24e work good on a L31 stroker?

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The guys that build engines on this forum say that the stock L28E intake doesn't even flow very well on the 2.8L engine it comes on.  You're talking about a head with smaller valves (the MN47 is not the same as the L28 N47) , and its intake manifold, on an engine that is 30% larger than the engine it was designed for (3.1 vs. 2.4).  Seems likely that it will be choked.  It will probably bolt up fine but be down on potential power.

 

And the CR might be high depending on the pistons you use.  ~13.2 with flat-tops, ~10 with dished.  Apparently the MN47 chamber's are about 39 cc.

 

http://forums.hybridz.org/topic/43671-n47-head-l28/

 

Just more stuff to think about.  You can make anything work, but "good" is subjective.  Good luck.

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The MN47 head is fantastic.  With some very mild porting work (port matching gaskets and cleaning up the valve bowls)  it will flow jsut as good as a 2.8 head, and with the smaller valves, you will get increased port velocity.  also, smaller valves means less valve shrouding.  Plus, with the small combustion chamber and its high quench design, it will be more efficient and require less timing advance for the same amount of power.  The valve size isn't really that big of a factor because the intake manifold runners  are so damn small on these engines.  

 

I would look into the LD28 intake manifold, if you have the means to convert it.  THe runners are substantially larger diameter than even an L28 manifold.

 

Someone was messing around with a dual throttle body set up using SU manifolds, but I do not know if this ever came to fruition.  Might be something to look into .   

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LD28 in running condition has become more valuable than it's crank alone recently.

I am in norway, so it's a little different here. Not many Z's here, especially not many stroker builds :)

 

 

The MN47 head is fantastic.  With some very mild porting work (port matching gaskets and cleaning up the valve bowls)  it will flow jsut as good as a 2.8 head, and with the smaller valves, you will get increased port velocity.  also, smaller valves means less valve shrouding.  Plus, with the small combustion chamber and its high quench design, it will be more efficient and require less timing advance for the same amount of power.  The valve size isn't really that big of a factor because the intake manifold runners  are so damn small on these engines.  

 

I would look into the LD28 intake manifold, if you have the means to convert it.  THe runners are substantially larger diameter than even an L28 manifold.

 

Someone was messing around with a dual throttle body set up using SU manifolds, but I do not know if this ever came to fruition.  Might be something to look into .   

 

Good to hear Mack!

 

Anyway, I just made another good deal! :) I asked for an L28 in the Patrol owners club here in norway, and found a guy that had swapped out his L28 with an LD28 :D So I am buying his L28 and he's taking my LD28 + about $80 extra as payment for the L28. I am of course keeping the crankshaft and also the intake manifold from the LD28. 

 

So then I have the LD28 crank, an F54 L28 block, and three heads to choose from. N42 from the L28, N47 and E88. I guess the N42 will be the best choice?

 

Is it necessary to buy forged rods and pistons for my stroker? The bottom end will be thoroughly balanced and weightmatched and I am not going to run it past 8k rpm. 

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You have forged rods already. Forged crank as well. Normally recommendation is to keep RPM's below 7500 with cast Pistons for durability.

 

Once you go forged Pistons, there is no restriction to your RPMS, restricting yourself to 8,000 is only giving you maybe 1,000 more useable RPMs. They can do far better than that.

Edited by Tony D
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You have forged rods already. Forged crank as well. Normally recommendation is to keep RPM's below 7500 with cast Pistons for durability.

 

Once you go forged Pistons, there is no restriction to your RPMS, restricting yourself to 8,000 is only giving you maybe 1,000 more useable RPMs. They can do far better than that.

 

Sorry, I know the rods are forged :P . I meant H-beam rods for added strength, but the original L24 rods are strong enough?

 

It would be nice to rev it past 8000 rpm :D

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  • 2 weeks later...

Use the LD block and crankshaft. The LD block is 19mm taller than a petrol block. Find a mechanical head P91A. Find a set of L20B rods and a L20B timing cover. Oversize block only if there is a ring ridge but try to stick to .020 over otherwise just cross hatch it. Use a P91A head gasket to determine which coolant passages will need to be pipe tapped and plugged in the block in relation to the coolant holes in the head. The cavitation feed hole near cylinder #1 will need to be blocked too so you'll have to route coolant around to the thermostat housing to keep that system functioning at startup. You'll recognize it when the head is set because it will be exposed near the mechanical fuel pump location. Block will need to be drilled/tapped to accept a large fitting for the PCV system. The oil screen and retaining plate (inside the block behind the PCV tube) will need to be scavenged from a petrol block. The block will need to be rifle drilled to relocate oil pickup and oil pan scavenged from petrol block. Have the head machined to accept 12mm head bolts and the guides in the block. Order custom pistons to suit your application (na, turbo'd, sc'd). Order a set of ARP 12mm hardened washers for the head bolts. Order a custom set of ARP bolts (ridiculous price!!!) or go to the local industrial park fastener supply. Get socket head 12mm grade 12.9 bolts (I don't have the info in front of me but I think the pitch is 1.25). The closest bolt length is about 1/4" too long so get these cut down on a lathe. There are no head bolts from any engine with the correct length and pitch for this application no matter what you might read here or elsewhere (I've got a couple sets of these bolts still in the garage). There are the basics for a strong long stroke square (bore/stroke ratio) 2.8 that can be rebuilt if needed. You may have to cut your motor mounts vertically and lower the engine about 1/2" to clear the hood and still clear the front crossmember too. A chunk of soft clay on the front of your stock engine valve cover will reveal how much clearance you have to work with. There is a bit more to this but I'm typing on the fly here.

Edited by ezzzzzzz
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