L28 Fast Road Engine Rebuild - Advice Wanted!

[Woody928]

Just catching up here finally!

Maxspeeding rods do L24 and L28 length rods. 133 and 130 respectively I think. The longer the rod, the smaller the angle deviation from straight up it has at the little end, and the smaller the angle the less thrust there is against the bore which means less wear and more power.
But, there's not a huge difference between 130 and 133.
Whichever you pick, you need a piston with a pin height to match.

You can definitely get 200 fwhp out of stock displacement and pistons and rods as long as they're all in good nick.

If you do swap to maxpeeding rods (or any other decent aftermarket rod I expect) they're full floating pins so you'll need pistons with gudgeon pin retaining clips.

Ahhh, thank you very much! So on that basis, given the choice the L24 rods are preferable as they should put less wear on the engine and make more power?

Good to know, this all sounds very encouraging! I think I'm looking at anything that's cost effective to pep it up a little bit without going mad on the spend. I mean if there's more displacement on offer then I feel it would be stupid not to take it while I'm there. The one thing I would like to know though is, what are the performance advantages of going for forged rods/pistons over cast items?

Woody,
Since so many of us are following this engine build because we want a similar build, would you be so kind as to list out items you eventually purchase?
That would be a great help.
If any of the items are ordered from the states and they give you a problem with POST, you can ship them to me and I will forward to you if that helps.
Mike

Hahaha, more than happy to be the club guinea pig! Once I finally get there then I'm more than happy to share. I'm sure there's lots of knowledge and experience that can be contributed by the wiser members on here to help me get to the end product.

You're a true gent as always, I'll certainly keep that in mind. Thank you!

This just turned up so I've got a lot of reading to do and an engine to strip down in the coming weeks to see where we stand. I doubt any machining work will be able to be done for a while in the current climate though!

 

[richiep]

The L24 rods are only going to work with an LD28 crank - or custom pistons with a pin height that compensates = more expense.

If you are talking about 2.8-3.0, that can be done with L28 crank, L28 rods, and L28 pin height pistons from 86-89mm diameter.

You need to do some reading on the measurements associated with crank, rods, and piston overall and pin height. There’s a good Kameari reference pic somewhere (might also be in their catalogue) that helps explain the combinations. I’ll try and find it.

 

[Albrecht]

Needing something to keep myself busy I'm planning on stripping down the L28 N42 - F54 combo that I have sat in the garage and doing a ground up rebuild ready to drop into my 240z.

If your stock F54 block pistons are dished, they will answer the question as to whether you can use them or not themselves.

One of the side benefits of aftermarket (often forged) pistons is that they will usually have valve relief pockets machined into them already. They will also allow you to increase compression without taking too much meat off the cylinder head casting.

 

[jonbills]

I don't know the benefits of forged over cast, but another benefit of good aftermarket parts is they have more consistent weight than original. Parts. E.g. The maxpeedingrods are within a gram of each other across the set of 6.

 

[Woody928]

The L24 rods are only going to work with an LD28 crank - or custom pistons with a pin height that compensates = more expense.

If you are talking about 2.8-3.0, that can be done with L28 crank, L28 rods, and L28 pin height pistons from 86-89mm diameter.

You need to do some reading on the measurements associated with crank, rods, and piston overall and pin height. There’s a good Kameari reference pic somewhere (might also be in their catalogue) that helps explain the combinations. I’ll try and find it.

Thanks for clarifying Richie, sounds like picking up the max speed L28 rods would be a good option keeping the stock crank. For reference do you know where you can get off the shelf pistons to suit?

Also talking of boring the block out, what's the consensus of going out to 89mm? Is it too much? Part of me is thinking it may be more prudent to stop at 88m so that there's still more meat in the block from the reading I've been doing.

If you do find that Kameari reference then that would be amazing! I'm trying to get my head around the bottom end first before thinking towards the head (excuse the pun).

If your stock F54 block pistons are dished, they will answer the question as to whether you can use them or not themselves.

One of the side benefits of aftermarket (often forged) pistons is that they will usually have valve relief pockets machined into them already. They will also allow you to increase compression without taking too much meat off the cylinder head casting.

Thanks Alan, I'll post up pics once I've stripped it down. Thank you for the insight, very helpful as ever!

It sounds like for this build while forged would be nice, cast should be more than man enough for the job and keep the budget way down.

I don't know the benefits of forged over cast, but another benefit of good aftermarket parts is they have more consistent weight than original. Parts. E.g. The maxpeedingrods are within a gram of each other across the set of 6.

Thanks Jon, I think the max speeding rods seem like a no brainer from a budget and compromise stand point of view. I'll just need to work out a bore size and suitable pistons to match before buying anything. What are you running in yours out of curiosity?

 

[Woody928]

Oh and while I remember, can anyone advise what size bolts I need to get my engine mounted on its nice new engine stand that's sitting there assembled and waiting?

 

[jonbills]

Thanks for clarifying Richie, sounds like picking up the max speed L28 rods would be a good option keeping the stock crank. For reference do you know where you can get off the shelf pistons to suit?

Also talking of boring the block out, what's the consensus of going out to 89mm? Is it too much? Part of me is thinking it may be more prudent to stop at 88m so that there's still more meat in the block from the reading I've been doing.

If you do find that Kameari reference then that would be amazing! I'm trying to get my head around the bottom end first before thinking towards the head (excuse the pun).



Thanks Alan, I'll post up pics once I've stripped it down. Thank you for the insight, very helpful as ever!

It sounds like for this build while forged would be nice, cast should be more than man enough for the job and keep the budget way down.



Thanks Jon, I think the max speeding rods seem like a no brainer from a budget and compromise stand point of view. I'll just need to work out a bore size and suitable pistons to match before buying anything. What are you running in yours out of curiosity?

mine's at 88.5 Mark, just so I could say it was "proper" 2.9. At 88mm it is still just a 2.8!

 

[Albrecht]

Oh and while I remember, can anyone advise what size bolts I need to get my engine mounted on its nice new engine stand that's sitting there assembled and waiting?

If you are going to use the block to bellhousing threads in the block, then M10 x 1.5 pitch. This is the same as the head bolts and used head bolts make good engine block 'stands' and block-to-engine-stand attachments, with suitable spacers. Make sure you use all four on the stand though, as a six cylinder engine is very long and front-heavy on a stand.

Factory recommendation was to bolt to the stand from the SIDE of the block, which is certainly safer...

 

[Albrecht]

If you do find that Kameari reference then that would be amazing! I'm trying to get my head around the bottom end first before thinking towards the head (excuse the pun).

Here's the Kameari Engine Works block/crank/rod/piston combo diagram. Relatively self-explanatory:

 

[richiep]

Here's the Kameari Engine Works block/crank/rod/piston combo diagram. Relatively self-explanatory:

And there you go! It’s a very useful reference sheet for all the common combinations. It can also give you a frame of reference for more creative combinations (welded and offset ground cranks, Toyota rods, etc.).

 

[Albrecht]

It sounds like for this build while forged would be nice, cast should be more than man enough for the job and keep the budget way down.

The point about cast vs forged pistons is that choice for aftermarket pistons tends to be biased toward forged. Not that many off-the-shelf custom piston choices are cast. And if you're going for aftermarket rods, watch out for (piston) pin type when you choose pistons.

As I mentioned before, aftermarket pistons will often have valve clearance pockets pre-machined into them. This will future-proof you against the chances of valve/piston 'interface' (with accompanying soundtrack...) if your cam choices make that more likely...

I'm getting the feeling you will soon refine your piston choice to something supplied by JE Pistons in the USA, or K.E.W. in Japan.

 

[Alphabettispaghetti]

For the extra cash, it’s got to be worth it. If you had forged rods and cast pistons, you’d eat up half the cost having the pins modded to suit the rods.

the Kameari are also cheaper than buying in the uk or sourcing from the US

 

[Albrecht]

http://kameariengineworks.co.jp/Catalogue-v3/Catalogue-v4/v4-catalogue-005-20181120-3.pdf

http://kameariengineworks.co.jp/Catalogue-v3/catalogue-007-20191110-2.pdf

http://kameariengineworks.co.jp/Catalogue-v3/catalogue-new-Leng-WEB20191021.pdf

 

[johnymd]

Things can add up fast.

 

[Woody928]

If you are going to use the block to bellhousing threads in the block, then M10 x 1.5 pitch. This is the same as the head bolts and used head bolts make good engine block 'stands' and block-to-engine-stand attachments, with suitable spacers. Make sure you use all four on the stand though, as a six cylinder engine is very long and front-heavy on a stand.

Factory recommendation was to bolt to the stand from the SIDE of the block, which is certainly safer...

Perfect, thank you very much Alan! If I was going to take the safer option on the side of the block then would the bolt size be the same?

Things can add up fast.

I'm certainly realising this the more that I look around!

I need to actually cost up the price alternatives however I'm beginning to get the impression that the options are to go cast which is far more affordable however you're then limited to 87mm off the shelf pistons. Or chasing a bigger bore up to 89mm which will mean going down the route of forged rods and pistons to match at significantly greater cost. I know what would be nice but I need to keep a budget in perspective.

Part of me is kinda tempted to build a future proof bottom end as I don't ever plan on going back there again however money... This is before I even start thinking about what to do with the head which is clearly one of the most crucial bits. Expensive business!

 

[richiep]

Factoid- the factory L-series rods are forged. So talking about replacing stock with “forged rods” isn’t actually the distinction people think it is. The upgrade element of the aftermarket rods comes in the lightweight H or I-beam designs and consistency of weight within a set. Factory rods can be prepped for hard performance use - just effort and money. The Maxspeeding rods just offer a more cost effective alternative these days.

 

[Albrecht]

Perfect, thank you very much Alan! If I was going to take the safer option on the side of the block then would the bolt size be the same?

Depends which holes you use. I'd have to look up the factory advice for this (I've seen photos/diagram somewhere) but I think you could use the bellhousing bolts threads for the 'short' block safely and just try to avoid having a full engine (ie - with cylinder head in place) hanging off it too long. It makes my toes wince...

I need to actually cost up the price alternatives however I'm beginning to get the impression that the options are to go cast which is far more affordable however you're then limited to 87mm off the shelf pistons. Or chasing a bigger bore up to 89mm which will mean going down the route of forged rods and pistons to match at significantly greater cost. I know what would be nice but I need to keep a budget in perspective.

Kameari Engine Works can supply a forged piston to use with stock (forged!) L28 connecting rods and stock (forged!) L28 crankshaft. In 89mm size this would give you a swept volume close to 3 litres. That would be a good bang-for-buck off the shelf choice, but people are liable to point out that the stock L28 rod length is "not ideal"...

And that's one of the problems with asking a question like this on an open forum. There are many ways to skin this cat and many of the opinions and recommendations you will get are each as viable as another. Only you can say where you want to get to, and choose how you want to get there. You'd probably be well advised at this point to focus on stripping the base engine down, learning how it comes apart (which will help you put it back together again) and cleaning, bagging/noting the stock components (even if you're not going to use some of them) whilst not forcing yourself to make any decisions about modifying or aftermarket parts just yet. And reading the books. The books! Read the books.

Definitely read, and read again, the books.

 

[jonbills]

FWIW, I've had my full engine on the stand for many weeks, mounted longways. I did always prop the far end with a bit of 2x4 though. I tried but I couldn't mount it on the side, but it would have needed a bracket making.

 

[johnymd]

I mounted an engine the regular way on a “normal” stand. It looked a bit heavy for the stand but I thought it must be ok as it’s designed for engines. Whilst moving it one day a front caster just snapped at its mounting and the whole thing went crashing over. Very lucky that nothing got damaged including myself. I would do as John suggested and prop with a bit of 4x2.

 

[Alphabettispaghetti]

I like the way you’re forging ahead with this, trying best not to cast a shadow on one option or another. Either way you choose will produce great results, I just wouldn’t want you to look back and see you’re own shadow cast over your engine while others have forged ahead, leaving you feeling limited by past choices while the world around you raises their limits.





























































fit forged pistons.