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Chris_Hamilton

Questions About Core Shift In L28 Blocks.

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So I've been lurking here for a while and I read several threads where it was discussed that core shift is an issue in both the N42 and F54 blocks.  I then went to Les Collins site where he stated that only 1 in 6 blocks could handle being bored to 89. This came as a surprise to me as I've never seen it discussed on Hybridz or anywhere else. I tried to discuss it over a hybridz and everyone seemed to dismiss the idea. I for one believe someone who has come to a conclusion as a result of testing rather than repeating something that gets said over the internet and is passed on as truth. That being said there are a lot of guys running 89mm pistons that have probably never had the block sonic checked prior to boring it out. Is the .120 minimum mainly for racing or engines that will see extended high rpm's or will a street motor survive with less. Just curious what some of you think. Also did the core shift issue affect all years? I've always read that the Japanese preferred the 75-76 N42 blocks for overboring. Is that a wives tale too? I've been collecting 75-76 N42/N42 motors with the idea of doing the 89mm bore along with the LD28 crank. (been collecting those as well....Collecting this stuff starts getting expensive and hard to explain to my wife as well. :o

 

I'd appreciate any thoughts you guys have.

Edited by Chris_Hamilton

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I don't place much value on the information in HybridZ - mostly just full of 'talk' and people of little to no practical experence. Lot's of people guessing & old wives tales too.

When you have this much core shift:

IMG_20150504_173543_602_zpsy1y4ug4t.jpg

...sonic testing is a MUST.
N42. F54. Early blocks. Late blocks. It doesn't matter - I've seen both types with with sizable core shift.
It's simply pot luck as to which block is able to take a larger bore.

I work for Les 1 to 2 days a week, and he's also performed the engineering on my L33.
I bought 4 L28 Long motors (N42 & F54 castings) and only 1 - an F54 - was suitable for a 89mm bore

 

I've seen Les - twice now - buy a 4 engines on a pallet. Pop the pistons out, then out comes the sonic tester & the blocks are tested.
Les is damn lucky to get one that will take a 89mm bore. Getting one that will take a 90mm bore in nigh on impossible...

In the end though, 89mm bore is not the be-all, end-all of L6 performance.
In reality, a 88mm bore engine won't feel any slower on the road compared to one with a 89mm bore.


 

Edited by Lurch ™

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Also .120thou is the accepted industry minimum for cylinder bore wall thickness.
Yes you can come down under that, at the expense of bore wall movement causing ring sealing issues, resulting in blowby etc.

And LD28 cranks are old hotness. Modified 89mm stroke RB items are the new hotness.
Why muck about with a piss-ant 83mm stroke when you can have one of these bad-boys, machined & prepped ready to go for an extra $1900?

P1030326_zpskobl5pmd.jpg

Edited by Lurch ™

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Good to see Chris is asking the question , which means he has his doubts about hybrid as well .

But it's good you have answered the question. You guys at LCR have set a very high bench mark that won't be mached.

Good luck Chris, do as Lurch has said and you'll build a good engine. Cheers.

Edited by Gordo

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Used to go through 20 x L20B four cylinder blcks, to find jst one, that could be built into a 2.4 litre stroker for rally se.

Plenty ere ok for 2.1-2.2 litre, a few were k for 2.3 litre.

Nissan knew their regular production blcks were only capable of being taken out so far, so, for competition se, they made special blocks

aimed at competition use.

Sadly, not for six cylinder ones!

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I tested four L28 blocks recently for my stroker to find one suitable to take to 89mm bores.

 

While buying parts I had email correspondence with a well know L-series builder in the USA who told me he doesn't even sonic test his over bored builds!

Edited by Gareth. J.

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Lurch you are correct in the 88 versus 89 mm statement as I have built many L 28 particularly turbo engines, of which cylinder pressures will be usually higher, so I run a max of 88 mm, my biggest concern is when the wall thickness is at its thinest on the thrust sides versus the pin boss sides as the cylinders are co-joined on pin sides proving much more resistance to flex an ballooning, that said it is always the job of a good engine builder to check, check and check again. Yes the RB cranks are very nice fast spin up items, a light flywheel and low inertia clutch with bring the engine on song very quick.      

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 Les Collins site where he stated that only 1 in 6 blocks could handle being bored to 89.......

 

a lot of guys running 89mm pistons that have probably never had the block sonic checked prior to boring it out

 

 

Also consider that one is a high-end professional builder of performance engines who will do anything to get every last ounce of horsepower and reliability out of the build.

 

The other may be a backyard builder who is happy to take his block to the local machine shop, get it bored out and whack some 89mm pistons in. He may not know or care that he is potentially losing power or reliability through poor ring sealing, etc, and is just happy that it runs OK and he can post up on a form that he runs 89mm pistons.

 

Slight exaggeration perhaps, but you get the idea.

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You guys are great, thanks for all the responses. Much better vibe here than over at Hybridz. One thing I've noticed over there is that one certain guy has to comment on everything, and he has a group of sycophants who tell him how great he is. I couldn't understand why everyone over there dismissed Peter MC when he was talking about some of work he had done. Reading his posts was like a lightbulb going off in my head. I had to find out more.Like Mr. Lurch said lots of talk and not much practical experience. But that is most Internet car forums I guess.

Do wish you guys were'nt halfway around the world as I'd love to get Peter, Les, Lurch to do some of the work. Unfortunately my budget will probably keep me from that.I have 4 N42/N42 motors and one E88/N42 I'm hoping that one of those will work out. I know it's just a number but it's kinda stuck in my head to do it. But I won't if I don't have a block that will pass the .120 minimum. One thing I've thought about doing, I've done it with V8's in the past was if I have a block that will bore to 89, doing a half fill with block filler. I've had several Ford 351W's strokers that I've done the half fill on, added a bigger radiator, and oil cooler and drove on the street with no issues whatsoever.One I put close to 50k miles on and it didn't use any oil whatsover.   Anyone tried that here?

Lurch where can I get that crank? Approximate cost?

I've got a lot more questions that I hope you guys can answer I hope you will bear with me. But for now, thanks.:)

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I did a half fill of 'hard blok' on my stroker. So far it's been fine, I've given it a hard time on the road during hot weather and water and oil temps were fine. I'd guess and oil cooler would be required for track work though.

 

It was a little hard to get it poured into the block but with a second person it wasn't too bad. I filled up to the bottom of the water pump inlet.

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Grout filling is is done on L6's, but it's a bit of an art to do correctly...

 

Chris - the 89mm stroke crank is around AU$2800 including the billet flywheel.
So in essence, I bet it's around $2700 more than your willing to pay :P

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Grout filling is is done on L6's, but it's a bit of an art to do correctly...

 

Chris - the 89mm stroke crank is around AU$2800 including the billet flywheel.

So in essence, I bet it's around $2700 more than your willing to pay :P

 

Why would you say that? I'm not cheap. ^-^  $2800 AU works out to about $2100 USD. That's a killer price imo. Especially with a flywheel. I've got 3 LD28 cranks, could sell a couple and darn near pay for that. If memory serves are you guys using Honda rods with that crank? What is the rod/stroke ratio like with an 89mm stroke? What about the pistons is the pin going through the bottom ring land?

Could you give me some contact info?

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FWIW I sold my LD28 crank because I figured if I ever wanted to go a stroker motor I'd pay more and go with the option Lurch described.

 

LD28 = old school hot rodding.

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My 89mm block is grout filled, 3.35L with the RB30 crank and used on the street too fwiw.

Edited by d3c0y

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My reasons to be RB stroked

 

1) I went with the RB crank because I am old (er) and wanted to impress my children and their fends.

I say I have an RB crank in my engine and they say "wooo thats cool!" I am sure if I said I had an LD28 crank they would say "thats great Jeff" like they do for most things.

So RB crank = Jeff feels like one of the kids..................

2) Les told me to.....

 

Jeff

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So pleased to hear that it's just not here in Australia that we have dodgy builders, I do feel your pain Allan.

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