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3.4L L28 stroker


defrag010

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Twistex, could you provide more info on that LD28 build? Did you sleeve the block? There is the stock 84.5mm bore and only 12mm between bores on that block. The block is partially siamesed with an approximate 3mm gap between cylinders. That leaves approximately 3mm wall thickness stock. Your bore would remove 2.75mm of material leaving only .25mm of cylinder wall. That seems unreasonably little material to hold up to any combustion pressures over time.

 

Have you got any pictures of the LD28 block? It'd be great to compare it to a standard L28 block. I'm curious if there's a considerable difference in the distance between bores... Maybe custom sleeves would be a good solution to keep the block in one piece?

 

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I'll have to go by Abacus Racing to shot a photo. The block looks identical at first glance. The bores are smaller but spaced the same as the L28 block. It is about 20mm taller. There are two cast-in points for the oil pickup tube. one or the other is drilled through depending on the oil pan used. There are a couple of other minor differences (oil dipstick tube location, etc.).

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Crankwelding is done all the time with great results, especially known in the VW engine arena. Many places will actually hardface the journal areas so if they loose a bearing during a race, they won't have to replace or reqork the crank, just swap the crank to another case and replace a rod or two... And those are 10,000 rpm engine with turbos pumping 45psi + of boost in many cases.

 

Japanese were making 3.5L L28's in the 80's, and true to form, almost 30 years later someone here with enough time and curiosity has come across standard techniques that got him within 100cc's!

 

This is standard technology, it just takes application of the techniques to this situation to make it happen.

 

Five years ago many would have said an L35 DETT would have been impossible as well. Except me, since I've seen one....in 1986!

 

OH, and BTW, my understanding of the Japanese Build was that it was accomplished using liners. This was not some sedate engine, either! Full 7500rpms of useable engine speed...under boost!

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Crankwelding is done all the time with great results, especially known in the VW engine arena. Many places will actually hardface the journal areas so if they loose a bearing during a race, they won't have to replace or reqork the crank, just swap the crank to another case and replace a rod or two... And those are 10,000 rpm engine with turbos pumping 45psi + of boost in many cases.

 

Japanese were making 3.5L L28's in the 80's, and true to form, almost 30 years later someone here with enough time and curiosity has come across standard techniques that got him within 100cc's!

 

This is standard technology, it just takes application of the techniques to this situation to make it happen.

 

Five years ago many would have said an L35 DETT would have been impossible as well. Except me, since I've seen one....in 1986!

 

OH, and BTW, my understanding of the Japanese Build was that it was accomplished using liners. This was not some sedate engine, either! Full 7500rpms of useable engine speed...under boost!

 

Tony, what kind of VW engines are you reffering to? What head did this L35DETT have? Was it the same car that Alan T. (HS30-H) pictured during his stay in Japan?

 

I'm wondering about the rod to stroke ratio in the 3,5 litre engines that you mentioned. In a standard LD28 crank / L24 rod combo, r/s ratio is 1,6. A 89mm stroke crank with L28 rods would have 1,46 r/s ratio (a 89mm/89mm bore and stroke should give about 3,3 liters, still less than 3,5). That's not a lot, considering the fact that these engines rev quite high (7500rpms of usable engine speed?), and the forces pressing the piston against the cylinder wall increase by a large margin.

 

A taller block, such as the LD28 unit, could be a solution for this... Can't wait to see the LD28 block pictures! :)

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This is rather interesting. Were any of you guys at the JCCS last month? If so, you might recall the blue Kenmerri Skyline in full factory race guise. I was able to have a limited conversation with the owner, he speaks far better English than my Japanese, and he explained to me that his car in fact had a 3.4 L series. I did not note any of the specs he mentioned as I did not think there would be a discussion about this subject, but he did say that the crank had been welded and re-balanced. Anyhow, he said it has been running this way for over 10 years. And if any of you heard this car as it came in or left, you'd agree it was unlike any other L series you've heard. The thing sounded like a pissed off small block Chevy. I have little reason to doubt his claims. And as mentioned earlier in this post, all of us at one time or another have been told something was impossible only to find a way to silence the doubters. My opinion is that we should all cheer our bretheren on. They may well fail in the end, but isn't it better to see someone make the attempt and find out for sure that something can't be done? If we all just gave up when someone said it couldn't be done we'd all still be sitting in a cave wearing loin cloths. Even if I had not seen a 3.4 motor in person I'd say go for it.

 

Brian

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Generally a submerged arc welding process with wire feed on a special crank welding machine will be used.

 

The VW's I was talking about were Type 1 engines primarily, don't know what the Type 4 engines are doing, I know they are up above 2.8L now, from an engine that originally was 1700cc's I believe.

 

Spray Welding or Metallizing is not my favorite way to restore journals. Many people do it, but I prefer traditional submerged arc welding as it's a permanent adhesion, and can be offset ground as it's structurally similar to the parent metals. As was mentioned above, you can make cheeks, radius it, even lengthen it. You don't want to try that with spray-metallizing. In High Pressure Compressor Cylinders, Spray Metallizing will actually be forced off the parent metal and flake off in biug chunks trashing the cylinder and piston! Below aroudn 1100psi it's o.k., but above that you want a real liner...but I digress.

 

Monzster does raise another interesting alternative, it would not be the first time someone used a dissimilar rod with a smaller journal diameter simply offest grind an existing crank for stroke increase without any welding at all. I have some photos (old Film 5X7's) in an album of one of the cars I am referring to...in one shot when it was still OHC, it was a 3.3L, but in the later photos it has the OS Giken TC24B-1 head on it, on a new 3.5L block. This was at the paint shop, where the guy had all his work done. FRP doors, hood, hatch, fenders, G-Nose, Nissan Perspex Side and Rear Glass...superlightweight bodywork and over a million yen of Stereo in it to boot! And that was 1986...

 

There are lots of alternatives to approach the issue, it all depends on how the individual wants to go about it!

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Instead of welding the crank, how bout using a set of Toyota 3sgte rods and offset grind the crank to get 1.5mm more stroke (84.5). No welding and lighter weight. HMMM:D

 

Offset grinding doesn't mean no welding, unless the big ends of the rod are smaller than the L28 rod ends.

 

IF they're close in size, then offset grinding still might mean welding on the opposite side of the offset cut, right? I mean, you don't want an elliptical rod/crank journal, so welding on the opposite side to grind into round would be essential in most cases.

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This is rather interesting. Were any of you guys at the JCCS last month? If so, you might recall the blue Kenmerri Skyline in full factory race guise. I was able to have a limited conversation with the owner, he speaks far better English than my Japanese, and he explained to me that his car in fact had a 3.4 L series. I did not note any of the specs he mentioned as I did not think there would be a discussion about this subject, but he did say that the crank had been welded and re-balanced. Anyhow, he said it has been running this way for over 10 years. And if any of you heard this car as it came in or left, you'd agree it was unlike any other L series you've heard. The thing sounded like a pissed off small block Chevy. I have little reason to doubt his claims. And as mentioned earlier in this post, all of us at one time or another have been told something was impossible only to find a way to silence the doubters. My opinion is that we should all cheer our bretheren on. They may well fail in the end, but isn't it better to see someone make the attempt and find out for sure that something can't be done? If we all just gave up when someone said it couldn't be done we'd all still be sitting in a cave wearing loin cloths. Even if I had not seen a 3.4 motor in person I'd say go for it.

 

Brian

AMEN!

 

That's why I'm building an RB30DE and that's why NZEDER is too!

 

:D:biggrin:

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That's why the dissimilar Rods (Toyots 3SGTE), different journal diameter.

 

Same reason guys use 5.7" Chevy Rods (and recut the Journals) on Stroker VW Air Cooleds, and VW Type 4 Center Main Bearings on wleded strokers when used in Type 1's!

 

Problem was, you had to use the 'Good' Chevy rods, as some of them weren't forged in the early days! Kinda like cast cranks.

 

Man, thank Gawd I went with imports that come with all forged internals!

 

Or maybe that's the reason I went with them! LOL

 

I still remember my Fairlady Z with the hood open gathering all the looks back in Michigan: "Wow, Fuel Injection on a 1975?" ROMAFLOL

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hahahaha.

 

yeah apparently some dudes use chevy rods on RB30's too, but by the time you machine them to accept the proper bearing, cost runs up and it's not economical or beneficial in comparison to aftermarket RB rods.

 

So would the 3SGTE rods work in this application?

 

I say go for it!

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  • 4 months later...

Yeah, probably. But I know that 4G63 rods will :)

 

 

THey handle quite a bit of power in stock form well, are 150mm long, and have a 5mm smaller bore...make that a 87.5mm crank throw...No welding needed.

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