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A feeler thread for a potential mod(ification)

S

Smorgesborg

Active member
Joined
Apr 9, 2020
Location
Eastern MA
In short:
Alibaba 158mm H beams with 24mm wrist pin bushings, with crank steering (either 29.5mm wide or 29.75mm, TBD), and 4.8L/5.3L LS pistons.
How:
A bulk order of custom connecting rods from a factory I found through Alibaba. Pistons sourced from really anywhere, LS's are plentiful. The 33.655mm compression height of the LS combined with the 158mm rods is only a few thousandths of an inch lower than the compression height of the B230 pistons with 152mm rods. If it wasn't for the different rod requirements, it'd be a drop in replacement.

Why:
1. Weight savings
- 130g saved minimum vs conventional 152mm H beams and B230FT pistons
2. Greater Range of piston options for various purposes
- Overbore pistons for rebuilds are cheaper.
- flat tops, dished, cast, forged, etc are all available for the LS at low prices.
3. Makes a bored out B230 build closer within reach for less price
- the LS has a wide range of bores. Only needs to have a similar compression height and wrist pin.
4. More efficient
- Thinner rings
- Longer rods means better piston speed profile
5. Greater power potential vs stock
- Forged 4340 alloy steel rods are stronger than the factory 13mm ones

An explanation:
I came up with this idea for this mod, and I am looking to do it on my engine. While I realise crank-steered 158mm connecting rods are already in existence, I don't want to risk a relatively large amount of money by modifying the rods in order to accept the different wrist pin, nor do I think anyone else would.

China rods are cheap, CXracing 152mm's ones are popular, and I'm fairly confident, based on matching appearances, that a number of other well-regarded aftermarket sellers are also just reselling Chinese H-beams. I found a factory that makes custom connecting rods and has a pattern for a 158mm Volvo B230 rod, and allows for different small end bushing diameters. Downside, despite being relatively cheap, the minimum order quantity is 40 rods, and I don't have 10 engines to rebuild. I certainly don't want to absorb the entire cost if I just use 4.

And so, with that last point, I've come here. I'm probably not the first to have this idea, I've seen similar ideas floating around before, and I'm here to look for an additional amount of people to help me absorb the cost. The initial purchase would all be on me, of course, since you wouldn't want to pay for something before it's actually available, but I'm looking for people that would be willing to confirm that they'd be interested in buying such a package. The cost would be around 160 bucks for the package of 4, minimum. Might be more depending on shipping costs, the buy-in cost of this endeavor would just be enough to cover the cost I'm going to be putting in. Long term, if this works, I would be looking to sell these for more.

Since feeler threads aren't allowed in the for-sale section, and this is a performance modification, I've posted this here. Thanks for reading.
 
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culberro said:
What?s the bore range for LS engines?
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The LS engines start at 96mm bore, same as the B230. This is for the 4.8 and 5.3L engines. They are also available in 99mm, 99.6mm, 101.6mm, 103.25mm, 104.8mm, and 106.3mm, however the redblock bore spacing between cylinders 1 & 2, and 3 & 4 is 4.15 inches, making the 104.8 with a 0.5mm oversize to 105.3 (4.146in) the theoretical maximum, if you're brave enough.
 
Until a working/proven/reliable engine is made with these parts and all the machine work required and bits needed are documented, i'm sticking with the already proven stock/aftermarket parts. Sorry, but it's my honest opinion.
 
esmth said:
Until a working/proven/reliable engine is made with these parts and all the machine work required and bits needed are documented, i'm sticking with the already proven stock/aftermarket parts. Sorry, but it's my honest opinion.
Click to expand...

I 100% agree, that's why I'm frustrated that the cost of 158mm rods is too high to allow experimentation with modification, and why the buy- in cost for experimentation is just to cover what I spend to buy the rods.

Might be worth just buying a set with 23mm wrist pins, selling the 36 as normal performance rods, and modifying my own.

Edit to add: On that note, who'd be willing to buy Alibaba 158mm crank steered rods from me, for the standard wrist-pin sizing? Still want to go with china rods to save money on experimentation.

I maintain that, if this works, the greatest benefit would be to rebuilders. Oversized pistons are ridiculously expensive, meanwhile LS pistons are cheap even in the over-bore sizes, with many more options depending on damage to the cylinder. A set of these rods + a set of those pistons would be great to a rebuilder struggling to rebuild the engine they've modified, but messed up the cylinder wall of.
 
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shoestring said:
Exactly how far in the hole does the piston end up?
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With the 158mm rod? 0.00277165354 inches further down than stock, assuming you use a 1.324in compression height. A 1.327 inch compression height would be ideal to keep the stock compression height from the top of the piston to the centerline of the crank, but that's only a difference of 3 thousandths of an inch, in an engine where the popout can range from 0 to 10 thousandths.
 
Opening up the volvo specific 158mm rods to a 24mm wrist pin should be easy peasy for an engine machine shop.
 
culberro said:
Opening up the volvo specific 158mm rods to a 24mm wrist pin should be easy peasy for an engine machine shop.
Click to expand...

Very true, but my concern is that the cost to make this attempt to try this is a minimum of 400 dollars before shipping. If everything goes wrong, it'll not be good. Chinese rods from the source are cheaper.

Besides this, if it works, it'd be good to have rods available to do this without modifying anything and adding extra risk.

Is the solution then, to make my own attempt, see if it works, and then start advertising these rods? The issue is that the time for delivery will be very long for whenever I'd want to do this.
 
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You do know that MaxpeedingRod will make you a 4340 Forged H beam in just about any length/width/se bore/be bore... for less than 400$/set shipped, right?

Just got mine back from a trip to Stack Metallurgy for hardness testing. Turns out my 135$ shipped was worth it. I just asked them for an engineering sample of the size I needed and they shipped me 4. All checked out within 5 microns of my desired nominal, and hardness and metallurgy testing confirmed the alloy and type of manufacturing processes.
 
cwdodson88 said:
You do know that MaxpeedingRod will make you a 4340 Forged H beam in just about any length/width/se bore/be bore... for less than 400$/set shipped, right?

Just got mine back from a trip to Stack Metallurgy for hardness testing. Turns out my 135$ shipped was worth it. I just asked them for an engineering sample of the size I needed and they shipped me 4. All checked out within 5 microns of my desired nominal, and hardness and metallurgy testing confirmed the alloy and type of manufacturing processes.
Click to expand...

I didn't, thank you. I'm unsure if they'll offer the 158mm rods for the redblock, but we'll see.
 
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Smorgesborg said:
I didn't, thank you. I'm unsure if they'll offer the 158mm rods for the redblock, but we'll see.
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Thats just it, they offer a 158 for something else.... and since they are the manufacturer, they have blanks, then can bore the big end where you want and as big as you want, same with the small end :oogle:
 
Harlard said:
Seems like ya'll are wasting mental effort on a custom solution that already exists off the shelf, for a very reasonable price:

https://yoshifab.com/store/158mm-h-beam-connecting-rod-set.html
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400 bucks before shipping, to just take a reamer to it and cause potential problems. That's literally what I was describing in my post. Was also referring to them in a different way, elsewhere in the post.

Besides that, it'd need to be crank steered. Are the yoshifab rods crank steered? I can't find any info on it.

ETA: Yep, they're piston steered. They won't work.
 
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this seems like a waste of time ultimately. $200 or $400 to experiment with something is a fairly negligible amount of money, if you're getting that wrapped up about it now, I question whether you have the means to see this to fruition, and I further question whether you will get any further in your testing than I did with cheap 152mm rods and stock NA pistons.

If it's something you want to do, just go out and do it, don't complicate it with a group buy for an unknown right out the gate.
 
Smorgesborg said:
52mm, not 58.

The thing is that looking at their offerings, the rods will be at least 200 dollars. What did you buy your rods for?
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My rods are spec'd for my b20 build. But it seems you're missing the point. I paid under $400/shipped for a set of custom engineering samples. I was told that a bulk order of 25 sets (100 rods min) of that size would come out at around 200-250/set shipped depending on shipping method, quantity and timeframe. They want your business, and they will do most anything you want as long as they dont have to change up tooling. So finding that they have that C>C length already tooled up, and all they have to do is make adjustments to final machining, they're in it for nothing. Peanuts.

Also, piston steered vs crank steered isn't a huge deal. A custom or off the shelf forged piston allows you to get them piston steered if that is what you can get a rod for. Why anyone would throw money at rods and not pistons seems odd to me. Your LS piston options are most likely 19.75mm wide at the pin anyway so a 19.5mm wide small end would be just about correct for piston steered. Also, if your maths are ok, you can even run a simple pin spacer, if the pistons are too skinny, have the rods faced to size. Easily something that can be whipped up at most any machine shop.

On harlard's point, looks like YoshiFab already has a nailed down solution. Call summit and have them put a pair of calipers to the rod width of some chebby LS pistons and send Josh and e-mail. If the dimensions work out, order a set of pistons and have a spare set for when you blow a hole in em.
 
linuxman51 said:
If it's something you want to do, just go out and do it, don't complicate it with a group buy for an unknown right out the gate.
Click to expand...

Good point. If this works out as well as I expect it to, y'all will be the first to know.

cwdodson88 said:
Your LS piston options are most likely 19.75mm wide at the pin anyway so a 19.5mm wide small end would be just about correct for piston steered. Also, if your maths are ok, you can even run a simple pin spacer, if the pistons are too skinny, have the rods faced to size. Easily something that can be whipped up at most any machine shop.

On harlard's point, looks like YoshiFab already has a nailed down solution. Call summit and have them put a pair of calipers to the rod width of some chebby LS pistons and send Josh and e-mail. If the dimensions work out, order a set of pistons and have a spare set for when you blow a hole in em.
Click to expand...

1.01 inches at the pin, or at least that's the LS rod specs. Point is, it's wide up there at the pin.

Yoshifab has a 158mm solution, yes, that's why I knew it'd be theoretically possible to have a factory make rods with the right specs. Crank steered vs piston steered does matter, as while spacers for the wrist pin are possible it's obviously not preferable for long term reliability.
 
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