*Custom Rod Selection*

[Ba82Ep3]

The next shortblock im putting together is gonna be something out of the ordinary. Im not looking to drag race, make a dyno queen, or too concerned about rod ratios... this is just a full on hobby to me. I like to do the majority of the work myself, but this is gonna require SOME external and aftermarket influence.

I have the block, the pistons, and the crank (i would feel better about getting my hands on a better crank...), but i need rods.

Heres the basics:

k20z1 block bored to 87mm (stock sleeve w/blockguard)
k24a crank
k24z pistons/rings/wristpins (87mm)

The intent:

11.0:1
7500rpm
Bore 87 Stroke 99 = a high 2.2L
Boost, but no more than 9-12psi

I know there is a suggested limit of 86.5mm on the stock sleeves. Im aware of the potential issues of 'going big' on the stock sleeve. Im aware i may need to clearance the block for the crank/rods to fit.

Now thats out of the way... i need help knowing where to look, and who to turn to for custom rods. What type do i need? I beam? H beam? Will one clear the bottom of the sleeves/girdle better than the others? ERL suggests BC and Manley, but it would also be nice if i didnt have to drop $800 on rods.

I once saw there was a company that offered forged aftermarket rods for close to $400... but i dont remember if they were custom or shelf items... and i cant seem to find them again. Any help would be greatly appreciated...

- Dave

[bchaney]

I think H-beams are designed for boost because they're stronger. The downside is that they're heavier than the I-beams.

Can't make any recommendations on rod manufacturers but if you want good quality rods you're gonna pay more than what you would for the cheap chinese ones that everybody is selling.

[Ba82Ep3]

Coming from the 'old school' of boosting where it was assumed you could boost 8-10psi on a stock block, treat it decent, and get good life out of it... does rod quality come as a priority considering my intended use? Say the block only lasts 50k miles... did i toss $800 down the drain on rods?

I could reuse them in a similar build on a sleeved block if the unsleeved setup proves unreliable. Then i would be getting my $'s worth out of them.

My goal is to get as much performance per dollar value... but i guess i need to be sure i have rod strength to maximize that as well. Otherwise im possibly out a shortblock or worse, a head too.

Do you know if there is a way to know the difference between China and USA made rods... or is it just in who you choose to buy from?

Thanx again...

[bchaney]

I don't know too much about how boosted motors typically fail. I would look up common failure modes if I were building one. If rods / rod bolts are the weak spots, it mite be worth spending a little extra $ on for longevity.

You could always call the rod vendor and ask where the rods are manufactured. Typically those $400 rods are made in China but I would call before I ruled them out.

[talonXracer]

There are companies that have been making similar rods for several years now, Cunningham etc. Though they also use custom very short skirted pistons with the wrist pin intruding into the oil rings. I would follow that route rather than trying to use OEM pistons which will cause all sorts of issues.

[Ba82Ep3]

Ok, interesting thought. I hadnt thought about that. Ive noticed wear patterns on piston skirts in the past, and they seem to center around the upper middle (just above the centerline of the pin).

If the overall height (profile) of the piston is less (regardless of piston pin location), wouldnt that mean its more likely to chatter inside the cylinder? I would also think a tall piston profile would create more piston to wall friction as the stroke is increased (the piston seeing more lateral force), not to mention rod and skirt clearance issues.

Dammit. I didnt really wanna dig this deep into this... but it seems like custom rods and pistons would make the best of the situation...?

[talonXracer]

I would go an entirely different route, K24 block and a S2k crank with custom rods, far more potential.

[Ba82Ep3]

If i had the room in my EJ i would have kept my k24. That 19mm deckheight difference makes a significant change in oil pan/hood clearance for me (i live down an uneven gravel road). Some version of this setup would give me the best of both k20/24 worlds without excessive expense and more clearance.

Durability is a goal, but not an absolute neccessity. I have two engines so i can always swap one out for repairs with a spare to toss in... but i dont wanna rebuild an engine every 20k either. lol

[talonXracer]

The old IPS had a 2.2 that used a 2.0 block, but the A2 crank had the stroke lengthned by Castillo, custom rods by cunningham and custom pistons. The 2.4 crank is probably going to have too much stroke to even clear the rods/pistons in a 2.0 block.

[Ba82Ep3]

It looks like i could go:

86.5x92 or 94 for a solid 2.2L. But that involves almost 4 grand in hardware...

[Ba82Ep3]

Keep it comin... just throw out what ya find/think as a collective for info... ill be reading and researching everything.

[sleepy ep3]

I would get a block that's made for the displacement. There are so many variables when stroking out a 2 ltr to a 2.4, that by making the choice to go this route, you are making it that much hard and more expensive to find parts and parts that will work. If you are dead set on making it work, buy carillo. Just because you "have another motor" doesn't mean it's easy to take them in and out, or worth dumping money into one motor, having it go bad, then having to use the spare. The extra height in a k24 is there for a reason. Even though it's not a lot to talk about, 19mm difference is huge when you are dealing with clearances. The type of piston you are going to have to get, will need an incredibly short skirt, in order to not gouge and bind up against the cylinder wall on the upstroke. The k24 crank is going to be pulling the piston much further down in the cylinder, and if you don't have that extra 19mm down there, it could get a little strange in a hurry. The setup you have is very similar to an s2000 build they did at the shop. 2.0 bored and stroked to 2.4-2.5. It was built using the best parts, cp, carillo, and assembled by inline pro. He ran into the issue that I spoke about, due to the piston skirt being too long, and the block being too short. Kaboom. $25k build down the drain. I would just find a k24 block, and use that. They are not expensive, and since you don't plan on running a high rpm anyway, why bother using the 2.0 block and "making it work"?

[Ba82Ep3]

Yeah im seeing that... the more i look and read its still a 4k build at the 'cheapest'. It seems most k20 stroker cranks stop at 96, with 92 and 94 from Inline... and prolly for that very reason (skirt/rod clearance).

What did Honda do for the Mugen 2.2? Was it 86x96? Or did they go bigger on the bore? (searching...)

And as far as swappin out engines... thats a walk in the park for me. I have had this one in and out of the EJ three times for placement/fitment... and i used to drop the trans or engine out of my EP quite often. Again, this is a full on hobby for me... so i LIKE doin the work. :thumbu:

Kinda sucks cause i got rid of my perfectly good k24. Ugh...

[Ba82Ep3]

The 2.2 concept specs:

2,157 cc (2.157 L; 131.6 cu in) (87.0 mm (3.43 in) x 90.7 mm (3.57 in)) 11.1 260 PS (190 kW; 260 hp) @8250 237 N·m (175 lb·ft) @6750 8400

So an 86.5x92 should be doable then...

[talonXracer]

I would get a block that's made for the displacement. There are so many variables when stroking out a 2 ltr to a 2.4, that by making the choice to go this route, you are making it that much hard and more expensive to find parts and parts that will work. If you are dead set on making it work, buy carillo. Just because you "have another motor" doesn't mean it's easy to take them in and out, or worth dumping money into one motor, having it go bad, then having to use the spare. The extra height in a k24 is there for a reason. Even though it's not a lot to talk about, 19mm difference is huge when you are dealing with clearances. The type of piston you are going to have to get, will need an incredibly short skirt, in order to not gouge and bind up against the cylinder wall on the upstroke. The k24 crank is going to be pulling the piston much further down in the cylinder, and if you don't have that extra 19mm down there, it could get a little strange in a hurry. The setup you have is very similar to an s2000 build they did at the shop. 2.0 bored and stroked to 2.4-2.5. It was built using the best parts, cp, carillo, and assembled by inline pro. He ran into the issue that I spoke about, due to the piston skirt being too long, and the block being too short. Kaboom. $25k build down the drain. I would just find a k24 block, and use that. They are not expensive, and since you don't plan on running a high rpm anyway, why bother using the 2.0 block and "making it work"?

The stroke difference is 13mm, not 19mm, that is the block height difference, two completely different things. I have yet to see any K20 block capable of 2.4-2.5 displacement, it is physically impossible to gain that much in the bore and stroke