LS Rods - Type R pistons

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I’ve tried the search but theres too many keywords.

I’m planning on running Type R Pistons in a LS motor…I was reading and now I’m confused.

I know that there is a 2mm difference between LS Rods and VTEC Motor Rods, so I have the machine shop take 1mm off of each side of my stock LS Rods-No problem, I understand that.

My Question is:
Do I have to modify the piston to add a snap (Cosworth) ring to keep the Pin in place?

And If I do how much does a Machine shop typically charge for such a service?

Thanks
Travis

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When I had my Type R Pistons put on my rods, all they had to do was to modify the rods and everything else was fine…

But I had used ITR pistons…

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Max,

Thanks,

Thats what I wanted to hear. I think that the JDM ITR and USDM ITR Pistons are probably close enough that for all intents and purposes are equal. You are running USDM P73’s Right?

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I have 0.25 over CTR’s on my LS rods. The machine shop actually machined the piston, not the rod. The rotating ass’y was then balanced.

Just another option for you.

Adam

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im considering this also but a local import mechanic wiz (former honda tech) said that you can’t use an ls head and then use ls rods and itr pistons he said this always also leading to valve to piston contact and cylinder failure…; thoughts?

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Well, my setup consists of Ls rods, CTR pistons (much bigger dome that ITR pistons) and an LS head.

The motor isn’t installed yet, but I’m planning on claying it just in case.

I’m not worried about piston to valve clearance even with high lift cams.

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Well, if you can use a P72 head with PCT pistons, then logic suggests that the PR4 head, with its 45cc combustion chambers (much larger than the P72), isn’t going to have any clearence issues at all when used with PCT, P73-OO or P73-AO pistons. Of course, the lofty PCTs will require a bit more attention to detail while tuning.

The valve relief cuts on these pistons are designed for the larger valves in VTEC heads and higher lift VTEC lobes, so again, I would think you won’t have any problems if you’re not using a cam that is bigger than a Crower 404 or so. Piston to deck height is also the same with all B18A/B/C blocks, too.

You might have problems using a VTEC head on a LS block with high lift cams, PR4 pistons and shitty tuning. Thats the only situation where I can see a huge problem.

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hey I am thinking of running usdm type r pistons in my car or jdm pistons. But if i do would i have to buy new rods or get the ls rods worked on. Also does any one know what there comprassion is on there motor with type-r pistons

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kinda ot: Its only ls rods that need to be machined to fit itr pistons right? They’d just pop right onto b16a rods right?

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No B series pistons uses a floating wrist pin. All use a pressed in wrist pin.

B16A/B17 rods are in the same family as the B18A/B and B20 rods. All would need to be milled 1mm per side to fit the P73 or PCT pistons. You can also have the pistons milled, which I think is a better idea.

All B16A/B17/B18A/B20 rods need to be machined to accept any “R” piston.

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JDMDA9 knows his shit. :up:

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Originally posted by KraZEtEggIE
ok if u say so… :gay: lol. just relayin info. explain y the hell they would make the rod SMALLER? do you really think they would make the rods 2mm thinner for the highest hp b-series engine they made?
ALSO WTF ARE YOU TALKING ABOUT? I HAVE USDM ITR PISTONS ON LS RODS. NO MODS NEEDED. I SWARE I HATE PPL WHO TALK OUTA THEIR ASS. QUIT WHILE U THINK UR AHEAD!
what setup are you running since u are talking 1st hand experiences?

I posted this before I bought my pistons. Now after I have them in my hand and measure them I can certinly tell you that the LS Rods do NOT just fit into the Type R pistons. I might be able to get a 50 ton press and completely destroy my pistons to get my rods in there. I don’t know about P73’s but I can personally tell you that they do NOT fit without modification.

PR4 Rod - .786 (little end)
PR4 Piston - .895
Clearance of .109

Piston - .778
PR4 Rod - .786 (little end)
Interference of .008

Also I’d rather mil my $20 rod than my $50 Piston.

I hate people who just relay information without knowing what they are talking about. :mad: Go drive your 3rd Gen…Oh it’s an F-Body.

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ITR pistons do not fit on LS rods without modifications. I just did this, and as stated about 1/16" has to be shaved from each side of the small bore end of the rod. Same goes for CTR pistons.

And there is NO DEBATING THAT FACT.

IF you like I’ll post pics for you.

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lol.

HE is talking about LS rods on ITR PISTONS!!!

Pistons do not FIT DIRECTLY on the/ANY crank.

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If you stop and think for one second you’ll realize that the chance of breaking a rod at the top is very small. The maximum bending moment is towards the center especially when you consider that the Rod is not at 90 degrees. Something about cross sectional area and total load bearing capacity. This rod was hydrolocked, which I beleive is more force than one will ever apply in normal driving.

I’m still waiting on a measurement of USDM Type R Pistons.

It’s a shame that the 3rd Gen F-body with a 305 V-8 can still be outrun by a stock Ford Taurus.