he did the work last time and I ve known the guy for a while I know that he will do whats needed if I tell him to ( he builds mostly domestic cars but did work as a machinist for a Honda dealership some time ago)


since the block took a dump on me im thinking about doing some different parts

1 bore it out to 82mm from 81.5
2 supertech forged pistons to yeld 12.5 compression for pro 1 cams instead of cast pr3 pistons

3 have the crank balanced to high rpm without bob weights like he did last time(I didn't know and he did what he usually does)

4 have the pistons and rods weighted ( how do you weigh the rods do you put them on 2 scales to weigh the rod ends


5 should I tell him to machine the rods and mains to try to accept same size bearings?
I had one rod bearing and 2 main bearings smaller than others from factory

6 I cant find the thread anymore but it talked about properly machining the cylinder walls that have to be tighter towards the top of the cylinder bore and bigger towards the bottom( I forgot the terminology here sorry)

7 doesn supertech specify what p2w clearance should be for their forged pistons?

 

2. forged pistons but not forged rods?
5. NO ABSOLUTELY NOT. Honda made these engines with very tight clerances and as long as everything is still round like they should, just stick with oem bearings, mismatch and all.
6. oem service spec is .002in taper meaning the maximum is .002in top to bottom. you want zero taper in a perfect world.
7. yes, they should include a sheet with all the specs needed.


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well there seems to be some confusion then

00red sir said that gsr rods are forged and theres no need to upgrade on street setup. forged pistons just give be specific compression ratio and bore size that is not available in OEM casting pistons.


there was an argument about that here somewhere but I cant remember the outcome
someone said the cylinders should have a slight taper bore to seal the rings beter at TDC.


and by machining for clearances I meant the big rod ends so that they can accept bigger bearing one size bigger to be exact( one of the rods is smaller than others)

and 2 of the mains are smaller bearings than others

I know crank bearing surface is hardened but can the mains be machined on the block?

 

4. The shop should know how to weigh each rod and piston by themselves and get them as close to even as possible. Then they will assemble and check again and then make whatever adjustments.


I have read where alot of domestic machine shops have really fuct up honda engines by not following Hondas guidelines and using their own.

I would ask the shop how many Honda blocks have they done and are they familiar with honda's guidelines.

 

I took my bore taper information straight from the factory service manual, which again, stated the maximum service limit is .002in honda blocks require zero taper to get a good seal.

as for boring the mains, I would never touch them unless they were out of round. same goes for resizing the rods, I wouldnt do it either for the same reason. its not worth the hassle or burnt money to do such a thing.

and I dont believe any stock rods were forged. gsr rods are stronger because they have bigger rod bolts, thats it. unless someone else has differing info, if you get forged pistons, get aftermarket forged rods.


Posted from Honda-tech.com App for Android

 

by the way, take a look at a bearing size chart. the amount of change you want is like splitting hairs. you could end up making things worse by trying to do what youre saying


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Well, if ARP rod bolts are used on OEM rods, they will need to be re-sized..

You can also shot peen the rods for strength, but good luck finding a shop that does this.

Going to a lighter rod means the whole crank will have to either be knife edged or cut to balance for the lighter rods/pistons. This is why I stayed with OEM pistons and rods to cut down on machine shop cost, and a little cheaper to not have to purchase new pistons and rods. Cast pistons are fine for NA and Rods are fine for NA. Ive seen B18/20 rods in boosted applications hold up, so NA is OK.

Just my .02

 

Changing piston/rod weight has no impact on the crank counterweights on our 4cyl engines.

Desired RPM will dictate rod choice more than HP on an NA build, a Pro1 cam motor should be good with OEM rods.

 

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/p-r-e-stock-sleeve-b20vtec-dyno-3164743/

stock rods with arp bolts and 9500 rpm

 

putting arp rod bolts puts the rods out of round by increasing the clamping force so of course they need to be resized.

but what he wants to do is take a perfectly fine, in spec rod, and hone it out to use a one size larger oem bearing. imo this is not a good idea. why mess with something thats not broke


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this is kinda what im talking about every thread thres 10 people saying completely opposite things. how the hell do I know whats the correct info...



easier to order bearings.(green bearings to be specific) i thought i ve seen some places sell them as a package.


im changing because of the compression ratio not available in stock casting pistons. and i red that supertech pistons are pretty good quality(im using RS machines now)


if the pistons dictated weight then jdm engines would have different crank

its crank is heavier so are the pistons, but the rods are lighter and so is flywheel ( the rotating assembly ends up being same weight i belive as gsr)

 

flywheel doesnt really mean much to the rotating assembly. piston weight, rod ratio, and rev limit are what matters most. heavy pistons with short rods have a massive amount of gforce and can destroy an engine if revved too high. the same pistons with longer rods would see a less sudden change in direction and can rev higher safely.

thats why for the gsr engine you have a slightly lower stroke, and longer rods.

mean piston speed I think is the term im looking for.

as for bearings, why not just order oem bearings from acuraoem? unless price is some sort of an issue (about 10 bucks per half)




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1. Not bored, honed. Those are two different processes. 81.5mm to 82mm isn't a lot of material to remove so there is no need to pay the additional $200-300.

2. Forged pistons are good. They tolerate a lot more abuse than cast pistons, just need to be sure to get the clearances correct, both piston to wall and piston pin clearance as well.

3. If it was balanced once without bobweights, it probably doesn't need to be balanced again. The weights of the rotating assembly do not need to be factored into the crank balancing.

4. The rods are weighed on one scale, but a stand is used to measure one end at a time. I'm sure you can find a picture if you google it. The stand will hold one end, either the small or big end, while the other end is on the scale. Once you measure one end, flip it around and the other end is measured.

5. I prefer to cut the crank rather than hone out the bores. The reason is that the bearing ID is larger than the ID of the rod and main bores so there is a press fit when everything is torqued. This press fit keeps the bearings in place and keeps them from spinning in the bores. Opening up the ID of the bores reduces this press fit. I cut the crank to get the clearances I want instead, it is much much easier. I measure the ID of the bearings with everything torqued, and then have my crank grinder remove just enough material to give me the exact clearance I desire. Barely any material is ever remove, so the surface hardening is not effected, and the grinding ensures the journals are perfectly straight and round. I've fixed a 700whp Nissan this way after the thrust was burned up and bent the crank .002". The journals were machined .010" undersized with the correct bearings and had a happy life after that.

6. Horrible advice. Taper will cause unnecessary fatigue in the rings. For every .001" of taper, the rings will have to flex .003" (times pi) to conform to the cylinder. Think of bending a paper clip back and forth until it breaks. Same thing will happen, but the rings don't break, they just loose tension and their ability to seal. The bores should be straight, not tapered. A competent machinist should be able to get the bore taper under .0005", anywhere near .002" is embarrassing or something went wrong somewhere. Find a place with a torque plate if you can.

7. The manufacturer does specify their recommended PTW clearance, but you can run looser if the application requires it. Most naturally aspirated combos can just follow the manufacturers specs and be okay. Big power (big heat) will need more, though.

If a domestic machine shop screws up an import engine, they probably aren't very good at machining domestic engines either. Then again, machine shops get a lot of the blame when anything goes wrong, regardless of who is really at fault.

 

f yea i blame my machine shop for everything even before they do the work i already know what to blame them for

about the crank i meant the rotational mass of the flywheel and crank for its in the end is close to gsr. when people say itr crank is heavier and they don't like it...

 

They say they don't like it because of the way it looks on paper. no experience. Put that same person in a car with either a GS-R or Type R, and even on the dyno won't know the difference.

I do agree with the following comments, so If they don't mind, I'll reiterate those that stated it instead of starting from scratch



" Forged pistons are good. They tolerate a lot more abuse than cast pistons, just need to be sure to get the clearances correct, both piston to wall and piston pin clearance as well. " -EG1834

If this machine shop is of any good repute, you don't need to tell them specifics on the balancing of the rotating assembly, as the standard process should be to have the piston/rods together balanced and "hung" (meaning weighed), and balanced with simply the clutch and flywheel together, if you can. If you don't have them at the time, its of no consequence. Just don't overcomplicate the process ... Like I PM'd you, let these guys do their job.

As stated..
"flywheel doesnt really mean much to the rotating assembly. piston weight, rod ratio, and rev limit are what matters most. heavy pistons with short rods have a massive amount of gforce and can destroy an engine if revved too high. the same pistons with longer rods would see a less sudden change in direction and can rev higher safely. " -m4xwellmurd3r

"putting arp rod bolts puts the rods out of round by increasing the clamping force so of course they need to be resized.

but what he wants to do is take a perfectly fine, in spec rod, and hone it out to use a one size larger oem bearing. imo this is not a good idea. why mess with something thats not broke" . -m4xwellmurd3r

"6. Horrible advice. Taper will cause unnecessary fatigue in the rings. For every .001" of taper, the rings will have to flex .003" (times pi) to conform to the cylinder. Think of bending a paper clip back and forth until it breaks. Same thing will happen, but the rings don't break, they just loose tension and their ability to seal. The bores should be straight, not tapered. A competent machinist should be able to get the bore taper under .0005", anywhere near .002" is embarrassing or something went wrong somewhere. Find a place with a torque plate if you can." -EG1834


We typically have the OEM rods shot-peened for strength (Perhaps its where we are but it is a very common practice) when going with Forged Pistons. Its the best idea all around, then use the newer sizes with OEM bearings, (sized individually and accordingly) not just one size.


Again, as we discussed. Stop telling the machine shop how to do their job in their arena. If they don't know what they're doing with imports, they don't know what they're doing with any other engine.. An engine, is an engine, is an engine, unless its a boxer, then its just a PITA.

 

^^

Im in that list.. indirectly