Forged piston brands

[nimblestix]

So im going to build my engine i think. Currently im running 400 awhp.

Some say the stock con rods are fine but im just going to upgrade rods and pistons plus all bearings and hardware.

So i dont want to go extreme with something like the tomei kit as im only ever planning on a max of 450awhp.

So im looking at either the cp kit or the weisco kit.
Im looking at the eagle rods at the moment.

Both these piston kits are very closely priced which brings me to the forum.
Are there any reasons to go with one brand over the other? and would any of you suggest a different con rod setup that is near priced to the eagle rods?

for the record ive priced approx a total of $1200-$1300 for pistons and rods + all acl and arp hardware.

As you can tell im only looking to make my bottom end reliable.
This is the start to a new beginning with my car. This is also going to be my first time ever rebuilding the bottom of an engine!

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[gtrjon]

http://forums.gtrcanada.com/gt-r-tech/45085-cp-je-weisco-pistons.html

exact same pretty much
what i got out of it was it comes down to preference. whatever helps you sleep at night lol

[R32GT-R]

if you have a little more budget the best setup for a rb26 would be.

Mahle slipper skirt pistons
carrillo A beam rods

super light rotating assy, matched with a full counter crank. it would be insane

[gtrjon]

if you have a little more budget the best setup for a rb26 would be.

Mahle slipper skirt pistons
carrillo A beam rods

super light rotating assy, matched with a full counter crank. it would be insane

thats easily 5k more than his budget tho. and a little over kill for 450awhp. carrillo A beam rods are gangster tho.

[Dragon Humper]

Yikes, totally over kill, hell the crank alone is $4000 if you get it for a steal. Eagle rods and JEs and you can't go wrong. A lot of builds have made 700+HP with nothing but......a lot have fried with much more expensive parts, its all in the machining and assembly.

With that low of a goal all you need is pistons, the stock rods are good to 600 at the crank with prep and ARP rod bolts.



Jon.

[christdeyoung]

A lot of builds have made 700+HP with nothing but......a lot have fried with much more expensive parts, its all in the machining and assembly

ie: Set your piston to wall clearances on the loose side. You might lose a little bit of power, but you can always up the boost to counter that if you end up losing too much. It just gives you more room for safety when shyte gets hot so you don't scuff.

If I recall, mine are set to more than double the upper limit in the service manual and I get hardly any piston slap and very little blow by. It recommends 1.4 to 2.2 thou, and mine are set to 4.5.

An aftermarket crank dampener would also be a good idea if you're changing to a heavier set of connecting rods.

[nimblestix]

ie: Set your piston to wall clearances on the loose side. You might lose a little bit of power, but you can always up the boost to counter that if you end up losing too much. It just gives you more room for safety when shyte gets hot so you don't scuff.

If I recall, mine are set to more than double the upper limit in the service manual and I get hardly any piston slap and very little blow by. It recommends 1.4 to 2.2 thou, and mine are set to 4.5.

An aftermarket crank dampener would also be a good idea if you're changing to a heavier set of connecting rods.

I never thought about the weight of the rods....a torque Dampener is a very good idea! Quick question now though. Seeing as the forged rods will be heavier, is that going to effect my rpm speed, like for example a stock flywheel would over a lightened one?
thanks for the advice! Im glad ive got something to start with.
I wont be building a loose engine because i wont be needing the extra clearence for the hp goals i have. If i was going to build in the 600+ hp range then that would be a different story.
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[Dragon Humper]

You should always build it loose. Don't go hog wild, but just over the factory limits for tolerance.

Why?

Because the factory must meet emissions targets and make a vehicle that you can just startup and go with no warm up time they must make it tighter than they really should (especially an engine that can rev like this one). I'll bet that every cooked rod, main and thrust brg can be traced to a clearance that was too tight. You need good oil flow through these areas to keep them cool while you rev the piss out of her. The thrust is where most machine shops screwup, some just can't bring themselves to sand the thrust surface of the brg to increase the space if it is too tight.

And to answer your other questions, a crank dampener is a very good idea (ATI) , not too often that aftermarket rods and pistons will weight more than stock, so no worries. If for some reason you actually went heavier you would have to add MalloryMetal to the crank to balance it (both a pita and expensive).



Jon.

[Skym]

From what I understand, stock bearings can fail due to excessive heat (I assume high oiltemps) and have no coating on them, Nismo mention it here (Nismo bearings are coated) -

http://www.nismo.co.jp/en/products/competition/engine/rb26dett.html#metal

You can get bearings coated before using them -

http://www.calicocoatings.com/

Or due to using wrong oil for oiltemps, thus oil is too thick and fails to get to bearing surfaces at higher rpm thus causing bearing failure and can close clearances on pistons rings (engine feels sluggish, struggles to idle, etc). Also engine oilcooler helps to keep oiltemps under control.

From what I understand, it usually takes out the ringlands on 3 of the 6 pistons if running too much boost, cracks block (I assume excessive cylinder temps due to lean A/F ratio with ECU tune, etc vs cooler coolant temps, harmonics cracks block and probably clearance issues with incorrect oil, etc doesn't help the ringlands on pistons + knock if it happens due to higher cylinder temps, incorrect sparkplugs, etc, doesn't help the ringlands), hence the switch to forged pistons with stronger ringlands, etc. Also from research into subject of forged pistons, they seem to have a slower expansion rate than stock cast pistons and I gather is why a forged engine needs to be warmed up before driving. Some forged pistons have cooling channels which help to keep piston temps under control (Tomei, etc pistons).

If run E85 which has a cooling effect, can run higher boost levels with stock pistons and run more aggressive ECU tune due to higher resistance to knock. So I gather fuel used plays a role.

As long as you set peak hp at lower rpm (roughly 1000rpm below redline) and increase boost level to make up for lack of revs (bonus of having a turbocharged engine), stock I beam conrods should be ok due to less inertial load on them. It's the conrod bolts that fail at high hp levels, rpm (Tomei, ARP, etc are the upgrade).

The bonus of lighter internals (forged pistons) is to reduce the inertial load at same rpm on conrods. Even H beam conrods can snap if you rev engine enough. Just 1000rpm more than factory is like adding 3 tons of inertial load to conrods (not actual figures, but you get the idea).

Only custom titanium conrods are strong, light enough and they cost alot -

http://www.pauter.com/titanium.htm

[gezed]

Actually I think eagle rods are 495grams compared to the 640g oem rods, thats 145grams weight saved per rod, also wiseco pistons thats half thou over are 343grams over the ~475gram oem, so you are looking at a weight saving of around 1.6kg in total off the rotating assembly. I dont think you can go wrong with that setup and itll rev like crazy!

OP just curious where you got the price 1200-1300 for pistons rods acl and arp hardwares cause ive been looking at these parts too and lowest i could price it to is around 1500(including shipping)

[christdeyoung]

I wouldn't waste the money on rods for your power goals anyway. Pistons, new bearings, and rod bolts as mentioned earlier.

[nimblestix]

Actually I think eagle rods are 495grams compared to the 640g oem rods, thats 145grams weight saved per rod, also wiseco pistons thats half thou over are 343grams over the ~475gram oem, so you are looking at a weight saving of around 1.6kg in total off the rotating assembly. I dont think you can go wrong with that setup and itll rev like crazy!

OP just curious where you got the price 1200-1300 for pistons rods acl and arp hardwares cause ive been looking at these parts too and lowest i could price it to is around 1500(including shipping)

Sorry i didnt specify very clearly. I meant 1200-1300 for pistons and rods only and then (+) for the hardware/bearings
So about 1500-1700 for the whole works is more realistic.
Just found on ebay that alot of people are selling pistons and rods and hardware as a package deal. Prices seem to be fair too! + most offer free shipping.
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[nimblestix]

I wouldn't waste the money on rods for your power goals anyway. Pistons, new bearings, and rod bolts as mentioned earlier.

Im getting the rods because compared to murphy's law they're cheap!

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