Originally Posted by Fricke (Post 2552060)

Going Supercharged next race season (2017) and of course i want a forged bottom end.
But planing on keep the stock compression ratio, and that's were my thoughts wonder of :iono:
Why spend money on something that's seem to do the job?
Is there even any of you in here that have suffered from blown pistons on FI? (Don't mean NASA astronomical hp outputs now)
Why just don't get forged rods, gasket set and bearings and go whit oem pistons, the car wouldn't go past what a HKS V3 or Jackson kit deliver on E85 anyway.

Originally Posted by go_a_way1 (Post 2552070)

Well if your already in there, may as well replace them :iono:

Originally Posted by Spartarus (Post 2553063)

Pistons need to come out to change rods. There are no wrist pin access holes like the ej series. Not a big deal but just letting you know.

Stock pistons will give up around the wrist pin if they do fail, but you should be fine on non-astronomical power levels.

Few people have lifted the heads somewhere in the vicinity of 400. ARP fasteners and all that are a no-brainer on any build.

Originally Posted by spitfire481 (Post 2553064)

when you remove the pistons and rings, they will not be in the exact same orientation that they mated to the bore in when you install again.

Originally Posted by Matt@Cosworth (Post 2553070)

the main thing with changing the pistons is that it allows you to drop the compression ratio which is very necessary for big power builds but otherwise I'd agree the stock item is well made and not the weak link of this engine

Originally Posted by sales@delicioustuning.com (Post 2553193)

I don't see anything wrong with stock compression on big power builds. We've got folks running forged 12.5:1 compression pistons with over 600whp. :iono:

Sincerely,

Zach
Delicious Tuning

Originally Posted by Fricke (Post 2553303)

So that seems to me, that my shopping list should be like this.
Rods
Bearings
Gaskets
Head studs
Valve springs
And maybe oil pump?
Are Cosworth offering any blue printed beefed up pumps jet? Like the ones you always included in the EJ builds, don't think it's a bad aide att tracking, but maybe the oil pumps are better att FA? Haven't looked in to that so much.

Originally Posted by spitfire481 (Post 2553064)

when you remove the pistons and rings, they will not be in the exact same orientation that they mated to the bore in when you install again.

Originally Posted by Fricke (Post 2553280)

Piston rings are not locked down and are freely to rotate on the piston...

Originally Posted by blueap2 (Post 2553327)

Honestly for 350whp ish, I don't think you will need:

Gaskets, head studs, valve springs, and an upgraded oil pump unless you plan to raise the stock redline.

If you plan on tracking you MUST HAVE an oil cooler. Our engines run pretty hot stock so with all the added power you need an oil cooler.

Originally Posted by Spartarus (Post 2553371)

There isn't a beefed-up oil pump. The oil pump housing is cast into the timing chain cover, meaning you can't change much about it. Reimax makes a forged gerotor which should displace significantly more oil, but that calculation is untested. Nobody has reported problems with them though, could be worth it considering the oil pressure issues this engine suffers. That said, many people have been just fine on the stock pump.

Everything else looks fine.

Main Bearings and valvesprings are overkill, but King bearings makes an alternative to OEM if you do decide to split the case. You'll need new rod bearings for the new rods regardless.




Both are correct. The practical consideration is simple. You will need to follow an appropriate break-in procedure to ensure the rings seat properly anytime you pull pistons in and out. That is what we do with reciprocating airplane engines, and we build them to make max power for more than 2000 hours. It'll work just fine for car engines. Resurfacing the bore and replacing the rings on a low hour engine is overkill.



I agree valve springs are unnecessary. I disagree with everything else. The heads have to come off to replace the rods, because the pistons need to come out. The head bolts torque-to-yield and are not reusable, so you need to replace them anyway. Studs are not expensive. Gaskets are also not reusable, therefore they stay on the shopping list as well...

I also agree that an oil cooler is imperative. Any kit with an air-oil heat exchanger. The coolant-based heat exchangers are massively insufficient for high-power applications.


I noticed a clutch is missing form this list. That will be necessary.

Originally Posted by wparsons (Post 2553852)

If the car is a pure track car, and you don't mind hearing piston slap when it's cold, then forged pistons are fine. If it's a street car and sees cold weather use, the piston slap from forged pistons (until they heat up and expand) could get really annoying. I know a couple people that put in forged pistons and regret the decision.

For your power levels, I would only replace things that you know are failure prone or are single use items (gaskets, studs, etc).

Originally Posted by moto-mike (Post 2555276)

It makes no sense to use the stock pistons with an aftermarket rod. The pistons fail right around the same HP level the rods do.....

Then there's the problem of fitting the small end of the rod into the stock piston--bad idea to machine them. You'll be hammering on the wrist pin bushing with that end mill during the process. BAD idea.

Last year we did a motor for someone and we tried to use the stock pistons only to discover the rods don't fit without a good deal of work. In that case we used CP off the shelf 10.5:1 that don't cost a whole heck of a lot. Driving it after the fact even NA? Not a huge difference in power. Maybe 10-15 hp or so, but with the ability to run crappier gas and much more boost. If you get the high boost pulley with any of the SC kits you'll more than make up for the slight loss of compression, but gain a whole lot more reliability. Stock pistons are hypereutectic and don't expand a whole lot, but they still expand and run tight end gaps. Get hot on track with them and it's bad news. A forged piston with 3.5-4 thousands clearance will do much better on track with a .017-.018 top ring gap, and has zero piston slap hot or cold on the FA20. Every motor we've put in the last few months has run just that, and you'll be hard pressed to tell it isn't stock when you fire it up.

Originally Posted by moto-mike (Post 2555276)

It makes no sense to use the stock pistons with an aftermarket rod. The pistons fail right around the same HP level the rods do.....

Then there's the problem of fitting the small end of the rod into the stock piston--bad idea to machine them. You'll be hammering on the wrist pin bushing with that end mill during the process. BAD idea.

Originally Posted by seito23 (Post 2555127)

Are the tolerances really so tight? I am in Florida, so, maybe not an issue. With new rings and a honed wall I am surprised a little

Originally Posted by makinen (Post 2554839)

I'm on the almost same boat.
My list is,
Skunk2 rods
King's bearings
ARP head studs
Reimax oil pump gear
Main case bolts
Gasket set
GSC single valve spring kit.

One thing I have missed is thr tapered small end of stock rods and matched stock piston pin area.

Attachment 131637
Attachment 131638

But Skunk2 rods have this shape.
Attachment 131639

So I have to go to the machine shop to match the stock pistons.
Attachment 131640

Originally Posted by wparsons (Post 2555473)

Forged pistons run smaller when cold, that's why they slap. Once up to temp they expand and fill the space better.

Originally Posted by wparsons (Post 2555473)

Forged pistons run smaller when cold, that's why they slap. Once up to temp they expand and fill the space better.

Originally Posted by Fricke (Post 2555637)

that was a ripoff :(
I can understand why ( more material ) but is all the forged Pistons and rods that way, or is it heads up an be ceer full whit what Pistons and rods you buying, so that they match?

Originally Posted by justinsstang (Post 2555373)

How much are the CP 10.5:1 you're talking about? I was thinking about going 11.0:1 when I build it, not sure the price difference between the two

Originally Posted by seito23 (Post 2555644)

I was thinking of it like, Mike, from Moto East. A piston that has been given the proper tolerances shouldn't slap anything, except the competition.

If that is common place to get piston slap after building an engine, me personally, I would think twice about having a build done in the first place. I am building the motor to make sure it lasts and can withstand the extra punishment that naughty engine deserves :burn rubber:

Originally Posted by moto-mike (Post 2555848)

Around 650 ish with rings. Factory rings cost 180 or so retail, so 470 is the cost difference when you factor that in.