Stock pistons "rate ore hate" ?

[Fricke]

Originally Posted by Matt@Cosworth

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

Exactly, but if you want a really responsive engine on acceptable hp goals, why change too forged Pistons whit 12.5:1 if the oem piston holds up for the task

[Fricke]

Originally Posted by sales@delicioustuning.com

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.

Sincerely,

Zach
Delicious Tuning

Seams like seriously horsepower on that compression, butt if it works, it definitely work
But that's not on stock Pistons I guess.
Personally I don't have to go over 350whp, I think that will do it for me

[Fricke]

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.

[blueap2]

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.

[Spartarus]

Originally Posted by Fricke

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.

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.

Originally Posted by spitfire481

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

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

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.

Originally Posted by blueap2

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.

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.

[seito23]

I would replace the stock pistons if I was having work done. Admittedly , I haven't seen anywhere that pistons are a common failure point. Pistons may become the weakest link, if, everything else is upgraded. On the off chance that a piston lets go and destroys all the other engine work, that would be tragic.

P.s. when I do have the motor built, it will most likely be at stock compression or close to

[Fricke]

Originally Posted by Spartarus

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.

Didn't think of specify everything on the car to this day, but the fact is that the car has already gone through som changes, and has competed in Swedish Timeattack Club class 2015 and took a 3rd place, and for 2016 it will run that same class again, but my goal is too goo up a class 2017 because the car is too under powerd in club right now
Going up against 2-3 Porsche Cayman S, Porsche 993 C2, Ford Focus RS, Evo x, imprezas, and so on.
But will do my best and then some.

Mod list too this date..........
https://www.facebook.com/F.Wernboe/
The Perrin oilcooler is on the car, djust forgot to mention it in the description.
I'm also running Agip I cint 5w40 and change oil and filter after each race weekend.

The clutch will be upgraded from the exedy stage 1 to somethings better.
But valve springs I will change anyway, do it doesn't seem like a bad idea on a motor going FI on high rpms most of the time, so that I don't get floating and break a rocker or valve.

[Kodename47]

Based on what others have said before, it might be worth checking the OEM pistons and smoothing off any sharp edges if there are any as it will help with knock resistance. The same was mentioned by @Matt@Cosworth about aftermarket pistons so I don't see why OEM would be any different. If you have the head off it might be worth looking at the DI injector area for the same thing although I would be cautious about this, I seem to remember Carolina Dyno saying that this was a potential area to increase knock sensitivity,

[wparsons]

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).

[makinen]

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.




But Skunk2 rods have this shape.


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

[seito23]

Originally Posted by wparsons

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).

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

[Xero-Limit]

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.

[justinsstang]

Originally Posted by moto-mike

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.

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

[makinen]

Originally Posted by moto-mike

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.

I agree that using forged rods with stock pistons is pointless. But it happened.

I planned not to exceed the power level that the stock rods failed. I only want to make the big ends kept the shape more than the stock. I've prepared King's bearings also.

For the machining of small ends, the stock one also machined as I observed. Here is an example video that machining similar way (don't know my case is the same or not.)