BPG forged pistons vs aftermarket

[BSTD_B7]

Hey all, I think I’ve decided that while I have my engine out for a tear down & rebuild I’m going to go forged internals and Ferrea head components, who has a lot of research & experience into the BPG pistons? I have a BPG engine and confirmed upon disassembly that my pistons are the oddly shaped forged pistons, but I’m curious to know how much benefit aftermarket pistons are going to give me & if I should just dig up the extra $$ to get the aftermarket set. Anyone with knowledge/experience on this I’d love the input! Thanks!


Big Turbo B7
MK1 TT 225 Roadster

[Okedokey]

IIRC aftermarket con rods, wrist pins etc are where the best upgrades may be given you already have forged pistons.

[i3oricua]

I guess it depends on how far you plan on taking your power levels. I don't know what the failure point of our forged pistons are. I think you can safely get away with 400hp on them. I did anyways. The rods are the real weak point.

Edgar

[aluthman]

What are the plans for the car? Building the head is largely unnecessary for most setups.

[EvolutionArmory]

With aftermarket pistons you can tailor your CR to to suit the build and if you are making decent power you might want to drop it a little. You’ll be able to run more timing and boost sooner without timing correction. With stock pistons you’re stuck at 10.5:1.

Doing head work is probably unnecessary unless your rev limiter gets bumped up a good amount

[BSTD_B7]

Honestly the plan is to try to break the power ceiling that everyone seems to be hitting, the biggest set back with our platform seems to be fueling which is why I’m setting myself up to be able to run port injection in the future, this year though the goal is just to get the engine work done & replace every gasket & bushing on the car as well as lighten the load on the engine (balance shaft delete, lightweight flywheel, billet crank pulley, etc.) I will be driving the car in the summer a fair amount but I do have a daily backup so I’m not at all worried about comfort, I fully intend on making this a street driven car that I can put down a wild 1/4 mile time with at car shows, I know regardless of how much fuel & forged parts I put into it there is still a limit to power because there’s only so much air an engine can flow, and at some point I imagine the block would give out, but I’d like to see what I can do.


Big Turbo B7
MK1 TT 225 Roadster

[IronAudi]

If your goal is max power than I wouldn't leave stock parts in that have 100k miles and a billion heat cycles. IE sells ready to go engines with all the goodies, if your going to spend that kind of money, buy a 2nd engine and swap it in. Also a Tranny refresh might be in order, you wont come anywhere near the limit of the 01E with a 2 liter. Even if you over bore the 1 mil and E85 or better, 500whp is where Ive seen them stop. Garrets new G550\660 turbos are mean for 1.5-3L engines, that's where I would look for my new Turbo, everyone in the BMW world and Drifters really enjoy them

[aluthman]

With aftermarket pistons you can tailor your CR to to suit the build and if you are making decent power you might want to drop it a little. You’ll be able to run more timing and boost sooner without timing correction. With stock pistons you’re stuck at 10.5:1.

Doing head work is probably unnecessary unless your rev limiter gets bumped up a good amount

You can mill the crowns off the BPG pistons and be at ~9.5:1 CR. This will save you about $500.

That being said, if the goal is to shoot for the moon, an aftermarket set of 2618 alloy pistons is the route you want to take.

[i3oricua]

ARP also sells studs and bolts that are meant for really big power applications so you should look into that too and might as well drop those in instead of replacing all that stuff 2 or 3 times. I agree though that you should go with brand pistons meant for higher power but just a thought.

Edgar

[BSTD_B7]

I did get ARP fasteners already, I’m leaning towards the new piston route, however I’ve heard mixed stories about going oversized pistons on these engines so I’m probably going to go stock size, I heard the advantage of overbore is minimal on this engine, I plan to try and find the limit of the TD05H-R this year since it’s what I’m already running, and next year I’ll probably up to a garret setup when I go for port injection


Big Turbo B7
MK1 TT 225 Roadster

[BSTD_B7]

Sticking with stock sized parts valve guides are the one part that I’m unable to do myself due to lack of machinery, so I called my local engine shop, they said they can install & cut the new IE guides but are convinced that I’m not going to be able to lap the new valves and I’ll need to have the seats cut instead, anyone else have that experience?


Big Turbo B7
MK1 TT 225 Roadster

[EvolutionArmory]

Save yourself a big headache and just leave the head alone or at the most do an OEM refresh. That’s it. I doubt you’ll need any special head work with a TD05. Even with a strong tune from a competent company.

And keep in mind if you do ARP main bolts it’s recommended that you get the main caps line honed because of the increased clamping force. Some people say just send it without the line hone but it’s what ARP recommends

[vvenom800tt]

Just curious Evo, educate me on what a line hone is for the main caps?

Just trying to learn as i read here.

Thanks!

Save yourself a big headache and just leave the head alone or at the most do an OEM refresh. That’s it. I doubt you’ll need any special head work with a TD05. Even with a strong tune from a competent company.

And keep in mind if you do ARP main bolts it’s recommended that you get the main caps line honed because of the increased clamping force. Some people say just send it without the line hone but it’s what ARP recommends

Sent from my SM-G960U using Audizine mobile app

[BSTD_B7]

Save yourself a big headache and just leave the head alone or at the most do an OEM refresh. That’s it. I doubt you’ll need any special head work with a TD05. Even with a strong tune from a competent company.

And keep in mind if you do ARP main bolts it’s recommended that you get the main caps line honed because of the increased clamping force. Some people say just send it without the line hone but it’s what ARP recommends

Already ordered all of my parts yesterday so I’ll be doing the head build, the TD05 is only temporary, and I’ll be doing the tuning myself as scary as that is.. next year when I swap from 4 port meth to port injection I’ll probably also go with a different turbo, in the mean time it’ll be nice to have a fully built motor & not have to worry


Big Turbo B7
MK1 TT 225 Roadster

[EvolutionArmory]

So your main caps have a certain amount of flex when you torque them down. A line hone is done on the caps with them torqued down to make sure the area of the cap and block is still round under torque. If you use stock bolts torqued to spec, the flex will be the same as OEM when the motor was first assembled.

ARP fasteners are higher torque and aren’t flex bolts so it will flex the caps differently and might cause a high spot on the cap.

A line honing would hone the caps and block when they are torqued to final spec to keep them round.

Think of it like how new performance rods come shipped. The come shipped assembled because the manufacturer assembled them torqued to spec and honed them so they’re round when torqued.

[aluthman]

And keep in mind if you do ARP main bolts it’s recommended that you get the main caps line honed because of the increased clamping force. Some people say just send it without the line hone but it’s what ARP recommends

This is true, but I’ve built a couple motors with ARP studs now and none of them got line honed. I looked into it and it’s crazy expensive so I took my chances.

[EvolutionArmory]

Yeah, I’m sure a bunch of people have used them without line honing but the by the book method says you should.

I would be that one guy in a hundred who would get bit in the ass so I went with OEM main bolts just to be safe.


Sent from my iPhone using Audizine

[vvenom800tt]

Thanks for the explanation.

You're a wealth of knowledge!

So your main caps have a certain amount of flex when you torque them down. A line hone is done on the caps with them torqued down to make sure the area of the cap and block is still round under torque. If you use stock bolts torqued to spec, the flex will be the same as OEM when the motor was first assembled.

ARP fasteners are higher torque and aren’t flex bolts so it will flex the caps differently and might cause a high spot on the cap.

A line honing would hone the caps and block when they are torqued to final spec to keep them round.

Think of it like how new performance rods come shipped. The come shipped assembled because the manufacturer assembled them torqued to spec and honed them so they’re round when torqued.

Sent from my SM-G960U using Audizine mobile app