Forged Internals vs Stock for sub 400hp in a daily

[Tehnation]

Actually what are your mods???!!! That will help see where ur hp might be! What injectors are you running is probably the most important thing. 850cc+ and u can easily make 400whp on e85 from my recollection!

[Tehnation]

400whp on gas or on E85? On gas that is more than the stock pistons or gaskets are going to take.

 

 

 

I know two guys who have broken 4032 pistons and even though I considered using them once upon a time I now start shaking my head as soon as the number in mentioned in conversation. I've been running Manley 2618 pistons at the bottom of the recommended clearance range for about 40,000km now. I use no oil between changes and the sound of piston slap is only really apparent on a cold engine on a cold day, or on a warm engine at idle and with the a/c on. Then it sounds like a diesel. Otherwise it's pretty much as quiet as stock.

 

 

Clearance for bearings? If that's what you mean what are you running, i am curious because i am building my engine with 2618's as well. I was going to go slightly more than stock.

[Tehnation]

I hear a lot of people say 4032's are not much better than stock!!!

 

Either way... If you get a new block with same tune what do you think will happen? You will most likely need better rods, just from your own experience you should realize if you want to keep the same hp you had then you obviously need better rods and pistons.

 

an oem build at 400whp will not last 200k.... i don't know where you heard that. Does a stock oem engine even last that long lol!!!

Edited May 8, 2016 by Tehnation

[fahr_side]

Clearance for bearings? If that's what you mean what are you running, i am curious because i am building my engine with 2618's as well. I was going to go slightly more than stock.

No I meant piston to wall. On the bearings I went to the upper limit in the FSM.

[Tehnation]

ptw gotcha! good to know! so tight for pistons and loose for crank!? Edited May 8, 2016 by Tehnation

[fahr_side]

Manley's PTW specs work well, I just targeted the tight end of their suggested range.

 

 

Sent from a device using some software.

[xtea]

Manley's PTW specs work well, I just targeted the tight end of their suggested range.

 

 

Sent from a device using some software.

 

Was that for the graded drop ins?

[xtea]

I am not sure how the tune could've bent the rod. The rod wasnt bent when I drove it away. It could also be a spun bearing, they have not tore the motor apart yet. The assumption is rod or bearing based on the sound. I assumed the failure was bad mainenuence the first 100k.

[Tehnation]

no one understands how you could bend a rod without destroying a stock piston, but rods bend for a lot of reasons, i didn't think these engines were prone to bent rods!! But being that it wasn't actually pulled apart, everything is all theories at this point! Its probably a bearing or shattered piston. Edited May 8, 2016 by Tehnation

[Tehnation]

but from my experience rods bend from doing bad things, downshifting into incorrect gears which leads to overreving, or hydrolock.... either way its the tune/build or doing bad things... bending a rod is pretty hard to do with all things being optimal. Edited May 8, 2016 by Tehnation

[Tehnation]

I am not sure how the tune could've bent the rod. The rod wasnt bent when I drove it away. It could also be a spun bearing, they have not tore the motor apart yet. The assumption is rod or bearing based on the sound. I assumed the failure was bad mainenuence the first 100k.

 

detonation can bend a rod, which is due to tune.... or too much boost at low rpm.... due to tune

[xtea]

Woukd a bigger turbo like a dom 1.5 or 20g be better for our cars since they spool later and push the band to the right which is safer in terms of low rev/high load?

[fahr_side]

Was that for the graded drop ins?

I had to go to 99.75mm but the clearance tolerance range is the same for all diameters.

I am not sure how the tune could've bent the rod. The rod wasnt bent when I drove it away. It could also be a spun bearing, they have not tore the motor apart yet. The assumption is rod or bearing based on the sound. I assumed the failure was bad mainenuence the first 100k.

Well, let's see how it looks when it's opened up. You usually bend a rod from too much cylinder pressure at low revs, where overrevving leads to broken rods. A bent rod will usually result in one cylinder not firing at all, massive vibration, but not always strange noises.

Woukd a bigger turbo like a dom 1.5 or 20g be better for our cars since they spool later and push the band to the right which is safer in terms of low rev/high load?

Yes, that's safer in terms of avoiding bent rods.

Edited May 9, 2016 by fahr_side

[shralp]

Good information here for you to chew on Xtea. As for the debate between 4032 and 2618. I knew that going in. I also knew that I'd rather trust the folks at Rallispec to steer me right based on how I'm using the car. Not saying that 2618 is a bad idea for a daily driver, but when I posed that question to Rallispec they advised against it based on longevity of the motor if its being used as a non full race set up, (which is 99.99% percent of us, me included). True, 4032 doesn't have the same properties as 2618 but if I'm staying 350WHP or less, (and I am) and the car is only tuned and wrenched on at Cobb, arguably one of the best tuners in the country, (which it is) and the fact that its only run on the track with a can of 32oz. Torco that is also on a Torco specific map, (which it is). I'm fully confident that this motor is gonna be just fine

 

Agreed that running pushing stock internals is a bad idea at 400HP. I wouldn't ever do it and like I said, its been done but I wouldn't be comfy with the risk.

[Tehnation]

no dyno, no mod list ....its hard to say anything when no one knows what your working with! If you haven't done so in another thread then you should list your mods!!! That would make this discussion a lot more interesting. But all I know is that you have a vf52 running e85 and you bent a rod. If your engine builders tuned it there should be a dyno, and if not that means they didn't tune it or used some bullshit. If you hammered down the pedal on an untuned, bullshit tuned, base tuned, or ots tuned car then that's probably why u bent a rod. I have yet to see any real dyno info.... why bring a car to a shop to get tuned without a dyno, might as well get an etune from a reputable person than some random shop.....

 

I want more info!

[xtea]

I was road tuned.

 

Mods: intake, tmic, 3 port bc, bpv, up, dp, elh, dw850, dw65c, group n mounts, jmp billet vf52.

 

Let's assume the tune was knock free. Let's assume this guy does conservative tunes. Could the tune bend rods or spin bearings? Bending rods is low end torque which I honestly have been in pursuit of. Spun bearings is oiling issues which despite positive blackstones doesn't discount cumulative damage that may have occurred with previous owners.

Edited May 9, 2016 by xtea

[fahr_side]

If you run the VF-52 for a while just ask your tuner to ramp the boost up a little slower, not spool it so hard. It's high cylinder pressure at low revs that bends rods.

 

The rods are bent by very high torque at very low revs (as per OP), in compression.

 

You usually bend a rod from too much cylinder pressure at low revs, where overrevving leads to broken rods. A bent rod will usually result in one cylinder not firing at all, massive vibration, but not always strange noises.

Yes, that's safer in terms of avoiding bent rods.

I think I've made this pretty clear by now. IF you've bent a rod, "just ask your tuner to ramp the boost up a little slower, not spool it so hard". I thought you'd have a VF-52 surging hard during spool before you bent a rod but who knows until it happens?

Edited May 9, 2016 by fahr_side

[Tehnation]

If the headgasket blew or a loose/bad head bolt went and let coolant into the cylinder then that coolant would prevent the piston from completing its rotation, forcing that energy somewhere.... ie the rods.

 

A lot of things could have went wrong

 

Its hard to say anything until you actually open it up and tell us.

 

But your setup looks like a 300+whp setup on pump gas let alone e85, not sure what jmp turbo can do!

Edited May 9, 2016 by Tehnation

[Tehnation]

I think I've made this pretty clear by now. IF you've bent a rod, "just ask your tuner to ramp the boost up a little slower, not spool it so hard". I thought you'd have a VF-52 surging hard during spool before you bent a rod but who knows until it happens?

 

why would you want to go back to that person, after they built,not sure who installed your mods, and tuned a motor that lasted 15 minutes? Why is the customer having to tell the builder/tuner how to not break his engine lol.

 

Unless you bent his arm to tune it that way, i would imagine this tuner has little experience tuning subarus or maybe tuning e85.

Edited May 9, 2016 by Tehnation

[Tehnation]

poor tuner.... as in i feel sorry for him.. you probably shouldn't have tuned it on e85 on a used motor without pulling it apart to inspect it thoroughly. So ultimately it is ur fault, but that tuner should have set u straight!

 

I completely overlooked that it was an engine 2+ owners 100k+ miles..... lol , anything could have went wrong with that kind of scenario lol....

Edited May 9, 2016 by Tehnation

[xtea]

I think I've made this pretty clear by now. IF you've bent a rod, "just ask your tuner to ramp the boost up a little slower, not spool it so hard". I thought you'd have a VF-52 surging hard during spool before you bent a rod but who knows until it happens?

 

Oh I hear yeah, mostly was posting that information for the other guy. I've gone with your advice and am doing the drop ins and arp studs and the rest oem except for my bolt ons. Only thing is my builder won't be able to retorque the studs at 1000 miles per arp's instructions.

[xtea]

If the headgasket blew or a loose/bad head bolt went and let coolant into the cylinder then that coolant would prevent the piston from completing its rotation, forcing that energy somewhere.... ie the rods.

 

A lot of things could have went wrong

 

Its hard to say anything until you actually open it up and tell us.

 

But your setup looks like a 300+whp setup on pump gas let alone e85, not sure what jmp turbo can do!

 

why would you want to go back to that person, after they built,not sure who installed your mods, and tuned a motor that lasted 15 minutes? Why is the customer having to tell the builder/tuner how to not break his engine lol.

 

Unless you bent his arm to tune it that way, i would imagine this tuner has little experience tuning subarus or maybe tuning e85.

 

poor tuner.... as in i feel sorry for him.. you probably shouldn't have tuned it on e85 on a used motor without pulling it apart to inspect it thoroughly. So ultimately it is ur fault, but that tuner should have set u straight!

 

I completely overlooked that it was an engine 2+ owners 100k+ miles..... lol , anything could have went wrong with that kind of scenario lol....

 

I don't know why you were hot to blame the tuner before. He advised me against 21 psi but I see lots of vf52 dyno plots with 21psi so I thought what the heck. Yeah it was an older car and I should not have pushed it so that's why I am here.

 

I won't be paying the shop extra labor to tear apart the engine beyond pulling off the things that can my transferred to the new block. If they see something when they drop the oil pan I'll update.

 

As it is I think the low end torque either bent the rod, heads lifted which led to a bent rod, or the bearing gave out from abuse. Either way I think I am good going with just the drop ins and arp studs with the next block.

[Tehnation]

If the motor were in front of him and he knew the same information and he still went ahead and did it, then yea blame the tuner and the customer, its the blind leading the blind. Plenty of experienced tuners would tell you to go elsewhere, to **** off or not do it to avoid the headache. No leakdown/compression test? No borescope? Just you saying its a 100k+ used pig, lets go for broke...

 

Its not really his fault, but he should of told you to go home.

[dahoseman]

I ran my 08 STI pro-tuned @21 PSI on the stock longblock with a Dom1.5XTR turbo + ID 1000cc injectors + exhaust. After many thousands of miles, I sold it with >90,000 miles before doing the 90,000 mile service. I never tracked it or ran it incredibly hard, but I ran it to redline and drove it "like a teenager" frequently without any engine problems

[fahr_side]

As it is I think the low end torque either bent the rod, heads lifted which led to a bent rod, or the bearing gave out from abuse. Either way I think I am good going with just the drop ins and arp studs with the next block.

A head lifting isn't going to lead to the rod bending. Water doesn't seep into the cylinder while the engine is stopped and while running not enough gets in to hydrolock the cylinder. But yes, the Manley drop-ins plus studs is how I would approach this.

Only thing is my builder won't be able to retorque the studs at 1000 miles per arp's instructions.

Don't worry. Almost no-one pulls the engine a second time to torque those studs again.

 

I ran my 08 STI pro-tuned @21 PSI on the stock longblock...

...and the '08~ STi motor has a lower static compression ratio than regular LGT/WRX/FXT stuff and lower dynamic compression due to the D-AVCS layout.