How much milage out of a built IAG block?

[Mortal2None]

I bought Save the Wagons Blue s402 wagon right before the pandemic hit. About 2k miles later, I was accelerating onto an on ramp when it felt like I hit the rev limiter at 6700 RPM and it sounded like the engine backfired out of the intake. (the engine deaccelerated so hard my arm hit the wheel with such force I thought I broke it)

 

At idle, the VTA Crawford Race AOS smokes like a witches pot on Halloween and if I pull the dipstick, it will splatter small amounts of oil out at idle like a cut carotid artery. At first I thought it skipped a tooth on the cam gear or something of that nature but after seeing the other two things I'm guessing good old ringlands?

 

I haven't had the time to do a compression, leakdown or borescope check yet but judging by the blowby from the AOS, I think the writing is on the wall. It was a IAG stg1 block and was doing 324HP (@5546) and 349TQ (@4458) (tuned by Perry/The Subaru Shop) and should have been well within the power limits. (AFR was high 10's low 11's at WOT so no lean conditions, A bit too rich but I guess safe) Engine was install by AWJ in NH so all the work was done by reputable shops I believe.

 

I was hoping to get at least 50K out of the engine as 5k is a huge disappointment. Is everyone investing in RA blocks now or is there something better as I'm very hesitant to go the IAG route again. I would love to do a high revving destroker but I don't hear much about those and I personally hate the piston slap sound on cold days of the forged pucks. (hence thinking RA) Can anyone recommend someone in the tri state area that knows how to properly build a Subaru engine with some longevity in mind?

[Pleides]

IAG blocks are what my shop Surgeline uses for built motors. I'd assume a potential fault somewhere in tuning or parts install that caused some issues, but shit happens.

 

Most use type RA blocks these days. A built block will always last a much shorter length of time than a stock block up until the higher power levels you can really eek out of these without insane turbo lag because of the wear forged pistons/rings cause that creates greater cylinder clearance. When Subaru made the S209 STI a couple years ago, they tried to engineer a forged set of pistons in their factory EJ and gave up on the idea because the piston rings would fail at around 100K miles of simulated wear.

 

I'd stick with a Subaru OEM shortblock unless you're pushing a serious amount of power. The 400+ WHP levels will be better for those blocks because they can take more of a beating from detonation.

[Mortal2None]

Thanks Pleides!

 

The RA block is using the same crank as the normal STi's still so my guess is mid 7k RPM is the limit until the drilling on the crank deprives the rod journals of oil? I am probably going to go the RA route with re-gapped and coated rings as I like to drive the car year around.

 

This may sound silly but with head flow work and just replacing the crank and rods with billet aftermarket on the new RA block does anyone know if the stock RA pistons can handle 8k RPM engine speeds?

 

I have been searching for more info on the RA blocks and all I find is how with 450-500WHP they seem to be holding together so far. (quite impressive)

[shralp]

Wow, surprised an IAG stg.1 would fail at such a low power level in relation to what it should be able to handle. That said, if you aren’t totally clear on the history of the car from day 1, I’d suspect there’s other factors that contributed to the failure. As Mentioned above, IAG is definitely a top builder for Suby engines. They definitely know what they’re doing.

 

Another option would be to talk with Rallispec as they are in your neck of the woods. Before IAG really came on the scene hard in the last few years, Rallispec was another good option for built motors. I opted to have Dave build me a slightly modified version of their Street Value short block for my track car. Since it was a partial daily driver at the time as well I was concerned about long term durability, piston slap, etc. He suggested Cosworth 4032 Forged for me. While they are still forged, the 4032 doesn’t have quite the expansion and contraction of typical 2618 forged pistons so you can run close to OEM ring clearances, I.e.- no piston slap. Still running fine in my track car today pushing about 340whp, and yes the car gets driven hard on track

 

Dave would also be a good source to chat on capabilities if the RA block as well as de-stroking options

Edited February 16, 2022 by shralp

[Pleides]

Thanks Pleides!

 

The RA block is using the same crank as the normal STi's still so my guess is mid 7k RPM is the limit until the drilling on the crank deprives the rod journals of oil? I am probably going to go the RA route with re-gapped and coated rings as I like to drive the car year around.

 

This may sound silly but with head flow work and just replacing the crank and rods with billet aftermarket on the new RA block does anyone know if the stock RA pistons can handle 8k RPM engine speeds?

 

I have been searching for more info on the RA blocks and all I find is how with 450-500WHP they seem to be holding together so far. (quite impressive)

 

I would think the RA pistons wouldn’t enjoy the power required of an EJ to actually make any sort of power at 8K RPM. What kind of turbo would that require having? A Dom 1.5XTR? I wouldn’t run that on a cast block. Obviously consult with your tuner first, but I’d do forged everything if you want to spin the crank that fast. That’ll be an expensive bill, getting everything built to that level with a huge turbo. Are you already on a FMIC with equal length headers, a big intake, ID1050X/1300X etc?

[Mortal2None]

Thanks Shralp and Pleides!

 

As far as what the car had done to it, here is the original FS thread:

 

https://legacygt.com/forums/showthread.php/ma-taunton-legacy-2005-gt-wagon-sold-276499.html

 

I guess Boxkita called it on the "it broke" part but she will live again. xD

 

@Shralp, you are still on the same cozzie pistons and they are holding up? I will give Dave a call as well and I forgot about Rallispec.

 

@Pleides Its currently a GS TMIC with a madrig custom scoop but i have been thinking about retrofitting a 08-14 WRX COBB or Perrin FMIC. It still has the HTA71 that it came with but I am thinking about a rotated setup this time but that is probably outside the realm of a stock RA setup with any kind of longevity in mind.

[NORULZleggy]

I tell everyone that no matter what the prev owner says about their car never believe it. Cause it can be running great for them and then for you it takes a crap. But this is the fun of buying modified car. IT WILL BREAK AT SOME POINT. Early or late in the process.

[shralp]

Thanks Shralp and Pleides!

 

As far as what the car had done to it, here is the original FS thread:

 

https://legacygt.com/forums/showthread.php/ma-taunton-legacy-2005-gt-wagon-sold-276499.html

 

I guess Boxkita called it on the "it broke" part but she will live again. xD

 

@Shralp, you are still on the same cozzie pistons and they are holding up? I will give Dave a call as well and I forgot about Rallispec.

 

@Pleides Its currently a GS TMIC with a madrig custom scoop but i have been thinking about retrofitting a 08-14 WRX COBB or Perrin FMIC. It still has the HTA71 that it came with but I am thinking about a rotated setup this time but that is probably outside the realm of a stock RA setup with any kind of longevity in mind.

 

Yup still on the Cosworth 4032

[Tehnation]

Whats an RA block? Are they better?

[whitexc]

Whats an RA block? Are they better?

Was thinking the same thing. How much more ching, better durability, capability? Too late for both of us!

 

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[Berge56]

The RA blocks are built a little stronger and cost slightly more than the regular EJ257. Some of the key features of the RA block is as follows.

Same casting as the latest EJ motors, "705"

Piston crowns are 2mm thicker

More support on piston wrist pins

Lower amount of cantilever produced

Slightly heavier pistons increase durability

Same strong Con Rods as 2018 STI

Overall, less prone to failure than previous STI blocks

 

Here is the part number for the RA block: 10103AD020

[whitexc]

Hmm. Cool.

 

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[k00laid83]

I'm running a RA block and I'm loving it. I'm currently just finishing up the break in process and have been tuning. So far she pulls nice and she's ready to get fully tuned!