Sti - 2.5RS

stickygreen · 04-14-2003, 11:43 PM

What are the difference between the 2.5RS engine and the Sti engine, besides the fact that the Sti has a turbo? Are the engine blocks basically the same and what about the heads??

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Crawdads · 04-15-2003, 12:37 AM

wow, cast iron pistons! And bored out too make 2.5l from 2.5l?

sorry man, i dont want to be a total ass, but that paragraph made no sense and was full of misinformation.

Having not read all the specific posts concerning the new motor, IIRC the new block will be semi closed deck design, the heads include have sodium filled valves for better heat transfer and variable valve timing.

ANZAC_1915 · 04-15-2003, 12:40 AM

Oooh, more SCC disinformation.

I don't believe any of the major components are common with the 2.5 RS or Legacy (naturally aspirated) motors.

The STi 2.5 has unique: block, rods, crank, pistons, cams.

The heads are the AVCS 16v DOHC heads. The RS/Legacy etc use 16 v SOHC heads. Big difference.

Glenn

CloNeGTS · 04-15-2003, 01:19 AM

Where are you finding documentation on the STi engine? Anywhere public?

Jewbaru · 04-15-2003, 12:48 PM

Quote:

Originally posted by CloNeGTS
Where are you finding documentation on the STi engine? Anywhere public?

It was printed in SCC that the motor was a tweaked EJ25 from the RS, which like Glenn said, is wrong.

AFAIK, it's pretty much the EJ20 STi block, only worked to make more displacement (prolly different stroke/bore).

ANZAC_1915 · 04-19-2003, 01:23 AM

Quote:

Where are you finding documentation on the STi engine? Anywhere public?

Quote:

AFAIK, it's pretty much the EJ20 STi block, only worked to make more displacement (prolly different stroke/bore).

It is similar to the block but there are some new and important differences.

It does sound like there is a lot in common with the 2.5 XT Forester and Baja turbo and the STi engine.

I suspect the revised block etc. was used in all of them.

I was reading a SCC on the newstand today and found even more errors (picture of 04 WRX interior labelled as STi, and they also said the DCCD uses a "clutch pack", which it doesn't).

So, my advice is to pretty much ignore anything you see in SCC.... or at the least the finer details.

For anyone who wants to know more about the mechanical part of the DCCD, I direct you to the Legacy H6/WRX Auto VTD documentation.

Glenn

Kostamojen · 04-19-2003, 03:14 AM

I think this engines closest relative is the AVCS EJ25 in Japan, although the semi-closed block and special valve are aparently different I think the head design is simular. In my eyes, this engine is more of an emalgamation of various current EJ engines, most of which we dont have here in the states

ANZAC_1915 · 04-19-2003, 11:13 AM

No, the block, crank, rods, pistons are all new modifications of current components.

Apart from heads etc, it is not a parts bin special.

Even the cams used in the heads are different (the metalurgy, don't know about the profile though).

I am not even sure it has an EJ designation.

Glenn

Kostamojen · 04-20-2003, 12:45 AM

Well I dont mean "from the parts bin" I mean previous design ideas. The closed deck design and forged parts are obviously 22B related experiments, combined with new technology like the valves and drive by wire, combined with recent JDM AVCS and DOHC tech. The ideas were all there, just not all put into the EJ25 before.

ANZAC_1915 · 04-20-2003, 01:01 AM

This is not an EJ25...

Kostamojen · 04-20-2003, 02:15 AM

As far as ive heard, its still the same dimensions as an EJ25 but with the semi-closed block and different material construction... Still the same dimensions and everything, so why not an EJ25?

shirokuma · 04-20-2003, 02:56 AM

I think we are running up against a dictionary definition of "all new" vs. "evolutionary".

The 2.5 turbo is an evolution of previous Subaru motors. In some ways it is definitely brand new - there was no 2.5-litre turbo factory motor before. In some ways it's merely evolutionary - much of the design isn't going to differ greatly from previous designs used in their flat fours.

Technically, the current JDM 2.0-turbo isn't terribly different from the original, hand-made motors in the Ver. 0 STi's. However, it's obvious nearly everything has evolved and been tweaked since then.

Base line - the 2.5 turbo motor is not a "tweaked" 2.5 NA motor. It certainly is related to it, but then, Whoopi Goldberg and Halle Berry's physical makeup also may technically be 90% the same, but it's the other 10% that makes a world of difference.

Cheers,

Paul Hansen
www.apexjapan.com

ANZAC_1915 · 04-20-2003, 11:00 AM

I'll take Halle Berry.

gills · 04-20-2003, 07:55 PM

Ha! are you kidding?!? Whoopi Goldberg is a friggin' alien!!!

04-14-2003, 11:43 PM	#1
stickygreen Scooby Newbie Member#: 22175 Join Date: Jul 2002	Sti - 2.5RS What are the difference between the 2.5RS engine and the Sti engine, besides the fact that the Sti has a turbo? Are the engine blocks basically the same and what about the heads?? * Registered users of the site do not see these ads.

04-15-2003, 12:37 AM	#2
Crawdads Scooby Specialist Member#: 30907 Join Date: Dec 2002 Chapter/Region: SWIC Location: Cat Keyboard Cat Vehicle: SWP GDB-G	wow, cast iron pistons! And bored out too make 2.5l from 2.5l? sorry man, i dont want to be a total ass, but that paragraph made no sense and was full of misinformation. Having not read all the specific posts concerning the new motor, IIRC the new block will be semi closed deck design, the heads include have sodium filled valves for better heat transfer and variable valve timing. Last edited by Crawdads; 04-15-2003 at 12:44 AM.

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04-15-2003, 12:40 AM	#3
ANZAC_1915 Moderator Member#: 456 Join Date: Oct 1999 Chapter/Region: NWIC Location: Redmond, WA, USA Vehicle: 2008 Forester XT Steel Gray Metallic	Oooh, more SCC disinformation. I don't believe any of the major components are common with the 2.5 RS or Legacy (naturally aspirated) motors. The STi 2.5 has unique: block, rods, crank, pistons, cams. The heads are the AVCS 16v DOHC heads. The RS/Legacy etc use 16 v SOHC heads. Big difference. Glenn

04-15-2003, 01:19 AM	#4
CloNeGTS Scooby Newbie Member#: 23341 Join Date: Aug 2002 Location: Overland Park, KS Vehicle: 04 Rex STi WRB/Gold	Where are you finding documentation on the STi engine? Anywhere public?

04-19-2003, 03:14 AM	#7
Kostamojen Scooby Guru Member#: 2272 Join Date: Sep 2000 Chapter/Region: BAIC Location: haha XD Vehicle: 95 L AWD LIFTED!!! 1970 Subaru FF-1 Coupe	I think this engines closest relative is the AVCS EJ25 in Japan, although the semi-closed block and special valve are aparently different I think the head design is simular. In my eyes, this engine is more of an emalgamation of various current EJ engines, most of which we dont have here in the states

04-19-2003, 11:13 AM	#8
ANZAC_1915 Moderator Member#: 456 Join Date: Oct 1999 Chapter/Region: NWIC Location: Redmond, WA, USA Vehicle: 2008 Forester XT Steel Gray Metallic	No, the block, crank, rods, pistons are all new modifications of current components. Apart from heads etc, it is not a parts bin special. Even the cams used in the heads are different (the metalurgy, don't know about the profile though). I am not even sure it has an EJ designation. Glenn

04-20-2003, 12:45 AM	#9
Kostamojen Scooby Guru Member#: 2272 Join Date: Sep 2000 Chapter/Region: BAIC Location: haha XD Vehicle: 95 L AWD LIFTED!!! 1970 Subaru FF-1 Coupe	Well I dont mean "from the parts bin" I mean previous design ideas. The closed deck design and forged parts are obviously 22B related experiments, combined with new technology like the valves and drive by wire, combined with recent JDM AVCS and DOHC tech. The ideas were all there, just not all put into the EJ25 before.

04-20-2003, 01:01 AM	#10
ANZAC_1915 Moderator Member#: 456 Join Date: Oct 1999 Chapter/Region: NWIC Location: Redmond, WA, USA Vehicle: 2008 Forester XT Steel Gray Metallic	This is not an EJ25...

04-20-2003, 02:15 AM	#11
Kostamojen Scooby Guru Member#: 2272 Join Date: Sep 2000 Chapter/Region: BAIC Location: haha XD Vehicle: 95 L AWD LIFTED!!! 1970 Subaru FF-1 Coupe	As far as ive heard, its still the same dimensions as an EJ25 but with the semi-closed block and different material construction... Still the same dimensions and everything, so why not an EJ25?

04-20-2003, 02:56 AM	#12
shirokuma Scooby Specialist Member#: 5489 Join Date: Apr 2001 Chapter/Region: NWIC Location: The Empire of Seattle Vehicle: 2013 FR-S AVO Orange	I think we are running up against a dictionary definition of "all new" vs. "evolutionary". The 2.5 turbo is an evolution of previous Subaru motors. In some ways it is definitely brand new - there was no 2.5-litre turbo factory motor before. In some ways it's merely evolutionary - much of the design isn't going to differ greatly from previous designs used in their flat fours. Technically, the current JDM 2.0-turbo isn't terribly different from the original, hand-made motors in the Ver. 0 STi's. However, it's obvious nearly everything has evolved and been tweaked since then. Base line - the 2.5 turbo motor is not a "tweaked" 2.5 NA motor. It certainly is related to it, but then, Whoopi Goldberg and Halle Berry's physical makeup also may technically be 90% the same, but it's the other 10% that makes a world of difference. Cheers, Paul Hansen www.apexjapan.com

04-20-2003, 11:00 AM	#13
ANZAC_1915 Moderator Member#: 456 Join Date: Oct 1999 Chapter/Region: NWIC Location: Redmond, WA, USA Vehicle: 2008 Forester XT Steel Gray Metallic	I'll take Halle Berry.

04-20-2003, 07:55 PM	#14
gills Scooby Specialist Member#: 11316 Join Date: Oct 2001 Chapter/Region: Tri-State Location: Long Island, NY Vehicle: 2004 STi E30 325is	Ha! are you kidding?!? Whoopi Goldberg is a friggin' alien!!!