Petrol Alternative Engines...

for questions and answers about alternative power transplants on the T25, GTi, Porsche,Subaru etc, this is the place. You must register to post but anyone can read.

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Subaru Options

Post by HarryMann »

Subaru Engine Types and Options

The normally aspirated (NA) flat 4's weigh about the same as a WBX and after installation there's always a cleaner and more spacious engine compartment (wiring and hose-wise by a big margin). They are smooth, have a wide rev-range (reducing gearing problems), abundant torque from 1500~4500 and are reliable.
These engines were designed as a tightly integrated power pack (the ancillaries, intakes, ignition etc are not just bolted on as an afterthought!).
The ignition and injection systems were state of the art pretty well at the date of your engine, and all Subarus are noteworthy for a continual development and change cycle, that creates incompatibilities across engine series change dates and even within a given series (mainly harness/ECU/AFM). One difference to most other engines - Subaru water pumps are at the bottom of the engine and pump upwards (theoretically better). The whole range has a common engine/gearbox interface (AFAIK), something that may have helped to popularise them as upgrades.
Modified appropriately, they are also used succesfully in US lightweight private aircraft (equiv. to PFA in the UK), as are VW Aircooled flat fours.

All 2.2 NAs are SOHC engines; early 2.5s were DOHC and the late ones (1999 year change) were SOHC (considered better). The 3.3 6 was DOHC, and has Variable Volume Inlet tuning as well.

Despite their recent rise to stardom, it is rare for turbocharged Subaru engines to be fitted to roadgoing T25s; even in the States there are only a handful. They are predominantly of 2.0L capacity and most have 'pull' type cluches. It's a tight fit but 6 into T25 will go making the 3.3 SVX easily preferred over turboed lumps, especially for the really heavy Campers. Maybe 30-40 have been converted, none in the UK AFAIK.

All flat 4/6 cyl. Subaru engines have maybe one achilles heal - they don't take kindly to overheating and even small air pockets in the water jackets, especially the 2.5 DOHC. This just means a good cooling system layout that can be bled easily and reliably is required (T25 rads cope fine). They can run lowish oil pressures, occasionally low enough to worry some people, but its not too common. The electrics, if installed sensibly, rarely give problems, and the ECU has an inbuilt fail-safe 'limp home mode', if it detects sensor or general system failures. Injected WBX fuel pumps can be used.

Mechanically, they can certainly be worth looking at (compression and oil pressure wise) at up to 125,000 miles - some say more of course. They will run well to 200,000 in Legacies. Unless you know exactly what you're doing, never buy just the engine without the harness that came out of the same car. The full harness from behind the dash, ECU, relays etc. need to come out, together with the engine sub-harness which involves removing the n/s wing of a Legacy. Garner the Air Flow Meter (AFM) and all intake plenums and ducts as well. The AFM and ECU are matched pretty closely, so no guarantees when swapping around, though small variations in part nos usually work. Many suitable Legacy donors are automatics and can be used for comversions with a few provisos.

They are not cheap to install, requiring a special adapter plate and flywheel (VW clucth) or a custom made bellhousing (which allows the Subie flywheel, clutch and starter to be used) Additonally, engine mount, exhaust, optional sump shortening (mandatory for syncros), coolant pipes and a job on the harness that can be done at home (but might be £250 or more if you ask a savvy auto-electrican).
A thorough job would involve cam follower bearing replacement, belts, and some crank seals, rather than dropping straight in, dependent on its history. If any cylinder is far off the others in compression (125~175 typ) then they are probably not economical to repair.

The 2.2 EJ22 (Legacy) is the most common variant used, as it offers far better pulling power than even the 2.1 DJ WBX, yet combined with good economy, long term durability and reliability commensurate with its ten-year later genesis - yet can be bought extremely cheaply (expect to pay maybe £150 - 500). Some say with heavier vans, the 2.5 (esp the SOHC) returns almost as many mpg.

The engines

90-94 2.2L (EJ22)- cheapest and the usual T25/T3 bus conversion choice
Ideal capacity and power (125-130BHP) for a good match with the van, they make a big improvement in driveability, especially for hilll-climbing and motorways.
N.B. '90 vintage engines may have different pistons to '91 on, and it's been suggested they might develop high oil consumption prematurely.

95-99 2.2L - more highly evolved, more expensive, with slightly more power (130-140BHP)

95-99 2.5L DOHC, a top-end rebuild is suggested by US users, imports might have VVT (Variable Valve Timing)

99- 2.5L SOHC - preferred 2.5L, excellent for syncros and heavy campers.

2.0L and 2.2L Turbo 4 & WRX (2.2L Turbo rare in the UK)
Complex to install, but go like stink and burn fuel like water. Not really recommended!

04- 3.0L 6 (H-6) Only one of these Subaru gems has been installed in a US vanagon. Ultra-compact H6, chain driven cams, 21st century design.

92-95, 3.3L DOHC flat 6 beautifully engineered 230HP torquey beasts, tolerable economy. A tight fit. Gold dust in the UK!
96-97 - later electronic/emission spec.


Several hundred conversions have been done (maybe 4~500 in total), so there is a wealth of knowledge up out there. Two good US forums are:-

Warren Chapman's suburuvanagon group
Scott Daniel Foss' turbovans group (deals with TDi and Subaru, not turbo specific despite the forum name)

Conversion parts:

United States:-
KEP (Kennedy Engineered Products) Parts, Adapter plates, flywheels, uprated VW clutches, wiring diagrams, instructions etc (KEP effectively started the US subievan ball rolling 6 or so years ago, they are predominantly a sandrail racing shop/supplier (custom flywheels etc);
SmallCar - complete conversions, harnesses and nearly all parts); Others - shortened sumps, wiring harness help etc.
Lot of good info here, despite being a rare WRX conversion (into a Syncro):
Shortened sumps, engine mounts etc.
Aussie VW Forum (all subjects):

RJES Ltd - Custom Subaru/VW bellhousing, eng. mount, coolant manifolds/pipes, cast sump, throttle cables, conversion CD/DVD:

TSR drag racers - complete in-house conversions , JDM Subaru engines and adaption parts:

Lot of good info here, despite being a rare WRX conversion (into a Syncro):

Shortened or alloy sumps:
Germany (Martin) designed for cantilevered Beetle style engine mounting

Racing Subaru style 1
Racing Subaru style 2

Wrt pros and cons of custom sumps, see this thread: Alt sump discussion?

For LPG'ing Subaru engines, Steve Shaw at Gasure would be a first call:

Last edited by HarryMann on 13 Apr 2008, 22:47, edited 20 times in total.

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Post by Simon Baxter »

95-99 2.5L DOHC, a top-end rebuild is suggested by US users, imports might have VVT.

Can you clarify this please Clive.

Variable vein turbo or Variable valve timing?

'86 VW T3 syncro panel
'89 VW T3 Westy Atlantic
'90 VW T3 BW Double Cab
SJ Baxter LTD/Brickwerks

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Post by HarryMann »

Variable vane turbo or Variable valve timing?

Variable Valve Timing!

Richard Jone's (RJES Ltd) ccnversion kit demonstration Syncro has one of these imports fitted, and yippee, he let me drive it last weekend at Coney Farm.

Rev limited to 4,500 it was no slouch and smooth as silk.

I believe it came out of a Forrester, and the import model I think he said was something like a 'Sovereign, but memory's a bit bad on that, it could equally have been a 'Victory' model, or even a 'Windsor' or 'Buckingham' :-)

DOHC, 2.5

There was a Subaru Maint Bulletin in the States a year or two ago on 2.5s w.r.t. a coolant additive to plug gasket leaks. I'm sure they're not all bad at all, but after a few years, 100,000 miles or so, maybe head and gasket problems start to crop up - Subaru are a bit like VW with warranty claims - buyer beware, which created a bit of a fuss.

Richard had to rebuild his camgear anyway, due to it coming from a crashed car, but not sure if he had the heads off or not. He certainly hasn't any problems with that side of it at the moment!

Last edited by HarryMann on 10 Mar 2006, 22:22, edited 1 time in total.

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Post by steve8090 »

Don't know who deleted my last thread, I don't really care, however when a statement is wrong and passes the wrong information over to prospective members and clients, thats when I care, paragraph three of your statement Mr.Hell is incorrect, you do not need to run a carburettor for LPG on injected vehicles, the stock injection is fine as it is and will run a dual fuel vehicle quite adequately and with the introduction of a lambda probe you can even run a decent closed loop system such as the Millenium (Leonardo) system.
Steve Shaw
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Full Service, LPG conversions, Security and Camper Accessories.
see for full details.
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Post by HarryMann »

Thanks Steve, we have no idea what happened to that post, but the update has been copied across to the original article...

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Re: Petrol Alternative Engines... Read before asking questions

Post by Titus A Duxass »

Holy thread resurrection Batman!
VW T3 GTi Camper 2,0l

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Re: Petrol Alternative Engines... Read before asking questions

Post by HarryMann »

never buy just the engine without the harness that came out of the same car.

.. good point, but not only that.

Always try to find and record the Reg No and VION number of the vehicle that engine and harness came from, you may have enormous problems gettinsg correct spares and identifying mod standards without those... Subarau for instance would want the Reg No in preference I believe.

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Re: Petrol Alternative Engines...

Post by boardmonkey »

Hi Harry,

The CLICK link is busted...

Cheers, Richard
''Nellie'' born 01/87 Hannover WV2ZZZ25ZHH067456 now fitting with a new heart EJ25 N/A

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Re: Petrol Alternative Engines...

Post by clift_d »

It's always worth trying the Internet Archive (Wayback Machine)

1988 LHD T25 1.6TD Westfalia Club Joker Hightop syncro

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Re: Petrol Alternative Engines...

Post by Boardman »

Hi all
I have an 87 caravelle with a 1.6 ez petrol conversion ,anyone else out there ?
Any issue you may have had or having .


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