Engine build for 300-350 flywheel hp

[Dubber91]

Engine Build advice- 300-350 fwhp

Chaps,

New to this forum and thought I'd start by initiating a discussion on the build of a decent-spec subaru motor for use in an alternative vehicle; in this case a classic VW beetle.

So I'm searching for base engines, and plan on rebuilding from the crank up to a completely finished motor. The question is, what engine should I start with in order to achieve the ultimate goal of 300-350 flywheel Hp?

I understand that the 93- STI motors are the units with fully forged bottom ends, and closed deck block, meaning they are more suitable for high power applications. But is this necessary? I've always been a bigger fan of displacement; would going EJ25 turbo be a better route? In which case, which engine should I look for?

I'd like to avoid sleeving blocks and expensive engineering exercises; but am happy to port, modify and lighten where necessary. Are the stock forged pistons good enough? Should I be looking at later base engines?

Finally, what spec would you look for externally? turbo, injectors etc? I already have an ECU lined up and am happy to tune myself- I've a fair amount of experience on this.

Cheers for the advice in advance.

Steve

[Miggs]

If it were me I would go for any closed deck sti engine, arp head bolt to stud conversion, forged pistons (although not esential) an equal length manifold, (it will loose the scooby rumble but give more power gains) and a minimum of a td05 turbo which is good for 350bhp,pink injectors, (I know these are sti equipment just not sure what year) and avoid a version 3 or 97 ecu as these need a piggy back unit to map them, and I personally would stay EJ20 engine, if you find a forum called volkszone (vzi) there are plenty of people putting the impreza engines in beetles on there so lots of hints and tips, most go for the N/A unit but the principal is the same for fitting

[Dubber91]

Thanks miggs; yup aware of VZI, I've done a few engine conversions in the past so not too worried about that. Have my own ECU it was the base engine that I was worried about.

Do the STIs come with forged pistons? I was looking at a 94 v2 eJ20....

I'm assuming td05

Isn't standard on any engines?

[Miggs]

As far as I know some sti import engines came with forged pistons but not sure if that was standard or if it's been modded before it was shipped over here

The TD05 I have been informed in the past is on the import sti's and the bug eye wrx as standard, with the turbo being where it is in the car it's possible to see if there's no heatshields on it

If you use a wrx engine and a TD05 turbo 16g you will see a reliable 300bhp an 18 or 20g will be leggy and you would need to uprate the injectors, if you settle for the wrx engine, TD05 turbo fuel pump and panel filter and a map it's the cheapest option, the wrx engines are around 220 standard, the sti is 280, the wrx will be cheaper but need more upgrades the sti the opposite, I hope that's not too confusing lol, its harder for me to keep on track on my phone, if you need any more info I can jump on the laptop later and do a list of what you can use if you like

[Dubber91]

Thanks miggs! Yes that'd be really helpful; from what I gather taking an sti motor to 350hp is a more simple job than taking a wrx motor to the same level; although by the sounds of it a hybrid of both sti bottom end and wrx ancillaries (turbo etc) seems to be the way to go.

If there is a proven spec-list of an engine that makes that power reliably, I'd appreciate it. It at least gives me something to work too even if it means cutting a few corners and saving a few pennies here and there.....

[Miggs]

If I was doing this for reliability I would go for a bigger turbo capable of 400bhp, then as your down 50bhp on what you want it's not at its limit straining to push at top end, I know a guy that took a standard internals wrx engine to just over 500bhp with no issues, the trouble is the bigger the turbo the more lag your gonna get

Have you considered a rotrex charger?

[Dubber91]

I have worked with rotten chargers and to be honest I'm not a massive fan given the cost; I think I'd rather go turbo as I'm guessing I'd be looking at a c30 or bigger.....

It may be a nicer thing to mount in the little engine bay though......

[Scooby Pete]

good luck with the build :)

[Miggs]

Not hand chance to look into it for you yet as been on the wife's golf all day and just decided to call it quits on the labour side and use vag com instead, I forget I can do that lol, I'll get on it for you in the morning asap

The reason I suggested a s/c is ease of fitting, cheap maintenance and boost from the offset and with the rotrex they can easy see 300-350 with little mods needed, plus with a charge cooler fitted instead of an intercooler, the charge cooler could be left inside the car as in a beetle space in the back is at a premium and a front mount would spoil the classic look, obviously you can use a charge cooler for a turbo but I'm thinking of the build my mate did on his mk3 vr, he had a vortech on it but that topped out at 300 and was a large unit, the rotrex was as big as an alternator (half the vortech) and was easily seeing 350 and made a lovely noise too, I was thinking, scooby rumble, rotrex whine and sacking noises like a hoover cool

[Gambit]

Yep best of luck with the build. I would also go for the STI engine :) 

[Dubber91]

Ok so an sti bottom end will handle that no probs? What's the difference between Earle and late bottom end bearings? Was there an improvement on the later engines?

What about heads? Sti the way to go? For the sake of £400 I'm sure I could stretch to some forged pistons but would it be worth arp bolts or head work?

Seve

[Miggs]

I'm not sure on the specific differences between early and late but will find out, the one I mentioned that went over 500 on standard internals was a blob eye and a wrx but everybody seems sure the sti is the only one that should be able to do that, I was there when said car was on the dyno and everybody was amazed, there were loads of people saying it wouldn't be driving home, the owner is a very well known subaru tuner up this way, he'salways building silly power track cars

I can pass you his details if you want to fire some questions his way

[Miggs]

Oh and I'd go for head bolts over head work as too much power with standard head bolts may cause them to stretch too much, at least with them done first you can sort further mods at a later date, maybe get all required parts for the build up first and leave external parts till a later date

[Miggs]

EJ22 Phase I: Found in Legacies
from 1990-1998 and Imprezas from 1995-1998. Comes rated at 130hp and
137 ft-lbs, 135hp and 140 ft-lbs, or 137hp and 145 ft-lbs.

EJ22 Phase II: Found in Legacies in 1999 and Imprezas from 1999-2001. Rated at 142hp and 149 ft-lbs.

EJ22-T Phase I: Found in Sport
Sedan and Touring Wagons (Legacies) from 1990-1994. Turbocharged and
non-intercooled. Rated at 160hp and 181 ft-lbs. Closed deck, cast
pistons, forged rods, oil squirters: turbo motor. Poor flowing heads.

EJ25 DOHC Phase I: Found in
Legacies from 1996-1999, Imprezas in 1998, and Foresters in 1998. Rated
at either 155hp and 140 ft-lbs in 1996 or 165hp and 162 ft-lbs in
1997-1999.

EJ25 SOHC Phase II: Found in
Legacies from 2000+, Imprezas from 1999+, and Foresters from 1999+.
Rated at 165hp and 166 ft-lbs. There was a slight compression ratio
change from 1999-2000 where it went from 9.7:1 to 10.0:1.

USDM EJ20: US Domestic Market
WRX. Found in 2002+ WRXs. Rated at 227hp and 217 ft-lbs. Turbocharged,
intercooled, open deck, and decent heads.

EJ25T DOHC: Available in 2004
in the Forester XT. Rated at 210hp and 235 ft-lbs. Turbocharged,
intercooled, VVTi (Variable Valve Timing), and drive by wire.

EJ25T-STi DOHC: Available in
2004 in the WRX STi. Rated at 300hp and 300 ft-lbs. Turbocharged,
intercooled, AVCS (Active Valve Control System), drive by wire,
intercooler sprayer, and semi-closed design.

There is also a large variety
of engines available from the JDM and EDM locales. The EG33 from the SVX
and the EZ30 from the new H6 Legacy can also be found, but they are
larger and will be more difficult to swap.

 

 

Until proven otherwise, the
exhaust from a standard WRX from 1993-2004 has remained relatively
unchanged.

There are four types of downpipes available from any of the
EJ20 equipped cars: the twin-turbo downpipe, a la GTB; the twin-scroll
downpipe, a la STi Ver. VIII; the IHI flanged downpipe from a pre-MY01
JDM vehicle or post-MY01 non-JDM vehicle, a la USDM WRX or STi Ver. VI;
or finally the IHI flanged downpipe from a post-MY01 JDM vehicle; a la
STi Ver VII. The twin-scroll downpipe can only be
used with an IHI twin-scroll turbo. The pre-MY01 JDM downpipe is the most common
downpipe used with EJ20 vehicles. The post-MY01 JDM downpipe was
introduced with the GG/GD chassis and is a few inches shorter than the
pre-MY01 downpipe.

If you choose the pre-MY01,
then you must mate it with a similar system. It can be mix-matched as
long as it is not matched with a post-MY01 JDM system; this includes
using cat-backs designed to work with the EJ25 engines. If you choose
the post-MY01, then you must mate it with what is commonly referred to
as a "JDM cat-back". The flange at the axle was rotated on the GG/GD
chassis so the mid-pipe and the axle-back must be from the same chassis
generation. Obviously with the beetle this may all be irrelevant to you as these details are mainly for swapping form subaru to subaru but it gives you an idea of what's on what.

 

All EJ series engines share the
same bolt pattern on the bellhousing. While some use fewer bolts than
others, they will still bolt up.

One caution: the turbo
transmissions use a pull-style clutch whereas the NA transmissions use a
push-style clutch. If you are swapping transmission types, you need to
match the transmission up with the correct clutch/flywheel assembly.

One more precaution: if you are
swapping in a transmission, you need to be sure that your rear
differential final drive ratio matches the final drive ratio of your
transmissions. Installing a new transmission without checking this could
permanently damage your center differential! Putting an engine from a
FWD car into an AWD car or vice versa does not change the swap criteria
as it will still all bolt together.

Thirdly, the older
transmissions use a different shift linkage joint attaching to the shift
forks of the transmission. The older transmissions have a fork that
attaches to the rest of the shift linkage whereas the newer
transmissions have a barrel joint. This must be updated if you are to
change from an older tranny to a newer one or vice versa. It is believed
that the older style shift linkage was used up until 1997. Beyond 1996,
the transmission linkage should be the new style.

Finally, the older
transmissions utilize a stud on the transmission for mounting the lower
hole of the flange of the starter. If you swap in a newer transmission
onto an older block, the block will not have the threads for the lower
starter bolt. Some have reported success with just using the upper
starter bolt, others have tapped a hole into the block.

Again, you are NOT doing subaru to subaru and from what i know you just use an adapter plate and mate the beetle box to it, not sure what you are and are not using so the info is there if you need it.

 

 

 

basically what i have found is the forged parts fitted as standard are the rods not the pistons, the engines are good for the power without using forged pistons but if you want super reliability and possible more power at a later date i'd probaby strengthen as much as i could while it's out and being done.

[Gambit]

:o I never knew you was religious. Posting the bible :)

[Miggs]

Sorry just trying to give as much info as possible

[Gambit]

I'm not complaining lol  Made me laugh how long took me to get to the bottom of the post :D

[Miggs]

That's why I didn't want to be doing it on my phone, Battery doesn't last that long lol

[Dubber91]

Wow, ok that's really helpful.

So an sti block with (possibly) forged pistons and updated head bolts looks like the consensus. Ancillaries wise a td05 with charge or inter cooler and aftermarket ECU is the go. Anything else I should do?

[Miggs]

The sti if complete should have the td05 and if that's the case you will be able to use stock ecu and loom, there's plenty of info on other stand alone management options within the vag community due to all the mk1/2/3 golf's getting mk4/5 engines, an intercooler is as good as charge cooler for cooling, but as it's in a beetle the charge oiler doesn't need to be front mounted, if you were taking it on the strip you can fill the charge cooler with dry ice for a nitrous like boost

Other than that, at the moment, that's all I can think of, if you can find a rear shunted import you will get most of what you need from that

Oh and a walbro 255lph pump at the least