Old school 'hot ups' for modern Subaru

grump

grump

Senior Member
Joined
Jul 29, 2008
Messages
140
Location
Melbs - eastern suburbs
Car Year
2002
Car Model
Outback
Transmission
Manual
Back in the dark ages a punter could quite easily get more power out their engine by doing or having a few modifications done - eg plane the head to increase compression ratio, have the block bored out to increase capacity, fit bigger valves, a hot cam and polish the ports, change the inlet manifold and add multiple carbies, add extractors and a loud muffler etc etc.

I was watching an ep of "Wheeler Dealers" the other day where Ed got about 30 more BHP out of an old WRX by fitting a low resistance air filter element, fitting a loud exhaust, and having the ECU remapped, and this got me thinking about old school 'hot ups'. No-one seems to do that anymore, and I was wondering why.

Also I reckon that my old OB would be much nicer with 200Kw under the right foot. (150Kw would by ok too). So how do I do that these days?

(Funny thing is that the most that could be got out of a Holden grey motor (2.2lt in line 6, about 75BHP stock - about 55Kw) was about 175BHP, or about 130Kw, and then it would be for racing, not road use. My OB has the about the same size engine but makes about 120Kw stock standard.)
 
Maybe because most of those things are already optimized in modern engines?

e.g. look at the torque curve differences between the EJ251 and EJ253. Massive. The block is the same, just changes to the inlets, exhaust, valve train, camshafts. The maximum torque is almost the same, the duration above 80% of maximum torque is extended about 1000 rpm at the low end, and 1500 rpm at the high end in the EJ253.
 
Definitely not as much fun as tuning the twin carbies on my Cooper S and Range Rover by ear and checking dwell angles, point gaps etc
 
Agree @Kevin, but I haven't done any of that since I checked the tappets in my Impreza in about 1994 ...

Unlike my hot rod Morris 1100, where I did tappets, carbies, plugs, points, timing and oil change every 1500 miles. Had my plugs oil up after a 10-20 minute hold up in traffic ... Had to clean them with the car parked on the footpath! Had N3 plugs. Standard N5/N9Y were too hot.
 
grump said:
No-one seems to do that anymore, and I was wondering why.
Click to expand...
I guess maybe because modern engines (EFI) have much tighter tolerances than carb ones plus everything has to be coordinated with the ECU. I noticed also that the engines, especially the direct injection ones, keep getting more efficient but much less resistant to changes. Carb engines are tolerant to mods because everything is analog.

Ratbag said:
Maybe because most of those things are already optimized in modern engines?
Click to expand...
Yes. Modern engines undergo long-term incremental laboratory testing so if one will change to a high-flow muffler and a less restrictive air intake, even with a good ECU remap or dyno tuning, there is not guarantee that the engine won't give up even with such simple mods.

Ratbag said:
e.g. look at the torque curve differences between the EJ251 and EJ253. Massive. The block is the same, just changes to the inlets, exhaust, valve train, camshafts. The maximum torque is almost the same, the duration above 80% of maximum torque is extended about 1000 rpm at the low end, and 1500 rpm at the high end in the EJ253.
Click to expand...
It's amazing what they did to their EJ engines, actually. Those incremental changes are small yet significant.

Port polishing is still being done today, even to modern engines, but the car still needs to have the ECU remapped or dyno-tuned.

I just remembered that our first EFI engine is our 1998 BG5! Before that, we had carb Toyotas, Mitsubishis and a VW Beetle. The diesel ones were all injection-pump ones.

Our carb Toyotas and Mistubishis were tuned for economy and lesser emissions. They are very well-maintained to the point that during the 90's, they have more conservative emissions vs unmaintained EFIs.

My VW wasn't tuned for economy but as a streeter. I did a top overhaul, including port polish, and installed an open exhaust giving that extremely sexy boxer sound.
 
ABFoz said:
My VW wasn't tuned for economy but as a streeter. I did a top overhaul, including port polish, and installed an open exhaust giving that extremely sexy boxer sound.
Click to expand...
People used to say my '76 sounded a bit like a harley ;)
It's the one car out of all that my family had that I wish I still had. My brother's bright yellow 1800 DL('84?) was pretty sweet with it's black windows though. that car was ahead of its time. They wound up the suspension and toured a fair chunk of the NT in that back in the 80's. Probably one of the first outback touring Subarus in Oz. Well those and the '61 Kombi. Dang, we had a lot of cars now that I think about it. Nobody else in the family is in to cars any more. kind of weird really, considering the variety of cars we've owned. A surprising number of classics now that I think about it. I vaguely remember a Nissan silvia back in the 70's..
looked something like this:
1920px-Nissan_Silvia_CSP311.jpg


I wonder how much one of those would be worth now...
I remember listening to the Goon Show in it!

And that's my ramble for the day!
 
Ratbag said:
Maybe because most of those things are already optimized in modern engines?
Click to expand...

Plus the cost of doing these mods can be quite expensive and reduce the life of the engine most of the time!

As for the EJ251 and EJ253 - the biggest difference I believe is the variable valve timing system on the EJ253! Amazing what they can do when valve timing can be manipulated rather than static through the rev range!

I saw a doco ages ago about some fellas that have created electronic actuated valves - best performance right across the rev range and less rotating parts. Bye bye to timing belts and chains! I don’t know if it will ever see factory production though.

That WRX example has too many things changed at once to determine what was most effective. The subaru air filter and box setup is quite efficient until you’re calling for stupid power output, in which case you’d need to upgrade your bottom end anyway. Most pod/sports filters are a backwards step.

An exhaust that’s “less restrictive” is probably the only real viable mod to the NA EJ engine. Cam profiles can be messed around with to move the torque curve but that’s limited too. Then you’ll need a tune to make the most of the physical changes. Things aren’t so easy these days and you need more than just a screwdriver to adjust mixtures etc!

My 20c worth ;)

Cheers

Bennie
 
@El_Freddo Bennie, the EJ253 also has a MAP sensor rather than a MAF sensor (improves engine performance as altitude increases, among other inlet tuning improvements), tumbler valves in the inlet manifolds (significantly improves low rpm torque) as well as that variable valve timing/lift system, which improves both low and high rpm torque.

Very significant improvements from relatively insignificant changes.

I agree completely that many, if not most, modifications from standard lead to both reliability and longevity problems. Been there, done that, learned some expensive lessons ...
 
I believe the EJ251 is also MAP based and not MAF @Ratbag. The only EJ25 using the MAF sensor is the EJ25D from the late 90’s.

My sister’s RX liberty (1999 build, 2000 model) and my MIL’s SG, both EJ251, are MAP based engines.

Either way, most changes are an improvement as engine evolve through the models, be it physical or tuning.

Cheers

Bennie
 
Back
Top