The AUSubaru.com.au Forums

A post earlier today got me thinking....

With the extra insurance of an intercooler and a free flowing exhaust, along with 98 premium (EA82T was designed for 95 i think), to gain power, would i be better off....

to increase the boost and take advantage of the increased knock resistance of the fuel? (we will assume that we increase the boost to just before the point where knocking would start to decrease the ignition timing )

Or... leave the boost as factory and increase the base ignition timing up to the point where it starts to retard, to take advantage of the extra knock resistance?

Example.....

Factory engine ran 7psi of boost and at full load ran 20deg BTDC ignition timing

1.) so if i increased boost to say 9psi and the 4 extra points of RON, meant the ignition timing stayed at 20deg BTDC under full load.

2.) i left boost at 7psi and increased base ignition timing by 3 degrees, so that at full load it ran at 23deg BTDC and the 4 extra points of RON, meant the ignition timing didnt retard.

Which one would make more power/torque?

The one with more air, or the one with more ignition advance

(please note, all figures are all hypothetical)

I always run all of my EA82T @ 20deg BTDC.

My RX I ran 14PSI (With air to air IC) on E10 for 2 1/2 years with no problems. I then rebuilt the motor (Didn't need a rebuild but it was going in to a car I needed to be reliable)

Boost is the easiest way to increase power......

Gannon,you have near 2000 post,s..amd your still asking q,s on ea82t power....
Extreme RX is from the world i know..and has around 800 post,s..and is giving you sound advice...

Can you see the tree,s? or is the forest blocking your view?

Relax dude..your on the trail of the quark.

Im not actually looking for more power, i was just toying with the idea that maybe there are equal gains to be had from increases in ignition timing, as opposed to boost.

Part of this idea came from discospuds notion that increasing boost past what Subaru intended can have detrimental effects on power output, mostly caused by higher pre turbo exhaust pressures.

Im still waiting for Adrian to give his opinion.

Gannon the point I made in the other thread was that if people want to have factory reliability and longevity without changing anything significant simply screwing the boost up can cause problems .

You've mentioned said that you're making a better header and already have a more modern dryer that Subaru used . Your exhaust from memory is better than std as well .
Doing these things properly is where you make gains without altering boost pressure . Whenever you remove exhaust side restrictions , assumes you don't go too big , you change the whole world the engine see's . When it can "breathe out" more easily it has less pumping losses (crank power wasted pushing exhaust gas out the exhaust ports past avoidable restrictions) and the combustion efficiency usually improves meaning a few more degrees of timing may be possible without chronic detonation .
Intercooling is good because it reduces the charge air temps and all else being equal this reduces combustion and exhaust gas temps .

Your call Gannon , if it were me I'd concentrate on that header .

Actually one more , its surprising how many people don't realise that changing ignition timing changes air/fuel ratios .
Detonation can be caused by different things and its best to know which it is so you can do something about it with the least number of disadvantages .

Cheers A .

One more Gannon , if you're really interested in turbocharging have a look at Corky Bells book Maximum Boost ISBN 0-8376-0160-6 .

This goes into all sorts of engine related things that would probably interest you .

A .

if you want to get more timing into it look at water injection there are some flash systems out the that use the poost from the manifold to "pump " or pressurise the water into the manifold before the turbo cooling the mix and reducing detonation

Well water injection is something i has crossed my mind.

Some of you may have missed the point of my thread (i probably could have worded it better) Im not actually looking for more power, i was just thinking that there are other ways of increasing power without increasing boost (as too much boost will shorten the life of the EA82T)

What i meant was....

If the standard EA82T made 115HP on 95RON fuel and 7psi
And upping the boost to 10psi makes say... 130HP on 95RON
Should i aso be able to achieve close to 130HP with 7psi, intercooling, more timing and 98RON fuel?

Yep designing that header is on my to do list

Keep the comments coming, think of it as brain storming

You guys are crazy... Its that easy to put a 130hp EJ22 in and they run all day long reliably..

But this is more fun.

had a close look at a Forester GT on LPG today ...it got me thinking, sell everything and just have one vehicle - but it ain't no ute so stick with what I got. Nearly got me though

Suparoo wrote:But this is more fun.

+1. this is why im going back to turbo for the next sooby.

So why not put a 130hp EJ in, then turbo that.. You get reasonable reliability and more power. tehhehe

You will get good gains from a header, I made one years ago for my old EA82T, will make another for my new EA82T. Ill try and find a pic if you want a look.