john banks

If you have a standard or Prodrive modified car you don't need any of these bits. If you want to push things to a rather more interesting level of performance (I approximately doubled the output of my standard engine) then as you eat into the safety margins you need to monitor more to do all that is preventable to keep the engine det free and the temperatures controlled. Those who make substantial modifications without attending to these things are at high risk of losing an engine in the sub 300 BHP range, and are virtually certain to lose an engine prematurely above 300 BHP, then they are likely to say that Subaru engines are weak. It is not just a case of whacking up the boost and hoping for the best to almost double the power of an engine as I am sure you are well aware. So it is not doom and gloom, but common sense and a lot of TLC for such a highly stressed engine. You will note that all those who have pushed these engines successfully beyond 300 BHP in recent years and obliterated the earlier ideas that these engines were weak above that figure have all been careful to avoid losing an engine over something so preventable as detonation. You may wish to consider the effects of detonation on engines running high specific outputs.

[Edited by john banks - 10/1/2003 9:18:38 PM]

misty

I've only been on S.Net for a couple of months now but it seems every other thread is about how easily your engine will explode! It seems we all need a DAWES??, a KNOCKLINK??,or some other device to help us keep the engine safe. How, if this is the case did Subaru manage to win the J.D Powers survey for reliability two years running? And, why do they not fit such equioment at the factory if it is so important? When I served my time as a motor mechanic 30 years ago, we were always told most manufacturers build in a 25% safety margin on their engines. If that still applies today then, as most upgrades stay within that margin, why the need for all this extra equipment. perhaps it's a rumour started by the makers of such equipment to make us spend pounds and pounds on their gear? To finish off with, how do all the non S.Netters, sleep at night knowing (or more to the point NOT KNOWING) that their engine is just one knock away from oblivion.
P.S. This is in no way decrying the technical knowledge of the few who do give their time to answer these difficult questions only an observation from an old qualified ex-mechanic!
dave

mista weava

not an expert - but i guess it is an attwempt to minimise the prospect of something nasty happening after tuning at relatively lesser cost then re-build.

in the case of having devices on standard cars beats me??

maybe oil temp and pressure as an additon on the older models, where this does not feature as standard, but as goes for the rest of it on a standard car ???!!!??? dunno!

maybe people just like to know exactly what is happening as piece of mind?

i have modded my car - full de-cat being main thing. i have the scooby ecu to go in, but will be fitting boost gauge, oil temp and AFR along with knocklink, plus walbro fuel pump and regulator.

my arguement is that because i have interfered with the car, it is a wise choice.

on as standard car i doubt i would bother.

Weava

greasemonkey

I'm sure I'm at least as "guilty" of chanting the "safety first" mantra as anyone else. However, I think you've grabbed the wrong end of the stick with both hands, and given it a good yank here.

We don't all need them. Anyone running a standard UK market car should be fine. It's the Japanese imports and modified cars on which bits like this should be considered essential safety devices.

BTW, what "Dawes" are you referring to? The Dawes manual boost controller (aka "Dawes Device") is nothing to do with engine safety, it's a cheap and effective way of running higher than standard boost levels.

However, if you're referring to the Dawes AFR meter, it's certainly a good idea to run one, along with a KnockLink, if you've made any modifications to the engine, induction or exhaust. These two devices together will give you confidence that your engine is still performing within safe parameters. In this case, ignorance is definitely not bliss.

Probably because most of respondents to surveys like this will be Joe Numpty in his bog standard Scoob. These cars are very reliable if left standard and serviced properly, and in this state very few spontaneously combust. However, Scoobynet is an enthusiast's forum, and it goes without saying that a lot of readers will be running modifications, imported vehicles or both.

Because the cars are mapped to run within safe parameters at the factory. The potential problems start when you go beyond factory conditions, whether it be by raising boost levels, or using fuel that could be as low as 91 RON in cars expecting 100 RON...

Because there's a big difference between a correctly designed, correctly applied upgrade, and an incorrectly designed one. Devices like the KnockLink and AFR meter give a visual confirmation that all is well. Much better, ultimately cheaper approach than crossing your fingers. As far as your "25%" rule goes, there are plenty of cars running percentage increases well in excess of this with total reliability. Equally though there have been cars with smaller hikes going bang. The common denominator in many such failures is undiscovered detonation, hence the continual recommendation for KnockLinks.

Do you seriously believe the sob stories of expensively blown engines that appear here periodically are invented? If so, it's not even worth offering a reply.

Erm, they carry on in ignorance. The ones who run bog standard cars probably have no reason to worry. The ones who fit nasty boost clamps and other ways of achieving quick power hikes will be obvlivious until something goes wrong.

Still don't quite see your point. You are quoting people out of context by implying that these things should be fitted to all turbocharged Imprezas, so to a certain extent you've got the wrong end of the stick. On modified cars, or imports that are being run on fuel other than what they're mapped for, the reasoning behind these devices has been discussed at length many times.

[Edited by greasemonkey - 10/1/2003 8:30:33 PM]

misty

Greasemonkey. I wasn't pointing the finger or making false statements, it's just how I see it. Are you suggesting that as I have a prodrive modified car I need these other bits? No i don't believe that people on here tell lies, You have to see it from my point of view, and that is, I buy an excellent car, thats been properly modified in a way I personally could not have afforded to do! only to read articles that put the fear of god in me regarding the integrity of my engine. Please try to see it from an "older" subscriber to the cause.that "the only good car is a fast car"
regards
dave

EvilBevel

GM... according to a few dealers I spoke to at length (and 4 years plus of reading BBS's...): about as many standard cars go bang as "modified ones" do.

Of course, a badly tuned one will have more chance of going pear shaped, no discussion there, but don't underestimate the number of standard cars that go to engine-heaven.

So yeah, a knocklink and AFR make sense on standard cars as well If only to see when (not if) your MAF is going.

Theo <counts shares in knock/AFR gizmos >

greasemonkey

If by "Prodrive modified" you actually mean the PPP, correct, if you haven't made any other modifications and have your car serviced regularly there's no pressing need for devices like this. The PPP ECU's carry better engine protection features than "normal" ones, while proper servicing should catch any other potential danger - like a failing mass airflow sensor for example.

The problem here was your assumption that these warnings apply to all cars. One of the reasons why the PPP preserves the warranty is that it has been thoroughly researched and its power increase is known to have been derived safely.

This is not the same process that many owners take when modifying their cars. Many bits tend to get enthusiastically tacked on without thought being given to potential negative effects. Additions as simple as an aftermarket panel filter and decat exhaust can, in certain circumstances, promote operating conditions sufficiently out of parameter to cause serious engine damage.

Even altering the actuator restrictor bore - a modification that can be made for pence - can give useful increases in turbo spool, but cause huge engine problems if its effects aren't monitored properly. It's in cases like this that gadgets like KnockLinks and accurate boost gauges can make the difference between a safely running car and a grenaded engine.

Can see where you're coming from, but still think you've overgeneralised. The distinction between a truly standard car (or one with a recognised "safe" kit of mods like the PPP) and "the rest" is very significant here.