GrahamG

What do you mean by that?

Cheers
G.

New_scooby_04

iTrader: (4)

If I understand it correctly, at higher speeds (over 100mph) the air basically misses the intercooler scoop. This means that the car is not longer getting the nice cool air into the top mounted intercooler it needs to keep the charge temps temps down. If the charge temps get too high, it leads to detonation, which can destroy your engine very quickly.

That's why the folks doing the high speed runs, swap for a front mounted intercooler.

Ns04

alloy

max hp doesn't come till 6800 revs, so i'll play happily up to there. Methodically warming up and cooling down, after all don't spend all this money to shaft your engine for the sake of a few minutes idle!!!

TRIPPLE: Shut it!! sensing some jealosuy there mate... . Whats the view like back there?

ALi-B

iTrader: (1)

Engine life is more or less directly propertional to engine load (i.e sustained full boost, full throttle). Rpm is not really significant unless it is sutained for any period on wide throttle and full boost levels.

No load or light load high rpm is different.

The problem is temperature. High engine temps kill engines (or too low as well), FACT. This is NOT coolant temp. Oil temp is much more reflective of internal component temperature, although still only a reference (so bin those Defis ). Obviously, power mods exasperate the issue. Oh and not forget the intercooler at 100mph+ issue either

UNder prolonged maximum loads the engines internals will quite easily go into thermal runaway, thus affecting tolerances and oil viscosity. Subaru engines, being alloy blocks don't have the best thermal stability as it is (one reason why the american still have a love for cast iron) and are well known not to endure prolonged abuse unless modified to endure it. This combined with oil thining down at high temps, accompanied by degradation thorugh continued usage in these conditions (by not changing it often enough!!!) will effectively reduce the egine life span.

It must noted Engine wear is Cumulative in other words, in most cases where your engien fails and blows up - it was during a "blast" down the mortorway or twisties, you'll instinctively blame that...wrong! Truth is, it was all the high speed "blasts" and short 5min journeys and lazy/incorrect oil change schedules (for the anticipated use) beforehand that did all the wear and damage...the final hard run just finished it off.

This is why your engine running top notch super duper racing spec synthectic oil, but regulary tracked and driven enthusiaticly and aggressively on public roads (i.e like a tw@t ), will NEVER last as long as pslewis's codger wagon running with cheapo comma semi-synth. And then you'll have to put up with Pete sneering at your own misfortune

Tripple'O G

So you're saying going by the oil temp still isn't a good judge of when to start using boost? what is a good measure then?

Alloy: Not bad........but you need to get out the way cause i'm sick of trying to go through you.... Liking the throttle control though

alloy

Trying is indeed the correct word

ALi-B

iTrader: (1)

What is a good measure?...Your head!

A gauge, by design can only be a rough reference...it depends where the sender is positioned..for example sump temperature is very different to oil temp inside a turbo bearing. So it can only be used as a rough guide. It's better than nothing, but you cannot say if you never exceed 100C on the gauge the engine will never let go

pnbond007

iTrader: (1)

So guy's
Your saying that my low geared 300bhp very well maintained MY93 WRX-RA with optimax & booster, is ok travelling at 70mph at nearly 4k & for long periods of time, or lets say covering 100 miles or so is acceptable, I'm not convinced.

I'm advised that these engines are not when fettled with, capable of sustaining long periods of high speed, the heat aspect is to much for the engine to cope with.

when running a full de-cat & induction system, surely everything is moving through the intake & exhaust system far to quickly, hence wrecking valves & burning corners from pistons.

PNB

Tripple'O G

My head?
So like 20 mins after starting Blue up?

I use my EGT as an indicator too.....the temps go up too high when motorway driving at anything over 4,500 rpm.....so I don't do it....

Alloy: Don't make be break out the video proof......

ALi-B

iTrader: (1)

High engine speed is different to load though. But it is proportional depedning on which gear your in

Due to the natural tendency of the turbo at 4500rpm+ in 5th you will be running well over 0.5 bar of boost ...in other words..load.

Rpm is proportional to load based on gearing. But load is the more critical. For example 4500rpm sustained in 2nd gear is very different to 4500rpm sustained in 5th gear. As in 2nd gear the thottle will be nearly closed and the manifold will most likely be under vacuum, rather than boost (less load, less heat, etc etc.).

If it was possible to maintain a constant speed of 3000rpm at full throttle (with a very heavy caravan ), you'd find that the engine would suffer more than one operated continually 5000rpm with a nearly closed throttle.

GrahamG

so do you think the new design in scoop is a lot better for that? Cheers
G.

New_scooby_04

iTrader: (4)

If you're referring to the MY06 model, It's not really the scoop that's made the difference, mate. It's the shape of the bonnet that has been changed to improve airflow into the scoop (which they've now made smaller).

The large scoops found on the previous MYs were a "band aid" to try and grab some more of the air that the bonnet was deflecting over the samller scoop.

Are you thinking of modifying a classic with a new age scoop?

NS04

JTaylor

Good post

Tripple'O G

DON'T PUT A NEW-AGE SCOOB ON A CLASSIC.....

Shocking and IMHO, down-right ugly......seen one down the Ace cafe.....really not nice (with it being sick)

dpb

^^ Hes got a point...!!

I had mine for a year an behaved like a total juvenille despite being nearly twice the age .. - but its the sort of car that brings out that element especially if youve never had the power/traction before . It was easy to find an excuse for going for a blast..!.......having said that i never got into ANY trouble in it.

JTaylor

and another

Accurate and well considered, whatever next

automodellistagt

I try whenver i can to avoid the short five minute journeys, to the shops etc but you cant avoid them completely. I dont tend to drive the car on a timelimit basis, some people on here have said 20 minutes, i tend to have some regular roads that i like to use, e.g. today ill drive this road, then ill go to blah via this road. The longest drive ive been on was, time wise, was ironically with a bunch of scoobies in sussex. Was a good hour of hard driving in the summer.

i allways figure that ill take as much preventative measures as possible, on-time servicing, warming up, warming down, but at the end of the day, your car may last 100,000 miles of ballistic driving, or it might have been a friday afternoon at clocking of time for the guy who was just finishing your engine.....

so sod it, take precautions but have fun with it. If i wanted to go slowly everywhere i would have bought a ctr :P

pnbond007

iTrader: (1)

Thanks for this reply,

One question: Would having variable boost control be a positive move & likely to be more economical on longer run's.

Economy is not a concern, engine protection is

PNB

ALi-B

iTrader: (1)

It wouldn't do any harm, although you'll never be able to get it to go below 0.5bar without fitting a very weak wastegate actuator and then you'd have problems maintaning peak boost when you do want it.