mista weava

i hope someone can answer this question for me,

when i bought my wrx 93 wagon, the bloke told me off when i changed down the 'box as i slowed down. he said that i should avoid doing this as it strains the turbo if you use the engine braking. he also commented that this was one of the reasons that F1 gave up on turbos. older fella and seemed knowledgeable.

since then i have abided and rarely engage any sort of engine braking above 3k- 3.5k rpm.

is this wise or can i savage down through the box like i did in my 205 ??!!

i would like too

your thoughts?

cheers

weava

Brun

F1 gave up on Turbo's cos 1500 bhp was takin the pi55.
Taking your foot off the loud peddle at 70 mph in 5th gear could be described as engine braking, and there is no way to avoid that.
I would forget about it myself, but i also wouldn't savage my box.

mista weava

brun,

thats kind of you to reply,

the term savage is one that i use loosely!

what i mean is is it acceptable in terms of mechanical sympathy to use engine braking when going down thru the box.

i think he (the guy who sold the car to me) was suggesting that a sudden increase from say 3.5k in fourth, then to change to third to gain engine braking for a bend and making the turbo spin up suddenly to high revs, was putting strain on the thing. he advised against - but was he talking poo?

weava

davyboy

I am sure an instructor once said to me,

"dont use my gears to slow you down, use the brakes"

Brun

When going down the box i'm yet to get the turbo to spin up. It just won't happen. I show -20 psi on the gauge when going down.
(the gearbox that is)

Wannabe

remember brakes are cheaper than turbo`s and gearboxes so its best to use the breaks more, but i use engine break to, its hard not to when u get that buz round those country roads.

Simon

Brun

You're probably right Davyboy, but £70+ for a set of front pads.

ProperCharlie

if you don't go down thru the box won't you end up braking into a corner and then finding yourself in a pit of lag and have no power to get the car balanced thru the bend? Personally I change down quite vigorously when on a back road blast. plus it sounds good.

Charlie.

Pete Croney

Next time you see the old boy, poke him in the eye. Utter rubbish!! The turbo is driven by exhaust gas and you need a lot of it. You have virtually none on over run.

Brun, -20psi? An absolute vacuum, is -14.7psi so your boost gauge may be misreading a tad.

Brun

I'll have to have a closer look Pete. Good excuse to go out for a drive me thinks Maybe it's me not paying close enough attention to it. I tend to look closer at what it boosts at. It peaks at 15 psi and drops off to about 14 held. I suppose that would make the gauge 0.3 psi out.

mista weava

thank you all for wise words especially pete whos judgement i regard highly.

when tanning around the twisties i find that braking, then dropping into the right gear in advance of the corner, then powering thru the corner to be the obvious thing to do (slow in fast out). when doing so it is unavoidable to not rev the engine fairly hard thru engine braking, if you have your dander up, so to speak!

also it assists the braking, when you are hard on them. this is my preferred style at least.

i have to say i have been gradually disregarding the old fellas advice. i don't like to rev the thing TOO hard when doing so, but really needed the myth to be exploded to give me peace of mind.

i will have to go all the way to cornwall to poke the old giffer in the eye though pete! still some good roads down that way !!

he he!

ta guys, will be less conservative i certain respects, and will defo enjoy the car that bit more.

pete i am sorry to disappoint your bank manager, but i got a scooby sport exhaust, six month on previous car s/h off a fella my old man knows.

full system dowmpipe, decat and b/box for £350! a bargain!

peace

weava

dnb

Brun - look closely at the scales on your gauge. Mine (Autometer) has boost pressure measurements in PSI and vacuum measurements in mmHg. They are slightly different, so 20 mmHg on vacuum is about right according to my service manual.


1 bar = 14.5psi = 750 mmHG (approximately!!!)


[Edited by dnb - 1/11/2003 12:16:10 PM]