View Full Version : down pipe
666nck
29-01-2006, 20:46 56
i wana get a de-cat down pipe off ebay,will the lamda sensor still run ok or eill it fcuk my engine up..:character0110:
The catless downpipe should have a plug hole the same as the STD cat one. Just a question of Lamda out fit downpipe Lambda refit.
666nck
31-01-2006, 20:38 57
ok thanks bob
pimpalicous
31-01-2006, 21:15 18
how much difference do these cat,less downpipes make really? thinking of getting one how hard are they to fit?cheers
beachsleeper
31-01-2006, 21:45 47
how much difference do these cat,less downpipes make really? thinking of getting one how hard are they to fit?cheers
Well you got 5 bolts at the top where it bolts on to the turbo and 2 bolts at the bottom. The bottom bit is easy its the top bit that you may find a bit harder, the bolts are tight and some are best got at from under the car. Nice if you can use a ramp. Out off all the exhaust mods you can do, changing the down pipe to a Decatted or sports cat down pipe will give you the most power gain. Bear in mind, Mot time.
scoobyDAZZA
31-01-2006, 21:47 05
made a heck of a difference on mine but i would personally advise a re-map after fitting 1
easy to fit if you know how
i got stung for 4 hours labour to do my 1st one , , but i know blokes who can do them in 45 minutes or less,so long as theres no problems,sha66ed nuts/bolts etc
good idea to lag it as well
Neil G
01-02-2006, 09:23 10
Did mine in no time but had been off before so none of the bolts were seized.....bit awkward though.
Olly P
01-02-2006, 17:38 22
I was still doing mine at 2.00am, I'm sure the neighbours loved it. Much colourful language in the air, and it carries well at that time of day.
An example of how bad it can get:
My brothers Legacy was being mapped and they were stuggling to acheive a decent boost level.
After further checks it was discovered that the cat in the downpipe (same as Impreza) was causing alot of backpressure. So much so the turbo was having to produce 1.5bar to see a real 1 bar. Removal of the cat cured it straight away.
Bearing that in mind, every cat will produce some unwanted backpressure, which will mean the turbo to a greater or lesser extent is having to produce more boost than you actually see.
So, when you de-cat the Scoob you will automatically get an increase in boost, but the ECU doesn't compensate (at least on the early ones)
The fitting of an uprated fuel pump will compensate for this. (more flow)
Anyhoo thats what I did with mine and it was fine.
scoobyDAZZA
01-02-2006, 17:49 41
yeah
what he said
:lol:
Agree....:lol: :lol: :lol:
666nck
01-02-2006, 21:26 33
I was still doing mine at 2.00am, I'm sure the neighbours loved it. Much colourful language in the air, and it carries well at that time of day.
An example of how bad it can get:
My brothers Legacy was being mapped and they were stuggling to acheive a decent boost level.
After further checks it was discovered that the cat in the downpipe (same as Impreza) was causing alot of backpressure. So much so the turbo was having to produce 1.5bar to see a real 1 bar. Removal of the cat cured it straight away.
Bearing that in mind, every cat will produce some unwanted backpressure, which will mean the turbo to a greater or lesser extent is having to produce more boost than you actually see.
So, when you de-cat the Scoob you will automatically get an increase in boost, but the ECU doesn't compensate (at least on the early ones)
The fitting of an uprated fuel pump will compensate for this. (more flow)
Anyhoo thats what I did with mine and it was fine.
mine is a v1 wrx 94L 240bhp so is it a pain 2do on mine will i need the ecu re-mapped????:mad0245:
First job I do on my scoobs is rip the cats out... most of them have been remapped a few weeks or months after but a few were never remapped. I had no problems....:smile:
Neil G
02-02-2006, 09:52 25
mine is a v1 wrx 94L 240bhp so is it a pain 2do on mine will i need the ecu re-mapped????:mad0245:
I decatted a 94 WRX and didn't have it mapped.....ran fine without any issues
Olly P
02-02-2006, 13:43 35
I didn't have a remap either.
I was just told to put in a bigger fuel pump at the same time as de-catting.
Neil G
02-02-2006, 14:17 49
I didn't get round to doing the fuel pump and regulator
Olly P
02-02-2006, 15:10 54
Mines still on the standard regulator.....bit of myth that one.
pimpalicous
02-02-2006, 21:09 52
cheers guys will order one tomorrow with a uprated pump from flat4online.what are the de-cats like from ebay anyone know? and also what is the best type of bleed valve u guys have found for upping the boost?and where to get it from and how ££? cheers chris:smile:
pimpalicous
02-02-2006, 21:10 42
Mines still on the standard regulator.....bit of myth that one.
does that need changing aswell when these mods and boost is upped or not? wanna makes sure i do it right so my engine is safe
My standard reg was ok to 320 bhp. I only fitted a new one because of the 382 bhp and 2.5 engine.
pimpalicous
02-02-2006, 21:20 35
okay thanks bob :smile: so with the uprated pump,and the boost upped to 1.0 bar and both de-cats done,arc super induction box,and full hks exhaust system done i should be seeing about 300bhp yeah? will this be safe for the engine? as i like to drive it hard
I cannot say it will be safe M8. I have seen tons of Scoobs with blown engines standard as much as tuned. Most Scoobs that have gone bang are ones that have just been service and ones that are held in top gear on full throttle and very near the rev limiter.The scoob seems to me to be a sprint car.
My scoob went bang at 150ish mph @ nearly 8000 rpm. I think Derek's was revving even higher..:frown:
pimpalicous
02-02-2006, 21:29 54
im gonna take it if i tune it i shouldnt spank it as much as i do as obviously there is alot more strain on the engine i suppose not turning up the boost would help alot with the whole reliability issue may consider not doing that
Saw most differant types of Scoob on the track being ragged round all day. But they don't hold max revs in top do they....:cool:
It is well know that after about 100 mph the scoob scoop becomes next to U/S as the air bounces over the top of it. At this speed the inlet temps will rise rapidly and if the car is held at high speeds the turbo will overheat causing hot air to enter the inlet and Bang. When the scoob is ragged round a track it does hit sometimes 130 mph or more but it is not held there you slow down for corners giving the turbo and inlet temps time to cool...
pimpalicous
03-02-2006, 00:49 15
so im taking it a front mounted intercooler is quite i wise option,what kinda lag do u experience when u fit a front mount intercooler is it quite noticable or ...?
If you drive at over 100 mph a FMIC is a good investment...:wink:
You would be surprise the differance it makes to the inlet temps.
I never noticed any differance in lag. The only time I had lots of lag was when I fitted a VTA HKS dump valve. This stayed on for 4 days then a Recirc dump valve was refitted. No lag again.
pimpalicous
03-02-2006, 01:30 47
oh ive just bought a hks sequental dump valva just waiting for it to arrive! lag here i come!:hysterical: im a bit worried about running the 1 bar of boost with my mods and the boost am i not gonna be over powering,boosting the engine past the internals limits or...?
sorry for all the questions just trying to get all me knowledge up on the car and then decide what to do!
Just answered this on your other thread....:hysterical: 1 bar of boost for your Scoob is nothing. If you do not go over the Fuel cut the ECU will handle the mapping.
Left my HKS VTA at Tiley's workshop...:rolleyes1: I did get lots of swooooosh and pops and bangs but found the car surged when trying to hold steady on the motorway. When changing gear thought I was in to high a gear with the amount of lag I had.
pimpalicous
03-02-2006, 01:49 41
Just answered this on your other thread....:hysterical: 1 bar of boost for your Scoob is nothing. If you do not go over the Fuel cut the ECU will handle the mapping.
sorry just abit scared of blowing me engine up! has happened to me a few times!hmm not looking good for my dump valve then! :hysterical: will try it if its crap will sell it on i suppose.
Some lads get on very well with the VTA others like me go back to recirc.
Neil G
03-02-2006, 09:54 29
IMHO recirc defnately best.....had a VTA but car ran much smoother and quieter with the OE one back on
pimpalicous
03-02-2006, 11:43 43
well i will just give it a go and see how it affects the car
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