Volkswagen Mark IV Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
59 Posts
Discussion Starter · #1 ·
Hello everyone,

Right then, i got a revo stage 2 the other day and i'm running full boost- ie level 9. when the car's cold, and occasionally when it's warmed up, if i accelerate, the turbo shoots from 5 to about 15 psi, but with no effect on the power of the car, and then it just suddenly kicks in...feels quite lumpy as a result. u can here the turbo spooling up fast, and on the boost gauge it shoots up like i said. it almost feels like what a slipping clutch feels like (power but with no delivery)...but obviously the turbo isn't slipping! anyone got any ideas? if u need extra info/explanation, then ask and i'll get back quick! quite keen on knowing what people think! could it be too soft a spring in the actuator maybe?!

cheers
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #3 ·
oh yeah sorry, no it usually spikes about 23psi, the runs around 19...pretty solid. but as i accelerate (in 3rd usually) from low revs, the boost gauge is showing a quick increase from 5-15psi, and then it kicks in, and goes up nicely (normally) from 15-23ish, and i get all that boost!

hope that helps a bit! it's quite hard to explain, but the analogy of the clutch is quite a good one i think...feels like a clutch slipping ie revs going up, but little/no engine power...turbo spooling fast but with no actual boost to the engine!

cheers
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #6 ·
nah it's definitely not the clutch...it doesn't feel like the clutch is slipping, it's just a certain rev range where the turbo spools up quicker than usual. the revs don't go up fast, just the turbo pressure, and i can hear A LOT of air going through the turbo! sounds awesome, but isn't doing anything, so i think it's not doing any good for the engine/turbo! i'm thinking the spring in the actuator might be too weak, so it's not holding the boost, but the turbo is spooling. does this sound right or have i just made that up?!
 

·
Registered
Joined
·
233 Posts
Are you only making 234bhp at 15-23 psi?

Maybe possibly a boost leak somewhere? remember your only making 234bhp so i wouldnt really expect a big 'kick' when it hits full boost, and the standard turbo is tiny so its working it probably is working pretty hard.
 

·
Registered
Joined
·
233 Posts
I just didnt realise that 15-23 psi only gives 234bhp'ish on a ko3s. I think the OP is expecting a big 'kick' from it, but i dont think he's going to get one from such a small turbo....

Get a bigger turbo on there, it will be ALOT more efficient, and more power. You wil not be pushing it so much aswell to get the same power.
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #11 ·
i don't expect a big kick from it, i'm saying that when the boost actually kicks in, i get a kick, but it feels a bit bumpy as there is this boost that has built up and then it feels as though it suddenly takes hold and pumps into the engine! very strange. the pull on it at the moment is ridiculous. 286lbs/ft of torque and 234bhp are awesome figures to be getting out of a k03s. got a feeling i may be running the boost a bit too high, but the guy who mapped it said that it was safe, so i'm happy to be honest. and this problem is mainly only when it's cold. once it warms up it happens very occasionally. i was thinkin about the n75. might have to change it. it's mainly coming from low revs in 3rd, uphill, but happens on the flat as well.

cheers
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #12 ·
also, 'getting a bigger turbo on there' isn't really feasible...no funds!! haha. and i'm happy with the figures i've got now...it's powerful, but the delivery is beautiful...other than this little mishap, i get a really smooth power delivery and it holds right through! feels great. that's why i notice this 'lump' so much!
 

·
Registered
Joined
·
233 Posts
Ah right cool. That might be good power from ko3s. I have a 1.8t as a daily but not too clued up on it, its reliable as fook thoh had it over 5+years with no problems what so ever. Recently not so long ago changed jobs and do 500ish miles a week.

To the OP, if its aftermarket spring loaded type blow off valve your running, possibly the spring might be wrong one for lower psi?? thus just opening when your hitting high boost leaking. I know i had problems with my spring on my tial blow off valve on my Civic type-R.
 
1 - 14 of 14 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top