My cars not coming on boost till 4k its pissing me right off what ways can i reduce that 4 k to say 3k? The cars an rs turbo.

I have a large front mount GRS I/C
superchip
Piper t2 cam
stage 3 head
Lightened fly wheel
4x4 cossie turbo.

I think the main thing is the pistons im running as they have been skimmed to run higher boost

When i had the old standard t3 on it was the same 4k area.

I fitted a pipercross cone on today as well now its more like 5k when the turbo comes on boost

Any help

 

get it set up by someone who knows what theyre doing and fix the huge boost leak you've probably got

 

Lower compression dont make ANY difference to when your boost comes in, even though most people think so, so it aint that at all.

Im blaming either a cam with too much overlap, or a huge boost leak

 

i had it set up about 4 weeks ago at jamsport.
the piper t2 cam is about 4 weeks old ..really lost as to y it comes in so i got a blitz boost controler too.where u can adjust the gain etc..

The boost hoses are all tight aswell

well lost to whats going on with it would a smaller i/c help things?

 

bigger or smaller intercoolers honestly make little or no difference in reality, theory yes, but ive tried it, does owt

 

full boost by 4k or started to spool up at 4k?

 

what actuater you running mate?

andy

 

that isnt lag

 

No idea on that...

Full boost at the mo is about 5k with the cone filter on
With the standard air box it was 4.2k.

Just been out under the bonnet and noticed the bottom boost hose had a kink in so jublie clip around that now.

 

it makes a big diff what actuater you run, take it off and have a look, are you running with or with out the amal valve? and do you no what boost your running?
- 31 starts at about 7 psi and gives a nice smooth power curve, -34 starts at 14 psi and comes in late with a big bang hence the -34 will kick in later in the revs, and the piper cam will only kick in late about 4 rpm.. you need to learn all of the above to start to understand whats going on mate biger turbo means more lag and small turbo means hardly any lag, as t2 is boosting at 2rpm and t3 starts at 3/3 and a half and so on, then you get to t4 = big lag

andy

 

BOOST THRESHOLD

 

Yeh its a 1.6,The max boost i run is 22.4psi i have 2 settings that and 18psi..
the cars always come on boost around the 4k area even with the old kent cam and standard turbo..at the mo with cossie turbo and piper t2 cam it dont hit peak boost till 4.3k.
On my blitz boost controler ive been told to reset it as sometimes they mess up..ive changed the gain etc on the controller but with no difference in pick up time..

I have a -31 act fitted could this be knackered? its about 2yrs old..not sure on what make it is etc..

When i have my foot planted and watch the blitz controler it seems to hit 0.0 psi about 3.3k then goes up slow as in 0.1 0.2 0.3 etc i get around 4k area and thats when it starts to shoot up fast..

The car ticks over fine no worries there..ive checked all the boost hoses etc cant see anything wrong there.

Well lost to whats going on

Only thing i int changed is the atc and reset the blitz boost controler

Darren

 

 

Could be the mapping on the chip. If the ignition isn't right it will feel laggy as hell!

 

Only a superchip in there i been told

 

hmmmmm... my RSt hits full at about 3k in 2nd gear, 2.5k in 4th/5th

 

Indeed!


Why cant people actually grasp the concept of what lag is and what a boost threshold is?

fooking does my head in

 

SO TELL US

 

Between me, chip, and gareth, its probably been explained a 50 times on here keith

Very basically...

Being below the Boost Threshold is the RPM range where there is simply not enough exhaust gas to spin up the turbo.
(Ie when you boot your T4'd cossie engine at 2000rpm and fuck all happens)

Lag is the time it takes from foot mashed to the floor to when you got noticable boost, when you IN the boost threshold.
(Ie the very slight delay between mashing the throttle and decent acceleration when you boot a T4'd cossie engine at 6500rpm)

 

eh?










so me changing gear at 3k revs EVERY gear even when hammering it, is doing the car no justice what so ever??

 

Basically, it's similar to what old skool people refer to as being "off cam".

 

EXACTLY.

People say about turbo cars being laggy (when they mean boost threshold), then rave about Civic TypeRs etc when you "off cam" (which is exactly the fucking same) until 6k+ anyhow

Tosspeices

 

Keith, at some points in the rev range, no matter how long you stay there you will NEVER come on boost.


Take your T4 cossie at 2500rpm up a hill where its steep enough to keep you at 2500rpm in the gear you are in and floor it, you will NEVER come on boost.

Thats being outside the boost threshold, you are at a point in the rev range where there just isnt enough pressure in the exhaust housing of the turbo to spin it up enough to generate boost.



Do the same test on a hill suitable for holding you at 5000rpm off boost and you will find that when you floor it, nothing happens inititally, then after a second or two you get a load of boost, THAT is lag.


so the boost threshold is where in the rev range you can spool the turbo, and lag is how long it takes to do so within that threshold when you go from a closed throttle to an open one.

 

the parts you have used are all lag increasers ,are you sure that it was worse with kent cam and standard turbo. What kent cam are we talking about .A -31 with the correct amount of preload and pneumatic control does not have any affect to LAG compared with a -34 set correctly.Ecu's can have problems the cvh requires high advance in nasp mode, it is common for the presure transducer to fail in this area but be fine on boost .The affect of this is serious lag.Compression does affect lag .

 

Compression has very little effect on the boost threshold (although not "none"), but can make a moderate difference to lag.
A higher comrpession motor is better at emptying the cylinders (more pressure at TDC for a given swept volume) and hence gives slightly more pressure in the exhaust and also allows slightly more air to be taken in on the next stroke which also means slightly more gasses for spooling.

Its not a massive effect though TBH

 

if you say so chip not prepared to write an essay.
A turbo is driven by exhaust gas energy which is heat .
The principals of als is heat

 

Fair point, didnt mention heat, higher CR means working the fuel harder, which also generates more heat.

Would be much appreciated if you would write that essay mate, you obviously know far more on the subject than the likes of me do, it would be a really useful thing to have in the technical archives section and im sure lots of us would be able to learn a great deal from you.

Weird that you say ALS is all about heat though, surely its largely about flow as well, and the point of the ignition retard is simply to avoid over reving the engine?

Again though, an article from someone like yourself would be greatly appreciated.


Maybe something you could do for us all when you get a spare half hour?

 

You've got to love this site for some of the crap talked!!! lol

In answer to the original question, a 0,48 turbine housing with the likes of a piper T2 on a low comp 1600 will always be 4K+ before fitting full boost.

I would recommend you fit a new std cam and a 0.36 turbine housing with 50 trim compressor wheel if you want a nice punchy 200bhp 1600 engine.

Of course it will need a decent chip and setup, and the best person for the chip is Tony (Turbosystems) so give him a shout!!

 

chip compression has very little effect when on boost .
not only will it be a .48 karl I bet it also has a 7 degree cut back perfect if you want more lag

 

You lot with the techie stuff above! (excuse my ignorance! lol)

Least with the above he knows what to do now

 

very little effect on what?

Has lots of effect on the ignition timing requirements for example, so if its an off the shelf chip like most people use its a big issue to get the correct chip for the CR in question.

 

Mine don't kick in till 4.5k

Its the cam ...... i got a kent 35 in mine not out of choice just becouse it was in there when i brought the engine and it was newish ..... I am soon to be changing it to a 34 My .63 abarth housing don't help me either but when it kicks in it kicks

 

by installing oversize trubine housing on small capicity engines you increase the lag the net result is a car that feels fast but is actually slower.
Big is not best

 

just because the missus says so, hey Tony

Sound advice from above tho

 

I always go for small petite women
bit like small shoes they make your feet feel big

 

unless you have really big feet, in which case the shoes may just hurt

 

chip you best stop wearing your girl friends shoes

 

Cheers for all the advice..

When i first brought the car it had a kent cam and standard turbo i wasnt getting pinned into the seat entill 4.2k area..

Which still isnt far off whats going on now.even tho i have a different cam and bigger turbo..

When i had it set up the tuners quote was "have you got pistons in that engine"

 

LOL, well ive fucked a few of her girlfriends over the years, does that count?

 

Ive never heard of that before..this is my first turbo`d car

I sort of understand now