Hdi boost issue?

[ct-hdi]

Right... ever since I did a mid box to back box conversion I've noticed a fair bit of smoke under acceleration... I no they do but it seems a fair bit worse now... its generally at low revs accelerating hard.

I don't no if it has anything to do with the box conversion or not... The Turbo hisses quite loud but always has really so I don't think there's a boost leak... (I have smashed the cat out and have a Hoffman race pipe to a mid box and egr blank so just took it that the turbo will be noisey)

The boost gauge shows that on 'spike' it's boosting upto 20 psi then a second later drops to around 17/18 psi then as I rev engine up it drops down to around 15 psi but that's at around 4000rpm...

Is that about right? Or should it hold the 18 psi all the way through the Rev range or is it designed to lower boost pressure as revs increase?

I'm running a reduced/smoothed torque stage 2 map and was thinking the turbo pressure may be 2 or 3 psi low?

But want to make sure there isn't a problem first so if the boost is designed to drop as you get close to end of rev range then it's all good... still goes well though so i would have thought it was all ok

[ct-hdi]

Bump

[Toms306]

A straight through will be smoky, loud and whistly. And the boost will drop off at the top of the rev band as the tiny turbo is out of its efficiency range.

Cant comment on the actual figures though, as I've never bothered with a boost guage lol.

[HDi--Power]

You should be running around 20-21 or so psi on that remap so id say your boost is a tad on the low side

[Poodle]

What colour is the smoke?

It's normal to get a bit more smoke under hard acceleration with a midbox conversion because it takes less heat and gas velocity to blow the soot out, shouldn't be a lot more though. Whats the pipe diameter on that decat?

[ct-hdi]

The cat is the standard one with insides removed. ..

The soot is black... so to me points to over fuelling... my main concern really is whether or not the boost should hold all the way through the revs or if it does reduce the higher the revs

[Poodle]

I'd expect it to hold for a decent period, up to 3500 at least, but the turbo is heading out of it's efficiency by then and will struggle to provide the flow. That said, i've never sat and watched the boost gauge on a stage 2, so couldn't say for sure.

A small amount of smoke at low revs when accelerating hard isn't too much to worry about - a quick squirt of extra fuel will help bring the turbo on boost earlier.

[ct-hdi]

Will just have to keep a check on things... ive dropped Mr Whippy an email too regarding the mapping, to see if it has any effect on anything either...

It goes well enough so will just keep an eye on everything

[Poodle]

I seem to remember whippy maps cut all the fueling fairly early on, so that'd be why the turbo won't have the fuel to hold boost.