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Used Porsche and Prestige Cars For Sale | Harbour Cars

Standard K16 Turbo boost threshold & boost pressure?

R

RWD_cossie_wil

Spa-Francorchamps
Joined
13 Feb 2010
Messages
360
Evening all :thumb:

Right then, I need to pick your collective brains please, I'm getting the feeling recently that my turbo feels a bit laggy?

Where does the standard 996 turbo start to make boost? I seem to be getting not a lot until about 2800 Rpm, then 0.1-0.2 bar , which builds to 0.6 bar at about 3500rpm.

I am thinking the car probably needs a check over as isn't it meant to be 0.8 bar standard?
 
Should be 0.7 to 0.8 in perfect conditions.

Interestingly. Mine is doing the same recently, 0.6 to 0.7.

Am wondering if it's the fuel... Have tried Tesco momentum 99... Heard it was actually pretty good, but not convinced!
 
It is not the fuel!

Had this problem on mine, was an actuator sticking (waste gate was free but actuator dodgy). Now builds boost so quickly it feels like it has had a remap.

The problem crept up on mine, just kept thinking I was getting used to it. Less than half throttle mine registers 0.5 very quickly now, open a little more, 0.6-0.7 with 0.8 showing at the gear change (tiptronic). Occasionally shows 0.8 before this point dependent on ambient conditions.
 
Although i hadn't noticed anything different in the boost pressure (seems to hold 0.6/0.7 all the time currently) my NS actuator arm was snapped! This was removed and welded back together then refitted.

I've noticed differing levels of max-boost depending on the outside temps (ie a higher temp equals a little higher boost level) which i assume is to be expected? When i first ran the car last month with temps around 3 degrees i was seeing 0.6 solidly. Now seems to go a shade higher with the warmer temps.
 
DynoMike said:
It is not the fuel!

Had this problem on mine, was an actuator sticking (waste gate was free but actuator dodgy). Now builds boost so quickly it feels like it has had a remap.

The problem crept up on mine, just kept thinking I was getting used to it. Less than half throttle mine registers 0.5 very quickly now, open a little more, 0.6-0.7 with 0.8 showing at the gear change (tiptronic). Occasionally shows 0.8 before this point dependent on ambient conditions.
Click to expand...

Are you sure the actuator rods are adjusted correctly? 0.8 peak sounds a little high for a K16 non-remapped car.

But I agree, you should get a good amount of boost at half throttle from very low down the rev range - so low that you don't feel there's any lag.
 
eca02apc said:
DynoMike said:
It is not the fuel!

Had this problem on mine, was an actuator sticking (waste gate was free but actuator dodgy). Now builds boost so quickly it feels like it has had a remap.

The problem crept up on mine, just kept thinking I was getting used to it. Less than half throttle mine registers 0.5 very quickly now, open a little more, 0.6-0.7 with 0.8 showing at the gear change (tiptronic). Occasionally shows 0.8 before this point dependent on ambient conditions.
Click to expand...

Are you sure the actuator rods are adjusted correctly? 0.8 peak sounds a little high for a K16 non-remapped car.

But I agree, you should get a good amount of boost at half throttle from very low down the rev range - so low that you don't feel there's any lag.
Click to expand...

Only shows 0.8 in high ambient temps, but often shows it when changing gear. Remember that a tip changes gear at WOT, so engine speed is dragged down with the turbos still at a speed appropriate to 6500 plus. It only shows this 'spike' for about a second before reverting to 0.6-0.7.

Yesterday in 13 C ambients, peak full throttle was 0.6 with a 0.7 at the gearshift point. As far as I'm aware the actuators are set correctly, will pop it on a ramp and have a look at the cracking pressures when I get some time free.
 
Yeah, it could be a tip thing. Mines a manual so that could well be why mine doesn't do that and yours does.
 
In the interests of conducting highly scientific experiments to confirm Tip boost levels when using WOT (translation, "any excuse for a drive"), I've been out with the GF in the car on some of the nicer A roads around the Vale of Belvior. At 15 degrees ambient (according to the car's dash readout) my Tip held a solid 0.6 bar at WOT. Occasional spikes to 0.7 (very brief) and occasional drop to 0.5 during a gear change (i think - it's difficult to check the boost gauge and maintain a clean driving licence....)


Hope this helps. If there is any other reason for me to conduct similar experiments (perhaps someone wants to know the precise air temperature just south of Stamford on the A1?) I'm more than happy to pop out and check for you :drive:
 
911_Newbie said:
Although i hadn't noticed anything different in the boost pressure (seems to hold 0.6/0.7 all the time currently) my NS actuator arm was snapped! This was removed and welded back together then refitted.

I've noticed differing levels of max-boost depending on the outside temps (ie a higher temp equals a little higher boost level) which i assume is to be expected? When i first ran the car last month with temps around 3 degrees i was seeing 0.6 solidly. Now seems to go a shade higher with the warmer temps.
Click to expand...

As a norm lower temp = more boost, we have to be very xareful of the Supras we build because they run ceramic turbos that pop at high boost, if you run max boost in the summer you would have to lower the boost controller as the temp drops to stay safe. I reckoned my Supra would lose up to 100 hp on a hot day over a very cold day.
 
Whilst driving to work tonight - ambient temp 12.5 degrees, half throttle, the boost came on at 2400 and built to 1.1 bar before dropping to 1.0 at the gear change.

It's the first time I've driven it for a while as I've been on holiday but even 'pootling' at half throttle leaves you hanging on as the boost rises!

LOVE IT!

Mines a mapped tip by the way.
 
JohnnyDangerous said:
911_Newbie said:
Although i hadn't noticed anything different in the boost pressure (seems to hold 0.6/0.7 all the time currently) my NS actuator arm was snapped! This was removed and welded back together then refitted.

I've noticed differing levels of max-boost depending on the outside temps (ie a higher temp equals a little higher boost level) which i assume is to be expected? When i first ran the car last month with temps around 3 degrees i was seeing 0.6 solidly. Now seems to go a shade higher with the warmer temps.
Click to expand...

As a norm lower temp = more boost, we have to be very xareful of the Supras we build because they run ceramic turbos that pop at high boost, if you run max boost in the summer you would have to lower the boost controller as the temp drops to stay safe. I reckoned my Supra would lose up to 100 hp on a hot day over a very cold day.
Click to expand...

Does the 996T vary the boost level when temps get higher to maintain the power output? From what i've read it sounds like boost pressure increases slightly as temps increase, thus in summer i might be seeing a solid 0.7 bar instead of 0.6 etc. Or am i talking cobblers?
 
911_Newbie said:
JohnnyDangerous said:
911_Newbie said:
Although i hadn't noticed anything different in the boost pressure (seems to hold 0.6/0.7 all the time currently) my NS actuator arm was snapped! This was removed and welded back together then refitted.

I've noticed differing levels of max-boost depending on the outside temps (ie a higher temp equals a little higher boost level) which i assume is to be expected? When i first ran the car last month with temps around 3 degrees i was seeing 0.6 solidly. Now seems to go a shade higher with the warmer temps.
Click to expand...

As a norm lower temp = more boost, we have to be very xareful of the Supras we build because they run ceramic turbos that pop at high boost, if you run max boost in the summer you would have to lower the boost controller as the temp drops to stay safe. I reckoned my Supra would lose up to 100 hp on a hot day over a very cold day.
Click to expand...

Does the 996T vary the boost level when temps get higher to maintain the power output? From what i've read it sounds like boost pressure increases slightly as temps increase, thus in summer i might be seeing a solid 0.7 bar instead of 0.6 etc. Or am i talking cobblers?
Click to expand...

Colder ambient air temperature (within the relatively small range of altitudes ASL we all drive our cars at) = denser air molecules per unit volume = more oxygen per unit volume = better "bang" per cylinder = more power = more boost (as long as your intercoolers are really efficient heat exchangers, otherwise the compressed air, which by its very nature gets hotter the more compressed it becomes, is still "hot" when it enters the intake manifold and you get less "bang" = less power)

More boost does not always equal more power - keeping IAT's down is essential to more boost equalling more power ...
 
911_Newbie said:
JohnnyDangerous said:
911_Newbie said:
Although i hadn't noticed anything different in the boost pressure (seems to hold 0.6/0.7 all the time currently) my NS actuator arm was snapped! This was removed and welded back together then refitted.

I've noticed differing levels of max-boost depending on the outside temps (ie a higher temp equals a little higher boost level) which i assume is to be expected? When i first ran the car last month with temps around 3 degrees i was seeing 0.6 solidly. Now seems to go a shade higher with the warmer temps.
Click to expand...

As a norm lower temp = more boost, we have to be very xareful of the Supras we build because they run ceramic turbos that pop at high boost, if you run max boost in the summer you would have to lower the boost controller as the temp drops to stay safe. I reckoned my Supra would lose up to 100 hp on a hot day over a very cold day.
Click to expand...

Does the 996T vary the boost level when temps get higher to maintain the power output? From what i've read it sounds like boost pressure increases slightly as temps increase, thus in summer i might be seeing a solid 0.7 bar instead of 0.6 etc. Or am i talking cobblers?
Click to expand...

Witha DME you can view/log requested boost vs actual boost so it may well be clever enough to take various parameters into consideration but I stay away from the mapping side as im not that clever !!! :?:
 
JohnnyDangerous said:
911_Newbie said:
JohnnyDangerous said:
911_Newbie said:
Although i hadn't noticed anything different in the boost pressure (seems to hold 0.6/0.7 all the time currently) my NS actuator arm was snapped! This was removed and welded back together then refitted.

I've noticed differing levels of max-boost depending on the outside temps (ie a higher temp equals a little higher boost level) which i assume is to be expected? When i first ran the car last month with temps around 3 degrees i was seeing 0.6 solidly. Now seems to go a shade higher with the warmer temps.
Click to expand...

As a norm lower temp = more boost, we have to be very xareful of the Supras we build because they run ceramic turbos that pop at high boost, if you run max boost in the summer you would have to lower the boost controller as the temp drops to stay safe. I reckoned my Supra would lose up to 100 hp on a hot day over a very cold day.
Click to expand...

Does the 996T vary the boost level when temps get higher to maintain the power output? From what i've read it sounds like boost pressure increases slightly as temps increase, thus in summer i might be seeing a solid 0.7 bar instead of 0.6 etc. Or am i talking cobblers?
Click to expand...

Witha DME you can view/log requested boost vs actual boost so it may well be clever enough to take various parameters into consideration but I stay away from the mapping side as im not that clever !!! :?:
Click to expand...

This is kinda what i assume - that the DME is intelligent enough to increase boost when ambient temps reduce power (increasing boost within safe tolerances of course).

It's an electronic boost controller thus (i assumed) was capable of increasing the boost level just a bit to maintain 414bhp in hotter ambient temps.

Mind you, most of you lot have no idea what 414bhp feels like anymore.... :grin:
 
I had a similar problem. Turned out to be the actuator valve. £30 plus fitting. Right as rain now :thumb:
 
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