Paging the turbopetrolheads

I've never noticed any real issue. Maybe the tiniest drop in poke if it's a case of booting it away when congestion finally clears, but that could well be me being pissed off and wanting to get away more quickly than 225 bhp can manage in a big 'ol Volvo.

Depends on the car, whether it is intercooled, charge cooled, if it has a knock sensor in the boost control circuit.

On a simple system that doesn't measure knock or egt, performance wouldn't be down that much, but on something modern, it could drop boost by a third.

That's mostly what I would have thought, although... see other post.

Specifically my boost limited 1.8t. We were snarled up in Newcastle on Thursday for over half an hour. Once clear of the busiest stretch, the donk felt sluggish when trying to accelerate moderately briskly over roundabouts.

Actually, no; she felt slow. I put it down to heatsoak - warmish day, 95 RON fuel, warm air entering the engine. I was surprised at the difference.

After not very long at all at HGV speeds on the motorway, normal service was resumed...

Do you have a stock air box with cold air feed or a filter kit that sucks in hot engine bay air?

Did boost gauge read low? Some makes limit boost on manifold temp as high inlet air temp is recipe for detonation.

This machine is completely vanilla standard. No modifications to the intake whatsoever. As I recall, the air intake is in the near side wheel arch.

The low blows don't have a boost gauge, so, dunno. It *felt* like it, but of course, that's almost meaningless. ;-)

Sounds familiar, my old C900 which had the knock sensor in the ignition and boost control circuits, and as you say, after a period of idling/crawling when the engine was already hot, boost would be significantly down for a couple of minutes. The gauge would show little more than "base" boost (about 2/3rd of normal).

Wasn't helped that the stock intercooler had no airflow except a small ducted vent at the bottom and was mounted behind the passenger headlight.

All of mine have been fine.

Fraser

Goodo. So it's probably very much model or installation specific.

I mean, it stands to reason, except I didn't know how aggressive the ECU is with limiting boost. I wasn't expecting the difference to be so huge, either: the 1.8t only produces 0.5 bar of boost. On the other hand it's designed with boosting in mind...

Then again... after an hour of motorway cruising to suddenly spend 40 minutes in stop / go traffic with no cool-down, that would lead to something of a heat build up under the bonnet. ;-)

The Mondeo TD suffered from head soak, but her intercooler was mounted at the top of the engine. The 1.8t has a beautiful-looking intercooler, condenser and radiator installation at the front of the engine bay.

But it doesn't matter where the IC is located. If the car isn't moving quickly the IC isn't getting air through it.

A liquid chargecooler is better in this respect because it uses pumped coolant and a radiator to carry heat away so it is still more effective when the car isn't moving. Also, on the old C900, people used a small fiat rad fan on the side mount to draw air through when slow moving using a thermo couple to operate it.

Other people with top mounts like Scoobs and Celicas/Starlets have used either a water spray bar, or a CO2 kit to spay the surface of the IC and reduce temps.

Ahhha but it will...

Yes indeedy, but the location makes a difference as to how much heat gets into it. Mounted at the top of the engine means plenty of heat when not moving. At the very front of the engine bay isn't so bad. Plus at least one of the fans will be running almost continiously to keep the condenser cool.

I remember reading about chargecoolers and how very few machines have this set up. I seem to recall the main reason is cooling complexity and the small efficiency advantages.

Yes, and yes. Kits available for Saabs if deemed necessary... ;)

You tend to find they are used by sprinters and drag racers, where a lot of time is spent idling with a hot engine, followed by very short bursts needing everything available.

And less so with Saabs, but lots of unknowing Subaru drivers have these because it looks / sounds cool.

Can't think of a worse setup to get that problem than the Subaru top mount intercoolers like all of my WRXs and my Liberty B4. Add in our 45 degree celcius summers days and I would guarantee if it was a problem I would of felt it.

Fraser

Maybe yours is always like it! :)

I wish. Cold as a nuns nasty here this morning.

Fraser

Never noticed it in the Volvo. The merc suffers a bit.

Ahh mid winter in Perth. Like a nice spring in the UK :)