Maserati and vents ?!??!

[Raks]

Spotted a 51 (?) silver Mazzer in EC London with the Boomerang lights.
However, the car had fin like vents along the bonnet !??!

Cost option, or is this car hiding something ???

[mr_tony]

Standard 3200 has bonnet vents (one each side - 3 vents like 'gills') guess this is what you saw. I suppose they're there for the turbos to pull air in through as they have gone on the NA 4200....

[murph7355]

Cooling vents more likely. Pedantic mode on, but turbos don't pull air in (exhaust driven)...

[mr_tony]

shows what I know then!!

err hold on, [and probably showing my ignorance even more here...] but surely the turbos are driven by the exhaust (something ahs to make them spin round I get that bit...) - but I figured theyd draw in fresh air to the engine by their spinning - somewhat like a paddle wheel is that not how it works then?

I'm off to read up on this as I really should know how it works if I'm driving a car with two turbos....

[murph7355]

I'm also no techie expert on this, but I think this is the way it works:

The engine revs up and produces exhaust gases. These are used to spin the turbos which creates pressurised gas used to pressurise the inlet (the air coming in as it normally would, so the turbo doesn't pull air in - I guess you could say it pushes it into the engine, or force feeds it - ergo "forced induction").

The reliance on exhaust gas is where you get lag from. At low revs, not enough gas is coming through at a good enough speed to spool up the turbos.

Smaller turbos help as it takes less to spin them up, but then you get less abs.max. boost pressure.

Multiple turbos can also help depending on how they're configured (in series you could have a small one for initial boost and a big one for wallop), but I think they are "parallel" in a Maser - one turbo per cylinder bank.

If left to their own devices, the turbo would create more and more pressure as the revs rise. So something needs to be done to prevent things falling apart quick time. This is the function of the wastegate - that essential tool for tools in turbo'd Escorts etc. This whistling noise these make is the pressure being bled off away from the engine bay, thus maintaining sensible levels of boost.

Taking in hot gases to get them up to speed, then having a quick spinning metal blade and faster air at the other side generates a lot of heat. So the units themselves need plenty of cooling air or other means of cooiling.

And as I've been typing all this I've started to doubt what I'm saying

[murph7355]

www.turbo-kits.com/how_turbos_work3.html

I was off by a bit

I would still think that bonnet vents are for cooling

[mr_tony]

cheers and yup I'd agree on the cooling front too thinking about it... Still odd that the 4200 doesn't need the bonnet vents, perhaps being a slightly less stressed engine (390hp from 4.2L rather than 370 from 3.2L makes the difference perhaps...)

[exint2]

Turbos get very very hot - and hence need more cooling air!