diesel turbo
Turbo Mini Forums

hi all, im gonna look really stupid now but oh well, here goes,

What is the differnce between a diesel turbocharger and a petrol one ? if any, could a diesel one be used on a petrol engine ?

cheers all Dave

Dave Fletcher A.M.I.M.I

i have no idea mate, all i could find online was this ..... Turbo charging a diesel is easier than turbo charging a petrol engine. One problem for a petrol engine is that if the compression ratio is too high, and the pressure in the cylinder gets too high during the inlet stroke, then the fuel/air mixture can start to burn too soon, while the piston is still on the way up. A turbo increases the pressure in the cylinder making this problem worse. With a diesel engine, there is no fuel in the cylinder during the compression stroke, so a turbo can be used to pack as much air in there as desired without causing problems.

which seems slightly irrelevant but might help somehow.
Dont diesel engines rev a lot lower than petrol engines? Maybe the turbines are a different shape to help them spool up better at low revs?

NO LONGER A <3 lover of BOLT-ON plastic <3 .... (and DOUBLE proud of it)

They are differnt... not just in sizing, as boyracer says due to being lower reving. A diesel has no throttle so always runs at 100% of its VE effeciency.

The main differece is in the tempretures thou, diesel exhaust gas temps are much much lower than petrol.

Alex

AlexF

so does that mean that you couldnt use a diesel turbocharger on a petrol engine? I cant see that the temperature differnece is that much overall is it?

The turbo on the boat i use (used to be bmw petrol, now perkins td!) is often glowing cherry red, and i know that my mates 5 turbo use to glow all the time? surely they cant get much hotter, or am i missing the point?

Pete

And on the 7th day........... God created turbochargers!

I was told that the T15 from a vauxhall td was good for 100bhp a series that was really nice to drive, i.e. not alot of lag etc.

I've never seen a diesel turbo glow red i must be honest!!! But if it's a marine application, it's probably got a big restriction in the exhaust (after the turbine wheel) which could make it run very hot...

As Alex says, diesels do 'normally' have a lower exhaust gas temperature, hence why you hardly ever find a watercooled centre housing on a 'mass production' diesel turbocharger unit.

ive got a picture somewhere, we were going rather quickly tho its not supposed to be running red hot! also its not a marine engine, (well it is, its in a boat, even been under water once, but thats another story) its out of a montego! 2l td with pump wound up a little bit. runs a standard downpipe to big exhaust! changed it so we could run red diesel at 22p rather than unleaded at 79p!

so is the factor that its not water cooled. i only ask, because ive been looking at building a t2 from a montego, (v cheap) into a 5gtt core that i have aquaired. i know it will fit, but will it be any good? i assume that the materials used in the manufactur are the same in terms of compressor wheels etc?

And on the 7th day........... God created turbochargers!

You can make diesels glow red hot but thats not hard 550 degrees c will do that, but you seriously have to push a diesel to do that, 300 odd is more then tempreture. This is why they have dificulties with new technologies such as NOx traps and diesel particulate filters.

Petrols on the other hand can see as much as 800 degrees on older stuff like our engines and up 1000 degrees C on new stuff that runs lean, think VW 1.8.

Watercooling is mainly for turbo life on shut down, the core is less hot so less damaged by hot shut down. Remeber to let your turbos spin down and idle chaps!! Water cooling stops the oil burning in the bearings and shaft AKA "black death".

Whats wrong with the montego core?

Alex

Alex

AlexF

nothings wrong with the montego core afaik - just thought it would be better to have it water cooled?

Pete

And on the 7th day........... God created turbochargers!

only if you want it to last longer then the engine, and are going to be careless at shut down :)

Alex

AlexF

to be fair, i cant actually see the engine lasting that long before it blows a headgasket. why? well its got two at the moment, to help reduce compression. really must get a copper one made up.......

And on the 7th day........... God created turbochargers!

it helps reduce CR but promotes det anyway... so your on to a bit of a losser!

I'd just go with the non-water cooled core and be done with it!

Alex

AlexF

Fair enough, i think i best finish the T2 adapter plate, and give it a go....

And on the 7th day........... God created turbochargers!