nissan navara d22 2.5 turbo lag?
Submitted: Tuesday, Dec 30, 2008 at 22:38
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maddog-george
hi all,
i got a nissan navara d22 2.5 turbo diesel ute, the new ones on the market, and i was told as they have a variable turbo they should not experience any lag at all.
thing is, when i'm at a red light and it turns green, i'll drive off slowly, and if i floor it it'll slowly get faster to say 1200RPM (just top of my head) and then it'll just take off like nuts.
is that turbo lag? if not is that normal?
i also heard with EFI engines that when you want to floor it, it takes a few seconds to build up speed then takes off. true or not?
i aint too much of a engine person and i'm new at the whole turbo game.
cheers,
george
Reply By: DCTriton - Wednesday, Dec 31, 2008 at 00:59
Wednesday, Dec 31, 2008 at 00:59
Lag is the time it takes the turbo to spool up, governed by how efficiently the exhaust gases interact with the internal vanes...
Variable geometry turbo's give great ganes in this area as they allow the turbo to spool relatively quickly but don't choke the engine at higher rpm...
Variable geometry by no means equates to NO lag, it only means reduced lag and if your 1200rpm (off the top of your head) is correct, I'd say you're doing extremely
well...
AnswerID:
341914
Reply By: maddog-george - Wednesday, Dec 31, 2008 at 03:40
Wednesday, Dec 31, 2008 at 03:40
ahh, ok. so basically because it's a diesel engine it just works up speed slowly then gets going fast.
cheers for the info by the way.
on another note, though this may sound silly, i have seen videos where the turbo makes a fluttering noise when the gas is let off after revving it.
would the standard turbo be able to do that? guessing not as it is fairly small
AnswerID:
341916
Follow Up By: Malleerv - Wednesday, Dec 31, 2008 at 07:18
Wednesday, Dec 31, 2008 at 07:18
I am guessing your talking about the noise a blow off valve makes on boy racer cars. Most speed shops sell them but they are mainly for petrol engines where the intake has a butterfly throttle body. When the throttle is released back to idle from high rpm any excess air pressure is released by the blow off valve giving you a semi high pitch fluttering noise. I cant see it working on a diesel as they have a full flow intake system which means they are just getting as much air into the engine as possible all the time.
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Follow Up By: maddog-george - Wednesday, Dec 31, 2008 at 14:08
Wednesday, Dec 31, 2008 at 14:08
nah mate, its not a blow off valve. thats to do with excess pressure release.
"The flutter is caused when the throttle is shut and air caught betweent the free-spinning turbo and the closed throttle (when you have no vent ie blow-off valve).
The consequent back pressure forces the air back through the turbine blades. The more technical term for this is 'cavitation' "
go on youtube and have a look for yourself, its totally different to a ricer car pffffffffffffffffffttt blow off valve noise, haha. its more like, too to to to tooo, lol
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Reply By: 93 Navara - Wednesday, Dec 31, 2008 at 09:28
Wednesday, Dec 31, 2008 at 09:28
Slightly off topic to your original question maddog, but does anyone know the differrence between the 2.5 in the D22 and D40?. Its output is considerble less, is that simply a computer upgrade to rectify? An exhaust and a D40 chip might assist you maddog.
Ben
AnswerID:
341923