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Car Forum / Alfa Romeo Cars / October 2004GT JTD Turbo lag?
OK, I'm not even sure if "turbo lag" is the correct terminology here, but it's my crude attempt to describe the feeling when you pull out at a roundabout in second gear, underestimate the approaching cars speed, grin sheepishly at the driver of the oncoming car who resolutely refuses to slow down and revels in your discomfort until (after what feels like an eternity) the GT hits 2000 rpm then BAM, you're off like a shot just in time to save your pride and bodywork! I don't know if it's because my 1.9 GT JTD is new (only 700 miles on the clock) and hasn't "loosened up" yet, but I'm (quite) sure that when I test drove the JTD, the turbo kicked in at around 1500 rpm which gave a much wider spread of power and usable acceleration at low revs. What is the experience of other JTD drivers on the group? Is it normal for the power to come on tap at 2000 rpm? Is there a "running in" period for the JTD? I've even heard it said that the engine management system automatically reduces the turbo until the engine has reached a predetermined mileage (which I doubt). Thanks - Grahame. > I don't know if it's because my 1.9 GT JTD is new (only 700 miles on the > clock) and hasn't "loosened up" yet, but I'm (quite) sure that when I test > drove the JTD, the turbo kicked in at around 1500 rpm which gave a much > wider spread of power and usable acceleration at low revs. My it shows how things have changed (makes me feel old). Expecting any sort of power at 1500rpm, especially in an Alfa renowned for its revvy engines seems way too optimistic. My recollection of turbo diesel hire cars (Mondeos etc.) is that just as the turbo kicks in and you get some power going the engine reaches its max revs and dies. I know things have moved on remarkably in the last few years, but I don't think I'd be relying on a car zipping along to nip in front of oncoming traffic being in a gear giving me just 1500 revs. Call me old fashioned... Grahame, don't worry, it's absolutely normal with the new 150bhps 1.9 JTD engine. I had a test drive in a GT like yours, and the only two problems are that at low revs there's no power (until 2000) and that's the engine is a bit too noisy from the inside. Yes, you have to do some more miles, and the engine will "tune up" a bit and became more comfortable to drive.  SignatureJacopo Prato, Italia -- Sportwagon 2.5 V6 24V Distinctive Join the Club! www.alfasport.net -- > Grahame, don't worry, it's absolutely normal with the new 150bhps 1.9 JTD > engine. I had a test drive in a GT like yours, and the only two problems > are that at low revs there's no power (until 2000) and that's the engine > is a bit too noisy from the inside. > Yes, you have to do some more miles, and the engine will "tune up" a bit > and became more comfortable to drive. Thanks Jacopo - Grahame. One simple solution: shift down a gear! SignatureCiao from Holland AlfistaGJ (Gert-Jan) Alfa red 156 SW 1.8 Madeno tuned (2000) (from 19 October: GT 2.0JTS) Golden Montreal 1428700 (1973/4) > OK, I'm not even sure if "turbo lag" is the correct terminology here, but > it's my crude attempt to describe the feeling when you pull out at a [quoted text clipped - 16 lines] > > Thanks - Grahame. >OK, I'm not even sure if "turbo lag" is the correct terminology here, but >it's my crude attempt to describe the feeling when you pull out at a [quoted text clipped - 3 lines] >the GT hits 2000 rpm then BAM, you're off like a shot just in time to save >your pride and bodywork! Sounds like you're new to a performance oil burner but it's perfectly normal. If you can find a graph of torque vs revs you will find it goes near vertical at the lowest revs Alfa gives for the power band of your car. In my case it's 1800rpm but the effect is an amazing (and slightly scary) BANG when you do it on full throttle. >I don't know if it's because my 1.9 GT JTD is new (only 700 miles on the >clock) and hasn't "loosened up" yet, but I'm (quite) sure that when I test >drove the JTD, the turbo kicked in at around 1500 rpm which gave a much >wider spread of power and usable acceleration at low revs. Don't expect much change. My engine's been the same since day 1. No change in oil consumption (zero..my oil tin is rusting away now!) and no change in performance. What will happen to make this 'problem' go away is you will learn to automatically dip the clutch to let the engine spin just into the power band so you don't drift down into the dead zone. Don't worry about it! >What is the experience of other JTD drivers on the group? Is it normal for >the power to come on tap at 2000 rpm? Is there a "running in" period for the >JTD? I've even heard it said that the engine management system automatically >reduces the turbo until the engine has reached a predetermined mileage >(which I doubt). IMHO, the only running in that's worthwhile on any new car is bedding in the piston rings by ragging the car rotten for it's first 20 miles!! For the rest of her life after that, warm her up fully and fairly gently every time then, drive as you want/can! SignatureZ Scotland Alfa Romeo 156 2.4JTD Veloce Leather 'Oil' be seeing you.. (Email without 'Alfa' in subject are auto-deleted..sorry!) <snip> > IMHO, the only running in that's worthwhile on any new car is bedding > in the piston rings by ragging the car rotten for it's first 20 > miles!! I've heard of this before. I assume you wait for the engine to warm up before ragging it? (Not that it matters, I can't see myself owning a new car for quite some time.) > For the rest of her life after that, warm her up fully and > fairly gently every time then, drive as you want/can! ><snip> >> IMHO, the only running in that's worthwhile on any new car is bedding [quoted text clipped - 4 lines] >before ragging it? (Not that it matters, I can't see myself owning a new car >for quite some time.) Waiting to warm the car up might stop this little trick working. In this *special* case you want to deliberately wear your rings and the cylinder honing pattern properly and you only have a VERY short time in which to do it. Once the honing pattern has gone..it's gone! How much engine running has a car done before you get it? It might be too late even by then. That honing pattern isn't designed to last very long at all. I should have mentioned previously that this technique *is* controversial and YMMV. SignatureZ Scotland Alfa Romeo 156 2.4JTD Veloce Leather 'Oil' be seeing you.. (Email without 'Alfa' in subject are auto-deleted..sorry!) May be a bit late (was on holidays) Being an "old" engine overhaul shop manager: You should imagine the honing pattern as a lot of x-stripped ridges of metal resulting from the fine machining which is only a very few microns deep. When you are too careful in the beginning, the high ridges will only be bent over to fill the "valleys" by the "rubbing" of the pistoon rings along the cylinder surface. In this way a very thing layer of metal (better "tin" as in a tin can) will be on your cylinder surface which will be very very smooth and do the exact opposite of what you intend; the oil will be pumping out. And over time, this layer will brake out and cause deep(er) scratches in the cylinder surface. Doing it the "rough" way with cold engine, the honing pattern will be forcefully "corrected" to a natural run in surface which is what you like to have. But, in fact it is wear as well which you don't want if you seek longlivety!! Therefor this way of "cold" running in should be limited to the first few driving minutes during i.e. the first 2500km's. Then change your oil AND filter (you must get rid of that awfull metal!!!) and change to the more sensible practice of carefully warming up your engine first and give the engine a beating only when warm. SignatureCiao from Holland AlfistaGJ (Gert-Jan) Alfa red 156 SW 1.8 Madeno tuned (2000) (soon: GT 2.0JTS) Golden Montreal 1428700 (1973/4) >><snip> >>> IMHO, the only running in that's worthwhile on any new car is bedding [quoted text clipped - 17 lines] > I should have mentioned previously that this technique *is* > controversial and YMMV. > Sounds like you're new to a performance oil burner but it's perfectly > normal. If you can find a graph of torque vs revs you will find it > goes near vertical at the lowest revs Alfa gives for the power band of > your car. In my case it's 1800rpm but the effect is an amazing (and > slightly scary) BANG when you do it on full throttle. Yes you're right, this is my first performance diesel (diesel of any kind for that matter). >>I don't know if it's because my 1.9 GT JTD is new (only 700 miles on the >>clock) and hasn't "loosened up" yet, but I'm (quite) sure that when I test [quoted text clipped - 9 lines] > power band so you don't drift down into the dead zone. Don't worry > about it! Funny you should say that, I'm already starting to get into that habit! I guess it just takes a little time to learn how best to extract the best performance from the JTD. It's suprising how different the technique is from driving a petrol engine (great fun though). >>What is the experience of other JTD drivers on the group? Is it normal for >>the power to come on tap at 2000 rpm? Is there a "running in" period for [quoted text clipped - 8 lines] > miles!! For the rest of her life after that, warm her up fully and > fairly gently every time then, drive as you want/can! Well, I took it easy for the first 1000 miles or so, but the gloves are off now :) Thanks for taking the time to respond (and for putting my mind at rest!) - Grahame. <Snip> >Well, I took it easy for the first 1000 miles or so I subscribe to the no-running-in school of thought that says 'from day one drive the car gently until warm and, after that, drive it how you like'. Apart from anything else, it's just too tempting to have fun in Alfas (a top make for getting a speeding fine in BTW!). Drive an Alfa 'easy' for 1000 miles - you've got the patience of a saint! SignatureZ Scotland Alfa Romeo 156 2.4JTD Veloce Leather 'Oil' be seeing you.. (Email without 'Alfa' in subject are auto-deleted..sorry!) |
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