3.9 vs 4.0 V8 reliability? which is better?

[juha_teuvonnen]

Then why do they still use bolts instead of studs in their all aluminum engines? they have much higher stresses than most of the rover V8s will ever see.

Because bolts are cheaper than studs and they build throwaway engines that are not meant to be ever repaired. Or may be because they operate based on a misguided belief that their engineering is so good that their designs will outlast the car? Or may be they don't care what happens once the warranty expires, in fact they don't mind making a couple of bucks by selling a set of bolts?

GM used the distributor driven oil pump up through the gen VI big block. If it was a flawed design, why would they have kept it for over 40years? (PS, those engines are still in production today.) GM put enormous amounts of money into designing the oiling system on the big block and the oil pump wasn't a weak point on it.

The new V8s they make use the crank driven pumps. Would they put one in their most powerful production engine (LS9) if it was a crappy design and didn't make enough pressure?

And how often do you have problems with the oil pump losing its prime anyway?

Big blocks make a lot of power due to sheer displacement, hence no need to have a highly tuned engine. Consequently you can get away with a 40 year old design. Distributor driven pumps are bad, at least in the Rover case, which is why they were replaced with the new design.

 

[mbrummal]

Because bolts are cheaper than studs and they build throwaway engines that are not meant to be ever repaired. Or may be because they operate based on a misguided belief that their engineering is so good that their designs will outlast the car? Or may be they don't care what happens once the warranty expires, in fact they don't mind making a couple of bucks by selling a set of bolts?

What BMW engine is made to be thrown away? When was the last time you saw a rover engine go 300k miles with nothing but oil changes? I have seen an M52 engine do it. It was easy to work on as well. They use bolts (torque to yield) because they maintain their tension much more consistently than studs which have to be re-torqued after a short period. That just isn't practical on modern cars.

Big blocks make a lot of power due to sheer displacement, hence no need to have a highly tuned engine. Consequently you can get away with a 40 year old design. Distributor driven pumps are bad, at least in the Rover case, which is why they were replaced with the new design.

While it is true there is no replacement for displacement, what does the level of tune have to do with the oiling requirements? Many of high performance big blocks (600-700 naturally aspirated horse power) still use the stock oil pump. It is completely adequate. The raeson GM went to the gerotor oil pump (as I understand it) was because it is more efficient and allows for a shorter oil pan, not because the gear pump is inadequate.

 

[juha_teuvonnen]

What BMW engine is made to be thrown away? When was the last time you saw a rover engine go 300k miles with nothing but oil changes? I have seen an M52 engine do it.

A sample of one is statistically insignificant. Modern BMW (and Porsche) engines are often designed in such a way that rebuilding them is not practical. Euro versions of M52 have nikasil coated cylinders. US versions have cast iron sleeves - BMW learned the hard way (M60 debacle) that nikasil and high-sulfur fuels do not mix. There were quite a few unhappy BMW customers in the UK with the broken M52 motors back in the day - their fuel standards were just as lousy as ours. Resleeving a nikasil motor is almost never practical. Resleeving an M52 is not likely to be practical on a well worn BMW.

So, speaking specifically about M52, if you are lucky then you throw it away at 300K (presumably with the car), if you are not - at 150K or may be even 60K. This engineering is good for BMW AG and bad for the buyer.

It was easy to work on as well. They use bolts (torque to yield) because they maintain their tension much more consistently than studs which have to be re-torqued after a short period. That just isn't practical on modern cars.

The wonderful consistency of TTY bolts IMHO is overly exaggerated. I have had much better luck with quality studs than TTY bolts. The clampdown forces that can be safely achieved with studs are greater than those with TTY bolts and you the risk of pulling threads and damaging block is much lower. Steel thread going into aluminum block is not something that you want to stress a lot (wonderful properties of aluminum). I would never build a turbocharged or supercharged GM LSx engine with forced induction without studs. I have seen many a head gasket failure with TTY bolts. I have not seen nearly as many with head studs, assuming proper installation. YMMV.

TTY bolts are another feature of 'throwaway' motors - once you take the heads of a couple of times you may end up with a few helicoils in the block, which is not a good thing. Ideally the heads get torqued once in alifetime of the engine, at the factory. Another such 'feature' are powdered metallurgy fracture-split con rods. Once they stretch (and they will) - throw them away.

While it is true there is no replacement for displacement, what does the level of tune have to do with the oiling requirements? Many of high performance big blocks (600-700 naturally aspirated horse power) still use the stock oil pump. It is completely adequate. The raeson GM went to the gerotor oil pump (as I understand it) was because it is more efficient and allows for a shorter oil pan, not because the gear pump is inadequate.

The higher level of tune means that your engine runs leaner and consequently hotter. This means that you better have enough oil pump to pump it through oil cooler before it reaches the temperature when it starts to carbonize. It also means that forces that try to squeeze out the oil film on various surfaces (for example crank bearings) are stronger. Higher oil pressure helps combat these forces. Consequently, if the engine is highly tuned, it is prudent to have adequate oil pump

 

[mbrummal]

A sample of one is statistically insignificant. Modern BMW (and Porsche) engines are often designed in such a way that rebuilding them is not practical. Euro versions of M52 have nikasil coated cylinders. US versions have cast iron sleeves - BMW learned the hard way (M60 debacle) that nikasil and high-sulfur fuels do not mix. There were quite a few unhappy BMW customers in the UK with the broken M52 motors back in the day - their fuel standards were just as lousy as ours. Resleeving a nikasil motor is almost never practical. Resleeving an M52 is not likely to be practical on a well worn BMW.

So, speaking specifically about M52, if you are lucky then you throw it away at 300K (presumably with the car), if you are not - at 150K or may be even 60K. This engineering is good for BMW AG and bad for the buyer.


The wonderful consistency of TTY bolts IMHO is overly exaggerated. I have had much better luck with quality studs than TTY bolts. The clampdown forces that can be safely achieved with studs are greater than those with TTY bolts and you the risk of pulling threads and damaging block is much lower. Steel thread going into aluminum block is not something that you want to stress a lot (wonderful properties of aluminum). I would never build a turbocharged or supercharged GM LSx engine with forced induction without studs. I have seen many a head gasket failure with TTY bolts. I have not seen nearly as many with head studs, assuming proper installation. YMMV.

TTY bolts are another feature of 'throwaway' motors - once you take the heads of a couple of times you may end up with a few helicoils in the block, which is not a good thing. Ideally the heads get torqued once in alifetime of the engine, at the factory. Another such 'feature' are powdered metallurgy fracture-split con rods. Once they stretch (and they will) - throw them away.



The higher level of tune means that your engine runs leaner and consequently hotter. This means that you better have enough oil pump to pump it through oil cooler before it reaches the temperature when it starts to carbonize. It also means that forces that try to squeeze out the oil film on various surfaces (for example crank bearings) are stronger. Higher oil pressure helps combat these forces. Consequently, if the engine is highly tuned, it is prudent to have adequate oil pump

hmm. so power is produced by running lean. I did not know that. Hotter, yes, but not because of a lean condition. It runs hotter because more fuel is being burned. The thing that really affects the bearings is their clearances. If there are excessive clearances in any engine, the stock oil pump will struggle to keep up. If you have tight clearances, the factory oil pump can keep up to massive amounts of power. true, there are bigger forces trying to squeeze the oil from between the the bearing surfaces but that is why the oil is pressurized- to keep new oil going in where the old is squeezed out. Higher pressures don't necessarily mean more protection. if oil flow is adequate, you won't have problems. If you add a bigger pump, you are only wasting more power turning a bigger pump.

If the engine is worn out and has excessive clearances, the stock oil pump can be inadequate but what caused the wear in the first place? it wasn't the oil pump's fault.

 

[juha_teuvonnen]

hmm. so power is produced by running lean. I did not know that. Hotter, yes, but not because of a lean condition. It runs hotter because more fuel is being burned.

I think you are mistaken here. In most modern internal combustion engines the maximum HP/torque is somewhere leaner than the stoichiometric AFR of 14.7. If you go too far on the lean side you start to loose power. The other unpleasant side effects of running lean are detonation and heat. The more modern engines tend to run leaner and hotter which allows them to produce more HP and torque out of the same displacement. You have to use better materials and stronger components and better cooling system (compare LT1 to small block 350 - a good example). Th other unfortunate side effect of running lean is lots and lots of NOx emissions. Which is why most street-legal engines are essentially "detuned" to meet the emissions standards. When you go on the reach side of the AFR you end up with little to no NOx but CO and HC start to climb. Also your HP and torque starts going down. The leaner calibrations are considered more aggressive and the reacher calibrations are considered more conservative. When you tune an engine you typically start with a conservative, rich calibration and start working your way over to the lean, "aggressive" side gaining horsepower on your way. You keep monitoring the emissions and detonation (pinging). If the engine starts pinging - you have gone too far. It does not take long to destroy a pinging engine while tuning it on a dyno - don't ask me how I know The optimal point in in a different spot for different engines, it varies quite a bit depending on how well it flows air, camshaft profile, etc.

IMHO one of the reasons why 4.0 GEMS motors fail more frequently is because they have a leaner and hotter "more aggressive" calibration to meet the emissions requirements. Not too lean to start making lots of NOx, but enough not to make tons of CO and HC. Unfortunately this calibration has proved itself to be too aggressive for the old Buick motor.

There is a great book by Sir Harry R. Ricardo called "The high-speed internal combustion engine", it explains everything extremely well. I consider it a timeless classic and highly recommend it.

The thing that really affects the bearings is their clearances. If there are excessive clearances in any engine, the stock oil pump will struggle to keep up. If you have tight clearances, the factory oil pump can keep up to massive amounts of power. true, there are bigger forces trying to squeeze the oil from between the the bearing surfaces but that is why the oil is pressurized- to keep new oil going in where the old is squeezed out. Higher pressures don't necessarily mean more protection. if oil flow is adequate, you won't have problems. If you add a bigger pump, you are only wasting more power turning a bigger pump.

If the engine is worn out and has excessive clearances, the stock oil pump can be inadequate but what caused the wear in the first place? it wasn't the oil pump's fault.

All of the above deals with tight clearances, which applies to modern engines. The Rover engine is a hotrodded version of a 1955 Buick motor, so you better have an adequate oil pump. Actually, you would be better off with "more than adequate" because the stock Rover engine is built using poor quality materials that wear out quickly and open up the tolerances. Which is why distributor-driven pump was revised and then replaced with a gerotor pump. Yes, in a more modern engine, built from quality parts you can get away with smaller oil pump. It's just not the case with the ancient Land Rover engine. Also, the mechanical losses by having a bigger oil pump are minimal, but the gains in reliability are huge. Way worth it for most high-volume manufacturers. Compared to the likes of GM and Toyota, Land Rover makes "two and a half" vehicles a year. Which makes them a lot more willing to take engineering risks, just like Porsche. IMHO this is a bad strategy that combined with many other mistakes by LR led to scores of disgruntled customers and failure of LR as a business.

 

[p m]

IMHO one of the reasons why 4.0 GEMS motors fail more frequently is because they have a leaner and hotter "more aggressive" calibration to meet the emissions requirements. Not too lean to start making lots of NOx, but enough not to make tons of CO and HC. Unfortunately this calibration has proved itself to be too aggressive for the old Buick motor.

Your general reasoning is correct, with some possible exception.

There was a great write-up by one of the ECU chip upgrade manufacturers in some old Discoweb thread explaining the peculiarities of Rover fuel and ignition map. One fact was rather unexpected to me - that is, at some stage of GEMS design, engineers realised that they could not reliably determine the onset of detonation, and decided to be on the safe side by making the mixture richer.

Also, from my personal experience, and from observing the DW threads since its inception, I see no tendency of 4.0 GEMS motors to fail more frequently than earlier Lucas 14CUX or later Bosch EFI. Rather, 4.0 GEMS seems to be the most reliable engine in pre-L322 Rovers.

 

[ptschram]

Your general reasoning is correct, with some possible exception.

There was a great write-up by one of the ECU chip upgrade manufacturers in some old Discoweb thread explaining the peculiarities of Rover fuel and ignition map. One fact was rather unexpected to me - that is, at some stage of GEMS design, engineers realised that they could not reliably determine the onset of detonation, and decided to be on the safe side by making the mixture richer.

Also, from my personal experience, and from observing the DW threads since its inception, I see no tendency of 4.0 GEMS motors to fail more frequently than earlier Lucas 14CUX or later Bosch EFI. Rather, 4.0 GEMS seems to be the most reliable engine in pre-L322 Rovers.

Both Chris Crane and John Roison have discussed the issues of fuel map error-induced localized overheating causing liner movement. John thinks it's more prevalent on the 4.6s as they produce more power and the transmission doesn't downshift as often, nor when sometimes needed.

As for the 4.0 GEMS vs the rest, the DII engines are beginning to frighten me. I have (oh geez) five of them in the shop right now and I'm worried that three of them need engines. Worse yet, all five might end up needing engines.

 

[robertf]

You keep monitoring the emissions and detonation (pinging). If the engine starts pinging - you have gone too far. It does not take long to destroy a pinging engine while tuning it on a dyno - don't ask me how I know

I'll bite.... how do you know?

 

[mbrummal]

I think you are mistaken here. In most modern internal combustion engines the maximum HP/torque is somewhere leaner than the stoichiometric AFR of 14.7. If you go too far on the lean side you start to loose power. The other unpleasant side effects of running lean are detonation and heat. The more modern engines tend to run leaner and hotter which allows them to produce more HP and torque out of the same displacement. You have to use better materials and stronger components and better cooling system (compare LT1 to small block 350 - a good example). Th other unfortunate side effect of running lean is lots and lots of NOx emissions. Which is why most street-legal engines are essentially "detuned" to meet the emissions standards. When you go on the reach side of the AFR you end up with little to no NOx but CO and HC start to climb. Also your HP and torque starts going down. The leaner calibrations are considered more aggressive and the reacher calibrations are considered more conservative. When you tune an engine you typically start with a conservative, rich calibration and start working your way over to the lean, "aggressive" side gaining horsepower on your way. You keep monitoring the emissions and detonation (pinging). If the engine starts pinging - you have gone too far. It does not take long to destroy a pinging engine while tuning it on a dyno - don't ask me how I know The optimal point in in a different spot for different engines, it varies quite a bit depending on how well it flows air, camshaft profile, etc.

IMHO one of the reasons why 4.0 GEMS motors fail more frequently is because they have a leaner and hotter "more aggressive" calibration to meet the emissions requirements. Not too lean to start making lots of NOx, but enough not to make tons of CO and HC. Unfortunately this calibration has proved itself to be too aggressive for the old Buick motor.

There is a great book by Sir Harry R. Ricardo called "The high-speed internal combustion engine", it explains everything extremely well. I consider it a timeless classic and highly recommend it.

Why is this engine running slightly rich at max power?
http://www.ngmhouseofpower.com/ngmimages/mini-Stage IV versus Stock Manifold.bmp

and this one:
http://www.ls1tech.com/forums/attac...239225880-tuning-jesse-bubb-jerry-dyno-af.jpg

Yes, detonation is a problem when making power but it is mostly caused by not being able to deliver the necessary fuel, a lean condition results and bad things happen. When tuning, you start out excessively rich and make it up to slightly rich. after going a little past that, the power starts to drop off, so it is put back to the level with the most power: rich rather than lean.

All of the above deals with tight clearances, which applies to modern engines. The Rover engine is a hotrodded version of a 1955 Buick motor, so you better have an adequate oil pump. Actually, you would be better off with "more than adequate" because the stock Rover engine is built using poor quality materials that wear out quickly and open up the tolerances. Which is why distributor-driven pump was revised and then replaced with a gerotor pump. Yes, in a more modern engine, built from quality parts you can get away with smaller oil pump. It's just not the case with the ancient Land Rover engine. Also, the mechanical losses by having a bigger oil pump are minimal, but the gains in reliability are huge. Way worth it for most high-volume manufacturers. Compared to the likes of GM and Toyota, Land Rover makes "two and a half" vehicles a year. Which makes them a lot more willing to take engineering risks, just like Porsche. IMHO this is a bad strategy that combined with many other mistakes by LR led to scores of disgruntled customers and failure of LR as a business.

I thought you were referring more to the general design, not land rover's specifically. I still don't think the engine is made from inferior materials. The only part that wears is the bearing surfaces which have almost nothing to do with the rest of the engine's construction and as PT will tell you, the camshaft doesn't have much wear for the most part. If the oil pump has adequate flow and the engine isn't flogged when its cold, there should be relatively little wear. The problems arize when sludge buildup in the heads prevent oil drain back or sludge in the oil pan starve the oil pump. Then, wear occurs, bearing clearances are enlarged and the stock pump becomes inadequate.

 

[gardrover]

rpi has a good pic of the problem

http://www.v8engines.com/ebaypictures/engines/2006_block_casting.jpg

new Coscast block;
http://cgi.ebay.co.uk/Cos-cast-V8-E...temQQimsxq20091228?IMSfp=TL091228162001r31762

some good pics on their listing/ overview of differences.

regarding the sludge, i'll be dropping my pan at some point soon to re-seal it (valve covers too), truck has 190k and has been running rotella for over 100k of those, interested to see any sludge action

im sure my cam and dizzy are worn to poop but the mileage is still ~14/15

trip computer on a L322 i drove the other day was registering 8.9 mpg.

i want to put my e300D in the disco...........

 

[Tugela]

trip computer on a L322 i drove the other day was registering 8.9 mpg.

That is surprising. Then again, the L322 weighs more than anything fitted with a 3.9/4.0. But does it really weigh THAT much more?

 

[LuisC]

Has anyone ever thought to ask the question? Why did Buick get rid of the aluminum V8?
Another question. Why did GM try to buy the design back a few years ago?

Sorry. I just came into this thread. Nothing better to do. I've seen it and kept passing on it. Just was not concerned to much since I'm a dieselhead.
But I will say I did like my 4.0 GEMS. It had ported and polished heads and ran like a champ. Didn't do to bad against a stock 4.6.

 

[gardrover]

Has anyone ever thought to ask the question? Why did Buick get rid of the aluminum V8?
Another question. Why did GM try to buy the design back a few years ago?

Sorry. I just came into this thread. Nothing better to do. I've seen it and kept passing on it. Just was not concerned to much since I'm a dieselhead.
But I will say I did like my 4.0 GEMS. It had ported and polished heads and ran like a champ. Didn't do to bad against a stock 4.6.

how is your r380 holding up under the torque of the 2.8?

 

[p m]

Has anyone ever thought to ask the question? Why did Buick get rid of the aluminum V8?
Another question. Why did GM try to buy the design back a few years ago?

Relatively easy, not sure how true:
1) because GM learned how to do thin-walled iron castings, and had no need for aluminum.
2) because GM learned that they needed to make things lighter to improve fuel economy, and 150-200 lbs of savings on all-aluminum vs. cast iron engine are substantial.

 

[juha_teuvonnen]

I'll bite.... how do you know?

Blew up an engine while tuning it on a dyno. It was an expensive lesson to learn.

 

[juha_teuvonnen]

Why is this engine running slightly rich at max power?
http://www.ngmhouseofpower.com/ngmimages/mini-Stage%20IV%20versus%20Stock%20Manifold.bmp

and this one:
http://www.ls1tech.com/forums/attachments/cadillac-cts-v-2004-2009/174638d1239225880-tuning-jesse-bubb-jerry-dyno-af.jpg

I can't tell you why. Every engine is different and there are too many variables in the mix, such as volumetric efficiency, valve overlap, exhaust backpressure, cooling, etc. Besides, engines are tuned not just for absolute HP numbers but also for driveability, and sometimes even for fuel economy, emissions and durability. Every tune is a compromise and a complex optimization problem. Slightly rich calibration often makes for the most drivable car, but not for the most efficient in terms of absolute HP and torque.

I thought you were referring more to the general design, not land rover's specifically. I still don't think the engine is made from inferior materials.

Too bad the parts of my 138K mile engine are already at the metal recycling place. Pretty much crapola all the way, crom crank to cam including heads.

The only part that wears is the bearing surfaces which have almost nothing to do with the rest of the engine's construction and as PT will tell you, the camshaft doesn't have much wear for the most part. If the oil pump has adequate flow and the engine isn't flogged when its cold, there should be relatively little wear.

It is uncommon to flog a cold 4.0L V8 automatic in California. Nevertheless there are plenty of failed engines and Land Rovers that need an engine around here.

The problems arize when sludge buildup in the heads prevent oil drain back or sludge in the oil pan starve the oil pump. Then, wear occurs, bearing clearances are enlarged and the stock pump becomes inadequate.

Sludge buildup is a sign of either poorly designed oiling system or a poor quality oil. There are plenty of failed LR engines around. I bet not all owners abused the heck out of them and used crappy oil, especially since the car is expensive.

 

[juha_teuvonnen]

Has anyone ever thought to ask the question? Why did Buick get rid of the aluminum V8?
Another question. Why did GM try to buy the design back a few years ago?

I am not sure I buy that story. GM has had an excellent LSx (LS1/LS6/LS2/LS3/LS7) family of engines since at least 1997. They probably still have the rights to the Olds variant of the aluminum V8.

If GM needed an aluminum V8 quickly and on a budget, they would simply make an aluminum variant of LT1 or a chevy 350. Either option would be much more cost-effective for them than producing the LR motor. They choose to redesign the v8 from scratch and the result was LS1. IMHO the LSx series engine is what the LR should be powered with.

 

[LuisC]

how is your r380 holding up under the torque of the 2.8?

It seems to be holding up OK. But I don't strain the R380 with a full throttle in 4th or 5th gear.
Right now, though, it is parked doing some additional work on the Rover.

 

[robertf]

I am not sure I buy that story. GM has had an excellent LSx (LS1/LS6/LS2/LS3/LS7) family of engines since at least 1997. They probably still have the rights to the Olds variant of the aluminum V8.

If GM needed an aluminum V8 quickly and on a budget, they would simply make an aluminum variant of LT1 or a chevy 350. Either option would be much more cost-effective for them than producing the LR motor. They choose to redesign the v8 from scratch and the result was LS1. IMHO the LSx series engine is what the LR should be powered with.

if it was that simple GM would have done that in the 60's instead of building the 215 engine.


what engine did you blow up on the dyno? what ems and who was doing the tuning?

 

[juha_teuvonnen]

if it was that simple GM would have done that in the 60's instead of building the 215 engine.


what engine did you blow up on the dyno? what ems and who was doing the tuning?

Porsche 944 turbo. I have built the engine, and I was doing the tuning. The EMS was a custom/prototype unit. I am fully responsible for killing that particular engine.