[ANSWERED] Changes to Engine Oil Cooling
08-10-2015, 02:23 PM
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[ANSWERED] Changes to Engine Oil Cooling
Original question is here.
grcor asked:
For many years GM has used radiators with an engine oil cooler inside left tank for trucks, SUVs, and in the Corvette 2005-2007 Z51s. This method of cooling engine oil works well and has the added benefit of warming the engine oil during warm up. It also keeps engine room congestion and the number of pluming connections to a minimum.
The 2006 – 2010 Z06s use a large air/oil cooler mounted in front of the radiator. This method of oil cooling works well at the track, but in normal street driving it keeps the oil too cold. On a 50 to 60 degree day, it is common to see oil temperatures in the 120 to 140 range (DIC). The DIC is reading oil temperature from the bottom of the external reservoir, the oil first travels to the oil pump, then thru to the oil filter then thru to the oil cooler before it enters the engine. So the temperature of the oil entering the engine is even colder than what the DIC says. What is the optimum oil temperature for a LS7?
The 2011-2013 Z06s, 2009-2013 ZR1s, and C7 Z51s/Z06s use a coolant/oil cooler assembly to cool/warm engine oil. This method needs to have a coolant line plumbed from the block to the cooler assembly and from the cooler assembly to the radiator. The cooler assembly and extra plumbing would seem to add to engine room congestion and increased potential of coolant leaks as time goes on.
The current Camaro Z28 uses a bigger coolant/oil cooler assembly than the Corvettes.
Can you please tell us the advantages and disadvantages of each oil cooling approach from an engineering point of view and why you changed the oil cooling approach so many times?
For many years GM has used radiators with an engine oil cooler inside left tank for trucks, SUVs, and in the Corvette 2005-2007 Z51s. This method of cooling engine oil works well and has the added benefit of warming the engine oil during warm up. It also keeps engine room congestion and the number of pluming connections to a minimum.
The 2006 – 2010 Z06s use a large air/oil cooler mounted in front of the radiator. This method of oil cooling works well at the track, but in normal street driving it keeps the oil too cold. On a 50 to 60 degree day, it is common to see oil temperatures in the 120 to 140 range (DIC). The DIC is reading oil temperature from the bottom of the external reservoir, the oil first travels to the oil pump, then thru to the oil filter then thru to the oil cooler before it enters the engine. So the temperature of the oil entering the engine is even colder than what the DIC says. What is the optimum oil temperature for a LS7?
The 2011-2013 Z06s, 2009-2013 ZR1s, and C7 Z51s/Z06s use a coolant/oil cooler assembly to cool/warm engine oil. This method needs to have a coolant line plumbed from the block to the cooler assembly and from the cooler assembly to the radiator. The cooler assembly and extra plumbing would seem to add to engine room congestion and increased potential of coolant leaks as time goes on.
The current Camaro Z28 uses a bigger coolant/oil cooler assembly than the Corvettes.
Can you please tell us the advantages and disadvantages of each oil cooling approach from an engineering point of view and why you changed the oil cooling approach so many times?
Tadge answered:
To answer this question I consulted with Richard Quinn, our powertrain cooling development engineer who has a long history on Corvette cooling development:
In the early stages of designing a performance engine, we make allowances to divert a portion of the lube system oil flow for cooling. Engineers evaluate different ways to extract the heat energy required and select the best one for the application based on a number of factors. As you’ve pointed out, we’ve taken different approaches over the years on Corvette and each one had specific benefits for the powertrain and chassis at the time.
I mention the chassis as an important factor because throughout modern Corvette history and especially the last three generations, the performance envelope of the car has seen a steady, continuous increase. As cornering capability has improved, we’ve modified our lubrication and cooling strategy to match.
The earliest oil cooler you mention - the radiator end-tank style in the C6 Z51, removed 3.5kW of heat from the oil and deposited it into the main engine coolant system. The downsides of this method are the relatively small capacity limit and the oil-side restriction penalty. Moving any fraction of the oil from the engine to the radiator takes away from the main goal of the lubrication system which is first and foremost to supply the bottom end (main bearings) with good oil pressure. But in the Z51 package, the tradeoff was favorable and the cooling adequate for the operating envelope of the LS2 engine.
With the introduction of the C6 Z06 we had a chassis and tire package that allowed us to put much more power to the ground, compounded by an LS7 engine that loved to spin. Those elements drove us to add a much higher oil cooling capacity (roughly 16Kw) than an end-tank cooler could provide, so an air-to-oil cooler was selected as a ‘big hammer’ solution for the dry-sump motors, chosen for its ability to cool better at higher vehicle speeds. We made a conscious decision to go that route, as there are several downsides to air-to-oil coolers. They add airflow restriction, which reduces the effectiveness of the main radiator and impacts AC performance. There is unwanted oil-side restriction which takes some pressure potential from the main bearings. And as you mention, on cold days the oil will always be somewhat over-cooled. (Overcooling oil isn’t the worst thing, but it costs some fuel efficiency as colder oil has higher viscosity and more friction loss.) But for a car as track-oriented as the C6 Z06, this was the right trade-off to make, using a balanced take-off valve to bleed just enough oil to the cooler to satisfy cooling needs.
In the spirit of continuous improvement, in the 2009 ZR1 we increased oil cooler capacity further. We also needed to maintain higher main bearing oil pressure to support the huge horsepower increase of the LS9. That drove us to integrate the oil cooler as a liquid-liquid heat exchanger mounted as part of the engine assembly- a triple benefit, with more kW of heat rejection (almost 20Kw), reduced oil-side restriction, and elimination of the front-end airflow blockage of the previous air/oil cooler. This option also reduced the plumbing complexity, with only one small coolant circuit leaving the engine block to return to the main radiator coolant circuit. The downside is that the main radiator has to reject the heat extracted by this cooler, but the tradeoff is overall a net positive. We’ve been very happy with the integrated liquid-liquid oil cooler ever since we adopted it, as it has been a win-win over all of the previous alternatives in terms of capacity, restriction, and the ability to better regulate normal operating temperatures.
The Z/28 Camaro presented a unique challenge, with higher mass and gear ratios selected to carry very high RPM on track. It required a capacity increase in the liquid-liquid cooler system, and the team added a supplemental air/oil coolant radiator dedicated to providing colder water to the engine oil cooler. This had a double benefit of reducing bulk coolant temp and oil temp, but with a tradeoff consequence of added complexity and added mass.
As the Corvette chassis improves and continues to drive more lateral loads through the lubrication system, we are challenged to keep up with the increasing demand of racetrack use. We’ve gone from 3.5kW of oil cooling in the C6 Z51 to 21kW in today’s C7 Z06. You can be confident we’ll continue along this path as Corvette performance improvements dictate it.
To answer this question I consulted with Richard Quinn, our powertrain cooling development engineer who has a long history on Corvette cooling development:
In the early stages of designing a performance engine, we make allowances to divert a portion of the lube system oil flow for cooling. Engineers evaluate different ways to extract the heat energy required and select the best one for the application based on a number of factors. As you’ve pointed out, we’ve taken different approaches over the years on Corvette and each one had specific benefits for the powertrain and chassis at the time.
I mention the chassis as an important factor because throughout modern Corvette history and especially the last three generations, the performance envelope of the car has seen a steady, continuous increase. As cornering capability has improved, we’ve modified our lubrication and cooling strategy to match.
The earliest oil cooler you mention - the radiator end-tank style in the C6 Z51, removed 3.5kW of heat from the oil and deposited it into the main engine coolant system. The downsides of this method are the relatively small capacity limit and the oil-side restriction penalty. Moving any fraction of the oil from the engine to the radiator takes away from the main goal of the lubrication system which is first and foremost to supply the bottom end (main bearings) with good oil pressure. But in the Z51 package, the tradeoff was favorable and the cooling adequate for the operating envelope of the LS2 engine.
With the introduction of the C6 Z06 we had a chassis and tire package that allowed us to put much more power to the ground, compounded by an LS7 engine that loved to spin. Those elements drove us to add a much higher oil cooling capacity (roughly 16Kw) than an end-tank cooler could provide, so an air-to-oil cooler was selected as a ‘big hammer’ solution for the dry-sump motors, chosen for its ability to cool better at higher vehicle speeds. We made a conscious decision to go that route, as there are several downsides to air-to-oil coolers. They add airflow restriction, which reduces the effectiveness of the main radiator and impacts AC performance. There is unwanted oil-side restriction which takes some pressure potential from the main bearings. And as you mention, on cold days the oil will always be somewhat over-cooled. (Overcooling oil isn’t the worst thing, but it costs some fuel efficiency as colder oil has higher viscosity and more friction loss.) But for a car as track-oriented as the C6 Z06, this was the right trade-off to make, using a balanced take-off valve to bleed just enough oil to the cooler to satisfy cooling needs.
In the spirit of continuous improvement, in the 2009 ZR1 we increased oil cooler capacity further. We also needed to maintain higher main bearing oil pressure to support the huge horsepower increase of the LS9. That drove us to integrate the oil cooler as a liquid-liquid heat exchanger mounted as part of the engine assembly- a triple benefit, with more kW of heat rejection (almost 20Kw), reduced oil-side restriction, and elimination of the front-end airflow blockage of the previous air/oil cooler. This option also reduced the plumbing complexity, with only one small coolant circuit leaving the engine block to return to the main radiator coolant circuit. The downside is that the main radiator has to reject the heat extracted by this cooler, but the tradeoff is overall a net positive. We’ve been very happy with the integrated liquid-liquid oil cooler ever since we adopted it, as it has been a win-win over all of the previous alternatives in terms of capacity, restriction, and the ability to better regulate normal operating temperatures.
The Z/28 Camaro presented a unique challenge, with higher mass and gear ratios selected to carry very high RPM on track. It required a capacity increase in the liquid-liquid cooler system, and the team added a supplemental air/oil coolant radiator dedicated to providing colder water to the engine oil cooler. This had a double benefit of reducing bulk coolant temp and oil temp, but with a tradeoff consequence of added complexity and added mass.
As the Corvette chassis improves and continues to drive more lateral loads through the lubrication system, we are challenged to keep up with the increasing demand of racetrack use. We’ve gone from 3.5kW of oil cooling in the C6 Z51 to 21kW in today’s C7 Z06. You can be confident we’ll continue along this path as Corvette performance improvements dictate it.
08-10-2015, 03:05 PM
#2
Interesting reply with the info about the cooling power of the various options in kW. But I wonder how the "performance improvements dictate" this cooling performance as posted by Anthony from LG: https://www.corvetteforum.com/forums...post1589259014
LG Motorsports:
77 Degree day
328 oil temp
265 water temp
Stock Z07
10 mins, 12 seconds of run time on track. Then it went into limp home mode.
Change the mix all you want, it isn't going to solve that problem.
The car needs help....and it's still stock.
Don't worry...going back to the track with solutions. Stay tuned. "
Might need more cooling kW.
LG Motorsports:
77 Degree day
328 oil temp
265 water temp
Stock Z07
10 mins, 12 seconds of run time on track. Then it went into limp home mode.
Change the mix all you want, it isn't going to solve that problem.
The car needs help....and it's still stock.
Don't worry...going back to the track with solutions. Stay tuned. "
Might need more cooling kW.
08-10-2015, 03:24 PM
#3
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And I'll win that dollar, too.
I don't question the need for some work re: the car's cooling. But let's be careful what we're asking the GM engineers to do, otherwise we're going to end up with a car that costs way more than the Z06 does, and can't realistically be used for all-around duty.
If you want those things, IMHO, build your own race car.
08-10-2015, 04:17 PM
#4
Le Mans Master
I don't think it's necessarily fair to hold up Lou's results as the "standard" with respect to the C7 Z06. He tends to over-drive things, and is better suited being in a real race car. I'll bet a dollar he was driving the **** out of that Z06 to try and find its limits.
And I'll win that dollar, too.
I don't question the need for some work re: the car's cooling. But let's be careful what we're asking the GM engineers to do, otherwise we're going to end up with a car that costs way more than the Z06 does, and can't realistically be used for all-around duty.
If you want those things, IMHO, build your own race car.
And I'll win that dollar, too.
I don't question the need for some work re: the car's cooling. But let's be careful what we're asking the GM engineers to do, otherwise we're going to end up with a car that costs way more than the Z06 does, and can't realistically be used for all-around duty.
If you want those things, IMHO, build your own race car.
08-10-2015, 04:52 PM
#5
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08-10-2015, 04:55 PM
#6
I don't think it's necessarily fair to hold up Lou's results as the "standard" with respect to the C7 Z06. He tends to over-drive things, and is better suited being in a real race car. I'll bet a dollar he was driving the **** out of that Z06 to try and find its limits.
And I'll win that dollar, too.
I don't question the need for some work re: the car's cooling. But let's be careful what we're asking the GM engineers to do, otherwise we're going to end up with a car that costs way more than the Z06 does, and can't realistically be used for all-around duty.
If you want those things, IMHO, build your own race car.
And I'll win that dollar, too.
I don't question the need for some work re: the car's cooling. But let's be careful what we're asking the GM engineers to do, otherwise we're going to end up with a car that costs way more than the Z06 does, and can't realistically be used for all-around duty.
If you want those things, IMHO, build your own race car.
My Z51 overheats on track, coolant temp and M7 transmission temp, and if I modify it, I risk losing the warranty, as the GM Brand quality manager who is looking after my case keeps asking via my service manager if I have modified the car every time it has to go in for warranty repair for the AFM actuator failure.
I do not drive the **** out of the car but I drive it fast and steady, and I only bought it because it had the track option Z51 package with the marketing of the most track capable Corvette ever. I expected GM to provide sufficient cooling for the job, and they did not. Not building myself a race car. Porsches, Vipers and my GT-R can run all day on track without overheating, and I've never ever had a car which constantly needs to go to the dealer for repairs after every track day, 5 times now for the same identical repair.
Different engineering objectives I assume.
It's not like Lou is the only one here on this forum who has had overheating issues on track with the C7. Just one example.
08-10-2015, 05:59 PM
#7
Le Mans Master
08-10-2015, 07:22 PM
#8
I really appreciate Tadge and Richard detailed response. It Is good to understand why they made the changes to engine oil cooling. Interesting in that there is no mention of radiator engine oil cooling and liquid-liquid heat exchanger solutions providing the benefit of warming the engine oil during engine warm-up. Also, no comment on what is a good optimum oil temperature should be. I do have to disagree with one comment made about the liquid-liquid heat exchanger solution – “This option also reduced the plumbing complexity”. You’re adding a coolant line from the block to the exchanger and adding another coolant line from the exchanger to the radiator which the other solutions do not have. This increase plumbing complexity not reduces it and these extra coolant lines and connections increase the potential of leaks as time goes on.
I know that DeWitts is one of the vendors that sponsors this forum, it would be interesting to get some comments from them on their radiator oil coolers. It is my understanding that it is much larger than the OEM radiator oil cooler.
I know that DeWitts is one of the vendors that sponsors this forum, it would be interesting to get some comments from them on their radiator oil coolers. It is my understanding that it is much larger than the OEM radiator oil cooler.
08-10-2015, 08:01 PM
#9
C7 Z06 owners who want to lower their oil temperatures on track by using an aftermarket air/oil cooler would be increasing their "oil-side" restriction, no? Could lead to accelerated bearing wear?
08-11-2015, 10:38 AM
#10
Le Mans Master
I don't think it's necessarily fair to hold up Lou's results as the "standard" with respect to the C7 Z06. He tends to over-drive things, and is better suited being in a real race car. I'll bet a dollar he was driving the **** out of that Z06 to try and find its limits.
And I'll win that dollar, too.
I don't question the need for some work re: the car's cooling. But let's be careful what we're asking the GM engineers to do, otherwise we're going to end up with a car that costs way more than the Z06 does, and can't realistically be used for all-around duty.
If you want those things, IMHO, build your own race car.
And I'll win that dollar, too.
I don't question the need for some work re: the car's cooling. But let's be careful what we're asking the GM engineers to do, otherwise we're going to end up with a car that costs way more than the Z06 does, and can't realistically be used for all-around duty.
If you want those things, IMHO, build your own race car.
The thing we can all extract from this response is, these engineers have done the best they could do. Each individual engineer, many of whom I've talked to, are tasked with different challenges to solve. In the end, they make the very best of the circumstances and get as close to the goal as possible. The issue here was, some parameter of design was outside the envelope of reasonable possibility.
My opinion is, there were too many compromises made, and that brought the car outside of excellence. They are trying to compress too many jobs, into one machine and they are trying to further compress using that one core architecture to do too many things. I hate to use the term "watered down" but, when we have Corvette engineers having to design drivetrains to fit cadillac hood lines, then we add opened air to every chassis, then we have a universally better interior it equals one hell of an OVERALL nice car...but one with many compromises. Every car for sale has compromises, no doubt...but I think it's those compromises that have left this Z06 off track.
I don't think GM/Corvette necessarily missed the entire target with the Z06, but I certainly do think this car should've been a ZR1. I truly believe the purity of the Z06 should've been retained...even if it meant putting it aside for a while. I get that it's just a badge...just an RPO code, but I truly believe Corvette could've really built a long term image off that code...young people loved it, older folks also liked it but they didn't like that it was set in its ways. The moment Z06 became a retiree comfy car, is the moment it lost its edge....that's all there is to it. Debuting a C7ZR1 at a 30k discount could've been a HOME RUN, and the Z06 could've "switched places" essentially...become that more elitist, albeit more expensive car that did GT3 like things...but KILLED it...allowed you to drive the "****" out of it.
As a result they lost me as a buyer...which is why I still haven't sold my C5Z, and I imagine some others as well. I am currently cautious about where GM is taking this car. I watch the C7R eagerly, and wish I the z06 badge on its fender were represented on the street in such a profoundly successful manner. As it stands, it appears I will buy a Z51 instead and pick from the Z06 parts bin to construct my own compromise...I guess I can at least thank them for the parts though. I can't deny Corvettes chassis, and many other elements are excellence...but I have to do the work myself I guess.
08-11-2015, 11:41 AM
#11
To be fair to the team, the car isn't slow. It just has questionable endurance. With sharing the engine with Cadillac (not a Corvette first), being an convertible, nicer interior, etc, I've often asked if the Z06 was exactly as it is now, but had no cooling issues, would anybody still have a problem with it?
My hope, at this point, is that the car sells well enough to justify, now and in the future, the portfolio of base car, higher performance GT that can be tracked (like Camaro ZL1), and a stripper track day special (like Camaro Z28). It works for Porsche, Camaro, Mustang, and Corvette C6, so I don't know why it wasn't considered for C7 (at least from what it appears so far).
08-11-2015, 12:23 PM
#12
E-Ray, 3LZ, ZER, LIFT
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I really appreciate Tadge and Richard detailed response. It Is good to understand why they made the changes to engine oil cooling. Interesting in that there is no mention of radiator engine oil cooling and liquid-liquid heat exchanger solutions providing the benefit of warming the engine oil during engine warm-up. Also, no comment on what is a good optimum oil temperature should be. I do have to disagree with one comment made about the liquid-liquid heat exchanger solution – “This option also reduced the plumbing complexity”. You’re adding a coolant line from the block to the exchanger and adding another coolant line from the exchanger to the radiator which the other solutions do not have. This increase plumbing complexity not reduces it and these extra coolant lines and connections increase the potential of leaks as time goes on.
Second can only comment on my C6 Z51 with manual trans and how I thought cooling the differential was cleaver and reduced cooling line complexity. It used short lines to a small liquid to liquid heat exchanger (it used cooled trans return oil, see pic.) The manual trans was cooled like an automatic, using the engine radiator. However that required long trans oil lines and took heat removal capacity away from the radiator. Sounds like the C7 needs all the engine cooling it can get (albeit have had no problems on 100+ degree day-but I don’t track.) Engine oil temp runs much lower than in my modified Corvair many years ago!
I was reminded of the decision I had to make with the modified ZZ502/502 engine in my ’34 ProStreet Rod. Even with one of the largest Griffon radiators, cooling that engine would not be easy. Used two electric pusher and a large engine driven puller fan and radiator shroud. Did not want to add the extra heat load burden of cooling the race prepared TH-400 trans so didn't use that location but rather added a B&W external heat exchanger (pic below.) Would seem to me the solution to the trans cooling issue is an added cooler in series with the existing one. Would have to find a place to put it and probably best with a fan (in fact I added a sheet metal air duct to my B&W trans cooler.)
For me that is the fun of racing or even tracking, do a few small things to make your car better then the next guy! As someone noted that is what LG Motorsports may be doing so they can offer an aftermarket kit! For engine overheating I would install a larger radiator. I have LG Motorsports CF side skirts and hood vent, good folks.
Just the opinion of an old Hot Rodder!
Liquid to Liquid Heat Exchanger Used Cooled, Return Manual Trans Oil to Cool Differential Oil
For Street Rod Added an External B&W Trans Cooler Instead of Using the Engine Radiator to Avoid Reducing it's Cooling Capacity
Last edited by JerryU; 08-11-2015 at 12:33 PM.
08-11-2015, 03:46 PM
#13
Pro
Personally I feel GM/Corvette should offer a Track Pak option, develop larger coolers/fans/radiators etc. and allow those who will be tracking their car often to select that option. They could offer lighter wheels, more track tuned suspension, areo, etc. Other automakers do it, this way you have an option for those who want to track their cars and for those who do not, they do not have to pay the extra $$$ for the upgrades. With the new Dodge Viper ACR looming, I think it will be a wise choice to offer such a package.
Just my two cents...
Just my two cents...
08-11-2015, 05:17 PM
#14
E-Ray, 3LZ, ZER, LIFT
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Personally I feel GM/Corvette should offer a Track Pak option, develop larger coolers/fans/radiators etc. and allow those who will be tracking their car often to select that option. They could offer lighter wheels, more track tuned suspension, areo, etc. Other automakers do it, this way you have an option for those who want to track their cars and for those who do not, they do not have to pay the extra $$$ for the upgrades. With the new Dodge Viper ACR looming, I think it will be a wise choice to offer such a package.
Just my two cents...
Just my two cents...
And they don't have to spend much engineering time, just get aftermarket folks to supply the products to them and check their fit, finish and fuction. The CNC ported aluminum heads on my ZZ502 big block and the port matched intake manifold are made by Edelbrock, for example. Lots of places to sort wheels etc. If they don't want to deal with the production issues they could put them in a package that the dealer installs. Like the old days of headers in the trunk! My 8.2 Liter crate engine was only available from authorized "performance parts dealers." Could do the same and have special training for dealers who wish to participate.
Last edited by JerryU; 08-11-2015 at 05:59 PM.
08-11-2015, 06:49 PM
#15
Le Mans Master
I can appreciate your statement, but is it fair to expect less from this car? Is this the standard for which we want to judge the current, best Corvette being offered in the lineup? A "drive it hard, but not too hard, and certainly don't drive the '****' out of it" type of benchmark standard seems like a failure approach.
The thing we can all extract from this response is, these engineers have done the best they could do. Each individual engineer, many of whom I've talked to, are tasked with different challenges to solve. In the end, they make the very best of the circumstances and get as close to the goal as possible. The issue here was, some parameter of design was outside the envelope of reasonable possibility.
My opinion is, there were too many compromises made, and that brought the car outside of excellence. They are trying to compress too many jobs, into one machine and they are trying to further compress using that one core architecture to do too many things. I hate to use the term "watered down" but, when we have Corvette engineers having to design drivetrains to fit cadillac hood lines, then we add opened air to every chassis, then we have a universally better interior it equals one hell of an OVERALL nice car...but one with many compromises. Every car for sale has compromises, no doubt...but I think it's those compromises that have left this Z06 off track.
I don't think GM/Corvette necessarily missed the entire target with the Z06, but I certainly do think this car should've been a ZR1. I truly believe the purity of the Z06 should've been retained...even if it meant putting it aside for a while. I get that it's just a badge...just an RPO code, but I truly believe Corvette could've really built a long term image off that code...young people loved it, older folks also liked it but they didn't like that it was set in its ways. The moment Z06 became a retiree comfy car, is the moment it lost its edge....that's all there is to it. Debuting a C7ZR1 at a 30k discount could've been a HOME RUN, and the Z06 could've "switched places" essentially...become that more elitist, albeit more expensive car that did GT3 like things...but KILLED it...allowed you to drive the "****" out of it.
As a result they lost me as a buyer...which is why I still haven't sold my C5Z, and I imagine some others as well. I am currently cautious about where GM is taking this car. I watch the C7R eagerly, and wish I the z06 badge on its fender were represented on the street in such a profoundly successful manner. As it stands, it appears I will buy a Z51 instead and pick from the Z06 parts bin to construct my own compromise...I guess I can at least thank them for the parts though. I can't deny Corvettes chassis, and many other elements are excellence...but I have to do the work myself I guess.
The thing we can all extract from this response is, these engineers have done the best they could do. Each individual engineer, many of whom I've talked to, are tasked with different challenges to solve. In the end, they make the very best of the circumstances and get as close to the goal as possible. The issue here was, some parameter of design was outside the envelope of reasonable possibility.
My opinion is, there were too many compromises made, and that brought the car outside of excellence. They are trying to compress too many jobs, into one machine and they are trying to further compress using that one core architecture to do too many things. I hate to use the term "watered down" but, when we have Corvette engineers having to design drivetrains to fit cadillac hood lines, then we add opened air to every chassis, then we have a universally better interior it equals one hell of an OVERALL nice car...but one with many compromises. Every car for sale has compromises, no doubt...but I think it's those compromises that have left this Z06 off track.
I don't think GM/Corvette necessarily missed the entire target with the Z06, but I certainly do think this car should've been a ZR1. I truly believe the purity of the Z06 should've been retained...even if it meant putting it aside for a while. I get that it's just a badge...just an RPO code, but I truly believe Corvette could've really built a long term image off that code...young people loved it, older folks also liked it but they didn't like that it was set in its ways. The moment Z06 became a retiree comfy car, is the moment it lost its edge....that's all there is to it. Debuting a C7ZR1 at a 30k discount could've been a HOME RUN, and the Z06 could've "switched places" essentially...become that more elitist, albeit more expensive car that did GT3 like things...but KILLED it...allowed you to drive the "****" out of it.
As a result they lost me as a buyer...which is why I still haven't sold my C5Z, and I imagine some others as well. I am currently cautious about where GM is taking this car. I watch the C7R eagerly, and wish I the z06 badge on its fender were represented on the street in such a profoundly successful manner. As it stands, it appears I will buy a Z51 instead and pick from the Z06 parts bin to construct my own compromise...I guess I can at least thank them for the parts though. I can't deny Corvettes chassis, and many other elements are excellence...but I have to do the work myself I guess.
08-11-2015, 06:56 PM
#16
Many thanks to JVP, Tadge & Richard for the comprehensive reply.
Among all the differing technical opinions and philosophical approaches I still think the 06 is the car I want because of what it does.
From an engineering stand point I truly cannot understand the lack of appreciation for the heat/performance/reliability/durability dichotomy.
The critics keep poking at this in absolute terms (perfection from a 100K car...) when we all know it is all relative to competition and alternative offerings. Please look at the total recall for the GT3 and 918...
The quickest and cheapest way for Tadge to fix the limp mode and overheating would be to "mask it" take away the safeguard limp mode (easy), take away the 100K warranty (easy - everybody else does it...)and let "the few" drive the thing to the ground!
FIXED!
Cheers
PS - Isn't the C706 the best selling 06 ever!?
Among all the differing technical opinions and philosophical approaches I still think the 06 is the car I want because of what it does.
From an engineering stand point I truly cannot understand the lack of appreciation for the heat/performance/reliability/durability dichotomy.
The critics keep poking at this in absolute terms (perfection from a 100K car...) when we all know it is all relative to competition and alternative offerings. Please look at the total recall for the GT3 and 918...
The quickest and cheapest way for Tadge to fix the limp mode and overheating would be to "mask it" take away the safeguard limp mode (easy), take away the 100K warranty (easy - everybody else does it...)and let "the few" drive the thing to the ground!
FIXED!
Cheers
PS - Isn't the C706 the best selling 06 ever!?
08-11-2015, 07:11 PM
#17
Former Vendor
[QUOTE=grcor;1590242445
I know that DeWitts is one of the vendors that sponsors this forum, it would be interesting to get some comments from them on their radiator oil coolers. It is my understanding that it is much larger than the OEM radiator oil cooler.[/QUOTE]
The in-tank coolers used on 2005-06 Z51 were 3 plate/ stainless steel devices and as noted provided 3.5kw of heat transfer. We use a seven plate aluminum cooler for this application and it provides 7kw of heat transfer.
The C7 radiator has very shallow end tanks and it does not provide enough room for an internal cooler. The air type offer a significant increase and that is our focus now.
I know that DeWitts is one of the vendors that sponsors this forum, it would be interesting to get some comments from them on their radiator oil coolers. It is my understanding that it is much larger than the OEM radiator oil cooler.[/QUOTE]
The in-tank coolers used on 2005-06 Z51 were 3 plate/ stainless steel devices and as noted provided 3.5kw of heat transfer. We use a seven plate aluminum cooler for this application and it provides 7kw of heat transfer.
The C7 radiator has very shallow end tanks and it does not provide enough room for an internal cooler. The air type offer a significant increase and that is our focus now.
08-11-2015, 07:13 PM
#18
Safety Car
This is why I have been advocating for nearly 6 months for someone to build an auxiliary radiator for M7 cars located in the auto transmission's cooler place. It will be a safe way to add cooling without screwing with the oil pressure. Low and behold even the Z28 does the same thing. We now have three cars in GM's stable that have significant cooling advantages over the Corvette, the Z28, the 2016 Camaro, and the 2016 CTS-V. Do we have to wait for the C8 Corvette to track a modern day Corvette? Alternatively we can add an air/oil oil cooler just to find out the engine grenades itself.
I don't question the need for some work re: the car's cooling. But let's be careful what we're asking the GM engineers to do, otherwise we're going to end up with a car that costs way more than the Z06 does, and can't realistically be used for all-around duty.
If you want those things, IMHO, build your own race car.
If you want those things, IMHO, build your own race car.
Yay you believe the cooling is inadequate! But really, the cost issue is not as big as you think. People pay $2,000 to get chrome wheels on this car. $2,000 in extra cooling mods would do it.
In truth, the proof is out there already. Just look at any of the new GM (non-corvette) sports cars released in the last year or in the pipeline. They all fix the cooling without a noticeable jump in price. The cooling is not even an option. So what are we asking the engineers to do? Please gives us the same cooling that Camaros and Cadillacs already have. Why is Corvette the neutered car in the lineup? You can't even spec a Camaro or CTS-V for what I paid for my 'Vette.
The thing we can all extract from this response is, these engineers have done the best they could do. Each individual engineer, many of whom I've talked to, are tasked with different challenges to solve. In the end, they make the very best of the circumstances and get as close to the goal as possible. The issue here was, some parameter of design was outside the envelope of reasonable possibility.
08-11-2015, 08:50 PM
#19
I'm Batman..
Pro Mechanic
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I think this was a good response from them this time. As for previous responses, I am starting to get disappointed with the position they are taking. I wish we had a way to publicly (as a large group, NOT individually) confront GM about the many different concerns we have with these cars. I was hoping that this section of the forum would yield more "commitment to solutions" from GM. Its more like just technical conversation with a publicist though. I guess I am just late to the party in realizing that while these response we are getting do contain some good technical information, NONE of them offer a commitment to a solution. They do not acknowledge that there are problems that they will take responsibility for, or worse, they play coy to known issues with responses that indicated things like "GM didnt have that issue when we tested". JVP please do not take this as a reflection of how Ask Tadge is managed as I think you do a good job policing this section. Its just a catch 22 here. We need to be more aggressive with our questions and statements to GM, and if we do, they may pull out of Ask Tadge all together.
08-11-2015, 10:03 PM
#20
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Nothing will be engineered overnight. It's not how large automotive manufacturers work, specially when it comes to things as complicated as the power train of a car like the Vette. I know some people have said they want an OEM solution to this because those are generally, "engineered properly," and yet in the same breath continue to complain that a solution hasn't been provided yet. That's a fairly obvious contradiction in wants. It takes time to engineer things properly because unlike the aftermarket, the OEM has to make sure they do the usual 100K mile testing, etc, etc. And they have to make sure that whatever they do change doesn't have other bad consequences to the power train or other parts of the car.
If being an automotive engineer were easy, we'd all be doing it.
