Giday there,
I have some broad questions but am wondering what the 308's were notorious for, like bad oil surge etc.
What power figure did the early engines come out with?
How much power can the stock internals handle?
If there are cons to the engines what would be the pros?
Thanks in advance
308 infomation
Started by
_01dencwe_
, May 02 2006 05:33 PM
22 replies to this topic
#2
lakeside
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Posted 03 May 2006 - 01:25 PM
wrecking the rear lobes of the cam shaft
#3
_[2_FLY]_
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Posted 03 May 2006 - 07:10 PM
I`ve found they are bad for spinning big end bearings if revved too hard or poor oil delivery.
They are a strong motor if treated appropriately. Mine makes around the 400hp mark at the fly and still runs stock crank, stock rods and stock rod bolts with a cheap set of 40 thou over pistons. With a little head work and a mild cam they are fantastic fun for not alot of money.
They are a strong motor if treated appropriately. Mine makes around the 400hp mark at the fly and still runs stock crank, stock rods and stock rod bolts with a cheap set of 40 thou over pistons. With a little head work and a mild cam they are fantastic fun for not alot of money.
#4
_01dencwe_
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Posted 03 May 2006 - 08:06 PM
Whats the redline and rev limiter on a stock 308?
#5
_[BOTTLEDUP]_
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Posted 04 May 2006 - 02:27 AM
They have no rev limiter
I'd not turn a stock engine past 5500.
Factory tolerances from Holden are garbage... They are renowned for having bad oil pressure when hot.
Don't ever fit a HV oil pump and then use a heavy weight oil with will cause excessive wear on the cam.
The problem lakside refers to is due to the shocking clearance in the factory cam tunnel... Sometimes as much as 6 or 7 thou. Another mistake is using Chev hydraulic lifters.
I'd not turn a stock engine past 5500.
Factory tolerances from Holden are garbage... They are renowned for having bad oil pressure when hot.
Don't ever fit a HV oil pump and then use a heavy weight oil with will cause excessive wear on the cam.
The problem lakside refers to is due to the shocking clearance in the factory cam tunnel... Sometimes as much as 6 or 7 thou. Another mistake is using Chev hydraulic lifters.
#6
_JBM_
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Posted 04 May 2006 - 11:44 AM
When they were first raced they had oil surge problems. Fitting a windage tray in the sump will help in this area.
They also leak oil from the sump, rocker covers and rear main crank seal.
James
They also leak oil from the sump, rocker covers and rear main crank seal.
James
Edited by JBM, 04 May 2006 - 11:46 AM.
#7
_01dencwe_
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Posted 04 May 2006 - 04:41 PM
I have a high volume pump on with pennzoil 25/50, is this the bad combination you speak of?,May 4 2006, 02:27 AM] Don't ever fit a HV oil pump and then use a heavy weight oil with will cause excessive wear on the cam.
I am running a pretty much stock 308 and just potter around town. Should I bother buying a standard pump as the HV is pretty new?
Cheers
#8
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Posted 04 May 2006 - 09:00 PM
People fit the HV pump to try and rectify the lack of oil pressure at idle, but its the equivalent of papering over the cracks in a wall... It doesn't fix the prob.
#9
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Posted 05 May 2006 - 10:59 AM
So would any one suggest refitting the standard pump?,May 4 2006, 09:00 PM] People fit the HV pump to try and rectify the lack of oil pressure at idle, but its the equivalent of papering over the cracks in a wall... It doesn't fix the prob.
#10
gtrboyy
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Posted 05 May 2006 - 04:11 PM
Have you got an oil pressure guage on your car & checked your oil pressure in various driving conditions like cold,warmed up,accellarating,stopping etc.
#11
_01dencwe_
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Posted 05 May 2006 - 09:02 PM
Oil pressure is good excluding when it is at operating temperature and idoling - gets around 10 - 20 psi.Have you got an oil pressure guage on your car & checked your oil pressure in various driving conditions like cold,warmed up,accellarating,stopping etc.
Will I be damaging the engine with the HV pump on compared to the standard?
#12
_devilsadvocate_
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Posted 05 May 2006 - 09:08 PM
Is there a fix?,May 4 2006, 09:00 PM] People fit the HV pump to try and rectify the lack of oil pressure at idle, but its the equivalent of papering over the cracks in a wall... It doesn't fix the prob.
#13
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Posted 05 May 2006 - 11:15 PM
Blue printing the motor will fix the clearance problems for bearings.
Improve the flow of oil from the top of the motor back to sump be removing casting flash from the valley and putting radiuses on the oil gallery holes may help.
You could also go to a dry sump setup if you have the cash, this is the best method to improve oil distribution in the motor.
The oil viscosity or weight should be selected for the normal ambient temperature that the car will be operated in, ie cold areas 5W, 5W-10, 5W-20 or hot areas 20W-50 etc. Your hand book or service manual should have chart showing this.
James
Improve the flow of oil from the top of the motor back to sump be removing casting flash from the valley and putting radiuses on the oil gallery holes may help.
You could also go to a dry sump setup if you have the cash, this is the best method to improve oil distribution in the motor.
The oil viscosity or weight should be selected for the normal ambient temperature that the car will be operated in, ie cold areas 5W, 5W-10, 5W-20 or hot areas 20W-50 etc. Your hand book or service manual should have chart showing this.
James
#14
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Posted 06 May 2006 - 12:10 AM
Isnt the problem quoted, low oil pressure at idle when hot/warm/operating temp.The oil viscosity or weight should be selected for the normal ambient temperature that the car will be operated in, ie cold areas 5W, 5W-10, 5W-20 or hot areas 20W-50 etc. Your hand book or service manual should have chart showing this.
James
Wouldnt you want to be using an oil with a something/50 rating regardless of temp since it is the 2nd number which is more a indicator of the oil viscosity when at operating temp.
Perhaps a 10W/60 in winter(typically only available in syn) and 25W/60 in summer?
#15
gtrboyy
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Posted 06 May 2006 - 11:10 AM
I was told a common problem for oil pressure drop is too much clearance from the cam bearings on a std engine.
#16
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Posted 06 May 2006 - 11:52 AM
Holden must be wrong about what grades of oil should be used in their engines.Isnt the problem quoted, low oil pressure at idle when hot/warm/operating temp.
The oil viscosity or weight should be selected for the normal ambient temperature that the car will be operated in, ie cold areas 5W, 5W-10, 5W-20 or hot areas 20W-50 etc. Your hand book or service manual should have chart showing this.
James
Wouldnt you want to be using an oil with a something/50 rating regardless of temp since it is the 2nd number which is more a indicator of the oil viscosity when at operating temp.
Perhaps a 10W/60 in winter(typically only available in syn) and 25W/60 in summer?
The oil weight range is designed to give protection on start up as well as at normal running temperature, hence the importance of the ambient temperature to give the ideal oil weight.
I didn't think that 1 grade of oil could have such a wide viscosity range.
I would only use a high 60 grade oil in an older worn engine.
James
Edited by JBM, 06 May 2006 - 11:59 AM.
#17
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Posted 06 May 2006 - 12:53 PM
That's correct. Holden's feed the cam tunnel first, from which there is an off shoot to the crank journals. The problem lies in the excessive clearance between the cam and the cam bearings, in some cases holdens have had as much as 0.007" clearance.I was told a common problem for oil pressure drop is too much clearance from the cam bearings on a std engine.
We always use 0.002" undersize cam bearings to rectify it, and in an engine that is warm you will usually see an improvement of 10 or so psi at idle with a std oil pump.
#18
_devilsadvocate_
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Posted 06 May 2006 - 02:21 PM
James, I think the case with the 308 is that it behaves as an older engine when idling when warm, ie the clearances are too high and oil pressure drops, which is not always an indication that their is poor oil flow through the engine(it usually means oil flow has increased), just that certain parts,ie bearings arent getting the designed/intended oil pressure delivery.Holden must be wrong about what grades of oil should be used in their engines.
I would only use a high 60 grade oil in an older worn engine.
James
So a fix would be too either have the bearing prob fixed as bottledup suggests or use an oil with a higher viscosity at operating temp. Obviously bottledup's fix would be better for the whole engine, but if not using a higher viscosity oil would be necessary?
Im not sure we have the same understanding of the oil ratings on multigrade oils?
The first number 20 in 20W/50 is an indicator of the oils ability to flow when cold.
From memory it means the oil has the same viscosity as a 20W monograde oil at a nominal low temp, possibly 0C.
The higher value means it has the same viscosity as a 50W monograde oil at a nominal higher temp, possibly 100C.
So its possible to have an oil that will not get too thin when hot, and not be too thick when cold. ie 10W/60 syn.
#19
_01dencwe_
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Posted 07 May 2006 - 04:50 PM
So what was the conclusion? Should I leave on the HV or replace with standard pump?
#20
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Posted 08 May 2006 - 12:06 AM
Personally I'd pull the engine, fix it properly and then fit a new std volume oil pump.
If that's out of the question I'd leave it for now.
If that's out of the question I'd leave it for now.
#21
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Posted 08 May 2006 - 12:35 PM
To answer this problem correctly the effect of Bernouli's equation needs to be considered. Google it if you dont know about it.
Bernouli's Equation
In a closed fluid system we can relate the pressure at a point, p, to the density, r, the elevation at a point, y, and the speed of the fluid at a point, v, by Bernouli's Equation. It can be written as
p1 + r g y1 + � r v12 = p2 + r g y2 + � r v22
Alternatively, this equation can be written as
p + r g y + � r v2 = constant
This equation explains the relationship between pressure, velocity and flow rate for gaseous and liquid fluids.
The pressure in a fluid system remains constant at a certain point with a constant pressure applied to the system ie from a pump. Loses of pressure will occur due to roughness of the pipe or passage the fluid passes through, sudden enlargements or contractions and changes of direction, these are called K factors. These K factors determine how much pressure will be lost between one point in a system compared to another.
If we assume that there are no K factor losses within a system a change in pipe size will decrease the velocity of the fluid, decrease the pressure and the flow rate will remain the same, once the pipe becomes smaller the pressure will increase, the velocity will increase and the flow rate will still be the same.
The flow rate remains the same because the pump hasn't changed speeds.
While idling the oil pump speed is lower, decreasing the flow rate and velocity but the pressure is contant as the same amount of torque is applied to the fluid by the pump it just happens less often. Its the flow rate at low speeds that affects the engines lubrication not the pressure.
As a chain requiring lubrication turns faster its not the oil pressure delivery that is important it is the drips per minute or rate that it is applied to the chain that is important. Therefore a slow chain may requre 50 drips per minute for lubrication but a fast chain requires an oil bath for lubrication.
Therefore a high volume oil pump will deliver more oil per minute than a standard pump, that is why its called a HIGH VOLUME oil pump not a HIGH PRESSURE oil pump.
James
Bernouli's Equation
In a closed fluid system we can relate the pressure at a point, p, to the density, r, the elevation at a point, y, and the speed of the fluid at a point, v, by Bernouli's Equation. It can be written as
p1 + r g y1 + � r v12 = p2 + r g y2 + � r v22
Alternatively, this equation can be written as
p + r g y + � r v2 = constant
This equation explains the relationship between pressure, velocity and flow rate for gaseous and liquid fluids.
The pressure in a fluid system remains constant at a certain point with a constant pressure applied to the system ie from a pump. Loses of pressure will occur due to roughness of the pipe or passage the fluid passes through, sudden enlargements or contractions and changes of direction, these are called K factors. These K factors determine how much pressure will be lost between one point in a system compared to another.
If we assume that there are no K factor losses within a system a change in pipe size will decrease the velocity of the fluid, decrease the pressure and the flow rate will remain the same, once the pipe becomes smaller the pressure will increase, the velocity will increase and the flow rate will still be the same.
The flow rate remains the same because the pump hasn't changed speeds.
While idling the oil pump speed is lower, decreasing the flow rate and velocity but the pressure is contant as the same amount of torque is applied to the fluid by the pump it just happens less often. Its the flow rate at low speeds that affects the engines lubrication not the pressure.
As a chain requiring lubrication turns faster its not the oil pressure delivery that is important it is the drips per minute or rate that it is applied to the chain that is important. Therefore a slow chain may requre 50 drips per minute for lubrication but a fast chain requires an oil bath for lubrication.
Therefore a high volume oil pump will deliver more oil per minute than a standard pump, that is why its called a HIGH VOLUME oil pump not a HIGH PRESSURE oil pump.
James
Edited by JBM, 08 May 2006 - 12:38 PM.
#22
_devilsadvocate_
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Posted 10 May 2006 - 06:04 AM
Not sure what your final reccommendation is there James?
Not an expert on what goes on inside an engine re oil passages etc, but do understand basic fluid dynamics.
Like to think of it like a garden sprinkler system where the is a pvc pipe with individual sprays on it.
The sprays are designed with garden tap pressures in mind, ie 80-100psi to work well. The actual vol of water used is quite low compared to a sprinkler etc.
So the system will work well with only a quarter turn of the tap.
If however, one of the sprays nozzles is spat out of the line, then there is a large open leak to the system, through which most of the water will then go and the rest of the sprays basically die, whether they are up or down stream of the hole.
This is what I picture happening with the bearings in the 308 that have too much clearance, there is a large flow through them effectively dropping the delivery volume at other points.
In the garden system, one can turn the tap to full bore to try and maintain flow on the other nozzles, which would be equivalent to fitting a high volume oil pump in the 308.
Using a higher viscosity oil would also to some extent achieve the same thing.
James, the figures you quote on oil, are from a 30 year old owners manual?, using a 10W/30 oil in an engine that is suffering from low oil pressure when warm wouldnt be a good idea, regardless of the ambient temp. With the oils available today, one doesnt have to compromise as much if wanting an oil that will flow below 0C and protect the engine at running temps.
Not an expert on what goes on inside an engine re oil passages etc, but do understand basic fluid dynamics.
Like to think of it like a garden sprinkler system where the is a pvc pipe with individual sprays on it.
The sprays are designed with garden tap pressures in mind, ie 80-100psi to work well. The actual vol of water used is quite low compared to a sprinkler etc.
So the system will work well with only a quarter turn of the tap.
If however, one of the sprays nozzles is spat out of the line, then there is a large open leak to the system, through which most of the water will then go and the rest of the sprays basically die, whether they are up or down stream of the hole.
This is what I picture happening with the bearings in the 308 that have too much clearance, there is a large flow through them effectively dropping the delivery volume at other points.
In the garden system, one can turn the tap to full bore to try and maintain flow on the other nozzles, which would be equivalent to fitting a high volume oil pump in the 308.
Using a higher viscosity oil would also to some extent achieve the same thing.
James, the figures you quote on oil, are from a 30 year old owners manual?, using a 10W/30 oil in an engine that is suffering from low oil pressure when warm wouldnt be a good idea, regardless of the ambient temp. With the oils available today, one doesnt have to compromise as much if wanting an oil that will flow below 0C and protect the engine at running temps.
Edited by devilsadvocate, 10 May 2006 - 06:18 AM.
#23
_JBM_
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Posted 11 May 2006 - 11:15 PM
The viscosity guide is from the Ellerys VB-VK Manual.
With the cam bearing having more clearance the oil slows down as it passes through larger gap because it has to fill a larger space.
A thicker oil will reduce the flow rate and velocity in any circumstance, it's "r" in Bernoulis equation.
I would fix the cam bearing clearance or fit a high volume pump.
James
With the cam bearing having more clearance the oil slows down as it passes through larger gap because it has to fill a larger space.
A thicker oil will reduce the flow rate and velocity in any circumstance, it's "r" in Bernoulis equation.
I would fix the cam bearing clearance or fit a high volume pump.
James
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