My oil control/ should i get a dry sump vent?
09-09-2013, 02:31 PM
#31
Nordschleife Master
Displacement is one of the most important determinants of windage and oiling problems. Stroking or overboring the engine is the second easiest way to get oiling problems to show up. The easiest way is to build / run the engine in a way that it doesn't have ring seal and lets out a huge amount of blowby thru the rings.
09-09-2013, 02:37 PM
#32
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Tuomo-
Let the wookie win.
-Rob
Let the wookie win.
-Rob
09-09-2013, 03:37 PM
#34
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you all know my comments to the crankcase venting thing. keep it all stock. nothing has seemed to work with any of the set ups discussed here and all out solving a problem that i feel doesnt exist, in addition to what greg said. these are street cars, fix them up, put on suspension , wheels and tires and make them look as they should, but stay away from the engine, unless you are stroking it. (personal opinion).
remember ive beat the snot of these cars for over 130 races, 15 years of racing and have NO issues with the car and its stock components (sans the headers and racing exhaust i use because its a race car). its an amazing vehicle. no one has done what ive done as far as reliability and performance with any other car out there. Porsche really made a gem with the 928.
the supercharger, turbo efforts seem to be just a lot of time and money for limited gain. seems a stroker is a clean way to get performance with not a lot of work and it still stays mostly all porsche except for the crank and rods.
remember ive beat the snot of these cars for over 130 races, 15 years of racing and have NO issues with the car and its stock components (sans the headers and racing exhaust i use because its a race car). its an amazing vehicle. no one has done what ive done as far as reliability and performance with any other car out there. Porsche really made a gem with the 928.
the supercharger, turbo efforts seem to be just a lot of time and money for limited gain. seems a stroker is a clean way to get performance with not a lot of work and it still stays mostly all porsche except for the crank and rods.
Too late to leave it stock, he already has a supercharger installed. Changes the dynamics of the crank case breather system when the manifold has positive air pressure.
George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com
09-09-2013, 04:20 PM
#35
Race Car
My car has good quality cats and has passed emissions with flying colors for years. I also get 23mpg on the highway. I just have to close the breather system and it will be all set; working on it.
Dan
'91 928GT S/C
475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ft
09-09-2013, 05:25 PM
#36
Rennlist Member
Thread Starter
you all know my comments to the crankcase venting thing. keep it all stock. nothing has seemed to work with any of the set ups discussed here and all out solving a problem that i feel doesnt exist, in addition to what greg said. these are street cars, fix them up, put on suspension , wheels and tires and make them look as they should, but stay away from the engine, unless you are stroking it. (personal opinion).
remember ive beat the snot of these cars for over 130 races, 15 years of racing and have NO issues with the car and its stock components (sans the headers and racing exhaust i use because its a race car). its an amazing vehicle. no one has done what ive done as far as reliability and performance with any other car out there. Porsche really made a gem with the 928.
the supercharger, turbo efforts seem to be just a lot of time and money for limited gain. seems a stroker is a clean way to get performance with not a lot of work and it still stays mostly all porsche except for the crank and rods.
remember ive beat the snot of these cars for over 130 races, 15 years of racing and have NO issues with the car and its stock components (sans the headers and racing exhaust i use because its a race car). its an amazing vehicle. no one has done what ive done as far as reliability and performance with any other car out there. Porsche really made a gem with the 928.
the supercharger, turbo efforts seem to be just a lot of time and money for limited gain. seems a stroker is a clean way to get performance with not a lot of work and it still stays mostly all porsche except for the crank and rods.
09-10-2013, 01:22 AM
#37
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you all know my comments to the crankcase venting thing. keep it all stock. nothing has seemed to work with any of the set ups discussed here and all out solving a problem that i feel doesnt exist, in addition to what greg said.
Hey MK, sorry, but some of us just have to push the envelope, and that involves some things that others may not find palletable such as spending a small fortune on engineering a solution to the problem of blowby that happens when you have blowby issues. Again, not all 928's have this, and it depends on the condition and load of the engine as you surely know!
these are street cars, fix them up, put on suspension , wheels and tires and make them look as they should, but stay away from the engine, unless you are stroking it. (personal opinion).
Have to disagree with this, as you can double the power output of the engine with forced induction and only place a 5% increased load on the rotating assembley, not to mention that the soft pressure reduces the load at certain stages using forced induction..
Compared to increasing the piston speed from which puts and incredible amount of stress on the rotating assembley. There is also increased stress on the rotating assembley with piston speed compared to forced induction due to the way the combustion cycle happens.. Anyway, too much to explain in detail here.. As an engineer with access to all those formulas, I am sure you can calculate the respective loads on the assembley yourself.. However, when accounting for the load of forced induction, don't forget that the rods won't fail in compression, but in tension, and this is minimized in forced induction vs normally aspirated.....
remember ive beat the snot of these cars for over 130 races, 15 years of racing and have NO issues with the car and its stock components (sans the headers and racing exhaust i use because its a race car). its an amazing vehicle. no one has done what ive done as far as reliability and performance with any other car out there. Porsche really made a gem with the 928.
the supercharger, turbo efforts seem to be just a lot of time and money for limited gain.
What's limited for you may not be the case with others, I think the Kuhn setup is a really good example of a very powerful setup that is very well done, and with 800 RWHP, it is pretty good value for $$$... To go that fast, you can basically get an S4 in great shape for $15K, and add another $20 K in mods, and drive your hearts content, and beat any stroker in acceleration and top speed. Considering a stroker motor is about $35K and puts out way less than 800 at the tires, and the available torque across the powerband is exceptional in the turbo car, the turbo car is a screaming deal.
I say this is without considering the increased stroke on a stroker will increase the wear on the rings from the extra travel in stroke, and am also not counting piston speed and increase load on the rod cap when it yanks the piston from TDC on the intake cycle...
Granted they are both works of art, but one produces a lot more power for the same $$$$.. Value for $$$ is very easy to calculate in that example..
In addition, because I am having my system CFD analyzed, does that make it less of a value to me? If you say 'yes', then that is only your opinion, not my value system.. And that's fine, but again only your opinion...
The same can be said for shifting to a full sequential ECU with COP, and other control and or engineering parameters.. Is it less value to use a better ECU instead of the LH...??
What about the guys that run the ORR, or the Texas mile, or the Mojave mile... Is it less beneficial to them to do all they do, when pretty much anyone can fly to Germany, rent a mid size turbo diesel from Audi/BMW and go 250 kmH all day long using less fuel than a gas car on the events in the USA, and travel faster for longer for less money, should we all fly to europe and not use our cars in the US events....?? I kind of doubt that any of those people will agree with you on that....
seems a stroker is a clean way to get performance with not a lot of work and it still stays mostly all porsche except for the crank and rods.
It may seem that way, but when you factor everything into the equation, on a nominal basis, the forced induction setup will be ahead. However, we are all entitled to our opinions.. With that said, fact is still fact, and science is still science...
I have yet to see a 928 stroker dyno output's "area under the curve" exceed a properly prepared 928 forced induction dyno of the same with a similar displacement engine.... Not just peak, as I don't care about the peak... I want to see the "area under the curve"..
Hey MK, sorry, but some of us just have to push the envelope, and that involves some things that others may not find palletable such as spending a small fortune on engineering a solution to the problem of blowby that happens when you have blowby issues. Again, not all 928's have this, and it depends on the condition and load of the engine as you surely know!
these are street cars, fix them up, put on suspension , wheels and tires and make them look as they should, but stay away from the engine, unless you are stroking it. (personal opinion).
Have to disagree with this, as you can double the power output of the engine with forced induction and only place a 5% increased load on the rotating assembley, not to mention that the soft pressure reduces the load at certain stages using forced induction..
Compared to increasing the piston speed from which puts and incredible amount of stress on the rotating assembley. There is also increased stress on the rotating assembley with piston speed compared to forced induction due to the way the combustion cycle happens.. Anyway, too much to explain in detail here.. As an engineer with access to all those formulas, I am sure you can calculate the respective loads on the assembley yourself.. However, when accounting for the load of forced induction, don't forget that the rods won't fail in compression, but in tension, and this is minimized in forced induction vs normally aspirated.....
remember ive beat the snot of these cars for over 130 races, 15 years of racing and have NO issues with the car and its stock components (sans the headers and racing exhaust i use because its a race car). its an amazing vehicle. no one has done what ive done as far as reliability and performance with any other car out there. Porsche really made a gem with the 928.
the supercharger, turbo efforts seem to be just a lot of time and money for limited gain.
What's limited for you may not be the case with others, I think the Kuhn setup is a really good example of a very powerful setup that is very well done, and with 800 RWHP, it is pretty good value for $$$... To go that fast, you can basically get an S4 in great shape for $15K, and add another $20 K in mods, and drive your hearts content, and beat any stroker in acceleration and top speed. Considering a stroker motor is about $35K and puts out way less than 800 at the tires, and the available torque across the powerband is exceptional in the turbo car, the turbo car is a screaming deal.
I say this is without considering the increased stroke on a stroker will increase the wear on the rings from the extra travel in stroke, and am also not counting piston speed and increase load on the rod cap when it yanks the piston from TDC on the intake cycle...
Granted they are both works of art, but one produces a lot more power for the same $$$$.. Value for $$$ is very easy to calculate in that example..
In addition, because I am having my system CFD analyzed, does that make it less of a value to me? If you say 'yes', then that is only your opinion, not my value system.. And that's fine, but again only your opinion...
The same can be said for shifting to a full sequential ECU with COP, and other control and or engineering parameters.. Is it less value to use a better ECU instead of the LH...??
What about the guys that run the ORR, or the Texas mile, or the Mojave mile... Is it less beneficial to them to do all they do, when pretty much anyone can fly to Germany, rent a mid size turbo diesel from Audi/BMW and go 250 kmH all day long using less fuel than a gas car on the events in the USA, and travel faster for longer for less money, should we all fly to europe and not use our cars in the US events....?? I kind of doubt that any of those people will agree with you on that....
seems a stroker is a clean way to get performance with not a lot of work and it still stays mostly all porsche except for the crank and rods.
It may seem that way, but when you factor everything into the equation, on a nominal basis, the forced induction setup will be ahead. However, we are all entitled to our opinions.. With that said, fact is still fact, and science is still science...
I have yet to see a 928 stroker dyno output's "area under the curve" exceed a properly prepared 928 forced induction dyno of the same with a similar displacement engine.... Not just peak, as I don't care about the peak... I want to see the "area under the curve"..
Robot guy, don't mean to steal your thread.......
Tuomo has a good point with the valved tubes and a PV200..
I am running a GZ Vacuum pump and a PV400, and. So far, so good, the PV400 is doing its job extremely well. All clean after 1000 miles of all sorts of driving in heat, cold, hills etc.. (Don't use a PV200 with the vac pump, unless you have a really underdrive pulley, as the PV200 will vent the oil from the pressure side of the vac pump.. A PV400 will not do this at a .65 ratio of vac pulley to crank pulley, and neither will you overdrive the vac pump.... very important..)
However, I have not yet tested the setup with the compressor (SC) attached so it won't be fair to comment on that even if in theory it is similar to the effect of a dry sump as it evacs the gases and separates the oil and air and filters the air while keeping a vacuum in the crankcase so it will not "burp" from the blowby while promoting ring seal to lessen the blowby in the chamber. (It's all related...) I'll be reporting on the engine with the SC once I finish the install sometime this century..
Hope that helps with ideas as to what is possible to fix the blowby issue...
Best,
09-10-2013, 11:48 AM
#38
Developer
That was one of the things I considered when I bought my 79. -that it was pre-computer and emissions.
(also like burning regular gas and not having interference valves). With the 928 motorsports oil control kit installed I am not venting crankcase pressure to atmosphere. It still goes to the filter housing like all contemporaneous pre-81 cars. The louver plate below the separator merely deflects the majority of splash droplets and the rest drop at the T to the cam chamber. Gaseous fumes continue on back to the filter housing. It works and that is all I want.
(also like burning regular gas and not having interference valves). With the 928 motorsports oil control kit installed I am not venting crankcase pressure to atmosphere. It still goes to the filter housing like all contemporaneous pre-81 cars. The louver plate below the separator merely deflects the majority of splash droplets and the rest drop at the T to the cam chamber. Gaseous fumes continue on back to the filter housing. It works and that is all I want.
Bob,
Please be very certain that you aren't pressurizing the crankcase with a "vacuum" line that goes from intake manifold to crank-case. Check everywhere - we covered this in the installation manual for the kit, but I never know what the PO might have done.
Any remnant of the PCV system that used to evacuate the crankcase up into the intake and re-burn it will now go the other way on a supercharged car and pressurize the crankcase.
As to whether you want to run the crankcase vent to atmosphere with or without catch-can, or back into the intake on the suction side (AFTER the throttle body, not before it) that choice is up to you. I have customers who do either one and they both work well.
If street driving and having a little fun - running the fumes back into the motor and burning it is fine.
If racing - usually you don't want the lowered octane that re-burning a little crank oil will cause, and the racing organisation requires catch tanks on everything so you'll use a catch tank.
And then finally, compression check the motor. There is not amount of anything, not a louvered plate, a breather system, a catch can, or whatever that can make up for the amount of crnckase fumes that a scratched cylinder wall can produce.
Please get a hold of me if I can be of any assistance. Its my kit, I know it best. My contact information is below.