turbobitt
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I was stuck with this ring package due to rod length and stroke. I am using very low tension rings but oil control doesn't appear to be an issue.
Allan G.
Time to go Stage II!
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I was stuck with this ring package due to rod length and stroke. I am using very low tension rings but oil control doesn't appear to be an issue.
Allan G.
What weight oil are you using? I'll be running 25w-50, or straight 50w. The small oil rings are really good for controlling light weight oils.
Alky V6 said:
Oil control is less of a concern in a turbocharged engine that is not used primarily on the street at extended periods of vacuum. As you already stated the second ring acts as an oil control ring more than it seals compression. There is so much cylinder pressure through the entire 4 strokes that there is no possibility of oil being pulled into the cylinder while under power. Keeping windage down is probably more important in a turbocharged drag race engine for oil control when running the lowest tension smallest oil rings out there. I dont have any windage data but I'm sure it's out there. I'd bet any naturally aspirated racer that is required to use a certain carb that creates vacuum under power has a lot of oil control and windage data.
I would agree with you, except in the case where excessive crankcase pressure builds. Then oil control can be a concern. The trick is to not let excessive crankcase pressure build up in the first place. Make sure the bottom end is properly vented. In the case of a TA block, where the block comes with the lifter valley completely blocked off from the bottom end, and only one small hole is available for the bottom end to vent to the lifter valley area through the front of the block and then the valve covers, the engine builder will need to provide addition lower end venting capacity, over and above what the block comes with out of the box.
turbobitt
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The reason I'm changing from the 3mm oil control set to the more standard 3/16" package is not because I was seeing traces of oil smoke in the exhaust or experiencing fouling of the spark plugs. That was never a problem, except for when I was experiencing over pressurization of the crankcase by the end of a run. I would get a pretty nasty puff of oil smoke when I got off the throttle. That problem was bandaided with the Stage I engine, and will be thoroughly corrected with this build.
What I did notice was whenever I would use the borescope to inspect the cylinders, the piston tops always appeared to have a wet oily appearance to them. I'm just curious to see if I can change that with hopefully better oil control. Or, was that residue from the topend lube I use with the methanol?
What I did notice was whenever I would use the borescope to inspect the cylinders, the piston tops always appeared to have a wet oily appearance to them. I'm just curious to see if I can change that with hopefully better oil control. Or, was that residue from the topend lube I use with the methanol?
278cikiller
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Like to ask Donnie! when will we see your car at the track with this new combo? I can't wait, You are over the top with this sh!t.
Chris Hogeland
TWISTED 6 RACING
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This is the thing on spring psi. Get what you need for open psi and what ever you have on the seat is what it is. Most of the stage heads I set up will have at least 350 on the seat. I like .60 to .100 on coil bind. That way you are using the spring. When the ex valve is trying to close at 40psi of boost you need A lot more spring PSI than you think.
Probably around the end of the year, if not sooner.
How much exhaust back pressure are you assuming I'll have with 40 psi boost?
My plan is to have much less exhaust backpressure than what many would consider the norm.
Here are some ring gap guide lines from manely, notice 2nd ring is smaller then top ring............seems like all different info on this topic.
http://www.manleyperformance.com/dl/tech/piston-rings.pdf
http://www.manleyperformance.com/dl/tech/piston-rings.pdf
As I've explained to you before, I'm sure when you see a ring gap spec where the second ring is tighter than the top ring, the assumption is the top ring will see more heat than the second ring and the top ring gap will end up tighter than the second ring under actual operation. One of the duties of the top ring is to transfer the majority of combustion heat from the piston to the cylinder wall, so it will see more heat loading than the second ring, and because of that more expansion.
What are you plans here 2nd ring bigger or same or smaller?
I'll see what they recommend with the ring set.
turbobitt
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Don,
What made you go with a dual pattern camshaft ? Was it the Cam manufacture or yourself ?
Allan G.
It appears the Hellfire ring is available in all the popular ring thicknesses.
Go to this link and open the Speed Pro catalog. Go to pages 236 and 237 of the catalog for information about the rings and ring fitting.
http://www.fme-cat.com/PerfDigitalCatalogs.aspx
It looks like I'll be going with the same gap on both the top and second rings. I'll have to check my past records to see what gaps I've used in the past, but I think I'll be starting with a .022-.024" gap. Possibly closing it up to .020" depending on what I've gotten away with in the past. But then, I will be increasing the performance with this build, so maybe I'll just start out with what I've used in the past and adjust from there.
Go to this link and open the Speed Pro catalog. Go to pages 236 and 237 of the catalog for information about the rings and ring fitting.
http://www.fme-cat.com/PerfDigitalCatalogs.aspx
It looks like I'll be going with the same gap on both the top and second rings. I'll have to check my past records to see what gaps I've used in the past, but I think I'll be starting with a .022-.024" gap. Possibly closing it up to .020" depending on what I've gotten away with in the past. But then, I will be increasing the performance with this build, so maybe I'll just start out with what I've used in the past and adjust from there.
It was work that I did with the sim that led me to go with a dual pattern. Then Crower went with what I presented (engine and cam specs, power and rpm goals) and made further recommendations. I took their recommendations and ran it in the sim and liked the changes.
What I really liked was that Dave went even more radical with the specs than I did. A man after my own heart.
Crower also uses a number of sims. He wouldn't tell me what they were, though.
This is a latest test with the engine sim using a 2.40" turbine nozzle diameter, which happens to match real world results fairly closely. The window shows the pressure trails for the exhaust system, the intake system, and the cylinder as the program calculates the 9,250 rpm column. Notice at the point where the exhaust valve is closing (EC) just past TDC, the exhaust pressure is the lowest of the three pressure values. The cylinder pressure is above that. Then the intake above the cylinder pressure.
If I decrease the turbine nozzle diameter to 2.00", the pressure traces end up being about equal pressures for the exhaust, intake and cylinder at the same 9,250 rpm. A true 1:1 exhbp to intbp ratio.
There is also an increase in peak hp, since the smaller turbine nozzle diameter is able to push this turbo to a higher boost level of around 48-49 psi. The increase in power from 40-41 psi boost and the better than 1:1 intbp to exhbp ratio, to 48-49 psi boost with an equal 1:1 exhbp to intbp ratio, is only about 30 hp. Other parameters are also struggling at this high of a boost level.
This is just under a 2% increase in horspower from the better than 1:1 exhbp to intbp at 40 psi boost, to an equal 1:1 exhbp to intbp ratio at 48 psi boost.
If I decrease the turbine nozzle diameter to 1.80", peak power begins to drop due to rising exhaust back pressure. The pressure traces also begin to show the exhaust pressure at the time of the exhaust valve closing event to be above cylinder and intake pressures, which brings problems such as exhaust reversion and the need to adjust cam timing to compensate for it, and different valve spring pressure requirements (higher seat spring pressures) into play.
There is also an increase in peak hp, since the smaller turbine nozzle diameter is able to push this turbo to a higher boost level of around 48-49 psi. The increase in power from 40-41 psi boost and the better than 1:1 intbp to exhbp ratio, to 48-49 psi boost with an equal 1:1 exhbp to intbp ratio, is only about 30 hp. Other parameters are also struggling at this high of a boost level.
This is just under a 2% increase in horspower from the better than 1:1 exhbp to intbp at 40 psi boost, to an equal 1:1 exhbp to intbp ratio at 48 psi boost.
If I decrease the turbine nozzle diameter to 1.80", peak power begins to drop due to rising exhaust back pressure. The pressure traces also begin to show the exhaust pressure at the time of the exhaust valve closing event to be above cylinder and intake pressures, which brings problems such as exhaust reversion and the need to adjust cam timing to compensate for it, and different valve spring pressure requirements (higher seat spring pressures) into play.
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