What are those lines on the speedometer between 30-40 mph?
And while I'm asking questions that I've always wondered about, what determines an engine's redline? And what is an approximate redline for a standard 1915 VS engines?
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What are those lines on the speedometer between 30-40 mph?
And while I'm asking questions that I've always wondered about, what determines an engine's redline? And what is an approximate redline for a standard 1915 VS engines?
And while I'm asking questions that I've always wondered about, what determines an engine's redline? And what is an approximate redline for a standard 1915 VS engines?
The speedo lines are suggested gear changes. Redline should really be determined by the engine builder, since he/she knows what parts were used, and how stout the engine is. Safe bet for a 1915 is 6000 rpm. Higher redline = big money as more bulletproof parts are used, tolerances will be closer, machining will be more careful, etc. For our street uses, a redline that approaches 8000 may be a waste of money, since that kind of engine is more suited to the track.
As I best recall the max rpm from VW was 4500 rpm, and I think the lines on the standard speedos refer to that, IIRC the recommended shift rpm was 3500. None of us adhere to that planned 4500rpm limit, but it does speak to VW's design intentions. While there are "VW engines" that crank out 8,000 rpms or more, very little of the engine remains VW (if any). Also, many of those engines are rebuilt weekly or several times a year, or after every blow up etc...but back to the basic VW engine...at higher rpms (6500-7000)the stock oiling system does strange things...the oil will develop bubbles in it from frothing and cavitation, 1/2 or more of the engines oil will be pushed into the left hand valve cover and pushrod tubes, oil pressure drops like a rock, oil is pushed into the breathers or out of the front of the case, rod bearings and main bearings start to go away in very short order etc.
We do a number of things to counteract these problems, such as add additional sumps, bigger oil pumps, full flow the cases, add coolers and remote filters, counterbalance the cranks, balance the entire engine, put breather tubes on the valve covers, maybe add something like and Accusump, on and on..
A lot of us never dyno our engines so we usually depend on the seat of the pants dyno....but, most of our engines develop max hp below 6000 rpm. That alone suggests that running over 5500-6000 rpm is an effort in futility...and experience suggests you are doing damage to your engine and not really gaining anything....even on extensively modified engines it would seem advisable to shift at the max hp point as can be seen on a dyno sheet....
We do a number of things to counteract these problems, such as add additional sumps, bigger oil pumps, full flow the cases, add coolers and remote filters, counterbalance the cranks, balance the entire engine, put breather tubes on the valve covers, maybe add something like and Accusump, on and on..
A lot of us never dyno our engines so we usually depend on the seat of the pants dyno....but, most of our engines develop max hp below 6000 rpm. That alone suggests that running over 5500-6000 rpm is an effort in futility...and experience suggests you are doing damage to your engine and not really gaining anything....even on extensively modified engines it would seem advisable to shift at the max hp point as can be seen on a dyno sheet....
Tmpus- ..."1/2 or more of the engines oil will be pushed into the left hand valve cover and pushrod tubes"... Is this a result of crank rotation-ie, a "windage" condition?
Thanks, SS
Thanks, SS
An engine's redline is determined by the combination of parts in it-camshaft, intake (heads and carbs) and exhaust. Size has nothing to do with it. As was previously alluded to, revving a motor constantly to 6000 rpm when peak hp (or redline) is at 5000 or 5500 rpm is foolish and will eventually break parts. Conversely, a motor that makes power to 6500 or 7000rpm but never sees more than 5000rpm is kind of a waste.
Unless the motor is some super high strung 8000rpm beast, the stock shift points (or a little more) work well for toddling around in traffic. But when the road opens up...(where's the grinning devil icon when you need it?)
Unless the motor is some super high strung 8000rpm beast, the stock shift points (or a little more) work well for toddling around in traffic. But when the road opens up...(where's the grinning devil icon when you need it?)
The lines on a VW speedometer do indeed indicate suggested shift points. They are 1, 2 and 3 tick marks at approximately 15, 30 and 45 mph.
The lines on a 356 speedometer are different. They are a band of lines between about 25 mph and 40 mph. When I investigated these one explanation was that this band represented the range of appropriate speeds within German cities.
I don't know how you would use or interpret this band to guide your shifting.
The lines on a 356 speedometer are different. They are a band of lines between about 25 mph and 40 mph. When I investigated these one explanation was that this band represented the range of appropriate speeds within German cities.
I don't know how you would use or interpret this band to guide your shifting.
Lines?...Lines??...We don't need no steenking lines!
~WB
~WB
Seems that I read that the definition of red line was when the valves
stopped opening and closing---is this called "valve float?.
Someone disabuse me if I'm wrong.
stopped opening and closing---is this called "valve float?.
Someone disabuse me if I'm wrong.
The valves can't stop opening because there is solid mechanical push behind them. However, the only thing making them close are the valve springs. At high enough RPM, the valve springs don't pull them closed fast enough, so you get a bunch of leakage.
At least that's what I THINK it means.
At least that's what I THINK it means.
Jack, Lane-
A piston engine converts a lot of reciprocating motion to rotational motion-- there's a lot of things going up and down inside your engine at a pretty rapid rate. "Valve float" is when the inertia of the valve-train opening and closing overcomes the ability of the valve-springs to control that motion.
Your engine's valves open and close once every two crankshaft revolutions. At 7000 RPM, each valve is opening and closing just over 58 time a second: that's just about the same rate that electrical current in your house oscillates between peaks. At that RPM, your valves are a medium-high pitched buzzer. The valve-springs need to keep snapping the valves shut. When they lose that ability-- the valves just stay off the seats, or continue accelerating past the nose of the cam-shaft lobe, and lose contact with the tip of the rocker arms. When this happens, things are no longer tight in the camshaft/lifter, or lifter/pushrod, or pushrod/rocker-arm, or rocker-arm/valve-tip junction. The valves are no longer under the control of the camshaft and valve-springs-- they are "floating".
Chances are fair that the valves will tag the top of the pistons in this situation. Even if they don't it's awful on all of the parts.
"Red-line" is the upper limit of what all the parts inside the engine were designed to withstand. In some engines, the crankshaft wants to come apart. In other, it's the pistons or connecting rods. In others still-- it's when the valves float. Over-revving is pretty ugly.
It's best to "over-build" an engine, but a lot of guys cheap out and won't. Your engine was probably designed to give peak horsepower at something south of 6000 RPM, but also built to hold together to 7000 RPM or more. You never know when you'll miss a shift or something.
Hopefully, this clears it up for you.
A piston engine converts a lot of reciprocating motion to rotational motion-- there's a lot of things going up and down inside your engine at a pretty rapid rate. "Valve float" is when the inertia of the valve-train opening and closing overcomes the ability of the valve-springs to control that motion.
Your engine's valves open and close once every two crankshaft revolutions. At 7000 RPM, each valve is opening and closing just over 58 time a second: that's just about the same rate that electrical current in your house oscillates between peaks. At that RPM, your valves are a medium-high pitched buzzer. The valve-springs need to keep snapping the valves shut. When they lose that ability-- the valves just stay off the seats, or continue accelerating past the nose of the cam-shaft lobe, and lose contact with the tip of the rocker arms. When this happens, things are no longer tight in the camshaft/lifter, or lifter/pushrod, or pushrod/rocker-arm, or rocker-arm/valve-tip junction. The valves are no longer under the control of the camshaft and valve-springs-- they are "floating".
Chances are fair that the valves will tag the top of the pistons in this situation. Even if they don't it's awful on all of the parts.
"Red-line" is the upper limit of what all the parts inside the engine were designed to withstand. In some engines, the crankshaft wants to come apart. In other, it's the pistons or connecting rods. In others still-- it's when the valves float. Over-revving is pretty ugly.
It's best to "over-build" an engine, but a lot of guys cheap out and won't. Your engine was probably designed to give peak horsepower at something south of 6000 RPM, but also built to hold together to 7000 RPM or more. You never know when you'll miss a shift or something.
Hopefully, this clears it up for you.
Tmpus- ..."1/2 or more of the engines oil will be pushed into the left hand valve cover and pushrod tubes"... Is this a result of crank rotation-ie, a "windage" condition?
Thanks, SS
I am of the opinion that windage is one of several major problems that comes into play above 6000 rpm. However, there is little agreement amongst experts, both real and self-proclaimed, on what the real problems are, or better yet, how to solve the problems.
The symptoms I saw on more than one engine include dropping oil pressure substantially above 6000 rpm's best case, or worst case blown engine when rpm's went well over 6k. A lot of engines go there, but unless you have done a lot of enhancements to oil management you risk blowing the engine every time. If you have doubts I recommend fitting an accurate oil pressure gauge where you can watch it along with your tach. It is very discomforting to watch 70 psi on the gauge at 6k rpm drop to 20 psi or less at 7k. In my case I went to oil shed on the crank and rods and inside the pistons, oversized breathers and hoses, dry sump, Autocrafter 2 stage dry sump pump, with a Accusump 2 quart backup. It works, oil pressure remains steady upwards of 7500 rpm. But, since my max torque and max hp both occur under 6000 rpm, there is no need to over rev it, ever.
Just for bragging rights, I am running Shuebeck ceramic lifters, Pauter roller tip roller bearing ratio rockers, very big valves in very big ported heads, 9:1 CR, dual Chevy valve springs, forged counterweighted balanced crank, 5.7" H rods, Chevy rod bearings, a complete cryogenics treatment of moving parts, ceramic coatings of combustion chambers, exhaust valves, and piston tops, graphite skirt coating on JE forged pistons, Polydyne coatings on bearings. Nickasil cylinders, CB high deck case, and some other stuff...it is a street engine, believe it or not.....runs pretty well. Very hi torque from 500rpm up through 5500......no peaks and valleys....but that engine has little to do with the OP regarding a docile 1915....I would make every effort to keep that engine under 6k....but that's just me...
Thanks, SS
I am of the opinion that windage is one of several major problems that comes into play above 6000 rpm. However, there is little agreement amongst experts, both real and self-proclaimed, on what the real problems are, or better yet, how to solve the problems.
The symptoms I saw on more than one engine include dropping oil pressure substantially above 6000 rpm's best case, or worst case blown engine when rpm's went well over 6k. A lot of engines go there, but unless you have done a lot of enhancements to oil management you risk blowing the engine every time. If you have doubts I recommend fitting an accurate oil pressure gauge where you can watch it along with your tach. It is very discomforting to watch 70 psi on the gauge at 6k rpm drop to 20 psi or less at 7k. In my case I went to oil shed on the crank and rods and inside the pistons, oversized breathers and hoses, dry sump, Autocrafter 2 stage dry sump pump, with a Accusump 2 quart backup. It works, oil pressure remains steady upwards of 7500 rpm. But, since my max torque and max hp both occur under 6000 rpm, there is no need to over rev it, ever.
Just for bragging rights, I am running Shuebeck ceramic lifters, Pauter roller tip roller bearing ratio rockers, very big valves in very big ported heads, 9:1 CR, dual Chevy valve springs, forged counterweighted balanced crank, 5.7" H rods, Chevy rod bearings, a complete cryogenics treatment of moving parts, ceramic coatings of combustion chambers, exhaust valves, and piston tops, graphite skirt coating on JE forged pistons, Polydyne coatings on bearings. Nickasil cylinders, CB high deck case, and some other stuff...it is a street engine, believe it or not.....runs pretty well. Very hi torque from 500rpm up through 5500......no peaks and valleys....but that engine has little to do with the OP regarding a docile 1915....I would make every effort to keep that engine under 6k....but that's just me...
tmpusfugit-
I've got about 2/3 of what you have- but no dry sump.... yet.
I'm still trying to figure out how to get that done with the A1 sidewinder. I'm running a windage tray, windage pushrod tubes, and a 2 qt accu-sump.
I've got a breather box with over 2 gallons of capacity, and vents from both valve-covers, a breather tower, and the fuel-pump block-off. I added 2 12AN drains from the 3/4 valve-cover back to the sump, but I'm afraid that without further oil system modification it's just masking the real issue.
What the engine needs is the Bob Hoover mods, the elimination of the stupid oil bypass system(s), and a dry-sump pump.
Totally off the point, but what are you running for a cam in that engine?
I've got about 2/3 of what you have- but no dry sump.... yet.
I'm still trying to figure out how to get that done with the A1 sidewinder. I'm running a windage tray, windage pushrod tubes, and a 2 qt accu-sump.
I've got a breather box with over 2 gallons of capacity, and vents from both valve-covers, a breather tower, and the fuel-pump block-off. I added 2 12AN drains from the 3/4 valve-cover back to the sump, but I'm afraid that without further oil system modification it's just masking the real issue.
What the engine needs is the Bob Hoover mods, the elimination of the stupid oil bypass system(s), and a dry-sump pump.
Totally off the point, but what are you running for a cam in that engine?
Also, I followed everything except for "I went to oil shed on the crank and rods"
What is that?
Gn
What is that?
Gn
Stan,
I am running a fairly mild cam, a WebCam 86A. It seems to work well with the Competition Eliminator heads and Weber 48's with the 1.4 ratio rockers. I am planning to do FI and MegaSpark crank fired ignition as soon as I get this back on the road with its current MSD.
While the drysump concept has worked well in my Spyder, it is difficult to find enough space in a Speedster (my old Spyder was easier) to put a sufficently sized oil tank. We should talk when you move forward with this....the tank has to be mounted low in the chassis as the contents of the tank will fill up the sump on the engine when shut off. Don't ask me how I discovered this...but a 3 or 4 quart oil spill in the middle of the floor, given a couple of days to spread out, makes a nasty mess.....the oil will fill the sump until it over flows the dipstick tube, and a great deal of my system was a lot higher in the chassis than the engine sump. I built a tank out of 5.5" aluminum tubing which fits in the passenger side wheel well, but I am certain it is too low in capacity for my car right now, which uses upwards of 12 quarts in the entire system. I think from an engineering concept I will need a 2 gallon tank, and I am not close (figure 3-4 quarts of oil in the cooling circuit 1 quart in the filtering circuit, the rest in the tank and or engine sump and oil thermostat circuit some of the time) large dual oil coolers mounted in the front of the car....also 914 oil cooler in the DTM fan shroud, most likely overkill but the 914 cooler is not nearly enough in Houston summer and a bit of driving fun...
86 A spec;
exhaust .430" 68 degrees after TDC
intake .215 19 degrees BTC
.213 12 degrees before TDC
I am running a fairly mild cam, a WebCam 86A. It seems to work well with the Competition Eliminator heads and Weber 48's with the 1.4 ratio rockers. I am planning to do FI and MegaSpark crank fired ignition as soon as I get this back on the road with its current MSD.
While the drysump concept has worked well in my Spyder, it is difficult to find enough space in a Speedster (my old Spyder was easier) to put a sufficently sized oil tank. We should talk when you move forward with this....the tank has to be mounted low in the chassis as the contents of the tank will fill up the sump on the engine when shut off. Don't ask me how I discovered this...but a 3 or 4 quart oil spill in the middle of the floor, given a couple of days to spread out, makes a nasty mess.....the oil will fill the sump until it over flows the dipstick tube, and a great deal of my system was a lot higher in the chassis than the engine sump. I built a tank out of 5.5" aluminum tubing which fits in the passenger side wheel well, but I am certain it is too low in capacity for my car right now, which uses upwards of 12 quarts in the entire system. I think from an engineering concept I will need a 2 gallon tank, and I am not close (figure 3-4 quarts of oil in the cooling circuit 1 quart in the filtering circuit, the rest in the tank and or engine sump and oil thermostat circuit some of the time) large dual oil coolers mounted in the front of the car....also 914 oil cooler in the DTM fan shroud, most likely overkill but the 914 cooler is not nearly enough in Houston summer and a bit of driving fun...
86 A spec;
exhaust .430" 68 degrees after TDC
intake .215 19 degrees BTC
.213 12 degrees before TDC
Gordon,
Oil Shed is a coating that helps mechanical parts shed oil faster http://www.performanceandperfection.com/coatings.html Does it work? Don't know, but both NASCAR and F1 use similar coating technology and claim several hp gains in their engines....but they do run much higher rpms than us....F1 in particular...I was interested to see if it would affect the oil behavior in a positive fashion in my engine. Of course now I have no real way to measure anything....no before and after dyno.....which could have told me something...It was not very expensive, the rods, crank throw, insides of pistons, and inside of the case were all under $100 IIRC. I had it done by the same company that did the ceramic coatings and the Polydyne bearing treatments.....so it was all one bill, and that was under $500.
Regards,
Jim
Oil Shed is a coating that helps mechanical parts shed oil faster http://www.performanceandperfection.com/coatings.html Does it work? Don't know, but both NASCAR and F1 use similar coating technology and claim several hp gains in their engines....but they do run much higher rpms than us....F1 in particular...I was interested to see if it would affect the oil behavior in a positive fashion in my engine. Of course now I have no real way to measure anything....no before and after dyno.....which could have told me something...It was not very expensive, the rods, crank throw, insides of pistons, and inside of the case were all under $100 IIRC. I had it done by the same company that did the ceramic coatings and the Polydyne bearing treatments.....so it was all one bill, and that was under $500.
Regards,
Jim
Jim-
Yeah, I already considered where to put the sump, and the fact that it would need to be lower than the level of the normal running level of the engine's sump. I'm sure I'd need to fabricate one from AL, but that was going to be a project done the same time I relocate my fuel tank to the nose of the car.
I'm running a single 96 plate cooler in addition to the DTM, so my capacity is a bit less than yours, but I figure it'll still need to be at least 2 gal.
My issue is the pump itself. An Autocraft hits my header collector. A CB is inadequately sized (21 mm pressure side) for what I'd like to do with piston squirters. The world could really use a shorter 2 stage dry sump pump with decently sized gears.
Yeah, I already considered where to put the sump, and the fact that it would need to be lower than the level of the normal running level of the engine's sump. I'm sure I'd need to fabricate one from AL, but that was going to be a project done the same time I relocate my fuel tank to the nose of the car.
I'm running a single 96 plate cooler in addition to the DTM, so my capacity is a bit less than yours, but I figure it'll still need to be at least 2 gal.
My issue is the pump itself. An Autocraft hits my header collector. A CB is inadequately sized (21 mm pressure side) for what I'd like to do with piston squirters. The world could really use a shorter 2 stage dry sump pump with decently sized gears.
Fortunately my headers clear the Autocraft 2 stage pump...please excuse the primer'ed body. Still an exercise in hopefully progress, awaiting a new transmission right now....there is a baffle in the short pipe, but it is pretty loud, as you may well guess.
Stan, I do have a little used CB dry sump pump if you want it, but I found it to be lacking in the way you suggest....piston oilers huh? Had not pursued that...my head and cylinder temps work out well with the Nickasils and ceramic coatings, but that certainly is not a cheap solution...
The exhaust system is CSP 1 3/4" and does have a hideaway muffler that does not fit into the fender well. I need to do some reforming on it if I decide to use it.
Stan, I do have a little used CB dry sump pump if you want it, but I found it to be lacking in the way you suggest....piston oilers huh? Had not pursued that...my head and cylinder temps work out well with the Nickasils and ceramic coatings, but that certainly is not a cheap solution...
The exhaust system is CSP 1 3/4" and does have a hideaway muffler that does not fit into the fender well. I need to do some reforming on it if I decide to use it.
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I've got nickasil cylinders, and ceramic coatings in my heads. The sidewinder is 1-3/4" as well.
Too much= just enough.
Too much= just enough.
"I've got nickasil cylinders, and ceramic coatings in my heads. The sidewinder is 1-3/4" as well.
Too much= just enough. "
Stan,
Sounds about right to me....I am not aware of any of the other guys on here that have gone the nickasil and ceramic route other than the 2 of us. I am generally pleased with the overall results, I have about 10k miles on the engine. Other than some oil leaks that have been persistant over the life of the engine, (finally resolved, knock on wood) and those are the fault of the engine builder (me) I am happy. I have not dyno'ed it but weight measured against accelleration time run through the computer suggests I have over 200hp at the rear wheels, I have more hp than I have traction, but I still find myself wondering how much fun it could be with a turbo, or maybe a turbo Suby?
I could have had one outrageous Suby for what I have in this engine, suspect you have spent similar amounts...hindsight, and I do like what I have, but your "Too much= just enough" rings true to me....
Guess I am not likely to grow up soon....
Too much= just enough. "
Stan,
Sounds about right to me....I am not aware of any of the other guys on here that have gone the nickasil and ceramic route other than the 2 of us. I am generally pleased with the overall results, I have about 10k miles on the engine. Other than some oil leaks that have been persistant over the life of the engine, (finally resolved, knock on wood) and those are the fault of the engine builder (me) I am happy. I have not dyno'ed it but weight measured against accelleration time run through the computer suggests I have over 200hp at the rear wheels, I have more hp than I have traction, but I still find myself wondering how much fun it could be with a turbo, or maybe a turbo Suby?
I could have had one outrageous Suby for what I have in this engine, suspect you have spent similar amounts...hindsight, and I do like what I have, but your "Too much= just enough" rings true to me....
Guess I am not likely to grow up soon....