Flat Plane Crank LS1
- Thread starter Troymx576
- Start date
Geoff? Do not take this the wrong way, but how do you know that? Have you built one? Or more Internet rumor? My crank builder has built a lot of flat plane crack v8's and if you use a fully counterweighted crank he said no issues at all. He did say for a race engine he could build a crank half the weight that would vibrate. I think it is how you build it. I think this is yet another myth out there. We will see.
On the reverse the heads. So new pistons, custom exhaust, some crazy intakes and two of them, new fuel lines ect to Feed, rewire for different locations. Then a custom intakes? With castings and machine work we are probably talking 5k or more for a bare set. Then all the head work and finishing. That engine would cost way more in the end.
If, I should say when since I am confident, that the engine runs and runs good with the crazy sound then we will see who else goes crazy for it. Fun.
On the exh I will check them out and see if the make a small muffler we will need. I might be trying many different ones when this is all done to get what I want. I also see the Ferrari v8's use a 4-1 design header and that would make it simplier so I will start there.
On the reverse the heads. So new pistons, custom exhaust, some crazy intakes and two of them, new fuel lines ect to Feed, rewire for different locations. Then a custom intakes? With castings and machine work we are probably talking 5k or more for a bare set. Then all the head work and finishing. That engine would cost way more in the end.
If, I should say when since I am confident, that the engine runs and runs good with the crazy sound then we will see who else goes crazy for it. Fun.
On the exh I will check them out and see if the make a small muffler we will need. I might be trying many different ones when this is all done to get what I want. I also see the Ferrari v8's use a 4-1 design header and that would make it simplier so I will start there.
Look at this post regarding engine sound. Apparently it is by some guy that either has and F40 or loves F40's don't know. But he says at the end that he made a flat plane 327 v8 for stock car racing and that his car was outlawed because it was so loud that the fans could not hear the announcer. Here is the quote:
"Besides the engine, there are a number of accessories which produce noise in the engine compartment--such as the alternator, AC compressor, engine cooling fan, etc. These soundwave components which vary with the engine combustion noise since they are driven by belts connected to pulleys which are being rotated by the engine crankshaft. Depending on the pulley ratios, these they may or may not produce a noise that is a harmonic of the engine. There's a few other components of noise as well, ie. the noise of the rubber tires rolling over asphalt, the air being disturbed as the car moves forward (or backward), and the gears in the transmission meshing and unmeshing. If the gears are straight-cut, as in reverse, you get the very noticeable whine. In addition to these major components of engine noise, some noise results from the turbulent air flow over accessories such as the radiator, radiator fans, and alternator. Finally, you can get lots of variation from the same noise source if the noise(s) reach you after being reflected off walls or other surfaces.
Focusing on the engine note, the combustion of fuel in the engine cylinders is the major source of this noise. This combustion is an explosion like a gunshot, basically a sharp, flat sound or report. The exact nature of this report (how it sounds) is determined by the frequency, separation, and intensity of the explosions. These are determined by the cam profile, the size of the cylinder, the shape of the top of the piston, the compression ratio, the compression rate, the shape and location and position of the intake and exhaust valves, and the engine materials and their thicknesses. Additionally, how the explosion soundwaves reverberate through all the other structures in the engine bay, and the paths they follow before reaching your ears also influence the sound you hear or bass notes that you feel.
Because there's multiple explosions happening each second, the noise pulses combine into a continuous burble or rumble or drone. The combustion(s) produces pressure pulses at a rate proportional to engine speed (the "revs"). In a four stroke engine, combustion in each cylinder occurs once every two engine revolutions, i.e. there are four pressure pulses per crankshaft revolution in an eight cylinder engine. As the revolutions increase, the frequency increases (more explosions per second) and you get the higher pitch sound or waaaaah, ie. the characteristic Ferrari wail.
Additionally, noise is generated by the turbulent air flow from the air intake and exhaust systems. Engineers vary the diameter and length of the intake and exhaust systems so that standing wavesforms are created--this helps move the air through quickly, resulting in more air intake or better exhaust scavenging--this is how you get the term "tuned intake" and "tuned exhaust." These standing waves, or constant pulses, also contribute sound energy and form part of the engine's characteristic noise.
The flat plane crank shaft is the key component. This allows for each bank to A) be in perfect ballance (primary) which allows B) each bank to have equal intervals of breathing which allows C) using harmonics in the pulse streams (intake and exhaust) to create more power.
But Ferrari does not stop there:
The intakes are short, straight, and direct, but the key component here is the throttles sitting in the exact center of the intake (plus velocity stack). This point has what is knonw as a pole in harmonic analysis terms. And having the throttle is the exact center of the intake allows the throttle to modulate the airflow without disrupting the harmonics. The single/dual throttle bodies of typical carrs cannot do this.
To make use of the harmonic energy in the intake tracks, each bank is isolated in a helmholtz resonator that preserves the waves of the intake systems so that when a valve is ready to open, a high pressure wave is arriving at the back side of the valve just when the valve is set to open.
Then on the exhaust side, each header is perfectly tuned to the RPM band where the engine make best power. In the power band, the header is tuned to have a negative wave arrive at the back side of the exhaust valve while it is still open. This negative pressure wave crosses the cylinder and arrives at the front side of the intake valves just as they open. The combined effects of the intake and exhaust resonance pulls fresh mixture into the cylinder even before the cylinder begins its downward journey.
Finally, the cam is selected to work with the header and increase the wave effects in the intake system.
In effect, its the whole package!
But without the flat plane crank, about 50% of this harmonic energy could not be utilized because the pusle intervals would not line up in a harmonic way.
I once had a 327 Chev V8 built with a flat crank for stock car racing and after 2 races they outlawed my car, not because it won races but because it was SO LOUD that the fans could not hear the track announcer!!"
I found this on Does Ferrari tune the sound of thier motors? - FerrariChat.com the poster is F40Lover.
Troy you might want to talk with this guy and see what his experience was.
"Besides the engine, there are a number of accessories which produce noise in the engine compartment--such as the alternator, AC compressor, engine cooling fan, etc. These soundwave components which vary with the engine combustion noise since they are driven by belts connected to pulleys which are being rotated by the engine crankshaft. Depending on the pulley ratios, these they may or may not produce a noise that is a harmonic of the engine. There's a few other components of noise as well, ie. the noise of the rubber tires rolling over asphalt, the air being disturbed as the car moves forward (or backward), and the gears in the transmission meshing and unmeshing. If the gears are straight-cut, as in reverse, you get the very noticeable whine. In addition to these major components of engine noise, some noise results from the turbulent air flow over accessories such as the radiator, radiator fans, and alternator. Finally, you can get lots of variation from the same noise source if the noise(s) reach you after being reflected off walls or other surfaces.
Focusing on the engine note, the combustion of fuel in the engine cylinders is the major source of this noise. This combustion is an explosion like a gunshot, basically a sharp, flat sound or report. The exact nature of this report (how it sounds) is determined by the frequency, separation, and intensity of the explosions. These are determined by the cam profile, the size of the cylinder, the shape of the top of the piston, the compression ratio, the compression rate, the shape and location and position of the intake and exhaust valves, and the engine materials and their thicknesses. Additionally, how the explosion soundwaves reverberate through all the other structures in the engine bay, and the paths they follow before reaching your ears also influence the sound you hear or bass notes that you feel.
Because there's multiple explosions happening each second, the noise pulses combine into a continuous burble or rumble or drone. The combustion(s) produces pressure pulses at a rate proportional to engine speed (the "revs"). In a four stroke engine, combustion in each cylinder occurs once every two engine revolutions, i.e. there are four pressure pulses per crankshaft revolution in an eight cylinder engine. As the revolutions increase, the frequency increases (more explosions per second) and you get the higher pitch sound or waaaaah, ie. the characteristic Ferrari wail.
Additionally, noise is generated by the turbulent air flow from the air intake and exhaust systems. Engineers vary the diameter and length of the intake and exhaust systems so that standing wavesforms are created--this helps move the air through quickly, resulting in more air intake or better exhaust scavenging--this is how you get the term "tuned intake" and "tuned exhaust." These standing waves, or constant pulses, also contribute sound energy and form part of the engine's characteristic noise.
The flat plane crank shaft is the key component. This allows for each bank to A) be in perfect ballance (primary) which allows B) each bank to have equal intervals of breathing which allows C) using harmonics in the pulse streams (intake and exhaust) to create more power.
But Ferrari does not stop there:
The intakes are short, straight, and direct, but the key component here is the throttles sitting in the exact center of the intake (plus velocity stack). This point has what is knonw as a pole in harmonic analysis terms. And having the throttle is the exact center of the intake allows the throttle to modulate the airflow without disrupting the harmonics. The single/dual throttle bodies of typical carrs cannot do this.
To make use of the harmonic energy in the intake tracks, each bank is isolated in a helmholtz resonator that preserves the waves of the intake systems so that when a valve is ready to open, a high pressure wave is arriving at the back side of the valve just when the valve is set to open.
Then on the exhaust side, each header is perfectly tuned to the RPM band where the engine make best power. In the power band, the header is tuned to have a negative wave arrive at the back side of the exhaust valve while it is still open. This negative pressure wave crosses the cylinder and arrives at the front side of the intake valves just as they open. The combined effects of the intake and exhaust resonance pulls fresh mixture into the cylinder even before the cylinder begins its downward journey.
Finally, the cam is selected to work with the header and increase the wave effects in the intake system.
In effect, its the whole package!
But without the flat plane crank, about 50% of this harmonic energy could not be utilized because the pusle intervals would not line up in a harmonic way.
I once had a 327 Chev V8 built with a flat crank for stock car racing and after 2 races they outlawed my car, not because it won races but because it was SO LOUD that the fans could not hear the track announcer!!"
I found this on Does Ferrari tune the sound of thier motors? - FerrariChat.com the poster is F40Lover.
Troy you might want to talk with this guy and see what his experience was.
Good read. I did read up a little bit on the exhaust and pulses so this adds to that. I will see about contacting him. At least it has been done. He could have just put a small muffler or something on it I would think. I guess no open exhaust for me. At least my engine will rev really high and have a smaller displacement so maybe the engine will have a higher pitch scream to it. This is good news.
On the F360 or F430 engine. As far as I know they have two plenums and two throttle bodies. They have velocity stacks inside each plenum. My plan is to copy the intake design and just use two LS1 throttle bodies.
On the F360 or F430 engine. As far as I know they have two plenums and two throttle bodies. They have velocity stacks inside each plenum. My plan is to copy the intake design and just use two LS1 throttle bodies.
In which case you might find that whilst these are expensive it may be cheaper to go with them than designing your own:
Products
Discussed briefly in this thread:
http://www.gt40s.com/forum/slc-clubhouse/38067-found-intake-exhaust-i-will-getting.html
Products
Discussed briefly in this thread:
http://www.gt40s.com/forum/slc-clubhouse/38067-found-intake-exhaust-i-will-getting.html
You'll never get to 8000 rpm using an intake with 12.5" runners. An intake properly tuned for high rpm will be critical to this project, and 12.5" is definitely not it.
That intake is way to long. With thos runners being that long that is a lower to mid rpm motor for sure.
Mine will be 5-5.5" long on the intake and then the head is 5.5" so total will be right in the 10" range. I am going to make my own intake myself as I can not afford a $5,000 intake, plus it will be a lot of fun to amke and be able to say I made my own. It will be CNC alum for the base flanges and flange into the intake, Carbon Fiber for the top portion and alum for the runners that I will press into forms that match the cylinder head and go to a velocity stack. I am not sure if I will do do forms, but I am thinking one nice smooth stack. We will see how it comes out when all done.
If there's one thing I learned when i was researching intakes it's that you better know what the f*k you're doing when building one - there's a lot that goes into the proper construction of one, and doing it improperly will just rape your engine.
Alex. Very true. There are a bunch of variables to consider. Runner diameter, size, shape, length, how it enters the plenum, plenum size and shape. Each variable can change the rest. I have two ideas on the intake and might make both and swap out when tuning on the dyno and also start out with a stock intake. Lots to test and tune, but me having dyno time is nice. I am thinking I might do the same with exhaust. 4-1 and 4-2-1 with different mufflers to see which sounds and works out best.
On another quick update. I am going to get custom Diamond pistons now. They will make them to the Hp and rpms I want in na form so the can be much lighter and use what is needed. Might be like 150 grams lighter per in the 350 range, use a 22mm pin the is shorter and in bound more plus different rings and sizes for less friction and high rpm function. So very cool and only a few hundred more than shelf. Plus I need like 10cc+ domed and this can get what I want.
On con rods I talked with Pauter and they can make custom lighter weight ones for it in the 550 gram range. I am also going to see if Carillo can make a light weight I beam one. So little things are professing and I am still learning every day.
On another quick update. I am going to get custom Diamond pistons now. They will make them to the Hp and rpms I want in na form so the can be much lighter and use what is needed. Might be like 150 grams lighter per in the 350 range, use a 22mm pin the is shorter and in bound more plus different rings and sizes for less friction and high rpm function. So very cool and only a few hundred more than shelf. Plus I need like 10cc+ domed and this can get what I want.
On con rods I talked with Pauter and they can make custom lighter weight ones for it in the 550 gram range. I am also going to see if Carillo can make a light weight I beam one. So little things are professing and I am still learning every day.
Ok, this may be a bit left field,, but.....
It looks like the design of intake manifolds do not take in consideration the firing order (at least the ones I have seen). Here is what I mean. If you look at the Carbon, the 4 runners for of the left go to the right bank, and on the right, they go to the left.
Am I wrong to think that intake pulses are just as important as exhaust pulses. Here is what I mean.
The Gt40's (as well as others of the time), messed with 180 degree headers because it allowed for better scavenging and evened up the exhaust pulses. If there was a cheap, easy, and less expensive way to to do it, I believe you would see a lot more of it because of the HP gains.
My question is. Why don't they design intake manifolds the same way? Cross over the intakes so there is no double pulse. Are you not starving a cylinder because of the double intake pulse? It would be pretty easy to design an equal length intake manifold that crossed over 2/4 and 3/5. This way your intake pulses (given a split design manifold), would be L,R,L,R,L,R and so on.
It looks like the design of intake manifolds do not take in consideration the firing order (at least the ones I have seen). Here is what I mean. If you look at the Carbon, the 4 runners for of the left go to the right bank, and on the right, they go to the left.
Am I wrong to think that intake pulses are just as important as exhaust pulses. Here is what I mean.
The Gt40's (as well as others of the time), messed with 180 degree headers because it allowed for better scavenging and evened up the exhaust pulses. If there was a cheap, easy, and less expensive way to to do it, I believe you would see a lot more of it because of the HP gains.
My question is. Why don't they design intake manifolds the same way? Cross over the intakes so there is no double pulse. Are you not starving a cylinder because of the double intake pulse? It would be pretty easy to design an equal length intake manifold that crossed over 2/4 and 3/5. This way your intake pulses (given a split design manifold), would be L,R,L,R,L,R and so on.
The reason is the same reason that you can easily blow out a candle, but you can't suck one out. There is some interference from one intake runner to another one nearby (but more often than not it is because of reversion flow during the overlap contaminating the charge air of the neighboring runner rather than the effects of forward air flow), but the effects just aren't significant enough to warrant building a much more complicated intake.
I decided on Rods now. Crower custom maxi lite 1 I beam. Very light and strong. They will be 500-505 grams when done. I am also using a 22mm top pin, with a very light piston should have less friction with the race bearings and more Hp. I will put that back into the program and also delete the power steering so my signature and aviator will change.
I would like to ask a couple of questions re: things I'm unsure about. If this motor is built for the street isn't there going to be an issue with the low mass of the reciprocating assembly, in that assuming a lightweight flywheel to complement the slimmed down crank assy, and a fairly hot cam, presumably the tick-over would have to be in the region of 1k rpm upwards to avoid stalling?
I only say this because I used to road race a Penske Camaro with 1st Generation 350 SBC. One of the major improvements I made for less bucks was to replace the "train wheel" flywheel with a lightweight aluminium version and triple plate AP Racing clutch. The difference in rev rate was very very noticeable, and engine braking vastly improved. The only downside (which wasn't really a downside for a track car) was that I had to keep the revs way up to avoid stalling and that also meant having a first gear that could cope too.
If you are planning a street track car, might this be an issue? I don't know, I'm just bench racing here but you are planning something fairly radical and as has been illustrated here, the changes do have significant knock on effects further down the line.
It's a pity there isn't a "street" version of the Hewland style that could enable quick ratio swap outs.
I'm also trying to get my head around a 180 degree crank with pushrods, as I would have thought a major benefit of the flat plane would be to exploit a much high rev range which might compromise valve spring longevity. But, it's an interesting project for sure.
I don't know Cliff why gave up on it after spending that kind of money, maybe he would enlighten us?
I only say this because I used to road race a Penske Camaro with 1st Generation 350 SBC. One of the major improvements I made for less bucks was to replace the "train wheel" flywheel with a lightweight aluminium version and triple plate AP Racing clutch. The difference in rev rate was very very noticeable, and engine braking vastly improved. The only downside (which wasn't really a downside for a track car) was that I had to keep the revs way up to avoid stalling and that also meant having a first gear that could cope too.
If you are planning a street track car, might this be an issue? I don't know, I'm just bench racing here but you are planning something fairly radical and as has been illustrated here, the changes do have significant knock on effects further down the line.
It's a pity there isn't a "street" version of the Hewland style that could enable quick ratio swap outs.
I'm also trying to get my head around a 180 degree crank with pushrods, as I would have thought a major benefit of the flat plane would be to exploit a much high rev range which might compromise valve spring longevity. But, it's an interesting project for sure.
I don't know Cliff why gave up on it after spending that kind of money, maybe he would enlighten us?
I too was wondering about that. It seems that the street Ferrari's idle fairly high as well, typically in the 900-1000 range? I use to have a Porsche 914-6 bumped to 2.7 liter carreta with dual webers and a hot early "S" cam and my tuner had to keep it idling at 1000 rpm (I know its not a flat plane). It appears that these flat plane motors are not like the typical v8 that can idle down in the 500-600 range.
Probably the same reason I gave up on my engine and took a loss - after a while it just isn't f*king worth the hassle or aggravation anymore.
I find it funny the desire to have a low idle in the 600 range. I have not had a car idle under 1,000 ever so that is normal to me. On the street driving I am very used to very low mass 4 cyl engines that needed help to go instead of torque. I think this will be much better than that. Also, the stock crank is 50+ and my flat plane will be like 45lbs. This should keep it very streetable and be heavy enough to make it not vibrate and be a smooth running engine.
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Can anyone tell me how much room I have above the engine to work with in making a custom intake up to the cover or bodywork? From looking at the F430 engine that is a really tall intake. I do not want that or need it that tall due to the cyl head runner length, but I can do a range of 4.5" to 6.5" runners on top of the head into the plenum and right about 6" is ideal. I am working on the plenum size and shape based on what I can fit.
Troy
Troy