Dusty Bradford
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- May 24, 2001
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Lol. This test was meant to prove the proper layout of a waste gate connection. Was it not?
Time to go Stage II!
- Thread starter Alky V6
- Start date
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Kinda, but nothing is wrong with 90 degrees if the gate is big enough, it maybe not the best location though. Is this not part of the debate?
Good grief. I'm sorry, guys. I guess I should have spelled it out. My mistake. I was using the wastegate connection to bring to light how the exhaust flow in the main tube can cause a pressure depression in the wastegate tube when the wastegate tube is oriented to the main exhaust tube in a less than optimum way.Now that we've proven that it does, let's move away from the WG, OK?
My main mission with bringing the WG into the argument was to then translate what we found with the WG tube to what is happening with the other primary tubes in a collector.
Let's imagine that the wastegate tube we were experimenting with, is now another primary exhaust tube. Let's also mount the tube so that it's parallel with other primary tubes. At the end of these primary tubes, let's add a collector. Are you guys following me now?
One of the primary tubes in this collector arrangement has this blast of exhaust gases shoot out into and through the collector. In fact, the blowdown through the exhaust port of that cylinder connected to that exhaust pipe is peaking in velocity and pressure just as the exhaust valve in another cylinder connected to that collector is closing and seating.
What is happening in the other primary tubes connected to this collector?
What is happening in the other primary tubes connected to this collector?
I guess im old school and like to see the numbers on a lighted board with a time slip to prove how good it works.All this means nothing without a slip to me but like i said im old and don't claim to understand anything but common sense.You need a slip to show us how well it works..Losts of boost always works for me LOL
That's right, Geno. The time slip will let us know if all this is worth a darn. That will be the final test.
The program must take into account the other cylinders in its calculations. When I tried switching to a twin turbo setup, which would separate the exhaust pressures mixing bank to bank, the exhaust pressure traces changed. Still not sure about it, though. Could be just the difference in exhaust backpressure caused by the different turbine housings. I'm going to contact the sim company and get an answer on this.
Sorry Donnie for not responding earlier, it looks like you not going to start making 20 psi boost until 5600 rpm with no wastegate?
The sim is generous with the boost curve. With the Stage I engine, boost ramp up was not as sharp as the sim is showing. 20 psi boost is about 237 kPa manifold pressure. The engine was reaching that manifold pressure by about 6400 rpm. This was with the wastegate clamped shut.
If you take that graph you linked to, draw a straight line from the point where the boost just starts to quickly climb, draw the line through the 20 psi/6400 rpm point, and then to end on the existing curve on the graph, that would be a more realistic example of what the Stage I boost climb rate was like. With the wastegate clamped shut.
Donnie, I do understand your setup is race only, but on my setup I would like to be at 30 psi boost by 4000 RPM max. With this new combo your going to have to run a monster of a converter, how else to do expect to run close to 9000 rpm at the end of the quarter?
With a lot of MPH?
30 psi by 4000 rpm. What sort of cylinder pressure do you think you'll have there?
Ok, maybe that is not possible, I won;t know until I spool it up maybe 5000 rpm seems more realistic. To reach 9000 rpm you will be travelling 200 mph with 5% slip approx with a 3.5 gear 28" tire
I'm estimating a 7.87 E.T (5.03 E.T./140 mph, 8000 rpm, 20% TC slip in the 1/8). About 174 mph and 8,700 rpm with 12% TC slippage at the end of the 1/4. ON A GOOD TRACK.
28.4 dia tire.
3.3% tire growth.
3.73 rear axle gear.
1% tire slip.
95% traction factor.
Safe cylinder pressure levels.
Assuming an optimistic hp level of 1,535 bhp.
Launch hp level: 880 bhp @ 6,000 rpm.
Conservative 8,000 rpm 1-2 and 2-3 shift points.
Part of an article, Tune Your Own Custom Made Header, from the June, 2009 issue of Turbo and High Tech Performance magazine. This part of the article pertains to using a log manifold versus a tuned exhaust system on a turbo engine.
"Log turbo manifold
Many debate the usefulness of simple log turbo manifolds versus a header combined with a turbo. It is true that a turbo motor can make lots of power with a log-type manifold. It is also true that a log manifold can spool faster than a tuned manifold. This is because a turbo is driven partly by heat energy and expansion of the hot exhaust gasses. The longer tubes in a tuned header tend to dissipate a lot of this heat energy before the turbo, which can result in more turbo lag. However, turbos can use the pulse energy for better breathing and to help spool the turbo faster as well.
In my experience, log manifolds and a properly engineered tuned manifold will have nearly the same boost onset rpm. The log manifold spools the turbo faster and more violently while the tuned manifold has a smoother, more gradual onset of boost that is more manageable and controllable with the throttle. The engine with a tuned manifold will be snappier off boost. A properly designed, tuned turbo manifold will have from 30-100 more horsepower than an untuned, or log manifold, at the same boost level. It's usually a good trade off. The lag and heat loss of a longer runner tuned turbo manifold can be minimized through the use of stainless steel in the manifolds construction. Stainless has poor thermal conductivity and keeps the heat in the pipes and thus transfers more heat to the turbine. By adding tricks to the manifold design like pulse conversion where the runners 180 degrees out of phase are matched with each other to let the turbine have evenly timed pulses hitting it, the lag can be reduced or even improved over a log manifold while retaining the advantages of a tuned system's good breathing. As an example in a 4-cylinder: you would pair cylinders 1 and 4 with 2 and 3, side-by-side right before the turbine. Doing this with a twin scroll turbine housing makes for a huge improvement in spool time in 4-cylinder and rotary engines."
Read more: http://www.turbomagazine.com/tech/turp_0611_custom_made_header/viewall.html#ixzz23vxUxvhU
Many debate the usefulness of simple log turbo manifolds versus a header combined with a turbo. It is true that a turbo motor can make lots of power with a log-type manifold. It is also true that a log manifold can spool faster than a tuned manifold. This is because a turbo is driven partly by heat energy and expansion of the hot exhaust gasses. The longer tubes in a tuned header tend to dissipate a lot of this heat energy before the turbo, which can result in more turbo lag. However, turbos can use the pulse energy for better breathing and to help spool the turbo faster as well.
In my experience, log manifolds and a properly engineered tuned manifold will have nearly the same boost onset rpm. The log manifold spools the turbo faster and more violently while the tuned manifold has a smoother, more gradual onset of boost that is more manageable and controllable with the throttle. The engine with a tuned manifold will be snappier off boost. A properly designed, tuned turbo manifold will have from 30-100 more horsepower than an untuned, or log manifold, at the same boost level. It's usually a good trade off. The lag and heat loss of a longer runner tuned turbo manifold can be minimized through the use of stainless steel in the manifolds construction. Stainless has poor thermal conductivity and keeps the heat in the pipes and thus transfers more heat to the turbine. By adding tricks to the manifold design like pulse conversion where the runners 180 degrees out of phase are matched with each other to let the turbine have evenly timed pulses hitting it, the lag can be reduced or even improved over a log manifold while retaining the advantages of a tuned system's good breathing. As an example in a 4-cylinder: you would pair cylinders 1 and 4 with 2 and 3, side-by-side right before the turbine. Doing this with a twin scroll turbine housing makes for a huge improvement in spool time in 4-cylinder and rotary engines."
Read more: http://www.turbomagazine.com/tech/turp_0611_custom_made_header/viewall.html#ixzz23vxUxvhU
9.5"
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