shoestring
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- Joined
- Jun 20, 2009
- Location
- Swampscott, 01907
6300-6500 something like that
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Stock B230FK/FT with Pulsar/Garrett GTX3076R - Dyno Result
- Thread starter ludi
- Start date
Truebeliever
Active member
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- Aug 5, 2018
- Location
- Charleston sc
For what it’s worth, the kl racing shitty intake is about 8” runner length
You just also take into account cam duration on wave tuning.
Length just gives you the number of waves that bounce around, when you use cam duration in the equation you tell the wave at what time (crank angle and valve events) to arrive with high pressure and low pressure waves.
Edit: I used "constructive" and "destructive" waves in the original post, which is misleading. They do exist in intake and exhaust tuning, but most people focus on the single wave order high and low pressure waves. When you have overlapping high pressure waves you'll get a constructive wave set, overlapping low pressure waves gives you a destructive wave.
More nerdiness: Calculating when this happens is not too much more difficult if using a spreadsheet (maybe even pipemax?), but is hard when doing it by hand. So if you're interested in wave tuning, use something that can handle repetitive tasks and math (excel, google sheets, matlab, etc).
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shoestring
Well-known member
- Joined
- Jun 20, 2009
- Location
- Swampscott, 01907
What if I want to construct destruction?
Sorry man, I got like 3 hours of sleep last night so this is what you guys are in for today. Plus I'm at work. You know what happens at the dealership the day after Thanksgiving? Guys tyin' up bandwidth croozin Tbricks is what...
Totally a valid thing to do if you're timing is right
I wish I had access to all of the tools I built up for other companies regarding engine tuning and setup. The wave harmonic tool I built up was really neat, and I could make it again in probably 3-6hrs if I just sat down and did it. Same for piston acceleration per degree with added in forces depending on component weight. It's just time
What I can say regarding runner lengths, everyone focuses on the 3rd harmonic as it's the easiest to package. But the 1/2/3 harmonics all have very strong destructive wave points that hurt performance. Going with (generally) shorter runners allows for better "fill" in the destructive areas without a killing low end torque more than a few %. So if the engine needs to work in a large RPM range (more than ~2000 rpm) then you really need to work on minimizing the losses from destructive waves and low pressure waves arriving at the wrong time.
Hopefully the coffee at work is good! I'm browsing TB with the morning coffee before finishing up a mondo wire harness drawing for work (220+ wires, ~45 connectors). Then off into the garage to finish putting the Sunnen rod hone together, and then poking around something @towerymt sent over to me.
Sjeng
Active member
- Joined
- Sep 3, 2017
Should work I think.
Interesting,
Any examples of formulas you use?
I have seen: (Dur/360)*(60/RPM)*(331,3+(0,606*T1))/(2*Puls)=insugslängd i meter
With dur in lift at 0.050.
But obviously this is an empiric formula.
Would be interesting to know the background.
In this formula the cam duration has little influence on the tuned length, for sensible camshaft durations.
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I use the formula from Grape Ape Racing which can be found here:
L= ((ECD × 0.25 × V × 2) ÷ (rpm × RV)) - ½D.
ECD (effective cam duration) = 720-Advertised Duration - ~30°
V= speed of sound in hot air, typically 1200-1300fps
RV = reflected wave number
D= diameter of runner+port, avg
The formula is derived from wave speed with one open end and the other closed. Its goal is to have a high pressure wave at the intake valve when it opens.
It’s odd that the equation you posted doesn’t take into account the pipe ID.