Wadzii's build thread
07-07-2010, 11:00 AM
#32
Banned
Thread Starter
It needed about 10% from 3000 up to redline. I really think the short ram was choking it up.
I don't have and exact length but it goes down between the Rad and cross member then under the passenger side headlight
I don't have and exact length but it goes down between the Rad and cross member then under the passenger side headlight
07-07-2010, 12:31 PM
#33
I wonder how much of the change is due to the increase in diameter (reduced restriction from bigger piping), and how much is due to improvement in harmonics (better combination of length and width). Too bad you didn't get any datalogs of MAP before / after the intake swap...
07-07-2010, 01:00 PM
#34
Originally Posted by wadzii,Jul 7 2010, 09:00 PM
I don't have and exact length but it goes down between the Rad and cross member then under the passenger side headlight
It has some gains in lower revs due to resonances inside the very long pipe.
07-07-2010, 02:47 PM
#35
Banned
Thread Starter
I will do some logging soon with the new intake and compare.. i'll post some screen shots if there are any differences.
even my stock motor seemed to respond better to a long intake vs a short intake.
i'll be testing all this crap on the dyno soon enough though.
The car pulls alot better w/this vs the short 3 inch pipe though
even my stock motor seemed to respond better to a long intake vs a short intake.
i'll be testing all this crap on the dyno soon enough though.
The car pulls alot better w/this vs the short 3 inch pipe though
07-07-2010, 04:00 PM
#36
Dyno proven:
Short pipes will create power gains in lower portions of the powerband
Long pipes will create power gains in the mid to high
So, a 3" long pipe vs a 4" long pipe (same configuration) will most likely give you very similar results.
Short pipes will create power gains in lower portions of the powerband
Long pipes will create power gains in the mid to high
So, a 3" long pipe vs a 4" long pipe (same configuration) will most likely give you very similar results.
07-07-2010, 04:36 PM
#37
Originally Posted by BlackTrax,Jul 7 2010, 04:00 PM
Dyno proven:
Short pipes will create power gains in lower portions of the powerband
Long pipes will create power gains in the mid to high
So, a 3" long pipe vs a 4" long pipe (same configuration) will most likely give you very similar results.
Short pipes will create power gains in lower portions of the powerband
Long pipes will create power gains in the mid to high
So, a 3" long pipe vs a 4" long pipe (same configuration) will most likely give you very similar results.
07-07-2010, 07:09 PM
#38
^^
Fair enough. I need to a bit more clear. What I'm trying to say (w/o taking into account the dynamics of forced air (ducting, ram etc). Also w/o comparing my example with any intake that uses Bernoulli's principle (bubble designed, PWJDM, Mugen, J's etc)....
And using a 3" intake as the example, you will see the same "leaner" results by lengthening your intake regardless if it is 3" or 4".
Hypothetical example:
1) 3" pipe 10" length results = low end gains/no significant top
2) 3" pipe 36" length results = mid to top gain, no significant low
3) 4" pipe 36" length results = will share similarities with result #2. The difference from 3"-4" will not be as significant as the difference from 10" length vs 36" length
So to reply to the original topic, the 10% fuel you're adding more likely due to length than diameter.
True Example: SCCA Street Touring Sport AutoX CRX. Not allowed to do any engine mods other than intake and header. No cutting of fender liners or bumpers to aid in ram air effect. So we make our own intakes, dyno tuned custom lengthed for a specific use. The car does not use high rpms in his type of Autox racing. It was more important to make power between 3-4k rpms than any other rpm range. Below is a 2.5" intake short vs long (I can share that there is a 20" length difference between the two). Only change made was length of tube. All other things stayed constant including tune. My hopes are we can find this information useful.
.-.-. = short intake
...... = long intake
Fair enough. I need to a bit more clear. What I'm trying to say (w/o taking into account the dynamics of forced air (ducting, ram etc). Also w/o comparing my example with any intake that uses Bernoulli's principle (bubble designed, PWJDM, Mugen, J's etc)....
And using a 3" intake as the example, you will see the same "leaner" results by lengthening your intake regardless if it is 3" or 4".
Hypothetical example:
1) 3" pipe 10" length results = low end gains/no significant top
2) 3" pipe 36" length results = mid to top gain, no significant low
3) 4" pipe 36" length results = will share similarities with result #2. The difference from 3"-4" will not be as significant as the difference from 10" length vs 36" length
So to reply to the original topic, the 10% fuel you're adding more likely due to length than diameter.
True Example: SCCA Street Touring Sport AutoX CRX. Not allowed to do any engine mods other than intake and header. No cutting of fender liners or bumpers to aid in ram air effect. So we make our own intakes, dyno tuned custom lengthed for a specific use. The car does not use high rpms in his type of Autox racing. It was more important to make power between 3-4k rpms than any other rpm range. Below is a 2.5" intake short vs long (I can share that there is a 20" length difference between the two). Only change made was length of tube. All other things stayed constant including tune. My hopes are we can find this information useful.
.-.-. = short intake
...... = long intake
07-07-2010, 07:39 PM
#39
What you are seeing is reinforcement of the incoming air by standing wave patterns (harmonics) in the inlet duct.
The longer the duct, the lower frequencies that the harmonics occur. With ITB's you tune the length of the individual runners to the frequency that you want reinforcement. On my race engines if I tune the harmonics to help at 8000rpm, there is a corresponding dip at 4000rpm. There would be a secondary harmonic at 16000rpm but I'm unlikely to get there.
On a shared plenum system, the tube is seeing twice the number of pulses so the length to rpm equation is different.
I've found through dyno work on 4age ITB engines that parallel sided tubes provide better pulse reinforcement than widely tapered mouth trumpets.
The narrower diameter also helps the pulse tuning but often you need a wider diameter to flow the amount of air needed.
Its interesting how the short ramtube helps the lower rpm. 10" is way to short for harmonic tuning, so its probably providing less resistance to flow at lower rpm, whereas the 36" tube is providing harmonic tuning at higher rpm.
The longer the duct, the lower frequencies that the harmonics occur. With ITB's you tune the length of the individual runners to the frequency that you want reinforcement. On my race engines if I tune the harmonics to help at 8000rpm, there is a corresponding dip at 4000rpm. There would be a secondary harmonic at 16000rpm but I'm unlikely to get there.
On a shared plenum system, the tube is seeing twice the number of pulses so the length to rpm equation is different.
I've found through dyno work on 4age ITB engines that parallel sided tubes provide better pulse reinforcement than widely tapered mouth trumpets.
The narrower diameter also helps the pulse tuning but often you need a wider diameter to flow the amount of air needed.
Its interesting how the short ramtube helps the lower rpm. 10" is way to short for harmonic tuning, so its probably providing less resistance to flow at lower rpm, whereas the 36" tube is providing harmonic tuning at higher rpm.
07-08-2010, 05:11 AM
#40
I feel bad for sort of hijacking wadzii's thread, but not so bad that I can't share a couple more points.
My datalogs have shown that short tube intakes provide more gains up top, and long tubes provide more gains down low. I believe this is because low RPMs produce low frequency standing waves which have long wave lengths (benefitting from long pipes). Basically, I think BlackTrax has his plots backwards.
I also believe pipe diameter does change the harmonics of the intake pipe, and it isn't totally about length. Consider a pipe organ. You see that the high pitched pipes are short AND thin, and the low pitch pipes are long AND thick. I don't think the diameter is chosen just by the rate of air flow.
Another example is the porting of sub woofer boxes. When you choose the port size of the sub woofer for your target frequency, the equation for port length does include the cross-sectional area of the port.
My datalogs have shown that short tube intakes provide more gains up top, and long tubes provide more gains down low. I believe this is because low RPMs produce low frequency standing waves which have long wave lengths (benefitting from long pipes). Basically, I think BlackTrax has his plots backwards.
I also believe pipe diameter does change the harmonics of the intake pipe, and it isn't totally about length. Consider a pipe organ. You see that the high pitched pipes are short AND thin, and the low pitch pipes are long AND thick. I don't think the diameter is chosen just by the rate of air flow.
Another example is the porting of sub woofer boxes. When you choose the port size of the sub woofer for your target frequency, the equation for port length does include the cross-sectional area of the port.