Harley Davidson V-Rod Forum banner

Plenums

74K views 402 replies 52 participants last post by  mukle 
#1 ·
Do we really need them?
This is the question that I am researching right now.

Turbo or Supercharged piston engines typically use many cylinders arranged in-line and one or two superchargers. Superchargers deliver air at a relatively constant rate, while cylinders demand it in a varying manner, as the valves open and as piston speed varies through the stroke. Simple direct ducting would give problems where the nearest cylinders received more airflow. The pulsating demand from the cylinders would also show problems of either pressure waves in the duct, or a shortage of inlet air towards the end of the inlet phase.

The solution is to provide a large-volume plenum chamber between the inlet and the cylinders. This has two benefits: it evens out the difference in path restriction between cylinders (distribution across space), secondly it provides a large-volume buffer against pressure changes (distribution over time
 
#149 ·
Steve, Does this match up with what we need ? ....
Maybe. The resistance of that sensor is too high at low temperatures, fairly close at mid-temperatures, and a little too low at high temperatures.

Here's a table (chart is in Post #152) showing the errors at the three temperatures shown in the link:
ECM__________actual
air_____________air
Temp._________Temp.
°F___°C______°F___°C
25___- 4______48___9
89___32______87___31
162__72_____146___63
 
#145 ·
WOW...There is alot of great info in this tread.

Saying that, I just want to say that we can redesign a better plenum.

I do not think we are going to make a perfect plenum.

We would be here until we are all 100 years old.

I just want to keep it simple enough that it works well with our setups.

The adapter is going to be a great improvment to what we have.

I am asking if we are overdoing it?
Opinions!!!!!

Now to build up from there.
 
#146 ·
This is one of the most hit threads on the Forum. It looks like we'll end up with 2-3 designs that fit the power profiles of different riders. I appreciate that whatever someones area of expertise they are posting their bit. We're covering better IAT's, nitrous install, wave harmonics, aluminum fabrication, please post links if you come across anything that we can use, parts to tech to offers to help ! I'd also like to thank a good half dozen of you that have phoned & sent personal emails. As my pieces come in I'll document my progress with photos & the thought process. To complete this we'll need input on electric water pumps, radiator hoses, positive crankcase ventilation, just to get started. Be part of the action !
 
#150 ·
Ozracer, the issue is to reroute the coolant lines to allow side entry to the plenum. As long as I'm moving stuff & buying pats, I thought i'd investigate converting to an electric water pump to save HP. Flow is constant, when needed, with an electric, look up what kind of parasitic losses are required to run the mechanical pump at 10,000 rpm ! Steve, when I'm investigating these, what do I ask for ? Is this called the resistance chart or what ? DUH
 
#152 ·
....when I'm investigating these, what do I ask for ? Is this called the resistance chart or what ? DUH
Yes a resistance chart is as good a name as any. Look for several data points between the plenum air temperatures you expect to see. I would guess that plenum air temperatures as cold as 25 °F and as hot as 180 °F (maybe higher without an intercooler) are to be expected. The sensor you linked to has the minimal amount of data (three points) but more points would be better to show how the sensor response deviates from a straight line. In Excel the data can be plotted on a chart and the OEM curve compared to aftermarket data.
 

Attachments

#151 ·
One of the things I know about boost is cooler intake temps means more air to the cylinder. Has anyone looked into an inline liquid cooler heat exchanger with an external radiator and electric coolant pump and electric fans similar in theory to those used in PC cooling vs the usual external large volume lag creating air coolers?

My phone is better than your phone....
 
#153 ·
Met member Mukle tonight...here is an output couple of hours later:notworth:.

Now the IAT is palced.

Is there still something to improve, or shall we start production:D?

 
#155 ·
Yes...and a boost leak via open IAC as well.
(IAC does not park to 0 step while throttle is added. It stays where it was on idle or goes to defined XX steps parking position)
 
#157 ·
Karzza,

Why the rear intake and not the front?

Have you come up with a base plate to fit over the runners?

Are you intending to weld onto the runners with the Y set up?
 
#160 ·
Karzza,

a)Why the rear intake and not the front?
b)Have you come up with a base plate to fit over the runners?
c)Are you intending to weld onto the runners with the Y set up?
d)If a person is spraying Meth or Nos, how is this going to affect the IAT sensor. You will be spraying right on the sensor.
a) In the rear intake there is more space around and all screws are not on IAT's way.
b) no, You can design it. At the moment I'm stucked to the Y-idea.
c) I will start with 90deg 60mm silicone elbows from the flange, then 90deg 60mm aluminium elbows welded to 30deg 60mm aluminium elbow and the last a silicone elbow to IC.
d) yes, it could effect by increasing fuel. NTC part of IAT appears very little in a port and airflow takes meth/NOS mostly downwards. Better ideas for the IAT location with extra injectors?
 
#158 ·
one more question...

If a person is spraying Meth or Nos, how is this going to affect the IAT sensor.

You will be spraying right on the sensor.
 
#161 ·
90deg 60mm aluminium elbows welded to 30deg 60mm aluminium elbow...

can you make a couple extras up? :D


Karzza,
Are you going to make this a kit with the mounting bolts and new IAT sensor, and plugs for the rest of the ports.

Are you supplying all o-rings?
 
#167 ·
Thought I'd post a couple pics of the starting point for my take on the new plenum. My effort is directed at improving the flow & distribution. I found this neat adapter for the T25 on Ebay for about $25. It uses a 2" charge pipe rather than the 1 3/4" in the kit. The 2" aluminum elbow has a larger radius as well. I'll connect these with a silicone coupler and sweep it back to a side entry on the plenum.
 

Attachments

#169 ·
It would not be strictly a HP gain from better flow. A turbo works against itself if either the intake or exhaust side have restrictions. It appears that the intake side has a couple places that could be optimized. The outlet from the compressor wheel is 1.75" which gives a total cross section of 2.42 sq in. this gets impaired by each turn, the length of the charge tube, and the reduced inlet opening to the plenum. The 2" pipe has a cross section of 3.14 sq in, which is over 20% larger, will be shorter and have less turns. This should be; less heat, faster spool, less parasitic drag on the turbine and compressor. How much & at what rpm it makes a difference, we'll have to see. I also believe that the more you push the turbo the more critical flow becomes ( which is why porting gives bigger results on forced induction than on NA motors ! ).
 
#172 ·
Yep, my idea is similar plus some additional options.
We will produce 10pcs of them.
 
#174 ·
#175 ·
USD
200= $256.00
300= $384.00

@Karzza, Can you come up with a Y tub set for the the inlet charge tube connection?
This would be from the top of the adapter up to the where the Y becomes one tube.

Would be a great help to me if you could do the y tube set up. #

1. I am in.

Rod
 
#176 ·
Good Work Doug!!

I'll give you a call this weekend.

I have another idea to talk about.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top