Individual Throttle Bodies and Improved Airflow

[Dessertrunner]

quick and dirty numbers,
If I read it right the good book says the intakes are open for 50 degrees of the cycle, that means 6 are open for 300 degrees of possiable 360, so 84% of the time, each cyclinder (i think) flows 175 cfm but that is at full lift so we assume average flow during opening cycle is 60% then
175 time 6 times .6 times .84 gives a possiable 529 cfm.
Using Harvey's number of 549 cfm were are to close for comfort.

I may have done the maths wrong so scream if thats the case, the alarm bells are ringing because all bench flow test were for heads with out any intake restrictions just a straight head.

So have I thrown the cat amougst the pigeons?
Tony

[oab_au]

Originally Posted by Dessertrunner

Hi Trevor good to see you are still alive,

Well as they say in the classics "The proof is in the doing". I (and I think Matt) are on a path to make this work. I bet London to a brick that we get more power.

Mychailo's test was on a standard engine and it shoed that the neg pressure is the same as moving the car to 2,000ft as regards the densitity of the air. My guess if Matt and I stay with the current air intakes but try to get a 50% more power the vacum will go to -2psi. Remember vacums are not the reverse of pressure they behave different.

Should be one hell of a interesting debate.
Have a great day.
Tony

OK, I was on the standard manifold.
With just the throttle bodies, there is not much that will restrict the airflow, but you will have to have a air cleaner of some sort. So you will have to simulate the same conditions, of a plenum or air box, that they can draw their air from, without changing the tuned length, and with no pressure drop.

Getting 50% more power does not mean, using 50% more air. It means, getting the same amount of air into the cylinder, at a higher rpm. You can’t force the air to overfill the cylinder, so you cannot really increase the torque that it has now. The only option we have is to fill the cylinder with the same amount of air at the higher rpm.

For example; if we compare the engine cylinder with other comparable engines cylinder, you can see what I mean.
SVX cc/Cly.
Hp 230 @ 5600 rpm, 67 Hp/Lt
Tor. 228 @ 4800 rpm, ft/Lt
A figure of 69/70 ft/lb/Lt is a good figure for this type of engine that achieves 67 HP/Lt.

If we compare this to the Ducati Multistrada
1200 Multistrada 600cc Cyl.
Hp 150 @ 9250 rpm, 125 HP/Lt.
Tor. 87 @ 7500 rpm, 72.5ft/Lt
The Hp figure has jumped to 125Hp/Lt. almost twice the SVX.

The torque figure has only increased 3 ft/lb. So they have only increased the amount of air in the cylinder by 2%, for a power increase of 86%.
This is the result of producing the torque at 7500 rpm instead of 4800 rpm.

So any increase we can make, is from tuning the inlet and exhaust tracts to have the torque produced at the higher rpm, and extending the valves duration and lift, to allow the same amount of air to fill the cylinder in the shorter time that the higher rpm allows.

What do you reckon?
Harvey.

[Dessertrunner]

Harvey,
An interesting post, the other interesting number from your data is the SVX generates 11.9hp per 1k revs. The bike 13.5hp per 1k, in short it is getting greater HP per rev throught the whole rev range.
Matt only change the exhaust to headers and he felt the motor had a lot more power. I think as you suggest it is all about getting it in and out. I am interest to see the flow bench numbers we get with the intake manfold on.
Do you know if it was the plan to have the power band low on the recent build that Tom did? How would you go about getting it at a higher rev.
Tony

[oab_au]

Originally Posted by Dessertrunner

Harvey,
An interesting post, the other interesting number from your data is the SVX generates 11.9hp per 1k revs. The bike 13.5hp per 1k, in short it is getting greater HP per rev throught the whole rev range. Matt only change the exhaust to headers and he felt the motor had a lot more power. I think as you suggest it is all about getting it in and out. I am interest to see the flow bench numbers we get with the intake manfold on.
Do you know if it was the plan to have the power band low on the recent build that Tom did? How would you go about getting it at a higher rev.
Tony

it is getting greater HP per rev throught the whole rev range.

Yes it does, that’s the way horsepower is calculated. Torque x rpm, equals the Hp. So if we maintain the same torque at higher rpms, up goes the Horsepower.

How would you go about getting it at a higher rev.

If we look at the dyno chart for the engine;

In my opinion, the torque was divided between the resonate peak at 4500 rpm, and the cams breathing peak at 5700 rpm. If the resonate length of that engine, was set to 6000 rpm, the two peaks would occur together, to put the maximum Hp at about 265Hp at 7200 rpm.

Harvey.

[dynomatt]

I really should dyno mine as it is...it seriously feels fast compared to what I had before.

I'm a bit nervous about putting the ITB's on now...don't want to wreck it!!

M

[Trevor]

All of this stems from understanding based on carburettor technology, whereby it was essential the choke tube created a depression within the flow of intake air, i.e. a restriction inserted within the intake duct. Fuel injection does not require such a restriction and therefore the OEM design can without problems, include an intake cross section which is generous/excessive, rather than conservative.

All of this means that increasing the flow through the throttle control system is not necessarily going to be effective, particularly if other alterations requiring an increase in airflow, do not form part of the modifications. The existing arrangement is very probably more than adequate and therefore leeway is built in. Nothing may be gained.

[dynomatt]

So I got mine dyno'd again today. Just to recalibrate my butt, because as you can see, it was out.

This the curve from the car today. You can see AFR's aren't great, so it was never going to smash power records. But when you compare to the other one, you can see some quite significant differences.

This is as it was.


This is overlayed with the curve from before, with the big heads, but stock headers.



A couple of things stand out...IRIS seems to be working quite nicely in the recent one...curve is pretty smooth. None of the irregularities of the first one.

Harvey...I reckon with the good heads, and the ITB's the power curve should keep going up like the torque curve...what do you think?

M

[dynomatt]

Harvey...no response?

[oab_au]

Originally Posted by dynomatt

Harvey...no response?

Sorry mate pressed for time.

A couple of things stand out...IRIS seems to be working quite nicely in the recent one...curve is pretty smooth. None of the irregularities of the first one.

The things that stand out to me is that you have driven the last rally with a standard engine, plus the exhaust. You reckoned that it was fast with smooth torque flow.
That is what I have been saying, that you need the car to be easy to drive to be fast. It is a different requirement to say, Dans road race engine. In your sort of event you need a wide smooth torque curve that you can use any gear at any speed to get good drive out of the engine.

When you chase the HP numbers, up the rev range, you will have an engine that has large amounts of wheel spinning HP over a narrow rev range, so you have to 'row the box' to keep the drive on.
Just my opinion.

Harvey...I reckon with the good heads, and the ITB's the power curve should keep going up like the torque curve...what do you think?

Yes if the Exhaust length matches the Inlet length, the torque won't increase by much, but it will move up to a higher rpm, this will send the HP up as a result.
It is hard to get a handle on where you are now, if you can tell me more about the exhaust that you fitted and what the valve timing figures are, we can tell a bit more on what the outcome will be.
Have you got a picture of the exhaust? What length are the pipes?

Harvey.

[dynomatt]

Harvey,

The headers I had made have 32" primaries in 1 3/4" to a 3:1 collector each side. Then secondaries are 2" for 16". Then into a 2 1/2" single system.

Valve timing figures are in this thread...I'll get them.

M

[oab_au]

Originally Posted by dynomatt

Harvey,

The headers I had made have 32" primaries in 1 3/4" to a 3:1 collector each side. Then secondaries are 2" for 16". Then into a 2 1/2" single system.

Valve timing figures are in this thread...I'll get them.

M

Is there an expansion point in the system? where? muffler?
A photo saves a lot of questions.

Harvey.

[Dessertrunner]

Matt and I have been talking about the roller throttles and he suggested that I rethink having them go inbetween the existing Intake manifold & while I am at it why no shift the injectors to the top of the ram pipe. This then begs the question what changes do we need to make and what is the ideal size for the for the port throught the roller throttle. I personally have concerns about the area were the injector is as this are gets larger then either the area before or after in the intake path. It would result in a low pressure area which I feel could screw up the air getting into the head.
Yesterday we had a long debut about what benfit checking the flow rate of a standard head with all the intake attached. My point was you can report the head but in the real world you can not say for sure if when you put the head back on the motor you got any improved airflow. We assume it was of benfit and assumptions have a habit of bitting you on the ass later.
I will discuss the tests we plan to do later in more detail right now I will post a plug design that will be clamped on the top of the head with a 100mm long ram pipe. The plugs & ram pipes are in 3 dia at the top, 40mm, 45mm & 50mm. We have also assumed that we fill the cut in the head for the injector.

[TomsSVX]

Originally Posted by Dessertrunner

Matt and I have been talking about the roller throttles and he suggested that I rethink having them go inbetween the existing Intake manifold & while I am at it why no shift the injectors to the top of the ram pipe. This then begs the question what changes do we need to make and what is the ideal size for the for the port throught the roller throttle. I personally have concerns about the area were the injector is as this are gets larger then either the area before or after in the intake path. It would result in a low pressure area which I feel could screw up the air getting into the head.
Yesterday we had a long debut about what benfit checking the flow rate of a standard head with all the intake attached. My point was you can report the head but in the real world you can not say for sure if when you put the head back on the motor you got any improved airflow. We assume it was of benfit and assumptions have a habit of bitting you on the ass later.
I will discuss the tests we plan to do later in more detail right now I will post a plug design that will be clamped on the top of the head with a 100mm long ram pipe. The plugs & ram pipes are in 3 dia at the top, 40mm, 45mm & 50mm. We have also assumed that we fill the cut in the head for the injector.

I am confused as to why you insist on using the stock manifold? Yes it is easy because you don't have to make it... but then you cannot use tuned length velocity stacks like I know you want to

Port the heads, match the headers to the flow of the heads post porting. Then match the intake stack length and diameter and bell with all of this so they work together. Route the stacks into a common plenum which you can feed off an intake or two from wherever you like...

I did something similar with the s/c intake on my silver... Considering the heads were not ported or flow tested I was shooting in the dark, I made velocity stacks that all fed off of the common plenum which was fed by the discharge of the blower. This allotted a considerable ability to breathe better in the upper RPM range as the air being forced into the cylinders had a better sense of direction and equal range from the plenum.

If I were you, I would build a plenum similar to the one I built for my car but cut out the top to fit a large flat element and use a hood scoop for forced induction of ambient pressure at speed. This will leave you with less turns for the air to make, equal distribution to all cylinders, AND an overall higher ambient pressure at speed thus making it more efficient and powerful... Just make sure you have your heads ported for equal flow and headers to match

Tom

[Dessertrunner]

Sorry forgot one further point of interest,
The cross sectional areas in mm2 of interest are,
50mm 1,963
45mm 1,590
40mm 1,256
Current injector area were it meets the head 1,909 (shape is bad for airflow)
My planned head meets manifold 1,848
Total of the 2 pasages behind valve 1,608 (will have higher drag due to greater surface area)

Have a great day.
Tony

[Dessertrunner]

Intake flow parth