We had exhaust manifold/header design. How about intake manifold design?

[Ma70.Ent]

Our VE is 88%, correct? I need to know what it is so I can make some calculations on my own (or at least attempt to)

Also, does anyone have calculations on what the plenum volume should be?

Also, an interesting reason why ACIS might not be optimal for higher RPM performance:

we can use 2 sets of runners with different lengths in one IM in order to have 2 different peak torques and overcome this tradeoff. However, the penalty for using 2 sets of runners is an increase in surface area which diminishes flow quality at higher rpm and therefore limit upper rpm power (eg. Integra GSR's 2 stage IM with dual variable length runners ). The problem of added area is neatly solved in the new 4th generation Integra RSX Type S 2 stage IM by using a roller valve. ]

Finally, even if we have a tuned Intake Manifold, how will I tune the exhaust manifold/collector setup/exhaust system to keep the peak torque the same as what I calculated in the intake manifold? In other words, how do I make it so that my exhaust system doesn't effect my Intake Manifold calculations for peak torque at XX RPM?

 

[sarinas_dragons]

I refer to that as our ME or mechanical efficiency. There is a reason to distinguish thermal, volumetric and mechanical efficiencies.

To most directly answer you it would matter for what calculations you need the data. The VE varies with the engine rpm. The way to calculate that is to establish the load parameters for fuel, back into the air and set it against the thermal efficiency. I have this in a massive spreadsheet that I'm unable to share due to its size.

The VE is also camshaft design and timing dependent. The intake valve closing actually sets the mechanical volume trapped against the swept volume. This mechanical efficiency acts as a constant in many observations of performance. The thermal efficiency can be used to guide aims of making power or to analyze power already made.

It is advantageous to reverse-engineer the 7M. At least with the undrestanding of how the performance was achieved, upgrades would be able to be made.

 

[Ma70.Ent]

Ahh, so I can't plug in 88% for VE in all of those equations above? I wonder how they get it.

 

[sarinas_dragons]

Forget that. The nature of the equations is that they fit the discussion or article. This was intended for an audience and the perception of their receptivity to the real knowledge, instead of a toilet-time diversion it is...

You need the only data, not their's. I've asked alot of people and they tell me I'm on my own.

The reason they cannot get into the explanation is the lack of data. I was asked on cs to compare an LS7 to the 5M. The biggest difference is the bore size. The thing the bore size affects is the duration the flamefront has to burn to reach the margins of the chamber. So chambers are squished to small areas.

The way they get it is to talk about a theoretical and once you accept their model it is fantasy. But the reality is there is a range of load and those parameters are considered against the rest. What dynos don't even consider are the wind resistance forces....

What are you going to figure out? If I've already done it I'll just post it.

Where I inevitably start is a mach index study, presuming I have the specs to begin. This shows the intake charge speeds the designers used to aim for powerbands. I just finished a M/i study for the 5MGE engine with a 7M head, kinda the same idea of 2J and 1J. I'll post a 7MGE M/i study. I'll usually overlay the intake charge speeds to the rpms, too. This is necessary anyway when it comes to comparing the intake charge speed to the piston speed.

This allows us to compare the revs where the cam lift allow a certain speed to the valve. This shows us where the factory torque and horsepower occur in terms of intake charge speed and rpm and this is very informative.

 

[MrWOT]

Where did you put the pitot? With valves or without? If with, lift, etc. I'm just getting ready to work a GE head myself

From the numbers, looks like I'm going to need significant ammounts of epoxy, barely hitting .6 mach at 8k! Yeesh.

 

[Ma70.Ent]

What are you going to figure out? If I've already done it I'll just post it.

I was attempting to use those formulas to try and figure out plenum volume, runner length, and stuff like that. I guess it was far too simple to be true.

So at our maximum redline, we have around .495 Mach Index (or Mach .495) and .600 is where the best volumetric efficiency is? What else can we use this for? I'm not too sure cause this stuff is way over my head

 

[MrWOT]

You want an AVERAGE mach index of around .6, it will be faster and slower at some points, slower around the ssr, faster at the throat, and that doesn't make for VE. VE is determined by your cams, and like Sarinas said, varies widely with rpm.

 

[Ma70.Ent]

Does this link look half-decent for good information?

http://www.installuniversity.com/in...metric_efficiency/ve_computation_9.012000.htm

 

[sarinas_dragons]

Yes, that is concise. But I regard the article as oversimplification. For the study above I did sixty computations to come up with the inputs for the separate cells in the first column.

I've noticed that there has to be an engineer's desire to be thorough, instead of just know a fact or have a bitchin' runnin' engine.

This is not the first time I've had to inititate a nerd in denial...

NERD

Aaaannnnd, in my twenties I was a Seattle fireman. Tradition demanded a response to a question like- "hey, where is the pitot" no less than "did you look under your foreskin?" or "...if it was up your ass you'd know where it was". This was just to let a little respect and appreciation, the utter reverence show of our feelings toward the existence of the new guy.

One of the things we want to start bringing into the discussion is the learning of the way to unite the events of the crankshaft with the events of the camshafts. In the different phases of the cycle certain things occur. The engineers were aware of the relation of these events but it is so cumbersome and dry and unrewarding that we want the microwave, only know the microwave version.

The mach index study reflects the momentary action of the intake charge speed. It is a model of the stock parts performance and shows what is happening in the stock engine. Many different events have to be looked at in reference to a common timing.

In direct response to the question about the relation of VE to M/i- VE follows the torque curve. To understand the application of the chart to the VE look where stock torque peak occurs. This is still far-flung. To get to a better understanding consider this-

The engine can safely cruise at an afr higher than it needs at full-power. Cruise and full-power can use the same mass of air but a different mass of fuel due to load. Also, one needs to consider the instantaneous nature of our brief glimpse set against the understanding of the dynamic nature of the operation.

For a valve seat dimension the valve comes off the seat in increments. The initial increments and the interaction of the intake charge speed create completely different conditions in the first thirty-two degrees of the clearance ramp of the intake cam. Charge speeds briefly achieve far higher than the chart shows. If the actual nozzle math is done per degree a complete understand is easier to achieve with complete data. But without complete data there is little else to know.

The clearance ramp events of the camshaft are significant due to the ratio of time they consume in the cycle.

 

[MrWOT]

<---- Just for you SD

 

[sarinas_dragons]

Okay, on cs i just made a request for the molar weights of air and gasoline overlaid to captured volume for a 5MGE.... and a shruberry.

I will have to consider how to end this initiation....

It will involve filling voids in the information about the 7MGE specs. I was in preparation for the 8MGE build, going to fingerprint the stock cams. Into consideration I wanted to take as I measured the next firing cylinder's power pulse.

From the engine's design the next firing cyinder is predictable, and something else for which the Toyota engineers have never had to answer.

 

[Ma70.Ent]

Discussion has seemed to die down, so I'll unsticky this for now.

 

[sarinas_dragons]

Revival! How did your application of the VE do for the equations?