looking for 300+ hp

[K2e2vin]

Originally posted by MikeBergy@May 8 2004, 11:17 AM

The engine that is making more power, regardless of boost pressure, IS FLOWING MORE CFM.

Wrong. The engine is burning a larger MASS of air. CFM is volume, limited to engine displacement and rpm.

i agree with bergy...do some math and you will figure it out...

 

[K2e2vin]

fuck it ill do the math...lets use 10psi max boost(1.78 bar with intercooler pressure drop), 140degree post intercooler, and gsr engine(1.8L), and by the way these flow arent with the head, its based on rpm and displacement...

for 10psi(@certain rpm), this is the neccesary cfm:
4500rpm=19lbs/min
5500rpm=23lbs/min
6500rpm=27lbs/min
7500rpm=31lbs/min
8000rpm=35lbs/min

 

[turboB20hatch]

i dont understand why mikebergy keeps arguing the same wrong point

 

[MikeBergy]

Originally posted by K2e2vin@May 10 2004, 11:53 AM
fuck it ill do the math...lets use 10psi max boost(1.78 bar with intercooler pressure drop), 140degree post intercooler, and gsr engine(1.8L), and by the way these flow arent with the head, its based on rpm and displacement...

for 10psi(@certain rpm), this is the neccesary cfm:
4500rpm=19lbs/min
5500rpm=23lbs/min
6500rpm=27lbs/min
7500rpm=31lbs/min
8000rpm=35lbs/min

I'm glad you agree with me but your units are off. Lets assume 1834cc of displacement (ls block).

VFR=Volume flow rate = Area*Velocity = Volume*Cycles Per second.
since a 4-stroke motor cycles through its complete cycle every 2 revolutions, divide this by 2.
@ 3500 rpm Your cfms (in the CORRECT units) are:
1834cc*(1cu. inch/2.54^3 cc)*(1 cu. foot/1728cu. inchs)*3500rpm/2
= 113.342 cubic feet per minute.
@ 4500 rpm
1834cc*(1cu. inch/2.54^3 cc)*(1 cu. foot/1728cu. inchs)*4500rpm/2
= 145.72 cubic feet per minute.
and so on. Pressure and temp. has nothing to do with the vfr of the motor. They DO however have everything to do with the mass flow rate of the motor, measured in pounds of air per minute.

Now lets see how pressure and temperature affect mass flow rate.
Lets look at 10 psi of pressure. Given an isentropic compressor, meaning that the efficiency of the turbo is not an issue, we could say that @ 3500 rpm:

Mass flux = mdot = Air Density*VFR
Given: Atmospheric Standard Day; p1 = 14.7 psi , t1 = 77F
dP = 10 psi, so p2 = 24.7psi
t2 = t1(p2/p1)^((k-1)/k), assuming a constant specific heat k = 1.4 for air.

therefore t2 = 537Rankine*(24.7/14.7)^.2875 = 622.8Rankine = 162.8 degrees F

Now by assuming air to be an ideal gas,
Air Density = p2/(R*t2)

= 24.7 lbf/sq.in. /(1716 ft lbf/slug/degreeR * 622.8 degreesR)* 144sq in./sq ft.

= .003328 slugs /cu ft.



mdot @ 3500 rpm = .003328 slugs/ cu ft. * 113.342 cu ft./ min = .3772 slugs/ min = 12.14 lbm/min

mdot @ 4500 rpm = .003328 slugs/ cu ft. * 145.72 cu ft./ min = .4849 slugs/ min = 15.62 lbm/min

As you can see by the equations, air density varies directly with pressure and inversely with temperature. You raise the pressure, you increase the mass flux. But with that pressure increase comes an increase in temp, and this temp offsets the mass flux in a negative direction. Also notice that I didn't take into account the compressor actual efficiencies, which are less than isentropic. a drop in efficiency will yield an increase in air temp, and therefore a decrease in air density, decreasing the mass flow.

Don't start talking about about thermodynamics if you've never cracked open the books. Most of you have more hands on experience with turbo setups, and I won't argue with you about how to size a turbo, because I have not really had a lot of experience with sizing a turbo. But I will tell you that I have written a hell of a lot more lab reports on compressible and incompressible flow experiments than most of you. Be an engineer if you think your knowledge of these matters is good. You'll make money telling people what you think about turbine and compressor efficiency and how to build a turbo system. Damn good money. I'll be there in a year. see ya.

 

[phunky.buddha]

Originally posted by JD+-->

Whoa up there. When we have P, pressure, as 10 psia and 15 psia, where do you get T = P from?   :roll:

Originally posted by Calesta+-->

Temperature will vary with pressure when everything else is kept constant.

I never said differently, the operative word is significantly. I said it doesn't vary significantly for this application.

Damn, you're really good at not reading everything, huh?

Originally posted by Calesta
Temperature will vary with pressure when everything else is kept constant.

I don't bother to find a graphic for the little "varies directly with" symbol so you decide to ignore the next line of text which explains it anyway, huh?

:roll: :roll: :roll:

Originally posted by MikeBergy
Calesta shoulda said T/P=constant; anyway, he made that point in words after he put that up.

Learn to read, JD.

JD@
Pressure/volume diagrams?  Why don't you simply state Boyle's Law without all the jargon and footwork?

That is Boyle's law, just not the PV = PV simplistic variant. I just decided to explain what everything is rather than throw something out there that I really didn't know and expect everyone to believe it. Maybe you should learn to read instead of just finding one little thing in my post that was explained anyway and try to pick it apart. You might learn something.

JD
How about we trade out my abilities as a math tutor, mister I can't balance an equation?

Again, why don't you learn to read what the fuck I wrote instead of resorting to name calling and slandering when you choose to ignore what the fuck I wrote.

Just like I said in the first line... someone's always going to misunderstand everything and flame anyway. Fuck it. I'm not posting in here anymore, there are too many

GODDAMN FUCKING RETARDED POSTURING ASSHOLES IN HERE WHO CAN'T FUCKING READ!!!

 

[K2e2vin]

oh i just noticed...thnks for pointing that out, but most turbo maps show air flow in lbs/min.

 

[MikeBergy]

[SIZE=14]GODDAMN FUCKING RETARDED POSTURING ASSHOLES IN HERE WHO CAN'T FUCKING READ!!! [/SIZE]

lmmfao!!!!!!! It's alright Mike, you are making the real money anyway, they are just jealous. I'm off to thermo class now. Later

 

[posol]

why are you wrong?

here's why.

because different turbos, in your example- t3 super 60 vs sc61- the sc 61 is going to create MORE DENSE air. thus, fitting MORE air into a similar volume.

so, even though C motor flows Y cfm, bigger turbo will be throwing in more cfm, regardless of the engine size.

 

[MikeBergy]

because different turbos, in your example- t3 super 60 vs sc61- the sc 61 is going to create MORE DENSE air. thus, fitting MORE air into a similar volume.

so, even though C motor flows Y cfm, bigger turbo will be throwing in more cfm, regardless of the engine size.

You seriously did not read my last post. And you obviously don't know jack about thermodynamics. I don't know jack about computers, but if a question regarding networking crap or javascript or whatever came up, and we were debating it, I wouldn't proceed to try to prove you wrong using weak arguments that do nothing but strengthen your position. That is what you are doing. Thanks
Mike

 

[dohch22a4]

Wow. That's the first time i've ever seen Cal blow up. This thread is hardcore.

 

[spectacle]

Originally posted by dohch22a4@May 10 2004, 10:48 PM
Wow. That's the first time i've ever seen Cal blow up. This thread is hardcore.

ditto.

now could somebody tell R.E.Development what size injectors to use?

 

[MikeBergy]

It was in the 2nd post of this thread, lol

 

[spectacle]

ok, just wanted to make sure his question got answered. my postwhoring = over!

 

[driverunknown]

With all the thermodynamics aside and the "Oh I'm gonna be so successful, I might just suck my own dick" attitude, I just don't understand why people would argue that Jeff is wrong and a <insert bad name here>if he does this for a living. Why would he spread misinformation all over the internet? Wouldn't that hurt his business? As far as I can remember Hondaswap is still a popular tech site. I know some of you guys like to compare dicks on the internet because you'll never meet each other in real life, but thats just gay. There is a reason that IBSpec is still in business.

By the way Calesta- I laughed my ass off with your last post, but I couldn't agree more.

 

[Import Builders]

I don;t think anyone here is pissed or mocking me. The post before was a misunderstanding. The guy thought I was talking about different abuses on a motor with the SAME turbo.

I was arguing 2 different sizes. Dumb misunderstandings. I cleared it up with him, and him with me and we are friends. I quite like the guy actually. Much respect to a guy who can think for himself, does his own work and researches things.

Thank you for your positive comments. Its positive comments like this that "I blieve" make this web site so special and nice to be on.

When this site turns into "drama-tech" I will be gone. its not at all.

Jeff

 

[liquid00meth]

Originally posted by Joseph Davis+May 7 2004, 04:45 AM-->

Walk us through the math that demonstrates how 5 psi extra intake pressure results in the adiabatic heating of intake charge that would result in a loss in engine longevity.  Keep in mind every 7-10 deg F rise in temp is equivalent to losing a point of octane. 

I really want to see the big difference in intake temps that's going to directly correlate to knock threshold and engine longevity.  I'm waiting with bated breath. 

Originally posted by Import Builders+-->

The less boosted, more powerful motor is going to wear less.

Horseshit.

Originally posted by Import Builders
Its people that say otherwise that are really spreading misinformation.  More pressure=more heat.  more heat=more wear more wear=rebuild sooner.

I won't argue that more heat = wear and tear... that's common sense. I wholeheartedly argue that there is any *significant* increase in pressure/heat from the intake tract in the setup I have outlined above.

Now, stunna, let's look at the whole picture of what is going on here. You know, the shit you are missing? We're going back to your lopsided 375 whp @ 10 psi versus 300 whp @ 15 psi example you seem to think is relevant to anything.

The engine that is making more power, regardless of boost pressure, IS FLOWING MORE CFM.

This means MORE AIR IS ENTERING THE MORE POWERFUL ENGINE'S COMBUSTION CHAMBER.

You get a HELL OF A LOT more combustion chamber PRESSURE which means MORE HEAT off of the larger amount of fuel being burned in the 375 whp engine. The simple goddamn physics of the matter is that the 375 whp produces more heat-energy than the 300 whp engine does, which is why it makes more power. MORE HEAT EQUALS MORE WEAR - I AM AGREEING WITH YOU, YES?

I have not even mentioned the adiabatic heating the larger intake charge of the 375 whp engine undergoes on the compression stroke, due to the increased dynamic CR anbd cylinder filling associated with being a higher output setup, which is going to surpass the heating effects of the energy represented in the intake charge itself.



Import Builders@
more boost with same compression motor = more heat

Wrong. More power output is directly related to more heat. Read the above passages a second or third time if still confused.


Import Builders

With everything being equal, I believe this is a scientific fact. 

With nothing you've said equalling up - most notably our intellects and educational backgrounds - I believe you to be uninformed and I also believe you to be a jackass for using your position in the Honda aftermarket to spread disinformation. You've taken valuable, small bits of information you've gathered along your career as an intelligent skilled layperson and made sweeping generalizations from them. At no time did you bother to acquire the theory required to help you prove/disprove, and especially to help you understand you held a puzzle piece and not the whole picture.

You need to do what I did - 13 years ago at age 15 - and take a college level engineering physics class. Pay really good attention to thermodynamics and pressure enthalpy conversions. If you have any questions I am more than happy to answer them for you.


Your power output is limited by nothing more than the physical strength of your bottom end and detonation. Do we all agree now, or do I have to explain further, and refer to published papers, SAE and otherwise? Us insomniacs have nothing better to do.

Now, if you will excuse me, the prodigal son of pgmfi.org needs to go to bed. I find that if I don't assume the unconscious fetal position for a minimum of four hours out of every 72 I start becoming cranky.

Hey buddy, while your on the topic of making fun of peoples educations, why don't you do what I did and take a year worth of engineering physics more like this year. If you did, I'm sure you'd remember that adiabatic processes are ones which no heat is gained or lost. So "adibatic heating" is like saying "I dried off my car with a hose." It makes no sense chief. On that note, I'd like to back up the people here who actually do have an education.

And what IB is saying about the turbo size directly correlates to compressor maps. I'm sure if you could read one you'd understand, but maybe you didn't get that in your whole semester of physics. Operating a smaller turbo a, and a larger turbo, b, at whatever PSI that results in the same CFM, there is a real good chance that the smaller turbo is going to spitting more heat into the engine. It's a fact of air compressors. You start getting out of their ideal operating range, things start heating up. It's easy to prove too. Shoot a gallon/second of water out of a sewer pipe (the larger turbo outlet) or a straw (the smaller turbo). at 1gal/s, the pressure in the straw is much higher than the sewer pipe. I'll give you one guess what pressure indirectly equals. You must have gotten that in your year of physics.

And yeah, miraculously, you've gotten something right when you say that the engine making more power is flowing more cfm. That is absolutely correct. But think about where that cfm came from. The turbo. I'm not saying IBs example was correct, because it may not be a good one. But what I do know is at the same hp level, say 300hp, the smaller turbo makes more heat to do it, and therefore can cause more wear on the engine.

In what I said in my earlier post, that CFM (compression and rpm also) is the best place to start if you want to know how much stress is on your engine. But the next place to look for longevity is the heat. And if you've got a smaller turbo runnning larger psi than it's efficiency range, its throwing more heat than the larger turbo which IS in its efficiency range. Bottom line. And that is simple physics.




And by the way, next time you roll up here and try to use terms like "adiabatic heating" and boast about how you were a child prodigy or something, I'm really going to put you in your place. Trying to make other people feel stupid using your shitty education is not what this site is about. But if you want to bring it to that level, feel free to get owned there.

Terms that you have used that you made up completely:
1. Adibatic Heating
2. Disinformation.


So maybe if you have some questions for me about thermodynamics, you can kindly PM them to me. At that time I will tell you to go fuck yourself, and to buy a physics book.

Peace.

 

[MikeBergy]

a few hours late to the flame party, but at least you're here. Ha

edit: read my post above about CFMs. It is not misinformation, it is thermodynamics. Everyone here for some reason confuses volumetric flow rate with mass flow rate, I don't understand why? Whatever, somebody please kill this thread.

 

[Import Builders]

liqued, he didn't mean it man. Me and Joseph are friends.

he is a really nice guy actually. Maybe some posts should be edited to stop giving people the wrong impression?

Anyway, the fires out!

haha

Jeff

 

[MikeBergy]

Jeff, you are way too nice. lol

 

[liquid00meth]

Originally posted by Import Builders@May 11 2004, 12:24 AM
liqued, he didn't mean it man. Me and Joseph are friends.

he is a really nice guy actually. Maybe some posts should be edited to stop giving people the wrong impression?

Anyway, the fires out!

haha

Jeff

His posts should be edited to take out the horse shit.