looking for 300+ hp

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Like I said, psi is psi, measured at the manifold, independent of the size of turbo. Obviously, different psi will make different power.
 
Yes, manifold pressure is manifold pressure regardless of what turbo is pushing it. If the pressure is the same but the turbos are different, one air charge will be more heat soaked than another, and have a lower oxygen density. You'll make less power on the same level of boost, and stress the engine more because combustion chamber temperatures will be higher. On the other hand, the more efficient turbo will push more oxygen into the engine at the same boost level because the air charge is more dense (less heat), so more power will be made (assuming ideal combustion in both cases), which could also lead to higher combustion chamber temperatures and pressures.
 
why would the air be hotter from one turbo than the other, if both are at the same pressure? The only thing that will add heat to the charge air aside from the compression will be the increase in entropy resulting from a less efficient compressor. So what this is boiling down to is the fact that a less efficient turbo at xx psi will make less power than a more efficient turbo operating at the same psi. My dad coulda said that, and he doesn't even know what a turbo looks like.
 
Originally posted by MikeBergy@May 5 2004, 11:55 PM
It doesn't care if there is a small turbo or a giant one, psi is psi
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that is where you are wrong. CFM is what matters, NOT psi.

IB, in your article you did state that PSI in the manifold is ALL that matters, and this is incorrect. you proved this in your article by stating that a better manifold will yield more power, given the same PSI in the manifold. its all about the total number of air particles available for combustion.

also, if you are not operating in the efficiency range of a compressor the air WILL be hotter... thats why you cant run a tiny ass turbo maxed out on pressure and expect the charge to be cool. you need to stay in the efficiency range of a turbo and have a proper intercooler setup regardless of what turbo/psi/power you are trying to make.
 
I stand behind my remarks, if you are not operating within the peak efficiency of your turbo, you messed up on building your engine, and it's time to either lower your boost pressure, or get a bigger turbo.
 
Originally posted by MikeBergy@May 6 2004, 01:10 AM
I stand behind my remarks, if you are not operating within the peak efficiency of your turbo, you messed up on building your engine, and it's time to either lower your boost pressure, or get a bigger turbo.
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no one is disputing that fact.
 
well, that is pretty much what the argument developed into; an argument about how to properly size a turbo. I am just saying that turbo size is irrelevant if the turbo you have can supply the pressure you need, at it's peak efficiency. You buy the turbo to meet your expectations, and if you buy a small one, thinking it will make huge power numbers, then you are off your rocker, not you personally, but just people in general. Just because someone knows about a turbo does not make that person capable of engineering a capable system, modifying a system that was systematically designed by intelligent and informed engineers.
 
Originally posted by MikeBergy@May 6 2004, 01:28 AM
Just because someone knows about a turbo does not make that person capable of engineering a capable system, modifying a system that was systematically designed by intelligent and informed engineers.
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ndogg may not be an intelligent informed engineer but he did a damn good job of making his own turbo system
check it out b4 u start disputing his knowledge

http://www.pgmfi.org/twiki/bin/view/Home/NdoggSuccess
 
Originally posted by MikeBergy@May 6 2004, 01:28 AM
well, that is pretty much what the argument developed into; an argument about how to properly size a turbo. I am just saying that turbo size is irrelevant if the turbo you have can supply the pressure you need, at it's peak efficiency. You buy the turbo to meet your expectations, and if you buy a small one, thinking it will make huge power numbers, then you are off your rocker, not you personally, but just people in general. Just because someone knows about a turbo does not make that person capable of engineering a capable system, modifying a system that was systematically designed by intelligent and informed engineers.
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lets say that you are pushing 15 psi on a straight t3 super 60. this may be at the upper end but still on the peak efficency island.

and i am using an sc61 at 15 psi, and this too is on the peak efficiency island.

if you believe that this scenario is possible... are you telling me that you think the motors will get the same power?

the answer is NO because the sc61 is flowing ALOT more CFMs at the same pressure. both are operating in the effeciency islands but the larger turbo flows MORE air at the same pressure level.

so once again... and this is the last time PSI is irrelevent, CFM is what matters.
 
ndogg was not the subject of my rant, in fact he is just supporting the stuff I said, and vice versa.
 
Originally posted by ndogg@May 5 2004, 11:34 PM
lets say that you are pushing 15 psi on a straight t3 super 60. this may be at the upper end but still on the peak efficency island.

and i am using an sc61 at 15 psi, and this too is on the peak efficiency island.

if you believe that this scenario is possible... are you telling me that you think the motors will get the same power?

the answer is NO because the sc61 is flowing ALOT more CFMs at the same pressure. both are operating in the effeciency islands but the larger turbo flows MORE air at the same pressure level.

so once again... and this is the last time PSI is irrelevent, CFM is what matters.
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show me a dyno of YOUR motor, one dyno run of each of these turbos installed on your motor, and maybe I'll believe you. A certain turbocharger is not going to make a difference, the cylinders are going to be filled with air at a certain psi, and cfm is limited by the airflow restrictions in the head. Using the exact same motor, assuming that both turbos are operating at the same efficiency, they will make the same power, laws of TD dictate that. Show me a set of dynosproving otherwise, and I'll step down. Where is loco when you need him?
 
sorry Mike, I'm with everyone else on this one. I've tuned a GSR with a T3, I've tuned a GSR with a holset HX35 (think: SC61) and the boost maps look totally different. The T3 was barely working 450cc injectors@60psi fuel pressure at 10psi. The holset had maxed out the duty cycle of the same injectors, same motor, same manifold, same size DP same everything but the turbo by 8psi.
 
CFM's have nothing to do with power output, that is all I'm saying. 10 psi produced by the compressor is going to yield the same CFM regardless of turbo size. Now, if we are talking about mass flow rate, that will be a different story, A turbo operating at 10psi at 80% efficiency will be pumping cooler, more dense air than a smaller turbo operating at 70% efficiency at the same psi. This translates into more power, because then you can shoot more fuel into the chambers. This is what you were talking about when you said the injectors were maxed out. Bottom line is CFM does not equal power. A bigger turbo does not necessarily mean more power if its efficiency at a certain psi is not higher than a smaller turbo running the same boost. Back to the original topic of this thread, all tuning issues aside, if a motor has been properly tuned, and built to withstand a certain power output, it's not gonna take a dive unless something breaks catastrophically, like a timing belt or something. If a motor is built to make a certain power limit, say 300hp, just don't go above that number, or problems are gonna be coming in the near future. CFM does not = power, nor is it responsible for your engine taking a dive. Intake air temperature, well all I have to say is that the cumbustion temps negate the effects that intake temps might have on the wear and tear of a motor. What kind of temps does the intake charge have? 200F? 250F? The cumbustion temps get get to be like 4000F and higher, depending on CR. Stress from intake temperature is almost a nonissue by comparison. I am done arguing. Give me a couple dyno sheets of a small and a large turbo running the exact same efficiencies at the same psi, same motor. Hell, it makes me want to forget about my NA project, and do this for the sake of pure science. Maybe even a senior project or something.
 
the T3 was closer to its efficiency island than the HX35 at 8psi. Why did the holset make more power (as evidenced by the fueling implying AFR implying more air) than the T3 if the T3 was more in its island?
 
Originally posted by Import Builders+-->
Import Builders) said:
all I have is one thing to say, because its obvious I can't change some people's minds on many topics.
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You lack reading comprehension, or you're talking to the stunnas, bro. Everything I say is exactly what I mean... if you need clarification, I am more than happy to provide it, but I am entirely correct in my statements. I just want to make sure we are having the conversation I think we are having.



Originally posted by Import Builders+-->
Import Builders) said:
Whoever says, and I mean whoever...that using a smaller turbo and boosting more to make 300 WHP is better than using a larger turbo boosting less and making 300 WHP is better is flat out:

insane. and wrong. ( no offense guys)
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I never said anything about turbo size. I was talking flow, case in point headflow, and how it affects boost pressure vs power output and their ties to engine longevity.



Originally posted by Import Builders

And the motor boosting higher is wearing more than the motor boosting less making THE SAME POWER>

BECAUSE:

It generates more HEAT. Heat causes wear, big time.

So I conclude, that a motor making 375 WHP with 10 PSI is wearing less and lasting longer than another motor making ONLY 300 WHP boosting 15 PSI.

(at the same compression level) we are talking about using the same pistons in both motors.
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Lets level the playing field with your example, and say both engines are making 300 whp... the first engine at 10 psi, and the second engine at 15 psi. All else about the engines and their setups remaining equal as you stated; compression level, manifold selection, turbo selection, etc.

Now.

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.
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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.
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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
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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.
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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.
 
Damn... calm down, then get off your ass and take a few years of engineering thermo / fluids / heat transfer classes at a top 10 university.

Your stuff isn't 100% correct either.
 
Well, you're right my tone is out of line. Poor excuse, I get cranky when I haven't slept.

I'd appreciate you picking holes in anything I've said that is not wholly correct.
 
Damn... I don't know what to say here. I really don't know a whole lot about boosting. But I do know when someone is getting out of line. You may be right, but you're being a dickhead. I don't care if you haven't slept or if your boyfriend wasn't considerate enough to give you a reacharound, don't act like that. Calling someone like Jeff a stunna is fucking uncalled for. Where is your record-setting engine building company, fuckstain? Yeah. Eat a bowl of dicks and wash it down with a tall, steaming glass of butt mud.
 
i would like to thank j davis for clearing this thread up.

everyone who posted in this thread just got schooled. we should all be thanking joseph, not bitching about him being a dick [which most people think he is]. ;)

btw, what records is IB homie breaking?
 
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