looking for 300+ hp

[Joseph Davis]

I don't doubt IB's ability to build an engine - hard to go wrong when you use quality parts and recommend quality engine management solutions. As I stated earlier, in a very poor fashion, IB is confusing the results of balanced flow through the engine and proper tuning and the nature of cfm/heat/energy with the tenuous relationship he has noticed between the high hp/low psi and high psi/low hp setups. High hp/low boost setups typically use the good turbo manifolds with properly designed collectors (see mine below) that help promote balanced flow and thus even out AFR in individual cylinders. The "same engine" that produces poorer hp at high boost doesn't, and even if your average AFR via wideband is correct, you have variances in the cfm through each cylinder that results in one cyl going lean and shitting itself.

I prefer to boil it down to a "poorer" flowing head; LS vs VTEC as the case may be. If you ensure the flow through the head is balanced, is the higher pressure differential significant to engine longevity? No.


Anyway, here's my mani/turbo:

You'll notice it's very similar to this manifold, which holds an interesting record of sorts, don't know if it's been broken yet:

It got bolted to this stock GSR engine with a SC34:

Damn if it didn't make 251 whp at 5.1 psi, that's 100 up from a stock GSR whp. 20 hp/psi is pretty nice. Todd who built the manifold decided to do the same for himself, only use an SC61:

I'm very conscious of flow through a turbo system - I cut my teeth on setups like the ones, plural, above. Thanks to radnulb for setting up pgmfi.org, I am very conscious of exactly how ECUs and speed density EFI behaves. I am very certain of my knowledge, and am looking forward to criticism of it.

BTW, I'm not interested in building engines, dohch22a4, because a street Honda doesn't need anything more than a stock engine to hit it's traction limit of 300-350 whp. Any more than that is wheelspin until 100, and you have no place doing over 100 on public roads.

 

[phunky.buddha]

Originally posted by Joseph Davis+May 7 2004, 05:09 AM-->

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.

I don't really want to take the time to pick holes through anybody's stuff in this thread anymore. It's become a flame fest, and I don't want to add to it. No matter what I say, someone's going to say "you're wrong, you're a retard, this is how it should be." I know my thermo/fluid/heat dynamics well enough to know what I need to know about simple turbocharger systems.

Joseph Davis@May 7 2004, 04:45 AM
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.

Simple stuff first:

PV = nRT

P = pressure
V = volume
n = moles of substance
R = some thermo constant... 8.314 kJ/(kmol*K)
T = temperature

You're curious about T, so you move some stuff around and get this equivalent:

T = (PV)/(nR)

You're making the same amount of power on both your 10psi and 15psi setups, so assuming ideal combustion (all molecules of O2 and fuel are burned), that means that you have the same number of oxygen molecules in both intake charges.

n @ 10psi = n @ 15psi.

R is the same at both pressures because it's just a thermodynamic constant.

V is the same at both pressures because it's the physical volume of your intake manifold.

You cancel out V, n and R because they're the same between both equations, and you're left with:

T = P

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


To prove further...

Let's look at work done to compress a charge of air- purely conceptual, no math. You have two equal volumes of air, but one is at 10psig and one is at 15psig. Both containers started at 0psig. To pump both identical containers up to 10psig takes the same amount of work. To take one even fartherto 15psig takes more work. If you do more work, then you're adding more energy into the system. More energy in this case means more excited molecules, which equals heat. The higher pressure system will be hotter, even if both compressors are operating in their ideal efficiency range.

At the same power output with everything else identical, the engine with more pressure in the intake manifold will have more heat going in, a higher chance of detonation, and therefore have more wear on the engine etc... it may not matter when everything is still behaving, and it may all wash out in the end when you start factoring in all the different variables that you can never keep the same- but the facts are still the same.

I'd throw some p/v diagrams and all that wonderful stuff up here, but I really don't want to take any more time to screw around with this crap. Pay me some engineering consulting time and maybe I will...

 

[MugenCRX]

I know nothing about turbocharging.




Now that that is out in the open, I'd have to say that this is the best thread that I have read in a long time, mabey even the best ever. It is 3 pages of long, very technical posts and took about an hour for me to go through, and try to understand what is being said and whats going on. I'm sure I have learned something, I'm just not sure what it is yet. But... From what I have read this is how I see it.(and dont flame me for what I say, I'm just simply asking if I understand)

All mathematical equations aside(I have no Idea what I'm about to say, but here goes)

Two motors, equal in all aspects except turbo size.
Motor A makes 300hp at 10psi with a larger turbo. Larger flow rate = Same pressure in combustion chamber under less psi.
Motor B makes 300hp at 15psi with a smaller turbo. Smaller flow rate = Same pressure in combustion chamber under more psi.
We are wondering INITIALLY which motor will last longer right?
Ok, from the knowledge I have gathered, the more pressure in the combustion chamber, the higher the temperature in the combustion chamber, right?
And if were talking about the bottom end internals being the reason for the breakdown of the motor, that is where the aspects of wear and tear are going to be focused.
If all said here is true, then Motor A, I THINK will be the one that lasts longer.
Why?
If Motor A uses less boost pressure with a larger turbo, and vice-versa, wouldnt the pressure in the combustion chamber still end up being equal?
But since Motor B is INITIALLY using more boost pressure to get the same combustion chamber pressure because of a lower flow rate , the molecules will have a higher temp than Motor A when entering the combustion chamber. Therefor Having a higher temperature would = More wear and tear.

Please correct me(nicely) if I'm mistaken, but this is how I took things.

Keep the information coming.

"Oh this learning, what a thing it is." -William Shakespeare

 

[spectacle]

Originally posted by R.E.Developement@Apr 15 2004, 04:54 PM
hay i got a 92 civic si with a gsr in it i also have a small turbo steup for it but dont have injecters or fuel pump yetif my goal is to get 300 hp max what size injecters should i use and i know that ill need a fuel pump and some what type of fuel tuning device such as a vafc.

help me out. thanx

way to go off topic guys. lol good shit

 

[phunky.buddha]

Originally posted by MugenCRX+May 7 2004, 06:25 PM-->

Ok, from the knowledge I have gathered, the more pressure in the combustion chamber, the higher the temperature in the combustion chamber, right?

Generally yes, but that's not always the case. If all other factors are kept equal except for boost pressure, then yes- more pressure = more heat because the compressor did more work to get it in there.

Originally posted by MugenCRX@May 7 2004, 06:25 PM
If Motor A uses less boost pressure with a larger turbo, and vice-versa, wouldnt the pressure in the combustion chamber still end up being equal?

Yes and no.

The pressure after combustion will be the same because it's the same amount of power, but the pressure before ignition will be different because the hotter less dense has to be under more pressure in order to fit more oxygen into the same physical space as the colder more dense air.

spectacle@May 7 2004, 07:46 PM
way to go off topic guys. lol good shit

 

[spectacle]

Originally posted by Calesta+May 8 2004, 01:00 AM-->

spectacle

@May 7 2004, 07:46 PM
way to go off topic guys. lol good shit

yea but you gotta admit you guys took this thread to a whole nother level when all the guy needed to know was what size injectors to run lol. instead you took everybody in a crash course in thermal dynamics and shit. nevertheless this has been an informative, yet entertaining read.

 

[Import Builders]

from dynoing thousands of cars, which only probably 500 of which were turbo, I can come to this observation.

I only have 91 octane. remember that. All these cars do.

Why is it, I can make 400 WHP on a larger turbo, on 91 octane at like 13 PSI, but with a smaller turbo, I can't make even 360 WHP without race gas because when the boost gets up around 14-15 PSI, even with 15 degrees timing taken out, it still detonates?

The reason is, the motor with the larger turbo is way more effecient, and it runs cooler at less boost.

So I don't agree that more boost with smaller turbo is just as reliable as the motor with more boost. There is NO WAY it is.

Because if it was, I could make the same WHP on the SAME octane and according to the combustion heat camp, it would be equal because power is power right.

Thats not true. Tell me why the 400 WHP car runs on 91 with no detonation, and the 360 WHP car with smaller turbo doesn't and if I boosted it up to make 400 WHP the motor would melt.

So as long as there is no explanation besides the obvious (WAY MORE HEAT FROM WAY MORE BOOST, and a combination of other factors, of course) the bigger turbo is more reliable.

This guy Jospeh Davis or whatever made a few good points. But I stated in my article "everything being equal" Saying same manifold, IM, etc. Just a different turbo. The smaller turbo cannot make the same WHP as the larger one on the same octane. THUS its not as reliable overall.

I think the point Davis forgot to make because he was obsesed with hating me, was that the smaller turbo flows say 44lbs/min and the larger one does 62lbs/minute. Thats not equal. I think he needs to go to a dyno, or better yet, own one for 3+ years so he can see, he can do all the math he wants and call me a fucking prick or whatever until kingdom come, but until he sees that he can't make the same maximum HP potential with the smaller turbo compared to the larger, he will never undertsand.

I make 400 WHp without detonating with the large turbo. I take that off, I put on smaller and I make less and detonate. I don't need to be a proclaimed rocket scientist to know its generating way more heat.

You talk like I don't have EGT gauages and widebands hooked up to the car on my dyno, I used for years. haha. Maybe this guy is really pissed at me. I wonder if he would talk like this to me if he met me. I wonder.

I can argue all nite guys. And its early!

haha.

Jeff

 

[saturn_boy96]

this thread is why i want to be an engineer.

nice work Calesta

 

[Import Builders]

also, Davis, your spreading more misinformation. haha (jokes) don't get pissed.

The real limit to a street cars WHY is more in upwards of 450 + WHP.

Its called a boost controller. They are pretty good nowadays. I seem to have built a few turbo motors through my shop in street cars running 11's with ease with full interior. 1 in the mid to low 10's. They all have more WHP than you said wa the maximum.

Go buy some:

BF Goodrich Geforce T/A KD's in 225/50/R16 with a good LSD and corner balanced car and I think youll see 450+ WHP can be had on the street.

I smoked my buddies yamaha R1 in 3rd and fourth gear like nothing. Left him in the DUST. I could see him in rear view mirror before I hit 80 MPH!

If you need any help going faster, or you need parts Joseph, I will help you out. This is a web site to help each other, not hate each other.

jeff

 

[Joseph Davis]

Originally posted by Calesta+-->

Simple stuff first:

PV = nRT

P = pressure
V = volume
n = moles of substance
R = some thermo constant... 8.314 kJ/(kmol*K)
T = temperature

You're curious about T, so you move some stuff around and get this equivalent:

T = (PV)/(nR)

You're making the same amount of power on both your 10psi and 15psi setups, so assuming ideal combustion (all molecules of O2 and fuel are burned), that means that you have the same number of oxygen molecules in both intake charges.

n @ 10psi = n @ 15psi.

R is the same at both pressures because it's just a thermodynamic constant.

V is the same at both pressures because it's the physical volume of your intake manifold.

You cancel out V, n and R because they're the same between both equations, and you're left with:

T = P

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.

Originally posted by Calesta
I'd throw some p/v diagrams and all that wonderful stuff up here,

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

Calesta@
but I really don't want to take any more time to screw around with this crap. Pay me some engineering consulting time and maybe I will...

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

Import Builders
This guy Jospeh Davis or whatever made a few good points. But I stated in my article "everything being equal" Saying same manifold, IM, etc. Just a different turbo. The smaller turbo cannot make the same WHP as the larger one on the same octane. THUS its not as reliable overall.

My example was for a fixed size turbo, and varying headflow, to demonstrate the irrelevancy of boost numbers and illustrate why you have to look at the total system's dynamics. I hate it when I see someone try to quantify boost pressures as a sign of anything, without taking the whole system into account.

 

[Import Builders]

ok fixed turbo size. I was talking 2 sizes. We are talking abotu different things. Ok how about I agree with you on fixed turbo size.

haha, what a mess.

Jeff

 

[Joseph Davis]

Originally posted by Import Builders+May 8 2004, 01:43 AM-->Import Builders
also, Davis, your spreading more misinformation. haha (jokes) don't get pissed.

The real limit to a street cars WHY is more in upwards of 450 + WHP.

Its called a boost controller. They are pretty good nowadays. I seem to have built a few turbo motors through my shop in street cars running 11's with ease with full interior. 1 in the mid to low 10's. They all have more WHP than you said wa the maximum.

Uhm, stunna? I said 300-350 whp was all you could lay down up to 100 mph on the street. Reread that bit.

 

[Joseph Davis]

Originally posted by Import Builders
ok fixed turbo size. I was talking 2 sizes. We are talking abotu different things. Ok how about I agree with you on fixed turbo size.

haha, what a mess.

Jeff

Yeah, a mess. My apology, if it wasn't clearly worded previously, for the manner in which I spoke to you in my past post still stands, if you'll accept it.

 

[MikeBergy]

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

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

Plus, that doesn't take into account the efficiency of the turbine. The lower the efficiency, the more actual work it takes to boost to the same pressure. That is why the air is heated up more by the smaller turbo boosting at the same psi as the bigger one. The smaller one is actually working harder, just more of that work is being converted to heat instead of more pressure. Good info Calesta, takes me back to last quarter. Moving on

 

[MikeBergy]

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.

 

[MikeBergy]

btw, that holset turbo is huge!!! How long does that thing take to spool? What kinda price did you pay on that? Just wondering. And mad props to the guy who fabbed those manifolds. They are very good looking, maybe as good as pro race even.
Carry on.

 

[radnulb]

my homefry had a HX35 on a stock GSR bottom end with ITR cams. 8psi of boost by ~3900RPM at WOT, 3"DP, 2.5" full exhaust, 2.5" Cat

 

[MikeBergy]

Wow, that's good enough for me. How did the ITR cams work for the turbo setup? A 2.5 inch piping setup is prolly a little too small for that turbo. to the 3" dp though.

 

[posol]

Originally posted by MikeBergy@May 6 2004, 08:17 PM
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.

you couldn't be more wrong.

 

[MikeBergy]

Right brian, thanks for proving me wrong. An engine will flow the same cfms at the same rpms regardless of the turbo. Maybe you're thinking of mass flow and getting it confused with cfm.