alright my dad is one of those people that likes horse power but doesnt like after market parts anyways he is trying to tell me that a huge turbo like a gt35r at 5psi is the same as 5psi from like a t25. i have tried explaining to him that a larger turbo puts out a greater volume of air even though still at 5 psi and have tried all different types of examples like tire pressures and blowing through straws and he just say BS 5psi is 5psi no matter what turbo and that the only point of a bigger turbo is for more boost.... i dont care about efficiencys at what rpm or rite size turbo on what motor just plane and simple why a larger turbo at 5psi makes more power than a small turbo at 5psi.... oh and he said the waste gate will not let the larger turbo build anymore volume.... pretty much he doesnt under stand why a larger turbo makes more power at the same psi than a smaller turbo

 

And, what's your point?

Just cause it's a bigger turbo/makes more power at a given PSI doesn't mean it will have a better powerband than a smaller turbo. Evans Tuning showed a MASSIVE mid-range power increase going down from a GT30 to a GT2971RS on a D16. Peak power was the same. PSI might have been different, but it made damn more power in the midrange, which is where you spend most of your time.

Honda people have been tricked into thinking only peak HP matters.
But you have another 6000rpm+ of rpm range to use.

 

doesnt it say im not talking about any turbo on any motor? ya thought so....

im asking why a bigger turbo is CAPABLE of making more power than a small turbo....not talking about any given motor just the turbo in general

 

what really matters is the displacement of the motor... without taking that into account both your dads and your points are moot... turbo's all run from air getting pushed through the turbine (as we all know), the larger the turbo, the more air is required to spin said turbo, and the more air the compressor can put out... but i must agree with him, a wg set at 5lbs for both will only provide 5lbs, the only difference will be how long it takes to reach said pressure

 

ya it will only hit 5psi no matter what turbo but why will the larger turbo be capable of making more horse power at 5psi?.

 

good discussion here

http://www.team-integra.net/forum/di...TopicID=255321

 

thanks this helped a lot

 

this isn't just a rant we were having a conversation about something and i said something and he said i was wrong and we started arguing about it. i would never ask a question like this on honda tech. i would read and learn about it as much as i could cause i love reading and learning more about cars. but my dad was like i see you are always on honda tech reading about anything and everything so post it on their and see what they have to say. so i did.

and yes that is more than i was asking before but either way like i said before i love reading and learning. so either way your posting did what it was supposed to do an educated some one and i thank you for taking your time and posting what you did.

to make my question simpler here is an example. take 2 b18a's that are bone stock put a T3/T4 57trim on 10psi and make 250whp then put a t3/t04e .63 ar on the other on 10psi and make 300whp he doesn't under stand why one would have more power cause their on the same amount of boost

 

Didn't endyn have 113% ve motor?

 

whats a ve motor????

 

Simple explanation: Pressure does not equal flow. Think of two pipes; both are flowing water at 5psi, one is 1" diameter, the other 10" diameter. Which is going to move more water?

Or, two fans (which is more relevant). You can run two fans at the same pressure (5psi); a 12" can do 30cfm and a 60" can do 150cfm. The 60" fan has a larger inlet area, and therefore is capable of more cfm at the same pressure level. PSI=pressure, CFM=volume.

VE means Volumetric Efficiency. The only way a motor can have 100% or better VE is through forced induction.

 

In the discussion of VE, you can't ignore the biggest factor which affects VE on a turbocharged engine aka exhaust flow.

Exhaust pressures, exhaust flow is directly related to turbine sizing. Turbine sizing has the biggest effect on volumetric efficiency.

If exhaust can't get out, then how could fresh air go in?

Compressor efficiency, air temps and so forth is really miniscule when discussing about the gains from a bigger turbo.

You can run a huge 80mm compressor wheel and up the boost to 20 PSI with air temps equal to ambient and an unrealistic compressor efficiency of 100%, but you aren't going to make more than 180 WHP on a B18 if you had a GT15 turbine wheel and a 0.48 a/r turbine housing on there.

5 PSI can never be the same as 5 PSI on a different sized turbine.

Hey ScorpionT, Formula One engines have already surpassed 100% VE in naturally aspirated form, and it's on gasoline.. This was from quite a few years ago too

 

this is true, but you also have to remember bernoulli's principle... when air/fluid enter a restriction at a given pressure, velocity will increase... so not only does it depend on the size of the turbine/compressor but also the size of the intercooler/piping... bigger pipes can mean bigger potential for a loss of pressure

 

Very true on the turbine wheel doing most of the work obviously affecting how the compressor wheel reacts but you have to take into account that compressor and turbine wheels are designed to complement one another. Since turbo manufactures don't release turbine wheel maps you can't exactly accurately match one to an engine simply look at the compressor wheel maps. If you are to close to the surge point of that particular map you need to step up the A/R.

Also, it was me that claimed the none 100% V.E. n/a engine. So if that is the case than I stand corrected. Although I fail to see how you could do that without the use of forced induction?

 

trying to remember the exacts on how they did it, i know exhaust scavenging played a big part in being NA over 100%

 

I did try address that point slightly but I think in some of my explaination I skipped over some stuff or didnt really explain it well after I re-read my post. Your statement isn't necessarily accurate that the larger turbo would make better power at that particular boost pressure. You need to first do several calcuations to figure out the N/A V.E. of the engine in question. You then need to pick the possible boost pressures you would like to run and do calcuations according to what RPM ranges you would like to see full boost at. You then plot your calcuations on what is known as a "compressor map" Depending on the A/R of the turbo, the trim, and at what range that turbo is most efficent will determine which engine will make more power. You cannot think of it at what is the peak power you need to see a smooth and relatively straight line for where you're seeking the power (what RPM range). As in you would like to see full boost by 5000RPM and want that turbo to remain as efficent as possible all the way until 9000RPM. It's not quite as simple as Bigger turbo = more power cause that isn't always the case.

 

I know they actually design alot of scavaging effects into stock vehicles, we learned alot about that in our engines lectures. I'll try to do some research but I could of sworn I remember being told that there wasnt a 100% efficent engine.

 

^^The engine isn't 100% efficient...it has over 100% volumetric efficiency. Search and you'll understand what the difference means

 

 

hahah I can hear TheShodan laughing at the newbie responses and comments from here....

 

Good point, but I was referring to street cars. Pulse tuned $2mil engines are an interesting exception :D

Speaking strictly about the compressor side with no factors. I could really go into details, but I didnt want to confuse the OP or his father.

Not with normal designs/methods, it cant happen. Sonic pulse tuned intake manifolds arent going to be on the street anytime soon.

 

that's just because he knows the answers to what we've been probing in the dark about

 

I found it easier to grasp by thinkin of air inside a box. A 1ft^ box with 5 psi inside and a 2ft^ box with psi. The 2 ft box has twice the amount of air because it has twice the amount of space at the same psi. With that said a turbo with a .50 ar and one with 1.01 ar the bigger one will flow more air at the same psi. You could also think of an air compressor tank a 5 gallon at 100psi will run out of air faster than a 10 gallon tank at 100 psi just because theirs less air. Hope that helped.

 

think most of us have experienced this with air tools

put an impact on a construction pancake compressor......it's powerless even at 100psi

put it on a 120 gallon ingersol shop compressor and it will break bolts at the same 100psi

 

Good thread..... waiting for shodans input