http://cgi.ebay.com/ebaymotors/ws/eB...tem=2425545011

I thought a T04R is the same as a T04S?

 

Its not quite as big as the t78.

 

Thats what I had thought myself.

 

Its pretty close though

 

Nope, T04R is just as big as T78.

See www.moreboost.org
Both are 66-67mm turbos good for 700 rwhp.
T04S on the other hand is a 60 mm turbo.

 

Is the T04R a garret turbo that will fit on a standard T04 manifold? Or is it an HKS turbo of some sort?

 

T04r is a HKS, T66 is a garret

 

Wheel size is listed as a trim meaning a ratio of inducer AND exducer. Simply looking at the wheel inducer doesnt mean SQUAT. If you look at your own referenc the T78 has a 90mm major diameter and the T04R has a 84mm major diameter. Pretty big difference!! Theoredically sense the T78 and T04R has simular inducer diameters but the T78 has a larger exducer it should develope boost faster and its efficiency should be better in the higher psi range, conversly the T04R should make boost a little later but be more efficient in lower boost range compaired to the T78. This is theoredical though, as practice always differs. AND YES I said the larger wheel making boost first, why..... Blade tip speed, both wheels spinning the same rpm the larger wheel has a higher tip speed, also do to the extra tip speed higher boost usually is better. Lag or turbo spool is mostly a result do to inducer size (larger inducer has to swallow more air per revolution ) only speaking in compressor side that is.... But like I said, theory, I have no experiance with either wheel and also when your talking wheels this size inertia plays a role more then the "smaller" compressors.

Not much of a contrabution to the thread, but i hope I clear up some missconseption about these "BUZZ" words people like to throw around which just confusses people that are not so familiar with turbo chargers and the lingo. Also, compairing wheel diameters gets you in the ball park and an idea of what a compressor is capable of, but there are other factors, one is B-width (the blade tip hight at the major dia), also aero dynamic factors. Compressor housings also play a role on how a turbo responds. btw ignore my horrible spelling, im at work and in a hurry :P

~Mike...........

 

since ive had both turbos i can tell you that the T-78 is bigger than the T04R, without a doubt...as said above the exducer on the T-78 is much bigger.. the turbine on the T04R cutback is tiny compared to the Mitsu T-78


Steve

 

Of course Steve,

It is a 0.84 A/R compared to the 1.15(?) of the T78. Yes, I was only comparing inducer because that's where most of the differences of power are made. Doesn't mean SQUAT ? Try T51R KAI with 70 mm inducer and T51RSPL with 76 mm inducer, one produces 800 rwhp with ~80 lbs/min the other almost 1000 RWHP with ~95 lb/min. And I'm interested in your theory of larger exducer size helps with lag. If that is the case, we would see a huge number of turbos with as large exducer wheel as possible and as little trim as possible. For example two turbos : one has 66 mm inducer and the other has 66 mm inducer as well, but instead of 84 mm exducer the other has 150 mm exducer. Hooo... I guess the 150 mm exducer turbo will kick *** isn't it ? Maybe we don't need ball bearing units after all.
I do agree with the fact that larger exducer is more efficient at higher boost.
THAT'S WHY we have smaller trims turbo of the same exducer size : flow less but faster response and high efficiency at high boost.

If you look above you where this discussion started, it's obvious we're talking about potential for power. As you said, it gets you in the ballpark and that's what I'm trying to do in 3 short lines of my reply. It's true I don't explain much in the beginning for people who are not so familiar with turbos, but I have found that most people aren't so inclined to learn the technical aspects of pretty much anything. Until they asked the right questions and shows a lot of interest then we can have a technical discussion going.

 

Oh I meant the rest of the reply in response to Mike btw...

 

screw it...just get a T51SPL it is awsome up top....and gettin itthere ain't that bad.

 

First off, I'm NOT a turbo expert, the word "EXPERT" implies I make a living dealing with turbos. BUT, I have researched the subject intensly and have been around internal combustion engines quite a bit. Also, I work with (I work at NASA) a lot of "experts" in the fliud, aero, and thermal dynamic fields.


QUOTE: {I'm interested in your theory of larger exducer size helps with lag. If that is the case, we would see a huge number of turbos with as large exducer wheel as possible and as little trim as possible. For example two turbos : one has 66 mm inducer and the other has 66 mm inducer as well, but instead of 84 mm exducer the other has 150 mm exducer. Hooo... I guess the 150 mm exducer turbo will kick *** isn't it ? Maybe we don't need ball bearing units after all.}

First off, its NOT my theory, its common turbo knowledge. My THEORY in the post was more specific, being the t78 (only compairing compressors, not the whole turbo charger) would produce boost spinning at same rpm before the to4r and be more efficient at higher boost ratios. AND, I also said that this works less effectivly ( the larger exducer vs. smaller with same inducer)with the larger turbos. QUOTE: {when your talking wheels this size inertia plays a role more then the "smaller" compressors.
} . And ABSOLUTELY YES equal inducer turbos spinning same rpm the one with the larger exducer will be making more boost. Like every thing car / engine related it only works in moderation, unlike your sarcastic reply on the matter QUOTE:{one has 66 mm inducer and the other has 66 mm inducer as well, but instead of 84 mm exducer the other has 150 mm exducer. Hooo... I guess the 150 mm exducer turbo will kick *** isn't it ? Maybe we don't need ball bearing units after all.
} you seem intelligent but that was plain sarcasm directed at me because something was written YOU dont understand. ITS VERY common for "turbo" upgrades that are a mild upgrade from stock to have a larger inducer, this inhales more air ..... well to offset the induced lag do to the larger inducer, turbo people (at least one's who know what their doing) will ALSO "up-size" the exducer also to speed up the boost response so you get almost stock like response but good top end to boot. Again, this works in moderation as most things, HUGE ports sometimes makes less hp then smaller, smaller intake, and or exhaust sometimes will make more hp then huge.. really big wheels and / or rear end gearing will give you faster top end, but sometimes you can go to big and the smaller ratio yeilds fatser......etc, you get the point i hope.

And YES inducer diameters is a good indication of a turbos hp output, but doesnt tell "SQUAT" about how a turbo responds at all. what good is a turbo capable of 700hp that wont spool till 9k rpms? I don't want this to be a flame, I didnt make any flames in my original post........

~Mike.............

btw, I do 100% agree that sometimes a 3 liner is more appropriet, like you said most pepole dont care how things work, they just want to buy and bolt it on......

 

Well, I still don't understand...

What you said was very specific. Larger size exducer on same size inducer on two turbos will help turbo lag.

And from here I deducted that there is an optimization point for every inducer size, right ? Say there is a point of diminishing returns on how far to go larger on exducer size given an inducer size, right ? If that is so, then what's the point of having different trims turbo. Garrett, Mitsubishi, IHI, and who knows else that spent
big $$$ will only be making same trim turbo for a given inducer size.
Your logic about can't go too big, smaller ratio yields faster, etc works in certain situations but definitely not here. It's like Master Yoda saying "size does not matter" to a couple of sex-crazed **** queens.

And I find it hard to believe somebody who work with a lot of people at NASA in fluid, aero, thermal dynamic fields couldn't produce any scientific proof, back up any claims about their argument. Show me a piece of scientific article about what you're talking about. For all I know, you could be a receptionist at NASA HQ, or an accountant at Cummins for being around internal combustion engines quite a bit. And don't say it's common turbo knowledge either. If it's so common, it would be written everywhere at Turbonetics, Innovative Turbo, and most other turbo manufacturer's website. I don't care if you're Einstein himself, give me some something concrete. Again, as you said in your post it's not a flame.

You complained about my sarcasm earlier and here you are, you should take your own advice. Look in www.t04r.com, you can see dynosheets of both T78 and T04R. They're similarly matched.

 

Got yeah,

But I still don't understand why you don't get it, a larger wheel spinning the same speed as a smaller wheel will have a faster tip speed. Tip speed flings the air off faster = more air movement...There are also sooo many factors as to why there are different level trims, pressure ratio being the biggy. Also, all engines are different and turbo manufactures have to make a wide range of turbo chargers (diesal, 3 cyl gas, etc. etc.). I'll bring in all the articles I can find tomorrow if I remeber and quote it. I do however remeber specifically which mags and books this EXACT convo pertains to, Turbo, Sport Compact Car, Nitrous and Induction Systems, Corky Bell's "Maximum boost" etc.... all have this in there. And I am a mechanical engineer, I do more specifically at work: machinist, mechanical CAD drawing, wireing, board population, I take car of all the air frames which includes making them from scratch and designing air craft from scratch, I maintain them, I fly them (Im talking about UAV's {Unmanned Air Vehicles})....... but my love is tinkering with **** and making it faster / more efficient. I do have a lot of aero background as well, but I have never finished college, all my work and refferences are based on experiance and what schooling i did finish.

So wait till i bring in info or better yet find it your self so I'm not accussed of "making chit up" or miss-quoting magizine articles / books.

~Mike..........

 

QUOTE{ Your logic about can't go too big, smaller ratio yields faster, etc works in certain situations but definitely not here. It's like Master Yoda saying "size does not matter" to a couple of sex-crazed **** queens.
}

My logic here applies 100% whens the last time you saw a 30 trim, or even a 90 trim????? YOU HAVENT cause those are to either end of the extremes. I mad this analogy QUOTE{ITS VERY common for "turbo" upgrades that are a mild upgrade from stock to have a larger inducer, this inhales more air ..... well to offset the induced lag do to the larger inducer, turbo people (at least one's who know what their doing) will ALSO "up-size" the exducer also to speed up the boost response so you get almost stock like response but good top end to boot. Again, this works in moderation as most things, HUGE ports sometimes makes less hp then smaller, smaller intake, and or exhaust sometimes will make more hp then huge.. really big wheels and / or rear end gearing will give you faster top end, but sometimes you can go to big and the smaller ratio yeilds fatser......etc, you get the point i hope.} in response to this.........QUOTE{And I'm interested in your theory of larger exducer size helps with lag. If that is the case, we would see a huge number of turbos with as large exducer wheel as possible and as little trim as possible. For example two turbos : one has 66 mm inducer and the other has 66 mm inducer as well, but instead of 84 mm exducer the other has 150 mm exducer. Hooo... I guess the 150 mm exducer turbo will kick *** isn't it ? Maybe we don't need ball bearing units after all.
}

~Mike.........

 

well, I actually remembered to bring in what I have. I'm amazed that I recall this info from back in 95. (yeah, thats how long I been researching turbo charging).

I'll start off with an isssue of Turbo Magizine Sept. 1995 (yeah old but informative, not a whole lot has changed in turbo basics). Article tittled "Mama Always Told Me, You Better Stay In Spool!" ( Just have to throw in how ironic this tittle is in how this partaines to this thread..lol). The article is compossed of info credit given to Turbonetics, and Innovative Turbo.

QUOTE, page 99 subtittle, Exducer:

"At Turbonetics, (OHH LOOKY HERE... TURBONETICS INFO) they refer to the outside of the compressor wheel as the exducer. This is the portion of the wheel which directs airflow into the compressor housing. When the exducer diameter is increased, a radically different effect is produced. Whereas an increase in the compressor wheel's inducer increases turbo lag, an increase in the exducer of the wheel can actually reduce turbo lag. To understand this, one must first understand the function of the compressor wheel as a whole. the compressor wheel functions by inducing air axially and then "slinging out" the air radially. Thus, increasing the exducer diameter increases the outside diameter of the wheel. This increases wheel's tip speed for a given shaft rpm. As a result, a greater slinging action is imparted to the air coming off of the wheel. The end result of a larger exducer is that it will cause a compressor to produce a higher pressure ratio than an smaller exducer wheel at the same rpm. The lesson here is that a compressor wheel can be selected where a large diameter exducer can be used to offset the short comings of a large diameter inducer."

More over, next article from same mag, paragraph intittled "Performance Improvements":

"For anyone needing quicker then-stock response from their turbo, the solution is simple. Maintain the same size inducer and increase the exducer of the compressor wheel. Sinse the turbine side remains unmodified, the newly selected compressor wheel will be driven at approximately the same speed as the original wheel. This results in a quicker boost curve giving impressive "seat of the pants" acceleration.
Now lets say that you are happy with your current turbo response and you would be willing, in some cases, to trade off a little of your response for an increase in top-end power. In this case a larger version of your current wheel may be in order. the increase in inducer size will generate the high-digit horsepower while the increase of the compressor wheel's exducer will offset some or all of the increased turbo lag brought about by the larger inducer. Many so called "sport" turbo's feature this style modification."

I think I gotten my point accross, but heres more.......
In the same mag, same article, same page, theres a picture of two compressor wheels. On the left a H-Trim (2.298" inducer, 2.75" exducer) and on the right a Super H-trim (same 2.298" inducer but with a 3" exducer) the caption is as follows:

QUOTE{ Here is an example of an increase made to the compressor wheel's exducer (od). On the left is a standard H-Trim compressor wheel with a 2.75-inch exducer. On the right is a "Super" H-Trim wheel unique to Turbonetics, with a larger 3-inch exducer. The overall effect of this upgrade is a reduction in the amount of time needed to spool the turbo. Sinse the contour and inducer of both wheels is identical, the "Super" H-Trim will fit into any standard H-Trim housing."}

All this from one magizine that has its info from Turbonetics and Innovative. I have more articles and books supporting this, but this seems sufficient to me. I hope anyone reading this gains further turbo charging knowledge and can be more confident in the decisions made by them and or info or recommendations made by turbo experts when desigining their turbo system.

~Mike..........

 

Hahaha.. what I don't get is how do you assume right away that the two will spin at the same speed ? That has been my whole point at the last post.

You mentioned inertia in your earlier posts. Do you know what that means and how to calculate them ? It's a quadratic relationship relative to distance from the center if I still remember high school physics. You know what that means right ? You've seen Michelle Kwan skates ? Hope you get the picture there.
The first article sourced from Turbonetics you claimed, specifically mentioned that

... for a given shaft rpm. BTW, please do this quoting from now on. I'm getting dizzy trying to read your posts.


BTW, give some more credence to your supporting documents. Since you obviously still have a copy of it, scan the damn thing and post it. Or find somewhere else in the internet that supports your claim. What you had just typed is a far cry from what I expected from a guy who "worked with a lot of NASA people at aero, thermal, fluid mechanics". And you know what ? People who writes articles aren't always right. Please give some more data and supporting documents to answer my questions :

1. Why are compressor trims even existed. If you theory holds true, for every inducer size there is only one optimized exducer size.

2. Why is the turbo with the larger exducer spins the same speed as the other while its inertia and rotational weight clearly indicates otherwise ?

3. Closely related/proof to no. 1, why is T76 turbo ever existed ? It has the same size exducer size as T72, larger inducer, flows more at the expense of more lag. If what you said is true, Turbonetics and/or Garrett would have compensated the increased inducer size with larger exducer to help with lag, right ? So in reality, all turbos from as small as apple to as large as a watermelon will have roughly the same lag(or if it's not a linear relationship, it must follow a certain trend).
Mind sharing with us what the trend is ?


Please address these points. In your first post, you make a claim which was somebody else's, instead of quoting it. That's a big statement and I hope you can back it up.

 

My buddy has been trying to rebuild his Harley engine for 3 yrs all himself to no avail cause he doesn't have the correct resources and didn't understand basic engine tear down. I showed up for a couple of weekends with the right shop manual and tools and get the job done w/ him.

If you've done 8 yrs of research about turbochargers, you'd be speaking "thermodynamic greek" about this topic by now such as supersonic flow, boundary layer separation, oblique shocks, rotating stall, slip factor, isentropic, air bleed, etc.
I know because my girlfriend took turbomachinery class at Purdue not too long ago... she was depressed because of that.

 

Go to www.moreboost.org , and TO4r.com. Real world the TO4R, and the T78 produce similar #s with similar spool. Do we care about the theory? Only if it allows us to buy one turbo instead of six to get to our intended result I say you guys go out back, and bang your heads together until only one is conscious. The unconscious person wins, as he no longer cares about the theory. We are users, not designers, we take no joy in theory, only results, and the results are essentially the same. Carl

 

Carl,

That was what I was trying to say, right ? That they're both very similar. I also posted the exact same websites as you did in my earlier posts. Don't get me wrong, from the very start I don't want to get into these technical details hence my short reply.

You may take no joy in theory, but other people might. And I certainly want to know more about turbos and realized that there are other people willing to share their knowledge. And if there is no theory, you wouldn't have any turbos worth your money out there.

 

Eric has a good point in that last post. If there weren't some real "techies" out there then turbos would never evolve into better, stronger, and faster spooling units than what we had 10 years ago. Has anyone had any experience with A-Spec Tuning's new T04R BB unit?? I'm very curious as to how much faster it will spool than the regular T04R??

Zach