What trim? What A/R?

[encasemyheart]

I have looked over alot of turbos and finally narrowed it down to a t3/to4e turbo. Stage 3 wheel. I'm trying to decide between a 50 or 60 trim and what A/R to go with.

It is for a KA24DE with final goals of 350-400whp. Which turbo will get me this with the least amount of lag?

I would like to go 50 trim but I'm not sure which would be better, and was thinking .63 or .82 A/R...Any suggestions? I cannot find compressor maps depicting the differences between these so I can't make a logical comparison.

[240zx]

If you want the least amount of lag stick with the .63 exhaust housing. As for the compressor maps here you go.

http://www.turboneticsinc.com/comp_maps/fig1.html

[encasemyheart]

Thanks for the maps, that will help me decide between 50 and 60 trim.

Will a .63 and .82 A/R make a big difference? Or is it a small difference and more like preference?

Time to pull out my old corky bell...

[matt0941]

I have been asking the same questions as I am pretty much in the same boat. From FA someone posted this:

"IMO, the ideal KA-T turbo for street/road course = T3/T04E, 50 Trim, .63 A/R, Stage III exhaust wheel.

Good for 4-25psi on the KA, more efficient than the 57trim across the board.

Quick spool due to the T3 exhaust side, good flow from the T04E compressor. Can support ~380-400rwhp IIRC.

Greaser reccomends it, as do a few of my VERY turbo savvy DSM friends here in town - After looking at my dynos and other S14 dynos, then compressor maps, etc...50 trim was decided as the way to go.

I got the 57 trim (asked too late for reccomendations), wish now I would've gotten the 50, but it will really make a minor difference in my setup considering I'm not looking for +300rwhp.

Later - Brian"

That should give you some confidence.

And what intervals can you choose A/R ratios at, is there nothing between .63 and .82?

Also, what is the main difference between to4e and to4b compressor sections.

[encasemyheart]

You can get any intervals I believe, but usually anything between .63 and .82 is a custom job, those are the most common. Thanks ALOT for the advice, that's exactly what I was looking for.

From what I know the t04b cannot flow as much air so it can't support as much hp. It's supposed to be alot smaller than the t04e.

Do you know anything about the exhaust wheel stages? Most (well, all) that I have seen come with stage III wheels. Do you know the difference?

[WDRacing]

I have been asking the same questions as I am pretty much in the same boat. From FA someone posted this:

"IMO, the ideal KA-T turbo for street/road course = T3/T04E, 50 Trim, .63 A/R, Stage III exhaust wheel.

Good for 4-25psi on the KA, more efficient than the 57trim across the board.

Quick spool due to the T3 exhaust side, good flow from the T04E compressor. Can support ~380-400rwhp IIRC.

Greaser reccomends it, as do a few of my VERY turbo savvy DSM friends here in town - After looking at my dynos and other S14 dynos, then compressor maps, etc...50 trim was decided as the way to go.

I got the 57 trim (asked too late for reccomendations), wish now I would've gotten the 50, but it will really make a minor difference in my setup considering I'm not looking for +300rwhp.

Later - Brian"

That should give you some confidence.

And what intervals can you choose A/R ratios at, is there nothing between .63 and .82?

Also, what is the main difference between to4e and to4b compressor sections.

Good Job Matt...

WD

[C-Kwik]

And what intervals can you choose A/R ratios at, is there nothing between .63 and .82?

Also, what is the main difference between to4e and to4b compressor sections.

A/R's by definition have an infinite number of possibilities. But Turbo manufaturers tend to make only certain ones.

As far as the difference between the TO4 E & B, it comes down to size. The B has a 2.75 inch major(outer) wheel diameter. The E has a 2.95-3.00 inch major diameter. The different trims just account for the minor(inner) diameter. All the T04E has a 2.95 inch major dimater while the T04E 50 Trim is the only one that has a 3 inch outer diameter. The Super T04E series has a 3.20 inch major diameter.

[C-Kwik]

From what I know the t04b cannot flow as much air so it can't support as much hp. It's supposed to be alot smaller than the t04e.

Overall, yes the T04B will flow less, but that's not the big advantage. Nor is it a disadvantage. It really depends on the application. There are of course some applications where a specific turbo may not work properly, but for the most part, choosing a turbo isn't just about flowing more. As long as the turbo will support the flow, what you really want to try and match is the efficiency. Most 240's will never see the max flow rate of any T04 compressor wheel.

[matt0941]

I wish I could say that I know more about the subject but fact is I do not. Either way I hate to harass people on the forums for information that can be found elsewhere. But this is one of the areas that I struggle with obtaining information as there is a limited amount available.

Specifically: what I am confused about is the definition of A/R ratio, and Trim. I read and re-read Corky Bell's explenation of both in Maximum Boost but am still unclear.

He explained it (to my understanding) as the area of the outlet of the compressor housing to a certain distance (radius) in the coil away from the center section. I am probably very wrong about this but still need some clarification. But he also described that the size of the area of the compressor outlet (I think) determines how fast the compressor spins and (maybe) determines flow rate. Again I am probably talking out of my a** right now as I cannot site the book as I left it at school. But what I am asking is: how does the A/R ratio determine ... well what DOES it determine.

I am about to shoot myself as I thought I knew something on the subject but as I try and explain it, just shows how little I know. Save me Turbo Guru's!

Matt

[hannibal]

A/R is a property of the turbine housing. A larger A/R will have more lag but flow better at higher rpm's. A smaller A/R will have less lag but on the top end, it wont be able to efficiently handle as much air flow. At a given flow rate, the larger A/R will have higher air speed and therefore higher turbine speed.

Im not too sure about trim. I believe it refers to the shape of the turbine wheel.

Jay...not a guru

[S14Zilvia]

I am also unclear about "trims".

I've been pretty set on the t04e 50 trim from turbonetics, but I am not really sure what the trim means. I just know that the compressor map fits well.

[d240t2]

Trim is the ratio of major and minor diameters. Look at a compressor or turbine wheel...it is larger at the bottom...and smaller at the top. Trim refers to the ratio of the two sizes, basically.

Dennis

[matt0941]

So trim only refers to the Compressor wheels while A/R ratios apply to both Compressor Housing and Turbine Housing? (I am pretty sure thats wrong but I want to hear the correction)

-C'mon WD!

[S14Zilvia]

So trim only refers to the Compressor wheels while A/R ratios apply to both Compressor Housing and Turbine Housing? (I am pretty sure thats wrong but I want to hear the correction)

-C'mon WD!

I don't think so. The way I understand it trim refers to the ratio of the distance across the top of the wheel (turbine or compressor) to the distance across the bottom... or the diameter, not sure how it is actually measured but it's the same proportion, whereas a/r is area/radius and has to do with the size of the "tubes" that wrap around the wheels in relation to the distance to the center of the turbo.

[matt0941]

I think your A/R ratio is correct but just doesn't click in my head! I wish Corky Bell did a better job on explaining the basics.

[C-Kwik]

I wish I could say that I know more about the subject but fact is I do not. Either way I hate to harass people on the forums for information that can be found elsewhere. But this is one of the areas that I struggle with obtaining information as there is a limited amount available.

Specifically: what I am confused about is the definition of A/R ratio, and Trim. I read and re-read Corky Bell's explenation of both in Maximum Boost but am still unclear.

He explained it (to my understanding) as the area of the outlet of the compressor housing to a certain distance (radius) in the coil away from the center section. I am probably very wrong about this but still need some clarification. But he also described that the size of the area of the compressor outlet (I think) determines how fast the compressor spins and (maybe) determines flow rate. Again I am probably talking out of my a** right now as I cannot site the book as I left it at school. But what I am asking is: how does the A/R ratio determine ... well what DOES it determine.

I am about to shoot myself as I thought I knew something on the subject but as I try and explain it, just shows how little I know. Save me Turbo Guru's!

Matt

Ultimately, like using different size turbo parts using different A/R ratios change the balance between response and airflow. Particularly in the turbine section. While Radius usually remains the same, Area can be reduced to increase air velocity through the nozzle at lower airflow or increased to allow for more flow through the turbo. The A/R seems to have a smaller overall effect, but can still make a difference in the way a turbo feels. Larger Compressor A/R's tend to cause more of a sudden spool-up characteristic, while smaller A/R's tend to spool over a longer period of time. But Compressor A/R's aren't really discussed in Corky's Book.

[C-Kwik]

So trim only refers to the Compressor wheels while A/R ratios apply to both Compressor Housing and Turbine Housing? (I am pretty sure thats wrong but I want to hear the correction)

-C'mon WD!

Trim is referred to for both Compressor and Turbine wheels. I believe the calculation to get the trim is a bit more tricky. I haven't had time to try and figure it out. I belive Mike Kojima pointed something out about this in his Suck, Squish, Bang, Blow Tech articles in SCC Magazine. I can't remember for sure, but he elaborates quite a bit on the same things that Corky hits. It's great reading if you can get your hands on it since it provides another explanation that might help you make more sense of it. I lent mine to a friend, so I can't tell you which issues they are in.

[matt0941]

Compressor A/R's tend to cause more of a sudden spool-up characteristic, while smaller A/R's tend to spool over a longer period of time.

Thanks alot for your time C-Kwik (now and in the past). But two questions arise.

1) When discussing A/R ratios are people usually reffering to turbine or compressor?

2)You say that (I may be taking your words to litterally but just for the sake of the argument): Larger compressor A/R ratio causes quicker spool up, and smaller A/R ratio causes longer time before spool up... So keeping radius a constant;

-Larger nozzle Area = Quicker Spool-Smaller nozzle Area = Slower Spool

But wouldn't it make sense that these were vise versa due to the fact that air velocity coming out of the nozzle would be moving faster through a smaller area, causing quicker spool. And moving slower through a larger area, causing slower spool.

Could you please prove me wrong in this area? I am interested to know.

Thanks again to all info-providers.

-Matt

[ITR_KILLR]

ok, a 50trim is perfectly matched to the stage III wheel, and 60 trim matches up good with the stage V wheel.

the A/R of the turbine side is important b/c it determines spool-up characteristics. the .63 A/R spools up faster than the .82

good street turbo for 300+ whp50 trim stage III T3/t04E .63 A/R exh sidespools up pretty quick

400+whp50 trim stage III T3/T04E .82 A/R exh sidepretty laggy, buts makes more power

500whp

60 trim stage V T3/T04E .82 A/Rnot very practical on the street, but its been done;)

hope this helps

[syka24et]

Seem likme everytime I think I have a good understanding and know what turbo I want I read some more and am back to square one.

? The t04e 60trim with a stage 3 wheel and a 82A/R would be insufficent in terms of flow for our applications?I was going that route, Is a stage five turbine wheel needed for that?

[encasemyheart]

ok, a 50trim is perfectly matched to the stage III wheel, and 60 trim matches up good with the stage V wheel.

the A/R of the turbine side is important b/c it determines spool-up characteristics. the .63 A/R spools up faster than the .82

good street turbo for 300+ whp50 trim stage III T3/t04E .63 A/R exh sidespools up pretty quick

400+whp50 trim stage III T3/T04E .82 A/R exh sidepretty laggy, buts makes more power

500whp

60 trim stage V T3/T04E .82 A/Rnot very practical on the street, but its been done;)

hope this helps

So you're saying up to 400 use a t04e 50 trim .63A/R?

And what's the lag difference between the same trim, different A/R? A few hundred rpm? 500rpm?

[ITR_KILLR]

I'm saying if you want a low to mid 300whp car (easily), with good spoolup (for a non ball bearing turbo) the 50 trim .63 would do fine. if you want 400-450whp, and can wait another ~800rpm for spoolup, go for the 50 trim .82

[hannibal]

Matt,[quote=" matt0941 1) When discussing A/R ratios are people usually reffering to turbine or compressor?[/quote]People generally use A/R to refer to the turbine side. I think the turbine's A/R has a much bigger affect on spool up time and lag than the compressor's A/R.

Quote »2)You say that (I may be taking your words to litterally but just for the sake of the argument): Larger compressor A/R ratio causes quicker spool up, and smaller A/R ratio causes longer time before spool up[/quote]I never considered this before, but the compressor side is almost the reverse of the turbo side. Think about it.On the turbine side, the exhaust gas travels thru the housing before meeting the turbine wheel. So when you want faster spool up (and less lag), a smaller A/R gets the gas thru the housing and to the wheel faster.On the compressor side, it's the opposite. The intake air first hits the wheel, then travels thru the housing and on to the intake. So to get the air thru as efficiently as possible, a compressor housing with a larger A/R will flow better than a smaller A/R.You're more concerned with air speed on the turbine side than on the intake side cause you can't make boost until that turbine wheel starts spinning. On the compressor side, you just need to get the air that's being compressed from the wheel to the intake as easily as possible.

It's just a theory... I might be overlooking something pretty important here.C-Kwik, what do you think?? Am I on to something, or am I talking talking out my asss?

[C-Kwik]

Thanks alot for your time C-Kwik (now and in the past). But two questions arise.

1) When discussing A/R ratios are people usually reffering to turbine or compressor?

2)You say that (I may be taking your words to litterally but just for the sake of the argument): Larger compressor A/R ratio causes quicker spool up, and smaller A/R ratio causes longer time before spool up... So keeping radius a constant;

-Larger nozzle Area = Quicker Spool-Smaller nozzle Area = Slower Spool

But wouldn't it make sense that these were vise versa due to the fact that air velocity coming out of the nozzle would be moving faster through a smaller area, causing quicker spool. And moving slower through a larger area, causing slower spool.

Could you please prove me wrong in this area? I am interested to know.

Thanks again to all info-providers.

-Matt

1) Could be either. Most turbo people will tend to be more specific as to which A/R they are referring to.

2)I think IWannaS15 might be right. I haven't seen much literature on compressor A/R effects, but my logic leads me to the same theory. I was referring to the compressor A/R earlier. What you are saying is correct for turbine A/R's.

[C-Kwik]

ok, a 50trim is perfectly matched to the stage III wheel, and 60 trim matches up good with the stage V wheel

What makes it a perfect match? There is really no such thing as one perfect match. You use different turbo specs to achieve some varying results. It all depends on what you want out of the system and what application it will be used for.

[matt0941]

Very good and informative post so far guys. Tomorrow I will post something from MAXIMUM BOOST that kind confused me that I think will be very valid.

But I think one of my largest problems with visualizing this whole incident (not the proper word but eh) is the fact that I have never really seen the inside of a Turbine. Are the blades that spin the bearing (and eventually the blades of the compressor section) actually inside the housing of the turbine or directly after?

[ITR_KILLR]

mainly the turbine A/R determines spool-up time, not the comp. A/R.

the stage III wheel is better suited to the 50trim

the stage V wheel is better suited to the 60 trim.

not to say that other trims and wheels wont work, or work well, but these combos prove to be pretty efficient together for our applications.

I'm no turbo expert by far, just passing on knowledge that I've learned.

[hannibal]

[quote=" matt0941 Are the blades that spin the bearing (and eventually the blades of the compressor section) actually inside the housing of the turbine or directly after?[/quote]

The blades (and wheel) are inside the housing. The housing's job is to direct the exhaust gas to the wheel. The gas flows from the manifold, around the spiral section, and out the middle of the housing. The wheel is basically the last thing the exhaust gas hits as it exits the housing and heads out the exhaust system...

Jay

[matt0941]

Thanks alot for the attachment and the information.

[syka24et]

Matt your right ther is a lot of good info here. I was planning to go with a t60 with a 82 a/r and a stage 3wheel. I know the stage 5 flow better but would no the stage 3 add even more lag to the 82a/r, I was thinking the 82 a/r should flow good enough for 4oo plus hp. Am I wrong abvout this??

Ps C-kiwk thanks for the help a little while back 60-1 is a no-no:)