.48 A/R turbine, .60 A/R compressor-Running out of juice at 5k--suggestions?

[MarkEmark]

Just as the title says:I have a T3 Super 60 B, .48 a/r turbine, .60 compressor. I realized when I was buying it that it was a bit small for the KA, but I really wanted to keep the incredible throttle-response/minimal turbo lag/explosive low-end of a smaller turbo, and keep boosting up top. It works very well from 3k-5k rpm, but past 5k, it drops from 9 psi to 6.5 psi/6 psi.

My question: What is limiting it from boosting at high rpms, the low turbine a/r, or the low compressor a/r? I'm fairly positive it is the low turbine a/r. Instead of getting an entirely new turbo, which i don't want to do because mine is brand new, could I get just a bigger turbine housing from another T3 and use the same turbine wheel to increase the A/R, to say, .54 or higher? Would this ensure full boost past 5k rpm? I do NOT want to sacrifice low-end/daily drivability/excellent throtte response/little turbo lag. I just want to make it boost a little bit better up top.

How available would these T3 turbine housings be? And how can I ensure that it will work with my turbine wheel? And most importantly, how would I be able to determine what the NEW a/r for the turbine would be (without physical measuring)?

Thanks for the input.MARC

[TrunkMonkey]

isn't this you?

upgrade your turbo, or switch back to stock cams. why ask the same question again ?

-demetrius

[MarkEmark]

The previous question was only about cams. i got my answer-they aren't killing my powerband.

This was a very simple question-I am not going to throw away a brand new turbo just for a little power from 5-6k rpm.

I want to know if I can just upgrade the turbine housing to a bigger one to increase the a/r. I'm not even sure what is killing the top end, the compressor or the turbine? I tend to think it's the turbine. And if I can just upgrade the housing, this can be done cheaply...I just want to know what ones are "compatible" with it.

--sorry If I keep annoying you, demetrius

[TrunkMonkey]

The previous question was only about cams. i got my answer-they aren't killing my powerband.

This was a very simple question-I am not going to throw away a brand new turbo just for a little power from 5-6k rpm.

sell it.

I want to know if I can just upgrade the turbine housing to a bigger one to increase the a/r. I'm not even sure what is killing the top end, the compressor or the turbine? I tend to think it's the turbine. And if I can just upgrade the housing, this can be done cheaply...I just want to know what ones are "compatible" with it.

once you upgrade, your turbine will be bigger than your compressor.

stolen from C-Kwik's post in the .96 a/r turbine thread...

As far as the question about running a large turbine with a small compressor. Larger compressors move more air at a lower shaft speed. So a smaller compressor would need to spin faster. To spin a compressor faster, you need to have the turbine spin faster. A smaller compressor would only give a very small advantage over a larger one due to it's lighter weight, but since it's also moving less air for a given shaft speed, that would likely negate the benefits there or perhaps even make it worse.

- C-Kwik

in short, you'll be back to square one. your turbo is just too small.

--sorry If I keep annoying you, demetrius

i'm never annoyed, but i'm sorry if it seems like i am.

-demetrius

[WDRacing]

The exhaust isn't escaping the turbine section fast enough causing a serious back pressure in the upper rpm band. The best way to fix this is with a largwr AR section. Like a .63 or better. The .63 will still spool very well while giving more top end room.

WD

[MarkEmark]

in short, you'll be back to square one. your turbo is just too small.

--sorry If I keep annoying you, demetrius

i'm never annoyed, but i'm sorry if it seems like i am.

-demetrius

[/QUOTE]

Did you think I was referring to upgrading the turbine WHEEL? I'm just referring to upgrading the turbine HOUSING, by making the housing BIGGER. I'm asking if I can upgrade the housing to a bigger one, say .56 a/r...which is still a lower number than the compressor, but will be better than a .48 a/r for the turbine. So I ask again...can I just upgrade the EXHAUST housing to a larger one to yield a higher a/r, and if so, which ones are compatible?

[MarkEmark]

This is what I'm talking about...

http://cgi.ebay.com/ebaymotors...07807

looks like it'd fit mine quite nicely. It's worth a shot anyway--I can always sell my existing housing, which is in perfect shape, or sell the .63 one if i don't like it. Or, keep one for "daily driving" and one for "spirited" lol...even though it takes a while to swap them out.

Will this work for mine?!? I don't know what kind of wheel I have...just that it's the T3 Super 60B, the same thing as the T3 Super 60 except there's no bolt-flange for the inlet, just a cylinder to accept silicone coupling.

[j-z]

are you sure youre not just having boost creep issues? thats what it sounds like to me. are you running an internal gate? you run 9 psi from 3-5k then past that it sounds like the normal boost level. do you have a mbc?

[MarkEmark]

It's very consistent in the boost delivery, even if there is a fluctuation between the boost at low rpms and at high rpms.

I'm not familiar with "boost creep" issues...please elaborate.

Yes, I'm running an internal wastegate, 9 psi, and I have a mbc.

I think the main problem is that the turbine a/r is just too small for a 2.4 liter past 5k rpm--the engine is expelling a lot of air past 5k rpm, and the turbo is just too small. Anyway, I found a T3 turbine housing, .63 a/r, brand new for $100 that i might try out...

Loosing boost past 5k is not necessarily a bad thing--when the engine is under the most stress, at say, redline, it's not under the maximum boost. The boost almost always drops toward redline in almost any engine...especially if the turbo is past its efficiency.

[j-z]

dude save your money. trash you mbc that you probably made. save up and get a profec b to regulate your boost to 9 psi. that will rid of your problems. its not your exhaust housing thats making your car slow. its your pos mbc. its dropping off on the top. trust me, once you have it regulated to 9 psi throughout the entire rpm band youll be happy. if you get the .63 housing its gonna do the same thing but with even more lag.

[MarkEmark]

I'd be willing to bet you it has very little to do with the mbc and a helluva lot to do with the small turbine. Explain to me how the mbc would cause it to drop boost past 5k rpm. The last turbo I had (.48 a/r turbine, .42 compressor) did the same thing as my current turbo, except at a lower rpm...ie, the boost dropped past 4k rpm. What fixed it? A higher a/r compressor. The small a/r of my turbine is what's limiting me right now. There's no sense in buying fancy digital boost controllers when an MBC does the exact same thing. BTW, i'd get a JWT ECU (and probably will be in the near future) before I'd mess around with profec.

Do you have any experience with KA-t's?

[j-z]

does it ****ing matter if i have experience with kats? you asked for suggestions and im giving them to you. and no i dont have experience with kats but i do have experience with turbos and mainting boost which is your problem. the motor has nothing to do with your problem man. i bet when you had your smaller turbo on when it did the same thing you had the mbc on. im willing to bet you that it is your pos mbc. is it one of those diy mbcs or one like a turbo xs? take it off and see if it maintains the same boost level throughout the enitre rpm band. and what are you trying to say about getting a jwt ecu before you get a profec? btw there isnt really anything fancy about a profec.

[Z1500]

You are running out of compressor wheel. You should see the power we've goten out of the .48 housing. WAY more than you are running. A larger turbine housing isn't going to solve the problem.

Kevin

[j-z]

exactly what im trying to tell him. its not the ****ing turbine. i ran a .48 a/r on my bored 2.3 prelude motor. i dont think its the compressor either cause his boost pressure falls off. so the problem is whats regulating his pressure. you can have a small *** compressor wheel or whatever youre trying to say but still maintain the same boost level. thats why his car feels slow up top. of course cause your running 3-2.5 psi less up top. sometimes the amswer is alot more simple than it seems.

[MarkEmark]

That's strange...the moderators (demcj, WDRacing) both say that it's the size of my turbo that's killing me up top...

http://www.nissaninfiniticlub....43662

J-Z...I hope not all honda boys are as vulgar as you are. Take it easy with the cussing. No need for raging tempers.

I'm saying that I'd get a JWT over a profec because JWT is tried and true; I'd rather not screw around with so many variables witha profec; especially if I don't have consistent access to a dyno.

Kevin--What kind of compressor wheels are people running when they have .48 a/r turbines? I thought a .60 a/r for the compressor was plenty high.

I'll try and mess around with the MBC; if that doesn't work, I'll swap out the turbine housing--I've got plenty of time to do it (my car goes nowhere when there's snow on the ground), and it's only $100.

I'll keep you guys updated

[TrunkMonkey]

i wasn't aware that you were using a mbc, but if that was the problem you should be seeing boost spikes and fluctuations throughout the powerband. not just up top. it doesn't take much to check it though, just disconnect it and run at whatever psi the wastegate is set at.

-demetrius

[Z1500]

You are running off the map of that compressor wheel. It is called choke. That compressor will flow more air just not at that low boost. So turning up the boost will actually let it run full power into higher RPM.We are using .48 turbine housings on 48-54lb/min compressors and getting well over 400whp with them. For comparison sake your 60trim is a 36lb/min wheel.Do also take into consideration that it could be something else in the car holding you back. Cams, intercooler, etc.

Kevinhttp://www.agpturbo.com

[j-z]

whats holding him back is whats regulating his boost. just because im not a moderator or i dont have 1000+ posts doesnt mean i dont know anything. and how can you classify me as a "honda boy"? thats doesnt make any sense at all man. this has nothing to do with your problem that im trying to help you with. but your being too god damn stubborn to listen to my suggestion. incase you wernt aware, a greddy profec is an electronic boost controller. thats all it functions as, nothing else. it is the simplest electronic boost controller to use on the market, the profec B (my opinion). so not unless the jwt ecu youre talking about can regulate boost in any way then they have nothing to do with each other. see if you can borrow someones profec b. i gaurantee you that once you have boost regulated to a STRONG 9 psi throughout the entire rpm band you will stop complaining.

[MarkEmark]

Just like Demetrius said, I'm having no boost spikes anywhere, the boost is delivered consistently, and always the same way at the same place. THe only fluctuation is the gradual waning past 5k rpm.

z1500--How much more psi would you think I'd need to run to make it deliver consistent boost all the way up in the top end? I don't want to exceed 10, so I guess it's out of my control anyway.So with your 48-54 lb/min compressors, what is your A/R? Would increasing the size of the compressor housing work or am I just ignoring the real problem, which is that the compressor wheel is too small? So you don't think a .63 a/r turbine housing swap would offer any performance gain? I don't think anything's holding me back besides the turbo/boost delivery.

J-Z...I guess I classified you as a "honda boy" because the "car" part of your name that comes up when you post says "boosted prelude." Gee, I guess that makes sense that I'd call you a honda boy if you have/had a honda....I was merely pointing out that perhaps you're misrepresenting honda owners as cursing, nasty people who can't offer advice/help without "uncontrollable" profanity. But this is useless arguing; I'm not looking for a violent retort. Okay?

My bad about the profec--I assumed it was a piggy-back type unit like the AVC-R. How much do they go for? I don't see how an electic boost controller will give me a full 9 psi up to redline if a mbc wont...9 psi is 9 psi. You still haven't explained to me HOW my mbc is limiting me up top.

Anyway, once it's nice enough out, I'll take my car out with just the wastegate connected, see what it does. If boost still wanes past 5k rpm just like it does now, then obviously the mbc is not the problem.

I'll keep ya guys posted.

[Nathan]

You are running off the map of that compressor wheel. It is called choke. http://www.agpturbo.com

Or called surge...I don't think it's your turbine though as I know of .48 t3 turbines working fine on KA's.

[j-z]

the avcr is a boost controller also. its not a piggy back. the only reason why im telling you all of this is because of first hand experience. i had a pos mbc. it ****ing sucked. it would do the exact same thing youre describing. boost response was always the same and there were no spikes at all. just towards the higher rpms boost would fall off bad! so i took it off and said **** it. couple of weeks later i spent $200 for a used profec B and that solved my problem. and let me tell you that 10 psi throughout my whole entire rpm band was impressive. what youre saying just doesnt make sense. how it can be a turbine housing and all that. thats not causing you to loose boost. its whats regulating it for the fifth time. maybe you should stop assuming and be open minded.

[TrunkMonkey]

...I don't think it's your turbine though as I know of .48 t3 turbines working fine on KA's.

.48 turbines do work well on KAs, but how well with aftermarket cams? that's the question. pdm cams are probably the most aggressive cams on the market for the KA. depending on what stage you use, they lack on the bottom end and scream up top. they are NOT designed for boost.

btw MarkEmark, what stage cams are you using?

j-z, it may very well be the mbc. if you're right, then your right...BUT you need to drop the attitude.

-demetrius

[Nathan]

True, I dont know how a .48 would work with aftermarket cams. Mark, what kind of MBC do you have? J-Z, what kind of MBC did you have? I will most likely order a JoeP MBC this week.

[j-z]

youre right and i did. but how can he assume that i dont know anything? just because i only have been a member here for about a week. im trying to help the guy but hes assuming that since im new here i dont know jack. takes two to tango. anyways its gay arguing on a damn message board. just trying to help a fellow tuner out.

[MarkEmark]

.48 turbines do work well on KAs, but how well with aftermarket cams? that's the question. pdm cams are probably the most aggressive cams on the market for the KA. depending on what stage you use, they lack on the bottom end and scream up top. they are NOT designed for boost.

btw MarkEmark, what stage cams are you using?

j-z, it may very well be the mbc. if you're right, then your right...BUT you need to drop the attitude.

-demetrius

I'm using the PDM stage II cams (actually colt cams). These were supposed to be the VERY STREETABLE, NON-extreme cams designed for gain throughout the rev-range with little loss of torque. They have an incredibly stable idle, and when I was n/a, I noticed next to no loss in low-end torque. I contacted don before I turbocharged my car and he said the cams would be fine for around 7-10 psi. I trust him quite a bit. WDRacing said in my previous post (addressing my issue of camshafts) that my cams are actually a very suitable duration/overlap for the boost I'm running. If nissan didn't charge $11.50 PER SHIM (freakin' rip off), I'd sell my cams and just swap some stock cams in. But I'm not spending $175 + just for shims.

USED profec-b's are $200?!? That seems incredibly expensive, no? What else do they adjust besides boost? Is there a cheaper, and just-as-effective electronic boost controller?!? Again...if I disconnect my MBC and run it at what the wastegate's set at (i think it's like 6 psi), and it stays at 6 psi up to at least 6k rpm, then I know it's my mbc, which I will admit is a bit of creative plumbing and is home-made....

[j-z]

ok good. i gaurantee you thats what it is. avcr is a gear dependent boost controller. but thats all it does is control boost. its kinda confusing to work with. thats why i say the profec b is the easiest ebc to use. hence thats why i bought it. trust me the $200 i spent was well worth it. i took that ***** off to use on the 240 ha. brand new they are about $400. it has a high and low boost setting. you can also adjust the time of when you want the wastegate to open. i really liked that function. you can build boost ALOT faster by having it open right when you hit full boost. if you ask others they too will say to choose the profec b just because of its simplicity and how well it works.

[MarkEmark]

Hmm...I smell a christmas gift

I was browsing around ebay and saw a lot of profec-b's, some of them going for as low as $115 used. What is the difference between the old model and the new model profec b, besides the digital display on the new model? Is yours an older generation or newer generation one, J-Z?

Damn, all that I need is some of this freakin' snow to melt so I can get down and up my driveway to take 'er for a ride to diagnose the problem. BLOODY NEW ENGLAND WEATHER!!!!!!

[j-z]

i have the profec B. it has 3 dial knobs on it. dont get the A get the B model. make sure when you get a used one that it comes with the solenoid. as that is the most vital part.

[C-Kwik]

Changing the A/R is really only going to make a minor difference. If you really want to get a better top end consider the size of the turbo wheels as your limiting factor. The T3-S60 is a pretty good turbo, but as you approach redline, you start to approach a compressor efficiency as low as 65%. Efficiency is important in this case for two reasons. The obvious is the heat created. The not so obvious is the reason behind the lower efficiency. The reason it heats up more is because the turbo at that boost and airflow is not as aerodynamic. This means that it's harder for the compressor wheel to create that boost level. This means the turbine must absorb more energy to drive the compressor. This means the wastegate can't open as much which creates more backpressure.

If you are serious about making more power up top, consider at least changing the compressor. A much more efficient compressor, especially at the RPM and boost where you want more power can make a significant improvement.

[MarkEmark]

Well, I guess we were all (kinda) wrong. I disconnected my exhaust past the small downpipe today before we got some more of this wretched snow to see if my exhaust was the limiting factor and perhaps causing too much backpressure/choking the engine at high rpms. Turns out it was.

Before, it'd hit 10 psi and gradually wane to 6.5 psi past 5k rpm/Today, it hit 10 psi and stayed there till 6k rpm. By the time I was at 6k rpm in third, I was accelerating a bit too quickly for the road I was on, and I cant do this in second because the wheels spin.

It felt a LOT quicker today with just the downpipe + a 160 pound passenger + 40 more pounds of gas than it did a week ago, same weather, weighing 200 pounds less...too bad it's just too damn loud You can hear the turbo spooling from soo far away, it sounds like a jet engine

I guess my exhaust is so restrictive because of my downpipe(s). The first one is 2.5" and is a 90 degree elbow that goes right past the transmission, and he second one is another 90 degree elbow that goes to the rest of my exhaust, including my cat. The problem is, the place I got to make up the downpipe said they'd "mandrel bend" the pipes, and indeed they didnt. That, coupled with a catalytic converter (even though it IS a high flow-one) is robbing me of quite a bit of boost. The rest of my 2.5" exhaust is VERY straight and mandrel bent.

So, I want to not only fabricate a new downpipe from the turbo all the way to the catalytic converter that is ALL mandrel bent, but I want to have a test-pipe made replicating the cat in length/size with 2 flanges at the end. Then, I'll just leave the straight pipe in there all the time, and when I have to go through emissions, I'll pop the cat back in...

I was also thinking of perhaps making some y-type exhaust fitting right past the downpipe--each port having a standard flange, with one port blocked up and the rest of the exhaust gasses goingthrough the regular exhaust, etc, for when I know I'm going to be going in populated (cop-populated) areas/through emissions, and then the port blocked up that goes to the rest of the exhaust and the other one opened to the environment when I'm feeling "racey." I think it'd be fairly easily made. My question is, because it is a Y pipe (actually, think of an upside down Y), would the extra "stem" on the Y that is not being used, either for when the Y is opened up to the whole exhaust or just opened up past the downpipe cause a hindrance in flow/turbulent air?!? Anyway..looks like it's time for a new downpipe for me. The problem will be finding someone who can ACTUALLY mandrel bend pipes, ie, keep the piping the exact same diameter all the way around, as in the piping you can order from JC whitney. If this can't be done, then I'll be forced to order parts from JC whitney, cut them int he right angle, and have them welded together....

Damn...and I'm right in the middle of trying to find a JWT ecu/370 cc injectors. I'm gonna be busy this winter