T3/TO4E, T25, T28 what does it all mean? Why do most people use T3s when KA-Ting?

[Daemos]

So total noob here when it comes to turbos. Been contimplating my choices for alot of things.

So my main question is what's with the T3s in all the turbos everyone seems to use?

I know the T3 means the type of housing, but isn't that a larger turbo which would take a long time to spool? (I think...remember me = noob)

How come people don't use T25/T28s on the KATs? I really like the Disco Potato Turbo, because it seems to spool quick on an SR20, and with the larger engine on the KA24 it would spool even faster

Or is there just not any T25/T28 housings available for the KA engine?

[Checkered-Member]

Well, for a 2.0L engine a T25 is barely enough. A T28 is a bit better (see S15)

For a 2.4L engine (like the KA) you need a bigger turbine housing (T3) because much more exhausts is available to spool the turbo, and because the engine flows so much, it needs an even bigger Compressor housing like the T4

Does this all make sense?

people use a T3 turbine because the T25-28 is to small, and a T4 is too big (in most cases at least)

[240marcuSX]

the general consensus is that the T25s and 28s are too small for the 2.4 liter. i dont think anyone has actually done it though.

Maximum Boost by Corky Bell is a good book that will help you understand some things, i got mine off amazon for like $30.

most KA-T guys use some sort of T3/T4 because the compressor is big enough to create decent power, and the turbine is small enough to spool quicker than just a straight T4.

what kind of power are you looking to make? what are you going to use the car for?

[Checkered-Member]

what kind of power are you looking to make? what are you going to use the car for?

He has a Sentra with a QR25DE, so he is just stopping by....

[andrave]

guys have done turbo ka's with T25/28.. dyno charts show max power at like 4k rpm and it drops off towards redline. pushing the poor little turbo way too hard, and probably heating the air up a lot and restricting the exhaust flow as well.

[240marcuSX]

really? ive never seen it.

[bbandit]

i thought aceinhole has t25 on his ka-t?

[GlacierFreeze]

i thought aceinhole has t25 on his ka-t?

Yes and his powerband was quite nice if I must say so myself. He had 225ft/lbs of tq at 2.5k rpms , it pulled nicely all the way to around the 6k area (iirc) and slowly dropped off. I think it is a good 250rwhp max turbo with instant power down low.

[andrave]

hmm someone posted a dyno of a T25 and it was peaky around the middle and then towards redline it started to flatline, then it went.. dropimportant to remember there are like 30 thousand different T25/T28 configurations too. If you were to use a single one of the turbos I have, for instance (T25, some consider it a T28, I don't know the diff) with a .42 turbine... you would be like wrapping your hands around the engine's neck and choking it.

[Daemos]

Ah more clarification.

I'm looking to build a project car. I was going to import one from japan with a CA18DET...which would be the same price as buying a used 240SX here..(in Canada) sell my Spec V and mod it.

But from a reliablity stand point, the 240SX will probally be alot easier to get parts for (I'm a student) and cheaper to maintain in the long run. Which is what I'm looking for.

The car will be used as a daily, street, winter, autox car Although in winter I plan to run 0 boost + diffrent fuel map, so I'm just making enough power to drive through snow without spinning.

So I was just comming here to dig around, learning as people call it

What I want is probally 350whp...I know what needs to be done, and I have my budget set out for it, custom rods, and pistons will be done, I plan to use a Power FC for tuning/ecu management, and new cams, maybe springs (if needed)and the rest has to come from a turbokit somewhere + an engine rebuild.

So I was just looking for options, I want fast spool that pulls strong to redline. Hoping for mid to high 12s drag, while still awsome at autox (if you read the CA forums, I posted something like this a while ago)

PS the Spec V uses the QR25DET...there IS a turbo kit available for it, makes nice power...however I'm getting sick of front wheel drive issues, and made in mexico quality

[C-Kwik]

So total noob here when it comes to turbos. Been contimplating my choices for alot of things.

So my main question is what's with the T3s in all the turbos everyone seems to use?

I know the T3 means the type of housing, but isn't that a larger turbo which would take a long time to spool? (I think...remember me = noob)

How come people don't use T25/T28s on the KATs? I really like the Disco Potato Turbo, because it seems to spool quick on an SR20, and with the larger engine on the KA24 it would spool even faster

Or is there just not any T25/T28 housings available for the KA engine?

T3's are relatively cheap. Many go with T3's they can find in a junkyard. The Z31 VG30ET had a T3. There are many other OEM T3's out there.

Larger turbo do typically have a later boost threshold and slower response. But larger turbos tend to have better efficiency and use turbine energy a lot better. This translates to more power for a given amount of boost.

Too small a turbo can tend to choke a motor at higher RPM's and boost. T3's start to show signs of this on a KA.

As far as hitting 350 HP on a T3...forget it. T3's can berely support the airflow required for that kind of power and as you approach that kind fo airflow, you will be getting a very inefficient compression, inefficient turbine operation and a lot of backpressure as turbine shaft torque and RPM need to be very high. The T3/T04E hybrid can handle it much better. A straight T4 would be even better efficiencywise, but spool a bit slower than the hybrid.

[Daemos]

hmmm...that's really wierd.

How is a T3 too small? But with an SR20 a T28 can make 350 whp? Isn't the T3 larger than a T28...I would expect it to beable to make atleast that.

T3/T04E hybrid though that might be something I might want to look at, but when does boost kick in? I want something that spools fast and makes ample power.

Like with an SR/CA I could probally go with a Disco Potato T25/T28 Hybrid or a HKS GT2535 and make 350whp and have it spool by like 3000 rpm (but that's with a higher redline mind you)

But maybe I'll be looking into a T3/04 Hybrid. Does anyone sell a prefab kit that can handle 350whp as long as the engine is built to withstand that (I'm going to use my own enginemanagement, so I probally wouldn't use the one that comes with the kit)

Perhaps I should also be looking into a Recirculating BOV to keep airflow there...hmmm

[C-Kwik]

The max airflow of the largest T3 I have a map for is 36 lbs/minute. Typically, if you multiply the airflow you are running by 10, that will give you a rough estimate of the kind of power you can acheive. So in this case, 360 HP. However, 36 lbs of air on a T3 is getting in a low efficiency range where the charge is both hot and the turbine is fighting internal aerodynamic drag. Not to mention the turbine is spinning at 153,000 RPM. Most T4 compressors would be closer to 100,000 RPM at this point. So using the times 10 caluculation of airflow gets very innaccurate here.

Even the Disco Potato will see signs of this. The Disco Potato in fact has a max flow of 37-38 lbs/minute and would also be seeing about 65% efficiency at a very high 165,000 RPM. The Disco Potato is not known for it's peak HP ability. It is known for its very quick response and high efficiency for such a small turbo. The Disco Potato is about as big as a stock SR turbo and almost a perfect bolt-on. It spools faster than a SR turbo, has better efficiency and puts ouot more HP per psi of boost. Most cars running this turbo run somewhere around 280 HP.

And I've never heard of a T28 on an SR making 350 HP.

[Daemos]

hmmm...

That makes sence to me. Time to do more research on my part. For some reason I was really against the KA. but when I thought about it, economically it would be the best choice for me, since I can go to a local nissan dealership and get almost all the parts I need

[andrave]

even with a CA18det, making 350hp is going to take more than a T28. A 350hp CA is a pretty high HP beast for a 1.8 liter. I would say with the same amount of work the ka would probably be more reliable and a better daily driver because of its greater displacement and less need for boost. As for your plan I don't see how you are going to run 0 boost.. sounds tricky.

[Daemos]

even with a CA18det, making 350hp is going to take more than a T28. A 350hp CA is a pretty high HP beast for a 1.8 liter. I would say with the same amount of work the ka would probably be more reliable and a better daily driver because of its greater displacement and less need for boost. As for your plan I don't see how you are going to run 0 boost.. sounds tricky.

how to run 0 boost? Pretty simple. Just keep the Turbo in a vaccum

It works perfect on my Buddy's WRX and his Cobb tuning ECU device. He sets it to valet mode, car has rev limit at 4000 rpm, and stays in a vaccum

It might be harder than I'm thinking (everything is :p) but torque + snow = spin

[TogueDrifter]

When you guys refer to the T3 turbo what brand of turbo, or are they all the same (turbonetics, garrret, etc...)?

[TXCumtrensh]

how to run 0 boost? Pretty simple. Just keep the Turbo in a vaccum

It works perfect on my Buddy's WRX and his Cobb tuning ECU device. He sets it to valet mode, car has rev limit at 4000 rpm, and stays in a vaccum

It might be harder than I'm thinking (everything is :p) but torque + snow = spin

seems to me like it would just keep the wastegate open.. that would = no boost... i never knew WRX's had a valet mode... the one that came to my shop the other day didnt have it on.. .. i had to warm up its new tires

[1991S13]

He had a valet mode because of the Cobb Tuning ECU, I don't think you can get a stock car with a valet mode. My cousin's Impreza has a valet key though, lol.

Togue Drifter - T3 etc. is referring to the size, not the brand so yes you could get a T3 from Turbonetics, Garrett, etc.

[TogueDrifter]

oh ok, Thanks!