Question about T25 vs. T28 turbo

[BoostedTRD]

I know since T25 turbo is smaller it spools up a lot quicker probably around 1500-2500 rpm if I am not wrong. Do you guys know at what rpm the T28 kicks in, I am guessing probably around 3000-3500 I could be wrong but just want to know.

I am still debating if I should go with the T28 or T25. The T28 will probably need a rebuild since its not spinning freely it could so be since its sitting around for a while now. It could just be gunk, I will be taking it to my mechanic this weekend to see what he says. I have rebuild a t3/t4 turbocharger so its not a big deal to rebuild it, it just takes a bit since I have to send the turbine wheels and shaft to get balanced.

Since our cars redline at 6250 rpm vs my old Honda 8500-9200rpm I am not sure if it is better to go with t25 so boost kicks in quicker and I can use it all the way to redline or use t28 and only use it for 3200 rpms. What do you guys think?

[CTScott]

I've been doing some work as of late on a Lotus Elise (2ZZ-GE Toyota engine) with a T28 turbo. The T28 starts to spool in the mid 3K range and I don't see transition from Vacuum to boost until nearly 4000 RPM. After having had a blitz supercharger on my Yaris, I think an application like this (with such a high spooling turbo) really needs to be dual charged. I have another client who will be bringing me a Supercharged Elise in the next couple of weeks and I look forward to seeing how that performs versus the T28 turboed one.

[BoostedTRD]

Originally Posted by CTScott

I've been doing some work as of late on a Lotus Elise (2ZZ-GE Toyota engine) with a T28 turbo. The T28 starts to spool in the mid 3K range and I don't see transition from Vacuum to boost until nearly 4000 RPM. After having had a blitz supercharger on my Yaris, I think an application like this (with such a high spooling turbo) really needs to be dual charged. I have another client who will be bringing me a Supercharged Elise in the next couple of weeks and I look forward to seeing how that performs versus the T28 turboed one.

damn now that makes me really think about getting a T25. I guess the only benefit asides from the power with T28 will be being able to drive to the dyno after installation without going into boost lol.

[kou]

I would say a T25 is a good size for 1.5l engine that way you are not revving to high to make power. I think my next turbo will be a GT2554r,GT2854r or the smallest garret T3.

[BoostedTRD]

Originally Posted by kou

I would say a T25 is a good size for 1.5l engine that way you are not revving to high to make power. I think my next turbo will be a GT2554r,GT2854r or the smallest garret T3.

Kou, with your T25 at what rpm does boost kick in?

[BoostedTRD]

Also with my T28 I have a custom 3inch downpipe that would fit a T25 without any problem. How would a 3 inch downpipe work with a T25 if I decide to go with a T25? will it be overkill?

[kou]

The turbo I have would be at 10psi at 3000rpm I am using 2.25'' exhaust all the way from the turbo I have a high flow cat a resonator and a muffler. You should be okay with a large down pipe but I would step down the size a foot off the turbo. Some people think bigger is better but from what I have found with the yaris if you want some torque down low you have to have a little smaller exhaust and it has to go to the bumper for example I tried to have the exhaust come out before the rear tire but I lost all around town power and that was with the turbo installed sure it would be great up top but for me not what I want. You have to think different than a honda where power is made from 4500-8k

[BoostedTRD]

Originally Posted by kou

The turbo I have would be at 10psi at 3000rpm I am using 2.25'' exhaust all the way from the turbo I have a high flow cat a resonator and a muffler. You should be okay with a large down pipe but I would step down the size a foot off the turbo. Some people think bigger is better but from what I have found with the yaris if you want some torque down low you have to have a little smaller exhaust and it has to go to the bumper for example I tried to have the exhaust come out before the rear tire but I lost all around town power and that was with the turbo installed sure it would be great up top but for me not what I want. You have to think different than a honda where power is made from 4500-8k

Thanks for this that's exactly what I thought. Has anybody else used a 3 inch down pipe on their setup?

[kou]

You are welcome. You really have to decide on a hp number you want and what you want to use the car for daily drive,dragracing,trackday etc?. I would be more the happy with a very reliable dd 250hp Yaris. Because I live in NJ and I drive the car everyday in every weather condition traction can become an issue, wheel spin at highway speeds in the rain is something you have to deal with snow is not so much of a problem because I have dedicated winter wheels and tires and it can actually be fun. I am installing an TRD LSD soon and I hope this will help so I don't get pulled to one side by wheelspin in the rain.
I am a fan of WRC and BTCC racing so I guess I am trying to build my car with a blend of both.

[BoostedTRD]

Originally Posted by kou

You are welcome. You really have to decide on a hp number you want and what you want to use the car for daily drive,dragracing,trackday etc?. I would be more the happy with a very reliable dd 250hp Yaris. Because I live in NJ and I drive the car everyday in every weather condition traction can become an issue, wheel spin at highway speeds in the rain is something you have to deal with snow is not so much of a problem because I have dedicated winter wheels and tires and it can actually be fun. I am installing an TRD LSD soon and I hope this will help so I don't get pulled to one side by wheelspin in the rain.
I am a fan of WRC and BTCC racing so I guess I am trying to build my car with a blend of both.

dude that's exactly what I want 250-300whp. I want to use it for daily driving and just to enjoy it. I had a 92 civic hatchback with B18c5 with inline pro turbo kit. 327whp with 267 torque, I only had it for 6 months before it got stolen so I didn't really enjoyed much. That's why I want to turbo my Yaris and keep it stock looking from the outside so it does not attract any attention until they hear my BOV go off lol.

[Ryze268]

I was worried when I saw how small my T25 turbo was (.48/.49) I heard that it's gonna run out of puff in the higher RPMs. Sadly, that's not what I want. 1st and 2nd gears in my Vitz are decent as the car doesn't weigh much, 3Rd n upwards are very uneventful but I'll see how much this tiny turbo improves the car's acceleration.

[BoostedTRD]

Originally Posted by Ryze268

I was worried when I saw how small my T25 turbo was (.48/.49) I heard that it's gonna run out of puff in the higher RPMs. Sadly, that's not what I want. 1st and 2nd gears in my Vitz are decent as the car doesn't weigh much, 3Rd n upwards are very uneventful but I'll see how much this tiny turbo improves the car's acceleration.

I want a turbo that will spool from low rpm but not loose juice on higher RPM's. The T25 is good from low rpm but I am not sure how good it is at higher RPM's on the other hand the T28 is does not start spooling until 3500-4000 but it has plenty of juice on high rpms

[kou]

We have a low redline and good torque stock you want to try and emulate that with your turbo setup. This engine was not designed for high revs as much as it was for low down torque for a 1.5l its build is robust the cylinder walls are as thick as the 2.4l in the TC and they hold boost well.
When searching for turbos its hard to find info for our application because nearly every other car revs 2-3k more and are moving more air and need something that breathes a lot up top.
I very rarely go to redline as now I am not searching for power(also have stock motor and clutch 130K miles which will change soon) because between 2500-3000rpm the power is in any gear.

[Ryze268]

Originally Posted by kou

We have a low redline and good torque stock you want to try and emulate that with your turbo setup. This engine was not designed for high revs as much as it was for low down torque for a 1.5l its build is robust the cylinder walls are as thick as the 2.4l in the TC and they hold boost well.
When searching for turbos its hard to find info for our application because nearly every other car revs 2-3k more and are moving more air and need something that breathes a lot up top.
I very rarely go to redline as now I am not searching for power(also have stock motor and clutch 130K miles which will change soon) because between 2500-3000rpm the power is in any gear.

This is very true, I wish our rev limit was a bit higher

[malibuguy]

In my tercel my turbo start building boost at 1300rpm...my torque curve is awesome.

Im putting a gt2554r on my Yaris very soon...was going to go smaller but i wanted the spool and durability of ball bearings...plus i got the turbo for a very good price!

[Blown_xa]

If your goal is 250 to 300whp, I would steer away from a small turbo. I have been through many turbo sizes.... The 250 to 300whp range becomes a fight on "usable" power. Throw some valve springs in the head if the bottom end is built, and run a turbo rated for around 400hp. Im currently running a t3/4 50 trim with rev limiter set to 8000rpm and my car is easy to drive fast without blowing the tires away. I used to run smaller turbos at the same power level, and it was nothing but a pedal dance to keep traction unless I was at the strip rocking drag slicks. Stock head with valvesprings, 8k rpm with a turbo rated for 350 to 425hp... That's the ticket

[why?]

Originally Posted by Blown_xa

If your goal is 250 to 300whp, I would steer away from a small turbo. I have been through many turbo sizes.... The 250 to 300whp range becomes a fight on "usable" power. Throw some valve springs in the head if the bottom end is built, and run a turbo rated for around 400hp. Im currently running a t3/4 50 trim with rev limiter set to 8000rpm and my car is easy to drive fast without blowing the tires away. I used to run smaller turbos at the same power level, and it was nothing but a pedal dance to keep traction unless I was at the strip rocking drag slicks. Stock head with valvesprings, 8k rpm with a turbo rated for 350 to 425hp... That's the ticket

how long do you think the engine will last revving to 8k?

[CTScott]

As an update/correction to what I said about the T28 not spooling well on the 2ZZ-GE Lotus - I found that wastegate was improperly configured on the Adaptronic stand-alone ECU.

When the owner first installed the turbo kit (which included a catless high flow exhaust) he was having significant issues with overboosting, so he set the wastegate to start opening at 2000 RPM. He later bored the wastegate opening to correct the overboost, but never corrected the wastegate settings.

Once I noticed that and corrected it, the T28 transitions from vacuum to boost at about 2500 RPM and hits full boost (current set at 12 psi) at 4000 RPM and maintains it right up to the Lotus's 8500 RPM redline with the lift cam fully actuated.