Turbo Experts Help

[BreckenridgeCruiser]

I know there is a few ongoing battles about numbers from a lot of you, but it seems that you all know a ton more about turbos than I do.

My question is about a GT26 turbo off of a celica (3sgte IIRC). Now some have said that it is a bit big for a 3B, and that gave me pause, but i was just thinking that since I have a 2B if might change things.

A few things that may make this work:
The 2b has a 3.2L displacement instead of 3.4
It also has a higher compression ratio (21:1 as opposed to the 3b's 20:1)

So turbo experts, how would this affect the turboing of my engine?

I am still getting the A/R numbers from the owner. I know those are the make/break. for the sake of argument now, lets assume ti the stock configuration.

Thanks!

K

[Tapage]

CT26 .. the issue is Toyota ( as a factory part - turbo ) don't offer AR numbers or turbo maps for those CT-26 units .. so we figure that the trims are diferent ( making diferent turbo maps ) for diferent aplications ..

Since Toyota use the " same " CT26 from MR2 to Land Cruiser with the 1HD-T throught supras etc ..

Here few members have goos experiences with CT26 ..

[wesintl]

Your not going to get ar #'s off it. They measure the wheel in mm iirc. It should work ok.

[gerg]

In my experience with turbos it is not if it will work, but more of a question of when. My first turbo job was totally oversized, yet it still gave nice boost at highway speeds. It only lacked low end boost. I was very pleased overall with it for a first try. I too have a CT-26, but mine is from an MR2. I figure it is most likely very close to your turbo. After comparing the housing with other turbos it is my imediate observation that it is physically much larger than say Mainlanders turbo (he just mated a TD04). On the other hand Otterav has mated the infamous supra turbo with impressive numbers. I do believe he has really cranked up his fuel to do this. I am going to use my CT26 to experiment with the split housing. I am expecting it to be on the larger side, but I am doing a compound set up so I dont really care about that so much.
I would say it will work at higher rpm with tuning the EGTs to not exceed 1200F pre turbo.
It will progressively work its way down into the lower RPM range as you increase the fuel off your pump.
I would not recomend this cource to just anyone as you could get your EGTs up pretty quick. That being said... I plan on experimenting with this overfueling technique, but I dont think my wife will be driving my truck by herself alot.. heh
G

[BreckenridgeCruiser]

sorry that's what I meant: ct26 and GT25 have been two turos I have been comparing. It was just rebuilt so I might beb able t get some specs. I will post up if I find anything.

K

[Dougal]

The Garrett T25 is not the GT25.
The GT2052 is the closest thing in the current garrett range to the old T25.

There are at least three different CT26 turbos, www.mellett.com has all the info on which wheel sizes were fitted to which engine but A/R ratios and maps are not available.

Turbos work on airflow, so a slightly smaller engine has to turn slightly faster. With a compression ratio that high you don't want to add much boost, reducing the compression ratio (thicker head gasket, bigger head clearance volume etc) will reduce the stress on the engine internals when running boost.

[BreckenridgeCruiser]

Does that mean that less boost will have a larger effect on the output of the engine? That would essentially mean that a turbo that makes smaller boost for a lower compression engine (larger turbo Slower spool) will essentially be like a smaller turbo since my engine may not need as much boost to have the same effect?

K

[Dougal]

Originally Posted by BreckenridgeCruiser

Does that mean that less boost will have a larger effect on the output of the engine? That would essentially mean that a turbo that makes smaller boost for a lower compression engine (larger turbo Slower spool) will essentially be like a smaller turbo since my engine may not need as much boost to have the same effect?

K

Not quite.
Lowering the compression ratio will lower the off-boost efficiency a little, but it'll be eclipsed completely by the efficiency and power improvements that the turbo boost offers.

A larger turbo means you have a bigger proportion of your rev range with little or no boost. Boost can be limited to whatever level you want (up to what that engine/turbo/fuel combination is capable of) simply by making the wastegate rod adjustable.

[BreckenridgeCruiser]

Actually, let me rephrase:

In STOCK form (3.2 21:1 compression) the CT26 that people have said may be too big may be just right as my engine will produce the same exhaust output as the 3B (3.4 20:1). I am assuming that the above is true. I am not planning on messing with the compression ratios as I feel the 2B is a better engine for my needs. The lower displacement means slightly better economy, while the higher compression brings power back to the stock 3B level (from the TLC FAQ).

With that said the turbo is still a bit big and spool will be slower to reach max boost pressure that most people use (around 11psi I think). But if what you say is true and my engine will not be as ready to handle higher boost due to higher stock compression, wouldn't that also mean that a lower boost (expected at lower RPM) will affect the engine at lower boost due to the compression?

If THIS is true, then the turbo could be set for a lower max boost and therefore get to the new max boost sooner which would mean performance gains at lower RPM therefore earlier than expected compared to the baseline 3B.

For my assumptions to work you have to look at the exhausts effect on the turbo first, and then look at the turbo's effect on the engine second. From a layman's point of view, my engine may be a better candidate for this turbo as I might get a smoother spool and lower boost which will mean longer life of engine and turbo, especially since I am not trying to get a ton more power, just to compensate for altitude and get a little more power for highway driving.

K

[Dougal]

Originally Posted by BreckenridgeCruiser

Actually, let me rephrase:

In STOCK form (3.2 21:1 compression) the CT26 that people have said may be too big may be just right as my engine will produce the same exhaust output as the 3B (3.4 20:1). I am assuming that the above is true. I am not planning on messing with the compression ratios as I feel the 2B is a better engine for my needs. The lower displacement means slightly better economy, while the higher compression brings power back to the stock 3B level (from the TLC FAQ).

With that said the turbo is still a bit big and spool will be slower to reach max boost pressure that most people use (around 11psi I think). But if what you say is true and my engine will not be as ready to handle higher boost due to higher stock compression, wouldn't that also mean that a lower boost (expected at lower RPM) will affect the engine at lower boost due to the compression?

If THIS is true, then the turbo could be set for a lower max boost and therefore get to the new max boost sooner which would mean performance gains at lower RPM therefore earlier than expected compared to the baseline 3B.

For my assumptions to work you have to look at the exhausts effect on the turbo first, and then look at the turbo's effect on the engine second. From a layman's point of view, my engine may be a better candidate for this turbo as I might get a smoother spool and lower boost which will mean longer life of engine and turbo, especially since I am not trying to get a ton more power, just to compensate for altitude and get a little more power for highway driving.

K

The compression ratio does not change the volume of air an engine processes. Your engine has a smaller capacity so has to spin faster to spool a turbo than the 3B does.
The only way you can get a turbo to spool faster is by feeding it hotter exhaust gas.

The supra CT26 has the same size wheels as the CT26 fitted to the 4.2 litre 1HD-T. Does this tell you something?

Turbos are sized by matching the compressor to the engines airflow requirements, then selecting a suitable exhaust housing to get it to spool where you want it

[wesintl]

Originally Posted by Dougal

The supra CT26 has the same size wheels as the CT26 fitted to the 4.2 litre 1HD-T. Does this tell you something?

From his first post he's talking about a ct26 from a celica. Different ct26 than the supra.

[BreckenridgeCruiser]

Also, essentially, the heat of the air should not matter as mouch as volume and pressure of the air. In the case of a 2b with higher compression than a 3b, shouldn't it have higher pressure exhaust with a slightly lower volume (3.4 vs. 3.2)?

That is why I think it should bve the same as a 3b on the exhaust side.

So does a higher compression need a lower boost to see gains?

K

P.S. Wesintl: I'm going to try to get my rig down to the big gathering in august. Can't wait to pick your brain.

[Dougal]

Originally Posted by BreckenridgeCruiser

Also, essentially, the heat of the air should not matter as mouch as volume and pressure of the air. In the case of a 2b with higher compression than a 3b, shouldn't it have higher pressure exhaust with a slightly lower volume (3.4 vs. 3.2)?

That is why I think it should bve the same as a 3b on the exhaust side.

So does a higher compression need a lower boost to see gains?

K

P.S. Wesintl: I'm going to try to get my rig down to the big gathering in august. Can't wait to pick your brain.

Sorry I thought we were talking about the bigger CT26's.

The heat of the exhaust is of prime importance, hotter air provides a lot more energy to the exhaust turbine. It also results in a bigger volume and faster flow.
In short, higher temperature results in both higher pressure and more volume through the exhaust turbine.

The reason for less boost on a higher compression engine is to keep stress down on the head.

[wesintl]

Originally Posted by BreckenridgeCruiser

P.S. Wesintl: I'm going to try to get my rig down to the big gathering in august. Can't wait to pick your brain.

Not much to pick. I'm pretty much in the garrett camp. A .42/.48 is almost a perfect map to the 3b. Even a .48/.48 would be fine. A 3bt manifold with adapter and 2 oil lines with piping and your good to go. T3's are plentiful in the yard from volvos or saabs. I have a saab t3 if your interested $100. Does the 3b manifold fit the 2B?

[Dougal]

I have adapter drawings to fit a T3 onto the CT26 manifold. PM me your email address if you'd like a copy.

I also have adapters drawn up to fit the GT2052, T25 and T28's onto the same manifold. Adapters to fit the same turbos to the CT20 manifold (2LT engines etc) and T25/28 onto the T3 flange.

[BreckenridgeCruiser]

Wesintl, I'd love to see that turbo if you think it'd work on my truck. I was going to just flip the existing manifold if I couldn't find a 13bt manifold for a good price. What are the measurements/ratings of that t30?

Dougal, I'd love to see your drawing as I'd need an adapter for the garretts on either my existing manifold or a 13bt.

I'll PM both of you with some contact info.

Kraig

[Dougal]

Originally Posted by BreckenridgeCruiser

Wesintl, I'd love to see that turbo if you think it'd work on my truck. I was going to just flip the existing manifold if I couldn't find a 13bt manifold for a good price. What are the measurements/ratings of that t30?

Dougal, I'd love to see your drawing as I'd need an adapter for the garretts on either my existing manifold or a 13bt.

I'll PM both of you with some contact info.

Kraig

I've emailled you the CT26-T3 adapter drawing.