Advantages on supra turbo ct26 over alltrac ct26?

smog7

Moderator
ok cool. thanks for the info guys.. would i have to upgrade anything with the addition of a ct20b? or is it simply plug and play?
 

smog7

Moderator
also is anyone currently using a cr20b? i did a quik search and read that the st205 turbo is not labeled ct20b.... whats the actual history on this turbo?
 

db

Active member
The CT20b has a seventh stud that needs to be removed to work with the second gen downpipes and stock cat elbows. Completely plug and play otherwise.

The CT20b was never formally called that by Toyota, but that's what the Toyota crowd calls it. It came on the ST205 and the last generation of MR2 turbos overseas.

Many MR2 guys use it, but not so many of us.
 

tw2

New member
Yes everything came with a ct26 except the st205's which came with ?ct20b? ct20's are hard to find, expensive and not worth it plus they also came with the ceramic wheel which will happily shatter at high boost. I personally would either get the ct26 rebuilt for a long happy reliable life or just get a proper large turbo t3/t4 etc with upgrades in mind for the future. I do not see the value in ct27 ct20 upgrades unless they are going to be the same as having the ct26 rebuilt. Just one opinion.
 

allblackalltrac

New member
I have to agree 100% with tw2.
CT20B and CT27's are over rated and over priced.
The current going market for CT20b's is $600+
A year ago they were selling for $500
CT27's start at $900 with a core exchange!
Im sorry but for that price I can find t3/t4, or buy TWO freshly rebuilt ct26's

But enough about those turbo's this thread is about CT26's
CT26A from the 7MGTE motor found in the Supra MA70.
The "A" denotes the CT26 from the Supra, its cast directly into the turbine housing.
It is a single entry turbo and capable of 300hp and unlike the ct26 found on the MR2 and AllTrac, boost will not start to fall off at high RPMs and is capable of producing more efficent boost beyond 16psi.
It is also a direct bolt on for the 1G3SGTE, with only the need the clock the center cartrige and impeller housing - the exducer housing bolts to the single entry manifold and turbo elbow of the 1G3SGTE.
Low milage CT26A can be purchased for as little as $100 and rebuilds for $400.
Several turbo rebuilders also offer upgrades of the CT26A the most notiable upgrade being the T4 60-1 capable of 500+hp
This upgrade actually replaces the center cartrige with a Garret unit and if you are resourceful enough can find one for as little as $700 all the while retaining that "factory" appearance.
 

tw2

New member
alltrac7":1upgfz27 said:
Sorry I do not know how much you know but...... if you are thinking of getting a bigger turbo since you need one anyway you should probably do a bit of research. You should definitely learn to read a compressor map so you can understand how a given turbo will respond and how all the trade off's work. This is a start http://www.gnttype.org/techarea/turbo/turboflow.html also http://www.stealth316.com/2-3s-compflowmaps.htm Obviously it is based around the mitsubishi gto but the principals are the same. The stock ct26 is round about a T3 40 to 44 trim i think i read somewhere just for comparison. If you pm me I can also send you a basic excel spreadsheet which will allow you to calculate all the values needed to use a given compressor map. There are also turbine maps which are very important but these are almost completely unavailable or do not exist. Garrett have some grude ones for their turbos but they are incomplete and not very useful.
40trimT3similartoct26.gif
The ct26 is slightly "bigger" than this map
 

tw2

New member
My approach to choosing a turbo is

1) decide what is important; ie fast spool, high top end, mid range torque etc
2) guestimate a possible turbo and find its compressor map or similar
3) see if it will fit your needs on paper, look at different trims as well
4) no doubt you will not find a turbine map; otherwise helpful in selecting an appropriate hot side A/R which will affect spool quite a lot
5) there is lots of info on mr2oc on how various turbo's perform for people- read up, boost threshold (rpm when starts to make positive pressure) is quite useful
6) also finding dyno plots of the turbo on various cars- obviously important to look at what other mods they have done especially volumetric efficiency improving mods. ie t3/t4 57 trim requires improved VE (cams etc) to sit properly in its efficiency range (in this case not surge around 18psi i think it was reported) whereas the 46 and 50 trims are fine.
7) then you should have a pretty good idea how a turbo will work out for you.
 

maxaud

Active member
also, if looking for a CT20b, don't accidentally purchase a regular ct20 because it's a good deal, The older Toyota Trucks used ct20's and they are quite a bit smaller. They were used on the 22re making it a 22rte, also heard of a 22rtec and 22ret, though some may just be the same engine call'd different things.

I had one for my Toyota Truck, but I sold the set-up to a guy that was building a mini-truck.
 

smog7

Moderator
what type of turbo do most of you people use then?? do most of you still have the stock ct26? how many have rebuilt ct26's?
 

tw2

New member
I get the impression that most people on the forum still have the stock ct26. A few have the ct27 and the ct20b. It is quite a lot of work to custom fit the turbo of your choice. The bolt on kits from KO, ATS etc are good value for money but none the less are very expensive for most people. I personally still have my stock ct26 (I have done custom turbo upgrades on other cars). I personally will use a t3/t4 50 or 57 trim (with cams) when I am no longer reliant on my car as my sole means of transport (im at uni).
 

smog7

Moderator
im leaning more towards just rebuilding my ct26....i still dont have to worry about for a while though....
 

tw2

New member
It is probably the safest, most reliable option. You can always upgrade later in the future, a rebuilt ct26 will still be worth something. If you get a 46 trim wheel or something put in it you might get another 10hp or somethng anyway.
 
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