Boost maps, CT20b, CT26.

[RedMist]

Just rebuilt my CT20b however I'm having some serious doubts in regards to pumping so much air through a 36mm restrictor. A cheap option may be to just to replace it with a suitable CT26 steel wheel.

As such does anyone have the boost maps for the CT20b or CT26?

[Dell'Orto]

I believe they're hidden in an underground lair below Toyota HQ, patrolled by dragons and goblins.
Pretty sure even fivebob doesnt have them

[Phothog]

Just rebuilt my CT20b however I'm having some serious doubts in regards to pumping so much air through a 36mm restrictor. A cheap option may be to just to replace it with a suitable CT26 steel wheel.

As such does anyone have the boost maps for the CT20b or CT26?

You would be going backwards.
the Gen1/2 Celica / MR2 CT26 has a 42.5mm inducer compressor wheel,
where as the Gen3 Celica / MR2 CT20b has a 48mm inducer compressor wheel.

and the turbine on the CT26 is 51.92mm exducer
where as the CT20b Steel is 48mm exducer (Ceramic is 50mm)

the Evo's & subbies have had no problem pulling air through a restrictor for the past 12+ years..

in fact the Evo's have changed in the years but the turbos have stayed the same compressor & turbine wheel sizes.. (except the 6.5 GSR & 8 Gsr they have a "Hi responce" compressor wheel which is not holomogated for rally use.)

Chris.

[RedMist]

Just rebuilt my CT20b however I'm having some serious doubts in regards to pumping so much air through a 36mm restrictor. A cheap option may be to just to replace it with a suitable CT26 steel wheel.

As such does anyone have the boost maps for the CT20b or CT26?

You would be going backwards.
the Gen1/2 Celica / MR2 CT26 has a 42.5mm inducer compressor wheel,
where as the Gen3 Celica / MR2 CT20b has a 48mm inducer compressor wheel.

and the turbine on the CT26 is 51.92mm exducer
where as the CT20b Steel is 48mm exducer (Ceramic is 50mm)

Its spooling the thing that I'm most worried about. If I can spool it very early in the rev range I wont require anywhere near the volume of air past the restrictor. Its been a while since I've driven a CT26 powered car, but from memory it spooled considerably quicker than the CT20b. Am I totally wrong in my assumptions?

[fivebob]

Its spooling the thing that I'm most worried about. If I can spool it very early in the rev range I wont require anywhere near the volume of air past the restrictor. Its been a while since I've driven a CT26 powered car, but from memory it spooled considerably quicker than the CT20b. Am I totally wrong in my assumptions?

IME the CT20B spools quicker than the CT26, but that is based on my experience with the ceramic versions of bot turbos.

I know a CT20B will produce boost from about 1800rpm, and it can produce 1 bar by 2800rpm. Funnily enough the modified CT20B (Blitz K1-380V), which was steel shaft, could produce 1.4bar by 2900. Though it didn't start boosting till about 2000rpm.

As for finding compressor maps, in 14 years of playing with 3S-GTE's I've never seen one, I doubt they exist, of if they did the goblins probably ate them

[RedMist]

Sounds like there is something seriously wrong with my ST205 road car (other than the TD04 steel wheel) ... as its not spooling till about 3k RPM

[KinLoud]

I don't know if these are the maps you are after but look here...
http://www.rbracing-rsr.com/turbotech.html

Some good info anyway - now we need a guide on how to use the info...

Ken
Ham
021 408 863