[Mk2] [Turbo] CT26 vs CT20...

[djpkins]

Now...I know what your going to say...CT20 is more powerfull and torquey...and I would agree that lower rev range, the ct20 pulls better...but I've just changed from CT26 to CT20 and am struggling to make full boost.
On my old turbo, AVCR set to 1.2bar at 69% duty cycle would cream 1.2bar and on a crisp eve would spike at 1.4ish @6k rpm...the CT20 is making, at most so far, 1.07bar @6k rpm and in no way is it as quick as the old CT26...in fact the car seems lumpy at anything over 67% duty cycle now


I inherited the CT26 with the car so I don't know what,if any, work has been done to it...it has a pen mark on the shaft and has visable signs of tool marks on the nut...has A3-10 marked on the top???
The new CT20 had chipped blades, but not hanging off, surely this wouldn't affect boost so much?

[Slarty]

Chipped blades on which side, hot or cold? The CT20 on my car (standard bar a steel shaft) has no problems whatsoever hitting over 1.1 bar, infact while having problems it managed to spike to 1.4

[jon_st205]

Remember that there are different flavours of CT20b too, ceramic + steel etc. It's also not just about boost pressure but about air flow, in which the 20b will have the advantage over the 26.

If you're struggling to hit your target boost I would look at the actuator and wastegate operation; take the DP off and use an air pump. The 20b's are known for cracking around the wastegate area which will reduce the ability to hold boost.

Cheers,
Jon

[djpkins]

chipped on the cold side...but not much...biggest bit would be about 2sq mm...thanks for the reply guys...if it has to come off, so be it, although it came from a very safe source and was all good on it's last car...wouldn't I smell the leak if there was a crack?It's a ceramic job I assume, there was no hole in the centre of the exhaust wheel like in the pic of the 26 ...lol..this 20 was supposed to tide me over untill I can get something bigger...and truth be told, I rarely go above a ton, just into banging it around the lanes, thought the CT20 might even do the job completely...my mates rev3 seemed bonkers quick pulling 295 with a 20b on it...this blower was the first in a long list of bits that I plan to replace to bring it back to form, the leads are suspect and need to be replaced...and I have the bits to make a copper tabbed dizzy cap...my plugs were coked up to hell when I checked earlier on and there is a defianate misfire now I've pulled the leads about...where do we go for leads? oem is the way forward isn't it?

[djpkins]

Correct me if I'm wrong...but doesn't the hilux srf use a ct20 that produces much lower boost levels? smaller comp wheel?

[T.F.S.]

chipped on the cold side...but not much...biggest bit would be about 2sq mm...thanks for the reply guys...if it has to come off, so be it, although it came from a very safe source and was all good on it's last car...wouldn't I smell the leak if there was a crack?It's a ceramic job I assume, there was no hole in the centre of the exhaust wheel like in the pic of the 26 ...lol..this 20 was supposed to tide me over untill I can get something bigger...and truth be told, I rarely go above a ton, just into banging it around the lanes, thought the CT20 might even do the job completely...my mates rev3 seemed bonkers quick pulling 295 with a 20b on it...this blower was the first in a long list of bits that I plan to replace to bring it back to form, the leads are suspect and need to be replaced...and I have the bits to make a copper tabbed dizzy cap...my plugs were coked up to hell when I checked earlier on and there is a defianate misfire now I've pulled the leads about...where do we go for leads? oem is the way forward isn't it?

OEM are good, as are magnecor, best to check leads for resistance if funds are tight

[djpkins]

I seem to be coming up with mixed results on the rsisitance test...

my good rev 3 king lead shows no resistance...lol...but ALL 8 of my other leads are showing around 1500-1700.
I get different readings depending on whether the probes are attached to the metal tips on the HT leads or pushed right into the wells.
New leads has to be a good move, I know the rest of the electrical ignition components to be good and tested...if I think about it...I stood on them when I was removing the turbo...I had a fiddle with them earlier and the car was propperly misfiring on anything other than tickover, but the narrowband afr was doing it's merry dance as opposed to being stuck on rich all the time when I had overfuelling probs...so fk it..happy days just around the corner with a new set of leads

[Baker]

Try the ngk leads, 50 quid and of good quality.

[bobhatton]

Correct me if I'm wrong...but doesn't the hilux srf use a ct20 that produces much lower boost levels? smaller comp wheel?

A CT20 is not the same turbo that is fitted to a Rev3.
The Rev 3 and ST205 have what is called a CT26 Small, but everyone calls them a CT20B.

If you have damage to the comp wheel the turbo is scrap. It will not boost well, will be out of balance and will not last long. No one makes replacment comp wheels for that turbo

[Driftlimits Performance]

2mm square is HUGE!!!!

I'm with Bob put it in the bin.

out of balance turbo, potential engine write off.

[djpkins]

Ok...Thank for the heads up guys..didn't realise they were so finely balanced...well..I may have suspected it it wasn't gonna be a permenent replacement with damaged blades and it was passed on to me for a very good price so , thus far, nothing has been lost...the amount of clean oil that the old ct26 was blowing through, started to pool a bit in the pipework and there is just the startings of blade marks in the housing...no smoke at all, just fresh oil been blow through the system...can it be fixed with a DIY kit? or is it a pen holder?

[bobhatton]

Ok...Thank for the heads up guys..didn't realise they were so finely balanced...well..I may have suspected it it wasn't gonna be a permenent replacement with damaged blades and it was passed on to me for a very good price so , thus far, nothing has been lost...the amount of clean oil that the old ct26 was blowing through, started to pool a bit in the pipework and there is just the startings of blade marks in the housing...no smoke at all, just fresh oil been blow through the system...can it be fixed with a DIY kit? or is it a pen holder?

Yes, I have rebuild kits from them

[turbotrouble]

Correct me if I'm wrong...but doesn't the hilux srf use a ct20 that produces much lower boost levels? smaller comp wheel?

A CT20 is not the same turbo that is fitted to a Rev3.
The Rev 3 and ST205 have what is called a CT26 Small, but everyone calls them a CT20B.

If you have damage to the comp wheel the turbo is scrap. It will not boost well, will be out of balance and will not last long. No one makes replacment comp wheels for that turbo

your wrong and wrong again i can get u any comp wheel u like

[turbotrouble]

2mm square is HUGE!!!!

I'm with Bob put it in the bin.

out of balance turbo, potential engine write off.

why is it a potent write off.... the ceramic bits wont get past the inter cooler. i have popped loads luke?

[bobhatton]

Correct me if I'm wrong...but doesn't the hilux srf use a ct20 that produces much lower boost levels? smaller comp wheel?

A CT20 is not the same turbo that is fitted to a Rev3.
The Rev 3 and ST205 have what is called a CT26 Small, but everyone calls them a CT20B.

If you have damage to the comp wheel the turbo is scrap. It will not boost well, will be out of balance and will not last long. No one makes replacment comp wheels for that turbo

your wrong and wrong again i can get u any comp wheel u like

Great. Can I have a price for 5 CT20B comp wheels please together with a sized drawing of the wheel

[bobhatton]

2mm square is HUGE!!!!

I'm with Bob put it in the bin.

out of balance turbo, potential engine write off.

why is it a potent write off.... the ceramic bits wont get past the inter cooler. i have popped loads luke?

You are right the ceramic bits will not get past the intercooler as they are on the exhaust side of the turbo.

[turbotrouble]

no the shaft on mine is ceramic with metal wheels

[bobhatton]

no the shaft on mine is ceramic with metal wheels

You must have a one off turbo then, never seen one like that and can see no point to it.
The reason the turbine wheels are ceramic is to reduce weight and bring the turbo up to boost as early as possible, what is a ceramic shaft going to do?