Ct9 Hybrid

[speedvision]

would the CT12 compressor wheel fit if the stock CT9 housing is bored? and what does the term "cut back" refer to? thanks

the ct12 wheel and the ct9 wheel is prob the same size..u will get no gains

cut bac wheel is the turbine wheels cut at an angle i believe to aid spool up faster..not really needed in my opinion as the ct9 wheel is already small and will spool pretty fast

sam

 

[TurboDave]

The cut back is to remove some restriction of the turbine wheel at higher rpm and aid quicker airflow. A cut back helps to hold boost at higher rpm.





Dave

 

[Toplap]

Hmm...good to know thanks Dave and Sam.


Danny

 

[ivan]

CT12a or CT12b and CT9 are not the same size wheels, not by a long shot!

For anyone in the USA and wants a great turbo, do the following.

Get a rear housing off a CT9, thats all you need. Then get a ct12b turbo off a US spec Supra. This is because the US Spec supra comes with a steel rear wheel.

Now you get the rear housing machined so it has 1.3mm clearance between the wheel and inner wall of housing.

Once that is done clean up the wastegate port with a dyegrinder and assemble turbo togheter. A machine shop will charge you bugger all to machine the rear housing.

Put it together and you are done. Note you may have to linish back the compressor housing a little bit as the oil filter relocater may foul on it. You can do it so there are a couple of mm clearance and still plenty of alloy on the housing.

Hope that help ppl.

ivan

 

[Enzo]

is 200bhp the most you can get out of a Hybrid??

i think memory a guy on here got 221bhp at 1.2 bar on a rev2 g-spec hybrid but dont quote me on that as id have to traul the old site to look for the dyno print out.

rev3 gt spec hybrids with a different compressor wheel to the rev2 are capable of 220bhp + @ 1.2 bar
check here for spec and comparisions

link to hybrid

 

[Toplap]

CT12a or CT12b and CT9 are not the same size wheels, not by a long shot!

For anyone in the USA and wants a great turbo, do the following.

Get a rear housing off a CT9, thats all you need. Then get a ct12b turbo off a US spec Supra. This is because the US Spec supra comes with a steel rear wheel.

Now you get the rear housing machined so it has 1.3mm clearance between the wheel and inner wall of housing.

Once that is done clean up the wastegate port with a dyegrinder and assemble turbo togheter. A machine shop will charge you bugger all to machine the rear housing.

Put it together and you are done. Note you may have to linish back the compressor housing a little bit as the oil filter relocater may foul on it. You can do it so there are a couple of mm clearance and still plenty of alloy on the housing.

Hope that help ppl.

ivan

Very interesting? any links to said Hybrid? i have located a set of CT-12 a's from a 1G-GTE that could help. though i would want to locate another CT-9 as well to be safe

 

[TurboDave]

Having a massive compressor wheel and a standard turbine wheel is ridiculous.

How is it supposed to expell the extra air sucked in by the compressor wheel?

 

[Timmy]

that comment makes no sence. You hardly see any modifed exhaust side wheels on ct9 hybrids. And if you made it bigger you'd get more lag.

 

[TurboDave]

It makes perfect sense I run a bored turbine housing with a larger turbine wheel and I create boost below 2000rpm and hold 1.2 bar to the limiter, So I hardly call that laggy.

If for one second you think that such a large compressor wheel and a small turbine wheel is a good match then you must be out of your mind. How is the mass of air induced from the large compressor wheel supposed to exit the turbo through the small turbine wheel?

 

[Guye]

The turbine wheel only sees exhaust gases and nothing else. So with the small turbine wheel you only need a small amount of exhaust flow to get it spinning. The turbine wheel is connected to the now larger compressor wheel by the shaft. The larger compressor wheel being driven by the quick spooling turbine wheel give the benefits of quick response + greater air flow (larger compressor wheel = more air moved per revolution). The air from the larger compressor wheel exits via the compressor housing outlet to your ic piping, not through the turbine wheel. The only limitation may be how much of the existing compressor housing can sensibly bored out, and if the larger compressor wheel can still be balanced on the shaft when assembled.

 

[TurboDave]

The turbine wheel only sees exhaust gases and nothing else. So with the small turbine wheel you only need a small amount of exhaust flow to get it spinning. The turbine wheel is connected to the now larger compressor wheel by the shaft. The larger compressor wheel being driven by the quick spooling turbine wheel give the benefits of quick response + greater air flow (larger compressor wheel = more air moved per revolution). The air from the larger compressor wheel exits via the compressor housing outlet to your ic piping, not through the turbine wheel. The only limitation may be how much of the existing compressor housing can sensibly bored out, and if the larger compressor wheel can still be balanced on the shaft when assembled.

So when the air exits through the compressor housing it then magically disapears?


The larger mass of air is then used in the clyinders and then is restricted from exiting the cylinders due to the small turbine wheel and exit housing, causing heat back up and may be one of the reasons why these turbos fail when they see some boost.

 

[Guye]

So when the compressed air exits through the compressor housing it then magically disapears?


The larger mass of air is then used in the clyinders and then is restricted from exiting the cylinders due to the small turbine wheel and exit housing, causing heat back up and may be one of the reasons why these turbos fail when they see some boost.

Remember one of the first recommended requirements for a hybrid is to upgrade the exhaust manifold. I'm sure that you are well aware that even with a stock ct9 @ 1bar the restriction in the 3rd runner causes the senario you mentioned, the same will obviously happen with a larger compressor wheel moving more air. A small turbine wheel is not the huge restriction you seem to imagine it is. The small turbine wheel means that an engine with a low volumetric efficiency i.e. 1300cc can still spool the turbine at low rpms. Adding a larger turbine wheel will mean you have a larger restriction to the exhaust gases exiting, requiring more exhaust gases to turn it (larger turbine, longer spool time, more lag) That is why the turbine is kept as stock and only the compressor wheel is enlarged. I have noticed with my hybrid insted of there being a restriction hampering exhaust flow, it now spools and make boost from 1100rpm. A restrictive turbine will not do this.

 

[Adam_Glanza]

good thread guys

 

[TurboDave]

Remember one of the first recommended requirements for a hybrid is to upgrade the exhaust manifold. I'm sure that you are well aware that even with a stock ct9 @ 1bar the restriction in the 3rd runner causes the senario you mentioned, the same will obviously happen with a larger compressor wheel moving more air. A small turbine wheel is not the huge restriction you seem to imagine it is. The small turbine wheel means that an engine with a low volumetric efficiency i.e. 1300cc can still spool the turbine at low rpms. Adding a larger turbine wheel will mean you have a larger restriction to the exhaust gases exiting, requiring more exhaust gases to turn it (larger turbine, longer spool time, more lag) That is why the turbine is kept as stock and only the compressor wheel is enlarged. I have noticed with my hybrid insted of there being a restriction hampering exhaust flow, it now spools and make boost from 1100rpm. A restrictive turbine will not do this.

Yes but the 3rd runner isnt as bad as everyone makes out granted it is restritive when running high boost and a larger volume of air however it wouldnt and hasnt been on the top of my list and I now run a ported standard manifold with no problems. A larger turbine wheel would mean more gas is needed to turn it in order to spin the compressor wheel and to create boost however with a compressor wheel as large as 55mm that shouldnt be a problem. I would bet my right arm that these turbos will not hold high boost to the redline due to the simple fact the exhaust turbine housing (non bored) and small turbine wheel (not with a clip either) wont be large enough to flow the amount of air induced by the large compressor wheel.

Do you run one of these turbos?

Dave

 

[Timmy]

They will hold about 1 bar to the redline maybe 1.2 if your lucky. (this is based on the fact that this what ct9 hybrids without the turbine changed) And that the efficentcy range of these turbo's You could give it a bigger turbine wheel and it will hold 1.6bar to the redline but this is out of the efficentcy range so all you have suceeded in doing is increasing lag and not producing any extra power.

 

[speedvision]

most of the hybrids i have seen held 1.2 bar to red line with uprated acutator ofcourse.....and all of them have had the wastegate bored out with a bigger flap and just left the turbine wheel and turbine hole stock.......sam

 

[Guye]

Yes but the 3rd runner isnt as bad as everyone makes out granted it is restritive when running high boost and a larger volume of air however it wouldnt and hasnt been on the top of my list and I now run a ported standard manifold with no problems. A larger turbine wheel would mean more gas is needed to turn it in order to spin the compressor wheel and to create boost however with a compressor wheel as large as 55mm that shouldnt be a problem. I would bet my right arm that these turbos will not hold high boost to the redline due to the simple fact the exhaust turbine housing (non bored) and small turbine wheel (not with a clip either) wont be large enough to flow the amount of air induced by the large compressor wheel.

Do you run one of these turbos?

Dave

I'm using a ct9/ct20 hybrid. I think I see the source of the confusion. The turbine wheel on the exhaust side is left stock. It makes no sense to put a larger turbine wheel on a ct9 since that will create lag. On larger turbos the turbine is larger than a ct9's but so is the compressor wheel. Ballbearing turbos have been created to counter the inherent flaw where it takes longer for the larger turbine to spool, but at the same time the power increase is greater because the larger compressor wheel induces more air per PSI into the cylinders (increased airflow per pressure). The essence of a hybrid is to try to get the best of both worlds. Small turbine with quick spool + larger compressor wheel capable of greater airflow = one decent upgrade over a stock ct9 without sacrificing response. The wastegate housing will have to be bored to prevent boost creep. This is because the increase gases flowing through the cylinders as you mentioned, now have to be efficiently diverted away from the small turbine otherwise it spins progressively faster as rpm builds. This causes the compressor wheel to spin faster as well (the two are connected) and boost creep results. Most hybrids I have seen offered for sale have had the wastegate ported by the makers. This is also a basic requirement for the hybrid to work properly.

 

[Toplap]

this is a very interesting debate

 

[ep_chen]

Having a massive compressor wheel and a standard turbine wheel is ridiculous.

How is it supposed to expell the extra air sucked in by the compressor wheel?

the exhaust fan does not EXPELL gases. It is there to make use of the otherwise wasted kinetic energy from outgoing gases destines to be wasted through your exhaust system. these gases pass the exhaust fan propel the fan which in turn propels the compressor fan connected through a shaft to suck in massive air pressure and forced to the engine. that is why turbocharging/supercharging is called FORCED INDUCTION.

 

[TurboDave]

The exducer wheel on the turbine side is also designed to suck as it spins and therefore exude/exduce ( http://thesaurus.reference.com/search?r=20&q=exude) (eg emit, flow out, ooze) as it spins so the turbine wheel in fact is also sucking the air out of the cylinders as it spins the compressor wheel and forces pressurised air into the cylinders.


It makes perfect sense to put a larger turbine wheel on and bore the housing due to the fact IT IS NOT LARGE ENOUGH TO EFFICENTLY FLOW THE LARGER VOLUME OF AIR, hence it not being able to hold high boost.

Timmy, If the turbo is still compressing the air to say 1.2 effectivly then the intercooler will cool the charge anyway.