ct26 max psi

[SupraClaou]

I was pushing 14-15 psi of boost on the CT26 on my stock 7MGTE for
about 1 year without any issues! I raised the boost through an AVC-R...
Still have it with my 2j :biglaugh:
CT26 turbos are very reliable/tough turbochargers.You can raise the boost
2 times more than the stock boost is (6.8 psi to 14psi) on a 16+ years old
turbo without problem on a good condition CT26 turbo.

Wish my JDM ceramic twin turbos could hold 2 times more boost pressure
than stock (10psi to 20psi) :naughty:

One thing is 100% true about the oem CT26.....
It is useless to boost more than 14-15 psi. The volume of the boosted
air is limited on this boost level,and the pressurised air is geting to hot!

Still we must be greatfull that this turbo has the balls to play around with
it and mode it/boost it to higher levels....:biglaugh:

 

[figgie]

lilmiss...

13psi netted you 300 at the wheel (350ish)?

By chance do you have a dyno graph?

That is roughly about 33 lbs/min worth of air at a 77% VE from what you are telling me

 

[SupraClaou]

Not wanting to get involved in the discussion between Figgie and Tissimo, but to the OP and a few others, My car has all the bolt-on mods to support an upgraded turbo (injecors, fuel pump, mapecu2, custom intale, brand new upgraded cooling system etc etc etc), and when I dynoed with the stock CT26, we couldn't/wouldn't/didn't push it above 13psi, because it just fell on it's face.

13psi on stock turbo + all relevant bolt on mods = 300hp at the wheels (for me).

+10.:biglaugh: You did right!

 

[LilMissMkIII]

Figgie, it was 208.9rwkw on an Australian DynoDynamics dyno... I rounded up to 300hp, as from everything I have seen the US dynos read ridiculously higher... Just making my figures "equal" to what they would be if my car was dynoed in the US.

I'll try and scan my dyno sheet in in the next half hour or so

 

[figgie]

lilmiss thanks!

I am more concerned about the curve

 

[tissimo]

this is going to be fun!!

unfortunatly for you, pressure IS infact, closely related to flow. The exact reason why the CT26 falls flat on its face from a intake pressure point at the upper end of the RPM scale. The reason it is related to pressure because unlike a true turbine engine, The internal combustion engine creates pulse when the valves are closed which coincidentally happen to be where the valves are most of the time except for when they open to allow the cylinder to injest air. So when the valves are closed, Resistance to the flow is present and as such pressure and flow are related If the turbo can not keep up, like the aforementioned ct26... you have a reduction in pressure as the engine injest more air than the turbo can flow.

any other asumptions on your part? You best better brush up on your fluid mechanics if you are going to tackle this subject because you will not win.

No doubt pressure and flow are related, but pressure != flow. So, 20psi on a CT26 != 500 hp.

The CT26 will not maintain 20psi in the upper RPM range unless VERY drastic meassures are taken to do so.

I will not win what? Read over what you said and tell me I'm not right. PLEASE

 

[figgie]

No doubt pressure and flow are related, but pressure != flow. So, 20psi on a CT26 != 500 hp.

The CT26 will not maintain 20psi in the upper RPM range unless VERY drastic meassures are taken to do so.

I will not win what? Read over what you said and tell me I'm not right. PLEASE

You aren't.

you will never ever get to 20 psi on a stock ct26 on a 7m. On a smaller 3s engine it is within the CT26 capability but not on the 3.0L of 7m. Not even if you were to change exhaust housings etc. You are going to take the CT26 choke point and overrev the turbo beyond anything it was designed for. (and just so we are on the EXACT same page, If you bring up anything like a ct26-60-1, then you are not talking about the CT26 at that point). The same exact principal that restrictor plates use....once the flow goes sonic, no amount of vacuum will make it flow past that point.

Math to come shortly.

 

[3.0 GT]

You aren't.

you will never ever get to 20 psi on a stock ct26 on a 7m. On a smaller 3s engine it is within the CT26 capability but not on the 3.0L of 7m. Not even if you were to change exhaust housings etc. You are going to take the CT26 choke point and overrev the turbo beyond anything it was designed for. (and just so we are on the EXACT same page, If you bring up anything like a ct26-60-1, then you are not talking about the CT26 at that point). The same exact principal that restrictor plates use....once the flow goes sonic, no amount of vacuum will make it flow past that point.

Math to come shortly.

thanks for all the replies! ill stay in the 14-15psi range probably and work on other intake/exhasut mods after i pay off some debt lol

 

[Boost Lee]

You aren't.

you will never ever get to 20 psi on a stock ct26 on a 7m. On a smaller 3s engine it is within the CT26 capability but not on the 3.0L of 7m. Not even if you were to change exhaust housings etc. You are going to take the CT26 choke point and overrev the turbo beyond anything it was designed for. (and just so we are on the EXACT same page, If you bring up anything like a ct26-60-1, then you are not talking about the CT26 at that point). The same exact principal that restrictor plates use....once the flow goes sonic, no amount of vacuum will make it flow past that point.

Math to come shortly.

I enjoy the frequent "debates" between yourself and tissimo.
They're argumentative, yet educational for others.

To add to this, I HAVE seen a stock CT26 hit beyond 20PSI.

..........It ate itself.

One thing that actually just hit me...
suprarich...I'm sure you're familiar with, ran his MA70 with a stock CT26 @ (IIRC 20PSI) and Nitrous, to pull of an 11.95 E.T.
I don't know if this turbo survived or even made it for the trip back home for that matter, but I believe it was a solid 20PSI.

I do understand what you're saying though (I promise)
A CT26 WILL NOT survive with that amount of boost.
I don't care what anyone else says. They. Just. Can't. Do it.

But it has been done. I've got far too many CT26 failure stories for everyone if you'd like to hear.

Jeff

 

[Boost Lee]

thanks for all the replies! ill stay in the 14-15psi range probably and work on other intake/exhasut mods after i pay off some debt lol

For the life of me (and your turbo)...

Get some kind of 3" exhaust (or anything less restrictive) so that at 1 bar, you're turbo doesn't choke.

 

[figgie]

To add to this, I HAVE seen a stock CT26 hit beyond 20PSI.

..........It ate itself.

One thing that actually just hit me...
suprarich...I'm sure you're familiar with, ran his MA70 with a stock CT26 @ (IIRC 20PSI) and Nitrous, to pull of an 11.95 E.T.
I don't know if this turbo survived or even made it for the trip back home for that matter, but I believe it was a solid 20PSI.

Lol Jeff

I would be curious to see the pressure ratio at that level.... my guess 5+ on the comp side and and astronomical on the turbine side.

 

[tissimo]

You aren't.

you will never ever get to 20 psi on a stock ct26 on a 7m. On a smaller 3s engine it is within the CT26 capability but not on the 3.0L of 7m. Not even if you were to change exhaust housings etc. You are going to take the CT26 choke point and overrev the turbo beyond anything it was designed for. (and just so we are on the EXACT same page, If you bring up anything like a ct26-60-1, then you are not talking about the CT26 at that point). The same exact principal that restrictor plates use....once the flow goes sonic, no amount of vacuum will make it flow past that point.

Math to come shortly.

You're talking about 20 psi @ 6500 rpms correct? I assume so, I even doubt that will be possible. But if you weld the wastegate shut so ALL exhaust gas passes through the turbine I think it will make 20psi @ 6500 rpms. The exhaust back pressure will probably be 20:1 and thus the flow through the engine will be minimal allowing for the CT compressor @ 250k rpms to create 20 psi of intake pressure. Then promply blow into 500k peices. LOL

But even if it does make 20psi, the flow would be cut down SO much from the EXTREME backpressure on the engine it would be No where near 500hp. you MIGHT be able to break 400 if you had a BIG enough intercooler to take the heat out of the 20% efficent compressor @ 250k rpms. Pressure != flow.

Of course all those numbers are pulled directly out of my ass.


Suprarich ran his stock CT26 @ 20 psi for over 200 passes he has said. I saw him run the car SEVERAL times @ tx2k7 which included a 12.7 @ 105mph pass no nitrous. I'm sure the boost fell down to 15 psi or so at redline with the car, but it did make 20 psi in the lower end (unless he was lying). I've personally boosted 18 psi on the lower end with a CT26 (manual boost controler set too tight).

 

[Sawbladz]

FIGGIE: This is my stock turbo 7M at about 12 psi. It falls to under 10 by redline. Probably similar curve to Lil Miss'

 

[NashMan]

15 psi and it will not last long

 

[Keros]

You're talking about 20 psi @ 6500 rpms correct? I assume so, I even doubt that will be possible. But if you weld the wastegate shut so ALL exhaust gas passes through the turbine I think it will make 20psi @ 6500 rpms. The exhaust back pressure will probably be 20:1 and thus the flow through the engine will be minimal allowing for the CT compressor @ 250k rpms to create 20 psi of intake pressure. Then promply blow into 500k peices. LOL

Sounds like you guys are disagreeing to agree... i.e. trying to say the same things in different words from different perspectives, and not really understanding it. I think one thing that's misunderstood here is that boost pressure does NOT make horsepower and flow does make horsepower, but pressure and flow are directly related (one cannot exist without the other). Think of it like this: Flow 2 gallons/min of water through a 1" hose, and then flow 200 gallons/min of water through that same hose. Of course, the 200 gallons/min of water is going to produce massive ammounts more pressure than the 2 gal/min example.

However, in engine terms, consider that example in terms of air; thusly, the amount of air flowed is vindicative of the horsepower generated, as Figgie has already said (whether it's a 4g63, 7M, 302, or 426... at the same VE, it takes the same amount of air to make the same horsepower). In the same breath of writing, he also said that the pressures in the manifold are different, correlating to the displacement of the engine. This is because a 3L will require the air to be compacted into the cylinders in order to produce the same horsepower from the same air volume as a 426 V8. So thus, we conclude that boost pressure does not produce horsepower, but the volume of air flowed does. However, as flow increases in the same volume of space, the pressure in that space will increase as a result. Since 'boost pressure' is pressure in the manifold, the manifold is the space in question... flow more air through it to make more horsepower, get more pressure. You see where this is all going. All that extra air has to go somewhere, so it packs closer together.

I gather from what Figgie is saying, is that the CT26 cannot make 20psi on a 7M that's sucking in air from it because the turbo won't make enough flow to overcome what the engine is sucking up. Attempting to do so by modifying the wastegate would kill the turbo by exploding the turbine, compressor wheel, or bearings. Little turbo, medium sized engine... something would break.

No one tell Figgie that this is all just a ploy to wring his knowledge out onto the forum though :icon_bigg

 

[NashMan]

but i have read about this one guy pushing 20 psi on stock ct befor but there were useing spray aka makes shit get cold

plus if remmber right 480 hp or some thign liek that this is going back like many years ago

 

[Doward]

I was going to reply to this before I left to tune Jeff's car, but decided against it.

Keros - *clap* Bravo, my man.

 

[zambini]

so hey im in pretty much the same boat as the original poster:

aside from whether or not the stock ct is capable of 20psi, for whatever amount of time,

and aside from the differentiation of flow and boost pressure...

we know what were flowin with and what were flowing into here: stock rebuilt blocks with all new gaskets, yet were also using a 20 y/o turbo. now, assuming the turbo is in relatively good shape, do you all think its safe and reliable to flow 12psi on the daily? im assuming i couldnt hit anything above 12 right now due to fuel cut, and i really wouldnt go any higher anyway for fear of limited turbo life. but does 12psi sound reasonable to everyone here? driving somewhat conservatively, giving it a little throttle here and there, never redlining it, rarely racing it...

should i go with 10 or 12? i guess the obvious answer is that flowing less boost is gonna make the turbo last longer period.. but would you call 12psi a feasibly reliable dd boost level?

thanks guys.

aaron

 

[LilMissMkIII]

Just realised my dyno sheets are on my desk at work... Will scan them in and post them up when I get to work on Monday morning.

 

[Zumtizzle]

whats a CT26?