[Rainz]

Well what do you think would be the best sized turbo for the 2.4L Ecotec. I'm somewhat turbo illiterate, I can't read those turbo graph things. I read a whole page on it still not understanding them. I know what a turbo does but what would be the best sized turbo? I would most likely buy a Garret turbo, knowing from friend's experiences and good quality. Just exploring the options, definetly would be a custom setup because it's alot cheaper than a turbo kit.

 

[2KWK4U]

From my limited knowledge/understanding I'm going to say you'll want a small turbo for this car. With the high factory compression ratio, you won't be able to cram much extra air down its throat anyway. So you won't need to blow over say 9 PSI max. The larger compressors are good for moving more air, but turbo lag grows exponentially with compressor size. I'd stick to a small turbo and consider having the wheels polished to try and eliminate lag.

 

[glh]

From my limited knowledge/understanding I'm going to say you'll want a small turbo for this car. With the high factory compression ratio, you won't be able to cram much extra air down its throat anyway. So you won't need to blow over say 9 PSI max. The larger compressors are good for moving more air, but turbo lag grows exponentially with compressor size. I'd stick to a small turbo and consider having the wheels polished to try and eliminate lag.

Wheels polished? What wheels are we talking about.

 

[2KWK4U]

Wheels polished? What wheels are we talking about.

I'm talking about the compressor wheel mainly. Think of it as a little fan. There is one in the exhaust stream, and it is attached to the one in the intake stream, which is the compressor wheel. With these wheels polished there is less turbulence. The air moves more efficiently, and there are no "hot spots" around surface irregularities. I believe the inside of the compressor housing can be polished as well.

 

[Jus2shy]

Ugh, I was about to go into a whole technical spiel about turbo's... but most of it would just go over the heads of many people. What I can do though, is read a good primer book on turbos. Mainly, read Maximum Boost by Corky Bell. Its a great primer, and will teach you how to setup and size what kind ot turbo to have and such. You may actually want a larger turbine wheel with the turbo, if the bottom end is kinda weak. That way the turbo spools up later in the RPM range putting less torque out, saving your connecting rods, and still allowing you to make goo power. Or if the bottom is strong, you may want a smaller turbine, and a larger intake housing. Etc etc etc.... lots of factors when considering a turbo. Personally, I'd go Turbonetics, their ball bearing turbos are just fantastic. But garrett has been in the industry for a long time as well, and has a fantastic ball bearing center section as well.

 

[glh]

Thanks for the info.Sounds like a good read, i'll check it out.

 

[faultline]

I have a custom turbo set up on my Pontiac Vibe . It is a 1.8 liter motor with a 10:1 CR. I have garrett T3 turbo. The compressor housing is a large ar60, the impeller is like a .42 trim and the turbine is 48?? if forget. it works beautifully. Anyway, I would like to get something like a gt35 for this 2.4 solstice motor. It is big. yet, I like bigger than recommended turbos because:
1. they dont have to work so hard..will last longer.
2. They dont heat up as much for working less hard, the charge air is cooler.
3. They move lots of air into the motor at a lower psi.. than a small turbo can.
4. Even though you only get boost in the upper half of the power band, it is good enough. it's where most 4 bangers make good power anyway.
5. Recipricate my 4 points and realise that smaller turbos spin very fast, and create a lot of heat..heating up the oil, and intake temps. They often poop out at the high end for lack of air, even though they cover a broader powerband. ...Smaller turbos are harder to tune IMO...

 

[CMF]

On a 2.4L engine the T3 would help with torque big time and will be good up to about 260-280hp with about 10-12psi.

Lag wouldnt be a big issue with the T3 however i would like to see this car with maybe a T28. It spools a lot faster then a T3 and makes just about the same power.

Anything over 300HP you will need either a T3 with a custom trim or go to a bigger sized turbo.

I am actually going to be getting the Sky and make a turbo kit for it so i guess we'll wait and see.

 

[faultline]

On a 2.4L engine the T3 would help with torque big time and will be good up to about 260-280hp with about 10-12psi.

Lag wouldnt be a big issue with the T3 however i would like to see this car with maybe a T28. It spools a lot faster then a T3 and makes just about the same power.

Anything over 300HP you will need either a T3 with a custom trim or go to a bigger sized turbo.

I am actually going to be getting the Sky and make a turbo kit for it so i guess we'll wait and see.

A t28 will be too small in my opinion. I dont care what kind of power rating it gives, it doesnt tell the whole story. I know a guy who has one on his celicawith only a 1.8 motor. Yes, it sure does spool real early, at 2k. Yet at 6k, it flattens out...It doesnt supply enough air. the revs go to 7 k, so it is frustrating. Now he is only running about 8 psi putting around 220hp to the ground, or about 240hp to the crank. Even though the turbo can give more, it still poops out at the high end! Furthermore, I have the same motor in my car. His oil breaks down faster, and he must change it more often. This is because his turbo gets hotter.
The solstice has a 2.4 ..it will even be worse. It will need a bigger turbo imo.
Even with the motor being 10.5:1 CR, you will only be wanting to boost it aroung 7 psi. That will be around 90hp extra , but still , the bigger turbo will pull hard all the way to red line, and run cooler.

 

[stonebreaker]

A t28 will be too small in my opinion. I dont care what kind of power rating it gives, it doesnt tell the whole story. I know a guy who has one on his celicawith only a 1.8 motor. Yes, it sure does spool real early, at 2k. Yet at 6k, it flattens out...It doesnt supply enough air. the revs go to 7 k, so it is frustrating. Now he is only running about 8 psi putting around 220hp to the ground, or about 240hp to the crank. Even though the turbo can give more, it still poops out at the high end! Furthermore, I have the same motor in my car. His oil breaks down faster, and he must change it more often. This is because his turbo gets hotter.
The solstice has a 2.4 ..it will even be worse. It will need a bigger turbo imo.
Even with the motor being 10.5:1 CR, you will only be wanting to boost it aroung 7 psi. That will be around 90hp extra , but still , the bigger turbo will pull hard all the way to red line, and run cooler.

Your buddy's turbo isn't too small, his A/R ratio is too small. It makes for good boost early in the rpm band, but is too restrictive at high rpm. It's always a trade-off - early boost or more horsepower. He should be able to buy a new exhaust scroll that can improve his peak hp with a slight reduction in low rpm performance.

 

[faultline]

Your buddy's turbo isn't too small, his A/R ratio is too small. It makes for good boost early in the rpm band, but is too restrictive at high rpm. It's always a trade-off - early boost or more horsepower. He should be able to buy a new exhaust scroll that can improve his peak hp with a slight reduction in low rpm performance.

yeah, I guess so. I suppose the real art is getting the impeller and turbine sizes to be where you want them.
I still say that if the comressor housing is larger, and the exit nozzle is larger in diameter, you will have cooler temps for the same amount of cfm of air.
I mean, everyone can do what they want. I just dont want anyone to regret getting a smaller turbo, then regretting it.
When you want to make the solstice go, you will be shiftiing and driving between the 4-6k rev range. Do you really want to have the boost at 2k, but flatten out at 6k? ..I doubt it. Why not have boost come on between 3-4k and pull hard till the end. Even if you can get the AR ratio to that effect in a t28 ..it will still be creating more heat than a bigger turbo.
Also, The trick for making good power is to getting as much air through the motor as possible. manifold pressure is simply the resistance of air going through the motor. Big turbos have the umph to knock that air through the motor , like a big baseball bat knocks a ball further, easier than a small bat.
It remains to be seen, but because the ecotec makes good torque down low, I suspect that a big turbo will spool up fairly early on anyway . A t3/4 or the new gt35 would be my choice in my thinking anyway... Like a AR 70 compressor housing...Its a 2.4 motor

 

[stonebreaker]

yeah, I guess so. I suppose the real art is getting the impeller and turbine sizes to be where you want them.
I still say that if the comressor housing is larger, and the exit nozzle is larger in diameter, you will have cooler temps for the same amount of cfm of air.
I mean, everyone can do what they want. I just dont want anyone to regret getting a smaller turbo, then regretting it.
When you want to make the solstice go, you will be shiftiing and driving between the 4-6k rev range. Do you really want to have the boost at 2k, but flatten out at 6k? ..I doubt it. Why not have boost come on between 3-4k and pull hard till the end. Even if you can get the AR ratio to that effect in a t28 ..it will still be creating more heat than a bigger turbo.
Also, The trick for making good power is to getting as much air through the motor as possible. manifold pressure is simply the resistance of air going through the motor. Big turbos have the umph to knock that air through the motor , like a big baseball bat knocks a ball further, easier than a small bat.
It remains to be seen, but because the ecotec makes good torque down low, I suspect that a big turbo will spool up fairly early on anyway . A t3/4 or the new gt35 would be my choice in my thinking anyway... Like a AR 70 compressor housing...Its a 2.4 motor

Well, there's certainly an art to getting the tuning right, I agree 100% with you there.

I don't think a smaller compressor wheel necessarily generates more heat than a larger wheel when moving the same amount of air. If you look at a compressor map like these:

You can see that a given compressor is most efficient when flowing a certain amount of air within a certain pressure range. So the goal is to size the compressor such that it is moving the most efficient amount of air at its most efficient pressure.

Here's a nice turbo sizing primer: http://www.hotrod.com/techarticles/engine/113_0312_turbo/index.html

 

[faultline]

The article you linked to was really good. It is true that you will have the coolest air when the compressor is working at its maximum effeciencey, and the maps show you that. I admit that everything I said was anecdotal. I did say bigger compressor housing, not wheel. But even the t3 50ar trim map you show has a large range that the compressor is working at maximum 75% efficiency. Furthermore the article stated that when selecting your turbo, remember that the larger displacement motor will swallow more air and show lower psi on the boost guage, flowing the same cfm from the compressor no matter what size motor drives it. If that is true, then it would stand to reason that you could flow more air thru the the same motor, with the same turbo at the same psi by changing the wheel sizes of the turbine and impeller. Just because of back pressure created by the turbine, or the extra heat/coolnes by different impeller sizes...and ...and... Even the article stated "Unfortanetly there is now easy scientific method for selecting the ar ratio. Seat of pants feel is important."
Another thing in the article. Did you notice the CR ratio for the motor? 8:1.Is recomendations were for 10psi for non intercooled and a full 1 bar for intercooled for most street applications. But for the high CR for the solstice, you will need an IC for lower boost. The HP per psi will be higher, making the climb for each psi very agressive. An ic will be real important.

 

[stonebreaker]

The article you linked to was really good. It is true that you will have the coolest air when the compressor is working at its maximum effeciencey, and the maps show you that. I admit that everything I said was anecdotal. I did say bigger compressor housing, not wheel. But even the t3 50ar trim map you show has a large range that the compressor is working at maximum 75% efficiency. Furthermore the article stated that when selecting your turbo, remember that the larger displacement motor will swallow more air and show lower psi on the boost guage, flowing the same cfm from the compressor no matter what size motor drives it. If that is true, then it would stand to reason that you could flow more air thru the the same motor, with the same turbo at the same psi by changing the wheel sizes of the turbine and impeller. Just because of back pressure created by the turbine, or the extra heat/coolnes by different impeller sizes...and ...and... Even the article stated "Unfortanetly there is now easy scientific method for selecting the ar ratio. Seat of pants feel is important."
Another thing in the article. Did you notice the CR ratio for the motor? 8:1.Is recomendations were for 10psi for non intercooled and a full 1 bar for intercooled for most street applications. But for the high CR for the solstice, you will need an IC for lower boost. The HP per psi will be higher, making the climb for each psi very agressive. An ic will be real important.

You're right. I wasn't endorsing a particular size of turbo. My only point was that a bigger compressor wasn't always more efficient.

Glad you found the article informative.

 

[slowandlow]

i have a queston will you need to upgrade the stock oiling system to suport a turbo? and i like turbos i get to drive a twin turbo stealth all the time.

 

[stonebreaker]

Turbo Sizing Software
Something to help you pick the best turbo. Just found it myself.

 

[faultline]

i have a queston will you need to upgrade the stock oiling system to suport a turbo? and i like turbos i get to drive a twin turbo stealth all the time.

you need to run an oil line from the motor to the turbo to the oil pan. There is enough oil pressure for the motor's oil pump to do this. When oil goes through the turbo,it gets churned up like whip cream -all frothy like. The line from the turbo to the oil pan needs to be wider in diameter than the line going from the motor to the turbo. .
I think that it would be safe to say that boosting up to 15 psi you would not need to get a larger oil cooler, or a bigger radiator for the motor either.
Becuase the compression is so high in this motor, I cant see anyone boosting over 10 psi on a regular basis. probably more like 7.5 looking for 50% more power out of the motor. Sure you could rebuild the motor for higher boost, but then you are talking about a lot of work, and a lot of $$$.

 

[brentil]

i have a queston will you need to upgrade the stock oiling system to suport a turbo? and i like turbos i get to drive a twin turbo stealth all the time.

The 2.4L engine has the under piston oil squirters and the oil cooler from the 2.0L Supercharged engine I believe. So the engine is already able to take even more heat then the system would already be putting out. It would be great if the oil pan already had the connection point for an oil line for a Turbocharger/Supercharger. Especially a GM official addon.

 

[stonebreaker]

The 2.4L engine has the under piston oil squirters and the oil cooler from the 2.0L Supercharged engine I believe. So the engine is already able to take even more heat then the system would already be putting out. It would be great if the oil pan already had the connection point for an oil line for a Turbocharger/Supercharger. Especially a GM official addon.

Does the Eaton use engine oil? Seems like that would heat things up unnecessarily.

 

[brentil]

Does the Eaton use engine oil? Seems like that would heat things up unnecessarily.

You're right, I forgot most Eatons are self lubricating. But a lot of your Turbocharger or Supercharger setups require you to tap the oil pan to run an oil line for the *charger. I know for sure most Turbochargers require the oil line, which is why you find most Turbocharged cars with oil coolers too.