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will this turbo work?


Guest fatones

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Guest fatones

I'm now in the process of installinig my turbo engine into my 72 Z. The donor engine came from a junkyard car. So I took it apart and inspected all the internals. Everything looked good so I put it together with new gaskets and timing chain. The bad part is that the PO had gotten the turbo really hot and shut the engine off without allowing the centersection to cool down. The turbo is now completely useless and I'm going to have to purchase a new one. My plan is to get an upgraded turbo now so I wouldn't have to buy another one later on when I start bolting on all the upgrades. I've been looking at the t4-t3 garrett hybrid with 57 trim and a .63AR housing from Speed Shop Thaggard. I'm sure this turbo would be fine if I had an intercooler to cool down the air. However since I don't have an intercooler for the time being can I use this turbo without worrying about detonation? I'll be running the stock 7 PSI until I'm able to upgrade later on. It would seem with the bigger turbo even though I'm running the stock boost level that more air would be pushed through the engine due to the increased compressor size. Should I be worrying about this or not? Any guidance would be appreciated. Thanks for your time. TIM

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fatones,

 

7 psi coming out of the old stock turbo is the same 7 psi coming out of the newer, larger turbo with one exception....

 

The larger turbo is likely to be more effiecient than the stock turbo (check a compressor map to be sure). The temperature of the compressed air that the new turbo is putting out at 7 psi on the same motor will be cooler than the stocker.

 

The answer is No, more air will not be "pushed into the engine" provided that you are at the same boost level.

 

See some compressor maps here:

http://www.atlanticz.ca/zclub/techtips/turbo/turbomaps/

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Guest fatones

Thanks for all of your replies and advice. I'll go ahead and install the larger turbo and run it at the stock level. Can't wait to get it going. Thanks again TIM

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Guest Cronic
fatones' date='

 

7 psi coming out of the old stock turbo is the same 7 psi coming out of the newer, larger turbo with one exception....

 

The larger turbo is likely to be more effiecient than the stock turbo (check a compressor map to be sure). The temperature of the compressed air that the new turbo is putting out at 7 psi on the same motor will be cooler than the stocker.

 

The answer is No, more air will not be "pushed into the engine" provided that you are at the same boost level.

 

See some compressor maps here:

http://www.atlanticz.ca/zclub/techtips/turbo/turbomaps/[/quote']

 

WOAH WOAH WOAH, that's a false statment there... just wait one minuite. 7psi from a 60 trim t3 is NOT the same as 7psi from a 50 trim t4.

 

For example only, a t3 60trim will put out 200cfm @ 7psi, and a t4 50 trim will be more like 350cfm. This IS more air comming through, it will not be more pressure, BUT WILL make more power. Please do not mistake that.

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Just some friendly discussion of the way I understand it :wink: ...is this correct?

 

The CFM is dependant on the pressure ratio, the motor, and the RPM.

 

For the same L28 at the same RPM at the same boost level, the CFM will be the same regardless of what turbo you are using.

 

The only assumption is that both turbos are capable of maintaining the flow.

 

a t3 60trim will put out 200cfm @ 7psi, and a t4 50 trim will be more like 350cfm

At what RPM? A t3 60 trim will easily flow 200cfm, otherwise they couldn't maintain 7psi above 3250RPM.

 

Please check a compressor map again on the above webpage and I think you'll see what I mean.

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Chronic, I'm sorry to say, you are a bit off on that last post, and Sims is correct.

First, 7psi is 7psi.

 

The CFM you state means the more efficient unit has the POTENTIAL for supplying more CFM at a given PSI.

 

But only if your engine REQUIRES the additional flow.

 

Basically the less efficient turbo more than likely will be turning a faster RPM to make the same Backpressure in the intake manifold.

 

PSI is just a resistance to flow.

 

This is why some cars make 300hp at 10 psi, and others need 15psi to achieve.

 

Don't confuse airflow potential with PSI. The reason the more efficient unit has cooler air is due to operating at a more optimum tip speed. The pressure ratios are the same to get 7psi. Pressure ratio of the wheel only says it's potential.

 

To get 7psi on the same engine, you only need feed it with X CFM, no matter what the turbo is capable of delivering.

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The difference in power made at the same boost level will be due to the density of the air, meaning how much cooler the air is after being compressed. At 7 psi, any stock Z EFI can fuel the increased density - it will just act like the ambient air is 30 degrees lower. :D

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