Kazuya1274 Posted September 23, 2005 Share Posted September 23, 2005 I've had this question pop up in my head. You have 2 engines, a 1.6L and a 5.7L that both put out 300hp. Obviously, the 5.7 is going to last a lot longer (as in more reliability) than the little 1.6 because the 1.6 is working a lot harder to make that 300hp than the 5.7. With that said, lets take an L28. One has the stock T3, and one has a much larger T66 turbo. Let's say both put out 350 hp. The T66 turbo'd engine will have less strain and less heat generated because that large turbo does not have to work as hard to make the target HP. The T3 turbo will have to spin faster and in turn generate more heat to reach that HP. So if more displacement = more reliability (as far as power is concerned), would this apply to turbochargers as well? The T66 turbo can probably make 350 HP a lot easier than the T3, right? Would it be more reliable? Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted September 23, 2005 Share Posted September 23, 2005 yes... Quote Link to comment Share on other sites More sharing options...
johnc Posted September 23, 2005 Share Posted September 23, 2005 I think you're adding 2 + 2 and coming up with 5. A turbo works by transferring energy from the exhaust to energy in the intake. To some degree that process is independent of the engine itself. Let's try this example: Turbo A spins at 20,000 rpm, creates 300 horsepower, and generates X btus of heat in the intake. Turbo B spins at 30,000 rpm, creates 300 horsepower, and generates X * 1.25 btus of heat in the intake. Does that additional 25% heat load in Turbo B's intake reduce the expected longevity of the engine? IMHO, probably not if the mixture is correct, the cooling system works properly, etc. Does that additional 10,000 rpm of turbine speed affect the longevity of Turbo B? IMHO, probably not considering how infrequently a turbo is spinning at max rpms (at least on a street car). But, then again, the above might be a bad example. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted September 24, 2005 Share Posted September 24, 2005 I would think the turbo itself would last longer though, no? I know a T3 is living on borrowed time at really high boost levels, say 15psi or more. The bearing just can't put up with that much boost for long. Yet, 15psi is where a T4 really just starts to wake up, isn't it? or at least, I never hear of anyone expecting a T4 to fail at 15psi. I don't think it matters much to the engine though. Quote Link to comment Share on other sites More sharing options...
Clifton Posted September 25, 2005 Share Posted September 25, 2005 I would think the turbo itself would last longer though' date=' no? [/quote'] I would agree with that. The smaller motor wouldn't nessacarily be less reliable. If It was beat on constantly and saw alot of revs it may have a shorter life. The engine would just be an engine until it came into boost. Corvettes make about twice the power they did in the early smog days. I wouldn't think they are less reliable. To answer your other question. Yes a T66 would make 350hp more reliably. It will make about twice that. The T3 (60 trim) is at the end of it's map and the shaft speed is over 140k rpms with the efficiency way down. The shaft speed is the problem. They will come apart. Quote Link to comment Share on other sites More sharing options...
Drftn280zxt Posted October 7, 2005 Share Posted October 7, 2005 but if I'm not mistaken if you had two cars making 350hp and one had a smaller turbo and the other a larger one. Wouldn't the car with the larger turbo take longer to build boost? Higher engine rpms. Or am I mistaken. I alwats thought, little turbo, spools faster, builds boost early, low rpm. Big turbo, spools slower, builds boost later, high rpm. Fill me in if I'm wrong. You guys are making it sounds like making 15 psi in a little turbo will take longer then when the bigger turbo. For example, little turbo 15psi @3000rpm, big turbo 15psi @2000rpm, that how you guys are making it sound, is that right or wrong? Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 7, 2005 Share Posted October 7, 2005 but if I'm not mistaken if you had two cars making 350hp and one had a smaller turbo and the other a larger one. Wouldn't the car with the larger turbo take longer to build boost? Yes the bigger turbo would have more lag and take longer to build boost. The smaller turbo would require more boost to make 350hp than the larger turbo. If the boost were equal the larger turbo would make more power. Quote Link to comment Share on other sites More sharing options...
Drftn280zxt Posted October 9, 2005 Share Posted October 9, 2005 is that because the bigger turbo is pressurizing a larger volume of air than the small turbo? I guess the reasoning your guys are aiming for is have the turbo spin at lower rpm to create the same amount for greater reliability in the turbo, not necessary the motor, correct? Because one way you have a turbo spinning at high rpm and engine rpm is low, and the other is a low rpm spinning turbo with high rpm spinning engine. So I guess there really is not a win win situation unless you can find a combo that offers a turbo that spools at moderate rpm while engine rpm is moderate, say like 4k rpm (engine) rather than big turbo at 5k+ engine rpm. Is this what you are aiming to explain. Of course I guess you could build the engine to "live" at high rpm so that you could a large "slow" spinning turbo. Plus if it is spinning slower temperatures wouldn't be as extreme as they are in the smaller high rpm turbo, correct? But I don't think many people by a bigger turbo for more reliability, they buy them to run more boost at probably the same or higher rpm (turbo rpm) as the small turbo was running. Very interesting thought though Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 9, 2005 Share Posted October 9, 2005 A large wheel cannot handle the speeds a smaller wheel can and doesn't run at the same speeds. Kinda like diesel motors. If you compare a T3 60 trim (stock 280ZX turbo) and a T4 with a 62-1 compressor wheel. They will both make 300 hp. The T3 wheel is about at the end of the map and the efficiency is lower, making more heat, requiring more boost to make the same power. The T3 turbine wheel is also alot smaller than a T4 wheel or upgraded T3 wheel. While it will spool faster it will not flow nearly as much or have the torque to turn a large compressor wheel. If run with a large compressor wheel it will have more backpressure to make the same boost. You have to compare both the compressor and turbine side. Yes some on this board run T3/4's with stock turbine wheels. They also don't make the power they could be making. Hopefully these come up. 16 psi intercooled is about a 2.2 PR. Close to the safe limit on pump gas. It is enough to make 350 rwhp/400hp+ crank (yes not everyone makes that but again most use a T3 turbine wheel). 10lbs/min is about 10 hp. You can see the T3 compressor is way off the map. It is living on barrowed time. The other 2 are still good. If you wanted to run more octane and 23 psi the T4 E60 would be to small too. The 62-1 would work though. Quote Link to comment Share on other sites More sharing options...
Drftn280zxt Posted October 11, 2005 Share Posted October 11, 2005 A large wheel cannot handle the speeds a smaller wheel can and doesn't run at the same speeds. Kinda like diesel motors. If you compare a T3 60 trim (stock 280ZX turbo) and a T4 with a 62-1 compressor wheel. They will both make 300 hp. The T3 wheel is about at the end of the map and the efficiency is lower' date=' making more heat, requiring more boost to make the same power. The T3 turbine wheel is also alot smaller than a T4 wheel or upgraded T3 wheel. While it will spool faster it will not flow nearly as much or have the torque to turn a large compressor wheel. If run with a large compressor wheel it will have more backpressure to make the same boost. You have to compare both the compressor and turbine side. Yes some on this board run T3/4's with stock turbine wheels. They also don't make the power they could be making. Hopefully these come up. 16 psi intercooled is about a 2.2 PR. Close to the safe limit on pump gas. It is enough to make 350 rwhp/400hp+ crank (yes not everyone makes that but again most use a T3 turbine wheel). 10lbs/min is about 10 hp. You can see the T3 compressor is way off the map. It is living on barrowed time. The other 2 are still good. If you wanted to run more octane and 23 psi the T4 E60 would be to small too. The 62-1 would work though. [img']http://not2fast.wryday.com/turbo/maps/t3-60.gif[/img] What do you mean "way off the map" I'm kinda confused with the meaning of the map in the first place Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted October 11, 2005 Share Posted October 11, 2005 My $0.02: An engines reliability is determined by ensuring no detonation and not revving it beyond what its built for. A turbos reliability depends on a couple of things, ensuring that the pressure in the turbine housing isn't too high that it blows seals (this is affected by the amount of air you are trying to pass through it relative to the cam/head/exhaust manifold/exhaust), and not spinning it beyond what its designed to do. I have also heard that turbos with restrictors tend to blow seals because the turbine is sucking so hard it creates a vacuum between restrictor and compressor and effectively pulls the shaft towards the restrictor. Can't think of anything else atm. Dave Quote Link to comment Share on other sites More sharing options...
Dave88SS Posted October 11, 2005 Share Posted October 11, 2005 10lbs/min is about 10 hp. You can see the T3 compressor is way off the map. It is living on barrowed time. The other 2 are still good. I think you mean 10lbs/min ~ 100hp? Try reading the maps now Drftn, hp/10 on the X axis and PR on the Y Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 11, 2005 Share Posted October 11, 2005 I think you mean 10lbs/min ~ 100hp? Try reading the maps now Drftn' date=' hp/10 on the X axis and PR on the Y [/quote'] Oops, your right:redface:. What do you mean "way off the map" I'm kinda confused with the meaning of the map in the first place Look at the T3 map and see where 35 lbs/min is. It is off the right of the map. The turbo could do it but it is not design to run there. The efficiency will be way down as reliablilty. The turbo needs to be matched to the power output. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted October 11, 2005 Share Posted October 11, 2005 what about the increase thrust load on the bigger compressor wheel on small shaft t3 turbine wheel? That'll make the larger turbo not as much reliable. Quote Link to comment Share on other sites More sharing options...
Chris240zTurbo Posted October 12, 2005 Share Posted October 12, 2005 Hey Clifton, not to get too far off the subject, but would you like to take a wild guess (roughly) what power I'll put down with a T-04S, 60-1 comp. and .58 P-trim (on center) turbine? 23 psi boost... I'm thinking of going to the dyno tomorrow, if they don't have it booked, and make a few pulls, if I remember correctly, don't you also run a 60-1 on your L28 car? Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 12, 2005 Share Posted October 12, 2005 I did run a V trim compresor. At 22 psi I did 417rwhp. If your afr is in the high 11's/ real low 12's with timing in the low 20*'s. As long as you're not running a Conquest intercooler, I don't see why you wouldn't do atleast that if not more. Do you have the injectors and octane for 23 psi? Quote Link to comment Share on other sites More sharing options...
Chris240zTurbo Posted October 12, 2005 Share Posted October 12, 2005 thats about what I thought, I run a spearco 221 core, 18.5x8x3.5, 1080cfm, and 550cc injectors, datalogs show 89% duty cycle at 23psi and 7K rpm, so thats all in order, timing is set for 24* @23 psi, and texas pump gas is 93 oct, the only thing concerning me is the AFR, I have it tuned to about 11:1 under full boost (LM-1 wideband kit) it has been running like this for several months now, although I don't drive the car daily anymore, maybe 2K miles on the new setup. Anyway, I hope to make some time tomorrow to go find out! Thanks, Chris Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 12, 2005 Share Posted October 12, 2005 I would lean it out to around 11.7-11.8. It's still plenty safe and you will pick up quite a bit of power running that kind of boost. Quote Link to comment Share on other sites More sharing options...
Drftn280zxt Posted October 14, 2005 Share Posted October 14, 2005 Oops' date=' your right:redface:. Look at the T3 map and see where 35 lbs/min is. It is off the right of the map. The turbo could do it but it is not design to run there. The efficiency will be way down as reliablilty. The turbo needs to be matched to the power output.[/quote'] Uh, how are you figuring that it is right off the map? If I draw a vertical line coming up from 35 there is all kinds of values. Is this a contour map? I'm still a lost please be patient, I want to learn, but I'm lost. Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 14, 2005 Share Posted October 14, 2005 Uh, how are you figuring that it is right off the map? If I draw a vertical line coming up from 35 there is all kinds of values. Is this a contour map? I'm still a lost please be patient, I want to learn, but I'm lost. Where 2.2 (PR) from the left intersects with 35 lbs/min. Of corse full boost isn't made at idle and flow is a product of boost and rpm. If 35 lbs was used at 6K rpm then 17lbs /min would be around 3200 rpm. The PR would be the same 2.2, as a small turbo like that would easily make full boost by then. So the line would curve up from a 1.0 PR and start around 5 lbs/min. Curving up torwards 2.2-17lbs and level off to 2.2-35 lbs . Quote Link to comment Share on other sites More sharing options...
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