Well hell I do not know what happened to the post I made last night. Figures as as I took some time on it as well.
Junior,
The point on the 4288 is most that are using compounds on the street want the fast spool up and are not looking at boosting over 100 psi total at the manifold. That puts most turbos comp sides in the 62-67mm size 38r, H2e, QSSB, etc.. The GT4288 has basically a 38r/small 40 compressor wheel but with a Full gt42 center section and turbine wheel. The 42 in the name gives use the center section and usually know turbine wheel and the 88 is the exducer size of the comp wheel This is how Garrett naming convention works.
Yes with your current 4202 you could swap out the comp cover and wheel for the smaller one to get faster spool up and have the same as the gt4288. You could also as a single swap out to the 4294 parts and have that.
With the larger turbine wheel and running a 1.01 housing you will have spool up very close to the a 38R. I and other can say how fast the 4294 with 1.15 spool up. This will be even faster with just the smaller comp wheel but then adding in the 1.01 housing should increase that even more. There maybe smaller housing as well from other companies such as precision.
Then for the atmosphere side there are a number of motors Cats running 4708 and a bunch running 4702s These get you the 92.7mm Turbine wheel and as OTR pull offs most will come with the larger T6 1.39 housing would be my guess. The 4702 has a bit smaller comp wheel @ 102mm instead of 108mm. But that could easily be swapped if needed or more can be put on the manifold as it has plenty of room in the map for it.
The point is both are home rebuildable, can be found as pull offs in salvage yards, can be upgraded and wheels swapped.
You can make changes once you see how they perform and how it matches with your goals and expectations. The make appropriate changes as needed to meet those goals.
As they are salvage yard pull offs it would certainly make a a budget friendly setup. Even if you had to pickup new comp wheels and rebuild kits.
Anyways that was the setup I came up with thinking about it one night as a decent budget friendly setup using pull offs. It should spool up well and make very good linear power based on what I have learned. Then again I have never built a single compound setup in my life so I could at the same time be wrong. But I think while maybe not being "ideal" like a full custom or having choice of any turbo specs it should work fairly well and when you consider the cost....
Then have the 4288 WG into the intermediate pipe feeding the gt47 and its WG vent to atmosphere or its own downpipe. Have the 47 first stage IC from the stock A:A and the 4288 second stage spray water or IC A:W as the final before hitting the manifold.
Dieselboy,
As I understand it would not matter how much larger your atmosphere turbo was when running a larger manifold turbo like you and Junior have. For the typcial pressures a street driven setup is going to have the effect of the manifold turbo is spool up speed. How fast that initial light up and boost can come on. That's what gives us that best of both worlds. Going to a Gt60 may match up better as far as where both are in their maps (will be at very high pressures) but it will not change the fact that you will still have all the lag you get from the 4202 as it was as a single. The only way to handle this is to make changes that will cause the manifold turbo to spool and lite faster. That means smaller comp wheels, and or tighter turbine housing. In this case I would do both. With the larger turbine wheel you will still be moving a good amount of air and of course will be gating the rest into the atmospheres turbine inlet tube.
Junior,
The point on the 4288 is most that are using compounds on the street want the fast spool up and are not looking at boosting over 100 psi total at the manifold. That puts most turbos comp sides in the 62-67mm size 38r, H2e, QSSB, etc.. The GT4288 has basically a 38r/small 40 compressor wheel but with a Full gt42 center section and turbine wheel. The 42 in the name gives use the center section and usually know turbine wheel and the 88 is the exducer size of the comp wheel This is how Garrett naming convention works.
Yes with your current 4202 you could swap out the comp cover and wheel for the smaller one to get faster spool up and have the same as the gt4288. You could also as a single swap out to the 4294 parts and have that.
With the larger turbine wheel and running a 1.01 housing you will have spool up very close to the a 38R. I and other can say how fast the 4294 with 1.15 spool up. This will be even faster with just the smaller comp wheel but then adding in the 1.01 housing should increase that even more. There maybe smaller housing as well from other companies such as precision.
Then for the atmosphere side there are a number of motors Cats running 4708 and a bunch running 4702s These get you the 92.7mm Turbine wheel and as OTR pull offs most will come with the larger T6 1.39 housing would be my guess. The 4702 has a bit smaller comp wheel @ 102mm instead of 108mm. But that could easily be swapped if needed or more can be put on the manifold as it has plenty of room in the map for it.
The point is both are home rebuildable, can be found as pull offs in salvage yards, can be upgraded and wheels swapped.
You can make changes once you see how they perform and how it matches with your goals and expectations. The make appropriate changes as needed to meet those goals.
As they are salvage yard pull offs it would certainly make a a budget friendly setup. Even if you had to pickup new comp wheels and rebuild kits.
Anyways that was the setup I came up with thinking about it one night as a decent budget friendly setup using pull offs. It should spool up well and make very good linear power based on what I have learned. Then again I have never built a single compound setup in my life so I could at the same time be wrong. But I think while maybe not being "ideal" like a full custom or having choice of any turbo specs it should work fairly well and when you consider the cost....
Then have the 4288 WG into the intermediate pipe feeding the gt47 and its WG vent to atmosphere or its own downpipe. Have the 47 first stage IC from the stock A:A and the 4288 second stage spray water or IC A:W as the final before hitting the manifold.
Dieselboy,
As I understand it would not matter how much larger your atmosphere turbo was when running a larger manifold turbo like you and Junior have. For the typcial pressures a street driven setup is going to have the effect of the manifold turbo is spool up speed. How fast that initial light up and boost can come on. That's what gives us that best of both worlds. Going to a Gt60 may match up better as far as where both are in their maps (will be at very high pressures) but it will not change the fact that you will still have all the lag you get from the 4202 as it was as a single. The only way to handle this is to make changes that will cause the manifold turbo to spool and lite faster. That means smaller comp wheels, and or tighter turbine housing. In this case I would do both. With the larger turbine wheel you will still be moving a good amount of air and of course will be gating the rest into the atmospheres turbine inlet tube.
