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Turbine sizing - CM2 to A/R


Boosted_One
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Personally I wouldn't go much further than .70 unless it was on NOS and a drag car.

 

.63 - .70 in a good flowing turbine is a big increase... you can't take those numbers at total face value. A T3 or T4 .58 A/R will simply outflow an 8cm2 05 housing because the inlet and outlets are larger.

 

So it isn't exactly cut and dry...there's a few variables there that throw a direct comparison out the window.

 

Good example is the 06-17C Ty/Sy turbo..it has the same 8cm2 housing as us but a larger turbine inlet and outlet so it will flow better than the same 8cm2 05 housing.

 

You can go bigger on the hotside but it will really take some time to build pressure. That's  where displacement comes into play and why a V8 can spool a 1.18 A/R no problem.

 

I've been in cars with large turbine A/R and man for seemingly days the turbo would just lag and pause...hard to get thru a yellow light!

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  • 3 weeks later...

Its always a catch 22. Small A/R and your turbo spools quickly and your on the boost fast at low rpm. The catch is at high rpm it gets in the way of the exhaust and causes back pressure limiting HP.

Large A/R your turbo spools slower and the boost comes in later. This allows less back pressure and more HP at the same boost. The catch is mid range boost will suffer and your cars response will be slow.

You have to find a happy medium. With a selection of compressors you can have a bigger compressor with a large A/R turbine and you can save the mid range. The catch is some big compessors have slower max speeds and are more efficient at lower pressure ratios. Others are better at higher pressure, but need more speed so they cause more back pressure before the waste gate opens. The only way to get the exact combo for you and your mods is to copy what someone else has put time and money into researching or put the time and money into researching it yourself. Its all guess work unless you can try something and confirm on a dyno.

You can get in trouble and way off course if you try bolting on a huge turbo without a bigger exhaust and larger intake plumbing. On the other hand if you build it this way dont expect it to be any good as a street car or autocross.  

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So it isn't exactly cut and dry...there's a few variables there that throw a direct comparison out the window.

 

Good example is the 06-17C Ty/Sy turbo..it has the same 8cm2 housing as us but a larger turbine inlet and outlet so it will flow better than the same 8cm2 05 housing.

 

Yup.  I'm upgrading my 20g to a 06 hot wheel and putting a sy/ty turbine housing on it.  Its inlet is a lot bigger than the factory housing.  Here are some pics.  You can see the sy/ty 8cm has a bigger cross section all the way to the turbine and the stock 8cm necks down a lot faster.  Faster spool but definately a bottle neck.

 

ADAM

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Yup.  I'm upgrading my 20g to a 06 hot wheel and putting a sy/ty turbine housing on it.  Its inlet is a lot bigger than the factory housing.  Here are some pics.  You can see the sy/ty 8cm has a bigger cross section all the way to the turbine and the stock 8cm necks down a lot faster.  Faster spool but definately a bottle neck.

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ADAM

 

 

THANK YOU! For posting the comparisons.

 

If you could please make a new thread in the advanced mechanic forum with those pics and I will transfer that over to the FAQ area as 05 and 06 comparisons.

 

You are so doing it right running that 06 housing. For real kudos to you!! I want to know how *well* (and it WILL) it performs! !  ;D

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Yup.  I'm upgrading my 20g to a 06 hot wheel and putting a sy/ty turbine housing on it.  Its inlet is a lot bigger than the factory housing.  Here are some pics.  You can see the sy/ty 8cm has a bigger cross section all the way to the turbine and the stock 8cm necks down a lot faster.  Faster spool but definately a bottle neck.

 

ADAM

 

Looks good you will notice a massive increase in top end  ;) I guess my Ralliart TD06-19C is maybe a 10cm2. It does not have a size written on it.

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Looks good you will notice a massive increase in top end  ;) I guess my Ralliart TD06-19C is maybe a 10cm2. It does not have a size written on it.

 

 

Hey MrB!

 

Does your ralliart turbine inlet flange look like that?

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