.. between the hks t04r and t04r cutback:



this is a key so you can tell what the numbers are:



Turbo Output, Compressor Wheel, Compressor Housing, Turbine Wheel, Exhaust Housing:



PS, Trim Inducer (mm), Major (mm), Inlet (mm), Outlet (mm), A/R Trim Major (mm) Exducer (mm) Inlet Flange Oulet Flange A/R



first :

T04R 650ps, 63, 66.7, 84, 100, 60, 0.7, 76, 74.2, 64.7, T04 Flange - 1 Port Insert Type - 65.75 mm 0.81

T04 Flange - 1 Port 0.96

T04 Flange - 2 Port 1.15



second (cutback):

T04R Cutback 700ps, 63, 66.7, 84, 100, 60, 0.7, 76, 74.2, 64.7, T04 Flange - 1 Port Insert Type - 65.75 mm 0.81



is the t04r design to spoolup faster (i think no, just designed for more hp at top end, but it has a smaller a/r compared to the bigger .96 and 1.15 that you can get)? i'm confused, is there a write up that explains all this stuff?



and if anyone knows how does the t04r compare to the t78 (not about lag but top end power)?

and is the t78 based on a t04 (manifold)?



luigi

the T04Rs are made for beefy and broad power band. Most of the Garrett turbos are designed to have good efficiency around the 1 bar range, plus minus...

According to Mr. Kuruyama (HKS turbo development) the HKS has good high end as well, but they made the turbo with reducing exhaust restriction in mind. It has some lag, but not terrible at all.

The T78 from Greddy (Mitsubishi hybrid style) is not based on T04 design. the flange is more square, and the manifold is longer runner, stainless steel tubular design. The HKS turbo sits close and lower then the T78, it is also bigger physical size, thats why it has to be located higher and forward.

I think the T78 has slight more flow on the top end... It is a higher flow turbo, and generate more cfm. But the T78 is very peaky, slightly laggy. Not a bad choice turbo for drag race, a lot of people have good success with the T78, such as Vosko and Ari ...

The T04Rs on the other hand can be a great choic for road race application. The very efficient and broad power band has a lot of advantage on the race track. Peter Farrell uses a T04S turbo (also Garrett) and similar A/R ratio, and have good success in road racing.

wow your good thanx.



luigi

you are welcome. https://www.nopistons.com/forums/pub...#>/biggrin.png

i dunno my T78 isn't laggy and it's not peaky past 6k rpm you def get a kick in the pants. i have been in works2r's car it is very fast but its alot smoother than my T78 as for the original question i think the T04R cutback has a clipped exhaust wheel ? maybe ? i am guessing lol

is work in nj or ny? and by smoother, what do you mean? how is his top end versus yours?



luigi

yep, the cut back version has a clipped ex wheel to increase top end flow... Also Mitsubishi turbo's are actually better at and around the 15psi area and most garrett turbos are made to actually flow higher up... The T04R isn't really comming on line till 18 psi. Some of the larger garret turbo's aren't good till you push them up in to the 22psi + area.

so is this why it may appear smoother, because it comes on later (as far as power is concerned).



luigi

Yep, a smaller turbo or a turbo designed for lower boost aplication will spike faster creating a big jump in the power band all at once. This can be like dumping the cluth all over again and cause wheel spin and cause you to be slower than a turbo that will transition in the power a little slower and help you maintain traction and then give you a much higher top end power as well so it doesn't fall off at the end of 3rd and 4th gear.