PT61 VS GT-40 (my comparison)
11-19-04, 11:06 PM
#1
PT61 VS GT-40 (my comparison)
well, i just went from my gt-40 to a PT61. .96 undivided on both so this will be a pretty even comparison even though both of them use a different exhaust turbine.
Boost response:
Even until 10psi. (both turbos in 4th gear make 10psi@4000rpm)
PT61: 20psi@4500rpm
GT40: 20psi@5000rpm
Boost:
GT40 Would trail off boost up top. If i started at 20psi, id end at 15-16 once i hit 7000rpm.
GT40 would NOT build full boost in first/second gear
PT61 shows 20psi in first and second gear.
Power:
At the same boost leve, they make almost exactly the same power.
The PT61 was able to flow more air up top and keep the pressure up
The GT40 was not.
Physically the PT61 is smaller, but the compressor wheel is 2mm bigger on the inducer side.
The GT40 has more of that neat high pitched turbo whine than the PT61, the PT61 you hear more air flow than anything.
Boost response:
Even until 10psi. (both turbos in 4th gear make 10psi@4000rpm)
PT61: 20psi@4500rpm
GT40: 20psi@5000rpm
Boost:
GT40 Would trail off boost up top. If i started at 20psi, id end at 15-16 once i hit 7000rpm.
GT40 would NOT build full boost in first/second gear
PT61 shows 20psi in first and second gear.
Power:
At the same boost leve, they make almost exactly the same power.
The PT61 was able to flow more air up top and keep the pressure up
The GT40 was not.
Physically the PT61 is smaller, but the compressor wheel is 2mm bigger on the inducer side.
The GT40 has more of that neat high pitched turbo whine than the PT61, the PT61 you hear more air flow than anything.
11-19-04, 11:59 PM
#4
dyno soon. I should make about 475rwhp with this turbo simply from the extra boost, as they both flow about the same amount of air. i didnt have to retune my maps except in the areas i couldnt reach before (not enough boost).
Also, with the pt61 my car runs much cooler. I think the gt41 might have been heating my oil excessively for some reason.. very strange.
Also, with the pt61 my car runs much cooler. I think the gt41 might have been heating my oil excessively for some reason.. very strange.
11-20-04, 12:13 AM
#6
W. TX chirpin Monkey
Join Date: Sep 2001
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So to recap. The turbine section was an undivided .96 A/R, and P-Trim for both wheels? The only difference in the two, was the Compressor housing and wheel. Am I on track?
11-20-04, 12:14 AM
#7
the turbine was a p-trim on the pt61, the gt-40 i think was a GTQ turbine.
you can see they're different in the pics, heres a pic of the gt-40 turbine
its actually bigger than the p-trim blade but the fins arent as straight at the end...
you can see they're different in the pics, heres a pic of the gt-40 turbine
its actually bigger than the p-trim blade but the fins arent as straight at the end...
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11-20-04, 12:21 AM
#12
W. TX chirpin Monkey
Join Date: Sep 2001
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I have an Extrude Honed Ceramic Coated undevided .96 Turbine housing that i'm debating what to mate it up with? 4 bolt pattern for TO4 flange. aka HKS manifold.
11-20-04, 12:30 AM
#16
Originally Posted by fastrotaries
I was referring to a compressor.
as for the .96 back, go with either a 61 or a 66 depending on the boost you want to run
11-20-04, 01:20 AM
#19
Originally Posted by Rx_treme
you running 20 psi with some type of injection? water/alcohol?
good a/f ratio and timing is very important.
11-20-04, 10:09 AM
#21
Weird Cat Man
Originally Posted by nyt
nope. dunno why everyone thinks 20psi is high up there.. ive run 22 on stock motors with 93 octane ... no issues... i keep it at 20 incase i get some shitty gas or something...
good a/f ratio and timing is very important.
good a/f ratio and timing is very important.
11-20-04, 10:20 AM
#22
Mad Man
can someone put the same lines on this T.netics T66 map? Also why are ther only compressor maos? It seems ther should be turbine maps, and then some sort of compilation, that shows you the combo. Is such oftware readily available, i am pretyy sure the maps are not readily available. the Turbine map would show you shaft speed based on the engines exhaust flow, the shaft speed would then give you a point on the compressor map. at that point, you could see what various turbine/compressor combo would be righht for your motor. Carl
11-20-04, 12:01 PM
#24
blue lines represent 55lbs/min and 27 lbs/min @ 20 psi
red lines are 30 psi @ 70lbs/min
as you can see this turbo is a little big if youre just going to be running 20psi.. its more suited for race applications where the boost/airflow is way up there.
