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.

 

Thanks for the info and pics... when is the dyno comparison coming?

 

Yes, thank you. VERY informative.

 

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 just so everyone knows, if you havent seen my other posts, this is a gt4082 (50 trim). it is NOT a gt40r

 

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?

 

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...

 

Pump Gas?

 

Well the Q trim generally flows more doesn't it?

 

always =]

i dont really go past 21-22 psi on pump. im set at 20 right now. quite happy with it

 

Its not regular Q trim afaik. I dont think the difference in flow i that much. its the regular gt-40 turbine.... whatever that is...

 

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.

 

Man i hate the fact that there is so little standard in this industry.

 

im using the hks. works great.

 

I was referring to a compressor.

 

well you said somethin bout the hks manifold, i was just saying that was used in my setup =]

as for the .96 back, go with either a 61 or a 66 depending on the boost you want to run

 

20 psi on pump gas

 

you running 20 psi with some type of injection? water/alcohol?

 

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.

 

I'm even more excited now. Although I'm just getting the GT40, it's going to go in a 1900lb miata, accompained by a 13B of course

 

Aww come on, you can't say that without telling what you run! AFR around 10.5:1 and timing around 10 degrees??? Tell us

 

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

 

afr 11:1, timing 13 degrees at 20 psi, 10 split

 

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.

 

Very good info. This gives me a rough idea of what to expect with the setup im planning on using.