UPDATED!!*DYNO NUMBERS* Comparison of Comp Turbo Billet 88mm CT6X-88 & GT91 Garrett!!
08-27-2012, 02:44 PM
#181
I don't agree with your "too big" turbine theory. There are plenty of mid 300cubic inch drag racers running 111mm turbine wheels, with LESS than 1:1 backpressure. They don't spool very good, but they are using a 2step and nitrous out of the hole, so it doesn't matter. It's really about gettIng the proper pressure differential across the turbine wheel. I'll find out tonight how the housing effects this.
08-27-2012, 03:55 PM
#182
yeah too big isnt really what I was after looking at it
just plain inefficient at capturing energy is the truth, and yes there are even low 200cid cars running 100+mm turbines (s500) thats not the point
Even pressure differential does no good if the pressure isnt being used to rotate the turbine and is instead just pressure for no reason, which is what is happening here.
Oddly enough I have even thought a smaller turbine housing might actually be better, as it will move the exhaust toward the turbine at a greater angle to the blades, but that is even unlikely
just plain inefficient at capturing energy is the truth, and yes there are even low 200cid cars running 100+mm turbines (s500) thats not the point
Even pressure differential does no good if the pressure isnt being used to rotate the turbine and is instead just pressure for no reason, which is what is happening here.
Oddly enough I have even thought a smaller turbine housing might actually be better, as it will move the exhaust toward the turbine at a greater angle to the blades, but that is even unlikely
08-27-2012, 04:57 PM
#183
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Ive thought about this too. When people say the turbine wheel is maxed is it the inducer/exducer? I think its the exducer that becomes the restriction on the turbine thats when you move up.
Now with the straight cut wheels I believe these are suppose to be used in divided housings for the best effect since its straight. I was thinking maybe on a true divided manifold where the pulses chase eachother that might create the extra trq to push the turbine wheel.
Now to throw a wrench in this you have the venturi effect which a tapered wheel would achieve to help reduce bp. What comes in must come out kind of deal and a suction is created to pull the gases out. Does it work, sure it does, is it better...we dont know. Unless someone put a straight and then a tapered with bp reading we will never know.
To the OP I think i missed the whole post where on your old turbo you were already running into bp issues. So I think using the same size housing was already a bad move. Lets hope the larger housing wakes the turbo up. The high bp iswhat caused it to max out so early rather than letting the wheel flow.
Now with the straight cut wheels I believe these are suppose to be used in divided housings for the best effect since its straight. I was thinking maybe on a true divided manifold where the pulses chase eachother that might create the extra trq to push the turbine wheel.
Now to throw a wrench in this you have the venturi effect which a tapered wheel would achieve to help reduce bp. What comes in must come out kind of deal and a suction is created to pull the gases out. Does it work, sure it does, is it better...we dont know. Unless someone put a straight and then a tapered with bp reading we will never know.
To the OP I think i missed the whole post where on your old turbo you were already running into bp issues. So I think using the same size housing was already a bad move. Lets hope the larger housing wakes the turbo up. The high bp iswhat caused it to max out so early rather than letting the wheel flow.
Last edited by spoolin turbo; 08-27-2012 at 05:04 PM.
08-28-2012, 02:11 AM
#185
Well, everyone was right, the bigger housing only moved it to 2.5:1
I was seeing 10-11psi manifold pressure and around 25psi backpressure... with the new housing.
I will give them one more shot at putting a bigger wheel in it. If that doesnt work, I have no idea what I'm going to do...
Now to decide what wheel to use........??
I was seeing 10-11psi manifold pressure and around 25psi backpressure... with the new housing.
I will give them one more shot at putting a bigger wheel in it. If that doesnt work, I have no idea what I'm going to do...
Now to decide what wheel to use........?? 
08-28-2012, 07:06 AM
#189
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The bigger wheel isn't going to help much. They need to redesign their turbine wheel. But they don't sell much to big engine guys and the import guys like them. So I don't think they are going to change much.
08-28-2012, 10:02 AM
#190
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That sucks man. The only thing i can hope for is that my little 364 won't create as much bp as your 408. At this point i'm well beyond the refund stage so i'm stuck with it. If it doesn't work, i'm gonna have them re-do it again to some supra friendly specs and sell it!
08-28-2012, 03:40 PM
#196
So I talked to comp... They are going to upgrade the turbo to a ct6x turbo. It has a gt55 size compressor cover, they are going to put a slightly larger compressor wheel, and the bigger gt55 turbine wheel. I'm stepping down to the 1.23 a/r, unless you guys think the 1.08 would work better...
08-28-2012, 03:49 PM
#198
As far as the A/R, from the results I've seen, go with a small A/R and a large turbine wheel (within reason of course). This is also what the mutli-million dollar Formula One cars did back when they were turbo. It seems A/R can kill spool, but not add a ton of power up top.
Post number 150 by Marvin@Tick supports this also.
Post number 150 by Marvin@Tick supports this also.
Last edited by slow67; 08-28-2012 at 03:55 PM.
08-28-2012, 04:08 PM
#199
08-28-2012, 04:24 PM
#200
As far as the A/R, from the results I've seen, go with a small A/R and a large turbine wheel (within reason of course). This is also what the mutli-million dollar Formula One cars did back when they were turbo. It seems A/R can kill spool, but not add a ton of power up top.
Post number 150 by Marvin@Tick supports this also.
Post number 150 by Marvin@Tick supports this also.
LMAO!!! Come on man!!!
But yes I agree 100%, large turbine wheel(within reason) tight ar.
I think if it is truly a GT55 turbine wheel without a straight cut wheel and it's 111mm then it will work well for you. If you can go back with the 1.08 on the larger wheel.