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So i currently have a mp T70 on the car with a .68 housingThe car is an animal but feels like it is choking up around 5400rpms. What differences will i see if i go to a .81 or a .96 housing on my t70??? i understand spool up will be longer as now there really is none, boost is pretty instant.ibaught a .81 housing but for some reason i really think i should have gone with the .96. any insight from someone who has done this swap would be great!!

:salute:
 

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I'm really new to this stuff but I have a on3 351w kit on the way and it comes with a .96 and 3.5" down. The 302 kit comes with a .68 and a 3" don't know if thats any helpfull info to you....
 

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So i currently have a mp T70 on the car with a .68 housingThe car is an animal but feels like it is choking up around 5400rpms. What differences will i see if i go to a .81 or a .96 housing on my t70??? i understand spool up will be longer as now there really is none, boost is pretty instant.ibaught a .81 housing but for some reason i really think i should have gone with the .96. any insight from someone who has done this swap would be great!!

:salute:
How big is your downpipe, if only 3" it will choke you up top. What kind of power you are making? after 630 .68 housing was choking my car bad so I change it to .96 and open downpipe and made 687rwhp and 677 torque but my valve springs floated. Now I have high load comp cams valve springs 120lb seat pressure I should be easy 700+rwhp.

Few things you want to look
Downpipe size, 4" will open up any back pressure
Valve springs
.81 housing should do you good

.68 spools fast, I was getting 8 psi by 2800 rpm and by 3500 I get 20 psi, now with .96 housing I get little lag and get 20 psi by 4k.
 

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3" downpipe is good for about 700 bhp. The .81 will be good, the instant spool is fun for the street but u can only apply so much pedal before the tires give. The bigger housing will allow more power to the ground before the tires give. Hell my t4 choked my topend so I just upgraded to a t6:eeek:
 

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3" downpipe is good for about 800hp. The .81 will be good, the instant spool is fun for the street but u can only apply so much pedal before the tires give. The bigger housing will allow more power to the ground before the tires give. Hell my t4 choked my topend so I just upgraded to a t6:eeek:
Whats the motor combo?
 

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3" downpipe is good for about 800hp. :
I don't think so, have seen little over 700 with 3" downpipe and power falls off right around 6k rpm. in twin turbo yes but not with single turbo unless it's 4cl :rofl:
 

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Reread that section of Max. Boost and the graph shows a little over 700bhp. My bad...post edited.


My setup was a TP38 @12lbs (off a Powerstroke), 302, T5, H/C/I and 3.90 gears....just the regular bolt ons, u know :rolleyes:
 

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Jersey True Street Guy
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So i currently have a mp T70 on the car with a .68 housingThe car is an animal but feels like it is choking up around 5400rpms. What differences will i see if i go to a .81 or a .96 housing on my t70??? i understand spool up will be longer as now there really is none, boost is pretty instant.ibaught a .81 housing but for some reason i really think i should have gone with the .96. any insight from someone who has done this swap would be great!!

:salute:
There are a lot of variables involved here, on that setup you may actually see the best result on the .96 housing if you race the car. It may seem a tad counter intuitive, but a super fast boost ramp doesn't necessarily make a car easier to drive at the track or on the street. Having a "slight" amount of lag helps you get the car out of the hole, and what you may make up at higher rpms may actually make the car go faster.

Exhaust volume/velocity has too many variables for simple math. There are some guys on the turbo forums who are propeller-headed enough to actually calculate it.

The other problem, is too small a turbo, or a very constrained turbine housing can actually cause you to create a lot of backpressure and damage the turbo. I'm not sure why they ship those with a .68 housing, seems smaller then what most people are using. Is your wastegate opening when you are feeling that flattening at 5400? Backpressure will force a wastegate open even if the car isn't at target boost. If you keep trying to outsmart it you will lose, your motor will win, and you will be buying a new turbo.

Are those housings too expensive to buy both and test the *^&% out of it? They are actually easy enough where you could swap them at the track if you have enough cool down time. We would all have a good time reading about it!
 

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Discussion Starter #12
THanks for all the good feedback guys i just decided to keepbthe 81 and order the 96 as well im going to try both. Honestly i have a feeling im going to stick with the 96.
 

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I have a pretty close to stock motor with a mp T70 with a .96 A/R and I see full boost at 3000rpms. It made 452 at 8psi on a hot day
 

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you should check the exhaust pressure and see if its getting to high. That will tell you if you need a bigger ar.
 

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I would like to know what size exhaust hosing on3 offer on the 70mm kit?
 

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Discussion Starter #16
Whatever one you want thats where im ordering mine from
 

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Discussion Starter #18
I honestly have no idea.
 

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I don't think so, have seen little over 700 with 3" downpipe and power falls off right around 6k rpm. in twin turbo yes but not with single turbo unless it's 4cl :rofl:
I'm making 787RWHP @ 15psi which is about 900fwhp through a single 3"DP with full exhaust including tailpipes. This is on a 352ci motor that sees 7500rpm. Is it the best setup? No. Would a larger DP help? I'm sure it would. But don't count out a 3"DP. My backpressure is about 2:1 FWIW on a GTS 76mm with a .96 housing with a T4 flange.
 

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