opinions needed: turbo size

[wakebum2507]

so while i'm auto swapping, i'm considering going to a T5 or T6, and ditching the 7675. I made great power with it, but I think the exhaust wheel is restricting the top end, which i'll want to utilize with the auto.

i know some of you with custom kits, and CPR kits run borg turbos, in a t6.

thoughts on something like an 80/87, or 76/87, with a 1.10AR T6?

with the larger exhaust wheel, it should shift the power to later in the RPM, and as long as i don't drop below 5300ish on the shifts, it should still stay in the torque, and have a more linear HP curve, where as my 7675 doesn't climb too much on the HP side after about 6000.

anyone with experience, please knowledge bomb me.

will also probably be going to a ported head, ported intake and TB, so that should help flow a little.

 

[Aaron@JPCRacing]

It's a tough on for sure. If you want a really good spool time the 7675 is really nice. The issue with the 6R80 is you cant lug to motor down enough to really take advantage of the bigger turbo.

Yes the larger turbos will "spool" but the car isnt going to leave very hard.

 

[Weather Man]

PM Dustin (CPRsm) and let him have a shot at your business. He flat out knows what works.

 

[wakebum2507]

It's a tough on for sure. If you want a really good spool time the 7675 is really nice. The issue with the 6R80 is you cant lug to motor down enough to really take advantage of the bigger turbo.

Yes the larger turbos will "spool" but the car isnt going to leave very hard.

Aaron,

so you think sticking with the 7675 with the 6R80 and converter combo will yield more happiness than going with a larger t5 or t6?

i'm really just trying to figure out what will work best, since this auto thing will be new to me. the 7675 worked great with the T56, but this is new territory for me.

i'm thinking about having a larger 4" DP made, since mine is 3.5 currently, and seeing if that helps with the flatlining from 6500 to 7K. i know those bigger turbos will be more linear in that area.

 

[CPRsm]

Pick the turbo for your HP goal. Big turbos leave the line just fine.

4,000lb car w 84/96 T6

 

[Aaron@JPCRacing]

I'm not saying its impossible. But you really need to look into what your doing with this car on a daily basis and what you plan to do with this car.

A 7675 is going to be a much more responsive turbo on the street which is why we offer it with our street kit. The down pipe really isnt that big of a deal we've made 1200+ with a 3" down pipe with our kit.
With the proper converter a 7675 will be way more snappy / fun on the street.

Dustin I can post slips all day of cars with our 76/75 kit going 9.0 - 8.9x. So a 8.7x with a 84/96 isn't that impressive.

 

[gimmie11s]

Subd

 

[CPRsm]

Dustin I can post slips all day of cars with our 76/75 kit going 9.0 - 8.9x. So a 8.7x with a 84/96 isn't that impressive.

I didn't post the slip because the ET was impressive. It was only 17-18 psi and just a LITTLE out of its efficiency range. Even though it is 2 tenths faster with 5psi less than the 76/75 in your kit. Our 76 has been 3 tenths faster than that and 7mph faster w still less boost than the 76/75. But ET was not the point. "Big turbos don't leave very hard." The 60 on that slip says otherwise. Especially coming in at 2 tons on the scale. The 60 was the only point here.

 

[Aaron@JPCRacing]

Trans brakes aside, for when your not at the track a 7675 will leave harder and spool faster any day of the week. This comes into play when your riding around town and out with your buddies on a Friday night. Which in all honesty is what most of these cars do. We try to focus on overall performance / fun and not just track performance as well with our street kit

Also a larger turbo will always make more power with less boost, thats just how turbos work. But your also sacrificing spool time with it. You can't compare a S400x chassis with a 96 turbine wheel to a small frame 7675. The S400 chassis has a massive exducer on both the compressor and turbine. That's not an apples to apples comparison. You can however compare it to our 7685 setups that have been well into the 180's


3950 w/ Glass roof and red interior. 18-19psi 6R80

 

[wakebum2507]

this car will be used for street sweeping, and some of the sub 1100hp rolling events. also might take it to wannagofast for a half mile hit or two.

motor isn't sleeved, so trying to keep it under 1000wheel, and looking for the turbo that will be most fun in that range, with the converter and auto.

the car made more than 1070hp thru the T56 on #18 (yes, more power than the current motor is safe at), so i know the 7675 has it in it.

just trying to decide if i should just leave it and be happy....but we all know how that goes.

 

[Aaron@JPCRacing]

same car spun a little bit but the mph at 21psi

View attachment 57590

 

[Aaron@JPCRacing]

this car will be used for street sweeping, and some of the sub 1100hp rolling events. also might take it to wannagofast for a half mile hit or two.

motor isn't sleeved, so trying to keep it under 1000wheel, and looking for the turbo that will be most fun in that range, with the converter and auto.

the car made more than 1070hp thru the T56 on #18 (yes, more power than the current motor is safe at), so i know the 7675 has it in it.

just trying to decide if i should just leave it and be happy....but we all know how that goes.

Personally I would rock out what you currently have and see how it does for you. More then likley you'll be happy with it as is.

 

[wakebum2507]

thanks for the input guys.

if this motor goes boom this season, i'll look at going T6 when I go sleeved. it's just money, right?

Aaron, you think there would be any benefit to going from a 3.5 to a 4" pipe?

 

[Aaron@JPCRacing]

Yea it's just paper. You can print more of it.


I don't see any point of upgrading it personally. If for some reason you still have measurable back pressure in the down pipe with the 3.5 you've got a restriction else where. Do you have it going all the way through to the rear bumper or does it dump under the car?

 

[wakebum2507]

Yea it's just paper. You can print more of it.


I don't see any point of upgrading it personally. If for some reason you still have measurable back pressure in the down pipe with the 3.5 you've got a restriction else where. Do you have it going all the way through to the rear bumper or does it dump under the car?

just dumps under the car.

 

[Aaron@JPCRacing]

Yea there should be absolutely no restriction in the pipe going straight to the ground with a 3.5" pipe.

 

[CPRsm]

Trans brakes aside, for when your not at the track a 7675 will leave harder and spool faster any day of the week. This comes into play when your riding around town and out with your buddies on a Friday night. Which in all honesty is what most of these cars do. We try to focus on overall performance / fun and not just track performance as well with our street kit


Also a larger turbo will always make more power with less boost, thats just how turbos work. But your also sacrificing spool time with it. You can't compare a S400x chassis with a 96 turbine wheel to a small frame 7675. The S400 chassis has a massive exducer on both the compressor and turbine. That's not an apples to apples comparison. You can however compare it to our 7685 setups that have been well into the 180's

Still missing the point. Apples to apples does not matter. "Big turbos don't leave hard." That's just not true.
Neither is saying a larger turbo will make more power w less boost.

Is this where I say "I'm not impressed w the 85mm?" And show you a slip of a 76mm with a turbine two sizes smaller at the same boost level? 15mph more at the same boost level, but the bigger turbo didn't make more power here.
3950 w/ Glass roof and red interior. 18-19psi 6R80
View attachment 57587

There is more to it that just saying bigger spools slower, or bigger makes more power.

 

[wakebum2507]

these numbers, are making me ready for this auto voodoo thingy to be in my car.

 

[2003mach1]

op: I love it!!.........

 

[Aaron@JPCRacing]

Still missing the point. Apples to apples does not matter. "Big turbos don't leave hard." That's just not true.
Neither is saying a larger turbo will make more power w less boost.

Is this where I say "I'm not impressed w the 85mm?" And show you a slip of a 76mm with a turbine two sizes smaller at the same boost level? 15mph more at the same boost level, but the bigger turbo didn't make more power here.


There is more to it that just saying bigger spools slower, or bigger makes more power.

I feel like your not grasping the concept here Dustin. Park a CPR kit and a JPC kit on the street side by side and put your foot to the floor.
Our kit will spool faster and be more responsive every day of the week. Thats where our kit shines and that's the reason we use the 7675 on our street kit.

I don't want to clog up this thread any farther.