Turbo size for a TT 427?
Thread Starter
TECH Resident
iTrader: (13)
Joined: Feb 2012
Posts: 821
Likes: 0
From: Harford co. MD
So i'm down to two units Comp 6767 Billet BB or 7075 billet BB a/r up to .96 i think.
I think the 67's will get me close to 1300whp if i wanted and probably spool almost instantly just dont know if i should go a bit bigger?
I think the 67's will get me close to 1300whp if i wanted and probably spool almost instantly just dont know if i should go a bit bigger?
I just received Comp twin 7275s 0.84 A/R from Jon at Huron for my 408ci Manual ZO6 I really think with stalled auto and 427ci you can go anything from 67s to 80s all depends on how fast you want the car to spool , Crazy mid range power ,and how much are RPM are you planning to go , Dig runs or Street car , Highway 150+mph runs?
I went with slightly bigger turbos hoping for a better traction with my light ZO6 Looking for 3500-3800rpm spool and shifting around 7000rpm with the right cam.
I went with slightly bigger turbos hoping for a better traction with my light ZO6 Looking for 3500-3800rpm spool and shifting around 7000rpm with the right cam.
Thread Starter
TECH Resident
iTrader: (13)
Joined: Feb 2012
Posts: 821
Likes: 0
From: Harford co. MD
Mine is mostly a street car with some 1/4 mile hops. I think the 67's will spool very fast and the 72's should be a bit lazier on the bottom. Comp said the 67's will make that power no problem and still have some left.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
FormerVendor
Joined: Dec 2001
Posts: 2,444
Likes: 2
From: WWW.SPEEDINC.COM
Well there isn't anything about this that is a guess. Detail exactly what you want and their will be a pair of turbos that match that goal.
For example, GT3582R's will make 1000rwhp and make peak torque at just over 4000 rpm.
6766's will do 1300+rwhp and make peak torque around 5000rpm
7675's will do close to 2000rwhp and make peak torque around 6500rpm.
The above are just examples and would change quite a bit depending on the exact combination but still realistic trends. Keep in mind that peak torque on a turbo car will usually coincide with where it initially made peak boost and you can see that as you go up in turbo size/power potential you are shifting your power curve higher in the rpm range, sacrificing low and mid rpm power and response as a result.
Once you get up past 6766's or so, in my opinion you will need to switch to a solid roller in order to have the rpm capability to match the turbos or you will end up with a very narrow powerband. (You will need to shift it before it makes peak power)
For example, GT3582R's will make 1000rwhp and make peak torque at just over 4000 rpm.
6766's will do 1300+rwhp and make peak torque around 5000rpm
7675's will do close to 2000rwhp and make peak torque around 6500rpm.
The above are just examples and would change quite a bit depending on the exact combination but still realistic trends. Keep in mind that peak torque on a turbo car will usually coincide with where it initially made peak boost and you can see that as you go up in turbo size/power potential you are shifting your power curve higher in the rpm range, sacrificing low and mid rpm power and response as a result.
Once you get up past 6766's or so, in my opinion you will need to switch to a solid roller in order to have the rpm capability to match the turbos or you will end up with a very narrow powerband. (You will need to shift it before it makes peak power)
As mentioned I went 6768's. I told John I wanted to make over 1k rwhp through a 418 with a big stalled glide / 9" and tap the 8.50 cert cage my truck has at 3, 300lbs while keeping a 7, 500 rpm shift. Most likely I will swap back to an 80e and put a 3.73 gear with a bit tighter verter, but by the looks of the 6768's I will still hit my goals if I make that change.
Thread Starter
TECH Resident
iTrader: (13)
Joined: Feb 2012
Posts: 821
Likes: 0
From: Harford co. MD
I dont really want to spin it much past 7K and maxing out at 1300whp would be fine at what boost would it take the 6766's to make that power and what is their power curve?
Is it safe to say the Comp 6767 is very close to the same as the PTE 6766 spec wise they are almost spot on?
Is it safe to say the Comp 6767 is very close to the same as the PTE 6766 spec wise they are almost spot on?
On what fuel? My motor isnt lsx but it has cubes and good heads but its low comp and alittle loose, it took 24 psi to break 1000 thru a big stall th400. But pure 93 oct gas only. Higher comp and even better heads like 15 deg ls stuff will likely make same power on much less boost but reach a threshold on pump sooner perhaps. Depends on where that power is made and how hot iats are. 1300 is a hell of alot more and if you dont spin past 7k, you'll need alot of boost.
But dont be afraid of that just keep it cool
But dont be afraid of that just keep it cool
Thread Starter
TECH Resident
iTrader: (13)
Joined: Feb 2012
Posts: 821
Likes: 0
From: Harford co. MD
Mostly pump gas but if I need to turn it up I can get 112 fairly local. Comp is 9.5-1 heads are ported LSX ls7 that flow very well and its getting a custom IC good to around 1500hp made by Chiseled so that should help! Should I go with the larger .96 housing with the 6767's ?
Thread Starter
TECH Resident
iTrader: (13)
Joined: Feb 2012
Posts: 821
Likes: 0
From: Harford co. MD
I'm really leaning on the side of the Comp 6767's from what I found they are almost the same specs as the 6766 PTE units and the BB units are way more reasonable.
I just have to figure out what size housing and divided or undivided!
I just have to figure out what size housing and divided or undivided!
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Unless you have full tubular manifolds leading to divided collectors, then there is no benefit at all to running a divided housing. In fact, that is the only reason you'd ever want to use the divided housings.
Dont forget though, 76's are too bit, but Precision, Comp etc all make a good few units in between 67 and 76 too.
There is no lack of models to choose from !
Dont forget though, 76's are too bit, but Precision, Comp etc all make a good few units in between 67 and 76 too.
There is no lack of models to choose from !