twin turbo question

[Vendor Defendor]

i was talking with WakkoSS the other day, and for some reason twin turbo setups came up as the topic. and then we got to thinking, and i figured someone here could answer my (our) question..

when you set the boost on your turbos, do you set them individually for lets say 15psi? because 15psi+15psi=30psi or do you set them both to 30psi and just get double the CFM's, but maintain 30psi?

i hopy you understand my question..


thanks for any info..

-Neil

 

[John Wilde]

The pressure is the same and is not equal to x 2.
Twin turbo cars running 15lbs of boost are running 15lbs not
30lbs!!! If that were the case imagine the boost Mike Moran must have run in his 4 turbo big block chevy =)
Yes you do get double the cfm.
From what I have been reading from a Garrett Engineer a big single turbo is more efficient than a twin turbo set up to make the same power. This is not always the way to go depending on what class your car is running and what the transmission limitations are. On a v-8 they have made a 106mm turbo work with an automatic. You had to really abuse the converter to do this though. With a Clutch Car it is a piece of cake. Bounce it off the 2 step at 5000rpm and dump the clutch. The v-6 has much less exhaust velocity and has a problem with spooling the bigger turbos quick enough for a pro tree. Several people have the 88mm turbo down. Jumping the the next level of 91mm-100mm is another story. Alan Witter had some problems with a larger turbo.
I have heard rumors of another famous buick racer using nos to get his big turbo to spool. Dale Cherry is working out a 101mm turbo on his car. I am not sure if it is race ready. Richie Kibler will be testing a new 91mm turbo from PTE this year. It was designed to spool on a v-6 and make 1500hp. That should the hot ticket.
Rick Head at Innovative might build a 94mm for a customer of duttweiler's. That should be able to push the hp limts of the v-6 motors. At the higher levels it would be easier to race a twin turbo set up on a v-6. That does not mean you can not make the single work.

BTW some of the v-8 and v-6 guys are running up to 10.5 to 1 compression to get their turbos to spool.

 

[turbolou]

Question

I have seen turbo race cars with clutchs useing a blow off valve on the compressor side of the tubeing just before the throttle body. The wastegates are left closed & boost pressure is exhausted or controlled on the pressure side. This allows the turbos & engine RPM to come up quickly against the two step. By closeing the blow off valve with a solenoid & with the turbos already spooled up the car launches hard. Has anyone tried this method or a variation of it on an automatic car with any success?

 

[John Wilde]

Lou,

I think I have seen that with several Out Law 10.5 Mustangs.
Dennis Ramsey, Elias Delatorre and Matt Scranton all come to mind.
I am not sure of Dan Millen or Tim Lynch.
It must work very well. Never seen it on a buick yet.

 

[turbolou]

Originally posted by John Wilde
Lou,

I think I have seen that with several Out Law 10,5 Mustangs.
Dennis Ramsey, Elias Delatorre and Matt Scranto all come to mind.
I am not sure of Dan Millen or Tim Tynch.It must work very well. Never seen it on a buick yet.

Thanks John!The particular car useing that system that caught my attention was Rieger's 57 Chevy. I got a chance to study it close up & found it rather interesting. Given the fact that person could afford the best technology & the car worked very well. I also am reflecting back to my own experience trying to come up with a combination back when I was racing my TT V/6 regal. Those damn V/8 mustangs back then with blowers & nitrous & lighter had a totally unfair advantage on the starting line. While us Buick guys were sitting at the line trying to build boost & leave on a pro tree. So that in my opinion is still the greatest challange for a small displacement turbo race car & someone brilliant enough to come up with a solution.

 

[Kansas T]

Anyone know how the blow off valve is plumbed to control the launch presure?

 

[John Wilde]

Lou,

They were also using co2 to pressurize the wastegate.
Tell me more about your project when you get a chance please.

 

[EightSecV6]

Conley originated the blow off on the compressor side, Tweaked 1 used it with that Big Brute lock up glide and he now uses it with the clutch in T2. Dale Cherry uses it now, Alan Witter has it, Randy Eakins uses it too.
I didnt have anywhere to put one in my plumbing or I would have had it as well. I use strictly the Innovative boost controller with Dual Racegates, of course there are very little spooling issues with a clutch, My PT98 will come up to 16# in less than a second.
Bill

 

[John Wilde]

Bill,

Thanks for the info.
Take your car out please!!! =)

 

[turbolou]

Originally posted by John Wilde
Lou,

They were also using co2 to pressurize the wastegate.
Tell me more about your project when you get a chance please.

Glad you asked John! I'm currently working on a stage 2 conversion in a 87 regal I think I have all the details covered except for the throttle linkage & cables. The F.I is the usual four barrel intake with a PTE doghouse. I have not researched a throttle body as yet. To see what my options are. Right now I'm in the process of assembling the engine & gathering parts & information. I'm sure that I will have a few questions as I go along. My goals are to provide a reliable fast street machine of about 750 H.P. I may be dreaming but I would like to run the stock computer if I can. These projects for other people keep me busy & away from me flipping out & building another race car. It kills me not to be out with there mixing it up with some of the other fast Buicks. So for now this will have to do. Regards Lou

 

[EightSecV6]

Originally posted by turbolou
I think I have all the details covered except for the throttle linkage & cables. The F.I is the usual four barrel intake with a PTE doghouse. I have not researched a throttle body as yet.

I have done it 2 ways, you can use the Accufab 70mm Buick throttle body and make an adapter from a 1/4" aluminum plate, modify the stock throttle bracket and attach it to the rear plenum mounting stud and the stock cables will work.
You can also use the Ford style throttle body and use a Lokar street rod cable which attaches right to a stock gas pedal, either way is not difficult. My website will be up probably tomorrow and it has pictures of bot methods


John, the car will probably not be out until Bristol (maybe Morocco) but I am pretty sure we will be capable of putting a number down at either race, we'll see.........

 

[turbolou]

Originally posted by EightSecV6
I have done it 2 ways, you can use the Accufab 70mm Buick throttle body and make an adapter from a 1/4" aluminum plate, modify the stock throttle bracket and attach it to the rear plenum mounting stud and the stock cables will work.
You can also use the Ford style throttle body and use a Lokar street rod cable which attaches right to a stock gas pedal, either way is not difficult. My website will be up probably tomorrow and it has pictures of bot methods

John! I have acquired a 90 mm ford accufab throttle body & an intermediate spacer plate that goes between the T/B & doghouse it has a throttle bracket provision also. Correct me if I,m wrong but it seems that the throttle linkage arm wants to be mounted in an upward position. Instead of the side. I think that I can make that work. But will it clear the stock hood? If not there is at least 3/4 " that can safely be machined off the base of the dohouse. My other concern which I have not researched is how well will the Ford IAC & TPS sensors react with the factory harness I intend to use. Is it just a matter of changeing connectors Regards lou

 

[Mac in SD]

Lou, I just used an adaptor plate and a Hemco upper, with a 70mm stock replacement-style TB. I attached the throttle cable bracket to the plenum using the two small screws on the plenum. Pretty simple.

 

[turbolou]

Originally posted by Mac in SD
Lou, I just used an adaptor plate and a Hemco upper, with a 70mm stock replacement-style TB. I attached the throttle cable bracket to the plenum using the two small screws on the plenum. Pretty simple.

Thanks Kean! I didnt know that hemco made an upper elbow that will bolt to a stage four barrel intake? I will look into that for sure.

 

[Mac in SD]

Whoa, there big fella!

Hemco makes a plenum to fit a stock intake, which must be attached to an adapter plate to fit the 4V. The good thing about the Hemco is that it's outlet into the manifold is more square, and fits within the plenum opening of a 4v manifold. You still need an adapter plate, though. The other good thing is it's not as tall as one of those PTE (?) elbows, so's it fits under the hood with more clearance, and doesn't look radically non-stock to the uninitiated.

Morgan took some pix of my car a week or two ago. If he ever gets around to sending them to me, I'll post them.

 

[turbolou]

Originally posted by Mac in SD
Whoa, there big fella!

Hemco makes a plenum to fit a stock intake, which must be attached to an adapter plate to fit the 4V. The good thing about the Hemco is that it's outlet into the manifold is more square, and fits within the plenum opening of a 4v manifold. You still need an adapter plate, though. The other good thing is it's not as tall as one of those PTE (?) elbows, so's it fits under the hood with more clearance, and doesn't look radically non-stock to the uninitiated.

Thanks again! I would really be interested in how that looks & if there are any downsides?

 

[The Radius Kid]

Originally posted by turbolou
Thanks Kean! I didnt know that hemco made an upper elbow that will bolt to a stage four barrel intake? I will look into that for sure.

Last I heard,Ralph[?] at Hemco was working on something for the four barrel intakes,but it could have been a rumour.