A/R ratio for 427ci twin turbo....
10-29-2005, 06:35 PM
#1
A/R ratio for 427ci twin turbo.... What would the difference between a A/R ratio of .58 vs .68 on a 427 ci twin turbo. I know it will spool faster and be more limiting on the top end.....but can anyone be more specific??
I have read all about A/R ratio. I ordered 61mm twin turbos with A/R 05 .68.....but when they came they were .58's.....
Not sure if this will be a problem........
Tom
I have read all about A/R ratio. I ordered 61mm twin turbos with A/R 05 .68.....but when they came they were .58's.....
Not sure if this will be a problem........
Tom
10-29-2005, 07:02 PM
#4
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man that is a **** load of boost, however alot of the imports run a ton more boost, but they are smaller motors that require less consumption
you need to call a turbo expert, someone like Jose at forcedindutions.
they are a site sponser as well
ed
you need to call a turbo expert, someone like Jose at forcedindutions.
they are a site sponser as well
ed
10-29-2005, 07:14 PM
#5
I purchased the kit and turbos from Jose.....but they sent me the .58 instead of the .68 that I was supposed to get .68's.
I just dont want to hear....it will be fine...they are different for reasons....I wouldnt have been promised a .68 if I needed a .58.....so I am just getting opinions prior to calling
Tom
I just dont want to hear....it will be fine...they are different for reasons....I wouldnt have been promised a .68 if I needed a .58.....so I am just getting opinions prior to calling
Tom
10-29-2005, 07:33 PM
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I'm not an expert Tom, but I'd guess you went small with the 61mm's even in the .68 A/R. If you want to run 25 psi with a 427 ci (although I don't see how you're going to keep the cylinders sealed and round with so little wall thickness), I'd think you'd want something closer to 64mm's. 67's would certainly get the job done!!!
Jose should be able to answer you question although I understand your concern about an unbiassed opinion...
Do you have a compressor map for the turbos your received? If so, that would certainly help if you could post the map.
Jose should be able to answer you question although I understand your concern about an unbiassed opinion...
Do you have a compressor map for the turbos your received? If so, that would certainly help if you could post the map.
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10-29-2005, 08:50 PM
#8
I received no paperwork with the turbos.....nothing!!!
That also bothers me.....how do I know what I have???
I am running a C5r block...I am not worried about cylinder wall thickness. I am also running $1000 A1 Technologies MP-35 studs...270psi tensile strength, 90 ft/lb torque ...unless I have detonation I should be fine.
I may not run that high boost....but do not want to be limited if I decide to do so!!!
Tom
That also bothers me.....how do I know what I have???
I am running a C5r block...I am not worried about cylinder wall thickness. I am also running $1000 A1 Technologies MP-35 studs...270psi tensile strength, 90 ft/lb torque ...unless I have detonation I should be fine.
I may not run that high boost....but do not want to be limited if I decide to do so!!!
Tom
10-29-2005, 10:02 PM
#9
Those are going to spool really fast with either .58 or .68. I'm no guru, but I would have run a .81 on a 427 with 61MM turbos. Each bank of that engine will be a single turbo 3.5 L system and it will spool so fast you could have horrible traction issues.
You could have problems with exhaust backpressure as well. Trying to get 20-25 PSI on the compressor side could be rough... I could forsee 40 pounds of pre turbo exhaust pressure before you get that much boost out of it.
You could have problems with exhaust backpressure as well. Trying to get 20-25 PSI on the compressor side could be rough... I could forsee 40 pounds of pre turbo exhaust pressure before you get that much boost out of it.
10-30-2005, 12:00 AM
#10
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Hey Tom I think I might have talked to you on the phone? Any way we run .68 on our different twin apps, but all of them are GTballbering. Our new twin tubo kit is gt35rs with .68ar on my corvette and well see. Ralph
10-30-2005, 07:31 PM
#11
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We have no clue what you plan on doing with this setup....dragracing...road racing....grocery getter.....really depend on the application.....
Now my 408ci street/strip sbm(small block mopar) should be really fun to drive and post some good # 1/4 mile #'s....mid to high 9's...142-145mph at around 16-17psi...any thoughts from yall.
Now my 408ci street/strip sbm(small block mopar) should be really fun to drive and post some good # 1/4 mile #'s....mid to high 9's...142-145mph at around 16-17psi...any thoughts from yall.
10-31-2005, 06:23 PM
#14
Spoke to Dalton at PTK today. The turbos he sent were actually upgraded units sent by Precision. They are 66mm units. I purchased .68 A/R exhaust housings (allready ground the .58 units to get ready for coating...so they cannot be returned).
great service....
Tom
great service....
Tom
11-01-2005, 11:46 AM
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Originally Posted by tomulrich
The turbos he sent were actually upgraded units sent by Precision. They are 66mm units.
Those should get the job done!
