Reply With QuoteNice meeting and talking to you on the phone Brian(TurboNova). I look forward to working with you in the future on some of this stuff.
I have a 468 banks twin turbo with a single carb.
makes around 12 psi boost.
previous owner locked out the blow out valve on the intake side. he said it will blow fuel. what can I do to correct this.
also would like to set up a waste gate on the exhaust side between the turbo and manifold, need to find someone to fab the plate adapter when time comes.
http://www.***boat.com/image_center/...at6-med_1_.jpg
http://www.***boat.com/image_center/...46P1060006.JPG
Nice meeting and talking to you on the phone Brian(TurboNova). I look forward to working with you in the future on some of this stuff.
Carson uses on center housings which aren't very good exhaust housings but I don't doubt that he makes that kind of power with a 557. I agree it might be a problem in a closed cover compartment, I still think we could shield the exhaust housings and wrap the exhaust. Most drag cars have their exhaust housings within a couple of inches of the fiberglass hoods and have no problems. Carson's bigger turbos are GT42 with his water jacket housings which I still think is too small for that size of engine, close but not enough. The other choice he had was two 60-1s but they are way too small for a big block of that size. We can make that thing launch there are a number of ways. With a GT42 and the traditional housing that it comes with, it would be no problem. With the water cooled on center housing it might take some work.
Why cant you use garret gt47-88 or similar turbos and use them with the large gentry water turbo housings? KEEP IN MIND THAT ON A CAR SITUATION THAT THE WHOLE BOTTOM OF ENGINE COMPARTMENT IS OPEN TO AIR CIRCULATION. ON ONE OF MY BOATS IT IS TOTALLY ENCLOSED. nO AIRE TO ESCAPE ANYWHERE.
Why cant you use garret gt47-88 or similar turbos and use them with the large gentry water turbo housings? KEEP IN MIND THAT ON A CAR SITUATION THAT THE WHOLE BOTTOM OF ENGINE COMPARTMENT IS OPEN TO AIR CIRCULATION. ON ONE OF MY BOATS IT IS TOTALLY ENCLOSED. nO AIRE TO ESCAPE ANYWHERE.
You could but it would depend on if his housings would work with the exhaust wheel of the GT47-88 if they do then it would be a bolt on deal for the water cooled housings. When I talked to Carson he said that they used 60-1's (bad) or for bigger turbos he used the GT 42s. It also sounded like this was mostly salt water stuff from the rest of our conversation. His housings also used a pretty expensive internal wastegate, the size was good but the price was not.
Nice meeting and talking to you on the phone Brian(TurboNova). I look forward to working with you in the future on some of this stuff.
Thanks.
I have a 468 banks twin turbo with a single carb.
makes around 12 psi boost.
previous owner locked out the blow out valve on the intake side. he said it will blow fuel. what can I do to correct this.
also would like to set up a waste gate on the exhaust side between the turbo and manifold, need to find someone to fab the plate adapter when time comes.
http://www.***boat.com/image_center/...at6-med_1_.jpg
http://www.***boat.com/image_center/...46P1060006.JPG
With a draw thru a blow off valve isn't as important, it is easier on the turbo but isn't a problem for the carb. You will get some fuel out of the blow off because there is still fuel running through the turbo when you lift the throttle. Try not to instantly lift on the throttle then you will not have problems with the turbo. You can build a simple box between the turbo and the manifold that you can run a small piece of tubing into an external wastegate. It would have two four bolt turbo flanges. I believe you can buy these from Turbonetics
Here's a little info on rod length, since I saw that it was asked about. This is just "rule of thumb" mind you, but there are certain benefits from a shorter rod/stroke ratio (between 1.4-1.7:1) when talking about a supercharged deal. The biggest thing is that becausae of the increase in piston speed, the chamber volume increases more rapidly ATDC (on the power stroke), lowering combustion pressure, which delays the point of maximum cylinder pressure thereby taking the most advantage of the supercharger boost. (This goes for Nitrous, as well). Most BB Chev's are in the 1.5-1.6 range, and it's difficult to get any kind of a BBC stroker motor into the 1.6-1.7 range. This is one of the reasons why BB Chevs respond so well to supercharging. Short rod ratios also have certain advantages in NA app., but that's a different thread.
Short deck, short rod, big bore. I would think he 571, with it's 4.625 bore and 4.25 stroke, could be run in a short deck with a 6.385 rod and build excellent blown power. You also have the advantages of shorter pushrods, which helps with valve train stability. The engine is also simply smaller and lighter, if weight and/or space is a consideration.
This is a great thread. Turbo Nova, sounds like you know your turbo game. Good to have you here. Welcome
I am sorry and I don't want to rip on you or anything but a pair of 62-1's shouldn't be on anything bigger than a 350 small block and don't belong on any big block at all. I have been reading this forum lately and it seems like all the boat guys are stuck in the 70s with draw thru stuff and turbos that are too small. He is on the right track with the a larger turbos and if he is going EFI it has more to do with the EFI tune up than the actual A/R of the exhaust. I spool a 1.0 A/R with my small block with the right tune up and I am looking into changing the exhaust side to a 1.32 A/R. I personally wouldn't go any smaller than a .96 A/R on any big block and no less than a 74mm turbo. A couple of GT47s would work great on an engine like this depending on power band, heads ect..
I understand the reason for the water jacketed turbos and manifolds but you are actually hurting the performance of the turbo. The turbos spool with heat in the exhaust and the air flow coming into the exhaust side. If you water cool the housing you slow the air flow through the exhaust housing. I know this is a Coast Guard regulation but if you can stay away from it then do. The water cooled housings that I have seen are "on center" housings and are very old school. Very bad for flow and spool up. If you call a well known turbo supplier they will try to talk you out of running an on center housing because of the bad flow characteristics. The tanginal housings flow much better and look more like a snail shell. Even the GT42s you guys are talking about are too small for a big block of this size. I would first ask what kind of EFI are you looking at? Fast and Big Stuff 3 are a couple of the better ones out there for an affordable price. Then there is Motec, EFI Tech and Autronic. If you use a quality system then you should have hardly any spool up issues. Unlike a car, a boat has load and resistance in the water which will help spool up. Our 350 Chevy budget engine had a GT42 single turbo on it. I could spool it up at 2500 rpms with two carbs, if it was EFI then who knows. Exhaust housings are cheap and if spool up is an issue after the EFI is correctly tuned then change to a smaller A/R but don't put too smaller of an intake side on the engine.
I am a dealer for Precision Turbo and Engine, I sell Garrett turbos, intercoolers, EFI systems, piping, custom headers, all the stuff you would need to turbo anything. I do this for a living. You can make stupid power with the right turbo, EFI and a big block.
Don't worry about a rip or two - I don't agree at all with regards to the 62-1 being too small; I have them with an AR of 0.81 on a 472 Hemi in a street car and they spool at low RPM as expected and can provide up to 2.7 bar at 4500 and up. I do have both Waste gates and BOV's and they are all integrated into an Electromotive engine management system. Remember this is a street car and not something on the drag strip that is staged at high RPM.
Here is my math on sizing turbos for a 572 (the same method I use for all my turbo projects except for my draw thru BBC Jet Boat). Note that in this case at 5500 RPM the data point is to the left of the surge line. Secondly, if you should plot points at each RPM (which is really mass air flow) it ends up being virtually a straight line somewhat parallel to the surge line on the map. Typically, at some point as the plot (air flow) increases the mass flow will cross the surge line. In the case of this map my numbers show all points on the left of the surge line.
Engine parameters:
Displacement (EDIS) = 572 in3
Engine revolutions per Minute (ERPM) = 5000
Engine volumetric efficiency (VE) = 80%
Quantity of turbochargers (QT) = 2
Turbocharger compressor efficiency (EC) = 75%
Vacuum draw at compressor inlet (PVAC) = 2 in Hg
Turbocharger compressor outlet pressure (POC) = 22 PSIG
Engine manifold pressure (including intercooler losses) (PMAN) = 20 PSIG
Gas temperature at engine manifold (includes intercooler cooling) (TMAN) = 110 Deg F
Environmental parameters:
Ambient temperature (TAMB) = 80 Deg F
Local barometric pressure (PAMB) = 29.92 in Hg (14.7PSIA)
Molecular weight of air = 29.00
Solution definitions:
PIC = Gas pressure at inlet of compressor PSIA
DIC = Gas density at inlet of compressor Lb/Ft3
PRC = Turbocharger inlet to outlet pressure ration (P1/P2)
TOC = Gas temperature at outlet of compressor Deg F
DOC = Gas Density at outlet of compressor Lb/Ft3
DMAN = Gas density at engine manifold Lb/Ft3
PDROP = Pressure drop from turbocharger outlet to engine manifold (including intercooler) PSI
MAFCI = Compressor ideal air flow Lb/Min
MAFCA = Compressor actual air flow (based upon compressor efficiency) Lb/Min
1. Calculate inlet pressure conditions at the turbocharger compressor:
PIC = (PAMB-PVAC)*14.7/29.921
PIC =13.7 PSIA
2. Calculate inlet density conditions at the turbocharger compressor:
DIC = PIC*29.00/10.73* (459.6+ TAMB)
DIC =0.069 Lb/Ft3
3. Calculate turbocharger pressure ratio (P1/P2)
PRC = (POC+14.7)/ PIC
PRC =2.68
4. Calculate gas temperature at turbocharger compressor outlet:
TOC = (TAMB+459.6)*PRC^0.288-1)/ (EC+TAMB)
TOC = 315.8 Deg F
5. Calculate gas density at turbocharger compressor outlet:
DOC = (POC+14.7) *29.00/10.73* (459.6+TOC)
DOC = 0.128 LB/Ft3
6. Calculate gas density at engine manifold:
DMAN = (PMAN+PAMB) *29.00/10.73* (459.6+TMAN)
DMAN = 0.160 Lb/Ft3
7. Calculate pressure drop from turbocharger outlet to manifold (including intercooler):
PDROP = POC-PMAN
PDROP =3 PSI
8. Calculate ideal turbocharger compressor air flow:
MAFCI = EDIS/2/1728*DMAN*ERPM/QT
MAFCI = 72.8 Lb/Min
9. Calculate actual turbocharger compressor air flow:
MAFCA=MAFCI*EC
MAFCA=58.2 Lb/Min
http://www.***boat.com/image_center/...20/1030T76.gif
Results are:
Each compressor needs to flow 58.2 Lb/Min at a pressure ratio of 2.68 at 75% efficiency.
Show me your numbers cuz I don't understand your rationale......
Tom
Hi steelcomp and thanks for the input. We have decided to run .250" long rod (6.385") as you mentioned. I still haven't decided for sure if I will run aluminum rods or steel rods though I am leaning towards billet steel right now for longevity. I have heard of people running aluminum rods for years in their pleasure boats without problems but I have no expreience with them in those type applications.
Tom, you can crunch all the numbers that you want but I know what works. Call Precision Turbo and Engine, ask for Patrick 219-996-7832. We talked a couple weeks ago at length about turbos for a 572 in a boat, I was thinking about the GT42s and he still said too small use the GT47. A 60-1 or 60-2 isn't even close to the right combo with the heads and engine they are talking about using. In fact a T4 flange will really choke off allot of air flow. Tell him you want some turbo recommendations on a 572 with twins and see what he says. Don't believe me go to the source. Most of the twin turbo drag cars running this year were using either PT 80mm or 88mm with .96 housings or the GT47-80 or 88. I just go with what works, I am after the big horsepower stuff.
I have had guys from Garrett call and ask me what actually works as opposed to what they have crunched out on paper. Personally I believe your turbos are too small. I would have gone with bigger turbos but that is me, if you are happy with them then great.
Look up a compressor map for a 101mm Garrett and tell me how it crunches out too big for a 406ci engine at 7500-8000 rpms. Then with a 1.32 A/R instead of a 1.0 A/R. That is where I am going.
"Gas temperature at engine manifold (includes intercooler cooling) (TMAN) = 110 Deg F."
Your number here should be lower, we get intake temps more like 60-80, and you should get at least just above lake water temp. If your not then you have the wrong intercooler. We dynoed a BMW tonight and had intake temps of 110 Deg F without any intercooler.
Engine RPM is more like 6500-7000 not 5000, 5000 rpms is for ski boats. If you build a big block of this caliber using Oliver rods ect... why would you only turn 5000 rpms, you could do that with a stock bottom end!
Your calcs also don't take into account the huge flowing heads that the Profiler heads are. Are you saying that a stock set of chevy heads or Profiler heads should use the same turbo just because it's a 572? All I am saying is that there is more to the combo than just crunching air flow across the compressor map. Everything you are crunching is theoretical air flow not actual air flow through the engine, most VE will be greater than 75% mine is more like 85%.
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