Looking for information for 572" twin turbo build

[Hipshot]

Busby, I think there is a little 1/8 mile bracket track near Lawton that still holds events.
Thanks for the added turbo info guys. As far as my bore and stroke combo goes I am going to run what I have because it is very nice stuff and it just wouldn't make sense to sell it and start over for a lake boat. My Donovan block is 4.625" bore and my crank is a Bryant billet 4.25" stroke.

[HeavyHitter]

Tom, maybe my math is wrong but it's always worked right for me in estimating Hp and sizing turbos. Let's see 25 psi gauge +14.7 to make absolute = P2. P2 = 39.7, P1 = 14.7. Therefore P2/P1 = 2.7, not exactly the 2.68 you used in your estimate but pretty close. I don't consider 25 psi recreational since it will require race fuel and good tuning not to fry things. A cubic foot of air at standard conditions weighs 0.076 lbs. Take a 572 at 5000 rpm. 1 cubic inch is 0.000578 cubic feet so the displacement in cubic feet is 0.331. Multiply that by 5000 rpm then divide by 2 for a 4 stroke and you get 827 cfm at 100% VE and pressure ratio of 1. Multiply by 0.076 and you get 62.8 lb/min of air flow. Multiply by a pressure ratio of 2.7 and you get 169.7 lb/min of air flow. Unless you really plan on putting on small heads without much cam your VE will be mid to high 80's so lets just use 86% for giggles. 169.7 x .86 = 146 lb/min. Use 2 turbos and that works out to 72 lb/min at 2.7 pressure ratio. That puts you real close to the 85,000 rpm 70% compressor efficiency intersection. OK let's figure this for 16 psi which is all I would run with composite head gaskets. That's a pressure ratio of 2.09. Take the 62.8 and multiply by 2.09 and you get 131 lb/min. That works out to ~66lb/min per turbo. On the compressor map that looks like 76% compressor efficiency and 70,000 rpm. Still over the sweet spot so good torque will start right around 48 lb/min. Let's work backwards to see the rpm. (48 x 2) / (2.09 x .076) = 604 cfm. 604/(.86 x .331) = 2121 rpm. To support 5000 rpm air flow you'll need 146 x 60 (min/hr) /11.5 (A/F) = 761 lb/hr. Divide that by 8 injectors and you'll need 95 lb/hr minimum. I'd stick with the 95's and turn the fuel pressure up since your next option is 160 lb.hr injectors. A 572 is a large engine needing large turbos. The super T were really developed for small engines pulling high pressure ratios and rpm to make the big horsepower numbers. Heat due to high exhaust pressures was not a big concern. I'd go with some GT-42 but I know they are pricey. TV-7X series will work well and are available remanufactured to help with cost. Does this make any sense? Hipshot call Scott at Turbos Direct in Phoenix. He can help you with what's available.

[TurboNova]

Hipshot
The Turbonetics Super-T series would be good for all out competition but, depending on the A/R of the turbines I doubt they would be good at all for anything else assuming you are going a duel setup on a 572. Make sure you check the trim; if the A/R is greater than .81 you may want to reconsider. Also for low gas flow rates on the compressor side (modest boating around) you would probably be really close to the stall area of the compressor (very bad). I have a pair of turbonnetics 62-1's (quite a bit smaller than the Super-T's) with a .81 A/R (P/N 10996) on a 472 Hemi and they stay spooled nicely right off idle. Also, the wastegates start stepping in at 4800 RPM at WOT when set for 18 PSIG so there is plenty of room on top should I decide to go there. The Super-T's have a big compressor so it takes a lot to get it turning.
Again, it's all what you are building the engine for. I recomend you visit the Turbonetics web site (Turbonetics (http://turboneticsinc.com)); they have all of their compressor maps, and a sizing sheet there. Lastly, call them - good knowledgeable people.
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.

[TurboNova]

Divide that by 8 injectors and you'll need 95 lb/hr minimum. I'd stick with the 95's and turn the fuel pressure up since your next option is 160 lb.hr injectors. A 572 is a large engine needing large turbos. The super T were really developed for small engines pulling high pressure ratios and rpm to make the big horsepower numbers. Heat due to high exhaust pressures was not a big concern. I'd go with some GT-42 but I know they are pricey. TV-7X series will work well and are available remanufactured to help with cost. Does this make any sense? Hipshot call Scott at Turbos Direct in Phoenix. He can help you with what's available.
Don't turn the fuel pressure up to band aid for too small of an injector. I have put 160's in 302 small block fords that idle well and street drive just fine. Again it is in the EFI tune. If you are making boost and say your base fuel pressure is 43 like it should be, then you crank the base pressure to 55 to fix the lack of injector at the high end then you would have something like 80psi @ 25 pounds of boost. Three things you are doing here, 1 is spraying more fuel at an idle by rasing the fuel pressure (maybe you can change that with injector opening time and maybe not) 2 increasing the amount of fuel available across the power band, 3 wearing out your injectors faster because of the extra pressure on them. You can actually run out of duty cycle doing this with too small an injector, the injector will actually hold completely open at max boost, it is also harder for the injector coil to accurately open and shut at extra pressures. Don't be afraid of 160s, people always say the idle quality is bad with 160s but that is only because they don't know how to tune.

[TurboNova]

A far better situation is to establish a turbo such as a Turbonetics T-62 or Garrett GT 42 and set maximum boost (25 psig for argument) at just less than 5000 RPM and have the waste gates control from say 4000 rpm and up. This way the turbine will spool at lower engine RPM's making the engine far more responsive.
The wastegates control boost as soon as the pressure comes to a point that they have to open to bleed off extra pressure to maintain the 25psi. They will not just control from 4000 and up. If the engine makes 25psi at 2000 rpms then the wastegates will open and control boost from then on. There are other ways to spool a larger A/R housing, I bet you guys haven't heard about putting another waste gate on the intake side. How about opening the BOV for a set amount of time to help the turbos spool. There are alot of tuning tricks, spooling tricks that will help you make more power faster without going to a turbo that is too small and will only choke your engine at a higher RPM.

[TurboNova]

Correct me if I am wrong,
Waste gates go on the exhaust side
blow off valves go on the intake side
should I be using both for proper performance
Yes and yes. You should be using both wastes for control and blow off or sometimes called surge valve for relieving pressure from the intake tract when you lift on the throttle. This is alot easier on the turbos and you will not try to spin the turbo backwards when you lift on the throttle.

[TurboNova]

Probably need 4 waste gates to hold pressure. The right sized GT or older TV, TA series turbos can flow much higher exhaust volumes so the overall system efficiency is better. If you want to pull the big pressure numbers you'll have to make sure you o-ring the heads and receiver groove the block.
Two HKS GT or GT2 wastegates would work just fine. I agree I would O-ring and reciever groove the heads anyway.

[Unchained]

Turbo Nova,
Thanks for all that tech info.
I've spoke to Heavy Hitter several times and he has really helped me figure out the specifics on turbos and EFI systems too.
I can't complain about the drivability with the 160# injectors.
I'd use that size again in a second.
I did drop the fuel pressure down to 36# and that lets me run 1.7 ms injector timing at idle and I'm at 6.5 ms at WOT / 19# boost.
Maybe people who didn't have good luck with the big injectors didn't have a good strong trigger signal. I wasted a lot of time trying to use the signal from the MSD distributor before I went with a crank trigger Hall effect signal setup.
From my experience that is the only way to go.
There is a lot of interest in Turbo / EFI here on this site judging from the PM's I've got about it and help from the pros is invaluable.
I've got many mixed opinions about me mounting the wastegates right on the turbine housing. I've seen it pictured in the Maximum Boost book as being an optimum place to mount them. I might not want to do it with some expensive turbo's but I don't mind machining on the turbine housing of these Diesel turbos. It has worked out real good for me.
http://www.***boat.com/image_center/...gatemount2.jpg
http://www.***boat.com/image_center/...egatemount.jpg
http://www.***boat.com/image_center/...erightside.jpg

[TurboNova]

Turbo Nova,
Thanks for all that tech info.
I've spoke to Heavy Hitter several times and he has really helped me figure out the specifics on turbos and EFI systems too.
I can't complain about the drivability with the 160# injectors.
I'd use that size again in a second.
I did drop the fuel pressure down to 36# and that lets me run 1.7 ms injector timing at idle and I'm at 6.5 ms at WOT / 19# boost.
Maybe people who didn't have good luck with the big injectors didn't have a good strong trigger signal. I wasted a lot of time trying to use the signal from the MSD distributor before I went with a crank trigger Hall effect signal setup.
From my experience that is the only way to go.
There is a lot of interest in Turbo / EFI here on this site judging from the PM's I've got about it and help from the pros is invaluable.
I've got many mixed opinions about me mounting the wastegates right on the turbine housing. I've seen it pictured in the Maximum Boost book as being an optimum place to mount them. I might not want to do it with some expensive turbo's but I don't mind machining on the turbine housing of these Diesel turbos. It has worked out real good for me.
http://www.***boat.com/image_center/...gatemount2.jpg
http://www.***boat.com/image_center/...egatemount.jpg
http://www.***boat.com/image_center/...erightside.jpg
If you had something other than Halltech then you could tune the injector instead of messing around with the fuel pressure. I run all my stuff at the rate the injector is flowed at which in most cases is 43psi. Then we tune the EFI system from there. One of the best systems for leaning out idle is the Big Stuff 3 EFI system. There is a table for injector opening time vs voltage that we use for idle injector opening and ramp the injector up as the alternator starts working. We have made small cubic engines idle very well with large injectors.
As for the wastegate you could mount them just below where the turbo housing flange is and accomplish the same thing without going through all that trouble. Most people mount the wastegate coming off of the collector or build a box that bolt between the turbo housing and the header collector I have not seen any other person other than you who mounted their wastegate there. I am not saying that it is a bad thing but I would think that it might hurt some of the flow going into the housing. Hey some of the guys we race with will spend tons of money for every last Hp and if the wastegate on the housing was the way then everyone would be doing that by now. Garrett would be building them that way.
Remember that the Maximum boost book is old technology, some of the same stuff applies but turbos have changed alot in the last 5 years as well as wastegates ect...
Our boat will be in the new update of the book "Turbochargers" coming out sometime in Jan. from what I am told by the author.

[Hipshot]

As unchained mentioned thanks for the information. I really have to get to work on this deal a little harder I just need to make some phone calls I guess. I really need to learn to read the turbo maps better. My only hold right now is deciding what turbos to go with. I almost bought the SuperT's but didn't after being told they weren't optimal. I have been told by a few folks supposedly in the know to look at the Garrett GT-42s so I have been looking around for deals. I just don't want to plop down $1800-$2500 on turbos without getting the right ones. Any more input on my combo would be super!