Mercury's Turbo Engines
12-19-2009, 06:55 PM
#52
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Every thing i have driven with a turbo suffers from lag,diesel truck big time,honda jet ski some ,wrx some,old gale banks bb big time,now i am sure the new modern ones much better and having 4 could work good,but would be very expensive and hard to work on,the twin screw blowers work great on boats have awesome throttle response and working on the engine is easy.
And they we´re routed just like told above... also pushing unburnt fuel in the turbos exhaust housing made wonders in SAAB´s... you just hooked the idle injector to the brake pedals rearlight switch... yea a foxtail followed from the exhaust
12-19-2009, 07:13 PM
#53
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The problem with lag in a offshore pleasure boat is when the water get real rough cruising around 3500-4000 coming off a big wave and start dropping into hole you need that throttle response to keep on top a brief delay drops you in the hole and could get you into trouble,now if you are running 4500-6000 throttle response is much better and not really a problem,I have found the procharger systems have the same lag issues at the 3500 rpm range,now if you run in flat lake type water not really a problem and turbos and procharger style blowers make a lot of power and can give you some really good top end speeds,I guess volvo had it figured it out years ago on there deisels have the motors boost on screw blowers on bottom end let the turbo kit in the mid and top,cut the screw blower off up top have the best of both worlds
12-19-2009, 07:22 PM
#54
Banned
I guess volvo had it figured it out years ago on there deisels have the motors boost on screw blowers on bottom end let the turbo kit in the mid and top,cut the screw blower off up top have the best of both worlds
Sounds like a great solution
what vehicles did they do that on?
Sounds like a great solution
what vehicles did they do that on?
12-19-2009, 07:58 PM
#55
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i have been watching this post,ok here,s my 02 cents.as allready stated ,turbos can,and do make big hp and torque,and the exhaust is much quieter,and many have been 1 offed in boats,but with the psi and whipple screw chargers,the parasitic loss is way down compared to roots superchargers.as brad stated,if you are in rough water,and are lifting off and then getting on the sticks,even a small amount of turbo lag is bad.if you do this kind of boating,the turbo probibally is not for you.if your style of boating does not require you to get off&on the sticks,a turbo might be what you need.will turbo,s take the performance boating world over,i dont think so,will the roots blower go away,i dont think so.will mercury and some other engine manufactures install screw blowers on their hp engines,THEY ALREADY DO.will they be switching to turbo,s in the near future,well just have to wait and see,my guess is,NOT IN THE NEAR FUTURE.i would have to say,as much as i love turbos,they wont replace the screw charger.
12-19-2009, 07:58 PM
#56
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Yes, they actually do, the only time they "build-up" more boost is when cams fall off. Most engines have a 2psi swing from 1500rpm to 6000rpm when cammed properly. 1000ft lbs on a motor that makes 24psi peak is actually quite low. Make 1000lbs @ 2200 on an engine that makes 10psi peak because thats what a twin screw does. If you run 24psi, your in mid rpm range, and sorry, 24psi is not in any production engine realm for gasoline. Put a twin screw at 24psi and see what torque it makes at 2200rpm. That would be if you could actually hold it there with that amount of torque, because it would have 22-23psi right there.
Let me clarify a few things. Bill said "Our engine is over 1000 ft lbs from 2200 rpms on up" and did not say that that was at 24 psi. In reality the motor makes 5psi boost and 744 ft-lbs @ 1750 rpm, and is up to 1389 ft-lbs @ 2250 rpm with 15 psi boost. As far as running the motor at 24 psi, your absolutely right, we're not running gasoline. We're also not adding a ticking time bomb to the mix by adding meth injection like so many like to do today. Not to mention we are nowhere near the 8.5-9.0:1 cr that I'm sure you think we are.
"Put a twin screw at 24psi and see what torque it makes at 2200rpm" That would be great if you could do that, but I didn't think you could load an engine that low. If I recall:
If this appears as though I'm questioning your intelligence, I apologize. I know you have much more experience in this area, and I know that superchargers are a great way to make power. I simply want to have the current information out there.
12-19-2009, 07:59 PM
#57
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The problem with lag in a offshore pleasure boat is when the water get real rough cruising around 3500-4000 coming off a big wave and start dropping into hole you need that throttle response to keep on top a brief delay drops you in the hole and could get you into trouble,now if you are running 4500-6000 throttle response is much better and not really a problem,I have found the procharger systems have the same lag issues at the 3500 rpm range,now if you run in flat lake type water not really a problem and turbos and procharger style blowers make a lot of power and can give you some really good top end speeds,I guess volvo had it figured it out years ago on there deisels have the motors boost on screw blowers on bottom end let the turbo kit in the mid and top,cut the screw blower off up top have the best of both worlds
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12-19-2009, 08:48 PM
#59
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on a old style setup you will have lag, but on a modern setup when you back off the throttle the turbo DOES NOT slow down, so when you add throttle the turbo boost is there due to the bypass valve, on the old style they used a pop off valve and the boost dumped into the air, lost power ect.
Last edited by H2Xmark; 12-19-2009 at 08:51 PM.
12-19-2009, 09:59 PM
#60
on a old style setup you will have lag, but on a modern setup when you back off the throttle the turbo DOES NOT slow down, so when you add throttle the turbo boost is there due to the bypass valve, on the old style they used a pop off valve and the boost dumped into the air, lost power ect.
The technology is WAY better than what it was 15 years ago. I think we all agree on that. What we will all argue about is which is better.
Well.......Ford or Chevy.
