the texoma run was the labor day run last year. we were told to congregate right outside the idle zone for highport marinas cove and that when all the boats were out there that flash would come out and pass back and forth three times with a yellow flag up and then after the third pass he would turn and put up a green flag and everyone take off. well I guess for the last couple years they had done that and when he gets out there all the big crusiers take off and make big wakes infront of everyone so last year for safety they decided when flash gets out there that he just put up the green flag and go. well we did not know that and since I do not have transmissions we were sitting there expecting to have several minuites when he got out there to go, so when he got out there and took off we were facing the wrong way with the engines shut off. all the boats leave, we get the engines started and take off trying to turn the right direction we get going and are probably #80 at the back of the pack so we start passing boats like an obstical course we decided to swing out around all the boats on the outside. after several miles we pass everyone but flash, hellion, dereberry and nashville. but we are gaining on them. so we just keep it to the wood and start turning the boost up. now we have caught nashville and were right behind hellion, we start smelling smoke check the gauges and there fine, we keep going, start seeing smoke, doesn't matter to me I dont care if were on fire i'm not letting off till we pass hellion. then my boost gauge starts dropping so we stay in it till we get beside him and wave then let off. open the hatch and see that a water line going into my aluminum headder is kinked and the header has melted all the powder coat off. and not having any water going into the header it has melted the inside and sent all that aluminum into the turbo. so our day was over but when we got back to the shop and took the turbo off it was fine, it just had a glob of aluminum blocking it and the inside of my exhaust pipe looked like it had a nice aluminum coating from the aluminum the turbo had chewed through. we actually still have that same turbo on the engine and it is fine.

there were a couple of the boats that had people videoing out of them that showed us flying by them that I saw on here awhile back.

Sounds Like a Blast,.......Are you running Crash Boxes then ?

Thanks
Jon

I agree and disagree with this statement. Turbo's, when talking about HP, are certainly better or at least, have more potential. Not that every turbo system is better, but from an engineering standpoint, they have potential to make 5%-15% more peak power (over screw and centrifugal). There also very quiet. There are also some airflow advantages, as it's being ducted to the inlet, you have more ability to send air into more concentrated area's, possibly run bigger IC's, possibly more effective heat transfer.

There are also huge disadvantages to the turbo though. First, lag, this is not an advantage. In marine envoirments, the turbo lag can add significant problems to plainning time or ability. With advances in transmissions and gearing, this can certainly be helped, but in the performance world, it's yet to be financially feasible for most. Also, lag time certainly comes into account for customer driving satisfaction. Lag comes into play during rough water operation, throttle on/off, as well as rpm limiters, which drops boost. You also have tremendous temps from the turbo's.

When emissions come into play, turbo's also cause issues with Cat light off time, as they can't spool up to create enough heat, and therefore turbo's in auto's are typically pretty dirty for cold starts.

Now comparing roots to turbo is no comparison, but a screw compressor can certainly have significant benefits. The centrifugal did not fix turbo problems, they were able to enhance the lag time, therefore it's better, yet still very, very there. Blower surge, boost drop off are all still there. Yet, you have the parasitic losses so you don't get that extra HP.

From what we see in the automotive OEM, there has been a tremendous surge for turbo's, and now we see a drop and a surge is coming for screw compressors, on diesel and gasoline applications. High boost levels, 20-30psi, smaller engines.

Thanks,
Dustin Whipple

no, I am direct drive, no trans at all. u-joint hooked directly to crank and drive shaft down to a straight arneson.

that is the reason we had to spin one engine the opposite direction. the bummer was when we wanted to spin my props in instead of out. think about that one. we had to pull the engines out and put them on the opposite side. it will sure be nice to finally have transmissions in the boat again next summer.

dont you love the way news orginazations can turn exactly what you say into something you dont mean just by leaving out certain parts.

but seriously, I do not think the lag is a big problem, mine did have some lag getting on plane due to a 1-1 gear ratio with a 34' prop, but after that the boost gauge would go up and down about as fast as your hand moved the throttle up and down. if you are saying that a tenth of a second of lag is going to mess people up I dont think so. I think the way a turbo works on load will help when you are getting on and off the throttle in big waves because if you go wide open throttle with a blower before you enter the water and break a drive or transmission because you landed with full hp and with a turbo you enter the water with wide open throttle it will only be half the power for a split second to let the trans and drive not get the shock load of full hp.

and I still say that most people do not know how to apply the situation, and some people may have turbos with way too much lag and there are alot of people out there that are only getting 30 min use out of a turbo and blowing it up, but mine does not have lag and I have the same turbos that we originally built the engines with 5 years ago.
Tyson

Hey Tyson, when are you going to let me build you an intercooler/intake/EFI?:D

Ive run twin turbos in a 30 ft Superboat with two small chevys for 11 years. Motors havent been removed from boat since installed in 1993. Have 1000s of hours on them in Mississippi River. Control the rpms, fuel, boost, hell everything it is the computer age. Use your brain not your check book. Try different things. It might work it might not. But dont wait for Merc to do it. And put some of that 6 figure paint on it. If Merc cant buy it, bolt it on, they wont do it.
Merc is still #1 with me. Where would we be without them.

Turbo's have to be matched to engine size and were the power range is desired. They can be used to boost low mid os high end. They can be matched for torq or HP. The variable geometry stuff can be matched to most all these isssues and sizing can be less of an issue. The variable geometry turbo's can also smooth over dips in the engines power curves.

Power can be had at low RPMs tons of torq. Turb's dont like a lot of overlap or duration lift is more important. Thus the hot cam stresses are not an issue. Economy and emissions are up do to less raw fuel being shot out the exhaust. O f course the guys that just want a lumpy exhaust note your out of luck.

Have seen a lot of big power N/A and blower boats having a difficult time hooking up out of the hole. Used to chuckle about turbo lag vs blower lag at the drags. Blower lag being smoking the begebies out the tires launching.

Can turbos be done cheep ... Well this 6cyl Rambler waggon we did turned 11s in the quarter. Was a daily driver took it to the strip 3 years after the last trip to the strip only didd 13s. After a couple days of scratching our heads changing plugs checking wires , distributor, compression we finally replaced the radiator cap we used as a intake manifold pop off valve and were back into the 11s.

I went with turbos on a boat when after driving my 16' Donzi classic decided I needed mufflers if one wanted to listen to the radio since the only muffler I could find were too big to install in the boat.
All this electronic gadgetry wow. Getting ready to go turbo again after threatning to on mmy last 3 boats. Now with boost referanced fuel pressure regulators, boost referanced timing retard, custom boost referanced carbs I will be whistling once again.

There is no doubt turbos are the way to go, smooth power all the way through if you use the right turbo application. I've played with them on cars for years, can't say much on boats though.........but I would believe it would almost factor the same if you set out and played with it long enough.

I can see your point in regards to less shock on the trans/drive, but in many applications, you need quick, repeatable, predictable power, when the inertia is not a factor for the drive/trans.

I personally drive a turbo diesel (were no new guess powered ones I could SC and tow boat), I also do many computer calibrations for other diesel applications. Were also heavily involved in some direct injected and diesel applications where we've been part of the testing of both, screw and turbo, and the majority of people are now looking for screw compressors as the future. No matter how good a turbo was matched to engine efficiency, optimizied psi's, etc, there is still lag. It's certainly gotten better over the years, but it's still there. Diesel applications make it worse, but it's still there.

In a racing application where acceleration is key, the lag is still typically a problem. Some laugh about traction, but the fastest cars, turbo'd or PD'd work on the traction in order for the car to go faster. To me, it's better to have the power at your finger tips, then not at all. If I want to give the motor/drive 1500lbs of torque at 2000rpm (just throwing # out there), then it's best to have it. The operator is in control of how much power to give the trans/drive by how much throttle is given.

Again, as I said before, the turbo's are incredible, and make mind blowing power levels, something no other force induction method can achieve, but drive-ability and emissions are simply not comparable. They may be plenty good for most consumers, can't argue that, but there is no comparison to drive-ability.

Thanks,
Dustin

The new adjustible inducer and exducers should take turbos way beyond any blowers as soon as they make them work.
Should be very little lag and alot of power.

What do they usually run $ ? I was thinking more like 500hp, those are big numbers.

if you only want 500 hp I would not waste the money doing a turbo set up you can easily get that naturally aspirated with SB2 cylinder head.

You can get 500 with a off the shelf AFR head.:D

I can't think of any reason why a turbo engine would last any longer than a supercharged engine, unless the supercharged engines don't have intercoolers, and/or they are running high boost with an inefficient supercharger (more parasitic drag). The engine's intake ports have no idea where the boosted air is coming from.

Michael

Seems at one point I was told one of the big life savers with Turbo's is balanced pressure. Turbo is pushing air in the intake side of the engine, but the exhaust side is pushing air into the turbo's so you have equal resistance on both side's providing harmony.

Blower is just slaming air into the intake side, with no resistance on the exhaust side. So you have a lot more volital atmosphere. Kinda like your valve train etc. is getting continually ***** slapped............LOL. Causing a quicker failure rate.

Turbo's have been around a long time as so many have pointed out. One there is more to understand, but two you were married to them in the carburetor world. Now that fuel injection and programable fuel maps etc. are off the shelf items, it opened up a whole new animal in the performance world and seem to be comming on strong in all performance arena's

Again just going off memory here.............

Jon

The reason a turbo engine goes longer between rebuilds than a comparable engine with a blower is the crankshaft on a blower application has the blower belt pulling on it and the bearings wear faster.

Don't forget the HP it takes to spin the blower! Try and rotate a roots and screw blower by hand, feel the resistance? On a 1000hp engine, the supercharger will probably take around 250-300hp. Atleast in the mustang world that was the rule of thumb. So, your 1000hp engine is making 1250 or 1300 or more.

With a turbo, it takes away very little hp, so a 1000hp engine makes only a little over 1000hp. These numbers aren't right on, but the difference is significant and why turbos are gentler on an engine.

Turbo makes more power with less boost.
A turbo dosent require radical cam specks..low duration and overlap. Low valve train stress.
At least on a car (boats a bit different) once a steady state speed is reached the turbo is just idling along not producing much boost and not soaking up much energy or stress on the engine.
Turbo's are or can be one of the most efficent devices there is at one time only a transformer was more efficent.

DonziJapan - I don't see what difference it makes what the output curve looks like, and which blower are we talking about, centrifugal or positive displacement?

courgarman - Don't see what difference it makes if the boost pressure is higher than the exhaust pressure. Neither type of engine uses much overlap anyway. Also a well designed turbo system also has higher boost pressure than exhaust pressure.

check300 - I can see on startup how the bearings could wear more with the blower belt, but if you've broken through the oil film while running, the bearing would get so hot it would seize.

Joe92GT - Agree the blower engine will need more overall horsepower output since some of it is going into driving the blower, and could reduce the life.

turbo2256b - Blower engines don't have radical cams either, or it will blow the fuel out the exhaust during overlap. Agree, more parasitic loss with the blower engine.

If you run any engine under boost, the life is going down. It's like running at full throttle and then some.

Michael

I dont get a quote?

Lmao... how are the Eickert headers working for you now?

$1.6 Million How is that for a Quote??:D

You must be refering to a B&M 420 or a roots from 1960. At 1000hp, a good roots should take approx. 150hp and a good screw would take 75hp.

Seperately, turbo motors typically require mid to high compression in the engines, to help increase low/mid range torque. This is also true for camshaft selection, unless you have varible cam timing, most require smaller cams that help increase cylinder pressure at lower speeds. A positive displacement, with high efficiency (screw) can run far lower static compression ratio's and much larger camshafts. Lower static compression allows the engine to have cooler temps/lower cylinder pressures while in 90% of operation. This means longer engine life.

To note, VW is set to release a new vehicle that has "compound boost" which has both a positive displacement and turbo. The turbo feeds the SC. By force feeding the PD, efficiency levels far exceed 100%, but when the turbo can't keep up, the increased vacuum and airflow from the SC helps fulfill that void.

Thanks,
Dustin

they work great for weight to hold down the cover for my jetski, when layed on there side they also work good for holding my mold a few inches off the ground. and I got one of the bums that walks by my shop picking up aluminum cans to sweep my entire shop for one of them.

so they are working out pretty good. although, I think for the $1800 I probaly could have hired some one to sweep my shop floor.

While this might be true in some applications, it isn't always the case. My engine is 6.5:1 static compression. The engine makes 2lbs of boost at only 1500 rpms. At 2750 it is already at 1390ft lbs of torque. The cam is not real small. It has 282 on the intake at .50. We limit boost with the ecu to 23lbs. I do run 100 octane unleaded fuel.

Tyson,

I think you have to answer the question to get quoted.:D

So with your education in the turbo world and everything you have learned good and bad.............why do you feel a Turbo engine is safer or will last longer than a blower engine of equal power in excess of 1000 H.P. ?

Thanks
Jon

Typicaly we built turbo engines with 10 lbs of boost and around 6 to 7.5 compression. One I remember was a 460 69 tbird single turbo. Pulled 800 lbs of torq if I remember correctly perty much from 2400 rpm to 5200. Turned 11.1 in the quarter mile weighed 5300 lbs.

Big thing with making them last was keeping the RPM low
hard core rotating mass parts as boost increases.
Have one friend that runs a 2000 cc lotus at 40 lbs of boost has busrted everthing in the car but the engine. He went as far as water cooled brakes and machining a billet transmission case for the car.
With the variable geometry stuff I did with the electronic controler boost was available at idle. First over the road truck we put one on when it took off all the drive wheels jumped off the ground at once. We then strapped it to the chassis dyno to dial in the power curve.

Been meaning to jump into this thread for a while, I've spent quite a bit of time with turbos!

The VW system quoted by Dustin above is the VW Twin Charger but you appear to have the operation the wrong way round: The SC feeds the turbo, not the other way around.

The supercharger is very highly gearing and is clutched. It is only there to fill in the gap BEFORE the turbo spools up to ensure good drivability. Since the turbo size no longer has to be compromised to give good response, the match can be a lot larger and so the performance ratio (remember this is a 170bhp 1.4l engine) can be a lot higher.

The SC is only there for response at the low end and has a very large drive ratio as it is clutched. It HAS to declutch before 3000rpm or it's exceed it's allowable max speed. This engine has already been released in the European market.

The SC does not take over when the turbo runs out of breath as you seem to suggest. This would not make sense as quite apart from the parasitic losses associated with an SC (as has already been discussed) as even a screw charger efficiency (isentropic effy) is nearly ten points lower than a typical centrifugal compressor eg the front stage of a turbo. So at max power where the losses are highest, the turbo takes over as it can provide the boost for the lowest cost.

Hope that helps!

Link to schematic: http://bioage.typepad.com/.shared/im...si_airflow.png

Turbo information
 

Don't yell at me because I don't post but this thread is up my alley. I was AMT Diesel, we developed all kinds of things for racing diesels and our designs made it into Cummins & Navistar truck engines - turbo and supercharged(roots)

We also ran the racing engines for Super Hero/Buzzi and my own little diesel boats here in the US years ago. We developed the small hi-po diesels that were to be marketed as small Seateks/Super Hero based on Cummins B series engines (also did C's and L-10's to compete with the Seatek)
I pride myself on the shear number of engines we have blown up on the dyno - in the name of developement & testing you have to break them.

Please ask Craig or Bud from Cig/Hawk who I am, no bull.

There are so many things being said here, if you have a question ask me and I'll answer it as best I can based on our cubic dollars of experience.

Joe Gere

Joe,
Thanks for the post, added knowledge is always welcome in my book. So Post away...............

Thanks
Jon

Any info would help I havent done this for 16 years or so. Trying to remember is tough with out getting out a lot of info and go through it. Have puut togeathe most of the parts I need to do turbos on my boat. Small blocks boost can range from 4 to 15 lbs or so. Planning on no more than 6 lbs to start out. Should put me in the torq range of a well built possibly short lived N/A BBC.

You asked for this so......

Componet wise a turbo will last must longer than the roots style blower that is on your boat engine, here are some reasons why:
1a - turbo bearings (non roller, no friction) are lubricated with engine oil presure and the oil is used to cool the bearings as well. The flow of oil takes a tremendous amount of heat off those bearings, the less heat and that fact that the turbo shaft similar toa crank shaft rides on oil and never touches metal means longer life.
1b - on your roots blowers the back bearing is a sealed roller bearing and the front are usally oil bath roller bearings. There is no way to get fresh lube or cooling to them - over time they will fail.****Please remember the roots blowers are from a 2 stroke DD that had oil galleries to feed and cool those rotor bearings. That's why you would see an old 6-71 go 15,000 hrs or more without ever touching the blower.

- like someone mentioned the amount of power and the strain on the crank to spin a blower is huge. We spent some time with the Top Fuel guys here at RacewayPark in NJ to really understand how to replace our turbos with blowers and the amount of HP that they consumer going through the traps was up near 1,000 hp. When that roots blower was in a DD it was a gear drive that didn't put any weight on the nose of the blower or drag on the crank. These things add up over time. The drag the blower makes verus the gains for us on the diesel just made no sense, plus the boost psi was not high enough. In our race engines we could hit 75 psi, you didn't have hose clamps and hoses on the air take side, they were machined slip connectors with O-rings and bolted together to prevent the boost from separating them.

- someone mentioned water cooled turbo houses costing power. Not at all, yes it is true that heat is what drives a turbo and a water jacketed housing could lower exhaust temps, but it's the expansion of the hot gases that is taking place before the turbo that actually drives it. If you were experiencing a cooling of exhaust gas problem you just need a smaller turbine, that's all.

- the real advantage a blower has is low rpm boost which a normal turbo set-up has trouble making. Here's the basic problem, we all now an engine is just an air pump nothing more or less. The faster it spins the more it pumps. When you compare gas rpm's (5,500) to a diesel rpm's (3,000) you can size a turbo on diesel much easy because the effective rpm range is no narrow compared to a gas engine. So, when you have a basic turbo on gas engine you ahve to size it to run at a higher rpm, thus no boost at the low end. The roots blower doesn't suffer from that.

Seatek had their version of twin turbo to overcome that low RPM power problem and we had our split housing single turbo.

Seatek used two turbos with a valve in-between the two of them. When running on one turbo you could only make so much power because your exhaust gas flow was cut in half, once exhaust back pressure was greater than boost pressure the engine runs flat, can't make 1hp more. When you open the valve the exhaust pressure dropped, the other turbo spins up and you effectively have double the air volume not double boost. This makes BIG power.

Our version worked like this. We use one large turbo with an axial divided turbine housing. When we needed low end power like getting on plane a diverted directed all the exhaust gas to the large dia side of the turbine wheel. This allowed ot to spin easier with less pressure because exhaust temps were low at lower RPM's. Again same problem as Seatek, our exhaust gas opening was restricted until yo make enough boost to open it all up and then your head snapped back!

Another huge problem with turbo engines racing offshore is as soon as you throttle back (leave the water) your exhaust temp drops like a rock and you loose so much boost, a blower stays constant it's mechanical driven, not gas temp. driven.

That problem is impossible to overcome, there are tricks to throttleing a turbo gas or diesel boat and that's why people don't like them - they are difficult to race with (at least years ago when we went in the ocean for 160 miles -LOL).

My opinion for what it's worth - if you wanted an engine to make lots of power for many hours and not run it like a race boat jumping wave to wave - a turbo engine is far superior.

If you want to run a boat the way we did, which was literally fly wave to wave a blower engine (gasoline) is so much better power wise and ease of throttling.

Bring on your re-buttals!!!!

Chief Engines 1200 Turbo's in a 47 Apache. They look great!
I would love to know how they run?
Ed

Comanche3Six - is your boat on a lift by the old River Edge or River Front Rest?

No

I assume you're talking about the old Waterfront Cafe?

That’s all very interesting. I sure do have a lot more respect for the turbo. Hell I've got one in my F-250. The convenience of boost adjustment is really nice. Blowers just look really cool though. Here at the University of Texas we have some very large diesel generators that use big ass turbo’s on each side of the engine (twin turbo) that feed a supercharger right in the middle. That’s totally awesome forced induction.

Panther - that's it Waterfront Cafe, we did a photo shoot there about 8 weeks ago and had dinner. I thought the place went down???

I understand what you are getting at, but they definitely have friction, viscous friction. Some turbo have ball bearings which have lower viscous friction for faster spool up.


A turbine is nothing more than the power side of a Brayton cycle engine. Lower the inlet temperature, and you lower the efficiency and power output. I've never seen any data on how much a water cooled turbine housing lowers exhaust temperature.


I think you are talking about a split scroll housing. Both sides of the turbine inlets go to the outside diameter of the turbine.

Michael