Inline6Merc
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What would be better on a inline6 200, Supercharger or Turbocharger?
Supercharger or Turbocharger???
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Anonymous
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PEPSI....it sits better in my tummy....coke just makes me feel BLAH 
i like a turbo too cause its on demand, although if i could get a really cheap super i would put it on just cause all the guys would see it and OOOO and AAAHHHH over it a little more.
i like a turbo too cause its on demand, although if i could get a really cheap super i would put it on just cause all the guys would see it and OOOO and AAAHHHH over it a little more.
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Anonymous
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I hate to disagree with my man Slade, but the numbers don't back up his conclusions. Here's a scanned image from last year's HRM's Turbo-Roots-Centrifugal Shootout (all three tests done on the same engine, back-to-back). The advantage in every way goes to the turbo for the critical 2500-5500 street RPM range. Period. Dot. End-of-conversation. A turbo is the easiest and cheapest to install, as well. Install a blower if you like them, but the answer to Inline6Merc's question is unequivocal.CobraSix":3cfkwl80 said:
My two cents? Who freekin cares? Lets boost the pajamas of every six we own!
I'm certain if the right kit was avaliable, there would be similar power from a 6 psi turbo as a 6psi blower, or a 12psi turbo verses a 12 psi blower.
Circumstances alter cases. Some important points which influnce the decision.
1. For each dollar, you'll get more power from a turbo because they are easier to size, easier to intercool. You'll get similar fuel economy for each extra hp if your using a carburettor.
2. Rated boost for boost, with no intercooler, there is little difference between turbo and a postive displacement blower. On a non-cross flow six, there is so much space for a blower or a turbo, so you can't go wrong.
3. Fuel supply for turbos needs more attention. An EFI turbo will give more power with less fuel than a GMC 4/71 with a Holley. A blow through turbo will suffer delivery problems when the boost goes up.
4. A centrifugal blower will always be harder to get the most out of, but is one of the easier conversions around.
Whenever I consider a turbo or a supercharger, I ask myself, will it take 12 pounds of boost. 12 pounds is the stock hp, times 1.65 in most cases.
As a teen, I studied both. Hot Rod did some great testing back in the 80's. Take one 300 hp 350 V8. Add a 6/71 blower at 12 psi , and get an awesome 490 HP. A Megacharger, less, a TO4, about the same. But the Rootes blower will suck a lot more gas.
When I see stock belt drives like this on Tempos, Topaz, Taurus 2.3/2.5 I4's which our cars share bits with, I'm thinking a 400 buck Ogura supercharger running 7 pounds of boost would make a great replacement for an air pump or power steering unit!
Or a Holley 1949 air cleaner mouth for three Holley 1949's on a six.
People rip SC12 and SC14 blowers out of 1988 to 2001 Toyotas, and they bolt on an on demand 25 to 35% with just the flick of a fan clutch. Hello, 25 to 60 hp on the swithch, dudes!
I'm certain if the right kit was avaliable, there would be similar power from a 6 psi turbo as a 6psi blower, or a 12psi turbo verses a 12 psi blower.
Circumstances alter cases. Some important points which influnce the decision.
1. For each dollar, you'll get more power from a turbo because they are easier to size, easier to intercool. You'll get similar fuel economy for each extra hp if your using a carburettor.
2. Rated boost for boost, with no intercooler, there is little difference between turbo and a postive displacement blower. On a non-cross flow six, there is so much space for a blower or a turbo, so you can't go wrong.
3. Fuel supply for turbos needs more attention. An EFI turbo will give more power with less fuel than a GMC 4/71 with a Holley. A blow through turbo will suffer delivery problems when the boost goes up.
4. A centrifugal blower will always be harder to get the most out of, but is one of the easier conversions around.
Whenever I consider a turbo or a supercharger, I ask myself, will it take 12 pounds of boost. 12 pounds is the stock hp, times 1.65 in most cases.
As a teen, I studied both. Hot Rod did some great testing back in the 80's. Take one 300 hp 350 V8. Add a 6/71 blower at 12 psi , and get an awesome 490 HP. A Megacharger, less, a TO4, about the same. But the Rootes blower will suck a lot more gas.
When I see stock belt drives like this on Tempos, Topaz, Taurus 2.3/2.5 I4's which our cars share bits with, I'm thinking a 400 buck Ogura supercharger running 7 pounds of boost would make a great replacement for an air pump or power steering unit!
Or a Holley 1949 air cleaner mouth for three Holley 1949's on a six.
People rip SC12 and SC14 blowers out of 1988 to 2001 Toyotas, and they bolt on an on demand 25 to 35% with just the flick of a fan clutch. Hello, 25 to 60 hp on the swithch, dudes!
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Anonymous
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BTW, by "disagreeing" with Slade, I meant that choosing between a blower and a turbo is not like choosing between coke and pepsi. It's not "six of one, half a dozen of the other". They are very different animals.
Yes, I agree that HRM is not exactly an unbiased source. In fact, IIRC the magazine pokes fun at itself in the article by acknowledging that they were biased towards the traditional roots blower, and admit that they were astonished to discover how versatile is the turbo.
X, I agree with most of what you wrote, but would add some clarifications...
1. Agreed. Dollar for dollar, turbos are easier. But turbos are also far more versatile at producing low-RPM boost than traditional blowers. Screw-types can be as good as most turbos, but they are rare and pricey. I don't think you'll see them on eBay for under 50 bucks!
2. There really isn't any such thing as comparing "boost for boost" except at high-RPM WOT (and how much time do you spend there?). Under any other conditions (see chart above) the "area under the curve" is radically different between them, even though these three devices all make similar peak boost.
3. Fuel/air ratio is critical for ANY boosted engine. Lean any of them out and you are asking for trouble. And we're talking carb'd Ford sixes here, not EFI motors...
At the modest boost practical on a low budget I-6, getting enough fuel into the engine, blow or suck, isn't any real challenge. There is a Yahoo Blow-Thru group for DIY, low budget efforts. You can learn lots there, but the list "owner", Dick Datson, is a control freak. Disagree with him and you'll find yourself banned. It's happened to me 3 times... 
4. I have met very few individuals who were happy with centrifugals in other than full-race applications. A quick glance at the chart above tells the story. Their boost is linear with RPM -- you have to spin the motor to get boost. Not very stop light friendly! OTOH, the tiny turbo in my wife's Golf TDi makes usable boost from about 1200 RPMs, and is at full boost (13 psi of boost) at 1700 RPM. Full torque from 1700 RPMs to fuel cut off at 4600 RPMs. That little 1.9l drives like a small V-8!
Yes, I agree that HRM is not exactly an unbiased source. In fact, IIRC the magazine pokes fun at itself in the article by acknowledging that they were biased towards the traditional roots blower, and admit that they were astonished to discover how versatile is the turbo.
X, I agree with most of what you wrote, but would add some clarifications...
1. Agreed. Dollar for dollar, turbos are easier. But turbos are also far more versatile at producing low-RPM boost than traditional blowers. Screw-types can be as good as most turbos, but they are rare and pricey. I don't think you'll see them on eBay for under 50 bucks!
2. There really isn't any such thing as comparing "boost for boost" except at high-RPM WOT (and how much time do you spend there?). Under any other conditions (see chart above) the "area under the curve" is radically different between them, even though these three devices all make similar peak boost.
3. Fuel/air ratio is critical for ANY boosted engine. Lean any of them out and you are asking for trouble. And we're talking carb'd Ford sixes here, not EFI motors...
At the modest boost practical on a low budget I-6, getting enough fuel into the engine, blow or suck, isn't any real challenge. There is a Yahoo Blow-Thru group for DIY, low budget efforts. You can learn lots there, but the list "owner", Dick Datson, is a control freak. Disagree with him and you'll find yourself banned. It's happened to me 3 times... 4. I have met very few individuals who were happy with centrifugals in other than full-race applications. A quick glance at the chart above tells the story. Their boost is linear with RPM -- you have to spin the motor to get boost. Not very stop light friendly! OTOH, the tiny turbo in my wife's Golf TDi makes usable boost from about 1200 RPMs, and is at full boost (13 psi of boost) at 1700 RPM. Full torque from 1700 RPMs to fuel cut off at 4600 RPMs. That little 1.9l drives like a small V-8!
Ever bought something on sale cheap, and then discovered it won't fit in your vehicle, come time to bring it home?
One of the things missing from this thread is a realistic appraisal of what fits in an early Mustang/Falcon engine bay.
I perceive almost insurmountable space issues with a Roots style blower, if you want a basically standard layout. I have also seen a turbo crossflow in a roundbody that trapped so much heat the owner had to paint the engine bay in heatproof paint and louvre the bonnet. Eventually, it holed one of the rear pistons.
Adam.
p.s. Stan - did you exact revenge on the control freak by practising touch-and-go manoevres over his property?
One of the things missing from this thread is a realistic appraisal of what fits in an early Mustang/Falcon engine bay.
I perceive almost insurmountable space issues with a Roots style blower, if you want a basically standard layout. I have also seen a turbo crossflow in a roundbody that trapped so much heat the owner had to paint the engine bay in heatproof paint and louvre the bonnet. Eventually, it holed one of the rear pistons.
Adam.
p.s. Stan - did you exact revenge on the control freak by practising touch-and-go manoevres over his property?
It's all good, Stan!
Ve vill not be using the
-er on this site!
I love the little Ogura super chargers. When something allows you to use dual out headers, and only requires the stock York A/C hanger to make it work, plus about 2000 Aussie dollars to make a 35% power boost, then it looks like a great option.
I wish we had independant auditors. How about an all recipts challange for invoiced dollars per hp? Lowest dollars for highest hp wins.
(Something tells me, you'd win :roll: )
Ve vill not be using the
I love the little Ogura super chargers. When something allows you to use dual out headers, and only requires the stock York A/C hanger to make it work, plus about 2000 Aussie dollars to make a 35% power boost, then it looks like a great option.
I wish we had independant auditors. How about an all recipts challange for invoiced dollars per hp? Lowest dollars for highest hp wins.
(Something tells me, you'd win :roll: )
Like I said...you're going to get opinions.
Boost for Boost, if a SC makes 4psi at 2500RPM and a Turbo makes 4psi at 2500, the power is going to be same except for some small changes in back pressure and resistance from the belt (depending on the induction type).
My problem with magazines is they don't always give unbiased opinions. Usually the article is paid for by an advertiser trying to sell something.
Did they take time to size the pulleys to make the supers geared better to come in early or late?
Things like that can really make a difference.
Boost is Boost.
Personally I like the turbos. I like not having to wonder what RPM I'm at and wonder if I'm going to get enough boost.
Slade
Boost for Boost, if a SC makes 4psi at 2500RPM and a Turbo makes 4psi at 2500, the power is going to be same except for some small changes in back pressure and resistance from the belt (depending on the induction type).
My problem with magazines is they don't always give unbiased opinions. Usually the article is paid for by an advertiser trying to sell something.
Did they take time to size the pulleys to make the supers geared better to come in early or late?
Things like that can really make a difference.
Boost is Boost.
Personally I like the turbos. I like not having to wonder what RPM I'm at and wonder if I'm going to get enough boost.
Slade
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Anonymous
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CobraSix":1e9lx9l5 said:
Not all boost is equal Slade. Discharge air temperatures based on compressor efficiencies is a big factor. And of course, lb/min flow is even more important that the psi level.
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Anonymous
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What in God's green earth do you guys do all day?
I dig holes in roads, measure small amplitude bumps with electronics, and write technical papers on retro-reflectivity. The others do things like picking up foriegn objects from air ports ( 
), fix historical houses, and maintain tin American Stallions by stitching Aussie heads and turbos on them.
Sick bunch...
), fix historical houses, and maintain tin American Stallions by stitching Aussie heads and turbos on them.Sick bunch...
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Anonymous
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xtaxi":33t8oqwm said:
: No it won't.Dan
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Anonymous
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Sorry, Dan, but UpsideDownTaxi is correct. It has long been known that pressurised carbs have fuel distribution problems at fairly modest boost levels. Remember, a carb does not understand pressure. It supplies fuel by creating a pressure drop across a venturi. If the carb sees a 2 PSI pressure drop across the venturi, it will supply that much fuel whether you are at 0 or 20 pounds of boost. This can cause the engine to lean out at high boost, and can lead to fuel distribution problems as well. That's why blow-thru carbs are generally held to about 20 psi boost max.import killer":b5kz5li7 said:
Yet another reason to go draw-thru...!
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Anonymous
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Slade,
While it is true that carbs can be modified to make them more boost-friendly, ultimately they cannot overcome physics. Here's the rub. A venturi is a velocity dependent device. The faster the air moves through it the greater the pressure drop. However, an engine's flow characteristics restrict the velocity of the incoming area to a fairly stable 250 ft/sec or so. That velocity does not change with an increase in boost. However, as boost goes up the mass flow rate (the weight of the air entering the engine) does go up. And as we all know, air-fuel ratio is mass dependent. So what happens is that the mass of air goes up as the boost increases, but the fuel does not, so the engine leans out.
Now, as I said, carbs can be made more boost friendly. In other words, with careful tuning you can get them to maintain a reasonable fuel/air ratio from no boost to some reasonable boost level, usually about 20 psi max. But it can be a real pain to make consistently happen, so most carb'd blow-thru apps stick to relatively low boost levels.
Off to the race track. Back Sunday!
While it is true that carbs can be modified to make them more boost-friendly, ultimately they cannot overcome physics. Here's the rub. A venturi is a velocity dependent device. The faster the air moves through it the greater the pressure drop. However, an engine's flow characteristics restrict the velocity of the incoming area to a fairly stable 250 ft/sec or so. That velocity does not change with an increase in boost. However, as boost goes up the mass flow rate (the weight of the air entering the engine) does go up. And as we all know, air-fuel ratio is mass dependent. So what happens is that the mass of air goes up as the boost increases, but the fuel does not, so the engine leans out.
Now, as I said, carbs can be made more boost friendly. In other words, with careful tuning you can get them to maintain a reasonable fuel/air ratio from no boost to some reasonable boost level, usually about 20 psi max. But it can be a real pain to make consistently happen, so most carb'd blow-thru apps stick to relatively low boost levels.
Off to the race track. Back Sunday!
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Anonymous
Guest
what if your running really rich to begin with would it be fine then....maybe i dont have to fix my jet then 
would it be fine then....maybe i dont have to fix my jet then
What follows is my ideas on it, from stealing everyone elses ove the last 35 years.
1. The Key to any carb turbo is to never, EVER run it out of fuel under boost. If you design it for power, forget ever getting any fuel economy. A 250 cube 300 hp turbo sucks as much gas as a 300 hp big block 455, and when just ambling about, if its jetted only for power, it will use almost as much gas!
2. If you want it to have fuel economy, then you must lean out the fuel delivery via small primaries or some progressive system when cruising on the highway. A good example would be having a Holley 390 cfm carb with small primary jets, and a huge secondary jettiong block. Or a couple of 32/36 or 5200 Holley Weber carbs on a log head. Under cruise, it is lean and sits on lean primary jets. When the hammer goes down, the throttle opens and the richer jets are exposed.
The key to making a blow through work at 20 psi is simple. You rip out the floats, cover it with a letter box, and then figure out a way to allow it to be enrichened under boost. The answer to enrichement is to have an fuel control valve or ratched operated Adjusta Jet. You take a leaf out of the EFI guys book and have it run off a MAP sensor and an Idle Control valve.
The draw through 231 Turbo Buicks worked because the carb ran lean under little boost, then rich as heck when the throttles opened. The had small primaries, and H-U-G-E secondaries. The jetting at wide open throttle on a 301 Turbo Firebird was richer than any 455 Qjet ever was. Even at 20 psi, though, the metering goes haywire, because the air flow developes eddies the venturis just cant cope with.
Lotus solved part of the problem by modulating boost (toning it down under loads) and by having a special bonnet which fitted over the Twin Webers in the Esprit Turbos, or the single SU in the Mini Metro Turbo. Alfa Romeos wicked TurboDelta GTV 2000's ran a similar air flow meter which richened up the carb under boost. It did it by pushing the float level up as boost increased.
Back to the future.
1. The Key to any carb turbo is to never, EVER run it out of fuel under boost. If you design it for power, forget ever getting any fuel economy. A 250 cube 300 hp turbo sucks as much gas as a 300 hp big block 455, and when just ambling about, if its jetted only for power, it will use almost as much gas!
2. If you want it to have fuel economy, then you must lean out the fuel delivery via small primaries or some progressive system when cruising on the highway. A good example would be having a Holley 390 cfm carb with small primary jets, and a huge secondary jettiong block. Or a couple of 32/36 or 5200 Holley Weber carbs on a log head. Under cruise, it is lean and sits on lean primary jets. When the hammer goes down, the throttle opens and the richer jets are exposed.
The key to making a blow through work at 20 psi is simple. You rip out the floats, cover it with a letter box, and then figure out a way to allow it to be enrichened under boost. The answer to enrichement is to have an fuel control valve or ratched operated Adjusta Jet. You take a leaf out of the EFI guys book and have it run off a MAP sensor and an Idle Control valve.
The draw through 231 Turbo Buicks worked because the carb ran lean under little boost, then rich as heck when the throttles opened. The had small primaries, and H-U-G-E secondaries. The jetting at wide open throttle on a 301 Turbo Firebird was richer than any 455 Qjet ever was. Even at 20 psi, though, the metering goes haywire, because the air flow developes eddies the venturis just cant cope with.
Lotus solved part of the problem by modulating boost (toning it down under loads) and by having a special bonnet which fitted over the Twin Webers in the Esprit Turbos, or the single SU in the Mini Metro Turbo. Alfa Romeos wicked TurboDelta GTV 2000's ran a similar air flow meter which richened up the carb under boost. It did it by pushing the float level up as boost increased.
Back to the future.
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Anonymous
Guest
54Ford":3q2wqw9b said:Sorry, Dan, but UpsideDownTaxi is correct. It has long been known that pressurised carbs have fuel distribution problems at fairly modest boost levels. Remember, a carb does not understand pressure. It supplies fuel by creating a pressure drop across a venturi. If the carb sees a 2 PSI pressure drop across the venturi, it will supply that much fuel whether you are at 0 or 20 pounds of boost. This can cause the engine to lean out at high boost, and can lead to fuel distribution problems as well. That's why blow-thru carbs are generally held to about 20 psi boost max.import killer":3q2wqw9b said:
Yet another reason to go draw-thru...!
Has it long been known or long been thought that carbs are no good with turbos? Everyone always told me fuel injection is the only way to go with turbos and carbs sucked with them. I thought they where probably right untill I looked into it and tried it for myself. I am finding out now that most of the time it is the other way around. I have done very little work to my carb and fuel pump to run with boost and it performs perfectly. I am running very small jets and stock PVCRs and I can watch the A/F ratio on my wide band stay right where I need it to be. A simple jet change is all it takes to change the A/F if it is off. I can show you a Mustang with a turbo blowthrough that puts down 1200 hp to the ground and runs 7.80s@180 mph through the 1/4 with a 750 Holley DP and no other means of enrichment other than the carb. It runs somewhere around 26-28 psi!!! It is hard for me to beleive carbs don't do great with turbos anymore. If you ask me blowthrough carbs with turbos is the only way to go. But that is just me.
Dan
