The real advantage of running a turbo??
- Thread starter SHARPIE
- Start date
OLDBULL8
Good Morning Ya'll.
Is this why TYP4 cams are more efficient on turbo engines?
For our engines, maybe the blue is what we need.
Turbocharger Camshafts
Pressure Differential
Unlike a supercharger that is driven directly form the crankshaft, a turbo is driven by exhaust gas velocity. Turbochargers are an exhaust restriction (which raises the exhaust gas pressure), but since they use energy that would otherwise be wasted, they are much more efficient than a belt driven supercharger. Normally when the exhaust valve opens, there is still useable pressure in the cylinder that needs to be dumped so it will not resist the piston trying to go back up the bore. That pressure makes high exhaust gas velocity. With a turbocharged engine, this is the energy that is used to spin the turbine.
With a well matched turbo / engine combo, boost pressure should be higher than exhaust gas pressure at the low side of the power band (near peak torque). As the engine nears peak hp, the pressure differential will get nearer 1:1. At some point the pressures in the intake and exhaust will be equal then crossover making the exhaust a higher pressure than the intake. At peak hp there will usually be more exhaust gas pressure than boost pressure. The ultimate goal is to have as little exhaust backpressure possible for the desired boost.
If the turbocharger is matched well to the engine combination, the camshaft selection will not need to be much different than that of a supercharged engine. The problem is that most factory turbo engines have turbo's that are sized too small and will usually have more back pressure than boost pressure over much of the useable power band. Car manufactures do this in an attempt to reduce turbo lag. When a turbocharger is too small, it will be a bigger restriction in the exhaust, causing more back pressure. A big mistake of turbo owners is to crank the boost up as high as they can thinking they are going faster, but in reality, chances are that they are just killing the efficiency of the turbo and most gains are lost. If you want to run higher boost levels and back pressure is a problem, cam timing can be altered to give respectable power increases for much cheaper than a new turbocharger. Before you go increasing boost and changing cams, remember that the oxygen content into the engine will increase power, not boost pressure. A good flowing head with a good intercooler can make a lot of power without high boost. You may not need more boost to get the power you want.
Valve Overlap
If your one of many factory turbo car owners with a turbo sized too small, there will be higher exhaust pressure than intake, you should see that if both valves are open at the same time, the flow would reverse. Any valve overlap is a no no if you're looking for higher boost with a restrictive turbine housing. The exhaust valve will usually close very close to TDC, but there is will still be more pressure on the cylinder than in the intake. You must allow the piston to travel down the bore until the pressure is equalized. If the cylinder pressure is lower than the intake manifold pressure, no reverse flow will take place. This means that the intake valve needs to open 20-35� ATDC, depending on the amount of boost you're using. Most street turbo's will work well when the valve opens close to 20� ATDC, only when boost gets near 30 psi will you need to delay it as much as 35� ATDC. In low boost applications (under 15 psi or so), opening the valve closer to TDC and maybe keeping the exhaust valve open a little after TDC is a compromise for better throttle response before the boost comes on. As you increase boost, you will need to delay the opening of the intake valve to avoid reversion. You want the intake valve to open as soon as possible, in an ideal situation, the intake valve should open when the pressure in the cylinder is equal to boost pressure. This can cause a little confusion with cam overlap. If the exhaust valve closes before the intake opens, the overlap will be considered negative. If the exhaust valve closed at TDC and the intake opened at 20� ATDC there would be -20� of overlap. In this type situation, pumping losses are quite large, although the turbo will still use less power than a crank driven supercharger.
If you have a well matched turbo for the engine and application, it is a different deal altogether. A well matched turbine housing on the turbo will usually work well with cams with a lobe separation in the 112-114� area. If there is more pressure in the intake than in the exhaust, a camshaft suited for superchargers or nitrous will usually works well. When the exhaust backpressure is lower than the intake, reversion is not a problem, actually just the opposite is a problem. More pressure in the intake can blow fresh intake charge right out the exhaust valve. This can be a serious problem with a turbo motor since the charge will burn in the exhaust raising temperatures of the exhaust valves and turbo. This is also a problem with superchargers, which is why supercharger cam profiles usually work well with turbo's. In this type situation, the power required to turn the turbine is nearly 100% recovered energy that would have normally been dumped out the tailpipe, basically free power. Many will argue that nothing is free and you need pressure to spin the turbine and this must make pumping losses. They are wrong because a turbo is not getting anything for free at all, it is just making the engine more efficient. It is true that there are pumping losses, but on the other hand there are pumping gains as well. If the exhaust back pressure is lower than the intake, the intake pressure makes more force on the intake stroke to help push the piston down. At the same time another piston is on it's exhaust stroke. So the intake pressure is more than canceling out the exhaust pressure. Not free, just more efficient.
Valve Lift
By delaying the opening of the intake, the duration of the cam will be much shorter. A short duration intake works well with a turbo, but the problem is that sufficient lift is hard to get from such a short duration. This is where high ratio rockers can really pay off. A cam for a turbo engine can delay the intake opening by over 40� compared to an cam for a normally aspirated engine. This makes for much less valve lift when the piston is at peak velocity (somewhere near 75� ATDC), any help to get the valve open faster will make large improvements.
Roller Camshafts
Turbo motors place a large flow demand at low valve lifts, and roller cams cannot accelerate the valve opening as fast as a flat tappet. They do catch up and pass a flat tappet after about 20� or so, but up until that point the favor goes toward the flat tappet cam. The area where rollers really help in turbo motors (and supercharged) is cutting frictional losses. Any forced induction engine will need more spring force on the intakes. If you run a lot of boost, you'll need quite a bit more spring force to control the valves. As spring forces gets higher, the life of the cam gets reduced. A roller tappet can withstand more than twice the spring pressure as a flat tappet with no problems. On the exhaust side, it's not the springs that put the loads on the cam lobes. The problem there is that there is still so much cylinder pressure trying to hold that valve closed. This puts tremendous pressure on the exhaust lobes. So when high boost levels are used, consider a roller cam. I would definitely consider a roller cam on engines making more than 20 lbs. of boost.
For our engines, maybe the blue is what we need.
Turbocharger Camshafts
Pressure Differential
Unlike a supercharger that is driven directly form the crankshaft, a turbo is driven by exhaust gas velocity. Turbochargers are an exhaust restriction (which raises the exhaust gas pressure), but since they use energy that would otherwise be wasted, they are much more efficient than a belt driven supercharger. Normally when the exhaust valve opens, there is still useable pressure in the cylinder that needs to be dumped so it will not resist the piston trying to go back up the bore. That pressure makes high exhaust gas velocity. With a turbocharged engine, this is the energy that is used to spin the turbine.
With a well matched turbo / engine combo, boost pressure should be higher than exhaust gas pressure at the low side of the power band (near peak torque). As the engine nears peak hp, the pressure differential will get nearer 1:1. At some point the pressures in the intake and exhaust will be equal then crossover making the exhaust a higher pressure than the intake. At peak hp there will usually be more exhaust gas pressure than boost pressure. The ultimate goal is to have as little exhaust backpressure possible for the desired boost.
If the turbocharger is matched well to the engine combination, the camshaft selection will not need to be much different than that of a supercharged engine. The problem is that most factory turbo engines have turbo's that are sized too small and will usually have more back pressure than boost pressure over much of the useable power band. Car manufactures do this in an attempt to reduce turbo lag. When a turbocharger is too small, it will be a bigger restriction in the exhaust, causing more back pressure. A big mistake of turbo owners is to crank the boost up as high as they can thinking they are going faster, but in reality, chances are that they are just killing the efficiency of the turbo and most gains are lost. If you want to run higher boost levels and back pressure is a problem, cam timing can be altered to give respectable power increases for much cheaper than a new turbocharger. Before you go increasing boost and changing cams, remember that the oxygen content into the engine will increase power, not boost pressure. A good flowing head with a good intercooler can make a lot of power without high boost. You may not need more boost to get the power you want.
Valve Overlap
If your one of many factory turbo car owners with a turbo sized too small, there will be higher exhaust pressure than intake, you should see that if both valves are open at the same time, the flow would reverse. Any valve overlap is a no no if you're looking for higher boost with a restrictive turbine housing. The exhaust valve will usually close very close to TDC, but there is will still be more pressure on the cylinder than in the intake. You must allow the piston to travel down the bore until the pressure is equalized. If the cylinder pressure is lower than the intake manifold pressure, no reverse flow will take place. This means that the intake valve needs to open 20-35� ATDC, depending on the amount of boost you're using. Most street turbo's will work well when the valve opens close to 20� ATDC, only when boost gets near 30 psi will you need to delay it as much as 35� ATDC. In low boost applications (under 15 psi or so), opening the valve closer to TDC and maybe keeping the exhaust valve open a little after TDC is a compromise for better throttle response before the boost comes on. As you increase boost, you will need to delay the opening of the intake valve to avoid reversion. You want the intake valve to open as soon as possible, in an ideal situation, the intake valve should open when the pressure in the cylinder is equal to boost pressure. This can cause a little confusion with cam overlap. If the exhaust valve closes before the intake opens, the overlap will be considered negative. If the exhaust valve closed at TDC and the intake opened at 20� ATDC there would be -20� of overlap. In this type situation, pumping losses are quite large, although the turbo will still use less power than a crank driven supercharger.
If you have a well matched turbo for the engine and application, it is a different deal altogether. A well matched turbine housing on the turbo will usually work well with cams with a lobe separation in the 112-114� area. If there is more pressure in the intake than in the exhaust, a camshaft suited for superchargers or nitrous will usually works well. When the exhaust backpressure is lower than the intake, reversion is not a problem, actually just the opposite is a problem. More pressure in the intake can blow fresh intake charge right out the exhaust valve. This can be a serious problem with a turbo motor since the charge will burn in the exhaust raising temperatures of the exhaust valves and turbo. This is also a problem with superchargers, which is why supercharger cam profiles usually work well with turbo's. In this type situation, the power required to turn the turbine is nearly 100% recovered energy that would have normally been dumped out the tailpipe, basically free power. Many will argue that nothing is free and you need pressure to spin the turbine and this must make pumping losses. They are wrong because a turbo is not getting anything for free at all, it is just making the engine more efficient. It is true that there are pumping losses, but on the other hand there are pumping gains as well. If the exhaust back pressure is lower than the intake, the intake pressure makes more force on the intake stroke to help push the piston down. At the same time another piston is on it's exhaust stroke. So the intake pressure is more than canceling out the exhaust pressure. Not free, just more efficient.
Valve Lift
By delaying the opening of the intake, the duration of the cam will be much shorter. A short duration intake works well with a turbo, but the problem is that sufficient lift is hard to get from such a short duration. This is where high ratio rockers can really pay off. A cam for a turbo engine can delay the intake opening by over 40� compared to an cam for a normally aspirated engine. This makes for much less valve lift when the piston is at peak velocity (somewhere near 75� ATDC), any help to get the valve open faster will make large improvements.
Roller Camshafts
Turbo motors place a large flow demand at low valve lifts, and roller cams cannot accelerate the valve opening as fast as a flat tappet. They do catch up and pass a flat tappet after about 20� or so, but up until that point the favor goes toward the flat tappet cam. The area where rollers really help in turbo motors (and supercharged) is cutting frictional losses. Any forced induction engine will need more spring force on the intakes. If you run a lot of boost, you'll need quite a bit more spring force to control the valves. As spring forces gets higher, the life of the cam gets reduced. A roller tappet can withstand more than twice the spring pressure as a flat tappet with no problems. On the exhaust side, it's not the springs that put the loads on the cam lobes. The problem there is that there is still so much cylinder pressure trying to hold that valve closed. This puts tremendous pressure on the exhaust lobes. So when high boost levels are used, consider a roller cam. I would definitely consider a roller cam on engines making more than 20 lbs. of boost.
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hesutton
The Anti-Anderson
The blue paragraph above is what I've posted about before. Folks using Banks, Hypermax, or ATS turbo's on these IDI's who boost over 12-13 psi are way out of the efficency range of these turbos and aren't making more power. My dyno runs showed this when I put on the Moose injectors. My wastegate was disabled and with the DPS units I would max at 13 psi. With the Moose injectors my boost pegged the 15 psi gauge and I lost 8 or 9 HP. It is also one of the reasons I'm adding an intercooler to my 6.9 as I have Moose fuel coming for it as well.
Heath
Heath
SHARPIE
Full Access Member
Great articles Thanks guys, You should take them and make a sticky...
'94IDITurbo7.3
HAMMER DOWN!
so based on the blue paragraph above it would be "recommended" to have an intercooler even if you are only pushing ~10psi boost max just because the air will be cooler=better efficiency?
FORDF250HDXLT
The life of an Indian is like the wings of the air
yes.even if you have no issues with EGT's.
the internal combustion engine is,lets face it,horribly inefficient.diesel is much better than gas,but most of your fuel goes wasted generating heat rather than the wheels.everything you can do to bring this up,is bound to help.
along with the turbo,an intercooler is on my list.
i need 1 more hp like i need a hole in my head.i need fuel gains to lower my overhead.
it's all worth it.those who typically install intercoolers will use the extra fuel rather than backing off,because they want to continue up the hill without slowing down,or go up them even faster.install an intercooler,and drive the same way,and you should see the FE gain.
Black dawg
Registered User
I wonder if the wastegate being disabled had anything to do with the hp loss? those results have never made sense to me.
Black dawg
Registered User
the thing that surprised me most about my intercooler was how much power it added in the 0-5psi range
hesutton
The Anti-Anderson
Wastegate was disabled on all the dyno pulls I've made with the F250. The reason for the power loss is explained above.
Heath
Dave Barbieri
Full Access Member
As I rebuild the engine on my 85, a turbo is definitely at the top of the list. It's money well spent. The whole purpose of the turbo is to shove more air into the engine, making better use of the fuel that's there. This means my motor runs more efficiently - more boom per drop of diesel and fewer drops needed to do the job. But for me - there's a BIG additional benefit. LESS SMOKE!! Me and my NA truck have received 3 citations from the Texas Air Quality Board. Folks noticed the smoke when I accelerated to get on the freeway or whatever, and called in a complaint. Well, that issue goes away with the addition of the turbo.
More mileage, more power and way less smoke. What's not to like???
I'm using an old ATS system off a 93 that I bought a couple of years ago.
More mileage, more power and way less smoke. What's not to like???
I'm using an old ATS system off a 93 that I bought a couple of years ago.
FORDF250HDXLT
The life of an Indian is like the wings of the air
why don't you turn the fuel down a bit for now Dave? you don't think that black smoke = power do you?
Black dawg
Registered User
Wastegate was disabled on all the dyno pulls I've made with the F250. The reason for the power loss is explained above.
Heath
what I was getting at is 13-15psi is easily attainable with a fully functioning wastegate and that having yours blocked is costing you power. With a too small turbine housing and no way to release some drive pressure, back pressure is going to go through the roof and get worse the harder you push it.
Dave Barbieri
Full Access Member
You got that right!
My truck was living proof that 'rolling coal' was mostly a rolling joke. The overhaul will take care of cylinder sealing issues (blown head gasket and intake valves not seating), fueling (new injectors, rebuilt IP) and other internal upgrades (cam, balancing, destroked pistons). Net result will be a much more efficient motor and much less smoke! 
VStorm
Captain TowHart
Diesel engines do run lean, they detonate by design and are designed to withstand it to improve efficiency. Over-boosting your turbo just leans the mixture out even more and if you don't have the fuel to enrichen the mixture to optimal, you will lose power. On a N/A engine that's smoking excessively, turning down the pump is the fastest way to get your engine legal again and you will definitely get better mileage while you eliminate smoke.
The pre-Powerstroke Ford IDI turbos were not designed to boost the sea level power significantly although they do make more. They were designed to bring the power on at a lower RPM and to maintain their sea level power up to 10,000 ft above sea level improving drivability all around and were a total success in that regard. They did that while maintaining their designed fuel economy as well.
If you have a turbo, then you can increase the boost by adjusting or removing the wastegate and after you do, you can turn up the pump for increased top end power. You can also turn up the low speed torque screw on the pump for some real low speed improvement as well and if you have a factory IDI turbo model, it is possible to double the power output through careful tuning of those three parameters along with adding a methanol injection system.
You can go beyond that with cold air induction and the use of a hood scoop and fan forced intercooling. If you use a good water to air system or hood mounted intercooler with short induction pipes, an electric fan to keep it cool while standing still and methanol injection along with cowl cold air induction, you can boost power without turbo lag. Do that and learn how to tune your pump and waste gate and you can blow the doors off of just about any early Powerstroke that has been chipped. Better use the factory IDI turbo engine though or at least make the dozen changes in durability that the factory spec'd or you'll leave engine parts all over the ground along with those PS doors.
I'll take the IDI turbo over a powerstroke any day. An added bonus for this engine is you can burn waste vegetable oil, motor oil, trans oil, etc. and as long as you pre heat it to at least 200 degrees F, there will be no coking of the engine and no reliability issues as the IDI uses a pre-combustion chamber along with higher compression ratios to eliminate cold oil contamination of the cylinder walls and piston rings. All you need to do to any waste oil is to filter it through a couple of cheap rolls of single ply toilet paper, using dual Franz filters in series which will also remove any water from the oil and polish it into premium fuel. Then, pre heat the oil using engine coolant to get it above 125 degrees F before the IP and finally small resistance heaters at the injector lines to bring it to at least 160 degrees F and preferably 200 degrees F to avoid any unburned fuel problems.
Using the larger NTZ filter housing with a roll of paper similar to cheap paper towling as a bypass oil filter and full synthetic oil such as Mobil One(most that claim they are, aren't) that is more oil than additive unlike Amzoil will let you run 100,000 miles before an oil change. Yes, it's being done every day with no harmfull effects on the engines. Replace your trans and diff oil with synthetic as well. I like Royal Purple and don't forget to add another cooler and TP filter under the truck for the trans oil. Switch to Peak Final Charge Global coolant and install a cheap cartridge oil filter system to remove the debris from your cooling system and you may never have to change coolant again. Now you have a machine that will run and run with minimal maintenance and very little expense.
Yes, you really will have a doomsday machine that can effectively get 100 or more MPG depending on how far you drive before you switch back to diesel and shut down. That's 100+ MPG on the fuel that you have to pay for. Fill your rear tank with diesel or bio-diesel that you purchase, your front tank with waste oil that you beg from auto shops and mix it with 15% gasoline and filter it with the Franz fuel polisher and your 100 gallon tank in the bed can hold all the waste vegetable oil that you can collect while traveling around also polished and heated while you drive.
Then, when the do-do really hits the fan and nobody is frying potatoes any more, build a biomass generator out of junk, install it in the bed and burn fallen trees and other garbage from the side of the road. I am a retired, fully licensed Aviation Master Technician and all of these mods have either been done by myself or witnessed by me over the years and I can attest to their authenticity. The 7.3 IDI turbo and the 5.9 12 valve Cummins are both old school diesels and either one can make upwards of 1,000 HP if done properly and carefully. If you don't believe me, start hanging out at tractor pulls and see for yourself. Yes, it is more complicated than I have written quickly here but I assure you, entirely possible. Gentlemen, Long Live the 7.3 IDI(and it's glorious V8 sound)! I am a FREE man living in the USA and I dare anyone to try and stop me from driving mine!
The pre-Powerstroke Ford IDI turbos were not designed to boost the sea level power significantly although they do make more. They were designed to bring the power on at a lower RPM and to maintain their sea level power up to 10,000 ft above sea level improving drivability all around and were a total success in that regard. They did that while maintaining their designed fuel economy as well.
If you have a turbo, then you can increase the boost by adjusting or removing the wastegate and after you do, you can turn up the pump for increased top end power. You can also turn up the low speed torque screw on the pump for some real low speed improvement as well and if you have a factory IDI turbo model, it is possible to double the power output through careful tuning of those three parameters along with adding a methanol injection system.
You can go beyond that with cold air induction and the use of a hood scoop and fan forced intercooling. If you use a good water to air system or hood mounted intercooler with short induction pipes, an electric fan to keep it cool while standing still and methanol injection along with cowl cold air induction, you can boost power without turbo lag. Do that and learn how to tune your pump and waste gate and you can blow the doors off of just about any early Powerstroke that has been chipped. Better use the factory IDI turbo engine though or at least make the dozen changes in durability that the factory spec'd or you'll leave engine parts all over the ground along with those PS doors.
I'll take the IDI turbo over a powerstroke any day. An added bonus for this engine is you can burn waste vegetable oil, motor oil, trans oil, etc. and as long as you pre heat it to at least 200 degrees F, there will be no coking of the engine and no reliability issues as the IDI uses a pre-combustion chamber along with higher compression ratios to eliminate cold oil contamination of the cylinder walls and piston rings. All you need to do to any waste oil is to filter it through a couple of cheap rolls of single ply toilet paper, using dual Franz filters in series which will also remove any water from the oil and polish it into premium fuel. Then, pre heat the oil using engine coolant to get it above 125 degrees F before the IP and finally small resistance heaters at the injector lines to bring it to at least 160 degrees F and preferably 200 degrees F to avoid any unburned fuel problems.
Using the larger NTZ filter housing with a roll of paper similar to cheap paper towling as a bypass oil filter and full synthetic oil such as Mobil One(most that claim they are, aren't) that is more oil than additive unlike Amzoil will let you run 100,000 miles before an oil change. Yes, it's being done every day with no harmfull effects on the engines. Replace your trans and diff oil with synthetic as well. I like Royal Purple and don't forget to add another cooler and TP filter under the truck for the trans oil. Switch to Peak Final Charge Global coolant and install a cheap cartridge oil filter system to remove the debris from your cooling system and you may never have to change coolant again. Now you have a machine that will run and run with minimal maintenance and very little expense.
Yes, you really will have a doomsday machine that can effectively get 100 or more MPG depending on how far you drive before you switch back to diesel and shut down. That's 100+ MPG on the fuel that you have to pay for. Fill your rear tank with diesel or bio-diesel that you purchase, your front tank with waste oil that you beg from auto shops and mix it with 15% gasoline and filter it with the Franz fuel polisher and your 100 gallon tank in the bed can hold all the waste vegetable oil that you can collect while traveling around also polished and heated while you drive.
Then, when the do-do really hits the fan and nobody is frying potatoes any more, build a biomass generator out of junk, install it in the bed and burn fallen trees and other garbage from the side of the road. I am a retired, fully licensed Aviation Master Technician and all of these mods have either been done by myself or witnessed by me over the years and I can attest to their authenticity. The 7.3 IDI turbo and the 5.9 12 valve Cummins are both old school diesels and either one can make upwards of 1,000 HP if done properly and carefully. If you don't believe me, start hanging out at tractor pulls and see for yourself. Yes, it is more complicated than I have written quickly here but I assure you, entirely possible. Gentlemen, Long Live the 7.3 IDI(and it's glorious V8 sound)! I am a FREE man living in the USA and I dare anyone to try and stop me from driving mine!
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Not all pumps had the torque screw.
Like what, heavier wrist pins? (On EDIT: Ron can show pictures for what this causes.)
Oil can be burned at room temperature and lower.
Why not just use a centrifuge?
Why not just use a coolant filter, they're cheap and some even are preloaded with SCAs.
Don't bother bringing up an A&P license, you're not the only one here...
And with the IDI it'll destroy the block, Just as Ken and Hypermax found out.
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