ARP Custom 6.9 Head Studs +625 Alloy Group Buy
#31
06-19-2014, 09:10 AM
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In all honesty, I think you should just go for a DI system like a 3208 Cat and swap that into your Ford.
It is well known that DI is a better combustion process. Hence why all Heavy-Duty engines used it. And why Common Rail uses it.
As to why IDI was invented, I'm not sure. I'm guessing to lower emissions because of a more complete burning of fuel.
But if you want to do what you're doing,,, go for it. Do something no one else ever has tried... Or ever will.
It is well known that DI is a better combustion process. Hence why all Heavy-Duty engines used it. And why Common Rail uses it.
As to why IDI was invented, I'm not sure. I'm guessing to lower emissions because of a more complete burning of fuel.
But if you want to do what you're doing,,, go for it. Do something no one else ever has tried... Or ever will.
#33
06-19-2014, 10:31 AM
In all honesty, I think you should just go for a DI system like a 3208 Cat and swap that into your Ford.
It is well known that DI is a better combustion process. Hence why all Heavy-Duty engines used it. And why Common Rail uses it.
As to why IDI was invented, I'm not sure. I'm guessing to lower emissions because of a more complete burning of fuel.
But if you want to do what you're doing,,, go for it. Do something no one else ever has tried... Or ever will.
It is well known that DI is a better combustion process. Hence why all Heavy-Duty engines used it. And why Common Rail uses it.
As to why IDI was invented, I'm not sure. I'm guessing to lower emissions because of a more complete burning of fuel.
But if you want to do what you're doing,,, go for it. Do something no one else ever has tried... Or ever will.
And from a combustion standpoint, DI is actually not better, its construed that way because the manufacturers use it. IDI is actually a far superior way to combust a light oil like diesel, you get a faster total injection event, a more complete burn, and better Emissions...If you can keep the heat in the pre-chamber... And therein lies the problem with IDI, and the reason MB stopped using it in the early 2000's... It soaks too much heat into the cooling system...However, the combustion characteristics are superior to DI. The reason for the wide use of DI is because its easier to manufacture, and with current computer controlled commonrail tech, you can get closer-to-IDI-like-combustion from multiple injection events, but you don't get the heat loss of IDI... I would argue however, that an engine like the 3208 that is old and basically a throwaway diesel, its not better in the combustion department than a 6.9 or 7.3....
As for the rest, why build a 7.3psd either?? Its limited by a crappy (For performance anyway) injection system, and wont survive much past 500whp without a $3000 set of rods... Same with the duramax.... So why build either engine when you can have a 5.9 that will hold 800-1000 on a stock bottom end right??
The Attitude I will never get in the IDI realm, is why it is ok to build up every other engine in history, but when it comes to the IDI "Nope, Cant do that, impossible, no way in hell, weren't meant to go fast, keep'r slow and steady".... Yeah, and Im gonna drop a Small Block Chevy in my ford hot rod while Im at it.
Every other diesel has been taken to its limit, but how dare we find out where an IDI's limit is.... We would rather romanticize and pass fake stories around like Block's Flexing and popping out freeze plugs....
#34
06-19-2014, 10:36 AM
I shoot them another call today, and see if I can get the number. I don't think it will be too far off from there Tom.
#36
06-19-2014, 10:55 PM
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The 3208 is worse of a boat anchor than the IDI...
And from a combustion standpoint, DI is actually not better, its construed that way because the manufacturers use it. IDI is actually a far superior way to combust a light oil like diesel, you get a faster total injection event, a more complete burn, and better Emissions...If you can keep the heat in the pre-chamber... And therein lies the problem with IDI, and the reason MB stopped using it in the early 2000's... It soaks too much heat into the cooling system...However, the combustion characteristics are superior to DI. The reason for the wide use of DI is because its easier to manufacture, and with current computer controlled commonrail tech, you can get closer-to-IDI-like-combustion from multiple injection events, but you don't get the heat loss of IDI... I would argue however, that an engine like the 3208 that is old and basically a throwaway diesel, its not better in the combustion department than a 6.9 or 7.3....
As for the rest, why build a 7.3psd either?? Its limited by a crappy (For performance anyway) injection system, and wont survive much past 500whp without a $3000 set of rods... Same with the duramax.... So why build either engine when you can have a 5.9 that will hold 800-1000 on a stock bottom end right??
The Attitude I will never get in the IDI realm, is why it is ok to build up every other engine in history, but when it comes to the IDI "Nope, Cant do that, impossible, no way in hell, weren't meant to go fast, keep'r slow and steady".... Yeah, and Im gonna drop a Small Block Chevy in my ford hot rod while Im at it.
Every other diesel has been taken to its limit, but how dare we find out where an IDI's limit is.... We would rather romanticize and pass fake stories around like Block's Flexing and popping out freeze plugs....
And from a combustion standpoint, DI is actually not better, its construed that way because the manufacturers use it. IDI is actually a far superior way to combust a light oil like diesel, you get a faster total injection event, a more complete burn, and better Emissions...If you can keep the heat in the pre-chamber... And therein lies the problem with IDI, and the reason MB stopped using it in the early 2000's... It soaks too much heat into the cooling system...However, the combustion characteristics are superior to DI. The reason for the wide use of DI is because its easier to manufacture, and with current computer controlled commonrail tech, you can get closer-to-IDI-like-combustion from multiple injection events, but you don't get the heat loss of IDI... I would argue however, that an engine like the 3208 that is old and basically a throwaway diesel, its not better in the combustion department than a 6.9 or 7.3....
As for the rest, why build a 7.3psd either?? Its limited by a crappy (For performance anyway) injection system, and wont survive much past 500whp without a $3000 set of rods... Same with the duramax.... So why build either engine when you can have a 5.9 that will hold 800-1000 on a stock bottom end right??
The Attitude I will never get in the IDI realm, is why it is ok to build up every other engine in history, but when it comes to the IDI "Nope, Cant do that, impossible, no way in hell, weren't meant to go fast, keep'r slow and steady".... Yeah, and Im gonna drop a Small Block Chevy in my ford hot rod while Im at it.
Every other diesel has been taken to its limit, but how dare we find out where an IDI's limit is.... We would rather romanticize and pass fake stories around like Block's Flexing and popping out freeze plugs....
In my personal point of view, multiple injection events just wastes fuel and shortens injector life (Common Rail & HEUI). I mean are people really that noise and emissions sensitive they need a super-quiet and clean diesel? just put some noise damping foam padding in the cab and you should be ready to rock. As for emissions, proper timing can affect that.
The 3208 is not a bad engine, I've been around them before. Just not enough fuel to them. The 5.7 Olds is the real boat anchor.
Not to mention I've heard horror stories of precups cracking past the firering and leaking compression gasses into the coolant on the Chevrolet diesels. I'm guessing IDI was invented for Emissions at the expense of fuel economy.
And there's nothing wrong with 5.9s, DT466s, 7.3 PSDs. They are capable of massive power output. Even though I know you can't compare a DT466 to an IDI or 12v just because the block is just that much stronger.
And the part about IDI blocks flexing and popping freeze plugs out.. Wheres the proof?
Onto the point, if you can get 400hp to the wheels on the IDI reliability without blowing stupid headgaskets it will change the way they are looked at forever. Keep it up.
#37
06-20-2014, 09:45 AM
If DI is easier to produce, than why did all diesel cars use IDI?
Lower injection pressures meant quieter running engines...The ability to use big nozzles and lower pop pressures meant a smooth running diesel without sacrificing fuel mileage. When somebody buys a car, they are way more prone to judge their purchase on the comfort of the ride, and a rattlebox would have sold less cars
In my personal point of view, multiple injection events just wastes fuel and shortens injector life (Common Rail & HEUI). I mean are people really that noise and emissions sensitive they need a super-quiet and clean diesel? just put some noise damping foam padding in the cab and you should be ready to rock. As for emissions, proper timing can affect that.
Yes, people are that sensitive, ever sat next to an Idling 12v with your window open in traffic? Now imagine every diesel on the road like that...
The 3208 is not a bad engine, I've been around them before. Just not enough fuel to them. The 5.7 Olds is the real boat anchor.
There is definitely a scale to the term "boat anchor", but the 3208 is just a big gutless, smelly 150hp 10.4L N/A diesel (Cept for the turbo models obviously). I really don't mean to hate on the 3208, your right, its not a bad engine, I would put it into the same classification as the IDI. Its a little little bigger, which could make for sizing issues, but if somebody wanted to push that platform, Id be completely behind it... But I wouldn't ditch the IDI for an engine with the same sort of unknowns...
Not to mention I've heard horror stories of precups cracking past the firering and leaking compression gasses into the coolant on the Chevrolet diesels. I'm guessing IDI was invented for Emissions at the expense of fuel economy.
Horror stories? Like 2 in a million? plenty of DI horror stories out there as well
And there's nothing wrong with 5.9s, DT466s, 7.3 PSDs. They are capable of massive power output. Even though I know you can't compare a DT466 to an IDI or 12v just because the block is just that much stronger.
That's one of the big points I always make though, Is the 5.9 was nothing for diesel performance (outside of the pulling ring, same with the DT466) before the PSD came around, and just so started coming with the P-pump then as well. The 7.3 psd, while has been frivolously pushed with the stock forged rods (which are twins to IDIT rods, just wider at the crank), but the general consensus by people that break them, is they are good to about 550whp tops. That means a set of $3000-$5000 rods, and then the block becomes an issue. At what point does the 7.3PSD not be worth building up? Yes, I think weve found the limit of what a 6.9 can do with standard head studs, and the whole point of this thread is to get something better to the people who feel they might wanna push the 6.9 further than what the stock studs are good for... We still don't know where the physical limit of the IDI is beyond bolt on parts. I will make this point in comparison to the 7.3psd (Or even worse, the 6.0), I build my IDI (Documented fully in my thread) with brand new everything, and all my top shelf parts, with a new turbo for $7000. Now think about a 7.3PSD build from the bottom up with a new turbo and 190/100 sticks (basically the equivalent to my IDI), for the same amount of power, I doubt you could build a 7.3psd for the same price. The only limiter to my IDI from busting into the easy mid-400's is the head studs.
And the part about IDI blocks flexing and popping freeze plugs out.. Wheres the proof?
Its the old hypermax tale. Nobody seems to know any details on the truck, not even hypermax, and yet they all seem to know "in detail" how it flexed the block so hard, that the freeze plugs popped out and it had to have rubber freeze plugs. Im sorry, but any engine at that level, even a PSD, is going to have a filled block to even survive getting off the line before Splitting not flexing... It also wasn't a 6.9, the heads would have never stayed on (Though could have had copper gaskets and no coolant, which is most likely)... Point is, there is a lot of junk info flowing around the IDI circle, and the Idea is to prove it right or wrong so we can build a better engine.
Onto the point, if you can get 400hp to the wheels on the IDI reliability without blowing stupid headgaskets it will change the way they are looked at forever. Keep it up.
Lower injection pressures meant quieter running engines...The ability to use big nozzles and lower pop pressures meant a smooth running diesel without sacrificing fuel mileage. When somebody buys a car, they are way more prone to judge their purchase on the comfort of the ride, and a rattlebox would have sold less cars
In my personal point of view, multiple injection events just wastes fuel and shortens injector life (Common Rail & HEUI). I mean are people really that noise and emissions sensitive they need a super-quiet and clean diesel? just put some noise damping foam padding in the cab and you should be ready to rock. As for emissions, proper timing can affect that.
Yes, people are that sensitive, ever sat next to an Idling 12v with your window open in traffic? Now imagine every diesel on the road like that...
The 3208 is not a bad engine, I've been around them before. Just not enough fuel to them. The 5.7 Olds is the real boat anchor.
There is definitely a scale to the term "boat anchor", but the 3208 is just a big gutless, smelly 150hp 10.4L N/A diesel (Cept for the turbo models obviously). I really don't mean to hate on the 3208, your right, its not a bad engine, I would put it into the same classification as the IDI. Its a little little bigger, which could make for sizing issues, but if somebody wanted to push that platform, Id be completely behind it... But I wouldn't ditch the IDI for an engine with the same sort of unknowns...
Not to mention I've heard horror stories of precups cracking past the firering and leaking compression gasses into the coolant on the Chevrolet diesels. I'm guessing IDI was invented for Emissions at the expense of fuel economy.
Horror stories? Like 2 in a million? plenty of DI horror stories out there as well
And there's nothing wrong with 5.9s, DT466s, 7.3 PSDs. They are capable of massive power output. Even though I know you can't compare a DT466 to an IDI or 12v just because the block is just that much stronger.
That's one of the big points I always make though, Is the 5.9 was nothing for diesel performance (outside of the pulling ring, same with the DT466) before the PSD came around, and just so started coming with the P-pump then as well. The 7.3 psd, while has been frivolously pushed with the stock forged rods (which are twins to IDIT rods, just wider at the crank), but the general consensus by people that break them, is they are good to about 550whp tops. That means a set of $3000-$5000 rods, and then the block becomes an issue. At what point does the 7.3PSD not be worth building up? Yes, I think weve found the limit of what a 6.9 can do with standard head studs, and the whole point of this thread is to get something better to the people who feel they might wanna push the 6.9 further than what the stock studs are good for... We still don't know where the physical limit of the IDI is beyond bolt on parts. I will make this point in comparison to the 7.3psd (Or even worse, the 6.0), I build my IDI (Documented fully in my thread) with brand new everything, and all my top shelf parts, with a new turbo for $7000. Now think about a 7.3PSD build from the bottom up with a new turbo and 190/100 sticks (basically the equivalent to my IDI), for the same amount of power, I doubt you could build a 7.3psd for the same price. The only limiter to my IDI from busting into the easy mid-400's is the head studs.
And the part about IDI blocks flexing and popping freeze plugs out.. Wheres the proof?
Its the old hypermax tale. Nobody seems to know any details on the truck, not even hypermax, and yet they all seem to know "in detail" how it flexed the block so hard, that the freeze plugs popped out and it had to have rubber freeze plugs. Im sorry, but any engine at that level, even a PSD, is going to have a filled block to even survive getting off the line before Splitting not flexing... It also wasn't a 6.9, the heads would have never stayed on (Though could have had copper gaskets and no coolant, which is most likely)... Point is, there is a lot of junk info flowing around the IDI circle, and the Idea is to prove it right or wrong so we can build a better engine.
Onto the point, if you can get 400hp to the wheels on the IDI reliability without blowing stupid headgaskets it will change the way they are looked at forever. Keep it up.
#38
06-20-2014, 11:19 AM
Ah i missed the fun. But justin, im pretty sure most 1160/3208s are closer to the 225hp range, still anemic, but they are torquey monsters and alot of fun to drive (have a 69 F8000 1160 5+4 straight stacked).
Either way, gaurdian youre asking for proof, wheres the proof that DI is better than IDI? Everyone says that DI is 10% more efficient.... efficient where? IDI makes more hp per cc, more hp per lb of air, how are they more efficient? I agree with racin, the issue with efficiency, is thermal efficiency. The pre-cup sucks way too much heat into the head / coolant. The couple articles i found on IDI were explaining how IDI was going to make DI engines obsolete. Perkins used IDIs forever.
Either way, gaurdian youre asking for proof, wheres the proof that DI is better than IDI? Everyone says that DI is 10% more efficient.... efficient where? IDI makes more hp per cc, more hp per lb of air, how are they more efficient? I agree with racin, the issue with efficiency, is thermal efficiency. The pre-cup sucks way too much heat into the head / coolant. The couple articles i found on IDI were explaining how IDI was going to make DI engines obsolete. Perkins used IDIs forever.
#39
06-20-2014, 11:25 AM
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Thanks, and that's the idea.... Fueling is no longer the weak link, Turbos are no longer the weak link, You can shave pistons without melting them, and even run 34psi on a stock IDIT bottom end... People don't see it in real time, but if you look back 3 years and compare what we know now from then, its pretty shocking. If we don't find the end of the road physically, imagine what the next 3 years will bring....
And I don't really see how lower pop pressure makes a quieter running engine. I thought lower makes it louder because there is very little atomization with low pop pressures opposed to higher pop pressures. My 7.3 N/A IDI is louder than my bosses 1999 7.3 Powerstroke (When it used to run). Can you explain that? and yes it is timed correctly. Bone stock engine too.
And believe me, I've driven more Dodge 5.9s than you think. The noise in the cab gives me a headache after a while. The IDI is much smoother when cruising, but at idle, is worse than a PSD. At least mine is.
There are also rumors about larger precup throats making the engine run louder... That is simply not true at all. Precup throat size is for mpg OR Power, chose one. And the Hypermax about busting out freeze plugs is a lie. Trust me. Maybe we should meet up and build a 1200hp IDI and see if It's the truth or a blatant lie.
In the end, trial and error is the only way to prove and disprove these theories. Prehaps tap the block for 1/2 studs and say good bye to HG problems.
#40
06-20-2014, 11:29 AM
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Ah i missed the fun. But justin, im pretty sure most 1160/3208s are closer to the 225hp range, still anemic, but they are torquey monsters and alot of fun to drive (have a 69 F8000 1160 5+4 straight stacked).
Either way, gaurdian youre asking for proof, wheres the proof that DI is better than IDI? Everyone says that DI is 10% more efficient.... efficient where? IDI makes more hp per cc, more hp per lb of air, how are they more efficient? I agree with racin, the issue with efficiency, is thermal efficiency. The pre-cup sucks way too much heat into the head / coolant. The couple articles i found on IDI were explaining how IDI was going to make DI engines obsolete. Perkins used IDIs forever.
Either way, gaurdian youre asking for proof, wheres the proof that DI is better than IDI? Everyone says that DI is 10% more efficient.... efficient where? IDI makes more hp per cc, more hp per lb of air, how are they more efficient? I agree with racin, the issue with efficiency, is thermal efficiency. The pre-cup sucks way too much heat into the head / coolant. The couple articles i found on IDI were explaining how IDI was going to make DI engines obsolete. Perkins used IDIs forever.
And where are those articles? I'm interested. There are several different IDI designs too. The Germans had their own design if I remember correctly.
#41
06-20-2014, 12:22 PM
I've always wondered what is the maximum amount you can shave off our pistons without risk of ring-land damage from heat, Mahle says .015 but I have faith you can go much farther. Say that you want to shave pistons and want that motor go 200k+ miles? I am considering building up my IDI.
And I don't really see how lower pop pressure makes a quieter running engine. I thought lower makes it louder because there is very little atomization with low pop pressures opposed to higher pop pressures. My 7.3 N/A IDI is louder than my bosses 1999 7.3 Powerstroke (When it used to run). Can you explain that? and yes it is timed correctly. Bone stock engine too.
And believe me, I've driven more Dodge 5.9s than you think. The noise in the cab gives me a headache after a while. The IDI is much smoother when cruising, but at idle, is worse than a PSD. At least mine is.
There are also rumors about larger precup throats making the engine run louder... That is simply not true at all. Precup throat size is for mpg OR Power, chose one. And the Hypermax about busting out freeze plugs is a lie. Trust me. Maybe we should meet up and build a 1200hp IDI and see if It's the truth or a blatant lie.
In the end, trial and error is the only way to prove and disprove these theories. Prehaps tap the block for 1/2 studs and say good bye to HG problems.
And I don't really see how lower pop pressure makes a quieter running engine. I thought lower makes it louder because there is very little atomization with low pop pressures opposed to higher pop pressures. My 7.3 N/A IDI is louder than my bosses 1999 7.3 Powerstroke (When it used to run). Can you explain that? and yes it is timed correctly. Bone stock engine too.
And believe me, I've driven more Dodge 5.9s than you think. The noise in the cab gives me a headache after a while. The IDI is much smoother when cruising, but at idle, is worse than a PSD. At least mine is.
There are also rumors about larger precup throats making the engine run louder... That is simply not true at all. Precup throat size is for mpg OR Power, chose one. And the Hypermax about busting out freeze plugs is a lie. Trust me. Maybe we should meet up and build a 1200hp IDI and see if It's the truth or a blatant lie.
In the end, trial and error is the only way to prove and disprove these theories. Prehaps tap the block for 1/2 studs and say good bye to HG problems.
If you had been following the progression of his 6.9 build you would understand why this thread is here for the special studs. Beyond that, you cannot drill a 7/16" tapped hole for 1/2 studs because it does not clean it up. Helicoils and 9/16 studs are also out. I suggest reading smogies build thread.
#43
06-20-2014, 09:07 PM
#44
06-23-2014, 12:53 PM
I've always wondered what is the maximum amount you can shave off our pistons without risk of ring-land damage from heat, Mahle says .015 but I have faith you can go much farther. Say that you want to shave pistons and want that motor go 200k+ miles? I am considering building up my IDI.
The Ring-Lands are steel, and I highly doubt they would be effected at all even if you could shave them enough to get close. The thinnest part of the crown is a little more than 9/16 thick. Ive shaved as much as .080" off the pistons, and my own engine has .050" taken off. The weak spot on the piston is the edge next to the recardo "Chute", too much timing or EGT's and that will be the first part of the piston to go. I personally wont put an IDI that will see more load than stock together without ceramic coated tops, ive seen too many stock pistons melted there. Shaving the piston arguably helps to keep that edge from melting by taking the thin edge away.
And I don't really see how lower pop pressure makes a quieter running engine. I thought lower makes it louder because there is very little atomization with low pop pressures opposed to higher pop pressures. My 7.3 N/A IDI is louder than my bosses 1999 7.3 Powerstroke (When it used to run). Can you explain that? and yes it is timed correctly. Bone stock engine too.
The injector has very little to do with any atomization in an IDI, as soon as the fuel hits the precup/gp, its vaporized. As Mike said, a lower pop pressure makes for a longer injection duration by lowering total injection pressure. The longer injection duration means a more mellow, less violent burn... Less Noise, smoother running. Every stock IDI Ive ever heard is pretty quiet. As for comparison to the PSD, that's because it has split shot injectors, those PSD's were pretty quiet. Compare to a 94.5 PSD for noise, those are damn near as bad as a cummins.
And believe me, I've driven more Dodge 5.9s than you think. The noise in the cab gives me a headache after a while. The IDI is much smoother when cruising, but at idle, is worse than a PSD. At least mine is.
There are also rumors about larger precup throats making the engine run louder... That is simply not true at all. Precup throat size is for mpg OR Power, chose one. And the Hypermax about busting out freeze plugs is a lie. Trust me. Maybe we should meet up and build a 1200hp IDI and see if It's the truth or a blatant lie.
Id disagree about the pre-cups. I don't think they have much effect on anything aside from very small tuning in Bore/Stroke differences. If you look at the pressures and gases involved, and take into account pressure differential between the pre-cup and cylinder in relation to crank angle, even the small throat cup will work fine with injector tuning. I personally am going to put the bigger 7.3 throat cup in my 6.9 heads when I pull my engine back apart, just because Id rather have a shorter burn with all my fuel and a higher pop pressure, without having to jack the timing to hell with a lower pop and small cup throat, and really, until I get some real data from it, I don't know if it will make any difference anyway... All the precup hearsay floating around is just that, anybody actually tried it? I haven't seen anybody with back to back results, just a lot of talk... And most of it is Idiotic
In the end, trial and error is the only way to prove and disprove these theories. Prehaps tap the block for 1/2 studs and say good bye to HG problems.
The Ring-Lands are steel, and I highly doubt they would be effected at all even if you could shave them enough to get close. The thinnest part of the crown is a little more than 9/16 thick. Ive shaved as much as .080" off the pistons, and my own engine has .050" taken off. The weak spot on the piston is the edge next to the recardo "Chute", too much timing or EGT's and that will be the first part of the piston to go. I personally wont put an IDI that will see more load than stock together without ceramic coated tops, ive seen too many stock pistons melted there. Shaving the piston arguably helps to keep that edge from melting by taking the thin edge away.
And I don't really see how lower pop pressure makes a quieter running engine. I thought lower makes it louder because there is very little atomization with low pop pressures opposed to higher pop pressures. My 7.3 N/A IDI is louder than my bosses 1999 7.3 Powerstroke (When it used to run). Can you explain that? and yes it is timed correctly. Bone stock engine too.
The injector has very little to do with any atomization in an IDI, as soon as the fuel hits the precup/gp, its vaporized. As Mike said, a lower pop pressure makes for a longer injection duration by lowering total injection pressure. The longer injection duration means a more mellow, less violent burn... Less Noise, smoother running. Every stock IDI Ive ever heard is pretty quiet. As for comparison to the PSD, that's because it has split shot injectors, those PSD's were pretty quiet. Compare to a 94.5 PSD for noise, those are damn near as bad as a cummins.
And believe me, I've driven more Dodge 5.9s than you think. The noise in the cab gives me a headache after a while. The IDI is much smoother when cruising, but at idle, is worse than a PSD. At least mine is.
There are also rumors about larger precup throats making the engine run louder... That is simply not true at all. Precup throat size is for mpg OR Power, chose one. And the Hypermax about busting out freeze plugs is a lie. Trust me. Maybe we should meet up and build a 1200hp IDI and see if It's the truth or a blatant lie.
Id disagree about the pre-cups. I don't think they have much effect on anything aside from very small tuning in Bore/Stroke differences. If you look at the pressures and gases involved, and take into account pressure differential between the pre-cup and cylinder in relation to crank angle, even the small throat cup will work fine with injector tuning. I personally am going to put the bigger 7.3 throat cup in my 6.9 heads when I pull my engine back apart, just because Id rather have a shorter burn with all my fuel and a higher pop pressure, without having to jack the timing to hell with a lower pop and small cup throat, and really, until I get some real data from it, I don't know if it will make any difference anyway... All the precup hearsay floating around is just that, anybody actually tried it? I haven't seen anybody with back to back results, just a lot of talk... And most of it is Idiotic
In the end, trial and error is the only way to prove and disprove these theories. Prehaps tap the block for 1/2 studs and say good bye to HG problems.
#45
06-23-2014, 01:17 PM
I know the articles mike is talking about as well, and I just did a quick search but couldn't find anything right off the bat. But basically Mercedes was all about IDI until they realized they couldn't get rid of the parasitic loss from the heat entering the cooling system... That with DI-common rail being introduced, basically caused MB to switch to DI. The atomization of an IDI setup is way better than DI, and doesn't require the swirl like a DI engine does. Our heads flow better than any competitive DI engine out there because we don't have to swirl the air as it enters, so we get better VE. We use a little bit of the fuel energy to super atomize the fuel, but the benefit is a faster injection event, and that's why we can run less timing and more RPM. To summarize, IDI isn't an issue that limits our engines, its the other aspects like a crappy pump for performance, and small/qty head fasteners. The answer is in tuning and bigger/stronger head fasteners... Well know we are there when we start breaking bottom end parts...