Getting reversion and need some advise
#22
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Anyone ever wonder why some guys get away with running unheard of amounts initial compression with pump gas and get away with it? This is one of the contributing factors...
#23
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I've had the blower off a few times to deal with the coupler issue, and I haven not seen any noticeable carbon staining of the intake ports, but it's something I'll look at next season.
I do have to ask... the rule of thumb is that it's hard to have too much cylinder head in a blown application... with what has been said on this thread, does this mean that most of this rule is out the window? I've read a lot about this subject (including here on OSO), and talked to very knowledgeable people on this... it seems that most follow this rule. I am not at all doubting that intake reversion is a possibility with a NA engine, but everything I've studied says the opposite when using a positive displacement blower. The rotors are spinning and still moving air at idle.... more than what would be put through with vacuum alone. I've also got good idle vacuum per my gauge so it's not like the intake ports are dead at idle.
I understand that the chosen head is huge compared to the displacement, but changing them out is not an option at this time.
I do have to ask... the rule of thumb is that it's hard to have too much cylinder head in a blown application... with what has been said on this thread, does this mean that most of this rule is out the window? I've read a lot about this subject (including here on OSO), and talked to very knowledgeable people on this... it seems that most follow this rule. I am not at all doubting that intake reversion is a possibility with a NA engine, but everything I've studied says the opposite when using a positive displacement blower. The rotors are spinning and still moving air at idle.... more than what would be put through with vacuum alone. I've also got good idle vacuum per my gauge so it's not like the intake ports are dead at idle.
I understand that the chosen head is huge compared to the displacement, but changing them out is not an option at this time.
#24
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I've had the blower off a few times to deal with the coupler issue, and I haven not seen any noticeable carbon staining of the intake ports, but it's something I'll look at next season.
I do have to ask... the rule of thumb is that it's hard to have too much cylinder head in a blown application... with what has been said on this thread, does this mean that most of this rule is out the window? I've read a lot about this subject (including here on OSO), and talked to very knowledgeable people on this... it seems that most follow this rule. I am not at all doubting that intake reversion is a possibility with a NA engine, but everything I've studied says the opposite when using a positive displacement blower. The rotors are spinning and still moving air at idle.... more than what would be put through with vacuum alone. I've also got good idle vacuum per my gauge so it's not like the intake ports are dead at idle.
I understand that the chosen head is huge compared to the displacement, but changing them out is not an option at this time.
I do have to ask... the rule of thumb is that it's hard to have too much cylinder head in a blown application... with what has been said on this thread, does this mean that most of this rule is out the window? I've read a lot about this subject (including here on OSO), and talked to very knowledgeable people on this... it seems that most follow this rule. I am not at all doubting that intake reversion is a possibility with a NA engine, but everything I've studied says the opposite when using a positive displacement blower. The rotors are spinning and still moving air at idle.... more than what would be put through with vacuum alone. I've also got good idle vacuum per my gauge so it's not like the intake ports are dead at idle.
I understand that the chosen head is huge compared to the displacement, but changing them out is not an option at this time.
#25
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iTrader: (3)
I've had the blower off a few times to deal with the coupler issue, and I haven not seen any noticeable carbon staining of the intake ports, but it's something I'll look at next season.
I do have to ask... the rule of thumb is that it's hard to have too much cylinder head in a blown application... with what has been said on this thread, does this mean that most of this rule is out the window? I've read a lot about this subject (including here on OSO), and talked to very knowledgeable people on this... it seems that most follow this rule. I am not at all doubting that intake reversion is a possibility with a NA engine, but everything I've studied says the opposite when using a positive displacement blower. The rotors are spinning and still moving air at idle.... more than what would be put through with vacuum alone. I've also got good idle vacuum per my gauge so it's not like the intake ports are dead at idle.
I understand that the chosen head is huge compared to the displacement, but changing them out is not an option at this time.
I do have to ask... the rule of thumb is that it's hard to have too much cylinder head in a blown application... with what has been said on this thread, does this mean that most of this rule is out the window? I've read a lot about this subject (including here on OSO), and talked to very knowledgeable people on this... it seems that most follow this rule. I am not at all doubting that intake reversion is a possibility with a NA engine, but everything I've studied says the opposite when using a positive displacement blower. The rotors are spinning and still moving air at idle.... more than what would be put through with vacuum alone. I've also got good idle vacuum per my gauge so it's not like the intake ports are dead at idle.
I understand that the chosen head is huge compared to the displacement, but changing them out is not an option at this time.
#26
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Here is a post on another forum from Darin Morgan. One of the best cylinder head guys in the country.
The chamber design and camshaft exhaust duration are two huge factors for both supercharged and Nitrous engines. They are basically the exact opposite of what you would do for an NA engine. In an NA engine the quench/squish area is overwhelmingly important. In a supercharged or nitrous engine its important to get rid of all the squish quench area. The pressure rise and flame travel is so fast they a high squish chamber will end gas detonate even though the squish quench is trying to cool the mixture.
If you design a port for an NA engine that's what works best in both Nitrous and supercharged engines. Some people mistakenly try and make them bigger and the engine never responds properly when you do this. I have done some pretty extensive R&D with supercharged stuff in the last 8 years and have tried many different port designs. I of course tried to get fancy and calculate how much bigger the port "should" be and every single time I enlarged it, the engine lost power. Now, your going to ask me why this happens. On this one, I will have to say that I (as well as everyone else I have asked) dont know. I am sure it has to do with the density and heat of the charge relative to NA but I cant quite put my finger on it. I have asked every single engineer and supercharged engine builder I can because its very perplexing to me but no one knows.
Darin Morgan
The chamber design and camshaft exhaust duration are two huge factors for both supercharged and Nitrous engines. They are basically the exact opposite of what you would do for an NA engine. In an NA engine the quench/squish area is overwhelmingly important. In a supercharged or nitrous engine its important to get rid of all the squish quench area. The pressure rise and flame travel is so fast they a high squish chamber will end gas detonate even though the squish quench is trying to cool the mixture.
If you design a port for an NA engine that's what works best in both Nitrous and supercharged engines. Some people mistakenly try and make them bigger and the engine never responds properly when you do this. I have done some pretty extensive R&D with supercharged stuff in the last 8 years and have tried many different port designs. I of course tried to get fancy and calculate how much bigger the port "should" be and every single time I enlarged it, the engine lost power. Now, your going to ask me why this happens. On this one, I will have to say that I (as well as everyone else I have asked) dont know. I am sure it has to do with the density and heat of the charge relative to NA but I cant quite put my finger on it. I have asked every single engineer and supercharged engine builder I can because its very perplexing to me but no one knows.
Darin Morgan
#27
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Couple things I can do...
1. Play with the timing a little. It's locked at 32, and to get it to idle right I'll probably need a get a custom stop for my distributor. Worth a try though.
2. I have some room to extend the inner pipe on my tips. I can get some 3" pipe with an expanded end to try slipping over the internal pipe end. From there I can play with the length to see what happens.
3. Definitely changing the manifold gaskets.
If I was going to covert to dry tails, can I do it with my existing risers? What about keeping the rubber good? Can I introduce "some" water?
Thanks for all the help everyone.
1. Play with the timing a little. It's locked at 32, and to get it to idle right I'll probably need a get a custom stop for my distributor. Worth a try though.
2. I have some room to extend the inner pipe on my tips. I can get some 3" pipe with an expanded end to try slipping over the internal pipe end. From there I can play with the length to see what happens.
3. Definitely changing the manifold gaskets.
If I was going to covert to dry tails, can I do it with my existing risers? What about keeping the rubber good? Can I introduce "some" water?
Thanks for all the help everyone.
#28
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More hp in a given engine size creates heat , and heated lake water outflow and volume. Fairly easy to run what you need through the exhaust to keep the rubber alive and the sound down , and send the rest out a starboard side hull fitting. May pick up a few ponies too, if your moving lots of water.
#29
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couple of things, anytime you have blower surge can revert bad during that time, during that cycle becomes a vacuum, I see your water dumps at front of tail pipes, can you move to the rear ? may be enough to stop it..of course dry is best
#30
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I was thinking about welding up the holes on the riser (there are 8... maybe leave the two on top open), add bungs to the outer jacket of the riser, and dump the excess water overboard. Good plan?