Looking for missing power after 122HH upgrade...
07-18-2008, 01:14 PM
#51
I was not saying that its anyones job to provide the numbers at the seat, I was only asking to figure out more about the cam. More is learned from seat timing and this is who I build all my cams, not by the .050. I know comps lobes very well and use them alot, so I pretty much know your cam now.
Also, the other things most of you should get to understand is that Every cam has overlap. To say it has no overlap is wrong. When defining overlap, you should say this one cam has a lot less overlap than my last cam. It helps everyone else to understand more.
The reason why compression is a little more important in a blower like yours is due to the fact that the more air needed to fill a chamber, the hotter it gets. Same with going to a bigger camshaft. The blower will get hotter because you are asking it to feed more now.
This is also where the three rules apply to boost. Power is made by boost, timing then compression last. In that order do you build a platform. The reason this is important is because it comes down to how much boost are you running. Then what kind of timing do you want to run, and from there you can decide on how much compression you need. The reason the timing is important because you need to match timing to the cam profile. You can put X cam in there, and be so far off on timing because it pings that you are no longer "on" the camshaft for making power. So now everything is wrong. So instead of just throwing parts at it, try sitting down and figuring out everything I guess said here.
R
Also, the other things most of you should get to understand is that Every cam has overlap. To say it has no overlap is wrong. When defining overlap, you should say this one cam has a lot less overlap than my last cam. It helps everyone else to understand more.
The reason why compression is a little more important in a blower like yours is due to the fact that the more air needed to fill a chamber, the hotter it gets. Same with going to a bigger camshaft. The blower will get hotter because you are asking it to feed more now.
This is also where the three rules apply to boost. Power is made by boost, timing then compression last. In that order do you build a platform. The reason this is important is because it comes down to how much boost are you running. Then what kind of timing do you want to run, and from there you can decide on how much compression you need. The reason the timing is important because you need to match timing to the cam profile. You can put X cam in there, and be so far off on timing because it pings that you are no longer "on" the camshaft for making power. So now everything is wrong. So instead of just throwing parts at it, try sitting down and figuring out everything I guess said here.
R
07-18-2008, 02:12 PM
#52
Seems a bit like reverse engineering...not that it is a bad way to establish the end result. Deciding on a peak boost is a given, but why would you want to determine your compression and cam profile from a targeted timing rather than determining the most beneficial timing from the combined boost, compression and cam profiles?
Its not reverse. Its only reverse because you are only going in one direction now.
Plus, the answer is written in what I said.
R
07-18-2008, 05:06 PM
#53
Well Rick, your plan was somewhat followed...although I did mix the listed priority when determining compression and timing.
1. BOOST: The boost was predetermined at 10-11 lbs from a Magnuson 122HH--upgraded from the MP112 that you tuned on the 346. But even when spec'd (all engine info provided) to Magnuson, they were not able to deliver the correct pulley to provide the 10-11 lb target boost. They delivered it originally with a 3.0" pulley and we saw 6.5 lbs actual. We contacted them about this and they sent a 2.8 that gave 8 lbs actual. So, this leads me to believe that it isn't quite as easy as just plugging numbers into a calculator? That is why I am "throwing" an 8" crank pulley at it.
2-A. STATIC COMPRESSION: Certain components were a given in this build. Already having the AFR 225s that I bought from you for the 346, I knew that I would be working with those. The question was piston choice and I decided on a -7cc as it put to SCR at very close to 11-1, which I was advised as being a good target.
2-B. DYNAMIC COMPRESSION: To be honest, I knew (and know) very little about dynamic compression ratios, especially in stroker engines and when changing connecting rod length, cam profiles, etc. And the more I read the more confused I became in regard to my build. So, I started with what I had and tried to research/talk with people who had done similar projects. Unfortunately, there are many who have done twin-screw forced induction 370s (stock stroked 6.0L builds) but not so many 383s (stroked 5.7L builds)--so getting true comparisons are few.
I already had the GT2-3 in the 346, and consulted with LPE about its use in a FI 383--they have used it in that application and felt it would work well in mine. I felt that I had been given fairly experienced advice on using the GT2-3 in this build. Is it the right cam? I don't know but I will find out how it stands up to a cam spec'd by another reputable build of FI engines.
3. TIMING: Your advisory regarding selecting the desired timing ahead of compression is a new one on me...but as I have already admitted, I'm an apprentice trying to become a journeyman. Timing was never a question that was raised by anyone with whom I discussed my build with...including LPE or MTI. I have always thought of timing in a similar manner as fueling...you add or subtract to maximize the efficiency of the "air pump" that is being tuned. So, I'm a bit surprised that timing is one of the primary criteria to a build--or is this specific to properly designing a forced induction build?
Anyway, I am where I am and want to get to where I should be. So I will continue that quest with the two "next" steps...8" crank pulley and cam change. Should be interesting to see the results in any regard.
As always, I appreciate your input and will try to implement the principles you have outlined when inquiring as to which parts I should throw at my project next!
1. BOOST: The boost was predetermined at 10-11 lbs from a Magnuson 122HH--upgraded from the MP112 that you tuned on the 346. But even when spec'd (all engine info provided) to Magnuson, they were not able to deliver the correct pulley to provide the 10-11 lb target boost. They delivered it originally with a 3.0" pulley and we saw 6.5 lbs actual. We contacted them about this and they sent a 2.8 that gave 8 lbs actual. So, this leads me to believe that it isn't quite as easy as just plugging numbers into a calculator? That is why I am "throwing" an 8" crank pulley at it.
2-A. STATIC COMPRESSION: Certain components were a given in this build. Already having the AFR 225s that I bought from you for the 346, I knew that I would be working with those. The question was piston choice and I decided on a -7cc as it put to SCR at very close to 11-1, which I was advised as being a good target.
2-B. DYNAMIC COMPRESSION: To be honest, I knew (and know) very little about dynamic compression ratios, especially in stroker engines and when changing connecting rod length, cam profiles, etc. And the more I read the more confused I became in regard to my build. So, I started with what I had and tried to research/talk with people who had done similar projects. Unfortunately, there are many who have done twin-screw forced induction 370s (stock stroked 6.0L builds) but not so many 383s (stroked 5.7L builds)--so getting true comparisons are few.
I already had the GT2-3 in the 346, and consulted with LPE about its use in a FI 383--they have used it in that application and felt it would work well in mine. I felt that I had been given fairly experienced advice on using the GT2-3 in this build. Is it the right cam? I don't know but I will find out how it stands up to a cam spec'd by another reputable build of FI engines.
3. TIMING: Your advisory regarding selecting the desired timing ahead of compression is a new one on me...but as I have already admitted, I'm an apprentice trying to become a journeyman. Timing was never a question that was raised by anyone with whom I discussed my build with...including LPE or MTI. I have always thought of timing in a similar manner as fueling...you add or subtract to maximize the efficiency of the "air pump" that is being tuned. So, I'm a bit surprised that timing is one of the primary criteria to a build--or is this specific to properly designing a forced induction build?
Anyway, I am where I am and want to get to where I should be. So I will continue that quest with the two "next" steps...8" crank pulley and cam change. Should be interesting to see the results in any regard.
As always, I appreciate your input and will try to implement the principles you have outlined when inquiring as to which parts I should throw at my project next!
07-18-2008, 05:27 PM
#54
Well Rick, your plan was somewhat followed...although I did mix the listed priority when determining compression and timing.
1. BOOST: The boost was predetermined at 10-11 lbs from a Magnuson 122HH--upgraded from the MP112 that you tuned on the 346. But even when spec'd (all engine info provided) to Magnuson, they were not able to deliver the correct pulley to provide the 10-11 lb target boost. They delivered it originally with a 3.0" pulley and we saw 6.5 lbs actual. We contacted them about this and they sent a 2.8 that gave 8 lbs actual. So, this leads me to believe that it isn't quite as easy as just plugging numbers into a calculator? That is why I am "throwing" an 8" crank pulley at it.
2-A. STATIC COMPRESSION: Certain components were a given in this build. Already having the AFR 225s that I bought from you for the 346, I knew that I would be working with those. The question was piston choice and I decided on a -7cc as it put to SCR at very close to 11-1, which I was advised as being a good target.
2-B. DYNAMIC COMPRESSION: To be honest, I knew (and know) very little about dynamic compression ratios, especially in stroker engines and when changing connecting rod length, cam profiles, etc. And the more I read the more confused I became in regard to my build. So, I started with what I had and tried to research/talk with people who had done similar projects. Unfortunately, there are many who have done twin-screw forced induction 370s (stock stroked 6.0L builds) but not so many 383s (stroked 5.7L builds)--so getting true comparisons are few.
I already had the GT2-3 in the 346, and consulted with LPE about its use in a FI 383--they have used it in that application and felt it would work well in mine. I felt that I had been given fairly experienced advice on using the GT2-3 in this build. Is it the right cam? I don't know but I will find out how it stands up to a cam spec'd by another reputable build of FI engines.
3. TIMING: Your advisory regarding selecting the desired timing ahead of compression is a new one on me...but as I have already admitted, I'm an apprentice trying to become a journeyman. Timing was never a question that was raised by anyone with whom I discussed my build with...including LPE or MTI. I have always thought of timing in a similar manner as fueling...you add or subtract to maximize the efficiency of the "air pump" that is being tuned. So, I'm a bit surprised that timing is one of the primary criteria to a build--or is this specific to properly designing a forced induction build?
Anyway, I am where I am and want to get to where I should be. So I will continue that quest with the two "next" steps...8" crank pulley and cam change. Should be interesting to see the results in any regard.
As always, I appreciate your input and will try to implement the principles you have outlined when inquiring as to which parts I should throw at my project next!
1. BOOST: The boost was predetermined at 10-11 lbs from a Magnuson 122HH--upgraded from the MP112 that you tuned on the 346. But even when spec'd (all engine info provided) to Magnuson, they were not able to deliver the correct pulley to provide the 10-11 lb target boost. They delivered it originally with a 3.0" pulley and we saw 6.5 lbs actual. We contacted them about this and they sent a 2.8 that gave 8 lbs actual. So, this leads me to believe that it isn't quite as easy as just plugging numbers into a calculator? That is why I am "throwing" an 8" crank pulley at it.
2-A. STATIC COMPRESSION: Certain components were a given in this build. Already having the AFR 225s that I bought from you for the 346, I knew that I would be working with those. The question was piston choice and I decided on a -7cc as it put to SCR at very close to 11-1, which I was advised as being a good target.
2-B. DYNAMIC COMPRESSION: To be honest, I knew (and know) very little about dynamic compression ratios, especially in stroker engines and when changing connecting rod length, cam profiles, etc. And the more I read the more confused I became in regard to my build. So, I started with what I had and tried to research/talk with people who had done similar projects. Unfortunately, there are many who have done twin-screw forced induction 370s (stock stroked 6.0L builds) but not so many 383s (stroked 5.7L builds)--so getting true comparisons are few.
I already had the GT2-3 in the 346, and consulted with LPE about its use in a FI 383--they have used it in that application and felt it would work well in mine. I felt that I had been given fairly experienced advice on using the GT2-3 in this build. Is it the right cam? I don't know but I will find out how it stands up to a cam spec'd by another reputable build of FI engines.
3. TIMING: Your advisory regarding selecting the desired timing ahead of compression is a new one on me...but as I have already admitted, I'm an apprentice trying to become a journeyman. Timing was never a question that was raised by anyone with whom I discussed my build with...including LPE or MTI. I have always thought of timing in a similar manner as fueling...you add or subtract to maximize the efficiency of the "air pump" that is being tuned. So, I'm a bit surprised that timing is one of the primary criteria to a build--or is this specific to properly designing a forced induction build?
Anyway, I am where I am and want to get to where I should be. So I will continue that quest with the two "next" steps...8" crank pulley and cam change. Should be interesting to see the results in any regard.
As always, I appreciate your input and will try to implement the principles you have outlined when inquiring as to which parts I should throw at my project next!
So look at it this way. I want 10psi.....So I figure I want that with what ever cubes I want. Ok....
With knowing the cubes, I can look at my goals in power and operating range. I want a 2-6K operating range for my motor. Ok, I dont need anymore than X amount of duration on the exhaust or intake to do that. Fine...
Now with that being said, cam is about X big, cubes x big, and desired boost about 10psi to hopefully get me to my goal, the camshaft should now take about X amount of timing to be optimal. Second factor.
So when I say coming " on " or " off " a camshaft with timing, I am talking about the point where you dont have enough or you have too much. There are times where you make bad HP per psi, and times where you make good. Its because the timing is in the sweet spot for that camshaft.
Third item, to do all this with X octane, I need X compression. Starting to see where I am going with this now? It sounds backwards, when really if you do it a lot it becomes second nature and you can figure out cams for FI real fast in what will get you great power and work good all the time.
So the issue you will have colby is that in order for you to make power upstairs, you will need to keep going up on timing with the cam you are going to use. And with this, your octane rating and your compression on the motor will be the only factors holding you back on whether or not you can use the amount of timing required to do it.
The other scary part about you trying to grab a number now, and trying to have such high compression to do it is your chance for blowing the motor on a nice cool night. It will happen. You will heat soak on the dyno, add the timing needed for the blower to make power, and you will start it up one day, go hammer on it and find that it needed about 4 degrees less or so because the air just became real dense.
R
07-19-2008, 11:36 AM
#55
Ahhh Sooo...
So the issue you will have colby is that in order for you to make power upstairs, you will need to keep going up on timing with the cam you are going to use. And with this, your octane rating and your compression on the motor will be the only factors holding you back on whether or not you can use the amount of timing required to do it.
R
R
With too low of compression the timing will have to be too high to reach the target numbers without the use of racing gas, and with too high of compression timing will have to be set too low (even with racing gas) to reach the target numbers?
So what is the ideal timing with our sometimes questionable 91 octane pump fuel?
And at what point do we safely mask our comparatively low octane with methanol...an additional 3*, 5*, 8*?
07-19-2008, 11:51 AM
#56
If there is anything false to be known about meth is that we all think meth allows us to run more timing. Wrong....Meth allows us all to run our boost and timing levels safley. Just like race gas.
You are correct in some ways. If your compression is too high, your chamber will be on the edge of unstable without the use of higher octane all the time. This is not just WOT, but part throttle as well. And if you have too low like you said, you can crank timing in all day, but may never reach your goal because you are trying to fill a cylinder that cant be filled.
Now low compression is great and ideal, but only on FI that has a dense charge like a centri blower or a turbo. In that case its an easy one to pick timing. The posi blower is a little tougher. It needs that compression to back it so you dont demand the blower so much to fill what it cant fill. Sure you can add cylinder pressure by cranking timing in, but again, now it becomes unstable all the time.
R
You are correct in some ways. If your compression is too high, your chamber will be on the edge of unstable without the use of higher octane all the time. This is not just WOT, but part throttle as well. And if you have too low like you said, you can crank timing in all day, but may never reach your goal because you are trying to fill a cylinder that cant be filled.
Now low compression is great and ideal, but only on FI that has a dense charge like a centri blower or a turbo. In that case its an easy one to pick timing. The posi blower is a little tougher. It needs that compression to back it so you dont demand the blower so much to fill what it cant fill. Sure you can add cylinder pressure by cranking timing in, but again, now it becomes unstable all the time.
R
07-19-2008, 03:02 PM
#59