Discussion about turbo cams, overlap, boost and reversion
06-15-2009, 01:23 PM
#62
surprised no one has mentioned anything of Speed Inc's turbo cams...
233/233 .595/.598 112 lsa
TU0 216 216 .561 .561 114
TU1 225 225 .581 .581 113
TU2 236 236 .587 .587 112.5
TU3 240 240 .588 .588 112
if you guys search here you can see as when they lowered the LSA the car picked up power everywhere, each time.
and if people can't understand why Shawn, Kurt, etc. don't want to share their cam specs...
Chad
233/233 .595/.598 112 lsa
TU0 216 216 .561 .561 114
TU1 225 225 .581 .581 113
TU2 236 236 .587 .587 112.5
TU3 240 240 .588 .588 112
if you guys search here you can see as when they lowered the LSA the car picked up power everywhere, each time.
and if people can't understand why Shawn, Kurt, etc. don't want to share their cam specs...
Chad
06-15-2009, 01:49 PM
#63
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surprised no one has mentioned anything of Speed Inc's turbo cams...
233/233 .595/.598 112 lsa
TU0 216 216 .561 .561 114
TU1 225 225 .581 .581 113
TU2 236 236 .587 .587 112.5
TU3 240 240 .588 .588 112
if you guys search here you can see as when they lowered the LSA the car picked up power everywhere, each time.
and if people can't understand why Shawn, Kurt, etc. don't want to share their cam specs...
Chad
233/233 .595/.598 112 lsa
TU0 216 216 .561 .561 114
TU1 225 225 .581 .581 113
TU2 236 236 .587 .587 112.5
TU3 240 240 .588 .588 112
if you guys search here you can see as when they lowered the LSA the car picked up power everywhere, each time.
and if people can't understand why Shawn, Kurt, etc. don't want to share their cam specs...
Chad
Picked up power,hp or tq?What do those numbers equate to?How does that power work in a specfic combo?Can you spool the turbos where you want to?is it responsive or have a huge lag?These are all questions that should be asked.Like i said before any cam will make hp in a turbo motor-the right one will make the power you need where you need it without sacrificing much if any top end hp.We have found at the dragstrip the cam that makes the most horsepower doesnt mean it will make the lowest et.Cams with lower overlaps will make more low end tq which make for more boost at lower rpms and faster ets,cam timing also is very valuable,just cause you have the correct cam doesnt mean it will work great out of the box.We have advanced cams as much as 12 deg to make them work properly.
Sorry for not giving the exact info everybody wants,but i do believe i gave some good info.Now you do what you want with it.
06-15-2009, 04:20 PM
#64
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Picked up power,hp or tq?What do those numbers equate to?How does that power work in a specfic combo?Can you spool the turbos where you want to?is it responsive or have a huge lag?These are all questions that should be asked.Like i said before any cam will make hp in a turbo motor-the right one will make the power you need where you need it without sacrificing much if any top end hp.We have found at the dragstrip the cam that makes the most horsepower doesnt mean it will make the lowest et.Cams with lower overlaps will make more low end tq which make for more boost at lower rpms and faster ets,cam timing also is very valuable,just cause you have the correct cam doesnt mean it will work great out of the box.We have advanced cams as much as 12 deg to make them work properly.
Sorry for not giving the exact info everybody wants,but i do believe i gave some good info.Now you do what you want with it.
Sorry for not giving the exact info everybody wants,but i do believe i gave some good info.Now you do what you want with it.
Mark
06-15-2009, 05:21 PM
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Picked up power,hp or tq?What do those numbers equate to?How does that power work in a specfic combo?Can you spool the turbos where you want to?is it responsive or have a huge lag?These are all questions that should be asked.Like i said before any cam will make hp in a turbo motor-the right one will make the power you need where you need it without sacrificing much if any top end hp.We have found at the dragstrip the cam that makes the most horsepower doesnt mean it will make the lowest et.Cams with lower overlaps will make more low end tq which make for more boost at lower rpms and faster ets,cam timing also is very valuable,just cause you have the correct cam doesnt mean it will work great out of the box.We have advanced cams as much as 12 deg to make them work properly.
Sorry for not giving the exact info everybody wants,but i do believe i gave some good info.Now you do what you want with it.
Sorry for not giving the exact info everybody wants,but i do believe i gave some good info.Now you do what you want with it.
06-15-2009, 07:56 PM
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Picked up power,hp or tq?What do those numbers equate to?How does that power work in a specfic combo?Can you spool the turbos where you want to?is it responsive or have a huge lag?These are all questions that should be asked.Like i said before any cam will make hp in a turbo motor-the right one will make the power you need where you need it without sacrificing much if any top end hp.We have found at the dragstrip the cam that makes the most horsepower doesnt mean it will make the lowest et.Cams with lower overlaps will make more low end tq which make for more boost at lower rpms and faster ets,cam timing also is very valuable,just cause you have the correct cam doesnt mean it will work great out of the box.We have advanced cams as much as 12 deg to make them work properly.
Sorry for not giving the exact info everybody wants,but i do believe i gave some good info.Now you do what you want with it.
Sorry for not giving the exact info everybody wants,but i do believe i gave some good info.Now you do what you want with it.
Example (NOT FACT)
LSA effects top end HP...
Duration can effect...
Reverse split prevents reversion which builds TQ low..
I am a noob to this and Jermey (Zombie) has shed more light on Cam facts then I ever professed to know. There are those of you who fully understand these effects and I understand and appreciate that you are making a living on this business. So dont tell us your secrets (I fully understand)... but instead educate us some if you will!
06-15-2009, 11:32 PM
#69
Not to be the devils advocate here....but throwing a cam on the 'ole CAM DOCTOR machine tells all...
BUT......i can appreciate the work and $$$ it takes somebody to acheive results, and if he wants to keep those private, it's his right.
BUT......i can appreciate the work and $$$ it takes somebody to acheive results, and if he wants to keep those private, it's his right.
06-16-2009, 11:12 AM
#72
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You can't generalize, and come up with one turbo cam that works for all.
I gave my example of running the 236/236 Speed Inc. grind. I know three other folks running it. They run 370 cid up to 408 cid engines. Two of the other cars are twins, and one is a big single. Of the four combos, mine was significantly more laggy due (a) running the least amount of cubes, (b) least amount of compression, and (c) a big turbo.
I could ask my friend who also had a butt turbo, who ran faster than you, what cam he had in his car when he was running that setup. Let me know if you'd like me to call him and ask.
But engine size/ compression, turbo(s) size, max rpms, and a lot of other things are going to influence cam selections.
I do recall that Mark K. (blwnta) was at one time running an old Mike Brown OH Boys cam grind last year or the year before. I'm guessing it was a reverse split, with less exhaust duration, and I'm guessing that Kurt Urban or W2W may have had some input into some of those cam designs. I would not be surprised if the intake duration was over 240, maybe even 244 or even 250. But they run big singles and have been running in the 7's for many years. I'm not sure how that info (if I am somewhat accurate) would help you with your rear-mounted pump gas setup.
Jim M. (Intmd8) has dynoed and messed with a lot of different cam grinds and his experience would be very relevant for you, as he's built and dynoed a lot of turbo setups that street driven. He suggested I run more compression, and he was totally right.
I gave my example of running the 236/236 Speed Inc. grind. I know three other folks running it. They run 370 cid up to 408 cid engines. Two of the other cars are twins, and one is a big single. Of the four combos, mine was significantly more laggy due (a) running the least amount of cubes, (b) least amount of compression, and (c) a big turbo.
I could ask my friend who also had a butt turbo, who ran faster than you, what cam he had in his car when he was running that setup. Let me know if you'd like me to call him and ask.
But engine size/ compression, turbo(s) size, max rpms, and a lot of other things are going to influence cam selections.
I do recall that Mark K. (blwnta) was at one time running an old Mike Brown OH Boys cam grind last year or the year before. I'm guessing it was a reverse split, with less exhaust duration, and I'm guessing that Kurt Urban or W2W may have had some input into some of those cam designs. I would not be surprised if the intake duration was over 240, maybe even 244 or even 250. But they run big singles and have been running in the 7's for many years. I'm not sure how that info (if I am somewhat accurate) would help you with your rear-mounted pump gas setup.
Jim M. (Intmd8) has dynoed and messed with a lot of different cam grinds and his experience would be very relevant for you, as he's built and dynoed a lot of turbo setups that street driven. He suggested I run more compression, and he was totally right.
06-16-2009, 11:18 AM
#73
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You can't generalize, and come up with one turbo cam that works for all.
I gave my example of running the 236/236 Speed Inc. grind. I know three other folks running it. They run 370 cid up to 408 cid engines. Two of the other cars are twins, and one is a big single. Of the four combos, mine was significantly more laggy due (a) running the least amount of cubes, (b) least amount of compression, and (c) a big turbo.
I could ask my friend who also had a butt turbo, who ran faster than you, what cam he had in his car when he was running that setup. Let me know if you'd like me to call him and ask.
But engine size/ compression, turbo(s) size, max rpms, and a lot of other things are going to influence cam selections.
I do recall that Mark K. (blwnta) was at one time running an old Mike Brown OH Boys cam grind last year or the year before. I'm guessing it was a reverse split, with less exhaust duration, and I'm guessing that Kurt Urban or W2W may have had some input into some of those cam designs. I would not be surprised if the intake duration was over 240, maybe even 244 or even 250. But they run big singles and have been running in the 7's for many years. I'm not sure how that info (if I am somewhat accurate) would help you with your rear-mounted pump gas setup.
Jim M. (Intmd8) has dynoed and messed with a lot of different cam grinds and his experience would be very relevant for you, as he's built and dynoed a lot of turbo setups that street driven. He suggested I run more compression, and he was totally right.
I gave my example of running the 236/236 Speed Inc. grind. I know three other folks running it. They run 370 cid up to 408 cid engines. Two of the other cars are twins, and one is a big single. Of the four combos, mine was significantly more laggy due (a) running the least amount of cubes, (b) least amount of compression, and (c) a big turbo.
I could ask my friend who also had a butt turbo, who ran faster than you, what cam he had in his car when he was running that setup. Let me know if you'd like me to call him and ask.
But engine size/ compression, turbo(s) size, max rpms, and a lot of other things are going to influence cam selections.
I do recall that Mark K. (blwnta) was at one time running an old Mike Brown OH Boys cam grind last year or the year before. I'm guessing it was a reverse split, with less exhaust duration, and I'm guessing that Kurt Urban or W2W may have had some input into some of those cam designs. I would not be surprised if the intake duration was over 240, maybe even 244 or even 250. But they run big singles and have been running in the 7's for many years. I'm not sure how that info (if I am somewhat accurate) would help you with your rear-mounted pump gas setup.
Jim M. (Intmd8) has dynoed and messed with a lot of different cam grinds and his experience would be very relevant for you, as he's built and dynoed a lot of turbo setups that street driven. He suggested I run more compression, and he was totally right.
06-16-2009, 11:23 AM
#74
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There are so many theories out there....hell, half of the going-ons in a turbo motor is still sketchy. I've seen a certain type of cam work. It doesn't mean its the cam for everyone though. Why did it work in one guys car...I have no idea, but it ran REALLY well for its time. I tried it in my car and it didn't work worth a ****. I think I know why, but it could be other reasons too. I'd like to try some revisions of those cams that didn't work later on. For the moment, I'm using a cookie-cutter grind.
06-16-2009, 11:34 AM
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One problem is the dynamics inside of a turbo motor are very very complex
N/A cam theory is pretty well understood...much of which doesn't apply to a turbo car since its running into a substantial head pressure. As boost(power) goes up there's more available pressure residual in the cylinder which is fighting increasing exhaust backpressure. All this air also has mass so you have to consider inertia (air has to accelerate and will resist turning directions, etc)
I believe that the intake closing point dictates the off-boost/low boost characterisitics since this directly controls the dynamic compression ratio...probably why almost every turbo cam out there is advanced to some degree or run a "traditional" split like 112ish
Beyond that, I believe alot of cam profiles are out there as a result of trial-and-error
N/A cam theory is pretty well understood...much of which doesn't apply to a turbo car since its running into a substantial head pressure. As boost(power) goes up there's more available pressure residual in the cylinder which is fighting increasing exhaust backpressure. All this air also has mass so you have to consider inertia (air has to accelerate and will resist turning directions, etc)
I believe that the intake closing point dictates the off-boost/low boost characterisitics since this directly controls the dynamic compression ratio...probably why almost every turbo cam out there is advanced to some degree or run a "traditional" split like 112ish
Beyond that, I believe alot of cam profiles are out there as a result of trial-and-error
06-16-2009, 11:37 AM
#76
One problem is the dynamics inside of a turbo motor are very very complex
N/A cam theory is pretty well understood...much of which doesn't apply to a turbo car since its running into a substantial head pressure. As boost(power) goes up there's more available pressure residual in the cylinder which is fighting increasing exhaust backpressure. All this air also has mass so you have to consider inertia (air has to accelerate and will resist turning directions, etc)
I believe that the intake closing point dictates the off-boost/low boost characterisitics since this directly controls the dynamic compression ratio...probably why almost every turbo cam out there is advanced to some degree or run a "traditional" split like 112ish
N/A cam theory is pretty well understood...much of which doesn't apply to a turbo car since its running into a substantial head pressure. As boost(power) goes up there's more available pressure residual in the cylinder which is fighting increasing exhaust backpressure. All this air also has mass so you have to consider inertia (air has to accelerate and will resist turning directions, etc)
I believe that the intake closing point dictates the off-boost/low boost characterisitics since this directly controls the dynamic compression ratio...probably why almost every turbo cam out there is advanced to some degree or run a "traditional" split like 112ish
06-16-2009, 11:59 AM
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06-16-2009, 12:40 PM
#80
I don't think Zombie is as interested in what cams work well as he is why a cam is designed a certain way.
For instance, it's easy to say, "Joe Bob has a cam that's 240/230-114, +4 and his car runs 8's." Despite the fact that this is basically worthless information since there is no frame of reference, it also isn't helpful because there is no discussion about why particular specs work or don't work.
For instance, take one aspect of cam design, say EVO. An average high performance NA engine with a reasonable E/I head flow balance will work well with an EVO around 60 deg BBDC. Now, add 30-50 psi of exhaust pressure, a compression ratio of 8.5/1, and 2x the mass in the cylinder, and which way should the EVO move, how much, and why? Just an example...
For instance, it's easy to say, "Joe Bob has a cam that's 240/230-114, +4 and his car runs 8's." Despite the fact that this is basically worthless information since there is no frame of reference, it also isn't helpful because there is no discussion about why particular specs work or don't work.
For instance, take one aspect of cam design, say EVO. An average high performance NA engine with a reasonable E/I head flow balance will work well with an EVO around 60 deg BBDC. Now, add 30-50 psi of exhaust pressure, a compression ratio of 8.5/1, and 2x the mass in the cylinder, and which way should the EVO move, how much, and why? Just an example...