Turbo cams: VA Speed vs Speed Inc vs Brute Speed vs LS9?
09-16-2010, 05:14 PM
#41
Well aside from all the gun slinging. I had that same turbo, bigger cubes tho on a rearmount car and i used the brute speed cam. The highest power that I made was 813 hp and 713 tq on 18 psi. I like the brute speed cam because of the nasty mid rang and wicked top end.It also sounded wicked.
I ran a reverse spit cam befor on my 346 and it did good 7-9 psi stock heads tho. I dont have a comparsion tho becuase the builds are way differant. But my vote is the brute speed cam. I also like the speed inc grind cam also, I race a guy with one and won but it was really one sided due to the fact he had a stock block. But at the time he was really bashing my ****.......
I ran a reverse spit cam befor on my 346 and it did good 7-9 psi stock heads tho. I dont have a comparsion tho becuase the builds are way differant. But my vote is the brute speed cam. I also like the speed inc grind cam also, I race a guy with one and won but it was really one sided due to the fact he had a stock block. But at the time he was really bashing my ****.......
09-16-2010, 05:28 PM
#42
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Hi Jim!
Those numbers are why generalization can get confusing!
I have found the turbo engines will take more duration and make more power, no suprise really. The problem with the larger ex stuff that I have seen is they start wanting more timing for the same power and don't re accelerate as well on a gear change. I suspect that the backpressure is starting to cause the next cycle to be contaminated making the egr type timing numbers happen. Some free flowing engines with tight gearing I have out running are using splits that look like motor cams! Mike Brown has 6 more degrees on the ex, but I did not do that for ultimate power, I changed that to help him race the car more consistant.
So if a 224-224 lobe in a traditional limited turbo engine makes it drive nice and perform well, then putting 6-8 more degrees of intake duration in it should pack the cylinder with more air and not create more reversion since the ex cycle did not change, just a minor overlap change. This should produce more power without hurting it's ability to pull the bottom of the gear. In my testing that made the car faster (my truck actually), but it was a heavy vehicle with a limited turbo. The engine dyno only showed minor tq losses early with the bigger camshaft. On the engine dyno the factory LS6 cam made nice peak power!
I usually pick cams for engines based on my time spent braking stuff mixed in with what I percieve is the driving ability of the guy behind the wheel.
In the end the debate may never end........
Kurt
Those numbers are why generalization can get confusing!
I have found the turbo engines will take more duration and make more power, no suprise really. The problem with the larger ex stuff that I have seen is they start wanting more timing for the same power and don't re accelerate as well on a gear change. I suspect that the backpressure is starting to cause the next cycle to be contaminated making the egr type timing numbers happen. Some free flowing engines with tight gearing I have out running are using splits that look like motor cams! Mike Brown has 6 more degrees on the ex, but I did not do that for ultimate power, I changed that to help him race the car more consistant.
So if a 224-224 lobe in a traditional limited turbo engine makes it drive nice and perform well, then putting 6-8 more degrees of intake duration in it should pack the cylinder with more air and not create more reversion since the ex cycle did not change, just a minor overlap change. This should produce more power without hurting it's ability to pull the bottom of the gear. In my testing that made the car faster (my truck actually), but it was a heavy vehicle with a limited turbo. The engine dyno only showed minor tq losses early with the bigger camshaft. On the engine dyno the factory LS6 cam made nice peak power!
I usually pick cams for engines based on my time spent braking stuff mixed in with what I percieve is the driving ability of the guy behind the wheel.
In the end the debate may never end........
Kurt
Hi Kurt 
What is it you like about a reverse split cam on a turbo application? What are you trying to achieve with the valve events that the cam ends up being that way?
Another thing is, I wish we were talking more actual numbers.
I mean, if my cam is 225/225 @.050 and someone goes with a 225/223 @.050 because it's a reverse split I find that amusing as the valve events would be very similar.
What is it you like about a reverse split cam on a turbo application? What are you trying to achieve with the valve events that the cam ends up being that way?
Another thing is, I wish we were talking more actual numbers.
I mean, if my cam is 225/225 @.050 and someone goes with a 225/223 @.050 because it's a reverse split I find that amusing as the valve events would be very similar.
09-16-2010, 05:43 PM
#43
Custom cams aren't much more if any more over an off the shelf grind. VA Speed sold me a 236/236 .617 on a 114 for my 408 with an 88 mm turbo. I would either get a single pattern or reverse split on a front mounted turbo. Supercharged or rear mounted a conventional split because I think in both applications you need more exhaust flow. Too many FAST cars are running single pattern or reverse split with a front mount and hauling ***
09-16-2010, 06:29 PM
#44
I also have a 4276, although i have a 1.12 ar, with a built 370. With so many possible variations in what you want to do, and how the car is setup i think you should always go with a custom cam. As the guy above me said what is it 20 bucks more? maybe not more at all, just deal with one of the big shops, and while there guess for you may not be the absolute best, it will probably be better then an off the shelf cam.
Chris
Chris
09-16-2010, 08:05 PM
#45
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i believe that your comment was that sbc's don't work well with reverse splits-this is a sbc with a reverse split.It may be extreme-but you over generalized your statement and i was providing proof that said it does work.
09-17-2010, 08:59 AM
#46
Hey, do you happen to have all the cam specs that were tried in your buddies 105 mm combo, any other coincident changes made, corresponding quarter mile times (with mph), and ambient conditions?
To this day, with all the people in the world claiming reverse-splits are better, I have NEVER seen actual consistent data proving this. I have seen data proving the opposite.
09-17-2010, 09:06 AM
#47
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Forgive me for assuming we were all talking about 800 - 1100 hp engines here.
Hey, do you happen to have all the cam specs that were tried in your buddies 105 mm combo, any other coincident changes made, corresponding quarter mile times (with mph), and ambient conditions?
To this day, with all the people in the world claiming reverse-splits are better, I have NEVER seen actual consistent data proving this. I have seen data proving the opposite.
Hey, do you happen to have all the cam specs that were tried in your buddies 105 mm combo, any other coincident changes made, corresponding quarter mile times (with mph), and ambient conditions?
To this day, with all the people in the world claiming reverse-splits are better, I have NEVER seen actual consistent data proving this. I have seen data proving the opposite.
just looking at power is the wrong approach on a turbo car...spooling is a big issue too...I know we were able to use a converter that was tough for a BBC car to spool on my little 366/98mm combo...it was all in the cam selection
09-17-2010, 09:32 AM
#48
Forgive me for assuming we were all talking about 800 - 1100 hp engines here.
Hey, do you happen to have all the cam specs that were tried in your buddies 105 mm combo, any other coincident changes made, corresponding quarter mile times (with mph), and ambient conditions?
To this day, with all the people in the world claiming reverse-splits are better, I have NEVER seen actual consistent data proving this. I have seen data proving the opposite.
Hey, do you happen to have all the cam specs that were tried in your buddies 105 mm combo, any other coincident changes made, corresponding quarter mile times (with mph), and ambient conditions?
To this day, with all the people in the world claiming reverse-splits are better, I have NEVER seen actual consistent data proving this. I have seen data proving the opposite.
09-17-2010, 10:15 AM
#49
If you were paying attention, you would know that I was one of only 2 people in this thread that actually tried more than one cam in a turbo motor, without making other changes at the same time, and have documented gains (er, losses) in 800-1000 hp combo's. I lost power and my car slowed when I went from a conventional split pattern to a single pattern of similar specs. I can find no reason to believe that going further in that direction would yield a different result. I made my recommendation several pages ago based on my experience.
09-17-2010, 10:28 AM
#50
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If you were paying attention, you would know that I was one of only 2 people in this thread that actually tried more than one cam in a turbo motor, without making other changes at the same time, and have documented gains (er, losses) in 800-1000 hp combo's. I lost power and my car slowed when I went from a conventional split pattern to a single pattern of similar specs. I can find no reason to believe that going further in that direction would yield a different result. I made my recommendation several pages ago based on my experience.
09-17-2010, 10:45 AM
#51
2. The other guy did dyno reverse-split and single-pattern cams and did document a significant loss in power with the reverse-split.
This is more data than ANYONE has supplied showing reverse-splits are better.
09-17-2010, 10:52 AM
#52
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1. When going from a conventional-split to a single-pattern, I lost power. Why on earth would I go further in that direction???
2. The other guy did dyno reverse-split and single-pattern cams and did document a significant loss in power with the reverse-split.
This is more data than ANYONE has supplied showing reverse-splits are better.
2. The other guy did dyno reverse-split and single-pattern cams and did document a significant loss in power with the reverse-split.
This is more data than ANYONE has supplied showing reverse-splits are better.
I made upwards to 1800 hp with a 366 with a reverse split AND could spool on the brake...I would almost guarantee (based on the data we gathered) that the car would not have spooled with a fwd split...not spooling a turbo makes for pretty lousy performance
also it made rediculous power at lower boost levels...how many cars with a 360ish motor do you know that will go mid 150s trap speeds at 8 psi when weighing 3500 lbs? I know many that won't even come close to that at 10+ psi
there was no magic in that setup either...was a hydraulic cam, 225cc headed motor...
Last edited by Fireball; 09-17-2010 at 10:59 AM.
09-17-2010, 10:59 AM
#53
I can say that between 4500 (converter flash) and 6200 rpm (shift point), the conventional split beat the single-pattern by 50 rwhp the whole way.
I have to wonder, though. . . you are claiming that the reverse-split has quicker spool but not more power. I can't see where the later EVO could help spool (likely the opposite is true) but I could see where reduced overlap would help when on the transbrake. In this case, it's not a reverse-split versus conventional-split debate, but more about more versus less overlap.
Mike
09-17-2010, 11:02 AM
#54
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I didn't time the spool-up on mine with either cam (and you didn't try it with a conventional-split) so neither of us have data on that. But, I can say that I never had a trans-brake or a 2-step and was happy with my spooling characteristics. I left off idle and reached my goals.
I can say that between 4500 (converter flash) and 6200 rpm (shift point), the conventional split beat the single-pattern by 50 rwhp the whole way.
I have to wonder, though. . . you are claiming that the reverse-split has quicker spool but not more power. I can't see where the later EVO could help spool (likely the opposite is true) but I could see where reduced overlap would help when on the transbrake. In this case, it's not a reverse-split versus conventional-split debate, but more about more versus less overlap.
Mike
I can say that between 4500 (converter flash) and 6200 rpm (shift point), the conventional split beat the single-pattern by 50 rwhp the whole way.
I have to wonder, though. . . you are claiming that the reverse-split has quicker spool but not more power. I can't see where the later EVO could help spool (likely the opposite is true) but I could see where reduced overlap would help when on the transbrake. In this case, it's not a reverse-split versus conventional-split debate, but more about more versus less overlap.
Mike
4500 converter flash is a loose converter that most resort to in order to compensate for bad spool characteristics. Try spooling something that goes to 2400-2500 on the brake
My new cam for my 388 will be spec'ed by shawn and I know it will provide outstanding performance...I'll leave it at that
09-17-2010, 12:56 PM
#55
So, by that, you are implying that the EVO event is THE difference that you say improves spool time? What is the theory behind holding the gas in the cylinder longer to increase heat delivered to the turbine?
The 4500 flash was at 17 psi boost. On the foot-brake, it would barely go over 2000.
The 4500 flash was at 17 psi boost. On the foot-brake, it would barely go over 2000.
09-17-2010, 01:38 PM
#57
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From what Im understanding, from most of this, conventional split will look better on a dyno sheet due to peak power being greater but a reverse split will pull throughout the RPMs.
09-17-2010, 02:06 PM
#58
Wow. This thread has gone off the deep end!!! I agree with Kurt/Jim/Brian/Shawn/Fran..........
A lot of the claims in this thread don't really help the OP much. The OP should contact one of these companies and have that company specify a cam (shelf or custom) that will allow the OP to get the most out of his combo. Some people want peak power, some want track performance, some want driveability. Tell them your intentions with the car and they will assist you in every way possible.
Good luck!
A lot of the claims in this thread don't really help the OP much. The OP should contact one of these companies and have that company specify a cam (shelf or custom) that will allow the OP to get the most out of his combo. Some people want peak power, some want track performance, some want driveability. Tell them your intentions with the car and they will assist you in every way possible.
Good luck!
