Best mods for budget
05-03-2006, 08:21 AM
#21
Originally Posted by steve2001sh
Similar, yes, but my point is to determine whether you are serious enough to spend the extra money to get very little in gains, such as with ceremic coating (that is if you believe it produces more HP at all). Many people would do just fine with the cheaper ones.
I intend to try to make my comparison somewhat valid, though not scientific. For starters, I will only look at dynojet numbers. I understand there will be other variations, but I'm only trying to provide a general estimate.
The point is not to aim for a specific HP, but to show a good way to get to each level and the price involved. I am not using ETs, because those will matter less to the autocross people. I'm not including things like transmission or suspension, because the topic I'm trying to cover is complicated enough to start with.
This is not exactly true. That "5th" cycle is to replace the last bit of exhaust with clean air. A 10:1 350 ci engine will displace 350 ci per cycle (2 rotations). If you manage to replace 100% of the displacement with clean air, that is what we refer to as a VE of 100. The trick with scavenging is that 35 ci of exhaust left sitting in the heads. If you can manage to get that out too, it would be like having a 385 ci engine. Additionally, some of the limiting factors of how much boost you can run are heat and turbulance. If you have a restricting intake and exhaust, your turbo will have to work harder to cram all that air in there, thus heating it, making it more turbulant, and reducing the max boost you can run without detonation.
I intend to try to make my comparison somewhat valid, though not scientific. For starters, I will only look at dynojet numbers. I understand there will be other variations, but I'm only trying to provide a general estimate.
The point is not to aim for a specific HP, but to show a good way to get to each level and the price involved. I am not using ETs, because those will matter less to the autocross people. I'm not including things like transmission or suspension, because the topic I'm trying to cover is complicated enough to start with.
This is not exactly true. That "5th" cycle is to replace the last bit of exhaust with clean air. A 10:1 350 ci engine will displace 350 ci per cycle (2 rotations). If you manage to replace 100% of the displacement with clean air, that is what we refer to as a VE of 100. The trick with scavenging is that 35 ci of exhaust left sitting in the heads. If you can manage to get that out too, it would be like having a 385 ci engine. Additionally, some of the limiting factors of how much boost you can run are heat and turbulance. If you have a restricting intake and exhaust, your turbo will have to work harder to cram all that air in there, thus heating it, making it more turbulant, and reducing the max boost you can run without detonation.
headers are headers in most situations, i would say there may be 2-4 hp at the most between kooks and pacesetter. i may be wrong but the performance is going to be almost the same, you just pay more for a longer lasting header, not really a better performing one.
05-10-2006, 06:33 PM
#22
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Originally Posted by 300bhp/ton
That's it exactly.
I mean we all must have sat down at one time or another and generated a list of bolt on's we'd like to get and add up how much advertised HP gain we should see, but the numbers just don't add up.
A typical M6 Fbody should lay down 290-300rwhp SAE on a Mustang Dyno (I use Mustang as it closer represents SAE Net figures quoted by manufacturers).
However the most you are likely to see from a bolt on car is 350-360rwhp so a gain of typically 50bhp.
But when you add up the potential gains something doesn't add up, e.g.
All these numbers I have seen advertised as genuine bhp increases per mod (over stock
)
-lid or induction kit = 15rwhp
-headers = 20rwhp
-catback = 12rwhp
-K&N filter = 2rwhp
-Ported TB = 8rwhp
-LS6 intake manifold = 20rwhp
-!CATS = 10rwhp
This short list already totals 87bhp which would mean our car should be making 377-387rwhp way above what people really achieve and we haven't even considered pulleys, electric water pump, lightweight flywheel, lightweight driveshafts and wheels or a tune.
So the only logical conclusion I can think of is that of diminishing returns, however if someone else has an alternative idea I'd love to hear it.
I mean we all must have sat down at one time or another and generated a list of bolt on's we'd like to get and add up how much advertised HP gain we should see, but the numbers just don't add up.
A typical M6 Fbody should lay down 290-300rwhp SAE on a Mustang Dyno (I use Mustang as it closer represents SAE Net figures quoted by manufacturers).
However the most you are likely to see from a bolt on car is 350-360rwhp so a gain of typically 50bhp.
But when you add up the potential gains something doesn't add up, e.g.
All these numbers I have seen advertised as genuine bhp increases per mod (over stock
)-lid or induction kit = 15rwhp
-headers = 20rwhp
-catback = 12rwhp
-K&N filter = 2rwhp
-Ported TB = 8rwhp
-LS6 intake manifold = 20rwhp
-!CATS = 10rwhp
This short list already totals 87bhp which would mean our car should be making 377-387rwhp way above what people really achieve and we haven't even considered pulleys, electric water pump, lightweight flywheel, lightweight driveshafts and wheels or a tune.
So the only logical conclusion I can think of is that of diminishing returns, however if someone else has an alternative idea I'd love to hear it.
They're bull_ _ _ _ !
At the track, and seat of the pants numbers, from what I've figured out.
Take advertised numbers and multiply by about 50%. Those are realistic gains.
"Advertised" numbers most likely come from things like bolt ons on a car with a HUGE heads/cam package. Or, comparing dyno pulls taking the worst "baseline" and comparing it to the best dyno pull afterwards.
But, "diminished gains" still doesn't make sense to me. An engine is basically an air pump. The more air it needs (from making more power) the more of a RESTRICTION certain things become.
All of the bolt ons on the intake side or exhaust side become more of a restriction as you make more power.
