Thorley THY-312 Headers install on W series

[jcgribks]

Should have said I already have UltraPower Magnum wires and AC Iridium spark plugs to install when it gets warmer to install my Banks headers.

[Daveinet]

After my previous RV, everything else is just going to be disappointing. But I am pleased with the UltraPower and glad I purchased it. It just makes it seem to drive what "normal" should look like. Its nice to finally have enough power to stay in overdrive towing my Jeep. It downshifts when it should, but like I said, its nice to drive normal. I still have yet to swap out to Magnaflow mufflers on this one. I'm thinking that will be another layer of nice.

[Joeniceguy]

one morre suggestion. On myearlier morothome i replaced the intake manifold and it makes a world of power. I used a monifold for low rpm like off idle to 4000. I have done that on several gassers and it really works

[Daveinet]

Originally Posted by Joeniceguy

one morre suggestion. On myearlier morothome i replaced the intake manifold and it makes a world of power. I used a monifold for low rpm like off idle to 4000. I have done that on several gassers and it really works

Did you find that to be true compared to modern intakes with long runners? If so, I'd be surprised, as modern intake technology is highly matured. Most are tuned for low end grunt so they can turn the motor slow get fuel mileage. The second generation after port injection showed a significant understanding of how intakes work. Prior to port injection, the intake design was limited by wet runners. If the air moved too slowly or too much distance, the fuel would fall out of the air and puddle. With port injection, that doesn't happen, which allowed for significant development in runner design. Pretty much once you get to the 8.1, the design had matured. So that is the context of my question. Unless you go to a plastic intake with the variable size runners, I'm not sure where the improvement could come from.

[Davel]

Saddlesore, thanks for the heads up on the wiring, that would be easy to overlook. I have had Ultrapower since 2005 and have been very pleased with it. The throttle response and added torque in cruise at 2100 rpm is great!
Dave

[Wayneq85]

My first MH was 72 Winebago with Dodge 440 and cast iron exhaust. Cast iron was burned out and brittle. They were still available bit super expensive.
Doug Thorley headers were less than one cast manifold.
Headers fit perfectly. Was able to install laying on ground. Only had to remove starter. Drove to shop with open pipes to get exhaust system completed.
My biggest fear was getting out the bolts. Soaked in solvent for three days. All came out easily.
Good luck

[EyezOpen]

Originally Posted by Daveinet

Did you find that to be true compared to modern intakes with long runners? If so, I'd be surprised, as modern intake technology is highly matured. Most are tuned for low end grunt so they can turn the motor slow get fuel mileage. The second generation after port injection showed a significant understanding of how intakes work. Prior to port injection, the intake design was limited by wet runners. If the air moved too slowly or too much distance, the fuel would fall out of the air and puddle. With port injection, that doesn't happen, which allowed for significant development in runner design. Pretty much once you get to the 8.1, the design had matured. So that is the context of my question. Unless you go to a plastic intake with the variable size runners, I'm not sure where the improvement could come from.

This can be a touchy subject, over the yrs the auto industry and the after market industry has let's say blown things out of proportion.

It is now fairly well known recurving ignition timing and trimming fuel delivery produces results that are simply overwhelming..well kinda that is

It is a very easy task for the old carbed/HEI systems of yesterday, the intergration of fuel&ignition into one product called EFI makes the task quite expensive for the average Joe.

Dual plane intakes, long runners/short runners, have little effect on a engine with a dumbed down/retarded ignition system. Even in tuned engines they have little effect under 5000 rpm.

To the point of this thread headers merely dump the by products of combustion both heat and hydrocarbons far more efficiently. Does that make a difference? A smidge in a factory tuned engines, in a retuned engine it may result into quite a bit

Headers dump exhaust heat,big blocks have quite a bit of that. Take a look at school busses exhaust some time, there huge and mostly straight. Those exhaust systems are dumping high volumes of heat. That heat is due to very very late timing, so late the left over exhaust gases reignite in the exhust system and complete the combustion process. Now that is a lot of energy going right down the pipe so to speak..Ohh and heat...heat that is no longer trapped in a choked down factory exhaust.

[TheCatsRV]

Originally Posted by EyezOpen

Headers dump exhaust heat,big blocks have quite a bit of that. Take a look at school busses exhaust some time, there huge and mostly straight. Those exhaust systems are dumping high volumes of heat. That heat is due to very very late timing, so late the left over exhaust gases reignite in the exhust system and complete the combustion process.

Suspect the retard in timing may be due to variable engine loads and the desire by the auto manufacturers not wanting to warranty grenaded engines. Maybe knock sensors shouldn't be relied on for that purpose.


Doesn't help that trucks are exempt from CAFE standards.

[Daveinet]

Originally Posted by EyezOpen

This can be a touchy subject, over the yrs the auto industry and the after market industry has let's say blown things out of proportion.
....

Dual plane intakes, long runners/short runners, have little effect on a engine with a dumbed down/retarded ignition system. Even in tuned engines they have little effect under 5000 rpm...

Dual plane intakes are very different from long runners and really don't belong in the same discussion. Prior to port injection, intakes were limited because the fuel would fall out of the air. Port injection means the intake is dry, so there is no limit to the intake length. Curves are OK, because centrifugal force does not fling the fuel to the outside of the curve. So now you have long runners that are specifically tuned for low RPM.

When I designed and tuned my 502 in my previous motorhome I used a desktop dyno to understand what the intake would do. The software accurately predicted the torque curve for the stock engine (compared to the factory dyno tests). I was able to change the intake runner length and see what difference it made on the torque curve. Based on the software I modified the intake runner length. Test results showed it to compare very close to the predicted torque improvements in the 2800-3000 RPM. There was a big bump in mid-range power, due to the intake design change. This could also be seen in the cylinder pressure. As I created the timing curve, I found that I did not need to take any timing out for wide open throttle below 3000 RPM. Once I hit 3000 RPM, then I needed a lot of retard. There was no "curve", but rather an abrupt change, indicating much greater flow. I could have tuned the intake for a lower RPM, but then I was sacrificing too much at 5000 RPM. With a dry intake, you can tune it to any RPM. That is just math and physics. The old days just had limits dues to wet runners.

Intake design is a very interesting discussion. There are 3 aspects to the design. First is to have a long runner, so there is mass to keep the air moving down the runner. The second aspect is the pressure wave created by the valve that returns up the intake. The idea of this is so the pressure wave goes up the intake and bounces back down to create pressure just as the valve opens. This is refereed to as "Ram Air effect". (Ram Air is NOT catching air from driving down the road. That doesn't work at the speeds we drive) Lastly is in some intakes, you can time the valve pressure wave from another cylinder to send pressure to another cylinder directly in line. Its surprising to think about how much affect the motion of the valve results in pumping action, pressurizing air into the cylinder. This is why you can have an intake volumetric efficiency above 100% without a turbo or blower. It also why engines tend to run like crap when you floor them at low RPMs. In most engines the pumping action doesn't work till you hit about 1500 RPM.

It is a very easy task for the old carbed/HEI systems of yesterday, the integration of fuel & ignition into one product called EFI makes the task quite expensive for the average Joe.

No, it just takes a lot more studying. The information is out there and its fairly cheap. There are some GM ECMs that are well documented on the net. Readers and burners these days are dirt cheap. Software is free, donationware. It took me about a year before I really understood it. As a DIYer, one thinks they understand how engines work until you begin programing. Then you realize you don't know squat. Actually you know a lot, but you don't understand it like you think you do - at least that was the case for myself. A lot of reading and time for it to settle in.

[1turbofocus]

Originally Posted by TheCatsRV

Suspect the retard in timing may be due to variable engine loads and the desire by the auto manufacturers not wanting to warranty grenaded engines. Maybe knock sensors shouldn't be relied on for that purpose.


Doesn't help that trucks are exempt from CAFE standards.

I do Custom Tuning , I make my own Tuning Files through SCT and HPT , A lot of people dont know but the KS = Knock Sensor can Advance Timing if no Knock is Detected as well as retard Timing if Knock is Detected

Tom

[TheCatsRV]

Originally Posted by 1turbofocus

I do Custom Tuning , I make my own Tuning Files through SCT and HPT , A lot of people dont know but the KS = Knock Sensor can Advance Timing if no Knock is Detected as well as retard Timing if Knock is Detected

So a programmed ECM can set advance until it detects detonation? I'm just a bit leery of allowing any. I'm not sure what amount is tolerable.

I keep thinking about that person who managed to blow the crank and a couple of pistons out of a 502 (he posted pics - can't find the post). I was looking to buy a Workhorse chassis Newmar that suffered similar but that was apparently an engine assembly fault which the manufacturer (either GM or Workhorse) covered.

[EyezOpen]

Originally Posted by Daveinet

Dual plane intakes are very different from long runners and really don't belong in the same discussion. Prior to port injection, intakes were limited because the fuel would fall out of the air. Port injection means the intake is dry, so there is no limit to the intake length. Curves are OK, because centrifugal force does not fling the fuel to the outside of the curve. So now you have long runners that are specifically tuned for low RPM.

When I designed and tuned my 502 in my previous motorhome I used a desktop dyno to understand what the intake would do. The software accurately predicted the torque curve for the stock engine (compared to the factory dyno tests). I was able to change the intake runner length and see what difference it made on the torque curve. Based on the software I modified the intake runner length. Test results showed it to compare very close to the predicted torque improvements in the 2800-3000 RPM. There was a big bump in mid-range power, due to the intake design change. This could also be seen in the cylinder pressure. As I created the timing curve, I found that I did not need to take any timing out for wide open throttle below 3000 RPM. Once I hit 3000 RPM, then I needed a lot of retard. There was no "curve", but rather an abrupt change, indicating much greater flow. I could have tuned the intake for a lower RPM, but then I was sacrificing too much at 5000 RPM. With a dry intake, you can tune it to any RPM. That is just math and physics. The old days just had limits dues to wet runners.

Intake design is a very interesting discussion. There are 3 aspects to the design. First is to have a long runner, so there is mass to keep the air moving down the runner. The second aspect is the pressure wave created by the valve that returns up the intake. The idea of this is so the pressure wave goes up the intake and bounces back down to create pressure just as the valve opens. This is refereed to as "Ram Air effect". (Ram Air is NOT catching air from driving down the road. That doesn't work at the speeds we drive) Lastly is in some intakes, you can time the valve pressure wave from another cylinder to send pressure to another cylinder directly in line. Its surprising to think about how much affect the motion of the valve results in pumping action, pressurizing air into the cylinder. This is why you can have an intake volumetric efficiency above 100% without a turbo or blower. It also why engines tend to run like crap when you floor them at low RPMs. In most engines the pumping action doesn't work till you hit about 1500 RPM.

No, it just takes a lot more studying. The information is out there and its fairly cheap. There are some GM ECMs that are well documented on the net. Readers and burners these days are dirt cheap. Software is free, donationware. It took me about a year before I really understood it. As a DIYer, one thinks they understand how engines work until you begin programing. Then you realize you don't know squat. Actually you know a lot, but you don't understand it like you think you do - at least that was the case for myself. A lot of reading and time for it to settle in.

I should have been far more specific, namely 454 big blocks, low comprehension (7.5) smog motors.

Changing the timing curves to create cylinder pressure also know as tourqe and horsepower. Some say throttle response.

Overly simplified..The Combustion Process. Also called a tuneup.

My own perception of your very well articulated commentary would be the induction process. While interrelated they both are distinctly different to me.

To the interrelated part, a rich mixture responds best to retarded timing a lien mixture responds best to advanced timing. The induction process meters the fuel and delivery...the spark timing detonates the end process of the induction cycle.

[Daveinet]

Just for fun, one of the very unorthodox things I did is added additional runner length tubes above the throttle plate. I ran it that way for 9 years. Some of the plastic cracked, so before I sold it, I changed back to a K & N round air cleaner with the filter on the lid and sides. This should have had plenty of flow capability. The engine lost a lot of top end and ran rich everywhere, even at part throttle. You could see the MAP drop as you got to 4000 RPM and above. So I switched back to the tubes. It was kind of weird, as it created a small amount of "turbo lag" feel. It was as if it took time for the air to get moving, but once it did, in semi steady state, the power increased. It also made it chirp the tires between first and second. It would not do that with the conventional air cleaner just above the throttle plate.

[1turbofocus]

Originally Posted by TheCatsRV

So a programmed ECM can set advance until it detects detonation? I'm just a bit leery of allowing any. I'm not sure what amount is tolerable.

Correct , I can adjust how much timing gets added if no knock is detected , Change how fast the timing is pulled when knock is detected , How fast timing gets added in , what RPM its all allowed to do it at and much much more

Tom