Are headers worth it???? (1 Viewer)

[IDave]

Actually, I hope this isn't a complete hijack, and that we are helping answer the original questions in a "this way, and here's why" manner. :-\

Incomplete combustion would occur when there is not enough oxygen coming in to oxidize all of the fuel that is coming in. At idle, this is controlled at the carb idle mixture screw. Turning it in reduces the amount of fuel making the mixture relatively leaner. Fuel in excess of available oxygen goes through unburned. During driving, the mixture is controlled by the jets, which by their size determine the amount of fuel mixing with the oxygen available. At higher elevations, there is less oxygen in the air, so changing to smaller diameter jets reduces the amount of fuel, matching the available oxygen better. At higher temperatures, the air oxygen molecules are farther apart, so you have less oxygen in a given volume of air, and that, too, would result in relatively incomplete combustion.

At least, that is how I understand it at this point. I want to learn more, too!

 

[Poser]

So,

There would not be any advantage to going to a hotter spark, in aiding in combustion, burning fuel, and making power?

 

[IDave]

Either it is sparking or not. More current might overcome a badly insulated wire that was only igniting the sparkplug intermittantly. Or a badly fouled plug might be overcome by more current. But it is the chain reaction that burns most of the fuel. The spark only initiates it.

 

[Poser]

Ok,

So where does the performance increase that not only me, but apparently many have gained, going to not only the DUI set up, but electronic/HEI uints, not just in Land Cruiser sixes, but many other applications?

Something is not adding up... ???


Of course, I could just be retarded.. :-*

-Steve

 

[IDave]

I'd like to know that, too. This site http://www.off-roadweb.com/tech/0202or_engine/, for instance, states an "additional 45 horsepower" to the Chrysler small block V8. All I can think of is that a regular distributor must misspark intermittantly, whereas DUI does not.

 

[Pin_Head]

It says "up to" 45 hp. There may be some truth, but some is hype. OEM distributors have an advance curve that is designed to meet smog requirements, so the advance isn't optimum for hp. You can achieve the same thing by optimizing the advance curve on any distributor.

As someone who dropped a lot of money on performance modifications, I always wanted to believe that I was getting more performance for my money, but my ETs said otherwise.

On topic. Headers can give a noticable increase in hp, especially when they are uncapped.

 

[IDave]

Ummm....

 

[Rice]

One additional point is that running HEI (or the like) ignition systems allows for a larger spark gap. While this does very little for an engine in the high RPM range I have heard of dyno results that show moderate (read small) increases in low RPM torque readings. I have to say, however, the only reason I run an aftermarket system (MSD) is to help with cold starts, hot starts, timing accuracy, and so I could install it and forget about it ... not because I thought I was getting a performance boost.

If, in fact, I calculated my horsepower based on the "advertised" increase given by everything in my engine I think it would have to be close to 900 ("look Mom, and with no turbo!!!). Better for me to stick with the dyno numbers!

 

[Perfect Obsession]

[quote author=IDave link=board=1;threadid=8866;start=msg77600#msg77600 date=1071802872]
...McCall is cold right now. 10 degrees F in morning, 20 degrees F late afternoon. In the summer, 40 degrees morning, 70-80 degrees afternoon.
[/quote]

Bonjour Idave,

Therefore, McCall temperatures are similar to Trois-Rivières.

Yes, you understand my calorific propagation explanations. Your engine has headers and liquid heat riser. Fantastico! You have the option to directly or indirectly control the liquid heat riser.

- Indirectly, since your thermostat stabilize the manifold temperature near the engine operating temperature, which is certainly lower than near exhaust temperature.

- Directly, since you could add a specific thermostat that close the circuit when the liquid reach targetted temperature. That's concept is similar to the air path's "a" paragraph, except it's applied to the "d" paragraph.

In both case, when cold, you heat it up; when hot, you regulate. In your case, indirect control don't cost you a penny, it's regulated. Just apply insulation and fresh air breather, IMHO, you'll have best efficiency for money.

Warning: I talk about "snorkel" as fresh air breather since you are limiting the amount of dust, slush (in rust belt area), water and moisture (that obstruct paper filter) breath into the intake, and you are breathing colder air on paved road or desert road in summer

Concerning the distributor (out of thread but ...), I would specify that internal combustion engine ignition versus power could be a thread by itself. Here are some ignition parameters, from the piston and A/F mixture point-of-view, not the after-market marketer.
- When the spark plug sparks
- The spark plug's temperature
- How long the spark plug sparks
- Where is the spark plug, relative to cylinder geometry
- What is the "flame" propagation speed
- How travel the "flame" propagation shock wave and reverberation, relative to the cylinder geometry (which is relative to piston's position, speed and acceleration !!!)
- How was the A/F mixture's scanvenging and swirl before ... (intake/exhaust valve timings and manifold geometries, ...)
- And some others that I missed ...

Therefore, each engine ignition is specific. Period !

 

[Gumby]

For whatever the reason my HEI on my 2F did have a noticable increase in power. It also had better cold start and better high RPM performance. Also the HEI is a huge asset in reliability. When it does break, the parts are available at Wal-Mart in a pinch. Try finding a Toyota igniter on a sunday in the boonies.

In comparison, headers have a negligble effect on HP and torque and decrease reliability. They can add to cold start issues and carb icing issues as well. While it is true that you need to get the gasses out to get more in, it is not much of an improvement without improvements in other places. Also, the stock manifold, while it is restrictive, is appropriate for a motor that never sees RPM ranges above 3000.

Stock 2F with stock intake, cam, heads and compression? Headers are not worth it unless you already have an exhaust problem.

csb in a cruiser - definately not worth it just for the reliability issues. Ram's horns work great for the RPM range we use.

Just my humble not-so-scientific opinion

 

[Perfect Obsession]

Sounds good for me Gumby.

Here is a link for those who likes performance and technical papers.

P.S.: Gumby, what is a "VJ-40"? Is it a virtual engine? ???

 

[Gumby]

V-8 J-40