Bluegrass, that's great info. I was under the incorrect impression that all engines had a small amount of overlap, but this was based on my brain and not anything that I knew for fact.

And I was completely unaware that a non-overlap cam was good for blown apps, or that there was such a thing. But I'm not too well-versed on cam timing schemes. Again, great info.

I guess the beauty of variable valve timing schemes is that you can get the best of both worlds... Plus some of the better setups vary lift as well as timing...way too complex for me

 

Me too!!!

I can't even buy an aftermarket cam with out plugging it into the PC Dyno on what ever vehicle I am thinking about buying it for and running Virtual track times to see which cam will get me where I want it to be best. Thank god for computers, before them I was just buying and hoping it was the best cam for my set up. Though perfomance gains were usally noticed, it likely wasn't the best cam I could have bought if I would have had the knowledge.

 

I have not saw the inside of a stock muffler but suspect it's large size holds extra track length to reduce the rpm where torque is improved as well as an oppertunity to make it very quiet.
Going to a smaller case takes way this longer track length thus a loss of low end torque is felt.
Anyone know what the internal configuration is?
The aftermarket mufflers do there designed job of improved gas flow but in this truck application seem not to be what you want because it's not helpful except in the higher rpm range where normal losses are higher on any exhaust system from the factory.
The air intake changes are in the same vein. Low rpm operation, there is no losses to make any effect because the throttle body is in sole control of airflow. At this point the stock air filter offers no restiction as long as it has not acumulated dirt restriction so much, that airflow becomes that restricted.

 

I can probabley let you know something on the stock mufflers next month...I think I found somebody capable of making the headers that I want the way I want them and I should have the money next month to have them made and replace the exhaust.

BUT I have not setteled on the design completey because it would prevent me from installing tubo later and I can't decide if I want turbo or supercharged.
I wish they had an electric version of abnormal asperation! HMMM... Let me think on that thought some more.

Bluegrass you inspire me so much it makes my brain hurt...

 

PASS, I think I might irritate a few on these boards with deeper tech but that is the point I come.
I know the older EEC fairly well and run a super charged Speed Density 5L with a Kenne Bell and a 540 hp 351w powered sprint car.
As you know, Iam against changing air intake systems and exhaust on a 'STOCK' truck because there is very little performance to be gained for the very high total cost.
All one has to do is go to the Kenne Bell site and do some reading to have this varified by a man and his company in the business for more than 35 years, and has no reason to be biased for or against because he does not sell but only parts that have power value on his blower kits.
Your charging is the way to go for large gains.
My opinion is unless the truck is light, a positive displacemnt type blower would be much nicer on the street right off idle.
There is a lot more to my story but i'm not here to give my lifes history other than to say lots of experience in the performance area and a moderator on another board.

 

You guys sound like you up for giving some more sound advice....I'm getting a rear magnaflow exhaust system tomorrow and I've read that having a muffler on each tailpipe doen't increase performance......does it decrease it....I think he was going to go from the si/do so it's not a true dual...a friend said I would have to have an x pipe to balance it out....and the installer said he could do something where he would switch the driverside pipe with a pass. side muffler something about crossing tailpipes to balance out the system....but he said I wouldn't notice a substantal gain as appose to the other way? This is going to cost me 450 of my hard earned dollar bills....Would 2 mufflers be 2 loud....I don't want cabin drone!!

 

I am not sure that I understand for sure or not...Are you just going to replace the stock mufler with a dual outlet muffler? Or are you cutting the cross pipe out and runing a cat back? With a dual out muffler you dont need an X pipe of H pipe either one. With a cat back I could be wrong please forgive me if I am but I am not sure that you have to have either of them either, it is nice but I don't think it is mandatory to have.
Now I have seen cat backs with dual in and dual out mufflers...I don't know about them what the positives or negatives are with them, maybe Bluegrass can help us out with that.

I have one for you too Bluegrass, I would like to hear as many opinions and if it's from some one else with experince thats all the much better. I have always ran modified asphalt and dirt. Of cd be wrong please forgive me if I am but I am not sure that you have to have either of them either, it is nice but I don't think it is mandatory to have.
Now I have seen cat backs with dual in and dual out mufflers...I don't know about them what the positives or negatives are with them, maybe Bluegrass can help us out with that.

I have one for you too Bluegrass, I would like to hear as many opinions and if it's from some one else with experince thats all the much better. I have always ran modified asphalt and dirt. Of course NASCAR we have to run N/A. So this is my first experince designing and planing forced induction system. I've been talking to some Porsche guys when I started sponsoring thier SCAA car and they have helped me undersatnd it a lot better. I' am building my truck as tribute to the old days Street/Strip. You know a dailey driver that gets driven to the track. You just don't see it much anymore and I'm slightly nostalgic.

Anyway back to the question... I'd like to confirm from another source. If I should beable to run 20 PSIourse NASCAR we have to run N/A. So this is my first experince designing and planing forced induction system. I've been talking to some Porsche guys when I started sponsoring thier SCAA car and they have helped me undersatnd it a lot better. I' am building my truck as tribute to the old days Street/Strip. You know a dailey driver that gets driven to the track. You just don't see it much anymore and I'm slightly nostalgic.

Anyway back to the question... I'd like to confirm from another source. If I should beable to run 20 PSI with a 10:1 compression ratio on pump gas? Expected redline is said to going to be around 6500 rpm. Then a second question...What system would you suggest to give the most constant pass ET's? I'll pay 1k-1.5k more and give up posiably higher maximum ET's for .25 Sec +/- consistancey.

 

So with all this said. I keep hearing, its more beneficial to keep the stock muffler than to replace it with a flow master.

But then here is the scenario.

I am NOT going to get any piping etc done on it.

So is it in my favor to replace the exhaust? And run the K&N. Or replace the muffler and keep the stock filter.

I am trying to get somewhat better gas if that possible at eh same time some performance.

So I heard that I will gain no performance.

I heard from someone else that I'll get better gas and performance but another said with the increased air flow, means more air through the air filter, which means it'l be wasting more gas as the computer is trying to compensate for the extra flow.

So bottom line, if just the muffler is changed, will I see any benefit other than sound....

Thx

 

BB, would you consider this as far as fuel milage goes?
No matter how much intake filter flow capacity you install, even no filter at all, the throttle body is in sole control of how much air is let into the engine at less than wide open throttle.
Just can't get past that as fact.

 

so in other words buddy? I see your point but vaguely...

 

He means that the air filter has nothing to do with how much air is coming into your combustion chambers. "EXCEPT" when the throttle is floored, at which time the throttle body is wide open trying to get as much air as it is allowed to have. The rest of the time it is restricting or allowing the air flow to your engine in various increments depending up on how much throttle you are giveing it. Daily driving your foot is in full control of the air flow that your engine intakes, not the air filter!

 

How ever....The exhaust system on the other hand is a different story! It decides how much air is allowed to leave the combustion chambers. Back pressure essentialy is a term describing how much pressure is pushing the pistons back down by the exhaust gases on the exhaust stroke. For every ounce of "backpressure" that is applied it is going to require that much more HP from the other cylinders to get the piston pushed up and the exhuast out. Back presure always increases with RPM's. Adding or removing backpressure alters where in the RPM range that peak performance lands. The closer you can get the peak performance output to the same place as the common rpm range that your engine ussally spends it's time in. That is where you gain gas milage and will seem like you have more HP becuse it is there when you neer every ounce of "backpressure" that is applied it is going to require that much more HP from the other cylinders to get the piston pushed up and the exhuast out. Back presure always increases with RPM's. Adding or removing backpressure alters where in the RPM range that peak performance lands. The closer you can get the peak performance output to the same place as the common rpm range that your engine ussally spends it's time in. That is where you gain gas milage and will seem like you have more HP becuse it is there when you need it. Driving styles and common driving conditions will dertermine which system is best.
That is just my own opinion based on my own experinces, I do not have any documented stats to back it up.

 

BTW...If you would like tangiable proof of where your engine is spending most of its time you can get a "carchip" by "DriveRight" at Auto Zone or I think JC Whitney carries them too. It is an OBDII log system. It comes with the Chip for your car that plugs in to the port under the steering wheel, the software for your computer and the data cable to plug it into you PC after it has aquired data logs from your car. After a couple weeks of normal driving you can pull the logs and view in graph form on screen or print them out that shows exactley how you normally drive and what your expecting your vehicle to do.

 

Sorry for all thesde post but if I put them all in one the board will mix up the post like it did on the second one...I hope you can decipher it.

BUT..I encourage you to keep in mind that all the money you might spend on new exhaust sytem, OBDII log system, etc, etc. When it's all done and you haveacheived maximum gas mileage. If that is the only reason for doing it all then how long will it take before you saved enough in gas to pay for the upgrades?

 

There are two basic things to keep in mind.
The exhaust flow is never more than the intake flow volume at any time.
The only difference is the temperature and speed of the exhaust flow is changed by the combustion events.
At low rpm and small throttle openings, the exhaust system's ability to flow is far more than needed before losses and pressure is of concern.
It is easy to prove this by installing a fitting before the cats and a small length of cooling pipe to get a vacuum gage into with a hose so you can see it as you drive. The gage would register in the positive direction instead of vacuum direction.
Anything above 2 psi at anytime is showing a fair amount of restriction in the cats or wherever it is occurring.