chpmnsws6

iTrader: (70)

RPM, not an issue, Intake, not an issue, Fuel, not an issue.... But exhaust, well, why does it not work to have a slightly restrictive exhaust manifold with a large camshaft like say..... the T-Rex or MS4? What will to much overlap cause on a restricted exhaust? For my application, the best header we have is a 1 5/8's shorty header with a 2 1/2 inch collector. Far less then ideal. What will overcamming the engine cause on this restrictive exhaust?

RoAdRaGe912

I don't think it's a question of overcamming, as much as it is just having a restrictive exhaust.

Far from being the expert, my understanding is that volumetric efficiency will fall off sooner and therefore you'll start losing hp sooner in the rpm band.

What I'm wondering is, even though the large overlap will cause more reversion at low rpms, will the smaller exhaust allow for better scavenging? If so, then basically you have shifted the entire power band lower in rpms.

I haven't done much reading on the exhaust side, so I'm looking forward to some elaboration on this.

LSwonderfull

If the exhaust system is inadequate than residual exhaust gases will pollute incoming intake charge and cause poor combustion which means less power and driveability.

Old SStroker

Perhaps you mean "improper camming" rather than "overcamming".

A cam should be tailored to the SPECFIC engine/vehicle/driver desires. One size definitly doesn't fit every combination well. Normally the "custom shelf" cams like you mentioned are meant to run with very free-flowing exhausts. If they were designed well, a certain primary size and collector length would be recommended. You should ask the cam provider what exhaust the cam was designed for.

If your exhaust system is restrictive, a good cam guy will give you the most you can get from what you have. You may not get all of the power that larger headers would allow, but you CAN get the most from what you have. Obviously the cam will be custom for your application.

Any valve timing different from the ideal for your setup will cost you performance. Determining the ideal valve timing is the problem. Choosing the right person to do the engine/cam design is Job One. In almost all cases, the car owner is the wrong person to do the cam. Hire a pro.

My $.02

Jon

ryan00z28camaro

iTrader: (7)

well put haha

chpmnsws6

iTrader: (70)

Everyone says hire a pro but how did that pro start out? I've already talked to a cam guru on here and think I have a grind made up (226/236 on a 110 LSA) but do not understand why more duration would be taking backward steps in terms of power

LSwonderfull

When your engine is restricted to a peak power rpm of around 6300 like the LS based efi intakes do , than adding too much duration to your cam can decrease your low to mid range power with out benefiting from the top end power that extra duration can add. I think this is the answer your looking for?

Old SStroker

Some start out by learning how an engine moves air. "Delta p" is the simple answer. Understanding how to take advantage of the delta p the engine creates is the big step. IMO, not everyone who specs cams does that or even really understands Delta p. You can bet you last nickel that the engine understands its own Delta p.

"If you want to go, hire a pro." Tacky little tag line, huh?


Jon

Ballistic Jello

Quote:

Originally Posted by Old SStroker

Some start out by learning how an engine moves air. "Delta p" is the simple answer. Understanding how to take advantage of the delta p the engine creates is the big step. IMO, not everyone who specs cams does that or even really understands Delta p. You can bet you last nickel that the engine understands its own Delta p.

"If you want to go, hire a pro." Tacky little tag line, huh?


Jon

So what's the best way to learn? College - Mechanical Engineering, Physics, Fluids?
Lots of books? All of the above?

chpmnsws6

iTrader: (70)

Thats one of the classes I didn't take.... Honestly (wanted to take High Perforemance Fuels but it was going to cut into the nursing program)

chpmnsws6

iTrader: (70)

That was the answer I was looking for

Old SStroker

Good start.

Perhaps NOT listening to much of the misinformation posted on internet forums is a good idea. How do you know what is good and what is bad information? There's the rub.

Ballistic Jello

Quote:

Originally Posted by Old SStroker

Good start.

Perhaps NOT listening to much of the misinformation posted on internet forums is a good idea. How do you know what is good and what is bad information? There's the rub.

Damn right. How did you learn? I believe that most of what you post is valid, though I certainly cannot be sure, and I'm curious how you learned so much.

BTW, as I read all of your posts I hear them in Burt Reynold's voice, with faint sounds of Jerry Reed in the background.

Old SStroker

Great screen name, BJ. Ottumwa is a great name for a small town. I picture you as a Radar O'Reilly lookalike.

LOL! I occasionally do radio and TV commercials for a liquor and wine store but I certainly don't sound much like Burt. I wish I looked like him! I probably resemble Fred more than Jerry or Burt.

I learned the hard way by studying automotive engineering MANY years ago and working for an OEM as an engineer in the early muscle car era. There were a lot of smart people I worked with and learned from. A lot of what I have learned in this century has come from my son who has a firm grasp of how engines work. I also learned a lot from Joe Mendelis, my son's best friend, who passed away in May at 26.

Reading and eventually understanding folks like Prof. Gordon Blair helps a lot. So does just being around since WWII! FWIW, my war was Vietnam when I was in my 20s. I was on the short hair and blue uniform side, not the long hair and tie dyed side, but that's probably obvious. I also think Sarah Palin is hot.

I have many of you hoodwinked into believing what I say. He-he-he! That's my power trip. Isn't the internet a wonderful place?

Seriously, if I am being facitious/subtle I paint with a broad brush. IOW, it should be obvious when I'm putting you on. I'm glad I can entertain you.

Did you get the quote form Hamlet? I'd rather read A. Conan Doyle than Shakespeare.

My siggy quotes four of my favorite people/characters and their views of life and how things work.

More than anyone wanted to know...


Jon

To keep this on topic, simplistic answers may not be the whole truth, OP, but they are comforting aren't they?

Sabre002

iTrader: (7)

I think you are "OVERTHINKING" this. An Engine is a air pump plan and simple. If you want to make HP you have to get air into it faster and more efficiently. There is a good article on header piping and Diameter in the new hot rod mag I think you should read and you might find out that you have to small of a header on your car. I went with a 1 7/8 head on my car and made a nice flat TQ curve with the cam I have and still made good HP up top for a stock head and intake car.

Ballistic Jello

Quote:

Originally Posted by Old SStroker

Great screen name, BJ. Ottumwa is a great name for a small town. I picture you as a Radar O'Reilly lookalike.

LOL! I occasionally do radio and TV commercials for a liquor and wine store but I certainly don't sound much like Burt. I wish I looked like him! I probably resemble Fred more than Jerry or Burt.

I learned the hard way by studying automotive engineering MANY years ago and working for an OEM as an engineer in the early muscle car era. There were a lot of smart people I worked with and learned from. A lot of what I have learned in this century has come from my son who has a firm grasp of how engines work. I also learned a lot from Joe Mendelis, my son's best friend, who passed away in May at 26.

Reading and eventually understanding folks like Prof. Gordon Blair helps a lot. So does just being around since WWII! FWIW, my war was Vietnam when I was in my 20s. I was on the short hair and blue uniform side, not the long hair and tie dyed side, but that's probably obvious. I also think Sarah Palin is hot.

I have many of you hoodwinked into believing what I say. He-he-he! That's my power trip. Isn't the internet a wonderful place?

Seriously, if I am being facitious/subtle I paint with a broad brush. IOW, it should be obvious when I'm putting you on. I'm glad I can entertain you.

Did you get the quote form Hamlet? I'd rather read A. Conan Doyle than Shakespeare.

My siggy quotes four of my favorite people/characters and their views of life and how things work.

More than anyone wanted to know...


Jon

To keep this on topic, simplistic answers may not be the whole truth, OP, but they are comforting aren't they?

"Did you get the quote form Hamlet? I'd rather read A. Conan Doyle than Shakespeare."



Swing and a miss. What quote? If I had quoted something I'd probably credit it. I'm a current-era military fiction lover, but lately Stephen Hunter has redefined "good book" to me. Hot Springs and Pale Horse Coming are untouchable. I'm about 6 inches taller and 40 lbs lighter than Radar at a guess, that was cold.

So, as a 20 year old car lover who is just developing some working knowlege, (timing chain replacement on truck in sig, very frustating) what path of higher learning would you suggest I take in order to obtain a job somewhere in the late model performance industry, i.e. a Speed Inc. or maybe Katech caliber employer if not a manufacturer in Detroit? Are there good schools for automotive engineering? I've already wasted 10 months at a (good) local community college for automotive technology and learned a lot of bullshit and a little helpful knowledge for a starting mechanic, which I am not sure about doing. My plan for the last year or so has been to complete the CNC machining program at same college and after a couple years of experience and rolling in piles of greenbacks to seek a job in engine machining, but I've never been confident this is a realistic plan.

Oh, off-topic, but do you know if it's possible to obtain "Sailor Jerry" in Iowa? Your cylinder head analogy from another post has piqued my interest.

Old SStroker

Time to get back OT?

66deuce

iTrader: (1)

i think the OP is restricted to a 1 5/8 header,probably class rules at a race track or something..
of course,like SStroker already said,you could do better with a bigger header..but if this is not an option,then a custom cam is in order to maximize the power with the package he's limited to..a little longer exhaust duration(to a point)and more importantly the proper valve timing will help to "crutch" a restrictive exhaust..but there is a point to where you get diminishing returns..

66deuce

iTrader: (1)

yes,it is an air pump..but the air pump we are talking about is an "internal combustion air pump". not as simple as one might think..

chpmnsws6

iTrader: (70)

Room is the restriction. So far all they've been able to fit in these cars are 1 5/8's inch shorty headers, but they are working on larger headers hopefully. I will not be buying a conversion kit until someone makes good header for it.