Ok, so I've been searching and thinking and searching and thinking some more.

this is where I am right now.

so the stock eaton is a constant displacement supercharger or whatever you want to call it, meaning for each single complete rotation of the rotors, a given amount of air X is moved or displaced into the engine right?

So at any given RPM (use engine or blower rpm since they are both directly linked) the blower will only move X times RPM amount of air right?

this means that no matter what you do to the intake ports or cam lift/duration or valve size, at any given RPM, the blower will still only move the same amount of air into the engine.

you can open the ports up as large as you like, put in the biggest valves, and open the valves (via cam lobes) for as long or as high lift as you want, but the blower will still be putting the same EXACT amount of air into that cylinder.

So now you have big ports that are actually slowing down the VELOCITY of that air charge. and you may actually be reducing volumetric efficiency.

This would explain why many people complain of lackluster or just plain non-existant gains from aftermarket cam and ported head mods.

To further complicate things, if you go with a wild cam and have overlap, you are now just dumping that air charge out the exhaust port instead of filling the cylinder.

Please before everybody starts screaming about KB or WORKS both of which can obviously flow more air, I'm discussing the stock eaton.

*************************************************
Now, on the other hand, if I port my heads and make them able to flow more air, do I now have less resistance and thus LOWER BOOST PRESSURE from the same combo (ex: 6lb lower)? Is this now MORE EFFICIENT? Is there less heat being created because of less boost pressure? If so, can I now change over to a larger pulley (#8 or #10) and then take advantage of the larger airflow capabilities of the ported heads or larger cams???
*************************************************

just thinking out loud here guys, but I welcome all additional input or thoughts on this.


thanks.

later,
chris

 

Superfords,

Yep, your thinking is right on. To many people get caught up in boost numbers and really it is about the effeciency of a motor and its ability to pump air in and out. A good example is my buddies mustang....he spent a lot of time picking the right parts and having some serious porting done etc. With 9lbs of boost from a Vortech, the car did 128 in the 1/4! My old mustang had 12psi and I was nowhere near him (like 116 MPH with stock ported heads, etc.). In any case, yes, you can up the boost up to a certain point on these eatons if you make changes like heads/cams, etc. but at some point the eaton blower becomes ineffecient and starts making a lot of heat. Tho heads/cams, etc are a good thing, its all about taking advantage of them to make more power (which you know already I think).

Tom

 

Your logic sounds right.

I have aftermarket cams with a stock Eaton and picked up some hp. Now, in my case, I lost some on the bottom end, but gained on the top end. Which is okay with me considering all the wheel spin we have to deal with. That is what I was told would happen with these cams.
For me, it was a decision of either long tubes or cams. The cams were cheaper and a better bang for the buck, so that is what I did.

 

Boost is not a measure of power, it is a measure of how much air is backed up in the intake tract. The name of the game is how many oxygen molecules can be passed through the engine.

Take an engine that makes 8 PSIG of boost. Now improve the flow until you only get 5 PSIG of boost. That engine should make more power because more air is actually flowing through the engine instead of backing up in the manifold. Of course, you can now add a larger pulley and get some more additional power, so long as you are not exceeding the efficient flow capacity of the blower.

I'm just thinking out loud also.

 

Well dang Loosebolt, now I don't feel quite so *inadequate*. I knew you had a 2# advantage over me that sat morning. But I did'nt know about the cams.

I don't feel so bad now, WOT

 

I think someone said that boost was just backpressure. When I asked about headers and so fourth, everyone said you will loose some boost. So right then and there I threw out the idea of headers until I read some more about it and they said you are still flowing the same amount of air, you just lost restriction which is going to give you more power. Anyways I said in another thread, porting the heads and cams is out of the question for me only due to the fact that I want to see what comes out as far as heads for these trucks.

 

Good post discussion. I blew a plug and was going to replace the head and port both sides. Maybe I will just stick with stock heads if it's not going to get me any gains.

loosebolt, tell me about your cams, where, and how much.

 

well, for what it's worth, I just called Extrude Hone to ask some questions.

I spoke to a guy named Rick.

He said that honing these heads does "OK".

He said it would probably pick up 20 horsepower.

I was thinking of buying a new lower intake and sending it off as well and having the intake and heads port matched when they do the extrude hone process.

However, at a cost of:
$900 for processing aluminum cylinder heads plus
$160 or $80 per head for port matching plus
$625 for processing an aluminum intake (which he said he didn't even think would do anything plus
$80 for port matching the intake.

$1765 sounds a little pricey to me for a whopping 20 HP!

Then again, thats just about what long tubes and exhaust costs right? for an equal gain


hmmmm....

more thinking.

Click here for more information on the "Extrude Hone - POWERFLOW" process...

later,
chris

 

Rick is a great guy to deal with.

For those of you that think extruding the upper intake is useless, you should talk to Rick and get the straight scoop rather than what your being told by someone that doesnt believe in it. I know of many believers in the extrude hone process and if you dont think it works, you might want to check out a Winston/Nextel cup engine up close.

Good Info Superfords, cant wait to see what your final combination turns out to be.

SUP CRASH

 

I have a ported upper intake which is also gasket matched to my KB adapter plate and throttle body and PSP nitrous plate. What gains will I get if this is extrude honed? I seriously doubt there would be substancial gains. If I was to call Rick what is he going to tell me. Yes, you will have a gain? How does he know? Does he test his extrude honed upper intake on my truck at the dyno and compare it to my port job?


IEHRCE

(is extrude hone really cost effective)

 

Just out of curiousity, where you running a street program or a race program that day?

I took your words of wisdom and the new mod will be here shortly

 

I tried the Crower stage 3 cams with a stock Eaton overspinning it with an 8# and 2.5 # upper......here are the big power #s....378 rwhp and 520 tq......was a big mistake.....

 

promodlightning,
here is a post that you made on a previous camshaft thread way back on September 4th (you remember, yesterday...?):

but less than 24 hours later you say:

how did it go from being "the bomb" to being "a big mistake"?

also, I don't understand those numbers at all, my 2001 truck made 404/502 with just a chip/filter/and #6lower/#2upper pulllies. hell, that truck made 382rwhp with just a jdm chip and NOTHING ELSE. that was back in june of 01. something doesn't sound right.

later,
chris

 

Rick is very helpful and he will flow test your particular upper intake before and after and give you the numbers, just give hime a call.

BTJ got his done in person and Rick was very helpful and I believe he left BTJ's upper intake on the Extrude flow machine for 4 hours.

YIRIWI (yes, it really is worth it)

BUNNIES ROCK

 

Changed to a KB blower.....