That's the realization I'm coming to. At first this build was to be minimum cost. But then I got to thinking that with just a bit of additional cost I could go with the better converter and pick up mileage. Then the idea was to port the heads just a bit to get more mileage. Now, with a fair amount of work on the heads up front and a plan to have true duals behind, it just doesn't make sense to stick stock manifolds in the middle. Kinda like a strong chain with one little link in the middle.

 

Gary, your wife and mine must know each other. Gotta be careful how I sell an "upgrade" to her.

 

After 42 years I usually know what she's thinking. USUALLY. Every once in a while she surprises me. And, every once in a while I surprise her. Ordered a rather expensive add-on for her quilting machine yesterday, unbeknownst to her. Hope to get it in while she's gone visiting the 4 week old twin grandkids.

But, she deserves it for letting me continue to throw money at this pickup - especially since I'll need to sell it when I finally get Dad's. And then I'll be throwing money at it!

Anyway, I'm blessed to have her and thank the Lord daily for her.

 

You're the Man, Gary.

Thanks for the inspiration, and I'm not talking about the heads.

Kevin

 

I've started the writeup re porting the heads on my web site. Please take a look at it and let me know if you agree with the approach: Porting D8OE Heads

Obviously a lot more needs to be done. And, I'm sure there are typos and various other mistakes. Anyway, I'm looking for direction if you think I'm headed the wrong way.

Also, while I have you, I'm thinking about doing a thread on the whole engine build awa the new torque converter. Actually, maybe somewhat along the lines of how the web page starts, but provide more info on each of the things I've done or am doing and wrap it up with how it worked out.

Or, I could actually do it at the bottom of the web page. Or, maybe both there awa the forum. Would include costs, how it worked/didn't, etc.

Your thoughts, PLEASE!

 

You can't add the percent gains. It never works out. If I added all the HP claims for my diesel, it would be over 750hp, but it actually makes just under 400.

I like that you are trying to make a truck with the aerodynamics of a brick into a Prius. I really wish you luck with that.

Now that I have said that....


Performance and efficiency can go hand in hand. An engine that makes more power can run at a lower rpm and still have enough torque to maintain the same speed as a stock engine at higher rpms.

Step by step gains noted on the page would be good, but since this is a rebuild, we will have to wait for the final product.

Yes, include everything you have done, wether it works, etc.

 

I guess I'll go back and re-think how I want to state the "summary" as I didn't mean to set an expectation that the truck will get excellent mileage. Instead, what I meant to say is that I think I can meet my goal of 15 MPG since the #'s come up higher than that. But, that's not what you read so I'll rethink that. As for the Prius comment, that was cute.

But, I need some clarification on the last comment, the "yes, include everything". Are you saying I should start a new thread regarding the whole project? Or put all of that on my web page? Or both? Or?

 

State what you want to get, what you expect. Don't change it yet, I am just submitting my opinion. I am sure others will add theirs and tell me I am wrong. In the real world, without overdrive, I would set my sights a little lower on mpgs. I just see it as unrealistic unless you drive 45-50mph on the highway. Changing to the 3.25s would help but 3.0s would be better.

I noticed with my c6 and 3:55 gears that my tach says the engine is going 2600rpm at 60mph. This partially explains my 12mpg avg and my desire for an overdrive(not an AOD). I do think I could get over 20 with a 2.3/c4 in my truck....

By "include everything", I mean if you add it to the project, tell it in the blog. If it works, great, but how did it work, and vice versa. Include that you used banded valve stem seals instead of umbrella style and the reason, etc.

 

I'm back from visiting my brand-new grandtwins and am starting more work on the heads. While gone I picked up another book and read it awa read more I found on-line.

One of my goals was to read about "shrouding" as mentioned by Stang. As I understand it, this pertains to having the walls of the combustion chamber so close to the head of the valve that a portion of the valve is effectively blocked, or "shrouded". From what I can see the D8OE heads don't really have that much shrouding as the edges if the valves are reasonably-far from the valves, as shown here:


And, since unshrouding the valve requires the removal of material in the heads which lowers the compression ratio, which is low already, I'm reluctant to do so. However, I will spend some time polishing the combustion chambers to remove the as-cast roughness.

And, speaking of polishing, I've built a tool-post grinder attachment for my lathe that lets me use my Dremel tool on things chucked in the lathe. Further, I tried it today on an old valve and find that it seems to do a decent job on the back of the valve as well as the face of the valve. Here's a shot of what I did on the back to both polish awa to remove the lip just below the area that has been lapped into the seat.


Please let me know what you think, but tomorrow I start on the valves for the engine I'm building so your thoughts will be timely.

 

Gary,
Look at the image Stangcr posted of his swirl polished valves...


You see the polish is not concentric.
This is possible using a Roloc disc on a die grinder and turning the valve in the lathe at slow speed.

The charge still has to come out from under the edge of the valve at low lift.
Any lip (or shrouding) impedes flow at this critical time.

As you are polishing, CC the heads to match their volume.
Get a piece of 1/4" plexi and drill a hole towards one corner.
Seal it to the surface using grease.
With a graduated burette fill the chamber with ATF.
Read what's remaining and make a note of it for each cylinder.
If the head's volume is not where you want for a static CR when you're done, bring it into the machine shop and have them cut it.

Just sayin'..

 

Quick question while I ponder the rest: Why is the swirl better than a smooth polish?

 

Not that I remember too much from fluid dynamics... but I believe that even on a very small scale the surface irregularities affect laminar flow and vortice generation.

I do know from my rocket work that surface finish down to microns is very important, especially in the transonic range.

The first thing the incoming charge hits coming down the port is the back of the valve.
And one thing about porting is to keep flow as high as possible (without supersonic stalling) by limiting the amount you hog out of the ports, depending on displacement and max RPM's
If it weren't for the charge inertia one could never see higher than 100% VE in normally aspirated pure race engines.

Why go through the effort and leave so much on the table?

 

Um, what did all that mean in English??

 

I think he's generally wanting to say that smooth flow without any turbulence (perhaps that induced by surface irregularities) is better. Lots of engine builders will talk this way.

Oddly enough, the 2.3L 4-banger in my DD Tempo has what Ford calls a High Swirl Combustion (HSC) engine where turbulence is purposely designed into the engine apparently on the theory that a higher swirl rate would help to atomize fuel better at lower rpm's, improving both low rpm torque and helping with mpg's.

 

Too small a port for a given cylinder volume and redline will cause supersonic shock waves and choke off the flow. (not usually a problem in a street engine)

Too large a port will act sluggish and the charge will not rush into the cylinder.
It can also allow the intake charge to separate from the wall and cause eddy's, turbulence and/or reversion.

Sometimes fuel will drop out of suspension and travel back UP the runner!

Earlier in this thread there was a section showing too much removed from the short side radius.
If this happens the charge there will separate from the wall and 'overshoot' the turn, crashing into the rest of the charge just as it is trying to get past the back of the valve and into the cylinder.

Surface finish is important, but it doesn't need to be a mirrorlike polish on the intake side.
The exhaust DOES want to look that way because a mirror or even a ceramic coating will reflect heat and keep it in the exhaust and out of the engine.
Increasing velocity and reducing cooling load on the engine.