Nope I didn't do that. My whole design goal was to keep area the same but increase airflow. I'm more a fan of maxing out what you have before you make it larger. My sleeves are the same oval shape as the exhaust ports all the way to the header.

 

So should I clean up the rough casting in my GReddy TB elbow, or leave it the way it is?

 

we went canoeing last summer, and that makes a lot more sense now =)

 

why? i got 353 on th 9.5 engine on 87, and that had more overlap than this one will.

you know better than to say can't to me

 

fred, did you ever see that thread where i tried to copy your sleeves?
https://www.rx7club.com/showthread.p...hlight=sleeves

i've cleaned them up since then and they're ready to go in something...i just don't have the time to put that pj into effect.

 

Oh, I'm not saying can't to you. I'm saying can't to the fuel.

B

 

you're overlooking the alcohol

 

Then that's deceptive in what you've said because it's not truly 87 octane.

B

 

it's $.20 a gallon cheaper at the pump. i'm not going to get drawn into a semantic debate over it. and fyi-- it'll get tuned before the aux. injection, as always. extra safety doesn't hurt.

** isn't it past your bedtime? your mom would be upset if she knew you were up at this hour.

 

hey didnt u show that before on the west site, didnt u say it was jose vidal that thank god moved

 

i didn't say it was jose vidal. but he did lose his business license for ripping too many people off. tooooo toooooo ******* bad. i have no sympathy for thieves.

 

Couldn't agree more


-S-

 

fine, i'll do it without the alcohol.
my goal with that wasn't to get drawn into some bullshit debate, it was to save a few bucks on every tank of gas.

 

Nothing wrong with saving money on gas.

-S-

 

~$40/month

 

Somehow I think having them machined is much easier!

 

i concur, but you said you couldn't get them when i asked. oh well... only an hour or so each. nott too much of a time investment, by comparison.

 

okay, this started out in one direction and evolved into some great stuff. i vote for mods to archive this thread on the merits of pages 4 to 7.

 

naw... just start new threads on each topic, that way they can be expounded on individually.

 

I have a few questions here.

What material did you use?

Most header tubes are round. Don't you think a transition would be good? If so,how did you do it?

What about a sleeve transitioning from oval to round, yet keeping the same approximate cross-sectional area?


Edit: When I say "header" I mean both header and ehaust manifold for turbo.

Is this how you decided on header diameter?

 

When I did my first set of new sleeves 6 or 7 years ago, I used 304 stainless and had a flange made. As far as transition this is simple. Just take the header tube and gently narrow one end down to an oval. It is very easy to make a smooth transition. Of course doing this you can't use any existing headers or turbo exhaust manifolds (not that this is a bad thing!). You do have to custom fab your own. The header tube diameter is determined by the size of the opening in the sleeve. You can keep the area roughly the same which keeps exhaust velocity high. On my engine I had a 1 5/8" pipe with the stock sized ports. That's how much area the stock ports have. I know some people say that this will hurt power as a 1 5/8" pipe can't flow as much as a 2" but they just aren't thinking properly. While a larger pipe has the ability to flow more, when used in an application such as this, it won't. All that will happen is that you will slow down the air entering it which will hurt velocity, scavenging, etc. The fact that a 2" pipe can flow more is irrelevant since it can also outflow the stock exhaust port. There is no point in making your primary outflow your exhaust port like that. Make it it's equal or flow slightly better but that's it. Velocity is more important. When you lose velocity, you lose (waste) energy.

 

They used the golf ball dimple effect on Lance Armstrong's bikes and some parts of his clothing to help reduce drag

 

WTF ? Was the guy blind ? Even a noob would be able to port within the templates. That is just bad work.

 

I guess what I was looking for here was why not use the sleeve for the transition? Instead of ovaling the pipe. Use a dia, 1 5/8" if thats the magic dia., at the exit of the sleeve so your custum turbo mani or header is easier to make.

I understand your thinking on velocity. Sooner or later you will need to transition to a round tube.

I also agree that there has to be a drop in the velocity in the factory exaust sleeve. (talking turbo).

 

The problem is that the sleeve is only a couple of inches long. I keep the shape of the port all the way out of the engine for these couple of inches and then use the pipe transition over more than just 2 more inches. Mine transition from oval to round smoothly over about 4" or so which is double the length of the sleeves. If the shape changed inside the confines of the sleeve but the area stayed the same, the shape change would be too drastic and would cause turbulence.