My thoughts and pictures of porting my n/a 90 intake
 

First of all, a couple people have pm/e-mailed me, asking me about places to port, and my thoughts. Well here they are. Over all the stock intake flows imop a 7.5-8 out of 10. Here's the notes i wrote down before i stated on my porting.

Throttle body, black plastic spacer & upper intake-

Small ridge before throttle plates should be removed. (Won't make much flow difference.)

Double throttle shaft should be removed, and all extra threads on butterflys should be ground down. (Not much flow difference.)

The two surfaces between the black spacer and upper intake should be port matched. (Will not make much flow difference.)

Intake plenum should be cleaned up (Remove all rought surfaces)

Where intake plenum and runners meet, should be ground down. Mildy restictive for bolth primary and secondary intake runners. (Will need extra long bit)

Port match upper manifold to gasket. (1/16" could be removed from secondary runners in upper manifold.) Little bit of restriction

Middle intake-

Port match upper intake/gasket to middle intake

Remove about 1/16" from secodarys.

Air sesor of some sort could be backed out to reduce turbulance in rear most runner. Very little restiction

1/4 bump in bottom of secondary runners. (Will increase air speed through section)

Clean up any rought edges, casting molds etc.

Good sized bumps where injectors sit in middle manifold. Probably most restiction in manifold in general.

On secondary sides, Intake gasket is 3/32" larger than secondary runners. Port match Middle to gasket/lower manifold. (Need lower manifold to verify.)

Should be good for 5-10hp imop.


These are just my rambling thoughts. I have no idea if you guys can understand them or not. But they make sense to me!:D

Let me know if you guys would like for me to post pictures of what i've done so far.

CJ

I would love to see pictures!!! before and afters if you have em!

thanks!

-Daryl

One thing you overlooked. Look at where the lower intake bolts to the middle intake(right below the secondary injectors. The Intake runner on the secondary runners narrows down about 30%. The runners are not circular until just before the flange. You can stretch the circle out to a 90 degree square corner(rounded edges of course) towards the side of the flange where the mounting stud is. If you look close and feel inside the runner, you can see exactly what imtalking about. I had a bunch of pics, but I cant seem to find them. If I find them, I will post them.

I hope somebody finds their pictures hehehe...

These are pics of the area you're talking about i think.

Here is a nearly finished ported area

Here is a nearly finished one.

I don't have any pics of any stock ones....i forgot to take some pics. This is where there is a small bump that should be removed.
Its located at the very bottom of the porting area. I plan on going deeper, but i need to get some longer bits first.

This is a just a coule pics of just the runners cleaned up a little.

This is probably the last one of the middle intake. Tomorow, i'll have some pictures of the throttle body, black spacer, and upper intake hopefully. I wish i had an extra lower intake to look at.

Let me know, if you guys want to see more tomorow, and by all means let me know what you guys think. By the way, i'm no professional....this is my first attempt at porting things.

CJ

Im doin this right now to my 86 N/A. Ill post b4 and after pics in about a week or so when Im done.

Looks pretty good to me.... probably better than my 1st attempt will be :) Was that with just a little dremel tool, an air tool, or the big makita grinding tool?


~Jesse

Its a die grinder.(Air powerd) Spins about 25k rpms:)

CJ

25K rpm...thats nothing. I use a mini die grinder that spins 58K rpm:D

Heres is what I was talking about above. I cant find my pics, so I just colored one of yours red in the part that I gook out of mine. I did this to my manifold, and the gains were very impressive.

I see what your saying. But i think i want to get a lower manifold and gasket before i start grinding on something like that. I'd hate to go to far. CJ

CJ

Just curious, but did you talk to Rob Golden about any of this? I'd be interested in knowing at what point he finds manifold porting necessary and what things he would do and where. Obviously you have one of Rob's nicely ported engines, so it's going to need more air than a stocker, but I'm skeptical of finding a lot of power in the manifold on any kind of stock or mildly ported setup. I would defer 100% to Robs judgement, but I can't recall him even mentioning this in all our discussions on porting. Are we talking big numbers, or something rather moderate considering all the work involved?

Later,

Hey Blake,

I saw someone post "Pineapple Racing 6-port sleeves" in their sig... do you know anything about that?

Brad

I have'nt talked to Rob just yet. I was planning on bugging him this Friday. And hopefully he'll also have a extra 90 intake i can borrow.

To be honest, i don't think there is much more than 5-10hp. Maybe 15 on a porteded engine. But i'm no expert....so i'm just guessing. The reason why i did it was that i had an extra intake laying around. So i just decided i could'nt loose anything:D

About the 6 port sleeves. I'm the guy with it in my sig. They are basically peices of aluminum than fit into the corner of the 6 port sleeve. They're shaped so that the air/fuel mixture is curved into the engine, vs...doing a 90* turn.

CJ

Okay, I might see you there on Friday -- I'm dropping by the shop in the afternoon to get more web site material.

Later,

I saw this somewhere, I guess it was a different thread, but oh well. Someone, I think it was Blake, but I cant remember, stuffed a teflon rod into the 6 ports and took a grinder to it to make a smooth transition into into the intake ports. I have a few questions. What size teflon rod did you use? Where could I get a teflon rod like that, and how much would it cost. How noticable were the gains?

Well, it's two different things really. CJ has modified sleeves that help turn the air better than the dead end presented by the stock sleeves. To my knowledge, the sleeves are still functional. I have also done this with epoxy in the end of the sleeves. Rob Golden (owner of Pineapple Racing) makes special ones with aluminum inserts. I've been talking with him about mass producing them, but we'll see.... Anyway, this can be done without rebuilding the engine or disabling the 6-port functionality (closing them at low revs).

What I did (upon the suggestion and under the guidance of Rob Golden, in his shop) was remove the sleeves entirely and, during the course of a full rebuild, fill the ends of the 6-port runners with Teflon and reshape the ends to accomodate better flow. Without the sleeves the ports dead-end even worse than the sleeves. This can only be done during a rebuild and it looks something like this:

http://www.u-wrench.com/RE/misc/6por...flongrind2.jpg

http://www.u-wrench.com/RE/misc/6por...flonshaped.jpg

Judging power is a bit hard to do. The engine was given a large streetport (rally port) and was built for huge amounts of nitrous (large exhaust ports), so it's not easy to compare to "normal" or even other streetported engines. I will say, it took off like a rocket from 3K and up (without N2O). Much more powerful than my normal ride (an 89 GTUs with DP/PS; 147 rwhp).

Teflon is available from any local plastic distributor. You can get it in dowels, but you'll still have to turn it down to the right size (we just used a bench sanding disc). Careful, it gets hot really quickly when sanding. You'll also have to rough up the end of the runner pretty good. Finally, you might want to pin it in place with a roll pin from the side (right through the housing). I take no responsibility, however. Do this at your own risk!

Yo,


Blake, you have a GTUs? What year and color?


KS
1989 GTUs "Need to start a registry or something..."

1989, white, 89K
http://www.u-wrench.com/RE/misc/CABimages/GTUs.jpg

Hopefully this March my Rotary engine club (And blakes.:) ) will go to the dyno again. By then i hope to have a bigger mass air flow meter, and the manifold done. Then we'll see how much hp this is all worth.

Theres more than one Rotary club in Oregon? I only know of Rotary Performance Northwest.