New 20b intake plenum and runners

[gmonsen]

One of the biggest problems with running a 20b NA is getting air into the intake ports. I found that with th stock upper intake, you run out of air at about 5500 or so. So, we designed a new intake plenum and runners.

Here are some pictures of the plenum canister, the ends of it, and the first runners being made. The guy doing it, Victor Yordy, got cute and made a "G" on the end of the plenum. I am having him remake it with a "7" on it exactly like the "7" I'm using in my new emblem.

Gordon
Here's the design we started with, although it has changed in the dimensions. The plenum is now 7 inches in diameter and the runners start at 2 inches and taper down to 1.5 inches...
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/Plenumandintake1001.jpg

Here's the 7 inch diameter plenum canister...
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_5941.jpg

Here's the "G" he embossed (right?) on the end of the plenum. He's going to make it with a "7" instead (like in my new emblem)...
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_5942.jpg

Here's a runner being made. The max we can go at the plenum is about 2 inches in diameter and the LIM has 1.5 inch diameter runners, so that's the most taper (increase in velocity) we could do...
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/7_100_5952.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_5947.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/3_100_5948.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_5949.jpg

[Herblenny]

Gordon,

How about something like this... As I have considered building an N/A 20B RX3 when I had it and thought about this..

http://www.efihardware.com/_linkedimages/20B-rotary-complete-kit-sizes-50mm-to-55mm_1932.jpg?cache=20100719115708

http://www.efihardware.com/_linkedimages/20B-rotary-complete-kit-sizes-50mm-to-55mm_1935.jpg?cache=20100719115802
And they make FG intake..

http://www.efihardware.com/_images/medium/805-001a_20b_rotary_kit.jpg?cache=20090817182718

http://www.efihardware.com/_images/medium/805-001b_20b_rotary_kit.jpg?cache=20090817182718

More info here: http://www.efihardware.com/products/c54/Rotary-Throttle-Body-Kits

[gmonsen]

Phil... I know the guys at EFI. Good people. I am actually working towards an ITB setup. I kind of have someone on it, but want to understand the whole intake thing a bit more. Will be using the Jenvey throttle bodies.

I'm doing a video documentary in January showing the effects of different intakes and throttle bodies on power, which I am hoping others thinking about going this way can see what the alternatives are for power versus cost and refinement.

Gordon

[Twisted7]

what is the expected completed date?

[gmonsen]

Twisted... I expect it to be on the dyno next in about 3 weeks. Its supposed to be done sooner, but could be done later, if you know what I mean. ;)

Gordon

[hades]

wow this will be awesome.

[vex]

Just out of curiosity are you guys modeling this design off of a previously developed manifold or is this completely new?

[gmonsen]

Hard to say anything is "new". We have made and seen others make plenums and intakes and we sized things and designed them based somewhat on math, but there are constraints that you have to work within. The total volume of the plenum is more than double that of the stock unit and the runners taper from 2.25" Internal Diameter to 1.5" diameter over the length of the runner. Also, we have avoided any and all 90 deg angles and have smoothed the air flow as much as possible. So, we have a lot more volume and the runners should increase the velocity of air we can get through the motor, which is the whole trick to NA motors.

Gordon

[vex]

Ahhh, I see. I was under the impression it was going to be forced induced and I was concerned about starving the end runners.

[gmonsen]

Vex... Nope. I'm one of those eccentric 20b NA lovers. :)

Quick update on the intake plenum and runners. Took more time than I thought to get the holes cut in the plenum for the runners and the flanges for the throttle body and mating to the new upper runners. I used a laser cutting shop and it took them a lot longer to schedule such a small job and cost a bit more than I had expected. The pieces look great, though I may use a water cutter next time.

Flanges for throttle body and runners
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_5987.jpg

Here's an end on view of the new plenum compared with the old one. The old plenum was 3 inches in diameter and nearly 14 inches long. The new plenum is 6 inches in diameter by 14 inches. So, the old plenum had 98 cubic inches of volume and the new one has 396 inches of volume. This should help.

New plenum with old plenum and runners:
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/3_100_5995.jpg

Comparison from another angle:
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_5996.jpg

The old runners were about 1.25" going down to 1 inch over about 8 inch or so (from memory). The new runners are only only to be about 2 inches long and go from 2 inches in diameter down to 1 inch over that length of 2 inches. Since the old runners only squeeze down a quarter inch (or not at all since its hard to measure the interior of the cast runners accurately and they could essentially be 1" all the way), the runners need to be as long as possible to get any velocity. Our "fire-hose" shorty runner squeezes down by half over just 2 inches. We have to make runners that are longer than the 2 inches, so that the ends can be gripped in the bender to curve the whole runner a bit and then we'll cut off both ends to mate correctly with the LIM and plenum flanges. My hope is that the much larger plenum, combined with the fire-hose runners will solve my fueling problem at the top end.

My guy made up this curved end piece for the plenum with my initial. The actual plenum will have a "7" on the end:
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/5_100_5945.jpg

I think I'm about a week away from having this done and back on the car, so we can hook up the bigger throttle body and give it a whang on the dyno and will post up pictures as we go.

Gordon

[TitaniumTT]

I love custom out-side-the-box stuff. What are you doing for fuel injectors, Gordon?

[RX-Heven]

What throttle body will you be using?

[gmonsen]

Thanks, Brian. Its a lot of fun. Not sure on the injectors once this is on. Its a lot more (4x) air. I was running out of air beginning at around 5500 rpm, not fuel. So, we'll have to see.

Rx-heven... Love your build. Still thinking about following in your footsteps. Almost did it some years ago. As to the TB, its a modified and extrude-honed Rotary-Works 90mm 20b throttle body. (They also make a 90mm 13b version.) I am wondering if that is sufficient for my power curve goals, but won't know till its all back together. As Logan's work shows, there's a lot of experimenting and new stuff to be done in NA. We're only just getting into it and yet there are now a bunch (10-15) of street NA 20b's making 425-475 whp.

Gordon

[diabolical1]

for krikey's sake, man ... less typing, and more working! i want to see this thing assembled and bolted to your car. i need a fix. :)

[gmonsen]

I think the new intake plenum and runners should be tac welded up by end of week and hopefully we can get it on and be sure it fits right. Then back for final changes, grinding and a polish, and back again for install and dyno. Here are a few pictures of the progress this week. The throttle body is on, the plenum roughed out, and the runners will be done tomorrow.

We have changed the design of the runners -- again -- because it made no sense to make this and still use the lower intake manifold. Mazda did a great job on the LIM in terms of fitting the turbos and emissions stuff for the Cosmo, but this manifold cannot be modified to flow well. So, we are taking the runners all the way down to just above the base of the LIM -- sort of using it as an extended flange -- and welding the runners to that as a base, so everything bolts up well to the block. We may work on the base of the LIM a bit to smooth the flow into the intake ports. Try to match them as closely as possible by porting the LIM base out. When its all done (welded, ground, and polished), I am going to have them ceramic coated an off white.

I have a real feeling that we are going to see some major horsepower jump here, because the LIM is just such a restriction. We will have increased volume by 4 times and really speeded up velocity at high rpm. This appears to be so critical at higher rpm where the combustion dish is going by so fast.

Gordon

You can see that the primary runners are quite a bit smaller (1x1.25") than the secondaries (1.6x1.6"), so the taper is greater for the primaries. It'll be interesting to see the impact on the primaries.

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_6000.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_6000.jpg

Here is the revised intake plenum:
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_6002.jpg

And the flange for the Rotary-Works 90mm throttle body being mated to the intake plenum:
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_6006.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_6004.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/3_100_6005.jpg

[warwickben]

Any updates?

[gmonsen]

Warwicken... Yep. Three failures on the runners!!! The fourth one worked and the whole thing should be done by mid next week. Its a real pain getting the 120 degree bend just right with a tapered runner without crimping it. We ended up taking 2 inch pipe and mandrel bending it to the right curve and then cutting a "slit" in it and hammering the sides of the slit together to get the exact taper. They look good. Victor is "trumpeting" them into the plenum now. So, some pictures soon of the runners and then the finished piece. Then, another week to some new numbers!

Gordon

[TitaniumTT]

Damn, sounds like a lot of fun. Can't wait to see the finished product though. Hopefully the rewards are worth the pain

Hey Gordon, just an FYI, there's a group of us heading to Dave's one the 29th. 4 of us from the forum and maybe a 20B FD as well.... just in case you've got nothing going on next saturday ;)

[gmonsen]

TitaniumTT... I'll be there if the weather isn't lousy, if you guys are on for sure. I stop by Dave's every so often and just sit there all day doing nothing while Dave talks on the phone and tells me we can talk soon... He may have the new paint booth done. You can also see a few new things on my car that I haven't shown yet.

Gordon

[warwickben]

I'm a metal worker by trade. Next time you build one try this. Turn a steel stake down to the taper you need. You can heat it up and curve it as u need. Cut two strips of sheet metal and hammer them around the metal stake trim and weld both halfs togarther.

Can't wait to see more pics.

[TitaniumTT]

Gordon, we're on for sure... unless there is a TON of snow... if that's the case we all may head up early to beat it? Either way, I'm planning on being there to test a few coils and see if two rx8's can match one RE in power :rofl: then of course probably get blown out of the water by a 20B turbo FD... should be fun.

I know those days at Daves all to well.... he's got damn good coffee though :smilielol5:

[hades]

at work we use a product from Lydall to help protect the cab from the turbo. The product is has a pressure sensitive adhesive backing, a 1/2" fiberglass core and a stainless steel outer skin.

This does a great job of protecting metal and fiberglass from the turbos--which are a bit too close.

I wish work didn't throw out my 8' rolled sample..:( or i would send you a piece of it just to see how it.

Just throwing some ideas out there. I designed aftertreatment components for Peterbilt the last few years. Fighting heat has been a challenge. I do have some pretty cool materials to try out though.

good luck.

[gmonsen]

Ben... I actually had that idea and it would have been next. We tried filling the runners with sand before bending them and there was still a small crimp in them. Bending a full 2 inch diameter aluminum pipe first and then slitting it and moving the two sides together seems to have worked.

Brian... Good deal. I guess Ray's bringing up Chris' car? Its funny. That car was here for maybe a total of 4 -5 years. Now, I've got Davin's black touring in the garage for a time while he's in California. I should start charging for storage...

The motor is ready to be assembled and we are just waiting on the intake to be completed to put it together. We have my original headers and a new set that Logan (defined autoworks) made for me that he claims will add 20-25 foot pounds of torque. So, we'll be doing a lot of dyno work in about 2 weeks?

Gordon

[TitaniumTT]

Yeah, if Ray can work a day off he'll be there. I didn't realize Ray ended up with Chris's car... that's really awesome. I've been wanting to see that beaut

If you're offering free storage... I may take you up on it so I'm not tempted to take the FC apart once I get her back together :rofl:

Have you thought about taking the al pipe to an exhaust shop? They usually have a bunch of mandrels that should be able to bend without crimping. I've gotten to the point where I'm going to be building my own tubing bender in the very near future. Too many things can be built much more attractively with some mandrel bends and I'm getting to the point where off the self bends just aren't really cutting it anymore. Plans can be bought online for a few bucks, then it's just a day of millling and welding. Dies are usually about $150 iirc.

[gmonsen]

Brian... We were welding up a tube that tapered and then bending it. Taking a 2 inch pipe and bending it first works much better. We have all the tools, just did it backwards, I think.

And, yeah, Ray got Chris' car. He stole it for the price of a motor. Car still needs cosmetics.

Hades... Very cool. If worries come up, I'll reach out for some ideas?

Gordon

[warwickben]

fill with water not sand. it makes it so much easier. only way sand will work is if you can weld like a plungers on one side and compact the sand. sand has air pockets that can mover around and deform the metal. water not so much.

[gmonsen]

So, we are finally going on the manifold. It was a pain getting the runners right. The final method was to make it in 2 halves and then weld them together. We tried every other way of doing it (thanks, Warwickben) and it didn't come out right. The first 3 of these looked perfect and measure out exactly. It was a bot more complicated than we thought. Again, its the tapering while bending that's so tough. Either one without the other works fine, but its tough to do them both together. These will be done this week and back to get put on the motor next week. I am very excited that we will see some exciting results.

Gordon

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/5_100_6161.jpg

[gmonsen]

Victor is working thorough the night to get these done. They are made up in halves and welded together. That's the only way we could get the complex curves and tapering to work just right. Please don't mind the welds. They will not be visible once ground and polished and then painted.

Gordon

Look at the curves and taper of the runners. Very complex shape.
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/5_100_6166.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_6165.jpg

Notice how different the lengths of the runners were originally. The third rotor has a much longer runner than the others.
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_6163.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/3_100_6164.jpg

[warwickben]

Cant wait for pics lol.

[diabolical1]

appears to be coming together quite nicely. i can't wait to see what it does on the car. what finish are you planning on when all is said and done? coated? polished?

[gmonsen]

Here are the latest photos. (He sends a lot of progress photos every day.) The runners are tacked in place and welded to the LIM flange base. The welds are ground, but not polished.

Diabolical1... I plan to paint these gloss Jaguar Battleship grey. The housings will stay off white and the irons and end covers are all polished. The alternator is off white and the headers will be either white or grey. The throttle body is polished.

I really feel like this is art. Its the first custom functional performance piece I've designed and it looks beautiful. Now, we just nee to see how it performs on the dyno.

Gordon

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/3_100_6200.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_6207.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/5_100_6208.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/6_100_6209.jpg

[hades]

can't wait to see it done. good work.

[gmonsen]

Hades... Thanks. It should be done tomorrow. Here are the last photos I got today. The welds to the LIM flange are done and some grinding. Its really coming together.

Gordon

Here's the runners welded and the welds ground down. Pretty much how it will look until painting. The minor touch up will hardly show.
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_6214.jpg

He attaches the runners to the LIM flange base
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/6_100_6216.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_6210.jpg

[My5ABaby]

Pretty crazy setup. I'm anxious to see how well it dynos/flows.

[gmonsen]

My5ABaby... Yep. All the pretty stuff doesn't mean much, if it doesn't do the job. I think it will. The runners are bigger at the plenum and stock at the flange, so a lot more taper and thus velocity. The effect of the greater taper is especially notable on the primaries, since they go from 2.1 inches at the plenum to 1.25 inches at the flange. The plenum is 4 times the volume of the stock 20b plenum, so it will have the volume it needs at high rpm. Does that mean it will work the way I hope? Absolutely not, of course. But, a lot of the intake and exhaust work is as much art as science and a lot comes from experimenting. One way or the other, I'll learn a lot from this.

Gordon

[diabolical1]

... a lot of the intake and exhaust work is as much art as science and a lot comes from experimenting. One way or the other, I'll learn a lot from this.

so true, so true; and believe me, you won't be the only one to learn a lot from this. that's probably the thing i like about your threads the most - a lot of substance to go with the fluff. :) yes, they contain A LOT of cool stuff to look at and pine for, but they are ALWAYS informative and thought-provoking. i'm still trying to wrap my head around the "exhaust-free-air"-thing and while i'm not quite there with the understanding, i know i'll be better off when i get there.

[gmonsen]

Diabolical1... Thanks very much. I like to develop things, design things, try things... Even ones that really fail miserably. Its a lifelong avocation. I've spent a lost of time over the past 16 years playing with these and I have had a lot of help from and gotten to know so many great guys who have helped me think ideas through.

My guy welded 5 of the 6 runners to the plenum and is calling it a day. Tomorrow he will finish the last runner and put on the 2 end pieces. I am going to try to get him to emboss the "7" from the emblems he's making for me. He did a "G" on the first ones he showed me (below as well). The ends will be close to a semi circle on each end.

Gordon

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/3_100_6226.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_6225.jpg

Here are some pictures of the first end piece for the plenum. They were too shallow, but it gives you an idea of what they might look like.
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/2_100_5922.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/6_100_5926.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/5_100_5945.jpg

[gmonsen]

Haven't gotten the final pictures of the plenum yet, but have a few that show the plenum being finished. He is still working on the end cap on the plenum, because I got silly and decided to have him emboss a big "7" on the front (end) of the plenum. I probably have a picture of the wooden "7" he's using to emboss the end cap.

Gordon

Here's the buck he's using to emboss the "7".
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/6_100_6243.jpg

And, ere are a few shots of it almost completed, but some grinding and polishing to do.
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/6_100_6256.jpg
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/5_100_6255.jpg

[gmonsen]

I had Vic emboss the "7" design I made for my new emblems onto the front end cap of the plenum. He's welded it on and will do the final grinding today. Should have some finished pictures today.

Gordon

Here's the end cap with the "7" embossed on it. Its fairly subtle and sitting behind the alternator, it won'y be seen easily, I suppose, but I'll know its there.
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/5_100_6265.jpg

And here it is welded to the end and ready for grinding...
http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/6_100_6270.jpg

[gmonsen]

Here are some pictures of the completed (minus polishing and ceramic coating) plenum and runners. The grinding marks are like camouflage and make it hard to see the finished surfaces well. Victor's photography makes it almost impossible. I may be able to have him buff it out a bit and take some photos when his hands have stopped shaking from the hammering or whatever. :)

I'd love any comments on the "7" that I had Victor emboss into the front end cap. Its the same design as the "7" emblems I designed. Any feedback would be appreciated...

Gordon

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_6274.jpg

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/6_100_6276.jpg


http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/7_100_6277.jpg

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/3_100_6273.jpg

[gmonsen]

Here are some pictures of the completed (minus polishing and ceramic coating) plenum and runners. The grinding marks are like camouflage and make it hard to see the finished surfaces well. Victor's photography makes it almost impossible. I may be able to have him buff it out a bit and take some photos when his hands have stopped shaking from the hammering or whatever. :)

I'd love any comments on the "7" that I had Victor emboss into the front end cap. Its the same design as the "7" emblems I designed. Any feedback would be appreciated...

Gordon

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/4_100_6274.jpg

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/6_100_6276.jpg


http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/7_100_6277.jpg

http://i234.photobucket.com/albums/ee255/gmonsen/Mazda%20Rx7/Projects/Intake%20Plenum%20and%20Runners/3_100_6273.jpg