stilettoman

"I'm thinking modding the standard plenum is the way to go. Will have a good look at it this weekend and hopefully come up with something." My fabricator friend, Sean O'Brien, has come up with a concept you might want to consider - relatively simple if you have a good aluminum welder who can help you. Just make a plate that bolts to the lower manifold, and then weld on a cast aluminum V8 valve cover. Dozens of styles are available from very plain, no writing or logo to the old style with ribs cast in, some with names like Offenhauser or Edelbrock. The volume is about right, and the length will allow some over hang at the rear so the idle air valve can be hidden underneath if you want a clean look. The throttle body flange can be welded to the front, straight out or angled as required. I like this RB20 so much I bought another complete R32 front clip when I had the chance, got one with 35,000 miles. Recently I found the car I have been looking for, in nice condition for a very good price. It is an iconic design, the first modern car made in the U.S. after WWII, fairly small, weighs only 2700 pounds, and is a 1948 model. As soon as Sean saw this, he said we have to make in intake that looks like a 50's hot rod part, and then he come up with the idea of using a valve cover. I soon found one with the appropriate name cast in, and had it shipped as-cast with no holes drilled. Photo attached. In case you think this is just another engine swap, be advised the level of insanity goes well beyond that. The complete R32 front structure will be grafted to the firewall and frame rails, so the entire front suspension will be Skyline. I also acquired an R33 rear suspension,which will fit nicely under the rear frame rails. Suffice it to say this will not be your grandfather's Studebaker. Don't mean to hijack this thread - I will start a topic in the Project section as soon as we begin the cutting and welding. And those who appreciate our "automotive art" may want to look at this: www.cardomain.com/ride/646433

"the shape that that plenum has been given stands a good chance of having good distribution. But unless you either flow tested it, or better yet had 6 exhaust pyros installed, you really don't know." I agree completely. I retired from Boeing a few years ago after 36 years, B.S. and M.S. in aero engineering ( you may have heard of Boeing - they make those noisy things that occasionally fly over your house). Never worked as an aerodynamicist, but I think I understand the basics of airflow, also commonly known as black magic. But the advantage of a mod like this is you can test drive it, and if you have nothing better to do, dyno test it. I plan to install a wheel speed sensor for my friend's rally computer, and then I can get some pretty accurate horspower and torque curves. There are other types of "performance mods" that cannot be easily tested. I have several friends who are very experienced, expert aerodynamicists, and the thing we most often laugh about over a beer is this amazing fad that has been going on for more than 40 years, and shows no signs of fading away. I refer of course to this idea of taking a really nice looking car and cluttering up the shape with a wing or spoiler on the back end. Without exception, all of my aero friends agree that 1. It may or may not produce any down force, but you will never know without some very difficult and expensive testing. 2. Only a tiny fraction of the people who do this for street use will ever go fast enough for the wing to make any noticeable difference. Hope this tirade doesn't get me banned form the forum.

I am new to this forum, have never driven a Skyline, and my only experience with RB motors is with the RB20DET which I installed in my 1984 RX-7. However, we did modify the intake manifold, not for more performance but to get rid of the clutter on top of the motor. Before we even looked at the various intakes that are shown on the web, my fabricator friend cut up the stock intake and modified it as shown. He cut up an old Porsche 944 intake to get the pieces he wanted for a factory "cast" look. The main point I want to make is that if you have the skills available, you can do this without changing the runner lengths. Of course the plenum volume has been significantly reduced. Everyone who has driven this thing seems to be impressed with the torque over the speed range.

Thanks for the replies - that takes away the mystery somewhat. I have owned a lot of cars, but this is my first experience with a turbo. As I stated before, the purpose of the custom intake was purely cosmetic - to get rid of all the clutter on top of the motor. I already described this here: http://www.skylinesaustralia.com/forums/topic/428272-not-living-in-oz-but-one-of-the-other-colonies/

I have a 1992 RB20DET from a 1992 R-32, no mods that could effect boost - we made a custom intake manifold, but that was strictly for cosmetic reasons. The wastegate controller does not appear to have been tampered with. It goes right up to 11 pounds boost, but never over that. 1. What is the normal max boost pressure on this engine when completely stock? 2. What is the rated horsepower, and at what boost pressure is it measured? I have done quite a bit of searching, can't find the answer these seemingly simple questions. Anyone here know the answers?

" #6 also, more pics of your car please. and I like the coil cover honeycomb." My original post gives the URL for my Cardomain page, which has photos and details of the build process - here it is again: http://www.cardomain.com/ride/3936025/1984-mazda-rx-7/ The perforated metal I used for the coil pack cover can be expensive from normal sources - I bought a door from a server cabinet, scrap price from a computer recycler. Some of you might enjoy this video of a recent project I designed and built:

I have been an RB20 owner for about 18 months, spent a lot of time reading on the forums, and the most knowledgeable people ( who speak English) seem to be in Oz. Got a couple of issues with the RB20, and eventually would like some help sorting out. But for now, I just want to know if you are trying to keep it to Australia owners only? My RB20 powered 1984 RX-7 is, I suspect, pretty unique. Seems like a perfect fit for the car,just the right power for a 2500 pound curb weight, and I am getting really excellent fuel mileage. I hated the cluttered look of the Skyline engine compartment, so I relocated the throttle body, blowoff valve and ignition module, and recently the PCV fittings. I also came up with a solution to the problem of the coil packs having to live with all the heat below that solid cover. Thought some of your owners might like to see how I solved that problem. Photos if you scroll to the bottom of this page: http://www.cardomain.com/ride/3936025/1984-mazda-rx-7/ I recently bought another RB20 front clip and I am planning a much more ambitious project in the next few months. But I am in Seattle, and don't want to intrude if you are trying to be exclusive to Australia.