Johnny Johnny

Yes, with a long slot in between the first and second plenums (and longer runners). Here's a closer design: In this design, the vertical slats help to smooth and direct the flow of air.

Vizard = David Vizard (Vizard the Wizard :-) I've got Bell's book as well, in addition to a bunch of others (Smokey Yunick in particular. Might have developed everything on American iron, but the theory still applies). The approach I'm thinking of taking is to force the incoming air from the throttle body through a long channel that is almost the entire length of the plenum, so that all parts of the plenum (and therefore runner inlets) get the same volume of air at the same velocity. I think that is key. I like your way of thinking. I might look into how those are designed and see how it might be integrated into the overall design.

Anyone?

I'm currently looking at a new intake manifold/plenum for my '93 GTS25T, and am probably going down the route of a custom built one. The Plazmaman one is certainly better for my purposes (DD and HPDE - road circuit), as it keeps the longer runners. What's the entry to the runners look like from the inside of the plenum? I've never been able to find a picture of inside the plenum to see if they use flared entries. If someone with a unit off the car and with no TB on it could snap a shot of the internals, I'd appreciate it! I'm still concerned about 2 design issues of this plenum: 1. Air still needs to make a tight 90* bend into the runners from the plenum. This is going to affect both air speed and turbulence within the plenum. 2. Though offsetting the TB helps, air distribution will not be equal across all runners. Without doing some comprehensive CFD modelling, it looks like air will either focus on runners #3 & 4 (where TB is "aimed") or #6 (common problem for any type of log-style plenum with TB at one end). The approach I'm possibly taking with mine is to use a dual-chamber design that feeds air into the main plenum equally across the length of the chamber, and parallel to the runner inlets. If anyone is interested, I've started my design/build thread here: Custom RB25DET intake manifold/plenum BTW - I'm not a business and this is not a "commercial" response to this thread. Just doing this on my own!

Standard throttle plate is a touch under 63mm.

Could someone please let me know what the intake port length of an RB25DET head is? I need the measurements from the flange face to the back of the valve for each port. Thx.

Good Day, Willing to ship to Canada? Sorry - can't PM yet as I don't have 10 posts on the site. Pls respond here or email me at rleonardmccaffery at gmail dottt com. Thanks, Ross.

Excellent - thanks!

Good Day, On a rough visual inspection they look the same (one on car, one off), but I'd like to get a confirmation that a series 2 intake manifold can be used, without modification, on a series 1 motor. Thx.

Good Day, New user, so I can't PM you yet. Willing to ship the engine damper to Canada? Please reply to rleonardmccaffery at gmail dotttt com. Thx.