Battle of the Intake Manifolds, B21 vs. B21ft vs. B230

Ok, what do we think/know about this stuff?

I'm wondering if i should try to did through the old archoive and paste some of the stuff I believe me and Matt hashed out about plenums and runner lengths and etc.

Also me and Dana went through sizing a manifold for a B212ft, plenum size, runner length and size, etc on that chat.

Besically, the bottom line as I see it is that the OEm manifold that most closely resembles what a custom built intake would look like is the B21f "updraft" k-jet manifold. Somebody posted, I think VPTMotorsport, about the B23et manifold being the best, as used in GPA. BUT, it had fuel injector bosses on it stock, so it made sense for them to use that one. (I'm not even sure it would have been legal for them to modify the B21 manifold).
I have my B23(0) intake all apart out in the shed right now and I'm really unimpressed with it. There is no plenum and the runner layout is wacky.

So lets hear everyone's thoughts and see if we can sign some people up to test it.
I personally would love to test it, but I don't believe we are set up to weld aluminum at work, and I would have to since I need injector bosses.

Just guessing but how important is a plenum on a turbo car where you have positive pressure on it. I see how its important on a N/A, Does anyone have any dyno charts of both motors (B21f and B23f) to compare torque curves, I realize there is a size diff (and prob camshaft) but maybe the shape of the curves could hold some info, what other means could we use to determine their value besides swapping them on a dyno? Dan242tic

I have all three manifolds in my shed. A B230FT, a B23E(updraft) and a B21FT.

If I had a k-jet car, I'd test them all out. Not hard to change a manifold.

If someone wants to "borrow" them to test them all out. I'd be willing to send them out at your expense.... (possibly anyways)

Jordan

I agree w/ dan.

The only way for this to be done right is to be done back to back on a dyno. I agree though, the updraft style seems to me to be the one that would resemble about's what a custom intake would look like imo.

I can't say that it is better, by proof of numbers... It sure seems to be much larger in terms of volume. Also the Runners appear to be longer than that of the EFI intake. As far as the Plenum goes, I don't know??? :?: I have a B230E in my 87 740 daily driver, and it has lots of low end power. It also has a high compression ratio and a V cam.

My B23ET w/ 405 SCP head, also has a V cam in it. I also have an intake from a B230E (same as B21F/B23E) on it as well. Getting everything to line up was fun, but I did it with the engine out the car. If you are going to try this I recommend a fitting the throttle body to the intake before trying to attach it to the head. The throttle body from the B21FT will mount directly to the manifold and the 90 degree elbow faces the correct direction... Problems arise from the throttle spool interfering with the micro-switch, a little bending of the mounting plate for the switch fixed that problem. The other problem I ran into was where to mount the idle air motor thingy... I was able to use the original bracket and mount it to one of the bolts for the throttle body. The hose routing took a little work. :wink: I chose to plug the hole in the intake for the idle air motor thingy, and I just used the ones that were part of the B21FT throttle body. The cool part is now I have 2 cold start injectors, one in the throttle body and the other in the intake. I plan to later hook up the second to a pressure switch to help with fuel enrichment, once I figure out how to get fuel to it... :?

The engine is in the car now and it does run, but it needs a valve adjustment and some finishing touches before I can give any first impressions... I will keep you guys updated as things progress...

Here's some pictures of the intake loosely mounted to the engine for test fitting purposes...
http://chad242ti.hypermart.net/Pictures/Engine Front view.jpg
http://chad242ti.hypermart.net/Pictures/Engine intake side.jpg
http://chad242ti.hypermart.net/Pictures/Engine view of Intake.jpg

Hmm... I asked Mike A about this a while back and his response was that the later style manifolds had less pressure drops.

I have one of each style on the bench right now, and it seems to me that the benefit of the B230 style is that all of the runners are located equidistant from the TB (and cold start injector, if you mount one there). This configuration might provide a more even mixture to all cylinders, especially as far as the cold start injector goes. However, I do like the plenum and runner design of the B21f style manifold better, so I'm not sure which one I'll end up using.

Whichever one I use, I'll be mounting all of the K-jet hardware in the manifold, so that I have more head options.

Then again, I'm an NA guy, so this might not apply to boost apps.

-steve

That is the one possible "weak" link that I see with the older manifold- the throttle body is mounted perpendicular to the runners. Certainly not an issue in vacuum, but when forcing pressurized air past that plate at partial throttle, could lead to some strange flow into the plenum which may or may not translate into uneven flow down the runners.

I think most of us know that Volvo designers knew what they were doing most of the time. The F style manifold was designed for an NA motor, they designed a different manifold for the turbo application for many reasons. Maybe it was a manufacturing issue, maybe it was because the first years w/o intercooling required a top mounted TB, maybe it just performs better for the designed power band of the B21FT.

Regardless, I'm still going to try it one of these days, and run it at the track. I hope somebody tries it on a dyno too...

Will the B234F manifold fit on a 8V head? Just a thought for a different configuration. The ones I'm thinking of have the long runners and big plenum like the B21F manifold, but have the TB in-line with the flow.

Any difference between the B21F and the B21A (carbureted) manifolds?

I hope somebody does some tests with these similar to the camshaft comparison, if not all-out dyno graphs. Maybe somebody in Sweden has already done this?

I can test fit a B234F manifold to an 8V head, but I'll tell you now it's not close to a bolt-on. The 16V has oval intake/exhaust ports.

I have a B23ET manifold from my engine before it was rebuilt... It does seem any different than the normal B230F manifold. :?: The throttle body has a spring loaded valve in the butterfly. Probably someway of relieving pressure when the throttle plate is closed... I see no real difference between this intake and the normal B230F. Maybe we could get vpmotorsport to clarify this, or maybe even Mike Aaro...