TheSamba.com :: View topic

Wed Oct 18, 2017 2:18 pm

is it right that these very short manifolds increase the torque at low and mid RPM? thay have a "miscelation chamber"

http://www.typ4shop.de/product_info.php?info=p434_...olzen.html

Wed Oct 18, 2017 7:39 pm

For low end torque, you usually want long intake runners, and for high RPM short runners. Without getting really technical, it has to do with the intake charge pulsating back and forth between the valve and the manifold's plenum, or in this case the carb's butterflies. I have no idea what a miscelation chamber is, and since I can't read what I believe to be German, its hard to tell what these manifolds are for. Could be for a 914 injection system, or universal for carbs. They are about the perfect size for doing a Type 4 engine conversion in a Type 3.

Wed Oct 18, 2017 7:52 pm

IMO that is a good design.

The short manifolds will not boost VE at low-mid rpms, but they may run better than poorly shaped short manifolds.

Wed Oct 18, 2017 7:54 pm

I just got a set for a T4 that I'm building. They're too tall for T3. They're IDF/DRLA pattern, and have no special chambers, etc. They're designed to fit better in sedans. CSP sells them, and they come in 40,44, and 48mm openings for the 914 or for the T4 head. They're very beefy at the bases for huge porting.

Short manifolds are better suited for upper RPM power, whereas longer are usually better suited for lower range power.

These require your heads to be match-ported, because they have a 3.5mm larger cross section at the base of the manifold.

Wed Oct 18, 2017 10:12 pm

It translates to "mixing" chambers. They call them "very short suction pipes with large mixing chambers," for which they claim a significant increase in low and mid-range torque. (Thanks to Google Translate.)

Thu Oct 19, 2017 6:23 am

This was my first T-4 upright conversion and I used the manifolds from one of my 914s. They came with my 36 Dell Carbs. Alum that I ported and polished.
The only problem was they were too tall and and close to my fanhousing to adjust the carbs. The late Joe of Oregon Performance DTM guy, told me to go Redline for a set of low manifolds. Ugly cast iron. But fit nice especially for T-3 implants of T-4 engines. With a T-4 it is hard to figure low in torque difference, but I believe I had a better top end with the longer manifolds. After all these years of T-4's and all the other mods I made, I could be wrong. But in general the lower manifolds cover all the bases. Less chance of carb icing for sure with a short hunk of cast iron vs Tall Aluminum.

http://www.nextgen-usa.com/morephotos/pages/bwyardrear.html

Thu Oct 19, 2017 7:55 am

bugguy1967 wrote: I just got a set for a T4 that I'm building. They're too tall for T3. They're IDF/DRLA pattern, and have no special chambers, etc. They're designed to fit better in sedans. CSP sells them, and they come in 40,44, and 48mm openings for the 914 or for the T4 head. They're very beefy at the bases for huge porting.

Short manifolds are better suited for upper RPM power, whereas longer are usually better suited for lower range power.

These require your heads to be match-ported, because they have a 3.5mm larger cross section at the base of the manifold.

Sorry, but when you say T-3, do you mean type 3, or T-3 (vanagon-tranporter)?

Thu Oct 19, 2017 8:28 am

I meant Type 3 like Square Back and Fastback --

Thu Oct 19, 2017 8:35 am

OK, Thanks! I love them type 3's....

Thu Oct 19, 2017 2:16 pm

busbusbus wrote: is it right that these very short manifolds increase the torque at low and mid RPM? thay have a "miscelation chamber"

http://www.typ4shop.de/product_info.php?info=p434_...olzen.html
Yes, and no.
The idea behind these manifolds is not new, just not very recognised.
The "plenum" area just under the flange act as a resonator or low pressure area, resulting in less fuel stand off since the mix slows down during the valve closing period and at the same time creates a tumble when the valve opens and the engine stats sucking again. This way the engine "thinks" that it has a longer intake. That way you can actually increase lower rpm torque compared to more conventional shaped manifolsds.
This works best on engines with some displacement, at least 2 liter. I´d actually almost say the larger the better.
Type 4 engines generally like the intake to be adjusted after the 4rth intake pulse. So with that in mind the shorter manifolds actually make more sense since 4rth pulse and 12" is good for peak power between 5750 and 6400 rpm. Or 13" between 5300 & 5900 rpm.

Hope this helps.
T