4bbl Slant Intake

-
RustyRatRod said:
Then you have no imagination. lol

And gosh, if you read it on .org then it must be gospel. lol
Click to expand...
lol, yup searching on google, i doubt you can feel the difference, but i had both intakes and the clifford runners are a bit wider, on the offy the base plate wont allow it to clock sideways tried it, the bolt pattern on the intake and the base plate can only go one way
 
Slantsix64 said:
lol, yup searching on google, i doubt you can feel the difference, but i had both intakes and the clifford runners are a bit wider, on the offy the base plate wont allow it to clock sideways tried it, the bolt pattern on the intake and the base plate can only go one way
Click to expand...

Get the Offenhauser 1/2 plate that will bolt right on top of the Offenhauser adapter on the intake. SIDEWAYS. It only adds 1/2". You will see it soon.
 
RustyRatRod said:
Get the Offenhauser 1/2 plate that will bolt right on top of the Offenhauser adapter on the intake. SIDEWAYS. It only adds 1/2". You will see it soon.
Click to expand...
i thought that was for holleys only? If i got to add it on top of the base plate then i would have to get a mini air cleaner because of hood clearance
 
Me, I sorta wonder how Fanie Gerber is getting on with his project to reproduce Chrysler Sout Africa's "hexapus" 4bbl intake.

Pics of original and working CAD files:


RSA_Hexapus_4bbl_Intake.jpg


turbo1.png


turbo 3.png


turbo 2.png
 
That is one amazing manifold! Interesting how it achieves equal (ish) runner lengths.
 
looks like dodo to me, 3 and 4 would have to suck. It lot of time for something that is just not that great. You could do better taking a Offy 2, 1 Barrel intake manifold and converting to 2, 2 barrel flanges.
IMG_7165.JPG
 
Hyper_pak said:
looks like dodo to me, 3 and 4 would have to suck. It lot of time for something that is just not that great. You could do better taking a Offy 2, 1 Barrel intake manifold and converting to 2, 2 barrel flanges.View attachment 1715389193
Click to expand...

Why do you think would have a problem with #3 and #4? It's pretty darn close to being an equal length runner.
 
1 and 6 have direct paths.
2 and 5 not bad.
3 and 4 have to negotiate a U turn after the plenum.
 
Hyper_pak said:
looks like dodo to me, 3 and 4 would have to suck. It lot of time for something that is just not that great.
Click to expand...

That's interesting. Can you tell us more detail about the test results you got with it? ;-)

(…because if we're just arguing based on what we see and what we think it implies, I can make at least as good a case that this design is superior to the Offy/Clifford/Weiand/etc types…)
 
KosmicKuda said:
3 and 4 have to negotiate a U turn after the plenum.
Click to expand...
…which might be a good way of countervailing the tendency of 3 and 4 to run rich when they're at the other end of the straightest, shortest path to the carburetor in the more usual types of 4bbl intake manifolds.
 
slantsixdan said:
That's interesting. Can you tell us more detail about the test results you got with it? ;-)

(…because if we're just arguing based on what we see and what we think it implies, I can make at least as good a case that this design is superior to the Offy/Clifford/Weiand/etc types…)
Click to expand...

Why don't you tell us how good it worked or if it has ever been on an engine?
I am sure anyone who has done all this 3d modeling has since run it on a dyno and has data.
 
Hyper_pak said:
looks like dodo to me, 3 and 4 would have to suck. It lot of time for something that is just not that great. You could do better taking a Offy 2, 1 Barrel intake manifold and converting to 2, 2 barrel flanges.View attachment 1715389193
Click to expand...

Not arguing, just point this out. The intake in question is very similar to the Offy 2 one barrel. Only difference I see is the single plenum VS the double plenum. The runners are shaped virtually the same. I would like to see some data on the intake. Not that it matters. If that's a "one off" as Dan says and the only other thing is 3D programs, then getting someone to make one would be a significant cost, which cuts me out. Beside, I have the Offy and it's what I will use.
 
RustyRatRod said:
Why do you think would have a problem with #3 and #4? It's pretty darn close to being an equal length runner.
Click to expand...

Might be equal length, but the bend radius will be an issue with flow. And if you picture a reflective wave, can you see the bounces in that plenum? I just don't like it, my opinion.
 
Hyper_pak said:
Why don't you tell us how good it worked
Click to expand...

Because I'm not the one who made declarations about how well or poorly it would work, I'm just the one who posted the pics, identified it as having been produced by Chrysler South Africa, and wondered how Fanie Gerber is doing in his long-term project to reproduce it. Whoever wants to know more detail would do well to ask him.

(Chrysler South Africa did manage to consistently wring really good performance out of various configurations of the Slant-6 in their production cars down there. They might've known a thing or two about what they were doing, and they might've had the kind of R&D resources that go along with being a car company.)
 
This is true, conjecture based on the impression of an image or profile doesn't always square with reality. It can, but like others on here, many many times have We have been let down by a change or profile that looks gorgeous......only to be let down on the flow bench or at the track. Sometimes it did absolutely nothing, or even a little worse, on occasion sickeningly worse. There's a lot missing from that image, primarily the carb/plate set-up & arrangement, the discharge pattern into the plenum is a complete mystery at this point so..................
 
RustyRatRod said:
I can clock the carburetor whichever direction I want on this Offenhauser too. I also think it's arguable which is better where. Do you have some data to back it up? I've never seen any dyno figures on either manifold. I've always seen people say the Clifford was "better" but I'm not sure. Certainly, the Offenhauser has closer to equal length runners......for "whatever" that's worth.
Click to expand...

Found some - knew I'd seen it somewhere...just took a while to find it again:

From Plymouth Volare Duster / Slant Six Modifications and Performance Upgrades

Dyno Testing
You can get a slant 6 on any dyno! All you need is a manual bell housing, clutch plate, and a place that's nice enough to actually want to dyno the motor. Dynoing ranges in price, I paid about $50 an hour. (which usually includes hooking the motor up). I spent a total of about 17 hours on the dyno (3 of which the dyno operater gave me free) and we got the motor to make 240hp and 270lbs. ft. torque, but that wasn't even near max, it was just a smooth run. I got tired of the dyno because I was out of money and the motor didn't seem to get very far in the 17 hours it was on. I would suggest on something like this is to try and tune it the best you can in the car first, then bring it to a dyno and optimize it.

1. Using only the primaries of an 850 Double Pumper and a Clifford 4-barrel intake with 28 degrees BTC and part throttle: 236 hp at 5250 rpm, 258 lb-ft at 4250 rpm. The low timing was used because the first time the motor was dynod it bumped the bearings on two cylinders.

2. We tried a 750 Dbl. pumper (primaries only) and it made 20 hp less. Also we tried a Offenhauser intake with the 850 and it made 30 hp less due to the smaller runners and plenum area.

The grooves on the intake may hurt fuel distribution, so 3 and 4 cylinders get lean while 1 an 6 get rich. I was told by some slant six racers to grind out the grooves and play around with the jetting, but I was also told to use a 600 double pumper; all in all, something isn't right, the motor falls on its face when the secondaries open on all three carbs. I suspect the fuel distribution rather than overcarburetion.

3. This time we ground out the grooves in the intake and tried a 750 vac. sec. Holley. It revved up smoother, so then we tried my 600 vac. sec. and misc. jets and it spittered. Next we tried a 750 double pumper and that didn't work either. so after 4 times on the dyno this is what we got with 92 octane gas, 23 degrees BTDC, and a 2 " spacer. The result: 240 hp @ 5000 rpm and 270 lb-ft @ 4000rpm.

It didn't want any more timing for some reason and a 2" spacer made 10 hp more than a 1" spacer.
 
TF360 said:
Ok, I know this has been discussed, but I am going to put a small 4bbl and headers on my 1974 225 Duster. Which intake is better Clifford or Offenhauser. Which one fits the best? Also which Headers Hooker or Clifford. Don't want Dutra manifolds. Show me your similar combo's and what problems you ran into. Thanks
Click to expand...
i have a offy 4 barrel intake with a 390 holley carb and dual hooker headers. cost much less than the cliffoed and works great.
 
You must log in or register to reply here.
-

Back
Top