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Topic Review (Newest First)
05-13-2016 12:53 AM
SCHEDULEZ
Reply to vinniekq2

I recommend you try to find the test data from 1971 in different Magazine about the Offy Dual Port. If the info I posted about the 289 Ford wasn't good enough to show the Dual Ports potential, then I recommend looking at Dyno Sheets with optimized Tunes that give a better showing of the Manifolds Potential against other Manifolds. If the Jetting isn't optimized, the results aren't as good as with an optimized result.
05-12-2016 11:40 PM
vinniekq2 you gotta be selling that intake? That dual port was the worst intake Ive ever used.
A 780 is not over carbed on a 302.
For lousey articles why not bring up the stupid story of the kit that replaced 4 of the 302 pistons with 4 wood pistons with holes for no compression but perfect balance so that you could run on 1/2 an engine for 75,000 miles then put the wood pistons in the other holes and put back the 4 unused pistons and drive another 75k,,,

roflmao

The "Z28" optioned Camaro had a potent 5 liter road race engine from the factory. It made over 400 hp from the factory with a special tune,,,

the best "cam Tamer" is a smaller cam
05-12-2016 11:20 PM
SCHEDULEZ
Reference March 71 Hot Rod Magazine

If you can find the March 71 Hot Rod Magazine, there are Articles about both the Tarantula and Offy Dual Port Manifolds. The Tarantula sacrificed Low End Power for Top End Power. The Offy Dual Port was Tested on a 289 Ford with Crower 320* .544 Lift Cam with a 625 CFM Carter Carb and .004 smaller Jets, first with the Stock 4 BBL Manifold, then with the Offy Dual Port. The Test was ran from 1500 to 7500 RPMs. At 1500 RPM the stock Manifold couldn't work due to too low of an RPM for the Cam. At 1500 RPM the Offy Dual Port was pulling 84.7 HP and at 2000 RPM was pulling 12.4 more HP than the Stock Manifold. The Peak RPM for HP with the Stock Manifold was 6000 RPM and 251.3 HP. The Peak RPM with the Offy Dual Port was 7000 RPM and 278.0 HP. At the Peak Test RPM of 7500 the Stock Manifold could only put out 174.3 HP while the Offy Dual Port was putting out 270.0 HP.
I believe that this Article shows that the Offy Dual Port Manifold is more than up to doing what I have experienced and wrote about in other Posts.
05-12-2016 10:21 PM
SCHEDULEZ
Reply to JeffB

From my experience the Dual Port worked better as a Cam Tamer (liked Big Cams such as a Street Strip type vs Stock Cam) and was forgiving on Big Carbs. Most other Manifolds were very sensitive to Carb Size, the Dual Port could handle being over Carbed. My 302 Z/28 would normally be over Carbed with the Stock 780 CFM Holley, I was able to run an 850 CFM Holley with no ill effects, allowed my Full Race 302 to pull to over 8000 RPM.

I never tried the Street Master or the SP2P Manifolds but I do know with them you needed Smaller Carbs and your power dropped off by 6000 RPM and couldn't work with a Street Strip type Cam, they couldn't flow enough Air to the Cylinders. They were strictly MPG Manifolds.
05-11-2016 10:03 AM
JeffB The Streetmaster intake can actually produce better mileage if that is your goal but it takes some tuning tricks.It also works differently on different makes it will make more horse power and torque than any other manifold for the F.E. Fords and up into higher RPM's. The Weiand Accelerator is still used by some SBF hard cores like the group at sbftech.com
05-11-2016 02:32 AM
SCHEDULEZ
Quote:
Originally Posted by vinniekq2 View Post
SCHEDULEZ
I do not believe that story
I can tell you that I did the things I listed back in 1971 and 1974. In 71 I did the Installation of the Offy Dual Port. In 74 I had to rebuild the 302 Engine and built it as full race. The MPGs I listed were not a one time Fluck, they were consistent at speeds above 60 MPH (Engine RPM at 3,000 to 4,000) to 80 MPH. Most of the Modifications I have done were for better Fuel Economy as well as better Performance. My 78 Camaro (.040 over 350) has Trickflow Twisted Wedge Heads and a Comp Cams Hydraulic Roller Cam with Ultra Roller Rockers. I have to pass the California SMOG Test every 2 years, (CO .03, HC 32 PPM, NOX 176 PPM) with the Stock Q Jet and required Stock Emissions Devices. Those Numbers are better than a lot of Fuel Injected Cars. Oh by the way, my Engine puts out about 400+ Horse Power! I haven't put an Offy Dual Port back on yet due to the SMOG Requirements. I plan on doing the Manifold swap very soon as I will not be Required to SMOG my car again in the Future due to California Law exempting Pre 81 Vehicles.
05-10-2016 06:47 AM
vinniekq2 SCHEDULEZ
I do not believe that story
05-10-2016 03:49 AM
SCHEDULEZ
Offy 360 Dual Port

I have used an Offy Dual Port on 2 different Camaros, a 69 Z/28 (302, 780 HOLLEY, 3.73 Posi) and a 78 Type LT (350/Turbo 350, 3.08 Posi).
My Z/28, when stock got 17 MPG on Highway, had a lopy Idle, and almost no Low End Torque. I first tried a Tarantula, saw even less Low End Torque and slightly more Top End Power, the MPG was about the same. I then put on the Offy Dual Port, as another responder noted, I had to get the Carb Tuned for the Manifold. Once I got the correct Combination, the Engine had a very smooth Idle (like a Stock 327) and my MPG went up to 22 MPG at speeds from 60 to 80 MPH. The Engine had a lot more Low End Torque (Torque Curve moved down by almost 1,000 RPM and Power Moved up by almost 1,000 RPM). Throttle response was much quicker also. I eventually had to rebuild the Engine due to #6 Cylinder Wrist Pin gouged the Cylinder wall bad enough I had to sleeve that Cylinder. When I put the Engine together I went Full Race (12.5 Compression and a 71 Z Option Cam), even with the Offy Dual Port, my Idle Speed was 1400 RPM, but the Engine would pull all the way to over 8,000 RPM and still got 15 MPG on the Highway.
After putting the Offy Dual Port on my 78 Type LT, my MPG went from 15 to 21 MPG.
09-19-2012 11:19 AM
ryan v i'll probly make a plenum divider. My compression should be between 9 to 1 and 9.5 to 1. i'm runnin 186 double hump heads and the cam was advanced. The truck its in has 4.10 gears but a stock converter.
09-17-2012 11:28 AM
ryan v I ended up not buying the offy intake.
Another question i have is would it be a good idea to try a divider plate for the weiand or just leave it open?
09-15-2012 03:16 PM
Mr. P-Body What is written about the Offy Dual Port is 100% correct. What ISN'T written, is the divider takes up so much "room" it changes the shape of the overall runners, severly restricting it at all ranges. I saw 100 small blocks and Pontiacs with that "thing" on them in the '70s. C4-B (C-327-B) and P4-B would out-perform it at all levels, including low-end.

Edelbrock "Streetmaster", though useless above 4,500, was one open-plenum intake that could make low-end torque. The runners are so small, velocity is crazy-high. Tough to tune and not real fuel-efficient.

We use Super Victor ONLY on engines 400 CID-up. Victor (any of them) is a RACE intake, not really well-suited to street use. The power bands are very specific and usually quite narrow. Plenty of folks run them on hot street engines, and they DO "work". Victor, jr. on a 406 is a pretty nice "driver" if you don't rev it too hard. But this discussion started over a torque build... (:-

Jim
09-15-2012 09:52 AM
ap72
Quote:
Originally Posted by vinniekq2 View Post
AP,the super vic flows more air,true.The vic jr will feed a 440 to 7,000 rpm.The super vic will feed the same engine to 8500 rpm.
So why not put a 4781 holley on that 283 to match the vic jr?
If I built a 283,I would use the torker intake and a 750,where other people would likely use the performer.Its all about where you want the power and how much you are going to make.That 283 wont move enough air to make 650 horse power where a vic jr will flow enough air to make 650 hp.I had an offy dual port on my 65 acadian with a 283 and a carter carb,,,,It was not very impressive,,,
I wasn't referring to the flow, just the runner and plenum shape and size.
09-15-2012 09:40 AM
vinniekq2 AP,the super vic flows more air,true.The vic jr will feed a 440 to 7,000 rpm.The super vic will feed the same engine to 8500 rpm.
So why not put a 4781 holley on that 283 to match the vic jr?
If I built a 283,I would use the torker intake and a 750,where other people would likely use the performer.Its all about where you want the power and how much you are going to make.That 283 wont move enough air to make 650 horse power where a vic jr will flow enough air to make 650 hp.I had an offy dual port on my 65 acadian with a 283 and a carter carb,,,,It was not very impressive,,,
09-15-2012 09:21 AM
ap72
Quote:
Originally Posted by vinniekq2 View Post
Super vic is the biggest manifold or close to it that you can use before a custom intake or sheet metal intake.I wouldnt recommend it to many people.The vic Jr is better for hot street engines.

the tanantula and torker are both good manifolds if used on the correct engine.I would use either before using a performer.I would recommend that other people use the performer though.The edelbrock scorpion was a great manifold before the improved vic jr.If you are on a budget then sometimes a used intake is a good deal.If you want the "best" for your application then you have to buy exactly what fits the situation.
We all seem to agree that the offy is not the answer.
JMO but there isn't a chance in hell of me using a Vic Jr. when I can use a Super Vic in its place. UNLESS you're dealing with really small cubes like a 283 or smaller.

to 6,000- RPM, past 6,000 super Vic.
09-15-2012 09:10 AM
vinniekq2 Super vic is the biggest manifold or close to it that you can use before a custom intake or sheet metal intake.I wouldnt recommend it to many people.The vic Jr is better for hot street engines.

the tanantula and torker are both good manifolds if used on the correct engine.I would use either before using a performer.I would recommend that other people use the performer though.The edelbrock scorpion was a great manifold before the improved vic jr.If you are on a budget then sometimes a used intake is a good deal.If you want the "best" for your application then you have to buy exactly what fits the situation.
We all seem to agree that the offy is not the answer.
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