The high priced when new POS has long been and still is found on some very fast cars, the fast POS's always have a bunch of tinkering in the plenum particularly at the carb flange underside "JMHO" so as to avoid the hard ninty-degree step as AF heads to the runners and because of their rather unique port sizing that's not Med-Riser or Low Riser they are worked to port match the heads and vice-versa. Owner "tinkering and tricks" are the norm esp filling altering the plenum floor. Interestingly the design of the POS intakes regardless of engine familly or even brand with the squiggled #2 #3 #6 and #7 runners are unique and by definition promote/aid achieving equal runner lengths. JMHO- This squiggle might aid A:F by shaking up the fuel droplets instead of letting them flow uniformly down the runner.
More then a few guys have stated here on this forum that overall performance not necessarily peak power on the track puts the POS ahead of a similarly worked VictorFE on their cars.
JMHO but it's a shame the big name popular turn-key FE Race Engine builders by their very nature tend to go with the newe$t manifold (such as Victor FE) on the market that they may even have CNC programs for, not something more often found in swap-meets, junk yards and eBay. I'd love to see some of the work done on the super fast POS's when they were the only Top Dog in town by those known builders.
Re: POS's are favorites of grass-roots Racers that enjoy tinkering,
October 13 2008, 10:58 AM
Hey BB, did you get your POS worked on by Joe Craine? What port dimensions did your POS originally come with? I was wondering if these intakes came in both LR and MR versions.
I also think that with some minor work it would be a bit better than my worked RPM, but I wouldnt not compare it to a Victor.
The P-sonic is a relatively low rise intake (and Paulies on FM is actually for a low riser, other wise I'd grab it).
I ran one with filled floors on mine for years, until the epoxy went through the motor (didnt hurt anything but sure looked bad in there)
Mine ran very good on the street with tall narrow, almost LS Chevy style ports, however I really dont think the volume is there for high rpm.
I think that it needs some help on the roof of the plenum, I never did it, but its a pretty sharp edge. I'd say blend the roof, open the cloverleaf and run a 1 inch open spacer, it'd do pretty well.
I think Tommy-T had a med riser version, but I never saw one, if I find one, I'll buy it I think its a good street single plane, but not anywhere near the capability of the more modern tall single planes.
Ultimately its heroism came from Steve Christs book, saying it was the best intake for a hot FE
Like I said though, if I can find one with med riser ports, I'd play with it on the street in a heartbeat
ON EDIT: Just FYI, I have been trying off and on to buy a new one since 1997 or so. I havent seen a run cast, despite it being offered on Summit. Its always a moving month away.
Hi Ross. I'm getting that one from Paul to mess around with. The port height seems to be just a bit taller than a MR but shorter than a LR at 2.1 inches. I wonder if Offy just made one size port as a compromise. LOL
I think Blair Patrick said his SS car ran quicker with the POS versus a Victor so it seems to have potential but I wonder how much work it takes to get it to that point?
It would be kinda fun to run my street car with the Victor then try the POS at the track for comparison. Just have to figure out the best way to modify the POS. KC ports tend to be pretty wide and the POS ports are only about an inch wide.
...I ran the POS box stock on my 454 incher. The port height matched pretty good with my ported Edelbrock heads. I can't really say it ran any different than my Scott Vincent ported RPM, but I kept with the single plane "just-n-case" I NEEDED to "squeeeze!
Jay didnt have the greatest results, but I actually liked that manifold a little better than the RPM, it seemed to be very street friendly and pulled as high as I wanted to.
The setup I had it on was a stock stroke .040+ 427, with a 850 double pumper, 300 adv/250@.050, 108 LSA, on 105 ICL, Isky solid, stock iron heads, headers, and a 4 speed with 3.70's
Even during a run to SoCal with 3.00's in the rear it did just fine from idle to crazy
I ran a Port O Sonic on my Fairmont years ago, when I was still running a C6 automatic. It didn`t have any serious work down to it, just a quick gasket match.Didn`t run any better (or worse) than the F427 or ported Streetmaster,but not quite as good as my Sidewinder.Frankly, all the intakes I tried ran about the same on my mildish 428. With the 4 speed, the modified Sidewinder is still the fastest, but the only other intake I have tried with the stick has been my "out of the box" Victor. I hope to do some port matching on the Victor this winter, to see if it will be better than the Sidewinder next season.
428 powered Fairmont drag car, Best ET:10.03@132.11MPH, best 60 ft: 1.29
59 Meteor 2 dr. sedan 332, Ford O Matic
74 F350 ramp truck 390 4speed
Talking with a friend that owns a SpeedShop I've gotten the Offy
October 13 2008, 8:39 PM
low down. They hold orders back until they get enough for a production run, then the item (manifolds) might trickle in a few at a time. Even dealers have not had a new catalog or even price sheet in over a decade. This does not mean prices have not changed they are given to dealers on a need to know basis.
I find it fascinating that Offy long known as the premere source of exotic Indy engines could just maintain and rest on it's laurels. Whomever did the POS's must have had a great grasp on engineering.
Everything I've ever seen including original catalogs shows no variations in runners/port size though they reference Spread Bore and Holley bolt patterns Ive never seen anything or even evidence other then a Holley.
I run one on my 428. It's been fully ported and the roof, floors, and runners have been modified. I can't compare it with other manifolds but I ran 10.40's with it on a mild 428CJ with match ported iron CJ heads and stock short block. I'll be using the same intake on my new motor with the same heads but have increased the size of the intake valves to 2.15 and the bowls re-blended. My new shortblock is highly modified with crossbolt mains, roller cam, roller timing set, steel crank, h-beam rods and 13 to 1 light weight pop-up pistons. I haven't run it yet.
67 428 Mustang Fastback Super Pro Drag Car
92 F150 P/U Trk
2002 BMW 3.0i Z3 Roadster
90 Acura Integra
I posted some pics a while back although they weren't very good. I don't know if they can be enhanced. I sent them to Quickbbstang. Yhe intake is on my engine now so I can't take new pictures. Maybe you can do a search and find them. George
67 428 Mustang Fastback Super Pro Drag Car
92 F150 P/U Trk
2002 BMW 3.0i Z3 Roadster
90 Acura Integra
Looking around at state of the art single planes and keeping in mind Wilson
October 13 2008, 8:47 PM
carb spacers the trend is to have a smooth transition from the carb stream into the runners. In the POS's case the 1" plus 90 degree step screams for a touch up
A really well ported POS will flow roughly 360-370 CFM. A well ported Victor will flow 450-460 cfm with the same port sizes, and with much higher velocity. FWIW. Joe-JDC.
I kinda remember, I think it was Blair Patrick, saying that the POS didn't flow as well as the Victor but his car ran quicker with the POS.
Wonder what accounts for that?
The overall area is probably close, but the Victor has a built in roof for each runner that extends into the opening which keeps the runner heights very similiar, port to port. The POS has differing heights on the entry to each port, and that in effect changes the runner lengths. Airflow likes parallel ports, with slight taper for speed to increase. Anytime you increase the port height, you move the roof away from the floor, which lengthens the port in theory, but it shortens the parallelism, and shortens the ram effect as well as velocity. Will work better with more cubic inches, or shorter rod ratios. The most powerful engines today like ports that accelerate the air all the way to the valve, and that means as straight a path as possible the last couple of inches. I know swirl is important, but cylinder fill, or superfilling nets more power on a drag style engine. Joe-JDC.
but I never head of a Victor being good on the bottom, and the P-Sonic isnt bad down low. If POS runners are shorter, more volume and the plenums are similar, why would the P-sonic work down low?
Or does it NOT work better down low? If the Victor is better I may try one on mine, because I considered to P-sonic very streetable, and although I am fond of the Edelbrock RPM in theory, I think my street motor would like a fast, small runner single plane better.
If you were to take a new Victor, scribe the MR gasket, and just blend the last 3/4 to 1 inch at the port, you would have a very good street manifold. That would give you 390-400 cfm, of fast air. If you wanted a very strong manifold, go in the port 3 inches, and just bring the walls out parallel, and keep the height equal all the way through the pushrod area, and then blend to gasket size the last 1/2 inch. If done properly, this will give a MR size port that will flow roughly 440 cfm. Blending of the plenum straight down from an open carb spacer, and rounding any rough slag in the plenum area will give you the 450 cfm. If you have a stage II head that flows 320 cfm, this will be just about perfect for street and strip for your 489CI. Joe-JDC.
Joe,
I am about where a Stage 2 head would be for head flow, cam is not a drag racing cam, 242/246@.050, .595 110 LSA on 105
What we did on my RPM was a port match, and went about 2 inches into the port.
Then we did some mild plenum work, I dont have a finished picture, but here is the first step. We cut the plenum divider down slightly (1/2 inch) but left vertical wings and a blunt edge on the divider in it at Edelbrock's back shop recommendation.
I also matched the 1 inch phenolic spacer to it, and what wasnt finished in this picture is we rolled the edge of roof a bit, especially the rood of the top plane with a cartridge roll to make a more gradual turn. Basically, in the pic below,where you see alum under the spacer there we dressed it and rolled it back to a nice rounded edge, not much taken off
With and without the spacer doesnt change any part throttle drivability but with the matched spacer it gains a ton of butt-dyno up top.
I also have a matching spacer with a sheetmetal plenum divider I made to block everything I cut out so I could compare afterwards, again, no noticeable change down low either way, but you can feel it loses on top with the full divider to the carb
The question is, do you think an as cast Victor with a clean up would be worse in the 1800-2500 rpm range?
Seems like a silly range in this crowd, but with 3.70's and a .64 OD, I am in 5th gear I have a 2.36 final drive, I plan to go 4.11s soon, but it will still only be a 2.63 in 5th, so it spends some time idling around (and I dont want to downshift LOL)
Here is a pic of the intake about 1/2 way through, what is your opinion on how the Victor would behave in town, not WOT
Ross, I would leave the RPM on, and grin. I'll take a dual plane for street driving over a Victor any day. The only possible exception is the 302Victor JR., which seems to defy logic and produce torque almost like a dual plane. The RPM, with your work and gasket match, should be better below 3500 rpms. Joe-JDC.
I have heavily modified versions of both manifolds. The Victor looks cool. The Portotoilet looks like an antique. Forget looks. The Victor flows more........on or off a head. Forget about flowing manifolds just for the sake of flow numbers. I've been 9.40 with a Porto, and 9.37 with a Victor........but the Victor was in 1000 ft better air. I've been 1.21 60' with the Victor, but again 1.22 with the Porto in worse air. My opinion is that with the correct stack of various spacers, the Offy is at least as good as the Victor........maybe better. With all due respect to smart guys that flow intakes, we have to run a manifold on the racetrack to know which one is best for our combos.
If flowing manifolds, one should probably come up with an accurate way to measure runner length and volume, and plenum volume, along with flow. Then look for the trends that surface that seem to work the best. The dyno will not tell the story either......only the time slip.
The best way to know is run all of the options and Ebay the ones you don't like. Volume, cross section, runner length, entry angles, and rise to the carb are all issues that in some form or another will mingle to be what a given combo ends up liking the best.
For my junk, for one reason or another, the Victor and the Portosonic give almost identical end results, but for different reasons. I even have to drive them different. I prefer one in bad air or altitude, and the other in a mineshaft condition. I shift them at different places. Lots of things to consider. When testing, I would say you should run a manifold enough to try different spacer combos and driving styles before passing judgement.
My testing applies to 8000 rpm 440 cube Super Stock 428's. My speculation is that at some point with higher compression and larger displacements, the Victor would shine. Likewise, for smaller, lower operating or flat tappet stuff, the Portosonic OR a Street Dominator Holley is the way to go. I think I am just at the point where they can both be made to work. All of my testing is also with a 735 vacuum secondary carb, which may enter into the equation. Also, heavier cars will like the Offy or Holley and lighter cars will respond to a Victor or Dove manifold.
Just a few observations and opinions that are not guaranteed!!!!!!!!!!!!
I have to agree with Blair to an extent on this. I have almost given up on trying to "science out" which one is better on a given combination - even just on the dyno, much less a car. One of my best running ones on the car was a Street Dominator that had a 4500 flange cut into it with a bit of weld and some epoxy, along with some spacers - a plastic four hole under the carb on top of an open one (the open one had a few spray bars in it - but that's another story).
On the dyno, with fewer variables, I have seen the better intake on every measureable feature get beat by one that pretty much looks like crap. I've also seen two intakes that looked so radically different that one simply "had" to deliver different results than the other - and you could overlay the graphs and not tell which was which. Put it on a car and you have a bunch more things going on that cloud the decision even further.
Just pick one that "feels right" and flog on it. Odds are you won't be disappointed. It's not a super hard part to change out if you have the money and patience to try things. Just be prepared to be surprised.
This discussion puts Jay's intake comparo results in context
October 14 2008, 6:15 AM
When I first started reading this board, there were several folks on here that swore the Edelbrock F427 was a better intake than the newer designed Edelbrock RPM. Jay's comparo suggested that the RPM is much better without porting and slightly better with porting. End of story, Right?
Barry's and Blair's points from above make it clear that different intakes behave differently on different engines, in different cars, under different conditions. The RPM might be better than the F427 under some or even most conditions; however, there are still guys out there that switched back to the F427 after buying a new RPM. For their cars, engine combos, and conditions, the F427 felt better than the RPM, regardless of what the intake comparo results show. Something to keep in mind when shopping for an intake or considering make a switch.
I'm not sure but tend to feel that Part Throttle and below the typical
October 14 2008, 8:13 AM
2,500 or 3,000 RPM Dyno Start Figures are whole 'nother areas to mix up the situation.
The typical street/strip/track car will very rarely see WOT and I'd think it safe to say the intake that screams on a drag strip with one specific engine combo might be a dog when rolling into throttle out of a turn or simply leaving a stop light with traffic with that same specific engine combo.
I'd expect that given a cruise of 2,500-3,000 RPM on a highway for miles and miles the swapping of intakes could make for a totally different feel, smoothness, mileage, noise and etc for the entire car
There is just areas (Vac, RPM, Load, Exhaust Config etc) that any given intake might just shine in.
I know I stated it before but I had a large industrial piston type air compressor actually shatter a bunch of Stainless Steel welds and sheetmetal due to pulses from the RPM, Bore&Stroke Size and length hitting a Critical Zone. There's a bunch of Voodo that happens
I had already bought the Performer RPM and hadn't tried it yet. Vic Edelbrock was at a local trade show so I asked him what I should expect and as it turns out he was right. Guess he picks up a bit of knowledge about manifolds being in the business so long, eh. The noticeably better low end really shows up on a loaded truck and the better top end is felt too.
Bair Patrick: Please would you post some pics of your Offy POS guts?
October 14 2008, 10:37 AM
Just interests me to see the different creative tricks folks use to the old dinosaur POS's to keep FEs running fast..
I think one area that the POS is unique to other intake manifolds is the POS height of the plenum-- it seems excessively deep. It seems to me a double fill (a left side fill @ about 1" deep in center and 0" at ends of runners then ditto for the right side fill) of epoxy so that the high point would be the center of the plenum and have the raised center divide the left and right banks. This would produce a synthetic raised plenum aiming down toward the ports.
I ain't no genius, but I better keep the guts of my race stuff to myself and the other guys that buy it. We still use the Offy in competition. If I ever quit, I'll post it! When I check out, my wife will sell it all so somebody will benefit..............
that is funny BB, trying to get a class racer to post pictures of his sectrets on the world wide web.
Thank you Blair for posting your experiences and knowledge in this thread and on this forum, I appreciatte it. One question I have is on the DOVE spider if you ever got this intake to perform comparable to the Victor or Port-O-sonic on your 428 SS engines, and/or if they required a quart of splash zone....
To be honest I have never tried a Port-O-sonic myself.... I always thought they "looked" like a POS...
I have run the Street dominator before and now run the Victor.
68 Cougar XR7 street and strip car, 428 4-speed, 3560# of fun, new best 10.43@131.2 1.47 60 ft
I have used the Dove a few years back. Really big inch and/or stick shifts will work okay with the Dove. Some still run the Dove on stick shift SS engines with 428's. My opinion is that light cars do great with a Dove, but at 3500 lbs, you would have to fill the floor and the runners some up at the plenum area. A 500 inch stick shift would be in love with a Dove! OPINIONS NOT TRIED ARE NOT GUARANTEED!!!!!!!!LOL
I was trying to let Ross know that it would be easy for him to change to Victor, and make it work well without much trouble. In my experiences of porting the last 36 years, I have found that I can take a piece of junk that no one wants, and spend a few hours reworking it, and make it into a decent intake manifold that will give as much power as a "name" intake that hasn't been reworked. An engine is just an airpump that wants just enough air to perform at whatever level it is capable of performing at(cubic inches), and any more air available will not make more horsepower, no matter what the name of the intake, camshaft, block, head, etc., unless you can get it to overfill the cylinder. To that end, velocity, not having to make many turns,(including under the carb)and proper supply volumn will net the best horsepower, regardless if it is a "performer" or a sheetmetal manifold. I have built stock block 302 cubic inch SBF's that use stock E-7 heads that I port with 1.9/1.54 valves that flow only 220cfm, a .500 lift cam with 224/224, and make 400HP. The intake manifold will only flow 290cfm. I also build/port SBF heads that flow 380/280 cfm, the intake flows 410 cfm, and make enough HP to propel a fox mustang to 9.42 @145 NA. I probably port 30 sets of SBF heads to every 1 set of FE, but the theory still holds the same whether its a 732CI BBC or a 289 SBF.
I have extensively reworked the Port O Sonic, also, with welding, epoxy, spacers, turtles, and the Victor simply is easier to get more airflow, and the velocity is higher at 28 Hg on the flowbench. No one used to care about flow through the intake manifold, but when I started balancing the runners airflow, and matching the airflow to the head airflow +120%, then my engines started to consistently win. In the EFI world, I have always ported the intakes and plenums to flow so that they do not pull the heads down, when attached together, and that is a winning combination. Joe-JDC.
So Joe C the +120% flow of the runner to the head is the mark you aim for...
October 14 2008, 9:07 AM
This is kind of difficult for me to describe: I get lost trying to figure how that 120% figure you use stays in context to the complete manifolds flow. In other words the total Dynamic flow of all runners is not just the sum of each individually runner combined with the other seven.
To me Test Flowing individul runners fails to account for the dynamic conditions in a running engine where there is competition of one runner to another, the gross effect of the four runners (dual plane) or eight runners (single plane) on each other all feeding from the same plenum and their relative effects/sequences upon each other in not only gross air flow but I'd presume just as importantly the A:F quality in each runner. This all I can see would be even further effected by firing order, header tube to collector sequencing and even as small as location of the throttle(s) feeding from just the primary or primary&secondary barrels as to distribution.
You stated Victors 450-460cfm, POS 360-370cfm and RPMs 375cfm but that was obviously for each single runner in static conditions. Can it be extrapolated in some way that Victor's total flow is 3,600+cfm, POS 2,800cfm, and a RPMs 3,000+cfm in dynamic conditions? It seems to me that the manifolds total flow and more specifically plenum situation can not be determined when flowing individual runners all independently of each other........
"360-370 CFM. A well ported Victor will flow 450-460 cfm with the same port sizes, and with much higher velocity. the RPM to flow 375 CFM without having to install tubes.. Joe-JDC."
This message has been edited by qikbbstang on Oct 14, 2008 10:45 AM
The total flow would only be limited by the device mounted on the carb pad, and speed of cylinder filling in all cylinders. If you had a flow device that could measure all eight ports simultaneously, then you would have your answer. A dyno can only measure the used airflow, not potential. Joe-JDC.
I plan to either amp up the original 428 in my '66 Bird, or stick in one of my 427's, either would probably get small-chamber E-bocks. Considering the hood clearance of the 'Bird, weight of the car, cuising RPM, etc., I ve been seriously considering that cherry POS on the shelf upstairs. Someone started to port match it, got as far as scribing lines. Seems like it would probably run pretty good in that app, but wondering if it'll fit- I'll have to dig it out and compare heights to the ever-popular stock flat CI manifold. I hava a couple Street Dominators, a couple Streetmasters, Sidewinder, etc., most would seem to be too tall, and I'm not about to put a genny Sidewinder on a 'Bird- even if it would fit between the tower braces. Whaddaya think?
I think its a good street single plane, but not anywhere near the capability of the more modern tall single planes.
