F-427 and RPM

[hotrodfeguy]

Why is it on the "old forum" some people can't get it through those thick skulls that the RPM works better? I made a post over there trying to help out ERIC who had made a nice exhaust improvement and loves it. I told him he could prolly get more by swapping intakes from the F-427 to the new RPM per the FE comparo book and guys still said no we need to gonk this. I was like what? Jay has proven this by DYNO, anyways sorry for the rant and I think I am about done over there. It's just gotten so off topic and when it is on FE it's retarded. Ok hotrod is off the soapbox. 

[Drew Pojedinec]

I like Jay's book... but it seems many of the local drag racers preferred the F427 in their smaller, stockish 390's for some reason.  Dyno'd or not, I think there must be something to it.
Perhaps superstition or ignorance on their part?  I dunno.

[My427stang]

Its a very mild 390 over there, although I do think the RPM will make more peak power.  My hunch is it wouldn't make the big numbers on that specific motor. 

I also think with a COM, relatively tall gears, marginal heads, and the small displacement, down low it wouldn't gain much at all and could even be a little softer in some areas.

With that being said, when he built it, we tried to push him to an RPM, but now that it's together, I don't think it would gain enough to make the swap worthwhile.

The RPM is a hell of a manifold, but on a 300 hp motor in a truck, it wont be magic.

[jayb]

If its only a 300 HP motor, my book really didn't cover testing down to that level, so I wouldn't want to make a blanket statement that the RPM intake would be better for that application.  I think it would be, and of course when the bug bites and the owner decides to upgrade the engine to 400 HP the F427 will be holding him back.  But at 300 HP there probably isn't a big difference.

[My427stang]

Its a 9.5:1 390, 270S, shortie headers, 600 Holley, C8AE-H heads with a pocket port.   Good running truck motor

Might be a little more but I doubt a lot, he posted some significantly sub 300 chassis numbers a while back

[fe66comet]

A stock motor is just that. We all know if you improve one part another has to be upgraded to support it.

[hotrodfeguy]

I agree and now that he uncorked the exhaust. I thought that was a good time to improve the intake.

[jayb]

Its a 9.5:1 390, 270S, shortie headers, 600 Holley, C8AE-H heads with a pocket port.   Good running truck motor

Might be a little more but I doubt a lot, he posted some significantly sub 300 chassis numbers a while back

Hmmmm, that sounds like substantially more than 300 HP to me; I dynoed a similar motor with normal headers and CJ valves, and it made 400 HP.  I'd say he's at least at 350, and in that case the Performer RPM would show a significant advantage.  Based on that info I'd have to agree with hotrodfeguy, that he is leaving a significant amount of power on the table with the F427.

[My427stang]

I don't know what it really makes or how well he tunes, both would affect how well the RPM worked

On the FE Forum he posted "I dynoed 288HP and 343 TQ at the rear wheels"

At 15% loss that would be 338 so a little more than I thought.  However, before I blamed that intake for anything I'd see what the heads flow.

A C8AE-H has an exhaust port masquerading as an intake port with only 210-220 cfm.  I still think that whatever it gained would be lost down low, unless he did some big work to the heads, which I don't think he did

I am an absolutely an  RPM fan too, don't get me wrong, the difference on top on my 489 was incredible over an SD and an SM, but I also think it has very low speed tuning issues that would be compounded with a mild motor, stock converter, and tall tires or gears.

[jayb]

Chassis dynos are often down a lot more than the 15%-18% drivetrain loss, especially with an automatic transmission.  I'll bet he's got at least 350 HP at the flywheel, with the cam, carb, intake and headers.  I see your point though about those intake ports...

[fe66comet]

Head work, intake, cam and carburetor are my first mods I do. Mainly because you need flow to make anything else happen. Headers and exhaust soon follow.

[Drew Pojedinec]

I swapped a T intake for an Edelbrock RPM,  at first it seemed kinda down in power from a stop, and I'll admit, I was a lil put off.
After a bit of fussing and tuning, it runs just as well as the ole T iron beast from a stop, and I certainly gained a good bit on the top end.

My truck 390 is comparable to his in this regard. 
He isn't here to defend himself, but him mentioning that me getting 14-15 mpg (he claimed sub 10mpg) with this setup makes me think he has some sorta unaddressed tuning issue, be it timing or carburetor.
I know he went to someone to tune,  I never did that, I'm more of the "mess with this, go drive 5 miles, come back and tinker some more."  After a good 300 miles I might not have the most power, but I'll certainly have the most driveable vehicle.

[comet2]

i have an f- 427 to sell if they love them so much!! i have a rpm now . previously had port matched sidewinder, and holley street dominator . i strongly believe the sidewinder was the strongest runner and the lightest of the lot by a good margin.

[hotrodfeguy]

Well look at Bill's 390 on the other string. Obviusly that single plane intake is helping make some power with that same cam. It goes without saying if it works there and in a Galixie should also work in a truck. With the numbers Bill just posted I think his Galaxie would run circles around that truck 

[jayb]

i have an f- 427 to sell if they love them so much!! i have a rpm now . previously had port matched sidewinder, and holley street dominator . i strongly believe the sidewinder was the strongest runner and the lightest of the lot by a good margin.

My dyno data doesn't back that up.  The Sidewinder did reasonably well in my testing in the 400-500 HP range, but it wasn't as good as a Performer RPM or the single plane intakes.  The Performer RPM made 504 peak HP on my 390 stroker engine, the Holley Street Dominator made 499, and the Sidewinder made 496.  Also, the Sidewinder weighs 25 pounds, the Performer RPM weighs 27 pounds, and the Holley Street Dominator weighs 25 pounds.  The lightest FE wedge intake I've ever measured is the 4V tunnel port intake, which weighs 18 pounds.

[fetorino]

i have an f- 427 to sell if they love them so much!! i have a rpm now . previously had port matched sidewinder, and holley street dominator . i strongly believe the sidewinder was the strongest runner and the lightest of the lot by a good margin.

My dyno data doesn't back that up.  The Sidewinder did reasonably well in my testing in the 400-500 HP range, but it wasn't as good as a Performer RPM or the single plane intakes.  The Performer RPM made 504 peak HP on my 390 stroker engine, the Holley Street Dominator made 499, and the Sidewinder made 496.  Also, the Sidewinder weighs 25 pounds, the Performer RPM weighs 27 pounds, and the Holley Street Dominator weighs 25 pounds.  The lightest FE wedge intake I've ever measured is the 4V tunnel port intake, which weighs 18 pounds.

I may have been there that day.

[comet2]

hey,jay icant argue your dyno numbers all i have is an assometer when it warms up i have to change intake gaskets,so i can compare weights of the two again.the only reason i switched is because some butcher ported it and it developed a leak at a pushrod hole and started to run like an evenrude. also some of the sidewinders were cast in magnesium .

[jayb]

Wow, I didn't know they ever cast the sidewinders in magnesium!  That would be cool, and light...

[comet2]

yup, i saw one for sale at columbus swap meet 15 years ago . it looked like it was dredged from the bottom of lake erie horrible looking,pitted blackened the guy wanted 800 i thought he was on crack ! extremely light piece for sure!!! magnesium is 2/3 the mass of aluminum apply that math to what you said earlier. 25lbsx.66=16.5 lbs!!!!! maybe you had one!! this theory may seriously flawed my spelling also mag has to be passivated after it is in a molten state which creates a protective film as mag is highly reactive .thow water on molten mag makes hydrogen explosion!!! 

[machoneman]

Yes, Ford did do some mag intakes and here's a pic.

http://www.mustangandfords.com/techarticles/engine/mdmp_1210_ford_427_fe_build_big_blocks_on_the_dyno_real_iron_part_2/photo_09.html

Looking horrible is about par for 40+ year old mag parts since unless the parts were carefully wrapped in storage to prevent oxidation, old mag parts today would look just as described. Today though anyone lucky enough to score that intake has lots of trick metal coatings that would prevent said surface oxidation. IIRC, the very rare mag intakes were made for the GT-40 Mark II FE racecars (not NASCAR, where minimum weights way back then were almost 2 tons!).  Rare beasts indeed!   

[hotrodfeguy]

I also didnt know they had the SW in MAG thats cool. 

[fe66comet]

I would not use a magnesium intake as it is flammable. You already would have fuel and air all you need is a backfire and poof intake is a fireball. If you have ever seen magnesium burn it does it quite violently and fast.

[BH107]

I would not use a magnesium intake as it is flammable. You already would have fuel and air all you need is a backfire and poof intake is a fireball. If you have ever seen magnesium burn it does it quite violently and fast.

It takes alot of heat to ignite magnesium, and a backfire wouldn't do it. It would take a fairly significant engine fire to get it going. But if you are that scared of mag, never ride in an old Volkswagen as the engine block was magnesium.

[hotrodfeguy]

Just keep your foot in it then LOL
But back on track though any intake choice would be better than the F-427

[Qikbbstang]

I was in a junk-yard and found some Navy airplane magnesium wheels that were crushed/ruined. I picked up a couple football sized pieces and figured I'd have a ball reminiscent of high-school when a friends dad owned a machine shop that contracted for Grumen in the height of the Nam War. He'd smuggle home boxes of Magnesium shavings. Anyway I found magnesium chunks will spark like hell when you wail it down the street at night but as far as igniting it was a real dud just sparked and glowed nothing exciting.

[plovett]

In WWII during the night air war over Germany, pilots could see the fires on the ground from the British bombers and from the German night fighters which had been shot down.   They could tell if the fire was a British plan or German by the color of the fire.   Red-orange was British.   White-ish fire was a German plane.   The German planes burned white from all the magnesium in them.     That's what I've read anyway.   Call me Cliff.   

paulie

[Qikbbstang]

into the ports of either manifold and it's monsterous caverns that end up looking like funnels that feed to the manifold flange. Jays book shows this with a whopping 4650 and 4700 cc intake volumes.  You study inside a Perf RPM and the runners look to be the same H & W right up to the plenum area

[comet2]

hey guys if a particular intake costs 400 bucks and makes 10-15 more hp than a 75 dollar intake that can be improved with portmatch according to jays own words. which intake is the real POS !!!!  you will probably see more difference with weather conditions or fuel quality! i do have an RPM on a POS 390 with POS c7 heads because when you live in shebbyville thats all you can get!!!! BUT i have had a lot of fun with it for 20 years. and it still is running strong! knock on wood! what i am trying to say is if hot rod magazine mentions a slight improvement over an current part the current part is doomed and banished into oblivion!! then the shebbie boys find out and now their 305s are better and faster!! 
changing my previous mentioned intakes never made earth shattering differences so why pick on f-427 woudnt it be an improvement over a stock 2v for 75-100 bucks?

[ScotiaFE]

hey guys if a particular intake costs 400 bucks and makes 10-15 more hp than a 75 dollar intake that can be improved with portmatch according to jays own words. which intake is the real POS !!!!  you will probably see more difference with weather conditions or fuel quality! i do have an RPM on a POS 390 with POS c7 heads because when you live in shebbyville thats all you can get!!!! BUT i have had a lot of fun with it for 20 years. and it still is running strong! knock on wood! what i am trying to say is if hot rod magazine mentions a slight improvement over an current part the current part is doomed and banished into oblivion!! then the shebbie boys find out and now their 305s are better and faster!! 
changing my previous mentioned intakes never made earth shattering differences so why pick on f-427 woudnt it be an improvement over a stock 2v for 75-100 bucks?

I've never thought the 390 was POS. C7 heads will hold there own when tuned up.
It was the intake and logs that really sucked.
If you have a F 427 that you want to part with for 75 bucks I`m buying!

I think the F-427 has a great looking traditional appeal.
The RPM although works great is really not a great looking intake.
The Ed and Holley spider type have a great look.
Let`s face it, A great look is worth 50 HP.

[jayb]

Yes, let's not get too down on the F427.  There are better intakes out there, but with a port match the F427 is at least respectable, especially on ~400 horsepower engines.

[hotrodfeguy]

I think Bill's 390 is a perfect example of a F-427 would shoot you in the foot. HE MADE, 438-443 hp from 5600-6200, and 448-454 lbs ft from 3700-4000 with a 270s cam SD intake. now I think if you put that beloved F-427 on there it would not show such nice numbers on that 390. Just a hunch, But I am just a redneck with a flowbench and a few machine centers. Who happens to know how to weld cast iron.  It's better to be lucky than good I guess.

[Faron]

Having worked with Blair Patrick for a bit , and learning new things ( never too old to learn if your smart )I have see great power numbers from combos that most think would not happen , Not sure how a PI intake compares to a F427 , but I bet its close ( on a flow bench ) but like I said nothing is a given , Numbers ( flow ) are only part of the deal , a PI intake on a 390 ish motor making 530 + power , its not just an intake , the rest all factor in IMHO   

[TomP]

I actually swapped from an F427 to a Performer RPM on my ramp truck which i also raced.
 It made a huge differnce at low RPM and still made better top end. A dyno won't tell you anything about driveability testing at full throttle.  Going up a hill and not having to downshift in a 9500 lb truck easily shows the Perf. RPM advantage.
 Because of the truck 4 speed's really wide gear ratios i'd have to wing the stock, unrebuilt 428 bottom end to 6500 so it didn't fall off too badly in the next gear. 6500 was worth several tenths over shifting at 6000 even though the cam signed off below that speed. The Performer RPM was better than the F427 for that too.