aussie head

[Anonymous]

hi all i was wondering, i have a 81 200 head that has been modified for a direct-fit 350 holly. Anyway, i was thinking of adding NOS or an aussie head. How much of an increase would the aussie give me? worth junking the money i have in my present head??
thanks for the opinions

 

[Anlushac11]

8)

Depending on compression ratio and what kind of carburetion you use, expect about a 35 hp bolt on increase.

 

[Anonymous]

so maybe about 50 hp for a full roller rocker set, double roller timing chain, and 2v head with 500 cfm holly and 10:1 compression??

 

[Anlushac11]

so maybe about 50 hp for a full roller rocker set, double roller timing chain, and 2v head with 500 cfm holly and 10:1 compression??

You should get about a 5-8hp increase from the full roller rockers. I would not expect a performance increase from the timing chain.

Add about 8hp for the carb

Roughly speaking increasing your CR by 1 point is about a 10hp increase.

So yeah, your pushing the roughly 50-55hp add on range.

Mustangaroo dynoed his stock 200 at 67rwhp. Adding the Oz 250 head put him about 103rwhp IIRC. Switching from a Holley/Weber 5200 to a Holley 350 cfm 2bbl boosted him to about 111rwhp.

 

[Anonymous]

so the 50hp increase is in addition to the HP i'm getting from my log head modified for a 2bbl?? because my real question is will i get a noticeable increase in acceleration from switching to a oz head from a modified log head that has been ported/polished and milled for a direct fit 2bbl?
my theory is if i add NOS on my log head i will need to do a direct port injection setup to avoid burnin #1 and #6 pistons, costing about $700. BUT if i buy the OZ head for $500, i could put on a plate system for about $350 without worrying about burning or leeaning out due to the better distribution of the oz head for a total of $850, with a better performance all around?
thanks for all the advise!

 

[Anlushac11]

8)

No.

If you take a stock log head 200 and dyno it you should get approximately 67rwhp.

If you take a log head off and install the Oz 250-2v head, with full roller rockers and a Holley 500cfm 2bbl you would add almost 50hp to that.

So roughly speaking 117 rwhp is not out of reason.

And yes, if you modify a Oz 250-2v intake for a 4bb, and install a plate type NOX system it should work. I recommend a 1" spacer if you have room and a wet NOX system.

The 1" spacer will promote better mixing before entering the runners and a wet NOX system will help reduce the chance for leaning out the mix if something goes wrong.

 

[AzCoupe]

No need to modify the manifold to a 4V, Holley offers a plate for the 2300 2V carbs. http://www.holley.com/HiOctn/ProdLine/Products/NOS/NOSNS/Powershot.html

 

[Anlushac11]

No need to modify the manifold to a 4V, Holley offers a plate for the 2300 2V carbs. http://www.holley.com/HiOctn/ProdLine/Products/NOS/NOSNS/Powershot.html

Come to think of it FSPP also offer the adapter. Buy from AzCoupe and help save a Kitten.

http://www.fordsixparts.com/Related%20Parts.htm

 

[Anonymous]

I understand that a oz head will add about 50 horses overstock
but has anybody dynoed a modified log head?
know that port and polish and direct mount 2 barrel is a step in the right
direction but how much?

 

[xctasy]

Mustangaroo has done some of the neatest dyno work on 2V's.

Stock 200's ran in at 67 hp at the rollers with a manual. Including tire rollong resistance, this is about 85 SAE net horsies at the flywheel, much less than the ~120 hp claimed gross at the flywheel.

The mildest 2V, still with a stock cam, fell in at the 105 hp mark at the bags, or 140 HP SAE net at the flywheel. Mustang aroo was using an auto, not a manual.

His son has a wild 650 Holley 4-bbl, and it has a good cam, and will be much stronger.

With the bigger Holley 350 on a 1.5" diameter hole log 200, its hard not to get a 25% increase. Afeter all, the carb is the restrictor, and the log intake isn't as bad as the 9 port Chevy 230/250 head, thats for sure.

My pick is a 2-bbl #2300 on a 200 Log will give about 105 hp, perhaps 115 hp if its a later large plenumb post 78 head. I'd sermise that the mounting of the carb 180 degrees to normal, direct onto a milled head, would be much better than the adaptor, as long as you didn't want to go around corners to quick. In tight left handers, the power jet and mains are exposed. At these lower (sub 130hp ) levels, the Holley 350 mounted this way is a disadvantage as the Weber/Holley isn't affected by this fault. Import 2600 and 2800 Capris used this carb turned through 180 degrees too, and it was fine.

In Australia, one one does 350 Holley to 250 Falcon log swops. All the non 2v heads had 1.5" intake holes, and a 350 Holley on an adaptor used to end up through the bonnet.

All opinion, no one has done the tests on hp. I'll bet someone at Cliffords or David and Dennis Schjeldahl at Sundog mob has. http://falconperformance.sundog.net/default.asp

Just remeber, no one has knowledge cheaply won with these engines. The experts who have gotten there hands dirty are the ones to seak.

What I'm prepared to say is that the head is a minimum of a 20% power boost on a hot log headed rebuild, all cam, carb and header being the same. Often 65% on a 200 1-bbl stocker, if the 2V has a Holley 350 cfm carb with stock cam and headers. With a 500 Holley, the limit is the cam, and I'll go on the record for saying a good 2V head on a 200 with a 264 dergee cam should hit the 160 flywheel hp mark with no trouble. Sort of like a turbo really.

 

[Anonymous]

I'll go on the record for saying a good 2V head on a 200 with a 264 dergee cam should hit the 160 flywheel hp mark with no trouble. Sort of like a turbo really.

Oh yeah!

running a 264 Dual pattern, with some porting and polishing... Roller rockers, 2300 carb, balanced and with a little TLC... I hope to up that to 170hp (maybe a tad more?). I found a dyno and am planning on running it after I break it in

 

[Anonymous]

You shouldnt have to big of a problem adding nitrous to your modified log head. Dan (Import Killer) has allready done it with great success, (Holley 2 Bbl adapter) and after I work out a few more things on my Stang, I'm going to bolt on a 100 hp kit also.

Proper head prep & head year selection, install larger valves, good port & polish, milling to raise the compression ratio & direct fit placement of a 500 cfm Holley 2 Bbl or Motorcraft equivalent is worth a good 40-45 hp on a log head IMO

Also,

There has been a lot of discussion lately about how a 350 cfm Holley 2 Bbl and a 500 cfm Holley 2 Bbl doesnt actually flow 350 and 500 cfm's respectavily because supposedly the 2 and 4 bbl are rated at 1.5 hg's and the 1 bbls are rated at 3.0 hg's.....

My Holley book says that the 1 Bbls and 2 Bbl's are rated at 3.0 hg's and the 4 Bbl's ONLY are rated at 1.5 hg's......anyone care to comment on this??

Later,

Doug

 

[xctasy]

The earlier book on Holleys by Dave Emanuel says the opposite. It's all achedemic BS, but lots of fun if you want to confuse yourself. From the posts on the carby mods you've done, I think you under stand the concepts of airflow much better than most.

Any way, all 2-bbls are rated at 3" Hg (~40 " H20, or around 1.5 pounds per square inch)).

All 4-bbls are rated at 1.5"Hg (~20 " H20, or around 0.7 pounds per square inch).

Apparently, if you place two 390 cfm quads on your Falcon, the flow drop would be rated at 0.75" of Hg, or a potential 780 cfm set up becomes a 552 cfm set up, with poorer peak air flow.

Why?These are rule of thumb pressures drops. Since pressure is acting in the dimension of flow area, the way to convert them is to take the pressure drop the carb is baselined at, and then divide or multiply the new pressure drop by the square root of the difference.

E.g If a good 350 #2300 Holley rates 350 cfm @ 3.0" Hg , then what is the flow at 1.5" Hg?

Divide 3/1.5, then take the square root of the result. Thats 1.414.

So a 350 cfm carby is really 248 cfm.

If you have a 390 cfm carb, is the 350 cfm or 500 cfm a better flow proposition? Who knows!

All I know is that 500 cfm Holley 2-bbls have been up to 350 hp on stock cars. That means they must be flowing lots more pressure than a stock six, some thing like 3.75 "Hg.

One other thing. For good peak power and drivablity, gas speed should be no lower than 250 feet per second. NASCARS have run for years with 650 cfm carbs which yield 650 hp. The peak gas speed is spread over a restrictor plate that is about 1 11/16 inches. The venturis are 1 5/16, IIRC, therefore there is a gross flow area of 5.41 square inches, or 0.0376 sqaure feet.

Since Flow is Volume time the area (Q = v.a) then normally a 650 cubic feet per minute carb would have a peak gas speed of some thing like 10.833 cubic feet per second, then the flow speed would be 10.833/ 0.0376, or 288 feet per second. But NASACARS flow in access of 780 cfm on there engines which have very restricted carbs. The actual gas speed is more like 350 feet per second. Little 500 Holleys on 350 cube 2-bbl stock cars are running up to the 350 hp level, and you can bet gas speed is well over the 404 feet per second level for the 1.375" venturis these carbs had.

Those Carter Duals you had on the Mustang were possibly ideal for producing power if someone had the parts and jets and dyno time to sort it.

Check out Whitteys posts. He's got the flow thing sorted fairly well.