Cylinder head upgrade
 

Folks, I'm currently running a set of TFS Twisted Wedge heads (standard exhaust ports) with porting and a set of Erson billet aluminum roller rockers. I'm toying with the idea of going to a higher performance head with raised ports. Since I would need to have a new set of headers fabricated, I would go with something a bit bigger than my current 1 5/8" tubes. Is it likely that I could get a manufacture-cnc'd port job that is optimum out of the box? My current heads were hand ported (don't know it that's good or bad). I'm running a Vic Jr. intake that has already been gutted a bit. I would have them installed at Southern anyway, so any issues about knotching pistons for valve clearance would be handled. I'm holding off getting my Demon 750 blueprinted until I decide on this upgrade. Any particularly exciting makes out there - Brodix, TFS-R, AFR 205/225 etc?

I guess it all depends on how good a job was done porting you current heads. If they were done very well, they may actually flow better than most heads out of the box. Odds are they were not ported that well, but you never know until you test them.

What type of power are you making now, with what engine combo, and how much more are you wanting or expecting?

EDIT:
If this is the 427W at 500+ Hp, I would say the heads are flowing pretty good. You could easily do worse. If you want much more than this, go BB naturally asperated or supercharge this engine, as it is.

%/ if you get the raised ports you will have to cut the body for clearance at the exaust pipes. Sometimes as much as 1 3/4 " . Something I didn't think of with my aussie raised port heads.The botom of the pipes are above the line of the botom of the body and the rear mount is above instead of below the frame mount. just something to think about with a painted car. **) Peter.

Olddog, I'm making around 400 HP/TQ at the wheels, so I'm really a bit shy of 500 flywheel HP. I don't want to move from a carb set up, so it will be hard to make significant gains without giving up street manors (it's a street car).

Peter, I would have Unique fabricate a new set of headers so the body exit location remains the same. I could probably use bigger tubes anyway. I look at the ported heads and the size of the header flanges, an I know I'm giving up something.

From the flow numbers I've seen Twisted Wedge heads flow better at HIGH RPM than a comparable set of AFR's. However, the AFR's flow better at virtually all rpms below that. Making them in my opinion a better overall choice, especially for the street. Unless your looking for MAX power at PEAK rpm, drag race application, I'd have to go AFR.

I don't drag race, so I prefer low-mid range power. I'm really stuck on the raised exhaust ports, which I believe means AFR 205 and 225s. They offer a CnC'd version and I'm wondering how they perform right out of the box. They might have to be ported further to match my existing intake, which has also been ported.

I sure was surprised when I began to look more closely at the flow numbers for various heads. Most often those numbers are max flow and as a result don't show the 'real world'.

For instance it is well known the Boss 302 were running 351C MONSTER heads. But to make them work and take advantage of the flow they had to be turning in the 7000 rpm range. When the smoke cleared it was found the motors simply could not tolerate that high rpm lap after lap and blew up. The big heads were dropped I believe after one season.

Likewise my High Riser heads will easily support 7000 plus rpm, but my cam profile is done around 6200-6400. While I love the original High Riser heads real world' says, medium riser would work as well or better for my current cam\carb setup.

I would think just going to 2" primary headers would be the biggest bang for the buck.

Tony;
I'm using AFR 205's and they're only raised a little. I ordered the car with 1.75" headers from Unique and they don't come near the body opening. If you get headers made I suggest you get them raw and polish them up yourself before ceramic coating as mine were a little rough. I can't tell you how good the combo works as I'm a ways from finishing and, with my travel schedule I don't know when I'll be done.
Bill Stradtner

As a long time Boss 302 owner I can tell you that these are primarily old wives tales. The Boss was introduced in 1969 after the failure of the tunnel port 302 in 68 with the specific mission of pounding the chebbie Z28 on the track and street. At St. Jovite that year there was a huge pile-up involving most of the 2 Boss factory teams (Shelby and Bud Moore). After this crash the Boss teams were left trying to piece cars together to continue racing and failed to win the manufacturer's championship. The 1970 season was a different animal altogether as the Boss team of Bud Moore (the Shelby team was dropped for 70) ran away with the title without even looking back. In 1971 the SCCA changed the rules allowing de-stroked engines to meet the SR2 (Trans Am) 5 liter limit. When that happened Ford scrapped the already planned 71 Boss 302 and introduced the Boss 351. Hey, if you can run more cubes then that is the way to go. The only factory that was left in T/A in 71 was AMC, so guess who won. The Boss 302 was a hit on the track and on the street on many different levels. A major magazine even took one road racing with a full interior and loved it. I will say that the Boss is no tractor, you don't lug it around at 1500 RPM and expect it to perform, but you don't need 7k to do either. Although I must admit that the sound of a Boss engine screaming at 7k+ will send chills up your spine. A big cube version like mine is even better. If you need more info on how canted valve engines perform, look no further than the Engine Masters Challenge where the goal is power over the entire RPM range, not just peak HP numbers. You won't find any inline valve (Windsor) heads there at the top, it just doesn't happen. Last year 4 of the top 5 were all aftermarket C headed Ford small blocks. The only non Ford was the Jon Kaase Pontiac, bet he wished he'd stayed with a Ford! Remember this is average TQ and HP from 2500-6500 not peaking at 7k with nothing under it.http://www.popularhotrodding.com/eng...esults_friday/
Just thought I'd do a little myth busting!:D

Steve

Engine Guru
 

Hey tony ill give your the name of my engine guru iv known Kevin for at laest 25 years he is a master machinist and head flow tech is his specialty K@M Machine 816-353 4422 tellm Bill Hughes told you to call ,this guy know s his stuff he,s built a lot of championship engines here in the mid west over the years including mine .:cool:

The original BOSS 302 Cleveland heads are no comparison to the modern CHI heads used in the Engine Masters challenge. The new CHI heads come in a wide variety of port sizes, combustion chamber volume, flow characteristics etc. CHI have much better lower rpm flow chararteristics than the standard Cleveland head. Engine Masters measures h.p. from a low rpm range up, the original C heads didn't even 'wake up' until 4000 rpm. Cam profile would also be a huge factor in the Engine Masters challenge (as well as quench). Todays modern cam options and a much better understanding of quench makes for a CHI design head totally unlike what was available in 1969.

Myth Busting? Maybe, with some qualifications required. :D

Come on now, the CHIs have at least as much in common with the older C heads as AFR, Dart, etc, etc, etc, have with older W heads. Compare apples to apples and .......well you get the drift. My main point was that C heads in general make more power over a broader RPM range than do W heads. My iron C heads flow 335 cfm on the intake (only about 200 on the ex. though) and that's the old heads but with allot of work and of course the big inch block does pay off. The CHIs and to a lesser extent the Edlbrocks, make great power over a large range right out of the box. If you're comparing aftermarket heads (I mean jeez, were talking about raised ex. port Darts even) then due diligence may pay off big time. If you don't need the power and you just prefer the look or packaging of inline heads then I say go for it. If on the other hand you want the power, then to randomly dismiss canted valve heads based off of old wives tails or misinformation from the 60s or 70s is just silly.

The point seems to be, it's more than just a name that counts when it comes to heads, choose wisely for your intended purpose. Port configuration, flow at various rpms, intake\exhaust.

Chossing the right configuration for your heads is a lot like choosing the right cam profile. Comp Cams are great (the name) but they make a LOT of different 'profiles' for the same engine.

Perhaps a nice set of CHI 3V heads over 4V heads might be a good choice, depending on what your trying to do (road race, drag race, street). :D

It is now days accepted, as fact, that big ports are bad for low end torque, and only good for high rpm big cubic inch motors. The Boss 302 stands in sharp contrast to todays thinking. Sure people remember that the Boss 302 was sluggish at low rpms, but why was it so? A 290 deg duration flat tappet cam shaft, a 780 cfm carb, and (I think, but not certain) a single plane intake, all are a sure fired way to get poor low rpm torque. It is my opinion that a modern roller cam with duration of 220 intake and 230 exhaust, with a good single plane intake topped off with a 550 cfm carb, and a Boss 302 would pull hard from 2-7K. Just an opinion.

Big blocks, back in the day, with huge ports compared to small blocks, generally were known for low rpm stump pulling torque. Yet today many will tell you that it doesn't work. Why were hemi engines with even bigger ports and valves able to run on the street? By todays common wisdom they should have been hidious dogs on the street. I don't think so!

Me, I wish I had a Boss 302 to play with.

I have one of the first set of Twisted Wedges and they were worked to flow ~250 @ .400 and 280 @.500 and they are on my 427W (also one of the first CHP kit motors). The TWs work exceptionally well with a power peak at around 5800 rpm (I limit the res-line to ~6200) with Custom Comp XE Hydraulic and a Ported Victor Jr. To get big improvements in power you need to see some pretty significant gains in the MId-Lift flows, the valve passes through 1/3 to 2/3 lift TWICE but through the peak only once and for a comparatively small number of degrees. If I were to do another set of heads I'd look at the Jegs/Kaases but in my case I'd have to upgrade the whole bottom end to a forged crank to really be comfortable with heads good for another 500-700rpm. I wanted my 427 smallblock to feel like what an all aluminum big block 427 would feel like, wall to wall torque in any gear with a decent but not statospheric RPM range.

Rule of thumb is you need 4.1cfm per HP per Cylinder, so I figured 280 is good for at least 520-540 potential HP (if you use enough cam and compression to get it) which is right at the limit of where I'd put a stock block anyway. To go to 300-310cfm heads I don't have enough short block to hold the extra power (and Heat) anyway. Remember this one was built when aftermarket blocks were only in our dreams

As for headers, 1 5/8" is too small IMO for the 427 especially if they are coupled to the 3" small block style headers. I run a 1 7/8" with a 3 1/2" collector, I do this for the same reason as the Vic jr and the 800cfm carb, low end and mid range torque can be borderline excessive with 427" in a lightweight car, by moving the torque peak up to the 4000-4200 range and it's essentially flat from 3000-5200, so it's right itn te fat part of the curve at your shift recovery points. So it depends what you want but if the .200 to .400 lift numbers aren't a big improvement over what you have and you're not running a big roller to take full advantage of the peak flows, you might not gain as much as you might think in terms of average torque (what you drive) or peak power. The header change alone might give you better overall bang for the buck than doing both the headers and the head swap IMHO.

Wize, thanks for the insight. I've already decided to upgrade the headers. I'm also scrapping the Mighty Demon for a Holley HP carb. I am inclinded to stick with the Trick Flows for the time being.

I love hearing you guys stick up for the B2's. Me, I am happy with my little 331 yates headed motor. Runs on pump gas, a little strange around town but loves the open road. It only made 580hp on the dyno but then again, it's a small motor. Who is CHI? :LOL:

John