ok guys,i have a 200ci,bored 0.30 over.a 264h cam.2bbl holley 350cfm carb,log head intake ported,pertronix ignition.a 4 speed tranny off a 6.and 3:55 much hp am i looking at????jw,it would be fun to know,since the 200 came with 120hp stock.
Be very cynical about the factory 120HP claims. What's your compression ratio? That will greatly influence power.
i really don't know
.but say i did have a 9:1 ratio,what's a good estimate on hp??
Hey KickinSixer,

The 120HP value is a gross number. In 1966 the book said 120 @ 4400. In 1972 the industry began publishing net HP, basically flywheel HP as installed (potential false advertising issues got their attention). This is the method used today. So, for an apples-to-apples comparison you need to startwith this number - 91HP @ 4000. If you go to the Falcon Performance site ( you will find a compression calculator that also estimates HP at various compression ratios, RPM and volumetric efficiency. If you change the deck clearance to .030 and use 75% VE at 4000 you will find an estimated 93HP. This is an excellent baseline for the 200 I6. Changes that impact VE (header, carb, porting, ignition, cam) will improve the VE at each step. Higher VE, more HP. Also, better VE allows more RPM. RPM and CR also add to the equation. as an example, assuming you have 9:1, that you have increased your VE to 85%, and can now run to 5000rpm, the calculator says 141 NET HP. A long way from 91. If you are running a lite car (2800 lbs is easily done), your power to weight ratio is significantly better than a "A" code 289.

Food for thought. Have fun with the calculator.

It's not just the HP that matters.

Torque is important, too. If you visit the Big Six forum, you'll find posts from people whose Torque almost is double their HP. The Frenchtown Flyer makes use of the 300 six's tremendous torque to beat a lot of V8 drag racers.

While the 200 doesn't make the same levels of torque and HP as an industrial engine like the 300, it can be built up to be sprightly, powerful and fuel efficient. Make no mistake, it will never beat a built V8 (except for the Argentinian TC racers), but can be hopped up to take the average SBF by surprise for quite some distance.

A six is not a substitute; it's a motor with its own pedigree. There are plenty of famous British and Australian six engines (and the odd German one) - you are in good company.

Cheers, Adam.
Mustangroo's dyno results were around 105. However, he had an aussie head. For the most part I believe his engine is stock save for headers and an ignition upgrade (Mustangroo please correct me if I'm wrong). A bone stock 200 should produce around 75 maybe 80 horses at the wheels. So his head upgrade was good for about 35 horses. As far as I know the head was stock. No valve enlargements or performance valve jobs, stock rocker assembly, stock cam, etc....

Sounds like you have many other mods but with the log head I don't think your going to make anymore then mustangroo. Cam's, bigger carbs and all that will not do much if your head is already a bottlekneck. Anyway if I had to guess my money would be on 85 - 90 horses at your rear wheel's. A head swap with all the other upgrades you already have would probably get you close to 120 or so.

Get that thing on the Dyno. That is the only real way to see what you got. I would be surprised though if you busted 100.
What year head do you have (large or small log)? Also, how is the 350 mounted, w/ an adapter or directly to a modified log?

If I had to guess, depending on the above info and the info you have supplied, you are in the 140-165 range, which is stock 289 territory. You'll also be able to eat a few 302's as well, IMO.

I thought a bone stock 200 was more like 65-70 hp at the wheels. anyways not much at all

i once read that you advertise horsepower but drive torque. It is the torque that plants your ass back in the seat and that is what you want for driving around town

I also have a 2v head that is currently being put together and the car is being painted. I plan to have it dynoed prolly end of april - mid may.
I can't wait
will keep you posted
Don't worry too much about horsepower. With 3.55 gears and a five speed along with a freshly built 200 or 250 you will be haulin ass. I'd bet you'd beat almost any automatic/small V8 old car that you'd meet on the road. Youd probably beat most of the 3 speed cars out there as well.

Definitely get a T5 though, don't putt around with the other manuals out there.
Hi all,

For the record, a stock 1967 200 I6 Mustang was dyno'ed at 67 rear wheel HP by AK Miller a number of years ago as a baseline for mods developed by AK. As noted earlier, Ford stated the net HP of this engine as 91 @ 4000rpm. This appears to be support the common view that the drive train will absorb 25hp. Mustangaroo's 105 rear wheel hp was obtained with a Holley 5200, header, upgraded ignition, 1.6 adjustable rockers AND a 2V head. Add the 25 back and you have 130 at the flywheel (net HP) without a cam. How much of this increase you can allocate to the head is yet to be determined. Someone will have to dyno a car with a 5200, header, ignition, and 1.6 rockers before the value of the 2V head can be stated. However, if you want a guess, Clifford has advertised for years that their carb, header, and ignition upgrade is worth 25% at the rear wheels. I can state from personal experience that the 1.6 rockers make a difference. So, for the sake of discussion, let's say 30% total. 67 x 130% = 87. Add back the 25HP and you have 112 at the flywheel (net HP). So what is my point, I don't think it rational to assume that a 2V will add 35HP to a stock car. 18 to 20 is a more reasonable expectation. However, we will not know until a vehicle with the appropriate mods is dyno'ed.

Torque vs HP. I agree. The way I heard it was race HP, but you drive torque... I like a strong bottom end. Torque has been high on my list of priorities with all of my mods. Second is weight control. Lite weight and lots of torque is fun to drive. It leaps across wide intersection in a single bound. Sorry, couldn't help myself.

My 2 cents - Steve
Soundz like you smoke tires too Steve. I agree with what you say.

An early 'Stang is trying real hard to top 2700 lb, about 1000 less than a 2003 Pony. The right cam, carb, head and gearing, a little six spins like a top and will last a long, long time.

My figures are: Take rwhp, multiply by 1.29 for a T5 or good manual trans, and 1.33 for a good auto. Then that gives you SAE Net flywheel horsepower. All the I6's have a huge factor of safety, and it's not hard to double the rear wheel hp with a combination of the mods the guys on this site have been working on. I've seen specs on a practically stock 196 flywheel hp Weber carbed cross flow 4.1/250 six in 1987, and there is no reason why a good flowing cast iron non cross flow 3.3/200 US six can't hit that figure.

Forget V8's, get wise and get modifying!