Mustang6713

What would you guys suggest a "safe" max horsepower range would be for an original 289 v8 and c4 transmission? My concern is the block, cast iron vs modern aluminum. I am planning to rebuild both the engine and the transmission to beef it up, but just wanted some thoughts from others.

The car won't be tracked at all, street only and won't be launched from red lights. Just want some more oomph under the hood without having to swap the engine out (I want to keep the car together with the matching numbers), the Edelbrock RPM Performer looked good to me for a top end kit, but again I am just looking for opinions from others. Thanks in advance

rtintwo

A stock C-4 in good condition is good for about 300hp. A built C-4 is good for ALOT more hp.

You dont need to have any concerns about the 289. It is the same design as the 302 and 351w that people are getting 350-500 hp out of.

With your goal of a fun cruizer with a bit more oomph the 289 and C-4 will do just fine for you.

Take a look at this link its a relativly inexpensive mod that will fit in with what your goal is. Combine this with a 4barrel carb, exaust and recurving the distributor to boss specs and you just might have met your goal.

http://www.mustangbarn.com/portmatching.html

Norm Peterson

The only block concerns involve its actual condition. As in no cracks and not already bored out to 0.030" over. These thinwall castings don't have enough meat to go 0.060" over, and even 0.040" over is considered "iffy" by many.

For a street driver with an AT and presumably a stock torque converter I'm not sure that I'd go with the RPM. I think a regular Performer with a small 4-barrel carb and a mild hydraulic roller cam would work out better. If yours was a stick shift, then I'd consider the RPM (and probably just a little bigger cam).


Norm

Mustang6713

I am definitely rebuilding the trans, but I might also switch to an AOD. I am planning on upgrading my carb to a 4 barrel, 600cfm or more, cam and some other stuff like heads. Staying with my original 289, how high could I get in horsepower before I would have to worry about it cracking or worse? Would it be possible to get over 400 without too much trouble?

JMD

The rumor is that a stock 289/302 block is good for about 400, or maybe 425 ponies... A stud girdle might give you another 50 safely enough.

As mentioned, C-4s can be built to be safely within limits for just about any "practical" naturally aspirated 289.

Norm Peterson

I'd guess most (good) blocks would be OK for that much, but where you'd find it with only 289 normally aspirated cubic inches would be up around 7000 rpm or so, and you'd be giving away some low end torque and driveability to get it. Your C4 probably wouldn't appreciate this, unless you incorporate a looser torque converter and/or deeper axle gearing, either of which would be a clear step in the direction of turning the car into a race car.

Just for reference, I looked up some 289/306 HP Shelby data, 306 HP @ 6000 rpm, torque peaks at 4200.

http://www.conceptcarz.com/vehicle/d...carID=7995&i=2

I honestly think that for a 289 street driver you'd be better off aiming a good bit lower on the HP scale than 400 and concentrate more on midrange torque. Keep in mind that a HR cam will run a little stronger up top than a flat tappet cam with the same advertised and 0.050" specs. Not all aluminum heads are huge race pieces - for example, I think AFR still has SBF heads in 165cc, which is plenty big for your situation.


Norm

2+2GT

You can get to 325 hp doing easy stuff in your garage, 350 if you want to go "solid" cam or convert to rollers. Getting to 400 is pushing it, and will really run up the cost. The C4 can do this, the 289HP used a mostly standard C4, with just a few tweaks, and a larger servo for solid shifting. It's available new.

Look at it this way, with 325 hp you can drive fast enough to scare your passengers. Since you aren't racing the car, 400 hp would be pointless, and cost you thousands of dollars.