4.6 modular v. 302/331/347

[Mike Thompson]

Newbie here. Just thought I'd chime in on the great Modular debate with some information.

1.) According to page 94 of the 2008 Ford Racing catalog "the new 3-valve 4.6 engine in the 2005 - 2008 Mustang weighs only 420 lbs dressed. The aluminium 4-valve 4.6's are listed at 463 lbs.

2.) Any Ford Modular V8 is 3"- 4" shorter that an SBC, LS1, or SBF.

3.) The accessories bolt to the block and therefore do not require brackets and special pullies etc.

4.) Unlike many Japanese OHC engines which use rubber band drives, Modular Fords use an advanced chain drive system to drive the cams, and are designed by Ford to exceed 200,000 miles.

5.) Many Modular Ford engines have steel cranks and all are crossbolted from the factory just like the 427 LeMans engine. Some even have forged pistons and H- beam rods to stand up to high performance needs.

6.) Ford has a new Modular crate program called the "Aluminator" offering all the goodies in one lightweight and competitively priced package.

7.) A Ford V8 is the ONLY thing that belongs in the engine bay of a GT40.

 

[Jac Mac]

" A Ford V8 is the only thing that belongs in a GT40"--Preferably one with inline valves & pushrods.

 

[Fran Hall RCR]

Amen!!!!!!

 

[Cliff Beer]

Ron and Howard, thanks for your thoughts - I'm sure you're absolutely right that I'm likely leaving a bunch of untapped horsepower on the table. And, definitely, I should get the car on the dyno to provide a starting point for subsequent comparison - a couple of the local car clubs here have "dyno days" coming up that I'll join in on that. The car certainly feels like it has 350 at the flywheel and maybe 300 at the wheels - according to the dynobutt.

The Mallory ignition is electronic and pretty basic but probaby OK as a system I would think - please let me know if you think otherwise. I don't know what the advance curve looks like unfortunately. Rev limit is set at 5,250.

According to the PO the Holley is a unique carb "for racing only" - it looks like a basic double pumper w/o chokes to me but I'm just starting to educate myself about Holley at this point and don't know a lot. As I know more about Webers I'm kind of inclined towards a conversion to downdraft IDFs/IDAs and don't mind spending the money on that at all as I love the originality and the tunability along with the expected 20 or so more hp.

I'm not looking for a ton more hp as I plan on giving a different 016 a go (AFC code with LSD) rather than waiting/hoping for a ZF to become available. If I could get 350 at the wheels that would be loads. As I will be pulling the engine and transaxle to switch to the AFC would you recommend I look at a different cam or different heads, or both? What cam or heads might be best for this engine without going to the extent of installing a stroker kit just yet?

Thanks gents, much appreciated.

 

[Howard Jones]

Well..... 350 at the wheels is going to be about 425ish at the flywheel. That's about 1.4Hp per inch. To get there I believe you will need to go above 10 to 1 compression and spring for different heads. My first choice would be AFR 185's with a close second the Brodrix equivalent CNCed heads. The cam will need to go big. Something on the order of 300 degree duration and .600 lift. And solid lifters. So you will be replacing, pistons, rings, heads, the entire valve train, Rods?, I am not a engine builder but I bet you are close to the limit on Ford stock rods, harmonic balancer, and a lot of ARP hardware.

On top of that you aren't going to get that kind of power at 6000RPMS either. I think you will need another 1000 revs at least. And that's getting close to forged crank revs. ANYTHING LEFT??

By the way, 350Hp at the wheels, that's a lot in a GT40. My money is on a little work in the heads you have and a good tune-up. Nothing wrong with the spark-box but I'm puzzled on the low rev limit. Your motor will more than likely make good power up to about 5800 like mine does. I have my rev limiter set to 6K and the shift light at 5900. It starts to blink at 5800. I would look closely at the carb. If you know someone who is good with holley's then have them have a look and see what you have. I used a 750 DP on mine because a guy I know who I respect told me that the Holley 750 double pumpers with mechanical secondaries really are very good right out of the box and would work fine on this light of a car. He was right.

If you have anything less (performance wise) than a RPM performer intake then ditch it for one. This would be a relatively cheap upgrade from something like a performer low rise type.

Lastly... I am certain to start a long discussion on weber's/ 4 barrels but I don't think you can expect a noticeable gain in power over a Holley. Some but not much. By the way I think they really look cool also. But the 2500 or so you will have into them and the rest of the parts it will take to make them work would get you a long way towards 350 wheel hp.

I forgot to ask about the muffler. There can be a LOT of power in a muffler. Can you tell us about your muffler. The stock old GTD muffler on my car cost me about 25HP at the wheels until I changed my exaust system over to a baffled straight through design. You should have a good look at exaust port match also. These heads have a bigger exaust port size than the standard iron Ford head. If the exaust flange on your headers isn't matched, my orginal GTD flange covered 1/8" at the top and bottom of the port in the X head, there can be a lot of power lost here also.

I have Comp's recomendation on valve train and cam for this motor if you are interested but it means fly cutting the pistons and a complete tear down of the motor to do so.