Stroking Motor, 1999Mustang Cobra, Is It Worth It?

RedVenomSVT99 · 03-01-2009

I have a 99 Cobra and was thinking about strokeing the motor. Is this a good idea and is it worth to do. What are the cons and the pros to this???

beetlejuice · 03-01-2009

pros to stroking an engine would be increased displacement, increased torque, more power at lower rpms.
cons would be possibly having to grind the bottom of the cylinder bores to accomodate the rods new location, possible increased vibration(usually cured with the right balancer), potential cost of the build.
If it's a bolt in stroker kit then it should be relatively cheap and simple for a rebuild.

Brutal Metal · 03-01-2009

I wouldn't do it, you already have a solid foundation with the Forged Cobra Crank, bore the cylinders .020 over to get a few extra cubes and throw in a good set of forged rods and pistons.

beetlejuice · 03-01-2009

I totally agree with Brutal Metal on NOT doing the stroke. A Cobra engine is awesome in and of itself and like he said it already has a forged crank. I'd do what he said or just get a nice bolt on supercharger after doing a rebuild.

98SVTSnake · 03-01-2009

Quote:

Originally Posted by beetlejuice

I totally agree with Brutal Metal on NOT doing the stroke. A Cobra engine is awesome in and of itself and like he said it already has a forged crank. I'd do what he said or just get a nice bolt on supercharger after doing a rebuild.

I agree to. the 4.6 4V cobra motor is a beast

If it needs a rebuild do a bore job and put forged parts in it and take the money that you would of spent on the stroke job and spend it on a S/C on it and hang on

that is what I'm going to do to mine when it is ready for a rebuild. but I have a lot of miles be for that only have 83,000 on my motor.

Geraldd · 03-01-2009

I don't think I would stroke because as Brutal Metal said, You do have a great crank. I would change the rods and pistons however I wouldn't bore the block unless it's nessaccery to do so. However I would go to a higher compression ratio, Let's say a 9.3 to 1 and just get my block honed to get the glaze off the cylinder walls and save that bore for a later day. Keep the cylinder walls thick as possible and run as much boost as you can providing good gas is available.

beetlejuice · 03-01-2009

Yeah, it might be best not to bore it unless absolutely needed. It is a Cobra block first and boring does take away metal and strength in between the cylinders. If you're going to run a supercharger at any time in the future then go with a relativelky low compression ratio.

RedVenomSVT99 · 03-02-2009

Thanks for all the advice. I think im juts gonna replace the internals and not do a stroker kit. The engine has 84,000 and change on it right now should i just buy a supercharger first and wait to replace the rods and pistons or do that first so i can put some serious boost on it.

Brutal Metal · 03-02-2009

I had to bore mine .020 cause Cylinder #7 got scored due to the infamous spark plug backing out of the head (you know coil pack explodes into 50 pieces and all the broken spark plug ceramic does a dance with the piston and rings, no fun, haha! The whole rubber coil boot got sucked into the motor too, me and my engine builder have NEVER seen anything like it, check the pic, pieces are stuck in the valves)
And I would agree that boring the cylinders isn't necessary if everything looks A OK, just use standard pistons,but I wouldn't think it would weaken the block too much cause your actually honing the sleeve insert? And 020 over isn't like a BB Chevy 060 over, ha!
If a guy does do a rebuild on their 4.6L 32V and never intends to put a power adder on I would recommend the Stock Crank with quality Forged Pistons, Rods, and Fasteners with a 020 overbore.
I FOR Sure felt the difference, my New powerplant is getting quicker ever day of the break in, I'm at about 1400 miles since the build!

<img src="http://www.allfordmustangs.com/forums/svt-cobra-tech/http://img6.imageshack.us/img6/922/svtcobra003sd5.jpg" alt="Image Hosted by ImageShack.us"/>
<img src="http://www.allfordmustangs.com/forums/svt-cobra-tech/http://img10.imageshack.us/img10/343...obra005tk5.jpg" alt="Image Hosted by ImageShack.us"/>

Brutal Metal · 03-02-2009

I had to bore mine .020 cause Cylinder #7 got scored due to the infamous spark plug backing out of the head (you know coil pack explodes into 50 pieces and all the broken spark plug ceramic does a dance with the piston and rings, no fun, haha! The whole rubber coil boot got sucked into the motor too, me and my engine builder have NEVER seen anything like it, check the pic, pieces are stuck in the valves)
And I would agree that boring the cylinders isn't necessary if everything looks A OK, just use standard pistons,but I wouldn't think it would weaken the block too much cause your actually honing the sleeve insert? And 020 over isn't like a BB Chevy 060 over, ha!
If a guy does do a rebuild on their 4.6L 32V and never intends to put a power adder on I would recommend the Stock Crank with quality Forged Pistons, Rods, and Fasteners with a 020 overbore.
I FOR Sure felt the difference, my New powerplant is getting quicker ever day of the break in, I'm at about 1400 miles since the build!

http://img10.imageshack.us/img10/343...obra005tk5.jpg

http://img10.imageshack.us/img10/343...a005tk5.th.jpg

<a href="http://www.allfordmustangs.com/forums/svt-cobra-tech/http://img10.imageshack.us/my.php?im...obra005tk5.jpg" target="_blank"><img src="http://www.allfordmustangs.com/forums/svt-cobra-tech/http://img10.imageshack.us/img10/343...a005tk5.th.jpg" border="0"/></a>

Brutal Metal · 03-02-2009

Sorry about the double post!

RedVenomSVT99 · 03-03-2009

Wow thats crazy never heard that before... Im just gonna do standard size pistons with forged internals then put on a power adder im leaning towards a procharger at this point but not 100% certain yet.

Brutal Metal · 03-04-2009

It actually happens more than you'd think, my friends shop has had over a dozen 4.6L Stangs through the years that had a plug back out of the head. Ford didn't tap enough threads into them (4), they didn't do a recall cause it would have cost Millions.
In 03 8 threads were put in the heads so the plug had more to bite on. I'm not at all trying to be doom and gloom, just explaining what happened to me. A piece of advice though, if you feel a significant mis don't just drive around hoping it will fix itself, CHECK those plugs!
And DAMM a ProCharger with a 99 Forged Cobra Motor, can you say NECK SNAPPING POWER!

RedVenomSVT99 · 03-04-2009

I dont want that happening to me should i have them re-tap the spark threads to 8 when its rebuilt?? And yea i cant wait to finish this car its gonna take a while but when its done its gonna own around here corvette killaa and those pain in the a$$ srt8s

Brutal Metal · 03-04-2009

ABSOLUTELY I would recommend having that done, have a quality machine shop Helicoil the spark plug housings!
My guy does it to every set of heads he pulls off a 4.6L doing a rebuild.