Moving the iron lump back?

On the Rustang, we are considering moving the lump. If the engine is moved back 3" it shifts it considerably back over the K member.

This will require, firewall modification, engine and trans mount modifications, maybe trans tunnel modifications. Minor throttle, clutch cable changes.

The weight movement should help balance the car.

Is it worth the work?

I have heard from both camps and the balance difference is not huge but in a front heavy car it should help.

It is not the only way we are planning to move weight backwards.

Steve

Daily driver? Or dedicated track car? That'd make the decision for me.

The engine is coming out anyway, needs more oil pan and a K member is going in

Why not move it even further back and make it midengine with a transaxle?

Put it in the passenger seat.. If your gonna go go all out.

EvanB wrote: Why not move it even further back and make it midengine with a transaxle?

Not an option for $2014, only thinking of this as the engine is coming out anyway. No way I can budget a transaxle.

PRE-EDIT: I haven't had any coffee yet, so this is probably over-complicated, and errors are not unlikely...

Of course the real question is "how much faster will this make it?", and I have no idea... But I wonder whether it's worth sketching out the math to get a little feel for the scale of the change?

What can we say for the combined weight of the engine and trans? I'm going to use 550 based on this and some inexplicable fudge factor.

Any idea what the thing weighs all-up?

Wheelbase is... 100.5". I'm going to take the Internet's guess of 27xx pounds and make it 2600 for the gutting.

So if you (550 / 2600 =~ 21%) of the car's mass and move it back 2.99% of the wheelbase, I believe you'll see 2.99% of 21% taken off the front wheels and added to the rear: .0299 * .21 * 2600 =~ 16.3 pounds.

Actually, now it dawns on me, we didn't need to involve the car's mass. Moving 550 pounds 3" back on a 100.5" wheelbase will move 16 pounds off the front axle and onto the rear axle. Where that becomes more meaningful is thinking of the proportion of the car's weight that is: 0.62%, which given the Mustang's almost-exactly-100" wheelbase means the CoG's been moved back about 0.62"

Why not move it back as far as you can without doing anything to the firewall, them work on moving the front wheel center line forward through the mounts and the A arms. That sound like much less work.

Also what about moving the radiator to the trunk?

Hey, it's way simpler to get the same value (I think) by taking:

(engine mass/vehicle mass) * engine movement = CoG movement

(550/2600) * 3 = 0.63 (there were multiple opportunities for rounding in the more circuitous calcs)

Ford Racing had a special front subframe that moved the wheels forward on the SN95(?). Different fenders, etc required. Maybe find some pics/specs for an idea?

Adrian_Thompson wrote: Also what about moving the radiator to the trunk?

That is already planned out, the free SN95 aluminum radiator will work out after all

Gearheadotaku wrote: Ford Racing had a special front subframe that moved the wheels forward on the SN95(?). Different fenders, etc required. Maybe find some pics/specs for an idea?

Hmm, I have a tubular K member that is already going into the car, and we already need to weld engine mounts, this idea shows promise. Fender flares can hide a lot of sins.

Do you know what the Weight distribution is now and what you'd like it to be? I think Ransom is right to make any major change in Weight balance of the car you are going to have to move the engine pretty far. Using his numbers even correcting for a 55/45 F/R weight distribution you would need to move the engine nearly 26" back to get to 50/50 which probably would be worth it but that's pretty dang far.

In reply to nocones: anything we can gain helps.

We will weigh engine when out of the car.

We are moving the radiator, around 50lbs relocated.

We will find more weight to get off the front end.

It might not be perfect but it all adds up.

Do you want more rearward weight bias?

Do you want the wheelbase longer?

Do you want the wheelbase shorter?

Any of the above can be combined, with as little, or as much visual impact as you'd like. Moving the rear axle forward might be a better way to do it as I would (wildly) guess that a shorter wheelbase would be better than a longer one for autox.

Are you trying to keep this under the Challenge budget cap? If not, a change to an aluminum block and heads and such would probably help a bit.

pres589 wrote: Are you trying to keep this under the Challenge budget cap? If not, a change to an aluminum block and heads and such would probably help a bit.

Coming back for $2014 for the 4th time due to schedule change, we may bring 2 cars yet.

No large budget items can be included.

tuna55 wrote: Do you want more rearward weight bias? Yes Do you want the wheelbase longer? To gain better balance Do you want the wheelbase shorter? If it can be done cheap and gain better balance Any of the above can be combined, with as little, or as much visual impact as you'd like. Moving the rear axle forward might be a better way to do it as I would (wildly) guess that a shorter wheelbase would be better than a longer one for autox.

I might be able to do this fairly easily too, I will do some checking but what concerns me is the driveshaft modification (cost) and 4 link pick up points .

Hint, I can use challenge friendly aluminum heads, 70lbs is a LOT.

In reply to aussiesmg:

I was thinking that you could move to an aluminum 5.3 L-type V8 but then there's getting a trans behind it and making this change at budget.

I would drop a couple of hundred HP to go to a 5.3, no thanks, besides no domestic sounds better than a wound out 408.

aussiesmg wrote: I would drop a couple of hundred HP to go to a 5.3, no thanks, besides no domestic sounds better than a wound out 408.

Your car does sound absolutely bad ass...

aussiesmg wrote:

tuna55 wrote: Do you want more rearward weight bias? Yes Do you want the wheelbase longer? To gain better balance Do you want the wheelbase shorter? If it can be done cheap and gain better balance Any of the above can be combined, with as little, or as much visual impact as you'd like. Moving the rear axle forward might be a better way to do it as I would (wildly) guess that a shorter wheelbase would be better than a longer one for autox.

I might be able to do this fairly easily too, I will do some checking but what concerns me is the driveshaft modification (cost) and 4 link pick up points .

My Dad had a friend who was crazy. Not in a "fun to be around" kind of way, more in a "holy crap, is he licking the sidewalk?" kind of way.

Anyway, crazy bud totally shortened his own driveshaft by welding very carefully and using clamps on an old piece of angle iron. Just a thought. It isn't that stupid on the driveshaft to assume you can do it yourself.

He also tried to make a two stroke 350, but that's another story.

With a rear hump sump, as you move the engine back and/or subframe forward, can you lower the engine as well? that might take some molten metal to make a low profile sump, but that has to be worth looking at at the same time as moving it rearwards.

If you've got the subframe out and are modifying it are you going to work on the geometry as well? There are details in the old Mathis book, I've got a copy somewhere.

Adrian_Thompson wrote: With a rear hump sump, as you move the engine back and/or subframe forward, can you lower the engine as well? that might take some molten metal to make a low profile sump, but that has to be worth looking at at the same time as moving it rearwards. If you've got the subframe out and are modifying it are you going to work on the geometry as well? There are details in the old Mathis book, I've got a copy somewhere.

We have done a lot to get the geometry right. Both of the Pro drivers at the Challenge commented on how well it turned, especially for a Fox. We will try to gain some more caster and camber, but no more than 1 degree of each at this point. Our current settings are 2.5 degrees of both caster and negative camber