Engine setback thought experiment??

Stangboy67 · Jan 13, 2006

My basic idea for my 67 is to do the Heidts or Rod and Custom front end conversion a bit down the road and from what I can tell, the cross member has to be placed quite precisely eliminating that as a possible engine setback opportunity. Then I noticed (can't remember where at the moment ) motor mounts that allow a few inches of front to rear adjustment.

Would setting the engine/tranny back using adjustible motor mounts help weight distribution? My first thought was yes as the weight is further to the rear, but then after a little further thought, my answers was no. The reason for my "no" was even with the engine set back in the mounts, the weight of the engine assembly is placed on the crossmember which is still located in the same position in the car, so no weight shift. Right??? or will there be some sort of leverage effect that will help, maybe shifting more of the "weight" to the tranny mount?

Route666 · Jan 13, 2006

It is where the mass of the engine is in direct relation to the car that matters.

Any leverage the mass of the engine has over the mass of the rest of the car is only changed if the position of the engine relative to the rest of the car is changed.

The force vectors that you will end up with, flowing through the mount, will sum to the same thing as directly connecting the engine to centre of mass of the rest of the car.

Otherwise people would be building wierd mounts that mount the engine wherever they like, connecting it to the middle of the car.

Stangboy67 · Jan 13, 2006

Route666, thanks for the reply!

So, if I understand you correctly (little slow this morning, been up 20 hrs and looking forward to bed) in my hypothetical example, the force applied on the adjustible motor mounts will be vectored through the stationary crossmember and have a positive influence on the weight distribution of the car, in effect transferring weight to the rear of the car, right?

Dark Knight · Jan 13, 2006

You can put the engine wherever you want, just use engine plates.. not a big deal.. The BB is my 68 is set back and down, lower CG. Pretty much all types of racing move the engine back and down, if it's legal

180 Out · Jan 13, 2006

The motor mounts you're probably thinking of are from Ron Morris Performance:

Here's a link: http://www.ronmorrisperformance.com/

LMan · Jan 13, 2006

It will shift your CG to the rear, but unless you are a roadracer or something similar, you prob won't notice it.

Stangboy67 · Jan 13, 2006

LMan said:
It will shift your CG to the rear, but unless you are a roadracer or something similar, you prob won't notice it.

This was going to be my next question. With the 5.0 in there now, I would not be able to move it much (back anyways) without modifying the firewall. Being that this is a daily driver (with only a bit of track time) I was wondering if it would make a noticable difference considering the work invoved (motor & trans mounts and cutting driveshaft)

180 OUT...those were the mounts I remember seeing, thanks. My plans also include dropping in a 351W based stroker and they may be handy to lower the engine assembly to get it to fit under the hood if that is an issue.

Dark Knight, I had not considered an engine plate as I assumed this was more of a race only type of setup. Being primarily a driver, does this transmit alot of vibration to the frame? Where do these bolt to the front of the block? I also thought this would be a bad idea since your moving the mounting point forward in the car, but if it all depends on CG rather than mounting location than this is not an arguement against that I guess.

Thanks for all the replies.

xoxbxfx · Jan 13, 2006

180 Out said:
The motor mounts you're probably thinking of are from Ron Morris Performance:

Here's a link: http://www.ronmorrisperformance.com/

lol... tcp whaaaat??

HistoricMustang · Jan 13, 2006

Stangboy67 said:
My basic idea for my 67 is to do the Heidts or Rod and Custom front end conversion a bit down the road and from what I can tell, the cross member has to be placed quite precisely eliminating that as a possible engine setback opportunity. Then I noticed (can't remember where at the moment ) motor mounts that allow a few inches of front to rear adjustment.

Would setting the engine/tranny back using adjustible motor mounts help weight distribution? My first thought was yes as the weight is further to the rear, but then after a little further thought, my answers was no. The reason for my "no" was even with the engine set back in the mounts, the weight of the engine assembly is placed on the crossmember which is still located in the same position in the car, so no weight shift. Right??? or will there be some sort of leverage effect that will help, maybe shifting more of the "weight" to the tranny mount?

Oh yes. These guys are going it but it is very hard to tell, just like the "expanded fenders".

www.cobraautomotive.com

HistoricMustang
www.historicmustang.com

Route666 · Jan 13, 2006

Stangboy67 said:
Route666, thanks for the reply!

So, if I understand you correctly (little slow this morning, been up 20 hrs and looking forward to bed) in my hypothetical example, the force applied on the adjustible motor mounts will be vectored through the stationary crossmember and have a positive influence on the weight distribution of the car, in effect transferring weight to the rear of the car, right?

Sorry for not replying sooner, I too was going to bed, but at night.

Others have answered it anyway - yes, moving the engine mass back will centralise the whole mass more. The amount though as others have said, will hardly be noticable.

The simplest way I can think of analogising it at the moment is:

Get a medicine ball, hold it between your forearms with your arms extended and shake side to side, note the effort it takes. Now hold the ball the same distance away, but in your hands, with your arms bent, and shake side to side. The effort will be the same, except it might be easier to hold it with your hands. So how your arms are held (the mount configuration) doesn't matter, just where the ball (mass of engine) is in relationship to your body (car's body).

The problem is with that analogy is that your arms have muscles which can probably work easier in one configuration than another, such as holding the ball in your hands, not just between your forearms, and then your bent arms will use your chest muscles better than straight in front of you, etc.

Hack · Jan 13, 2006

Stangboy67 said:
This was going to be my next question. With the 5.0 in there now, I would not be able to move it much (back anyways) without modifying the firewall. Being that this is a daily driver (with only a bit of track time) I was wondering if it would make a noticable difference considering the work invoved (motor & trans mounts and cutting driveshaft)
(snip)
Thanks for all the replies.

No, you probably won't notice. Now if you put in a motor that's more than 100 pounds lighter than the 302, you will notice!

If you're really serious about having a great handling car, try putting in a twin turbo modular 6 or a big OHC four with a turbo. That would be well worth the effort, and you won't have to hack up the body of your classic.

Edit: another method I highly recommend for improving the car's handling is to get yourself some driving lessons and seat time on the track. You are going to be the limiting factor much more than the car.

Stangboy67 · Jan 13, 2006

Hack said:
Edit: another method I highly recommend for improving the car's handling is to get yourself some driving lessons and seat time on the track. You are going to be the limiting factor much more than the car.

That is very true, and something else that is already on the to-do list, but not until the car is up for it (steering needs help!)

Route666, The ball analogy works and after thinking about your first post (after sleep) I understand what you were getting at.

I have been learning quite a bit since finding this site and forum a few months back. Lot of helpful and knowledgable people. Thanks all!

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