There's a new (Marin County) Sheriff in town
Mar 14, 2012 17:23:18 GMT -5
Post by sigmfsk on Mar 14, 2012 17:23:18 GMT -5
I was looking at this "before" pic of blusmbl's car:
from
bluesmobiles.proboards.com/index.cgi?action=gotopost&board=owners&thread=616&post=3544
and it struck me how close the rear of the block was to the firewall. Recall this pic, showing my trans/motor simulant lowered to provide the same ground clearance as stock (with dry sump pan)
It seemed to me that just lowering the motor, leaving the harmonic balancer bolt in the same fore/aft location, moved the back of the block away from the firewall, so that the transmission/engine combo could then be moved rearward.
I could move it back 5":
I read this thread about the benefits of engine setback vs. lowering:
www.camaros.net/forums/showthread.php?t=34317
and there were interesting items such as:
> Smokey Yunick always maintained that it was far better to LOWER the
> engine vs moving it to the rear. Accomplished the same thing, just
> better for the amount of work you did.
and
> I moved the engine back about 2 inches in my circle track car to gain
> rear weight. Once I was on the scales after it was done. It was only
> worth about 1/10th of a percent and a few pounds.
and
> I've heard that moving the battery to the trunk is equivalent to moving
> the engine back 8"
I'm not moving the battery to the trunk, so I don't care much about front/rear weight balance.
I suppose that moving it back would result in the car having a lower polar moment of inertia, which would result in quicker cornering ability
> ...you want to keep the car's polar moment of inertia low for quicker
> transitional handling. To visualize polar moment of inertia, imagine trying
> to twist a set of dumbbells back and forth from the handle. Sort of
> tough, right? Now imagine trying to twist the same weight in your hand
> if it was a compact sphere. This is much easier. A car, with its mass
> located closer to its center, will respond to steering input faster.
www.turbomagazine.com/tech/0806_turp_hows_and_whys_of_battery_relocation/viewall.html
Which seems a nice benefit. But one immediate benefit to my application is that moving the engine rearward 5" would result in me being able to move the steering rack back 5", which would mean that it wouldn't be so far forward of the front wheel centerline.
Here's a pic to show what I'm talking about:
Notice how the rack is forward of the centerline. I read in "The Sports Car & Kit Car suspension & brakes high-performance manual", page 29, that moving the rack forward like this "although not ideal...not as bad as it might appear...this particular aspect of rack positioning isn't overly critical, except perhaps at the extremes of lock".
from
books.google.com/books?id=smKpTCICw8QC&pg=PT29&lpg=PT29&dq=his+particular+aspect+of+rack+positioning+isn%27t+overly+critical&source=bl&ots=BBBSadWfTJ&sig=F5AM48lRbPgYhCbyvHuFX_4dsyo&hl=en&sa=X&ei=tRFhT5imC-rY0QHW5qzSBw&ved=0CCAQ6AEwAA#v=onepage&q=his%20particular%20aspect%20of%20rack%20positioning%20isn%27t%20overly%20critical&f=false
But still, it seems that moving the engine rearward, if it wasn't difficult, would provide gains all around.
The back of the passenger valve cover is about even with the back of the block:
while the driver side head is about 1" forward of the back of the block:
This maps nicely to the firewall, as the firewall curves forward by the driver head.
Fore/aft is limited by the firewall on the passenger side (because it has the huge a/c box behind it). If I have 3/4" of clearance between the passenger head and the firewall, the driver head will hit the firewall a bit, but there's nothing inside the car that would be impacted by just notching the firewall and moving it inside a bit.
Inside, up/down is limited by "globey". This guy:
that mounts under the giant a/c box. Here's how it looked in the Fury originally:
the trans tunnel rammed right up to it:
Here's a test-fit with the a/c box without globey:
and with globey:
It looks like globey doesn't really impact trans positioning much. I opened the a/c box, and it looks like if the trans hit the a/c box, I could notch the box if necessary, as it's just open air at that place:
and I could notch globey if necessary, so the limiting factor seemed the front forward bottom edge of globey. Keep the front face of globey correct.
Step 1: Mark this position with the trans jack/scissor jack combo:
step 2: remove globey and a/c box:
then add in replacement wood form that mounts to a/c box holes in firewall:
add in form that bolts to seat location:
then rest the third piece on top that shows the globey position:
And then move transmission around and see how things fit:
With this setup, I get:
engine moved rearward: 4 1/2"
engine lowered: 4 1/8"
ground clearance to engine oil pan: 7 1/2"
ground clearance to flexplate: 7 3/8"
ground clearance to transmission pan: 7 5/8"
So I've lost a bit of ground clearance:
But it sure seems like a good fit, and will help with my concern about the forward mounted rack.
from
bluesmobiles.proboards.com/index.cgi?action=gotopost&board=owners&thread=616&post=3544
and it struck me how close the rear of the block was to the firewall. Recall this pic, showing my trans/motor simulant lowered to provide the same ground clearance as stock (with dry sump pan)
It seemed to me that just lowering the motor, leaving the harmonic balancer bolt in the same fore/aft location, moved the back of the block away from the firewall, so that the transmission/engine combo could then be moved rearward.
I could move it back 5":
I read this thread about the benefits of engine setback vs. lowering:
www.camaros.net/forums/showthread.php?t=34317
and there were interesting items such as:
> Smokey Yunick always maintained that it was far better to LOWER the
> engine vs moving it to the rear. Accomplished the same thing, just
> better for the amount of work you did.
and
> I moved the engine back about 2 inches in my circle track car to gain
> rear weight. Once I was on the scales after it was done. It was only
> worth about 1/10th of a percent and a few pounds.
and
> I've heard that moving the battery to the trunk is equivalent to moving
> the engine back 8"
I'm not moving the battery to the trunk, so I don't care much about front/rear weight balance.
I suppose that moving it back would result in the car having a lower polar moment of inertia, which would result in quicker cornering ability
> ...you want to keep the car's polar moment of inertia low for quicker
> transitional handling. To visualize polar moment of inertia, imagine trying
> to twist a set of dumbbells back and forth from the handle. Sort of
> tough, right? Now imagine trying to twist the same weight in your hand
> if it was a compact sphere. This is much easier. A car, with its mass
> located closer to its center, will respond to steering input faster.
www.turbomagazine.com/tech/0806_turp_hows_and_whys_of_battery_relocation/viewall.html
Which seems a nice benefit. But one immediate benefit to my application is that moving the engine rearward 5" would result in me being able to move the steering rack back 5", which would mean that it wouldn't be so far forward of the front wheel centerline.
Here's a pic to show what I'm talking about:
Notice how the rack is forward of the centerline. I read in "The Sports Car & Kit Car suspension & brakes high-performance manual", page 29, that moving the rack forward like this "although not ideal...not as bad as it might appear...this particular aspect of rack positioning isn't overly critical, except perhaps at the extremes of lock".
from
books.google.com/books?id=smKpTCICw8QC&pg=PT29&lpg=PT29&dq=his+particular+aspect+of+rack+positioning+isn%27t+overly+critical&source=bl&ots=BBBSadWfTJ&sig=F5AM48lRbPgYhCbyvHuFX_4dsyo&hl=en&sa=X&ei=tRFhT5imC-rY0QHW5qzSBw&ved=0CCAQ6AEwAA#v=onepage&q=his%20particular%20aspect%20of%20rack%20positioning%20isn%27t%20overly%20critical&f=false
But still, it seems that moving the engine rearward, if it wasn't difficult, would provide gains all around.
The back of the passenger valve cover is about even with the back of the block:
while the driver side head is about 1" forward of the back of the block:
This maps nicely to the firewall, as the firewall curves forward by the driver head.
Fore/aft is limited by the firewall on the passenger side (because it has the huge a/c box behind it). If I have 3/4" of clearance between the passenger head and the firewall, the driver head will hit the firewall a bit, but there's nothing inside the car that would be impacted by just notching the firewall and moving it inside a bit.
Inside, up/down is limited by "globey". This guy:
that mounts under the giant a/c box. Here's how it looked in the Fury originally:
the trans tunnel rammed right up to it:
Here's a test-fit with the a/c box without globey:
and with globey:
It looks like globey doesn't really impact trans positioning much. I opened the a/c box, and it looks like if the trans hit the a/c box, I could notch the box if necessary, as it's just open air at that place:
and I could notch globey if necessary, so the limiting factor seemed the front forward bottom edge of globey. Keep the front face of globey correct.
Step 1: Mark this position with the trans jack/scissor jack combo:
step 2: remove globey and a/c box:
then add in replacement wood form that mounts to a/c box holes in firewall:
add in form that bolts to seat location:
then rest the third piece on top that shows the globey position:
And then move transmission around and see how things fit:
With this setup, I get:
engine moved rearward: 4 1/2"
engine lowered: 4 1/8"
ground clearance to engine oil pan: 7 1/2"
ground clearance to flexplate: 7 3/8"
ground clearance to transmission pan: 7 5/8"
So I've lost a bit of ground clearance:
But it sure seems like a good fit, and will help with my concern about the forward mounted rack.