Fox / SN95 SBF engine setback

[tulowd]

Hey All:

As some of you know, my '87 vert continues along its way towards pretending to be a road race / well handling "sports/muscle" car. While this is an unlikely goal to ever be met, one of the motivations is to continue improving the metrics of the car from what Ford originally did. Seam welded chassis, full frame, 8 pt roll bar, coil overs, Koni double adj sport shocks, full poly/delrin/spherical suspension mounting arrangement, Torsen diff, Cobra brakes, relocated battery.....all the usual small stuff has been done.

Weight reduction efforts will also continue, once the interior and sound system are done; PSP ported alum Victor Jr heads will shave app 50 lbs off the nose in the spring.

Maximum Motorsport Tubular k member and front control arms are in the future as well; which brings us to the point of this thread:

Planning on moving the engine back 1" as allowed by the K member design. It appears only the driveshaft length and collector to catalytic converter pipes will need to be shortened by 1". The trans cross member looks like it will work, clearance between scattershield and firewall looks ok; have BBK 1.75 long tubes going on with the new heads, along with another MM long clutch cable and heat shield.

Has anyone done this, and what comments and insight can you give me? Interested in the improved weight distribution and resulting steering effort reduction and increased front tire bite/ reduced understeer. Will eventually increase the wheelbase by 1.5", as well as widen the front track with Cobra length control arms. I'm of the mind every little bit helps.

Have at er - all comments and thoughts appreciated.

[ZR]

My $1.98. Not sure the end justfies the means. The MM K member and additional wheel base option does work. Before I went to the hassle of moving the engine back, would pop for an SLA and 10" front rims and call it a day.

[tulowd]

part of my longer plan is to do 10" front wheels after the wheelbase extension and track widening.
I'm thinking moving engine back is not that expensive; maybe a couple of hundred bucks.
SLA would likely work even better with less mass on the nose as well - after the lottery win.

Question is: has someone done an engine setback in a Fox and what does the car feel like after - any discernible difference and any real minuses?

[2DXTRM]

Why the BBK 1 3/4 over the Kooks??

Some things to consider with the engine setback. Taking the bell housing out can be a pain in the arse. Front sump of the oil pan may hit the rack (depending on what brand oil pan you have). Shortening the driveshaft, possibility of headers hitting the firewall etc.

[TurboFox]

My engine is set back basically against the firewall. I am going to have a real blast trying to get the bellhousing bolts out to remove engine. Will likely have to pull it all at once

[Ponyryd]

For trans removal it would be as easy as dropping the k-member a few inches to get to the bellhousing-nothing to worry about IMO. I've never done it but my main areas of concern would be the oil pan contacting the rack and clearance between the header tubes and steering shaft-1" will probably mean you need one custom bent tube at the very least. 1" may be just enough that you can get away without modding the driveshaft, would need a test fit and good hard run to know for sure.

[tulowd]

Thx guys. The oil pan and trans cross member will work as is. Not concerned about the bellhousing removal - trans can come out as is, to get at clutch motor comes out.

Headers not sure until they go on, steering shaft was lengthened and moved to accommodate the Kooks which still needed a custom #8 tube. Swapping to BBK to make more torque, gain some ground clearance and clean up the slip on leaks. Kooks will be for sale in spring; they are 1-7/8 ceramic plated with ported head adaptor plates. Would be ideal for a 351 based 408 or 427 stroker methinks.

Concerned about the gains - some of the more techy forum posters are saying 1" setback makes less difference in weight bias than relocating battery. I get the moment of inertia on a 40 lb battery 10" in front of the wheel base, but a motor/trans rear shift by 1" should equal more than removing 27 lbs off the front wheels. That is equivalent to swapping one cyl head from iron to alum. or losing efi and a/c system.

Any engineering types on here feel like using their pocket protector and slide rule to figure out the potential weight bias improvement ?
Looks like the complete motor with alum heads, front serpentine/alt, headers, carb, fluids, flywheel, clutch and scattershield should weigh 500 lbs; trans is app 75 lbs. Current scale weights incl me (175 lbs fully dressed) in drivers seat, full fuel tank and 110 lbs of ballast in trunk. 52.6% F 47.4% R

With 50 lbs ballast (=stereo install), and new cyl heads (-50 lbs) it looks like it will be app: 52.7%F 47.3%R at 3640 ttl weight.
K member and A arms will knock another 35 lbs off the front. Lightweight wheels will save another 40 lbs, equally distributed.
Looking for alum rear bumper crash bar from 79 Pace car.

Engine relocation should turn that into......WHAT? Bueller......Bueller, are you on it? lol

[RedSN]

Any engineering types on here feel like using their pocket protector and slide rule to figure out the potential weight bias improvement ?

Missing some information for that calc: what is the wheel base, and what is the current location of the center of mass of the engine/transmission?

Assuming a wheelbase of 100 1/2", and locating the engine/trans at say 9" behind the front wheels?
Moving a 575 lbs mass 1" closer to the rear will result in:

-6 lbs off the front
+6 lbs added to the rear.


....so the techy forum guys are right.

[jibbijib]

What about moving the k member forward an inch? Youd have to change your fenders and bumper extensions to 90 plus, but you'd gain caster which apparently helps these things turn better.

Has it been done before? Is it maybe too complicated? All I can think of is youd have to re-box your front frame rails, punch new holes for the k member mounts, adjust the motor mount position and change your oil pan. Unless you have a dry sump, which would be ideal anyway.

Thoughts?

[tulowd]

Will eventually be extending the wheelbase by 1.5" forward via MM k member + forward offset control arms. Never heard of moving k member forward - lots of extra work like steering shaft challenge as well.