how much will a 2" engine setback affect weight balance? - Team Camaro Tech
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post #1 of 12 (permalink) Old Oct 8th, 04, 02:02 PM Thread Starter
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i got to thinking the other day- when i get around to doing the LT1 swap in the Nova (hopefully) this winter, how much benefit would one get from shoving the engine back tighter against the firewall, since there is no distributor back there to get in the way? i think 2" is pretty easily doable- and i have even thought thru the crossmember and clutch linkage mods to make everything work, along with the shorter driveshaft, of course.
also, since i'm moving weight around, the battery will go in the right rear corner of the trunk and a fiberglass cowl hood might got purchased, as well.
would it be worth the effort- which should be about a good afternoon of fabricating?
the thing that got me thinking about this is my eventual dream of a pair of turbos hanging off the front of the engine, and the extra mass they will add to the car.

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post #2 of 12 (permalink) Old Oct 8th, 04, 02:06 PM
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I've heard that moving the battery to the trunk is equivalent to moving the engine back 8"

Have never done the math myself, but it sounds very plausible since you are moving a 50# battery about 12 feet . . .

I personally wouldn't bother moving the engine only two inches. More trouble than its worth IMO unless you are building an all out competition tyoe ride.

That's just my opinion though

E85 racer and E85 carb builder

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post #3 of 12 (permalink) Old Oct 8th, 04, 04:49 PM
 
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Eric,

A SB when pushed tight against the firewall should move about 2", but I bet he will have to ding heck out of his firewall to make room for the distributor..

Put frontward extended 2" "stirrups" for rigid motor mounts and a flat plate backwards at the tranny mount and shorten the driveshaft 2" and he is home free if he is running an auto tranny..

Otherwise the Z-bar mount will need to be moved 2" at the block and the tranny levers will need to be delt with..

I think guy's have always done this whenever they mounted V-8's on the old 6-banger mounts years ago before there were store-bought stuff to use like nowaday's.. But maybe not to this extreme??

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post #4 of 12 (permalink) Old Oct 8th, 04, 07:51 PM Thread Starter
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it's an iron head 94 Caprice LT1 going in there- no distributor in the way, since it is mounted up front under the water pump. i can move the clutch linkage mount on the frame back the same as the engine, and make a shorter linkage from the pedal to the Z-bar using round tube and sperical rod ends. the headers will clear fine. thinking maybe use a TH400 crossmember and move the mount over using the trusty mig welder. the shifter hole in the floor is already kind of hacked out anyways, so what's a little bit more hacking? besides, i have a welder i can use to patch the hole back up, anyways.
the frame stands can be moved back on the engine crossmember one hole- which looks to be almost 2"- and i can weld some extensions off the back of the crossmember to bolt the stock frame stands down like stock. part of the appeal of doing it this way is that to the casual observer, it will look stock- and someone who knows what everything is "supposed" to look like will get the feeling that something isn't quite kosher as they look at it, but won't get it right away.
i know i can move it back pretty easily, just wondering about the weight balance benefits.
perhaps this should be in the suspension forum- which is where i thought i put it originally. it's been a long day...

you don't plan sincerity.
you have to make it up on the spot.

wanna hear about 20 years ago when i was too smart to know any better?
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post #5 of 12 (permalink) Old Oct 10th, 04, 05:35 AM
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If you move the engine back 2", the shift in the center of gravity will be less than 2".

If you really want to change the center of gravity, consider fiberglass fenders and hood.

Dave
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68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
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post #6 of 12 (permalink) Old Oct 11th, 04, 08:46 AM
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If you do it, hopefully you will post it as it progresses! This really sounds like an interesting project to me. Will you still have room enough to do plugs or pull a head? Are you planning electric fans for cooling?
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post #7 of 12 (permalink) Old Oct 12th, 04, 07:47 AM
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novaderrik,

i researched this awhile back. i was shown through diagrams and a good deal of math that the engine/trans would have to be moved back approximately 12-15 inches(depending on weights involved) to equal the balance benefits of moving the battery to the trunk. the cg of the engine/trans is relatively low compared to the battery and hood.
so 2 inches wouldn't have a large effect, but everything adds up and it cant hurt F/R balance.
an extra 2 inches for turbos would be nice !

i decided not to move mine back because i have a rear HEI that i already relieved the firewall for, so i dont have any room to go back.
if i had an LT1 i would be tempted to do it.
maybe try a search on corner carvers....
just my opinion, good luck with it....

kip
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post #8 of 12 (permalink) Old Oct 13th, 04, 06:58 AM
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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. He was almost always correct and was always YEARS ahead of others in design and theory. I took his advice many years ago, as we were running dirt track stock cars, with rules that stated (as they still do in most racing classes) "no more than 2" engine set-back. But they didn't say anything(and most still don't) about LOWERING the engine! Did it, won the track championship that year, didn't cost us any money, just a few hours work. Always read and listen to what Smokey had to say.
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post #9 of 12 (permalink) Old Oct 13th, 04, 07:50 AM
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Smokey was 'The Man' when it came to common sense engineering in cars [img]graemlins/thumbsup.gif[/img]

Nova;
Are you looking to increase Weight transfer for Drag Racing or looking for cornering/overall handling of vehicle ???
Raising the CG will effect transfer of more weight to the rear during acceleration, lowering the CG will effect cornering more.
You can pretty much fiqure the Vertical CG of your car will be @ the centerline of the Camshaft in your engine/driveline confiquration (you can compute this but it takes some measurin' and jacking to get to it...). Just like 'nothingbut...' said, 'the engine position vertically will probably have more effect on your car' than trying to move it horizontal to the CG.
If you want to fiqure out the CG "horizontally" (distance behind the front wheels) for your car - divide the Overall Weight by the Rear wheels/axle Weight and multiply that by the Wheel Base (in inches) of your vehicle. The number will be the CG location in Inches from the centerline of the front axle/hub. You can then use these numbers to see how changes in component location could effect the weight transfer of the vehicle in acceleration and braking.

Hope some of this helps and doesn't make anyones head hurt;
John

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post #10 of 12 (permalink) Old Oct 13th, 04, 08:48 AM Thread Starter
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drag racing is- and probably always will be- a secondary deal for my car. it is primarily a driver- and it does get driven a lot. but it is fun going around twisty roads at somewhat "extra legal" speeds. not saying that every 30 mph corner has to be taken at 90, but there is a 20mph corner a half mile from my house that i take at around 65 on a semi regular basis if i'm not carefully watching my speed..

you don't plan sincerity.
you have to make it up on the spot.

wanna hear about 20 years ago when i was too smart to know any better?
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post #11 of 12 (permalink) Old Oct 13th, 04, 03:13 PM
 
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He, He!!

I used ta get big P/U's off my tail when I had my '87 Chevy Sprint ER, 3-banger corn-popper that weighed like 1500 pounds, dead stock!!

The little sucker would corner like a SK-8 Board!!

They would always seem like they wanted to push me until we came off the hill into the curve at the bridge at the bottom and I was running at least 75mph!! They slowed down REAL QUICK and by that time I was way out front AND in our neighborhood...

He, He!!

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post #12 of 12 (permalink) Old Oct 14th, 04, 07:27 AM
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Haven't posted on this site for a long time. 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. Not worth the effort on a street car. JMO

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