Lowering or moving the Q engine back?

[dgoodno]

What would result from lowering the engine one or two inches? Or moving it back? I have the engine, transmission and all out and have been told that adjustments can be made without too many problems.

But the handling is great already! Do I really want to screw with this? It's been a couple years since I had an accurate weight per wheel and I don't remember what the individual readings were, just that the total is down to 3,800 pounds.

Remember, this is strictly a track car where handling on corners is of great importance.

[diamondj30]

thats a good trick alot of jeep racers do.they go back and down.that would be something else.id start by whieghing the front and back to see how much wheight you have to transfer.being a track car i would do it if necesseryi take it the roll cage is in already.thats inportant.heavy..if you think you can get more out of it,being you said it already handles great,and i asume familiar to you.its your call.

[dgoodno]

I'm already anticipating a different car handling wise. I'm going to have more power and anticipating going with AZ's rear buy, that will add even more change.

[Rex]

Did you see this post http://www.nissaninfiniticlub....53929 about the impact of letting the rear sit a little lower. I'd think you could say that shifting the the motor weight back, even if just "somewhat" more behind the front wheels would help diminish "nose dive" entering corners.

<keep in mind, I have NO idea what I'm talking about >

[dgoodno]

RexYou must be kidding. :pface You're brilliant!! The act of lowering the car has three effects; it lowers the center of gravity, it reduces lift, and to some extent it reduces resistance.

Lowering the center of gravity has the most effect, certainly for this application where stability on the corner is not helped much by the other two.

In some respects this appears to be better then lowering the car. With 18" wheels and the downward pressure turning at the bottom of a run, there is little wheel-well clearance.

But is there a downside?

[Rex]

What I meant was I only "think" this would be the effect. I have no real world experience with this.

I hate to bring up NASCAR, but at some tracks teams would run what is called a "drop-snout". Now with the rules, they couldn't make the front of the car any lower, but they'd mount the engine lower in the frame and that would help with "turn-in". The only consequence I can think of is decreased clearance. I don't see you bottomng out, but would it effect the airflow (cooling) and how would you accomodate the different angle the driveshaft would have where it attaches to the rearend?

[dgoodno]

I already have terrible cooling problems so almost feel it can't get any worse.

As for how, I will leave that to Tony my mechanic. He says he can do it!

What about moving an engine back? That will shift weight rearward. At what point will this hurt, and in what way?

[Nismo_Freak]

I already have terrible cooling problems so almost feel it can't get any worse.

As for how, I will leave that to Tony my mechanic. He says he can do it!

What about moving an engine back? That will shift weight rearward. At what point will this hurt, and in what way?

Your main problems will be the driveshaft angles resulting. If you move the engine back an inch you need to shorten something by an inch. You then need to remeasure the angle of the driveshaft, and as a result you may need to shim the engine in order to give you an acceptable angle.

From my experiance you want to move the engine as far back as possible, and as low as possible. Thats one reasons why FC's and FD's have smooth turn-in's and good handling, because of their low center of gravity the rotary engine gives.

[dgoodno]

Except for "getting it right" there doesn't sound like a downside?

[cweberj30t]

What engine/drivetrain are you running? I would be most concerned with the driveshaft. If you would lower the engine/transmission and move it back, the angle on the driveshaft would be comprimised. Other than that, you would have a lower center of gravity and less roll. I'm assuming you're planning a custom made drive shaft.

[dgoodno]

I'm running stock. The engine is being overhauled right now, and the transmission was just rebuilt (Not a level 10). So the car is in pieces right now.

Can anyone speak to moving the engine back. At what point does it induce oversteer? Is equal weight on each axle really desireable, or do manufactures have more weight up front for a reason?

I remember on my Porche 924 with transaxle, it was balanced more then most. It would spin on ice on the slightest mistake.

[Jeff Williams]

I say go for it.

Moving the weight does change everyting about the way your car will handle.

It will help, when diving into a corner, a lot less force will be on the front tires.

I would think that most of the change will be felt at the apex of the corner, and exsiting the corner, where rear traction is most important.

I think the change will be for the better.

With the lower gear, and a strong engine/transmission, the extra weight on the rear will help keep the wheelspin to a minimum.

If I were you, I would try to retrofit the struts with some kind of coil-over assembly, with adjustable ride height. Then you could transfer the weight at will.

A dry sump would really help the clearance issue, of the oil pan.

Many people talk about "Perfect 50/50 weight balance". But, the rear engine cars, are biased to the rear, and the front eninge cars are biased to the front. I think it is more of a cost issue, than a balance issue.

We tried for a 55/45 front to rear weight ratio, on the oval tracks, with a 55/45 left to right ratio. Then we used different spring rates, sway bars, and mvoed the frame height, to best fit the particular track.

In road racing, you turn left AND rignt. We balanced the car left to right, but kept the 55/45 front to rear. I don't really know why, except that is the way Bobby Allison did it, so we did it too.

But we were dealing with a solid rear axle, not IRS.

[dgoodno]

Thanks Jeff!!!