16 replies to this topic

[Aerodynamic]

I am not happy with my rear end grip and wants to improve this as I think  it is a bit to oversteer to my liking.

I know it can be compensated by removing grip from the front end

but I prefer if possible to increase grip in my rear end and is now thinking about lowering my engine.

My Honda K engine is a bit taller then the Opel engine, but I never  really pushed the car with my Opel engine.

 

Currently my oilpan is sitting somwehere 10-15mm above my underpanel reference plane and  I am both thinking of make changes to oilpump

and oilpan and guessing I could gain around 20mm here  and then I also thought about lowering down my oilpan to the same level as underside of underpanel and therefor I should be able to lower my engine somewhere around 30 mm.

 

So 2 questions comming up. Lowering the engine will help I am sure but will it be noticable when lowering it 30mm?

 

Cutting in my underanel I´m thinking around 10mm gap around the oilpan. Will it change the aerodynamics? If I make the oilpan complete flat

and compensate by removing one of the NACA duct, Its not completely flat here anyway because of the service panelunder the oilpan.

 

 

Any thoughts?

 

Br, Per

[Tony H]

Don't think there would be any aero problems but your driveshafts might be at bad angles.

[Arno]

but your driveshafts might be at bad angles.

 

This is usually the problem with lowering a transverse engine/gearbox combo without going to a custom gearbox housing.

 

The axle height on the wheel end remains the same so as you lower the engine and thus the gearbox/diff too you start to angle the driveshafts more and more.

 

In itself this will work, but it will put more fricttion and heat load on the CV joints and as a result they can become more of a 'consumable' than you are used to.

 

Sometimes you can compensate for this by not moving the engine vertically down, but by tilting/angling it around the driveshaft axles so the block still sits lower in the car but the driveshafts stay at the same location.

 

Needs consideration as to oiling and oil return flows in the engine if the tilt gets big enough though.

 

First thing to check would be to see what your driveshaft angles are at ride height and if lowering the engine would still keep them OK.

 

Having said that.. I have a Honda in my S2 Elise and the bottom of the engine sump is pretty much completely at the same level as the undertray (with a few little neoprene foam strips to stop it ratting..), so there's a good chance you can lower the engine at least to on or close to the undertray on the VX too.

 

Don't think you'll notice much from a CoG standpoint though, but that's my guess...

 

Bye, Arno.

[Aerodynamic]

I thought abut the drive shafts too. But what is an OK angle? An idé is to tilt it slightly, droppen the engine 30mm in the front and 15-20 in the rear. But the total weight move with be tiny and like you say is even 30mm noticeable?

[fezzasus]

Why will lowering the engine change the bias of front to rear grip? the distance, and therefore weight distribution, to front and rear wheels won't change.

[Aerodynamic]

Because I will reduces roll over rear axel where the engine sits. There for increase grip over rear relative front axel.

[fezzasus]

Because I will reduces roll over rear axel where the engine sits. There for increase grip over rear relative front axel.

 

I see.

 

Wouldn't stiffer suspension be easier to fit?

[Aerodynamic]

True but why isnt very stiff SUVs fast then?

Because I will reduces roll over rear axel where the engine sits. There for increase grip over rear relative front axel.

  I see.   Wouldn't stiffer suspension be easier to fit?

[Duncan VXR]

Angle of the engine differs somewhat engine to engine. A few degrees is normally fine but something to check on what the honda setup likes and dislikes.....sure I read they are a bit sensitive to oil levels? Its all a compromise and def look at driveshaft option 1st....no real negative to sitting a chunk lower 😊 As mentioned funky angles on the shafts will consume them even with fancy high temp grease DG

[Aerodynamic]

I want to keep my car as road car, to be able to go and buy icecream with my son and take some roadtrips maybe.

I´m also thinking of buying new rear hubs with adjusted center but these are very expensive and where lowering the Engine

isn´t anything costly but maybe a bit time consuming.

Im also thinking of changing to harder springs from current 425/550 to 500/600 and I already have a 1" roll bar.

 

About oil level, I have some oil traps in current oilpan and if I  mayke a new oil pan that is 20mm lowered I´m thinking of compensate the volume I loose with some etra sapece forward or rearward.

 

Is anyone have any exprience from any car when the Engine is lower or a big lowering of weight has been done?

 

Br, Per

 

 

[Madmitch]

I would doubt you will notice any difference on the road and probably not on the track either!  A lot of money and work and a possibility of other problems as suggested above.  Why not just increase the front anti roll bar stiffness a tiny bit, that will neutralise the rear end and potentially make it fractionally quicker around corners although harder to drive on the limit. 

[Mattyboi]

Show me a none F1 driver who can tell the difference in 20mm engine height and i'll show you a liar. It would be worth doing the calcs to check the difference in CofG etc before bothering to do this. Sent from my iPhone using Tapatalk

Edited by Mattyboi, 28 August 2016 - 08:00 PM.

[Madmitch]

Just thinking about it, the static roll centre would be unchanged so lowering the CofG would only reduce the amount of roll at any given speed, and not by much.  It wouldn't affect the front/rear balance I think, so back to a stiffer front anti roll bar.

[Aerodynamic]

It wouldnt maybe change the front rear balance that much but it should help the rear more then the front. And like you said it will lower the rear and overall centré of gravity and not static roll center which is the point. I was hoping that some race guy in here had tested this in reality. I have a book here at home to calculate this kind of stuff but its not easy to find time for this right now, taking care of house and family. Yesterday I checked the drive shafts and if you lök from the rear they are pointing more or less straight out, while if you look from above they are point ing back wars, by how much is hard to tell. But if they point back wars with 2cm it should be safe lowering the engine in rear by 20mm.

Just thinking about it, the static roll centre would be unchanged so lowering the CofG would only reduce the amount of roll at any given speed, and not by much.  It wouldn't affect the front/rear balance I think, so back to a stiffer front anti roll bar.

Edited by Aerodynamic, 29 August 2016 - 06:55 PM.

[Mattyboi]

Calculating it first will be much quicker than doing it for real to find out it wont make any difference. The calculations shouldnt take long, put them in a spreadsheet so you can change the height figures etc and can see the changes.

Edited by Mattyboi, 29 August 2016 - 07:34 PM.

[909]

I am a bit puzzled by your logic.

 

Sure, lowering the engine will lower the CG, but lowering the engine by 20mm, I don't believe, is enough to make any noticable difference.

 

This difference will also affect the front grip as much as the rear.  The chassis does not twist to any great degree on these cars.

 

To achieve the grip you want in the rear requires a re-balance of the front to rear grip.  That can be achieved by a number of different ways.  e.g. camber, tyre pressures, tyre size, damper settings, spring rates, roll bar stiffness, front to rear road height, etc.  Changing any one of these will no doubt change some other parameter, but that's the compromise that has to be accepted.

[Aerodynamic]

I am about to finish this idea soon. Most of the engine mount are fixed and modified oilpan soon ready. Oilpump is ready too. Will be lowered around 17mm rear and 27mm front