What are the pitfalls of raising my engine to stop the sump grounding?

[MarkTheGoose]

I'm considering raising my engine slightly to try to avoid quite so much grounding of the sump (I've done less than 2,000 miles and 'touched' the ground 3 times!) and I'd be interested in other's experiences and observations. Clearly raising the centre of gravity is never a good thing, but the engine really does seem too low right now.

Car is a CSR 200, used mostly for touring. It's a 2.3l Duratec dry sump engine.

My plan is to fit James B's cunning "sump guard ramp" to the car, but on starting this project, I've discovered that my sump is around 10mm lower in the chassis than James's was.

James's device looks like this:

What I've done so far is check the ride height, tyre pressures, suspension settings, etc. The car is currently 147mm ride height at the front, without me in it and the CSR factory spec calls for 140mm-145mm. The car drops ~2mm at the front with me in it. Also without me in it, the lowest point of the sump is 73mm off the ground:

I've checked the clearance between the bonnet and the cam cover and it seems at the closest point that I have around 12mm of space:

I've checked the engine mounts and they both seem to be OK, the rubber hasn't collapsed or anything allowing the engine to drop. I've also experimented with the implications of changing the angle of the flywheel relative to the diff with this Heath Robinson device:

and satisfied myself that changing the angle of the engine very slightly isn't going to put silly loads on the propshaft. I also checked the path of the steering column through the engine compartment and I won't run into issues with exhaust headers, etc.

My current thinking is to raise the engine around 6mm at the front, by putting washers above the rubber supports in the front engine mounts, which will bring the sump to around 80mm off the ground, but still leave 6mm of clearance under the bonnet at the closest point.

Am I missing anything, or about to do something really stupid?

[David Brown]

Have you not got adjustable platforms? Would it not be easier to raise the car 6mm all round?

[MarkTheGoose]

David - I have and I could, but the car is already at the very limit of the Caterham specification for ride height and whilst raising the engine would raise the centre of gravity slightly, raising the whole car would have a much bigger impact on all things handling. This is all me being too fussy probably, after all the car has done 20,000 miles with the engine at it's current height, including going all the way to Greece on some very bumpy roads!

[7 wonders of the world]

The correct but more involved and expensive solution is to increase the clearance underneath .... a Raceline DS give you 35mm more clearance on the leading edge.

If you do raise the engine you may also have to trim the side skin for the primaries and realign the exhaust.

All you checking and adjustments should be carried out with ballast on board too

 

 

[David Brown]

Adjusting the suspension is easy to do and take for a drive. Raising the height of the engine is also deviating from the standard settings with unknown result after a lot of work. I'm pretty sure you couldn't notice the handling difference if you raise the car 6mm all round. Tempting fate but I've never bottomed the sump (which has 80mm clearance unladen) but I do catch the chassis hoop that sits under the bellhousing on early models when crossing some speed humps. 

[TomB]

Going slightly larger profile tyre helps to - 55 to 60 profile or example. 

[David Brown]

Tom, CSR has different aspect front and rear. 50 & 40 15" ZZS so don't think that's a solution. 

[Tazio]

I am surprised you feel it's necessary to adopt a solution that clearly no-one else has up to now felt necessary, apart from set up, have you ever considered increasing the spring rates to stop the bottoming?

[SM25T]

I initially changed to 250lb front springs to help keep the car away from the road in fast depressions. Now on 300lb fronts. Smooths out the bumps too.

[David_Long]

I'm running the same engine and Cosworth sump (R400 version of it) in an S3 chassis and had a similar problem - mainly due to competition work requiring a lower suspension height.  But you can raise the engine with spacers on top of the engine mounts and also drop the gearbox mount to raise the front of the engine (it tends to tilt down at the front). The limiting factor on mine was the bonnet height but you can make a hoop to hold the nosecone higher. There was also an issue of my gearbox getting 'close' in the tunnel. Of course, changing the tilt of the engine has implications for the prop shaft and how smoothly it will run, but it's probably not great on the original design either.

[MarkTheGoose]

Thanks all for comments. 7-Wonders, I have plenty of space around where the exhausts exit the body and by the chassis bars there and whilst a Raceline sump looks amazing, I'd rather spend that sort of money elsewhere! My thinking here is that clearly CSRs are limited in numbers and they do all appear to be slightly different. Mine is number 28 and one of the early CSR200s. The reason that I'm now considering this is not to get the car miles away from 'standard' (which is less of a thing on a CSR), but actually to get it more like other CSRs. 

Bottom line - the sump hits the ground occasionally on local roads at 'normal' speeds, well below the speed limit. Both David B and James B have/had CSRs with 80mm under the sump (& little/no experience of grounding the sump), with standard ride height and springs. Mine has 73mm (well 71mm with me in it!). It also has what seems like a larger than usual gap above the engine, all of which suggests that the engine is just a bit low. My instinct is to follow David L's route and just tweak the height of the engine up a bit at the front.

[Geoff Brown]

The 'raise the engine solution' seems a tad drastic & stepping in to unknown territory for lots of reasons.

Surely it would be best to adjust the suspension to a point where the sump clearance is improved to avoid strikes but not enough to effect the cars handling which I doubt will be too noticeable.

IMO first check everything to do with the suspension to ensure all is good, tight & serviceable - bushes, rubbers, attachments, springs, dampers. A combination of all of these items being slightly tired could effect both ride height & rebound over road imperfections.

[Andrew Gilbert]

Will the approx 6mm mentioned make any real world difference to the problem?

[Mrp]

Just a thought would it not be worth just replacing the engine mounts 1st with just new standard items, I know on my S3 Sigma which was11 years old they had started to sag a bit.

Mrp

[7 wonders of the world]

Hi Mark,

I understand to reasoning with originality and cost however if your kissing the tarmac below NSL it will only take one proud cats eye or more heavily crowned road mid over take to see you sat by the roadside in a pool of oil or worse with a wrecked engine, people have suffered cracked blocks before and bonnet / side skin damage with impact.

Originality is not always the best engineering solution which is why CC now use the Raceline set up.

 

 

 

[Billy.Whizz]

Mark, why not give CC a call and ask them what might be the best option.

[Wrightpayne]

packing the right hand engine mount on a dry sumped K series, so the pump cradle clears the steering column is a known work around. I would be comfortable and see no difference in doing the same in this situation. There is a problem that needs a work around.

It is odd that your engine sits lower in the chassis compared to others. I'd want to understand why - are the mounts sagging or were there revisions/updated versions? Short term I'd pack the mounts though you will likely need longer bolts.

I also think the suspension is worth looking at - a tweek in ride height and packing the engine mounts may give desired results.

How old are the dampers / when were they last serviced? 

Ian 

 

[MarkTheGoose]

Back to basics - as now suggested by three different people (and Caterham), a new pair of engine mounts have been ordered. Mine are no doubt 16 years old. I will fit those and see if magic happens!

[Nigel Riches]

Hello from far away.

I have been reading this thread and have over the years found that all engine mount rubber bungy things are not the same. 

Some collapse and distort more than others, I now run a zetec in a 1982 chassis, and your problems are trivial against this escapade.

I have taken to using heavy penny washers under the engine mount bracket, above the rubber item, this, in your case will add another 2 - 3 mm height, and spreads the load so the bungy bit doesn't drop so much in the centre.

Have you ever read where these items were originally used? Can't wonder they aren't up to the task of carrying 100Kg +, mind you the newer cars may have better and newer mount rubbers, I don't know.

Anyway I hope you can get a fix for this problem.

Regards.

Nigel., 

 

[Blue C7]

Bit of a vague recollection but wasn't there some thing in the old blatchat about using Jaguar engine mounts or am I way off?

[Jonathan Kay]

"Bit of a vague recollection but wasn't there some thing in the old blatchat about using Jaguar engine mounts... "

Yes, including part numbers:

https://www.google.com/search?q=site:lotus7.club+jaguar+engine+mounts

Jonathan

[Blue C7]

Thanks Johnathan memory not as bad as I thought. 

[David Brown]

Sorry, it's taken me a while to get round to checking but confirmed my oil filler cap just kisses the inside of the bonnet so no chance of raising my engine. No idea if the 2.3 is slightly taller than yours but didn't think it was. 

[paul jacobs]

Well, all very interesting and some good points as well.  I've had a 260 and a 200 and ended up raising the engine on both of them by the addition of large washers.  I raised both engines so that the highest point, the cam cover badge, just kissed the bonnet, I also bent the hoop supporting the nose cone to give a little more clearance.  

It was some years ago now, so I can't remember the dimensions, but I do know that raising the ride height ruined the steering and roadholding, so went for just raising the engine.  It made no discernable difference to the ride, cornering or steering, and was easy to do and would have been easy to undo as well if I had wanted to.  I had a little difficulty with the primaries and had to enlarge the sideskin slightly, but that was all.

If the new engine mounts don't give you enough clearance, just lift the engine with some spacers, it's easy, quick and can be returned to standard if required.  I think you can overthink these things sometimes.

[MarkTheGoose]

Thanks David - my CSR200 is the same 2.3l block as yours, so should be the same height.

New engine mounts arrived and were exactly the same height as the originals!

Paul - I have you to thank for what I did next! I made up some spacers from some off-cuts from a piece of 6mm thick sheet metal, to go under the engine mounts and sourced some longer bolts. Simple job to fit - literally 15 mins. I then popped a couple of 1.5mm thick penny washers on top of each of the engine mounts, so total lift was now 9mm. Clearance between rocker and bonnet was now down to around 2mm and it was easy to deflect bonnet to touch rocker. I didn't want any scratching or banging at the top, so took one washer out on each side. Engine is now sitting 7.5mm higher than it was and I still have 3-4mm clearance between rocker and bonnet. I've been out for a couple of blats in various different road conditions and there are no funny noises from the driveline. Looking underneath, the engine looks much more like other CSR's I've looked under in terms of it's angle - it's still nose down, but not as much. The engine angle also looks much closer to the diff nose down attitude. In terms of measurements, I now have just over 80mm under the sump, compared to 73mm before and I am much happier with this arrangement. Suspension setting ride height is bang on the factory recommended. It's also now similar (sump) ground clearance to other CSRs.

So, on balance, I'm glad I've taken this approach and all I can surmise is that every Caterham is indeed made different!