Engine Cover on G Turbo

[Roger 912 31]

I am curious to find out whether the engine cover is necessary on the G Turbo or not.

My red one does not have but the green one does.

Does the engine cover restrict air flow and therefore reduce the cooling of the inlet/plenum or was it fitted to reduce noise in the cockpit.

Not having the engine cover would assist in fire control with an extinguisher as there would be one less cover to remove.

On the aesthetics side, I prefer it without as the inside of my engine bay, which is spotless, can be seen from the outside.

Any comments please.

[mike.griese 0]

The engine cover and rear hatch, along with the lower NACA ducts in the sills helps move air through the engine compartment. The small lip a the top of the louvers on the rear hatch helps create a negative pressure area above the louvers. The seal between the engine cover and the rear hatch helps pull air out of the engine compartment into that negative pressure area. The air comes from the ducts on the sill.

If you have a carbureted car, the engine cover may have a fan in it to help keep the fuel in the carbs from boilling off from the heat of the turbo when the car is turned off (at least in the US - not sure about the rest of the world). There is also a duct from the left hand side scoop to the turbo to help keep it cool, since those cars don't have water cooled turbos.

Is the engine cover necessary? I suppose it depends on how you drive and what the ambient conditions are. If you aren't into the turbo much and don't have a lot of hot days, probably not. On the other hand, if you carry anything in the boot that is sensitive to temperature, you might want to keep it installed, no matter how you drive.

[Buddsy 1,641]

The small lip a the top of the louvers on the rear hatch helps create a negative pressure area above the louvers

I thought that was added to cancel the effect of the rear spoiler that Colin Chapman didnt like which was added by Guigaro? Not sure if thats fact or legend!!lol

If you have a carbureted car, the engine cover may have a fan in it to help keep the fuel in the carbs from boilling off from the heat of the turbo when the car is turned off (at least in the US - not sure about the rest of the world). There is also a duct from the left hand side scoop to the turbo to help keep it cool, since those cars don't have water cooled turbos.

I thought that lip was added to cancel the effect of the rear spoiler that Colin Chapman didnt like which was added by Guigaro? Not sure if thats fact or legend!!lol

Mine doesnt have the fan and I think the left side scoop didnt have an air duct until the later HC G cars.

Buddsy

[mike.griese 0]

My Federal '83 Turbo has the left hand ducting and fan. That may be a North America thing. The engine cover is also lined with foil to provide some heat insulation.

If nothing else, it will keep your boot a little cleaner as it will keep road grime confined to the engine compartment.

[Buddsy 1,641]

Mine has the tin foil on to. I like it with the cover, does give you more boot space. I think the engine looks nice and snug in the compartment. But I can see why you would want the engine on show, it is a nice looking lump!

Buddsy

[jimmybondi 4]

Why not use the best of both worlds, a transparent cover:

Frame made of aluminium profiles, cover is made of 6mm Lexan

Could also be illuminated:

Edited July 24, 2009 by jimmybondi

[b041ac1 0]

Done the same, as you say, best of both worlds.

[Roger 912 31]

I would have expected the louvres on the back to create a vacuum sucking air away from the engine out through the louvres which would also suck up all road spray from below. It would be interesting to find out if the fan fitted to the US cars was sucking or blowing.

I just get a feeling that my red one that runs without the cover over the engine runs a lot cooler than the green one that has it.

What I think I will do is fit a remote temperature gauge in the same spot in both cars and see what the difference is.

I have thought about a plexiglass cover, but it looks so good without any.

My plenum and casting from the turbo is in black crackle and that looks so much cooler, in both uses of the word, than the red colour plenum (which I have in the green car)

Edited July 25, 2009 by Roger 912

[Buddsy 1,641]

Hi Roger

Good idea with the temp sensor to see if there is any diference. There was a discussion about the engine bay vacuum effect before. I think it was with a owner who wanted to replace the louvres with a S3 glass rear hatch. The talk was of vacuums and low pressures and sucking hot air out of the engine bay. This would seem logical but some other owners said but in rain, light drizzle or fog etc you just dont the air moving like this. Something like that any way!!

I like the black too, I think people like the orange as it was used on the later HC engines and on. I have also noticed that there are more cooling fins on the older black plenum tube than on the orange HC one. I wondered if this had any effect on charge cooling and ultimatly engine detonation?

Buddsy

[thom_77 1]

I would have expected the louvres on the back to create a vacuum sucking air away from the engine out through the louvres which would also suck up all road spray from below. It would be interesting to find out if the fan fitted to the US cars was sucking or blowing.

I just get a feeling that my red one that runs without the cover over the engine runs a lot cooler than the green one that has it.

What I think I will do is fit a remote temperature gauge in the same spot in both cars and see what the difference is.

I have thought about a plexiglass cover, but it looks so good without any.

My plenum and casting from the turbo is in black crackle and that looks so much cooler, in both uses of the word, than the red colour plenum (which I have in the green car)

The fan on the engine cover on my car sucks in cool air, as opposed to blowing out hot air. It really does make a difference; its a pretty powerful little fan and you can definitely see the temp needle go down when its engaged usually.

The PO had the fans hooked up to manual toggle switches also as opposed to relying on the sensors, which the dealer I purchased it from said could be too unreliable. I think its a good system like that actually, as long as you remember to turn them off after shut down.

Its funny, I never realized that the aerodynamics of the louvers were so specifically designed to move air through the engine compartment, but I suppose it all makes sense. I wouldn't remove the louvers unless other provisions were made for getting extra air into the engine bay.

[Buddsy 1,641]

Hi Tom

I know you said a PO added the manual switch but do you think the fan was a factory fit orig?

Just curios to the differences.

Buddsy

[silverfrost 1,390]

Done the same, as you say, best of both worlds.

Very tidy install Tony looks very eye catching and well made.

Regards Danny p.s bet its a bugger though to keep cleaning the underside of the perspex had the same problem when i had clear louves and no engine lid,

[thom_77 1]

Hi Tom

I know you said a PO added the manual switch but do you think the fan was a factory fit orig?

Just curios to the differences.

Buddsy

Yeah, I'm almost 100% sure the fan is original. The dealer said that the only real modification the PO made was to connect it to the manual toggle switches. She's in the shop right now, but if you're interested I'll snap a couple of pics when I get her back (this week hopefully) so you can see the setup.

[Buddsy 1,641]

Pics are always good!

Buddsy

[Roger 912 31]

Took a drive today and I have a slight oil leak from the cam cover on to the exhaust manifold.

I noticed that when the exhaust was hot enough to burn the oil off, the smoke comes out of the louvres, proving to me that the louvres cause a vacuum behind them that sucks cool air from right down at the exhaust manifold level past the engine and plenum up to the louvres where it is vented.

I think that the fan fitted to the US market was to try and cool the plenum chamber perhaps to get a cleaner fed spec? Rather use cold air from the back for cooling than hot air coming up from the exhaust and turbo.

Just my thoughts.

[Choppa 214]

I ran my S3 with the engine cover removed for a while. One day while the wife and I we were enjoying a drive in the country we stopped at a pub for a meal As we walked across the car park a heavy shower of rain/hail started and the rear window just shattered into pieces and fell into the engine compartment. It took ages to get all the bits of rear screen from the nooks and cranies in the engine compartment and around the engine, there are probably still a few bits in there somewhere. I've always kept the engine cover on since then.

[Buddsy 1,641]

arh but what if the palstic cover then smashed you would have bits of plastic to deal with too!!! lol

Seriously your encounter is a valid point I had never thought about but I dont supose its much of an issue with a turbo and its louvres?

Buddsy

[Choppa 214]

Yes, with the louvres on the turbo you won't get any problems with breaking rear windscreens , but I'm a bit worried for the chap you mentioned who was thinking about fitting an S3 tailgate to his turbo

[AJay 1]

I used to run my 84 turbo on a daily basis without an engine cover, when it rained no 4 and 3 spark plug holes filled with water and i would get a horrible miss fire until it all dried out 40 miles plus. it was a night mare.

[Roger 912 31]

Andy. I take it that you kept the louvres in place but just removed the engine top cover.

I am surprised as the louvre panel has exactly the same hole over the rear of the engine and turbo as the engine cover. I wonder how the rain got in so bad.

I did have a problem when the garage washed the car and put a pressure wash through the louvres. Car would not start until we dried out the plug recesses.

I have run my red one without the engine cover for nearly 2 years and never had a problem with rain, but I guess we are talking about your English weather and not South African. We have been in a drought for nearly a year now.

Edited August 6, 2009 by Roger 912

[jimmybondi 4]

I used to run my 84 turbo on a daily basis without an engine cover, when it rained no 4 and 3 spark plug holes filled with water and i would get a horrible miss fire until it all dried out 40 miles plus. it was a night mare.

Same here, I can confirm that. Really embarrassing sometimes...

[AJay 1]

Andy. I take it that you kept the louvres in place but just removed the engine top cover.

I am surprised as the louvre panel has exactly the same hole over the rear of the engine and turbo as the engine cover. I wonder how the rain got in so bad.

yes i kept the louvers in place... it was just the engine cover.

Uk spec cars have a blanking plate over the plugs on the engine cover. as you can see from below, its by the chargecooler, this stops the rain dripping on the plugs. It only happened if the car was parked facing down hill, but it didn't need to be very much of a hill!

[hepkat63 11]

On 6/8/2009 at 07:57, AJay said:

yes i kept the louvers in place... it was just the engine cover.

 

Uk spec cars have a blanking plate over the plugs on the engine cover. as you can see from below, its by the chargecooler, this stops the rain dripping on the plugs. It only happened if the car was parked facing down hill, but it didn't need to be very much of a hill!

 

Can you still buy these blanking plates?  Look like a great idea !