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MG MGB GT V8 Factory Originals Technical - Am i on the limit ?????

Hi Gentlemen,

Got a 3.9ltr Rover V8 in a Roadster. Last year done 1K miles with the motor running on the hotter side of Normal, out today and was running very hot - just holding. The engine is tweaked - 226bhp at wheels - modified heads, edelbrock 4barrel, K&N Filter / extreme lid, lightened and balanced bottom end, RV8 manifolds, louvered bonnet, twin V8 style fans and stock V8 rad. I had a V8 3.5 stock motor in my last roadter and never had any problems with cooling. Does the 3.9 generate more heat. Persumely with modified heads and larger ports etc, there is more heat in this area.

Ian Sanders

With 226 HP at the wheels, you are generating at least 275 HP at the flywheel- more by far than most conversions, & I suspect you have well over 10:1 compression ratio, so yes, you will have a hot running engine.

With another 1500 miles on the engine, it will be truly broken in, & will run a bit cooler.

I suggest you have the headers ceramic coated to reduce the under bonnet temps, add some aluminum duct work around the radiator to ensure all the air passes through, rather than around, & get the strongest 16" puller fan you can find behind the radiator. That is what it took to cool my tweeked 4.2.

Oh yes, an oil cooler might not be a bad idea as well.
Jim Stuart

Hi, Ihave a 13 row oil cooler - only thing was when i had the restoration done, the guy put the wrong front under tray which did not have the oil cooler pipes cut outs in to allow the oil cooler to hang underneath, therefore the oil cooler is sitting behinf the grille like the hrome bumper V8's. I have very little clearance between the rad and the water pump, not sure if i would be able to mount a puller fan - am off to MG80 at Silverstone today - will have a look at what the other guys have done up there.

Ian Sanders

Oh yes forgor to say - Compression ratio is 10:1
Ian Sanders

Ian
I have almost the same spec engine as yours and have no cooling problems at all. Im running just over 10:1 comp and making 260hp at flywheel.
Ive fitted an ST spoiler, ducting the vent so that the air has to go through the rad and not round it.
Also I have fitted a heavy duty 13inch kenlowe pusher fan which also has a manual switch.
Normal running the guage points to 6.30oclock and in traffic I switch the fan on manually before the temp starts to rise and it manages to hold at about 5.30oclock.
As a matter of interest, with the Xstream filter top I have problems in the winter with the carb (edelbrock 500) iceing up. Just wondered if you have experienced the same problem.

Cheers

Mark
Mark

Mark,

I had carb icing running a 3.3, but less now running a 4.6 with xstream, however last winter I had block huggers this winter it will be RV8 style plus black Satin coating.

Ian,

I've been waiting all summer to see if temp will rise above 195 in traffic jam, using a Frontline Ali Rad and twin pacets, no vents.

Paul
Paul

Hi,

I have only just put the xtreme on and must admit, only comes out when nice and warm !!. Been back round today and managed to get quite alot of water / antifreeze in. Ran it up and appeared to run not as hot. Guage probably sits at about 5 oclock, fans will come in but very seldom cut back out unless on the move. Spoke to Clive Wheatley and he says with the spec of the motor the standard V8 rad may be on the limit. He does an uprated rad which has a condensed core, which adds about 30% more capacity, which may help. Was thinking about mounting fans which have built in surrounds on the rad rather then the standard V8 fans. Paul / Mark - did you cut the lower panel to get these fans on ?.
Ian Sanders

Ian
mine is a factory shell and I needed to cut about 1" to make room for the kenlowe.
Paul
Carb ices up when outside temp is between about 2 and 5 degrees. When the weather is actually below zero it seems OK. Not that I drive it much in the winter.

Cheers
Mark

Ian,

The fans fit without bodywork mods, they need a little trimming and allowance for bonnet catch, and need the rad out to fit.

Mark,

I used to find that with 3.5 it would nearly try to stall coming off Motorway at end of slip road. I would think some rad blinds would prevent this occuring.

Paul
Paul

Cooling was always an issue when stationary with my 3.5 and more so when I upgraded to a 4.6. I went through all the usual stuff, exhaust wrap, special antifreeze mix (distilled water, water wetter and 20% antifreeze), bonnet louvres and tapping holes into the back of the heads to improve circulation. The one thing that made by far the greatest difference was outing the 'uprated' V8 rad and having an aluminium one (as big as would fit) custom made by Pace Rads. Cost me about 280 from memory. For different reasons I've since moved to custom made RV8 style manifolds and can only imagine that this has improved the cooling performance still further.

Re Xstream tops, I bought one from the US about 2 years ago. Took about 4 months to arrive due to supply problems. Finally got around to fitting it last week in time for a blast up to Silverstone on Saturday. The difference in top end performance is incredible. A rolling road session had shown that the 2"x14" pancake filter wasn't flowing enough air above 3500-4000rpm but I wasn't expecting such a transformation. The Xstream filter wouldn't fit in conjunction with my existing filter so I had to buy a K&N one to suit. I'll try and track down part numbers and height info tonight should anyone be interested. I can't really commnet on icing problems as it's Summer use only.

David.
David Canning

What sort of costs do the Ali rads work out - and where do i go to get one?
ian sanders

Ian, do a search on Frontline, they're in Avon, also Pace who will make to your spec, IIRC they are in Norfolk.
HTH
David S

I built mine myself. I bought core to Pace product. Pace make your radiator if you want. www.paceproducts.co.uk. Also www.cambridgemotorsport.com.
Regards.
http://membres.lycos.fr/mgcontact/fileupload/uploads/1091315172_alyrad.jpg
michel

Ian,

Fronline (also have Pacet fans)and MG Owners will have them off shelf perhaps
Cost see link
http://www.mgocaccessories.co.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2emgocaccessories%2eco%2euk%2facatalog%2f&WD=radiators&SHOP=%20&PREVQUERY=SS%3dradiators%26ACTION%3dGo%2521%26PR%3d%2d1%26TB%3dA%26SHOP%3d%20&PN=MGOC_Accessories__Radiators___Oil_Coolers_140%2ehtml%23aG358#aG358

Cambridge Motosport will make them up on request using PACE products If I remember correctly.

Paul
Paul

As I mentioned, I paid 280 for mine through Pace. Take your car down there if necessary. They're very approachable and give good advice. They can also make up a rad with mounting points for the fans.

David.
David Canning

This thread was discussed between 24/07/2004 and 02/08/2004

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