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MG MGB GT V8 Factory Originals Technical - 300hp+

Anyone making this sort of power from the Rover V8.
What specification would the engine have to achieve this output?
Hankering after more power!

cheers

Mark
Mark Rawlins

The Rover engine can be built to deliver more than 300BHP, but your MG would be a pain in the nether region to drive in traffic. The RPM at which you generate any power increases and the power band decreases as you increase the horse power. The high octane petrol needed also will become difficult to find in the not too distant future, even in the U.K. Getting the horsepower you want and keeping the car streetable would be easier if you went supercharged or turbo-charged rather than naturally aspirated, or you could use nitrous for occasional power bursts. I don't recommend nitrous, but some would argue that you can use it on a stock engine, and if you blow the engine and replace it a couple of times you have spent less than you would building a pukka high performance lump. Another problem would be getting the power to the road as it does little locked up under the bonnet.
George B.

Mark,

Frontline are working on 5L with wildcat heads at a guess may get to 400bhp. Downside is heads cost nearly 2k and you will need a new exhaust manifold.

Paul
Paul

George,
Any idea what superchargers could be made to fit? I dont have FI. Can I pump air through the 4bl edelbrock 500?
Paul,
What are wildcat heads and where can I get more info.

Cheers.

Mark.
Mark Rawlins

Mark,

I would suggest you check out RPI web site as supercharging is not recommended and big valve heads may require a few other mods.

If looking for a race machine then someone like John Eales can push up HP or talk to Tim at Frontline about wildcat heads, his web site has not been updated recently (still Spridget orientated) but he has teamed up with Ken Costello and is putting together lots of goodies for v8. It does get expensive going over 300.

Paul
Paul

Mark,
I don't know what superchargers are available in the U.K. In North America and in Australia the G.M. or Holden 3800 V6 engines have superchargers that would be a good match as these are refinements of the 3.5L V8 Rover engine. These engines have electronic controls such as knock detectors and fuel injection, so adaptation would be difficult. The easiest way to supercharge is to suck the air through the carburetor, otherwise an airbox surrounding the carb may be utilised. Another problem with the supercharger is where to put it in the MGB's already crowded engine bay. A bonnet scoop would probably be required. As has been stated, over 300 H.P. won't be cheap.
George B.

Thanks for the onfo
At present I am getting about 250 at the flywheel with my 4.0L, I wonder how much increase I would get by going to 4.6 or even 4.8. Real Steel do a stroker kit for 1500 approx but I dont want to spend that sort of money for just a few HP. The good thing is my 4.0L has a crossbolted block so should cope with extra power.

Mark
Mark Rawlins

Is this engine in a B, and do you drive around town in it? What would you do for ballast? Where do you buy tyres? 250's not enough? Where are you coming from and please let us know where you're going and keep us posted. Sounds like a real drag or a tractor pull! Was that an F-40 way back there?
Angus

Mark, The "Sprintex" looks compact (in photos) and can likely be plumbed in with some sheet metal mods-- a bump here or there. I see a scoop in your future. Far out!
Angus again

That's on an EFI. Looks like $$$. How bout a Chev small? Did I mention $$$(keybaord won't do lbs). Something's going to break on a stock train if your going to really use it!
Angus yet again

Angus

Yes the 4.0L has been in the B for a year now great fun to drive. The transmission is fine (R380 box) with quafe LSD 3.07:1 axle. I am using composite springs with panhard rod and anti tramp bars. Traction is very good with Bridgestone 205/55 15 So2's, even in the wet.
The car is road legal and I have started sprinting/hillclimbing.

Mark
Mark Rawlins

Everyone with a 215 BOP who is interested check out this site: http://www.blowerdriveservice.com/blower_comp_kit.html

Something to think about.
Michael S. Domanowski

Hi Angus

NON MG oriented, but if you want to do - then hold the Alt key down with one finger and type 156 on the number pad - release the Alt key and you should have a sign.
Chris Betson

Mark/Angus

I use my 4.6 everday, easy to drive round town just leave in 5th. I've only had it on a rolling road, but similar spec to MG Owners so about 285bhp, but use Real Steel Stumppuller cam. I'm thinking about wildcat heads but may need uprating a few internals and changing to smaller K&N filter I'm happy to let Tim do the research.

Paul
Paul

Just over 10 years ago I was involved in the sourcing and setting up of a race TR7V8 which went onto win the Cox and Buckles TR Overall Championship three times in succession. This was with a base 3.9 litre engine, originally with Crane 248 cam, Pete Burgess (well modified) heads and a standard 3.9 Lucas single plenum, single throttle injection system. Doubters said 300 bhp wasn't possible from the single throttle, but development soon reached 312 and it went up from there by about another 20, but I didn't actually see or drive the car in the later spec.

With 312bhp at the flywheel (on JE Engine dyno) the car would pull max revs in 5th (restricted to 7k) and with the gearing that was 165mph with a long enough straight. The car was clearly lighter and somewhat significantly altered in suspension spec etc, but the point connecting with this thread is that it could be driven quite normally and only the competition clutch made the progress anything other than perfectly useable on the road. Idle was smooth as was pick up from idle to max revs. The clutch made take up gently difficult, but if you engaged fully and then dragged the speed down to show sub 1000rpm it would take full throttle, even if it wasn't a responsive from there as a standard 3.9 is.

So the answer to the question is quite simply that yes it is quite possible to achieve 300bhp and retain operating conditioons that are perfectly road compatible. Do remember that engine managment helps alot, but that even with 300bhp it is still only a not very dramatic 77bhp per litre!!

Rog
Roger Parker

This thread was discussed between 22/12/2001 and 24/12/2001

MG MGB GT V8 Factory Originals Technical index

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