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MG MGB GT V8 Factory Originals Technical - How much power within the Speed Championship Regs?
|I'm doing some arm chair research into running a V8 in the Group 2 of the Speed Camp, as an addition to the family means the Sprite will become less practical.|
The MGCC 'Group 2 (Road Modified A)' class permits the following modifications;
* Free air filter
* Ported carbs & manifold but original castings
* Modifed head retaining standard valve sizes
* Free exhaust manifold & system
* Free cam
This spec appears to be limited by the standard valve sizes. The question is, how much power would this spec with a suitable camshaft give? With regard to cam, what timing would a suitable cam have?
Pls bear in mind also that the most likely route for the heads would be standard casting and valves with cleaned up seat detail i.e. smaller 3 angle seats to provide a slightly larger port behind.
You should find that the carbs limit the output at about 220/230 bhp. Driveability should be your main concert rather than max power.
Check on whether the V8 is allowed thesame mods as other cars in the class - it may have a seperate list of permitted changes.
|I would be surprised if you got much more than 200BHP on the blockhuggers/SU manifolds but talk to Malcolm Beer|
|DB - no special restrictions on V8 mods, James is a current competitor and has done his homework on the regs. |
James - however further examination may be needed to discover if RV8-style manifolds are legal or not, ie can you chop holes in the inner wings ?
Handling and grip will be all-important, you could do worse than chat with Bruce Morgan of MGCC Southwest centre who is current custodian of Dave Franklin's old car which is roadgoing and won the BCV8 race championship some years back among many other competition successes.
|Out of interest, what are the gearbox and final drive regs.|
Can you use alternative gearboxs or a lsd?
I was just surprised to see that the cam is free, my initial thoughts for a spec are :-
as much compression as you can get !! 11:1 or more
gas flowed heads with valve guides shortened to get 500 or more thou lift
crane 234 or 238 cam, if you want to use lots of rpm try a 256
If you want to see my approach to things using a standard engine I hope to be at Brands for the MGCC race meeting on the 4th oct - car 11 in the Total Butler series.
|RGM 'A' regs - original type box in its original position, ratios free (but no straight-cuts). Original axle /diff casing, internals free but no LSD unless one was originally fitted standard.|
|This is going a bit off topic but allowing a V8 gas flowed heads and free cam is a good recipe for busting the original gearbox which is not a cheap item to replace IMO.|
Many thanks for the info. Dave Smith - I know Bruce I've taken a few Autotesting prizes off him before moving to the Speed Champ..
Dave Broke - your thoughts on cam choice are duly noted, I would have thought that 280 degree cam would probably be as far as sensible to go and maybe even 10/15 degress too far.
Concensus appears to be in the order of 200bhp which I would imagine is sufficient to move in style!
I don't know what that suspension tuning rules of thumb are for a Sprite but on a B either s4 or V8 you want to be stiff at the front but relativly soft at the rear. Otherwise you will find on a sprint with tight corners you will be picking up the inside rear wheel. This happens as the front outside corner goes down and the car effectivly tilts on diagonal axis. So keeping the front outside corner up and alowing the rear inside corner plenty of droop enables you to get the power down earlier.
The limiting factor in stiffening the front end is that doing so can increase the understeer tendancy. This can be managed with tyre and pressure choice and, if your class allows, negative camber front lower wishbones.
The standard cam is always quoted at 285 degrees and 390 thou valve lift.
Most of the less extreme performance cams get the valve open further and hence don't need to have as much duration to get the extra flow through the valve. Since the regs for the speed championship allow a free cam I would seriously look at building the engine to produce power at higher rpm - not the traditional way to build a V8. This way you can limit the torque of the engine while still achieving a high power output and reduce the strain on the transmission and tyres.
Of course this might not make for a sensible car to drive to events !!
This thread was discussed between 23/09/2003 and 30/09/2003
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