ambrose@cts.com" "David Ambrose" at 11-JAN-1995 16:37:18.28 wrote
> Subj: RE: MGB Shocks
>
> Hey Byron,
>
> Would you mind telling us about this MGB? This sounds *really*
> interesting.
>
> Dave "Maybe I should do this?" Ambrose
> Play it cool, play it cool, fifty-fifty fire and ice.
> Dave Ambrose ambrose@cts.com
So here you have it...this is made up from other bits because I hate re-typing
things....Some is a repeat of before so please excuse that....
If anybody has anymore questions etc i'll be happy to chat via e-mail
thanks
Byron
I'm building/heavily modifying an 1967 MGB roadster. The cars been
being built for many years now and is probably only 9 months from
completion.
Since the list of changes is too big to mention completely I'll just
give a quick overview (MG purists should leave now 8-) )
Body: Removal of all trim/bumpers. addition of front spoiler.
Entire body/chassis back to bare metal and painted with the
Midnight Blue of the current Honda Prelude.
Chassis: reinforced and seam/stitch-welded. Full Chrome-Moly roll cage.
Diff: Cut down ford 9" with aluminum centre and full floating axles.
Gearbox: Getrag 5 speed..same as what came in the BMW 635CSI
Motor:
The motor is an 1984 block...with the 4.4L crank from the local leyland V8.
We had to remove some bits from the crank counterweights to make it
clear the block. Bore is left at 3.5L size so we can retain rigidity
in the block. The bottom end has a girdle that incorporates the main
caps..Once again for strength....The rods are late model rover (89' I
think) . Pistons are custom made from cosworth blanks with gapless
rings. The Valves are Chevy....I can't remember exact sizes , but their
as big as you reasonably can go...The valves, combustion chamber and
piston tops are all ceramic coated..This gives us higher combustion
temperatures and means less heat escapes through the piston...meaning
the oil runs cooler...cool enough to not need an oil coiler....The
rockers are Australian made Yella Terra roller rockers ...very good and
blood expensive. The crank is some yank grind about 290 duration and
about 550thou lift...This cam gave 430hp in a
EFI 5L GMH V8 here running on hig octane unleaded. The motor still
idles fine and has heaps of low down grunt....We were going originally
as mentioned before use a roller cam with 350 duration at about 600thou
lift...a nice wild cam...we could still use it but we had to get the
cam made in the US and coupled with roller lifters blew cost by another
A$2500...Redline will be about 6500 max...
The bottom ends runs a 3 stage dry sump pump made by moroso...the sump
is made by my friend...we are removing the original oil
pump/distributor combo and running seperate oil feeds to the top if the
motor...
Induction is with a plenum chamber setup running into a hand made
manifold with 8 throttle bodies and 8 injectors..coupled with the MOTEC
system..This system is the same one used by the V8 touring cars at
Bathurst (OZ)...Timing will be crank triggered.....
We are removing the water pump housing and using an electric water
pump. The water pump flows 30 gpm and with a thermostat allows quick
warm up and cool down if required. Water will run in the reverse
direction as is done on most new cars (opposite of normal)...
A plate across the front of the motor will incorporate engine mounts ..
This is like what the put on drag cars...The cam will come through the
plate and we will be using a rubber belt to the crank like on the 2L
escort motors used to have...This allows me to adjust cam timing very
quickly...retarding both cam and spark timing will allow the motor run on
normal fuel...advancing both cam and spark timing will allow the motor
to run on 104 octane and run much more boost....
The rear of the sump will incorporate small engines mounts to take load
off the bell housing....
We have found a chap who will make us Kevlar rocker covers and
a plenum/air box...The standard rocker covers are'nt high enough for
the new rockers etc...These look very cool and I've seen similar on
some of the local touring cars...
The Turbo sits out front in a manner similar (if not identical) to a
turbo buick V6, and will feed into the plenum chamber...
The motor has not been dyno'ed yet...we are waiting on money for the
computer brain to run the EFI and for the turbo's to become available.
The turbo's are only available in the US.
Total cost of the motor is about A$16000-A$18000
I redid the HP calculations yesterday (13-NOV-94). Running 9:1
compression and without a turbo the motor should give about 350hp..
Adding the turbo with 5psi of boost (.33bar) should give by my
calculations about 450hp on 94 octane leaded fuel...
With 104Octane aviation fuel and assuming the motor can handle one bar
of boost (14.7PSI) we should in theory get 700hp.....
The formula's I looked at give you a 100% increase in power at 1 bar
boost because you are adding an extra atmosphere's worth of pressure...
This sounds reasonable , but I doubt that the motor is going to
withstand 1 bar of boost???....Compression at this boost level is about
18.5 to 1...a hell of a lot....I guess we'll wait and see..The 944
turbo motor my friend is racing runs 1.5 bar of boost without hassle..
Though there static compression is about 8:1 or lower..
A further update to this (11-JAN-1994)...1 bar of boost won't give a
100% HP increase due to thermal losses....The Buick V6 turbo's run
up to 20+psi of boost without trouble...A normal buick V6 has 8:1
compression and will run 14psi of boost on street gas...so in mine
(9:1 compression) boost of about 10psi on the street should see plenty
of (un)-usable HP. On 100 octane gas I may be able to push boost to about
15psi or more.....The computer will tell me when to stop or perhaps the
crank will....I may buy a steel crank if needed later
Suspension:
Rear: 5 link rear end with coil-over shocks/springs
Front: Hand fabricated front crossmember/A-arms with Magnesium uprights
etc
The reason's for the front crossmember change are numerous , but the
main one is that to get everything to fit we either needed to move the
engine back about an inch (ie chop the firewall) or move/modify the
crossmember. As you all know the crossmember is huge..a smaller lighter
one similar to what you can get aftermarket for hotrods will give us
the room and other benefits..The crossmember is being done by a local
race shop. The layout is based on some late 60's sedan racer and is
still fairly state of the art for this type of suspension. This
shop use it on their 600hp chevy power sports sedan. basically a
chassis with a fiberglass body. Its real nice, has adjustable everything
and comes with magnesion spindles which allows the big brakes etc..
This may/will allow us some more room for the tyres..though its pretty
hard to guess what will fit and won't ..especially at the moment with
the original front suspension not on the car..
Brakes:
Rear: Ford 11" ventilated discs with single spot calipers.
Front: 13=" ventilated discs with 4 spot porsche calipers
Performance: 0-100: 3-4 seconds estimated
< mile: 11.00 seconds at about 120Mph with 400hp.estimated
< mile: 9.5 seconds at about 150Mph with 600hp .estimated
The car will be road-registered and road-driven (In Australia)...
I intend to do hill-climbs,drag racing, road-rallys and juts plain
drive it.
The bit missing from above of course is wheels. This is where I'm
looking for help. The rear end will run slight tubs and I will be able
to fit 10" wide rims with a 255-265 width tyre without problem.
On the front is where I'm stuck. Simmons wheels in Australia make
beautiful 3-piece magnesium wheels so my brand is pretty much fixed.
I want to fit 18" x 7" wheels on the front with a 225 width tyre, since
this is the skinniest 18" tyre you can buy (as far as I know). From
looking at the MG and various books I reckon a 205 is a pretty tight
fit. I can fold/remove the front guards inner lip ,and given the
suspension will be fairly stiff ,and also hand-made with wheels made to
any offset I desire, I reckon the 205 should fit no problem....The 225
may be another story however. Given the money I'm spending I'd love to
fit the 18" rims.
Has anyone experience/advice concerning 205 or larger width
tyres????...I've seen stacks of pictures of MG race cars and they would
appear to have very wide tyres on the front....On a race car however
maybe a little bit of tyre fouling is acceptable....
Current estimates put the finish time at July-August next year. So it
should be in Sydney by early September at the latest...
The current state of play is:
The bellhousing is being made and we are going to get the gearbox and
engine placed in the car before we go any further...
Front calipers arrive at the end of this month..they're from a 944
porsche and are very light, and you can get a good range of pads for
them.
The front end is due to be constructed in Jan-Feb...I need to buy the
wheels before then and the front disks...
The rear end will follow in March
By end of March all mechanical components should be in...
The roll cage will be added
The car will then have the interior fitted and the stereo positioned.
The car will then be stripped and sandblasted prior to painting. Paint
is being done by a chap who is Roll's Royce certified.
The car will be painted and then all the stuff will be put back in/on.
by Jul-Aug it should be ready to shipped to Melbourne for licensing and
then onto Sydney..
Thats all for now..
Byron
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