MG Sports Cars

engine swaps and other performance upgrades, plus "factory" and Costello V8s

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v8bloke
Mark Rawlins

(73 posts)

Registered:
02/02/2010 02:13PM

Main British Car:


Re: 4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: February 07, 2010 10:00AM

Johnny
Wheels are made by Compomotive ML with special offsets. 15x7 fronts(ET5) and 15x8 rear (ET3)

Axle is stock MGB with 3.07 and quaife LSD

Springs are the best handling upgrade ever. Composite from Doug Jackson.

Brakes are Wilwood superlite with 298mm vented discs up front and Ford Cosworth 4x4 calipers with vented wilwood discs at the back.
Also made a Bias pedal box with dash adjuster.


MGBV8
Carl Floyd
Kingsport, TN
(3433 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: MGBV8
Date: February 07, 2010 10:59AM

"Springs are the best handling upgrade ever. Composite from Doug Jackson. "

Really. I've heard of problems with those delaminating when used in high horsepower MGs.


v8bloke
Mark Rawlins

(73 posts)

Registered:
02/02/2010 02:13PM

Main British Car:


Re: 4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: February 07, 2010 12:40PM

""Springs are the best handling upgrade ever. Composite from Doug Jackson. "

Really. I've heard of problems with those delaminating when used in high horsepower MGs."

Well Ive been using them since 2001 and have been very impressed.
I think its important to have some form of axle location and anti tramp bars that fit properly without binding as the suspension moves.
In fact I have bought a second set for spare.

I have seen a set shear at the thickest part just in front of the axle and think it was due to Anti tramp bars that didnt follow the same arc as the axle movement.

Has anyone got more information on the delaminating?

Mark


Mr. T
Tony Andrews
Kent Island, Maryland
(153 posts)

Registered:
10/23/2007 03:59PM

Main British Car:
'75 mgb, '74 grille, morspeed bumpers Rover 3.9

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: Mr. T
Date: February 08, 2010 09:54PM

Johnny,

If that's your car in the avatar, you've got an interesting hood scoop - appears to be an rv8/ford hybrid?

Maybe you could start another thread with a few pics.

Thanks, Tony

p.s. apologize for the quick migration off topic.


v8bloke
Mark Rawlins

(73 posts)

Registered:
02/02/2010 02:13PM

Main British Car:


Re: 4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: February 09, 2010 03:51PM

Here is another vid for those interested. Edited from 2009 trackdays.




Thanks
Mark


johnny wells
johnny wells
fairfax, virginia
(17 posts)

Registered:
08/15/2008 08:56AM

Main British Car:
76 BV8 Rover 4.2

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: johnny wells
Date: February 10, 2010 09:29AM

Tony -- I'll hit the hood scoop over on the scoop thread already going.

Mark -- More questions, if I may.

Would like to see pics of the Cosworth rear disc brake set up on the stock MGB axle. That sounds very interesting.

I assume you're running the wider disc wheel Salisbury axle (rather than the narrower wire wheel axle). And no mods to the axle shafts, eh?

Would also like to see your modified pedal box. I'm thinking of doing the same.

Now, are you running the stock MGBV8 transmission or did you go to an SD-1 or something different?

Thanks!

Johnny


v8bloke
Mark Rawlins

(73 posts)

Registered:
02/02/2010 02:13PM

Main British Car:


Re: 4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: February 10, 2010 11:30AM

Johnny
Yes am using the steel wheel axle.
My first rear disc conversion used solid Rover 800 rear discs with 2wheel drive sierra cosworth calipers and although they worked well the heat generated under extreme conditions fried the pads and the discs would crack severeley.
Having made the discision to use Vented discs I couldnt find donor discs with the right dimensions so decided to use wilwood ones 11 inches diameter and 0.81 thick. These were bolted to purpose made alluminium bells (which also act as wheel spacers). Then the Cosworth 4x4 calipers were bolted to a custom ally bracket.
The result was that the pads would now last 12 months and the discs are hardly wearing at all.
I will take some pictures at the weekend and post them up.

Gearbox is the R380 2wd. The stock MGB V8 box is VERY fragile and a complete waste of time.

Mark



Phillip G
Phillip Leonard
Kansas City
(395 posts)

Registered:
02/03/2008 04:12PM

Main British Car:
1992 MG RV8 Rover 3.5

Re: 4.6 GT V8 Modified for road & track
Posted by: Phillip G
Date: February 11, 2010 09:03PM

V8Bloke,

What incredible fun and it looks stock, almost like off the show room floor !

It's a race car - no - it's a street car ! Is it right hand drive ? Is their a friend sitting next to you in the passenger seat ? Looks like it. That is the bravest guy of all.

very best regards,

Keep them on the track,

Phillip G


v8bloke
Mark Rawlins

(73 posts)

Registered:
02/02/2010 02:13PM

Main British Car:


Re: 4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: February 12, 2010 12:20PM

Phillip
Yes it is Right hand drive. My friend in the passenger seat is in the process of building his own MGB to the same specification.
The car is road legal.


kurisu_4u
Chris Hardy
Belgium
(3 posts)

Registered:
02/11/2011 06:29AM

Main British Car:
MGB GT V8 3.5

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: kurisu_4u
Date: February 11, 2011 06:39AM

Hi Mark,

Nice car and impressive performance + the fun of the rear end breaking out ...

I am curious about your suspension setup. Do you have trailing arms with composite leaf springs ? Panhard rod, too ?
I have the Frontline Costello setup and it will require some adjustment. Too much understeer and will sometimes break into oversteer ...

Looking for a proper engine and gearbox, too.

Keep showing the way to modern and more expensive cars !!!

Chris


crashbash
david bash
st. charles
(215 posts)

Registered:
01/28/2008 10:53AM

Main British Car:
1979 MGB Rdst V8 project, 1968 MGC GT, 1969 MGB Rd olds 215

Re: 4.6 GT V8 Modified for road & track
Posted by: crashbash
Date: February 11, 2011 12:08PM

Wow! Mark
More videos please..........3d next time
Curious what rpm you are reving the motor to on these videos and what you consider red line. What kind of parts have you got in this engine? forgive me if that qustion has already been asked

Then how comfortable is it on the street? I would think it doesn't have to be too comfortable because of the fun factor. Have you done any long distance club ralleys. Does law inforcement over there tend to pick on cars like yours on the street or thumbs up and pull you over just to see what's under the hood/bonnet

thank you for shariing
dave bash


castlesid
Kevin Jackson
Sidcup UK
(361 posts)

Registered:
11/18/2007 10:38AM

Main British Car:
1975 MGB GT Rover V8 4.35L

Re: 4.6 GT V8 Modified for road & track
Posted by: castlesid
Date: February 11, 2011 06:50PM

For Chris Hardy. Mark, apologies for hijacking your thread, hope all is well with you and the car.

Frontline front or rear or both?

Sound like you have a rear anti roll bar. I have found the most balanced set up for the road is, Front 480lb springs 7/8th anti roll bar and for the GT rear end the Moss MGS 40721 reverse spring eye rear leaf springs rated at 110lb ( lowers1 1/2"-2") with either well rebuilt standard lever arms or well matched telescopics ie not spax.

I have some older Monroe teles that were fitted with a rear anti roll bar, the car was lethal with snap over steer.

After the front end rebuild with the Moss coil over kit, I fitted the above mentioned springs and removed the anti roll bar but retained the Monroe teles, result, the car is transformed it is now beautifully balanced and the level of grip is amazing, wet or dry, this with the same 195/60 Pirelli tyres on 6" x 15" KN Minilte style wheels.

For a bonus the ride is also greatly improved as the rear springs are much more compliant but as they are almost flat they do resist lateral movement so for road use a Panhard bar is unnecessary.

Kevin.



Edited 1 time(s). Last edit at 02/11/2011 06:59PM by castlesid.


kurisu_4u
Chris Hardy
Belgium
(3 posts)

Registered:
02/11/2011 06:29AM

Main British Car:
MGB GT V8 3.5

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: kurisu_4u
Date: February 17, 2011 02:39PM

Hi Kevin,
Thank you for your input. I suppose you removed the rear antiroll bar.

My car has the Costello Frontline both front and rear, with Bilsteins at the front and Harvey Baileys at the rear. I understand from my dad that Harvey Bailey actually designed this rear suspension setup in the seventies.
I have a ¾" antiroll bar at the front but none at the rear.
A Panhard rod is fitted at the rear and I guess it is necessary on this particular setup with trailing arms and coilovers.
I am not very confident at Spa-Francorchamps as the car was having a noticeable twitch of the rear going into the « Raidillon » (don’t want to lose it there) ; but was fine everywhere else, apart from the understeer. May be something’s loose and I ought to check it.

I think the heavy understeer comes from a soft rear setup and stiff antiroll bar at the front.
Front springs seem to be the stock items as the front is quite low and seems to have very little travel (bottoms out on the road). A friend of mine has different springs, so I will have a look at this … or go for 600lbs ones.

Wheels are Minilites 8" x 15" with Yokohamas 225/50 and 245/50

Engine is the P6 « flexible » type (10.5:1 compression ratio) with RPI 285 camshaft and Weber 500 carb on an Edelbrock Performer manifold. Exhaust is the tubular bloc hugger type, so not very good for horsepower. The engine really revs easily to 6500 and I once hit 7500 by error. Bought a rev limiter to avoid going over 6000 since (not good for the main bearings).

Didn’t really take time to drive the car these last 3 years as I rather chose to ride bikes. Missing it now, and will sort it soon.

It’s meant to be a trackday toy, so comfort is not the aim.

Cheers
Chris



Edited 1 time(s). Last edit at 02/17/2011 02:44PM by kurisu_4u.


castlesid
Kevin Jackson
Sidcup UK
(361 posts)

Registered:
11/18/2007 10:38AM

Main British Car:
1975 MGB GT Rover V8 4.35L

Re: 4.6 GT V8 Modified for road & track
Posted by: castlesid
Date: February 20, 2011 08:45AM

Chris,

Just checked the Fronline site and there appears to be no camber adjustment for the front end kit so what you need for track use is a set of negative camber lower wisbones, these will give approx 1 1/2 deg. of negative camber and reduce the understeer considerably, again for track use the 600lb springs are the usual way to go, the 3/4" anti roll bar is probably not stiff enough! a 7/8th or 1" is the norm for track use.

Also for track use if the front end is properly sorted a small but preferably adjustable rear anti roll bar can be beneficial

With a "B" to have the front stiff and the rear soft is the best set up, what sort of ride height do you have. is your car based on a chrome or rubber bumper model? if rubber then to correct the increased ride height of the crossmember (1 1/2") you can get dropped spindles from the states from Fab Tech, lots of good suspension advice ther too.

You can get the neg. camber arms from Doug smith at MG Motorsport, he knows Spa like the back of his hand and certainly knows how to make a MGB stick to the road and is very happy to have a chat, you can trust what he tells you.

Kevin


pspeaks
Paul Speaks
Dallas, Texas
(698 posts)

Registered:
07/20/2009 06:40PM

Main British Car:
1972 MGB-GT 1979 Ford 302

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: pspeaks
Date: February 20, 2011 11:10PM

Johnny, I love the look of your car! Did you make or buy the hood scoop?


"P"



kurisu_4u
Chris Hardy
Belgium
(3 posts)

Registered:
02/11/2011 06:29AM

Main British Car:
MGB GT V8 3.5

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: kurisu_4u
Date: February 23, 2011 07:32PM

Hi Kevin,

I forgot to add that the car has Frontline castor angle wedges, reducing the castor angle by around 3° if I'm correct.
Doug Smith is a nice guy. I had the chance to meet him at Spa a number of years ago during historic races.
Will take the time to talk to him.

My car's the rubber bumper type but I have no idea yet what the springs nor the ride height are. Where do you measure the height ? Front fenders are modified, so it's difficult to compare with a stock car. Distance from the center of the hub to the top of the wing is 51cm (20") at the front and 56cm (22") at the rear from the center of the hub to the bottom of the side window. I think it is rather close to the rubber bumper height.

And you are right about the anti-roll bar. 3/4" seems too soft as the car leans quite a bit as can be seen on photos.

Tank you for your advices
Chris


v8bloke
Mark Rawlins

(73 posts)

Registered:
02/02/2010 02:13PM

Main British Car:


Re: 4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: March 01, 2011 05:40PM

Sorry guys Ihavent visited the forum for ages.
Merlin heads are now fitted along with new exhaust system.
Here is a clip from Silverstone F1 circuit mixing it with 500bhp+ cars



Same session taken from the Evo with the graphics.



Car is going very well with 326bhp now.

Mark


v8bloke
Mark Rawlins

(73 posts)

Registered:
02/02/2010 02:13PM

Main British Car:


Re: 4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: March 03, 2011 04:02AM

To answer a few questions
Dave Bash
I have a Digital race electronics rev limiter which has a maximum RPM recall feature and according to that it tops out at 6400rpm although max bhp it mate at 5800rpm. The car has evolved over the last 10 years which is when I first started doing track days. I wanted to keep her road legal so I could drive to my local track about 30mins away. I have adjustable shocks all round with fairly stiff front and fairly soft rear springs. If I drive on the road with track settings it is fun but very bumpy and the car tends to hop about over rough road surfaces. with the shocks softened off a few clicks its not too bad. The seats are moulded fibreglass with no padding at all and they are actually very comfortable even on a 100mile trip and weigh 4.5kg each. With a race/rally solid lifter cam it doesnt like cruising below 2000rpm and above 3000rpm the performance is violent.
I drive about 5000 miles a year and have only been stopped once for speeding which is fair enough. I generally stick to speed limits though.
Handling is generally very good with no understeer at all, the front end is like on rails but the rear tends to break away too easily.
I have tried removing my custom rear ARB which improved the oversteer but I felt the car was much more unstable generally, so bar is back on. Latest mod is that I have lowered the panhard rod by 2 inches ( was along centreline & paralell to the axle) to lower the rear roll centre but have yet to test it.

Cheers

Mark


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5566 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: BlownMGB-V8
Date: March 03, 2011 12:05PM

Need fatter back tires. :-) :-) :-)


v8bloke
Mark Rawlins

(73 posts)

Registered:
02/02/2010 02:13PM

Main British Car:


Re: 4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: March 07, 2011 03:47PM

Jim
If only!

265 or even 285 would do the trick.
Would love to try some slicks but again sizes are restricted with 15" wheels.
Next trackday is 21st March on the F1 circuit at Silverstone, so should see if the lowered panhard bar is an improvement.

Mark
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