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:


4.6 GT V8 Modified for road & track
Posted by: v8bloke
Date: February 02, 2010 04:32PM

Hello All

Just stumbled across this forum and thought id say hello.

I live in Wiltshire, England & Over the last 15 years or so I have been improving my factory V8 for track days.
Weight is down to 970kg and making 293bhp (more to come this year).
Here is a clip of the car at a track day. Rules are, no overtaking on corners and only overtake on the right side.




[www.youtube.com]

Ill post some pics when I have more time.

Thanks for looking
Mark


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5626 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: February 02, 2010 05:22PM

Great clip! Your car has a delightfully viscous undertone, I'm sure it is an absolute joy to drive. Just guessing you could make good use of a bit more grip at the rear. (Couldn't we all?) There's just something magical about 300 horses in an MGB, and your video does about the best job of capturing it of any I've seen.

Jim


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 02, 2010 09:10PM

Hi Mark,

Welcome to the even darker side. you'll find a few of us Brits lurking in here me, Perry also from the V8 Forum and a few more who possibly didn't realise it's a US site because of the name.

I'd seen the clip before but untiI I put it on full screen hadn't seen how much you were sliding the car around, strangely in the clips that appear at the bottom of the screen there was a certain Mr Blackwood going rather fast round a car park and what a lovely noise that blown 215 made Jim. look forward to when you get that 340 engine fired up..

regards.

Kevin.


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 03, 2010 04:28AM

Thanks guys.

Car does tend to oversteer when driven hard.
I have a 1inch front sway bar and a 5/8 rear sway bar (my own) and have tried various other setups.
If I increase the rear stiffness it oversteers even more. But when I reduce the rear stiffness it understeers less but is no where near as stable at speed over 120mph (read dangerous). I never experience understeer and am very happy with how the front turns in. Car weighs 970kg 52% front 48% rear so weight distribution pretty good. Perhaps this is as good as it gets with live axle.
Although it is slightly tail happy the car is very forgiving and it is quite rare to spin me out (unless its wet).

Finding this site really interesting.

Kevin
We must put faces to names sometime.

Mark


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 03, 2010 07:26AM

Mark,

Yes that would be good, I haven't been out and about with my MG due to health issues last year but hoping to get out there a bit more in 2010

Do you ever do a track day at Brands as that is just down the road from me?

Yes a very good forum with a load of great guys, have you found the engine & transmission section, if not run your cursor up to the web forum and click on web forum hub and scroll down, for some odd reason this not accessable from the drop down menu.

Kevin.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5626 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: February 03, 2010 11:31AM

It should be there Kevin, labeled, "Drivetrain Issues"?

Mark I was referring to your wheelspin exiting the corners, the handling of your car looked spot on, to me at least. But oh my, all that power! (Don't cha just love it?)

Kevin, it's odd but I couldn't find the one you referred to. Do you have a link by chance?

Jim



Edited 1 time(s). Last edit at 02/03/2010 11:35AM by BlownMGB-V8.


mindseye
John Csuhany
Edmonton, Alberta, Canada
(76 posts)

Registered:
11/18/2009 11:40AM

Main British Car:
1980 MGB 1962 Buick 215 cu. in.

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: mindseye
Date: February 03, 2010 01:10PM

very nice clip....sounds really good, like a race car should, because of the exhaust I have in mine it sounds more like a muscle car but that is ok too.....I am curious as to what kmph you have topped it out at?....300 hp in an mgb has got to be ridiculously fast



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 03, 2010 02:02PM

Jim
Problem is wheelspin = tyres dont last long.

John top speed in that clip according to speedo 140mph but sat nav says 132mph
Would be interesting to see what it would top out at with a long enough straight.

Car in bits at the moment.
Fitting new Merlin cylinder heads.
Grafting on Golf (rabbit) Mk1 wheelarches to the front.
Custom re wire.
New complete exhaust system 2.5 inches from 2.25

Thanks
Mark


MGBV8
Carl Floyd
Kingsport, TN
(3471 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 03, 2010 04:04PM

What size 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: February 03, 2010 05:21PM

Carl
Front 205/50/15
Rear 235/50/15


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 03, 2010 05:50PM

Jim,

Strangely I can't find it now but obviously someone has put it on you tube, it was in the links that yiou can bring up at the bottom of the screen, there were a load of BV8's

Kevin.


rficalora
Rob Ficalora
Willis, TX
(2538 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: 4.6 GT V8 Modified for road & track
Posted by: rficalora
Date: February 03, 2010 05:53PM

RE: Rear 235/50/15

I was able to find 225 & 245/50/15, but not 235/50/15... what brand/model tire are you running?


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 03, 2010 07:26PM

Welcome Mark - I've seen your vid a couple of times prior to your post - I can't seem to get enough of mg's with v8's!


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 04, 2010 02:43AM

Rob
Using Toyo R888 235/50/15

Tony
I know what you mean, they seem to be somewhat addictive. In fact 2 of my friends are building copies of my car after some passenger rides got them hooked.
Build cost is in the region of 10k.

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 04, 2010 06:12PM

Mark,

Pictures, please. Lots!

Regards,

Johnny



MGB-FV8
Jacques Mathieu
Alexandria, VA
(299 posts)

Registered:
09/11/2009 08:55PM

Main British Car:
1977 MGB Small Block Ford, 331 Stroker

Re: 4.6 GT V8 Modified for road & track
Posted by: MGB-FV8
Date: February 05, 2010 12:56AM

Hi Mark and WOW! I've watched the video three times; it got me a little daisy. What kind of speed did you get your car to on straight away (MPH)?


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 05, 2010 03:56AM

Johnny
Pics as requested.

Jacques
Max speed on that particular track is just over 130mph measured on sat nav. Speedo goes off the scale (140mph+)
Silverstone 2.jpg
Silverstone 1.jpg
Silverstone.jpg


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 05, 2010 04:45PM

What's been done to the engine to get you hp? If i may ask.


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 05, 2010 05:09PM

4.6 top hat linered crossbolted block, Huffaker inlet manifold/edelbrock 500 (1404). Self ported heads with stage 3 valves & 27.2cc chambers. 4.0L pistons making the compression ratio 11.04:1. Mechanical 238 cam. RV8 style single straight through silencered exhaust. Mallory magnetic dizzy.
Think thats about it.

In the process of fitting Merlin heads which have larger valves so hoping to break the 300 barrier. (currently 293bhp).

Cheers
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 07, 2010 07:50AM

Mark,

Interesting tire set up; 205 - 235. What wheels (Minilite?) and what width and off-set you runn'n front and rear?

Stock MG axle with 3.07 ratio? Quaife limited slip? Stock leaf springs or someth'n different? Any brake mods?

Thanks for suffering the questions. Love the grille . . . and the stance at speed. Too much fun!

Johnny
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