What's a decent 1/4-mile time? | MG MGB GT V8 Factory Originals Technical

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MG MGB GT V8 Factory Originals Technical - What's a decent 1/4-mile time?

Out of curiosity, I was wondering what a Rover 4.2-powered BGT might be able to do the 1/4 mile in. I only have block-hugger headers which probably cost a lot in terms of power but everything else is pretty massaged. All I could get on it rubber-wise was 195/60R15s though.

I'd take it to a drag strip and see if I could do a couple of passes but there isn't one anywhere nearby here and it's not likely I'll find the time. Just a ballpark guesstimate would be mighty interesting.

Ted

I would think mid 14's would be possible. My 302 jusr ran in the high 13's, with your tires/wheels I could probably pull mid 13's maybe a bit better. Just guesses based on my performance, but I think is reasonable..
Probably high 90's for Mph.

Larry Embrey

OH.. here is a page with my results..

http://www.embreyfamily.com/mgb/TechRoom/MYMGB302Conversion/results.htm

Larry Embrey

low 14's 100 mph. Those tires are the limiting factor, you'll have wasted an 1/8 of mile just getting traction.

Joaquin

Joaquin,
You would be surprised how much traction the car will have. I have 175/70R14's and while they broke loose on gear changes on all but one run I was able to get a smooth strong start without breaking loose..

Larry Embrey

This will betray my total ignorance of drag racing, but when you do a 1/4-mile run, at the start do you wind the car up to high rpms and dump the clutch? If so, how do you prevent the tires from breaking loose? Does this practice chew up tires and clutches, or do a few passes make no real difference? ... I'd love to try it but would hate to break the car.

Also, how do we know what redline is? On a factory V8 I think the redline was 5200 rpm but surely it's higher with a later, more massaged motor?

Bill Withum

A decent 1/4 time for a street car I would put at Mid to Hight 12's.

The G

Larry what kind of heads are you running?

The G

Larry,

Congrats on getting it up and running and to the strip. Times look good, especially considering stock suspension and street tires. I think The G has a street car named desire in mind.

George B.

What you guy's think 12's are to slow for a street car?
I think that is about good. Does Larry have a stock rear axel or just springs and shocks. I will check out his site a little later to see if it tells.

The G

My entire rear is stock, tires, axle etc. 12seconds is INCREDIBLY fast for a street car. Every 12sec car I have seen suffer drivability )lopey cams, touchy throttle, extreme tires, etc) to make the power needed to pull 12's. BUT Our MGB's with larger displacement V8's have the power to weight ratio to pull it off, the issue with a B is not power under hood, but rear suspension and tires. With a "good" set-up (Tires, traction bars etc..) I think I might be able to pull into 12's without further motor modifications, but I will have to pull a good react, be spot on my shift points and have good track conditions to get my 60ft time down in the 1.4-1.7 second range.

12sec is Decievingly fast, your talking over 105mph at track end. Lots of people will claim a 12sec street car, have them prove it to you on an established track, most will fall short. Most tweaked out street/strip mustangs are running Mid 13's, and they have all the goddies on them for power and traction, we are talking thousands in suspension and motor work.

BILL,
NO, for MOST street cars you would not rev her up and dump. that would tear tires loose bigtime. For more purpose built strip cars you would use an auto tranny and then yes rev up, but not all the way.. like 1500-3500rpm would be the rev range..

Larry Embrey

Larry, 12's is good. I think that with the right set-up and the correct gearing it should run in the mid 11's to low 12' My 2.8 Ford V6 runs consistanly high 13's this took some time to find the right jetting (for that day) and timimg. Among other things tire pressure, weight transfer (softer shocks at front) etc.
A well developed stock V8 should run in the mid 11's to mid 12's.
Mustangs Camaros etc. are heavier. The MGB weigh is about 2200+ lb with a V8 So... with the right set-up it should be faster due to the power to weight ratio.
4:11 geras with 26" sticky tires etc. it would be even faster. There are Hondas and Mazdas running in the 10's These are empty beer cans that are running with Ha ha ha GAS.
A MGB with a V8 or V6 is just cool, slow or fast it's a classic car that no other can match.

Bill Guzman

What about a 2nd gear slip with a long throw clutch and really sticky ones, then a hard right-left-right just touching the shoulders at 90? Bout a half mile with a cafe at the end!

Angus

An 11-second BV8? No way. Not in this lifetime. Maybe a car like Hans Pedersen's but even then I seriously doubt it. Just for a reality check, the 2002 BMW M5 does a quarter in 14.0 seconds when driven by a professional. And as you know, the M5 is a very, very, _very_ fast car. I'd guess a perfectly sorted BOP/R car would be in the mid-high 13s using stock tires, and even a 302 car couldn't possibly go below 13 w/o slicks and a drag-specific gearset. I mean, most of us run about 3.07 rears, street tires and even with the most incredible BOP/Rover ever built we're just not going to get anywhere near those numbers.

Terrence

I find 11's out of reach, unless the car is specifically set-up for draging and you run power adders like NOS or forced induction. It comes down to traction. The B is SO light that it hurts acceleration due to limited traction. Bill have you been able to get 26" drag slicks under stock B Bodywork?? Please let me know, I was thinking about buying a set of slicks for the days I play at the track...

Like I mentioned earlier, there is a line between enough and too much power for the chassis, I think once you get to the 200rwhp range ( a off thr hip guess number) you are at the max HP that the standard chassis can put to the ground.

Laughing gas might speed her up, the trick is again keeping it hooked up, but if you set up the WOT switch you should be able to keep her hooked and that will REALLY help ET. Gearing like you mentioned is also key. I am running 3.9 from stock B, when I go to a Ford rear I will go 3.73, that will help top end gearing and possible make 1st gear usefull especially if combined with taller tires.

Larry Embrey

Larry, 26" tires are possible if you cut the car and make it UGLY. You could use a set of Toyo R1 or Kumho Vector 700 these tires are sticky when hot. If you do get a set, get them shaved to 3/32 and run 20/24 lb cold and 26/30 hot. Fill the front shocks with ATF, this will allowed the car to raise up and transfer weight to the rear tires, install a 2x2 square tubing with clamps to the front of the springs, this will eliminate spring wound and will increase traction. If a Holley is carb is used, use the lowest number power valve and step the rear jets one number, and crank the timing right before starts to ping.
This is a small thing you can do to improve your ET at the track, and then drive the car home after you removed the traction bars.
Remember that the rear section of the B only has the floor pan and some weak braces, this allows the chassis to flex in the up, down and side ways.
This is the reason why I have not build a V8 kit; I will not build a V8 kit until I make the proper brackets to stiffen the rear of B. The GT is better in this respect but it also needs bracing.
The structure of the B starts at the jacking points forward. The rear has not have a sub frame.

A street car and a race car combination is a compromise, therefore desire results are also a comprimise.
Larry, 12's is very respectable time in street V8 MGB.
Well done!

Bill

Bill Guzman

I've driven my Mg at the track may times with the stock suspension and my 4.6L, and while the power is there, I find traction to be the limiting factor. When my car was equiped with an open rear, I could still spin my tires halfway down the track. Lower gears would definetely hurt most MG's as they're so light. No way would 11-12 seconds be possible without MAJOR mods, which by the way I'm undertaking to hopefully get into 12's. A lot of people that have never been to the track think they're cars are faster than they really are, but there is ALOT of difference between 12-13-14 second cars. For me the major problem was taking off the line. With open diff, really worn 195/R15 tires , soft shocks in front, torque bar from diff to body, stock leaf springs, and close to 300 hp and as much torque, there was no technique that helped me launch fast. High rev take offs simply break the tires loose in 1'st, 2nd and 3rd gears. Nearly bogging take offs help initially but the tires brake loose as the revs climb. The best method I found is to simply take off at less than full power thereby compromising et's. While our mg's might be able to out accelerate corvettes and porsches on the freeway, from a stand still it's pretty hard. I think it would be cool to have a site where people that have actually run their MG's at the track could post their time slips and maybe a discription of their vehicle. And I would love to hear from anyone running 11's or 12's with stock suspension :)

Joaquin

People don't realize how fast a true 13 sec car is. Back in the day I had a '69 Mustang with the 428CJ and it ran consistent low 13's. I scared defenseless passengers in that car on a daily basis. I hope my finished conversion is as fast.

Mark

Mark

Guys, with tons and tons of due respect, even thinking about getting an MG to do a quarter in 11.x seconds is proof positive that you've been breathing too much carbon monoxide. If you take a look at

http://www.syclone.freeserve.co.uk/rivals.htm

you'll see quarter times for a lot of motorcycles and cars. There are no street cars listed that can do it in under 12 seconds, only motorcycles. A 569 hp Lamborghini Diablo GT takes 12.4. A TVR Griffith 500 takes 12.9. Seen in this light, I think this thread is so much blathering (albeit pleasant blathering, don't get me wrong!).

However, it does make you realize what Larry has achieved ... pretty stunning.

Fred Testa

Nice site strange how a landrover dicovery was faster than a MGF steptronic. What do you recon a stock V8 will do it in ?
Mick

Michael Black

Has anyone used drag radials at the track (BFG drag radial seem to do ok) that might help with some of the traction problems. Bill do you have a web site? I did a search for your name and did not see a listing for a web site. Thanks.

Jim

I have to add my comments to this now. 1/4 mile times are not necessarily an accurate account of how fast a car is. Drag cars are set up much differently than street cars. There was mention of 'super cars' not being faster than 11 seconds, but you can have drag cars with less power and that are less aerodynamic beat these same cars, however top speed will most likely be different. Cars are set up much differently depending how they are going to be used. I wonder how much faster some of the cars on that list would be if a few items were changed (i.e. removing sway bars, adding drag slicks, changing shocks etc).

Zach

Zach

Good comments all around.

FRED,
Not sure about the rest of the group, but Carbon-Monoxide is to expensive, I find skipping to straight gasoline sniffing is cheaper and faster high.. :-P J/K

I have NOT broken into the 12's yet, BUT I believe the car has teh power in it now to do so, like mentioned it will come down to set-up. I need to get rid of the stock B rear, then I can start addressing tires, wheels, and traction devices.

13sec is WICKED FAST. no arguments there and a 14 vers 13 sec car is a big step.

I have me results up on my site.. Go into tech section, then my V8 conversion and there is a link... all 12 runs are listed. pay close attention to the POOR 60ft times! They need to be down under 1.8sec for a "good" launch.

Larry Embrey

Jim, my web site is www.classicconversionseng.com
Bill

Bill Guzman

Ok guys
There has been lots of talk about times etc. Yesterday I took my 75 MGB to the drags here in the small town where I live. We have to shut the airport down for a day and it’s only 1/8th of a mile but some of the times are consistent with a ¼ mile
My Rover 3.5 has been bored out +.020, Isky Racing Cam, Edelbrock Intake and Carb, block hugger headers and stock rear end with 185/75/14 tires Pirellis. Currently it is crapping out at 5000RPM. I realize that the reactions are a variable but it does give you some indication of speed with reference to the first 60ft, which ¼ mile or 1/8th mile should be a good indication. So the times from yesterday are

Reaction Time .586 60ft 2.591 MPH 67.539 ET 10.539
Reaction Time .674 60ft 2.512 MPH 67.97 ET 10.446
Reaction Time .561 60ft 2.569 MPH 67.06 ET 10.635

The last Drags where in August (car was running better) and my best times there were;
Reaction Time 1.245 60ft 2.364 MPH 71.31 ET 9.872
Reaction Time .705 60ft 2.423 MPH 71.09 ET 9.967

Bruce

Not sure how this will come out. In case it does not come out readable, they this link: http://www.embreyfamily.com/mgb/TechRoom/MYMGB302Conversion/results.htm

Run R/T 60' 330' 1/8 1/8 MPH 1000 1/4 1/4 MPH
1 0.909 2.326 6.277 9.578 70.39 13.001 16.423 62.37
2 1.167 2.436 6.291 9.482 77.59 12.590 15.944 62.11
3 0.731 2.361 6.232 9.485 74.75 12.738 16.340 56.17
4 0.941 2.482 9.331 77.68 12.596 16.047 61.77
5 0.966 2.252 6.027 9.203 76.86 12.082 15.164 65.70
6 0.659 2.373 6.271 9.841 71.00 12.890 15.208 94.79
7 0.670 2.314 6.155 9.962 62.95 13.657 16.411 85.79
8 0.568 2.337 6.083 9.159 79.75 11.781 13.989 101.81
9 0.661 2.304 9.005 82.05 11.632 13.933 97.70
10 0.739 2.290 9.018 81.75 11.622 13.874 99.89
11 0.559 2.373 6.180 9.197 82.04 11.764 13.940 102.37
12 0.744 2.425 6.111 9.095 82.78 11.645 13.825 102.25

Larry Embrey

Lets try again...
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Larry Embrey

an mg as an 11 second car? i seriously doubt that could be done. my motorcycles are 11 second vehicles and it would take a lot of work to get an mg there. my e46 m3 is a mid-13's car and it's pretty darned fast. a corvette z06 is probably only in the 12's or low 13's.

jeffnee

11's could be done, but would definitely be a track specific type vehicle, not a daily driver type. a GT would be best though as a 5-6pt roll cage is required and will take a stiffer chassis to handle the required power. I AM thinking about it. Needs to be a MG in the NHRA series...

Larry Embrey

Larry
Fibreglass bodied MG sillouette with tubular spaceframe chassis stuffed with Big Block Chevy, Chrysler or maybe Ford, 10inch minimum slicks and decent locker diff, with traction bars or similar and then you might be in business.As you say definately a race specific vehicle.

Pete

Anyone know were I can get a fiberglass sillowhettee? sounds realy expensive..

It might take less than you guys think. MG's have a big advantage of light weight. The motor I have in my car now is very tame for a 302, it would maybe get a mustang into the mid 14's, MAYBE. The thing keeping my car out of the low 13's and maybe high 12's is drivetrain/traction. I have a good half of a second to shave off in the 60ft times, typical drag calculations put each .1 saved at 60ft is roughly .5 at end of quarter. Other factors play into that as well, but that is ALLOT of time. I have 2 drag guys tutoring me right now giving me the drag info, which I then take and balance with the road handling I want out of the car. Based on the current performance we have seen, we all think high 12's is within reach after a bew rear axle and good tires/traction devices.

Larry Embrey

There's a 63 MGB in my area that runs in the 10's - best time is 10.67 @ 127mph. You can see a photo of it on Dan Master's site that I posted some time ago. This car is street driven regularly in the summer and runs a big block Chev with auto trans and tubbed rear wheel wells with very large tires.

Phil

Phil
That's one serious car!
Would imagine though it has a tendancy to go straight on when it comes to a corner due to massive weight at the front.

Pete

It's what you would cal la point and shoot car HEH point where you want to go, pull the throttle and hold on.. heh

BUT it illustrates that a B can do pull great ET's, though I think it can be done with less extreme set-up.. Time will tell.

Larry Embrey

This thread was discussed between 22/05/2002 and 09/06/2002

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