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MG MGB GT V8 Factory Originals Technical - strip results
|Got out to the Edgewater British Car day Sunday, decent show as always. While there I made a few passes down the strip just to see what would happen.|
It was immediately obvious that I'm no drag racer, as I proceeded to do just about everything wrong that was possible, but I soldiered on resolutely for six back-to-back passes in an attempt to get a good start and some reasonable indication of what the car could do.
I should have quit after the 5th pass. Or at least stopped to cool off, but "just one more and then I'll quit" got me and I noticed things weren't quite right after that last pass. Skipping the gory details, it appears I blew a head gasket and possibly a rear freeze plug. Which is no surprise to anyone here, right? Still, how many people would have ever thought I could drive that car for almost a year and then run it that hard on the strip with that much boost before blowing a gasket? Maybe I'll just 'o' ring the heads and put it back that way, it depends on how the piston tops look.
And the strip results you ask? I'm embarrased. They were putting the 1/8 mile times on the board and I shut down early on every single run in spite of knowing that. My best time, with a reaction time of 1.388 was a 14.194, with my speed dropping from 81.90 at the 1/8 mile to 78.21 at the quarter. But I'll give you the other numbers and maybe someone can do something useful with them. I'd love to see some HP estimates based on the intermediate numbers.
The 60' time was 2.335 and the 330' time was 6.050, which I presume indicates the wheelspin up until the tires grabbed in 3rd, causing the engine to bog somewhat.
Then things get interesting as the time from 330' to 1/8 mile is just 3.009 seconds and from 1/8 mile to 1000' is 2.579 as this is where the power was getting to the ground and before I shut down.The times are 9.059 and 11.638 respectively.
Obviously with only a slightly better reaction time I'd have been in the 13 second bracket. (I did redlight on one run, R/T is .255 but then just poked down the track instead of trying to see how fast I could go. My fastest R/T without redlighting was a .642 so if I take the best numbers overall I would use the .565 between r/t and 60', the 3.715 between 60' and 330', then 3.09, 2.579, and 2.556 from the best run and the potential ET would be 13.147, which with a full run and a little less wheelspin would make a 12 second run look possible.
But what I actually got was a 14. Like I said, I'm no drag racer.
|dude, 13.1 is movin!! That would be faster than I have run so far. My best on ym 302 was 13.8. lots of wheels spin in all gears, but not much could to about it with a stock rear end.. I bet you are 300+hp to rear wheels.. Can't complain about that!!!|
Though it is about time to unleash my secret weapon heh Tonight hope to test 1st time, then got track day tomorrow, big 300+ car Pony trails run with the regional mustang clubs... should be exhausting next day or two...
|Jim not bad for a begining of a drag racing career.|
Please note that if you O ring the heads your CR will go up which means.....trouble with high boost.
Stock head gskets are good for 5 to 7 lb of boost
working at the moment with a roots blower for the V6 and appears that 7 lb is the max with a stock engine which is not bad, in fact that is really good.
You may consider the copper gaskets, lots of $$
|Hunh?!? The only way the CR would increase is if the compressed head gasket thickness is eliminated from the stack. Using a stainless steel wire ring with a copper head gasket of the proper thickness would keep everything about the same.|
The main thing is you were having a blast!
If you want to guestimate horsepower you really need a few full passes. No letting up before the finish line. The MPH trap speed tells a lot about the HP you are making. The 60 foot time is all-telling when it comes to how hard your car is launching & if it is hooking up. Your reaction time does not add to you E.T. so no fare subtracting it out. :)
I used Quarter, Jr. and several E.T. slips to figure out the HP on my Camaro. It requires that you input some vehicle info & weather info if avail. Also, altitude of the track is factored in.
Sounds good for the 1st time to the track.
Your main problem is hooking up as I read it. What tires are you running and at what pressure? At what RPM did you launch? Did you vary the launch RPM much for those differences in the 60 ft times?
I'm hoping to get to the track this summer with mine I'll give you a comparison.
|Michael S. Domanowski|
|Hey guys! David Kirkman, Pete Mantell, and I am currently working on British V8 2005, which will be held in June of 2005....we hae a "gentlemen's agreement" with the Wabash Valley Dragway .. an 1/8 mile strip .. for its availability to our participants on at least one day at a very reasonable price...plus...the strip is only a stone's throw from the host hotel! ... We are also looking into renting a nearby road course for a day (and possibly sharing it with the local Mustang/Corvette/Porsche club(s) to keep costs down)....Stay tuned for more info and get practiced to keep you reaction time LOW!|
1974.5 MGB/GT 3.9l V8
I could really have a blast with those 'other car' guys on a road coarse. That is, after all the entire emphasis of the totality of my fast car experience up to this point. In other words, that's what the car was built for, and that's how I learned to drive.
Thanks to all for the words of encouragement. I don't think I'll make a career of drag racing, but I may still give it a go every now and then. So how's the timing work Carl? If r/t doesn't affect E/T a racer could have a faster e/t and a higher top speed and lose the race? Does that mean that my theoretical e/t where I added up all the times would really be less because I added the r/t in to get the total? That would mean if I'd gotten one good run the car could have done a 12.5???! Now I really do feel incompetent!
A little more info on O-ringing the heads please, how exactly does that work? Cut a groove in the heads and put a wire in it, but wouldn't it leak at the ends? and how do you get the wires to stay put as the head goes on? And are copper gaskets even available for these heads? I think the only reason I was able to handle the boost I was running for as long as I did was because of using the 6 bolt heads. The intercooler may have helped too.
Mike, I'm running -OLD- Goodrich T/A's that are hard and about threadbare. Figured I'd burn them up rather than new ones. They're 265/50-14. The car did not hook up well under full throttle clutch dumps. No wheel hop, but I suspect I'd get better runs using a hard 'street launch' (minimizing tire spin) at less than full throttle. I didn't try that but I certainly should have, as I've practiced it almost daily. Breaking the tires loose and holding it just below the rev limiter may be fun, but it makes more smoke than speed. I wasn't watching the engine speed at launch but I did play with it a bit. Some launches were nothing but smoke (most) one or two bogged because I forgot to give it the gas before dropping the clutch, and on one I accidentally got it in 3rd and killed the engine. No happy medium there anywhere. So that's how a normally good driver manages to get a best of 14 seconds out of a 12 second car I suppose. I'd be way embarrased to say what my slowest time was.
|There's two ways to do it. Machine an o-ring wire groove in the head such that somewhere between 5 and 10 thou of the wire is above the surface. The wire will be somewhere on the order or 40 thou diameter. Cut and dress the ends of the wire square and tap the wire into the groove with the ends butting like a piston ring that's too tight. It should stay put. Cut a "receiver" groove in the block to receive the deformed soft copper gasket. This isn't too good on the street even if Hylomar is used but is good on the race track. Another way is to use a good composite gasket like Felpro and make sure the metal o-ring is such that it compresses the gasket behind the fire ring. No receiver groove in the block should be necessary.|
One thing to do when you tear down your engine is to mike the gasket to see if you had equal clamping all around. You might not need to o-ring at all.
|Thanks. I ran a compression test and got rather odd results as follows: 1-112, 3-95, 5-112, 7-100, 2-107, 4-114, 6-123, 8-105. My oil can is on loan so I'll run the second test tomorrow.|
Clearly #6 is about where it should be and there is a problem with #3, but for what is a new, low mileage motor all that scatter in the other holes surprises me. I really expected to see around 125-135 in all but one and a really low number there like 45 or so.
I'll do the oil test before I tear it down, and it could be that I was blowing out the head gasket in several places I guess. Doesn't seem likely, but it would indicate a rather well balanced output if so.
Sorry to hear about your problems. At least you have now run the car. I bet no matter what, alot of fun was had! Hope getting it home was not too much of a hassel.
|BMC Brian McCullough|
|these car do NOT launch well, unless you tub the rear and put some big slicks and upgraded rear suspen you are not going to see the low 60ft like a mustang etc.. They are just not made for that. I think the best I got was a 2.2 one time only.. she was squeelin and graoning, but stayed connected. Jim, if you cross 12seconds that means you have well over 300hp at the crank. I was running 13.8 @ 102 with my motor with a mild RV cam in it which is all torque.. and that was launching in 2nd and usgin 5th @ 1000ft due to rear end gearing..|
Keep at it man!!!
|When using O rings the thickness is decrease and CR increase a bit. Yes, if using a copper gasket with the same thickness no CR change will occur. |
I use O-rings like a Cummings diesel, the final clearance is ZERO. Cylinder bore is groove, water ports are also groove, in short everything that the regular gasket seals, is groove for O rings.
My 1.6 liter twin cam is O ring and runs a healthy 13:1 CR Not a street car.
|Jim, unless you've got the blower pulled off the engine, it may be screwing around with your compression results. Even if it's turning with the engine, you may be getting hindered airflow at cranking speeds since it's a positive displacement pump.|
Just a thought.
|I just looked back at my results. Jim, you and I would be VERY close!! Your numbers are all right in the same ballpark as mine. within .10's THat tells me you have a nice healthy motor running there.. I am a new racer too, only made 14 total runs, but man is it a blast!!!|
I am already dreaming about a MGB GT that will be 100% drag car. 351EFI based, who knows from there..
|O-ringing the heads vs the block?|
Round here I am used to seeing the block receive the o-ring. I can't see why either way wouldn't work just fine. I can see having a receiver groove opposite the 0-ring would provide ultimate sealing. A blower engine definitely needs extra sealing.
Here's some links that can explain it much better than I can. Besides, I type MUCH slower than I drive. :)
This thread was discussed between 16/07/2003 and 19/07/2003
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