LS1 into a 1972 MGB GT
01-18-2010, 11:14 AM
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Touchdown! 
The car hit the ground for the first time on the new suspension yesterday. The front suspension used to use a lever arm shock as the upper mount, now it's basically a Miata setup. The rear used to be leaf sprung with lever arm shocks, now it's a three-link coilover. There's a lot of work in this setup, so there was a lot of rejoicing when the wheels touched down.
I have to move the rear shock mounts for a bit more droop travel and the fenders need a lot of modification, but this is a big step.
An hour later, I had the car back up in the air and the engine/transmission went in. It's in the final location now, so I'm building motor mounts. Clearance is tight - there's 1/4" between the steering rack crossmember and the oil pan. The biggest problem is going to be the steering column. It's going to have to be rerouted, and the exhaust on the driver's side will have to be a custom-built setup to go around the column.
Soon I'll be working on the stuff that actually makes noise. Can't wait!
01-26-2010, 01:53 PM
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I've been building motor mounts - like a ship in a bottle, they're kind of hard to get to! - and a transmission mount. The transmission mount is removable so I can actually get the engine in and out of this thing. The motor mount on the driver's side is close enough to the steering column that I'll have to weld one of the universal joints to the shaft, as the bolt that locks them together hits the mount. Not a big problem, and I'll be able to explain that better once I have the parts out and ready to show off.
The engine is now self-supporting and in place. So it's time to start packaging everything around it.
The MG originally had unboosted brakes and drums in the rear. I want a power setup to help slow the car down and to deal with the greater pressure required for my 4-wheel discs. The layout of the stock brake system put the master cylinder above the pedals facing backwards. This pretty much made a booster out of the question. So I found a pedal box and booster out of a later 1975 MGB, which puts the master in front of the pedals and has a booster-friendly pedal ratio. After a lot of math and consideration of options, I decided to adapt the Miata booster and master cylinder to the MG pedal box. This gives me a choice of two master cylinder sizes and three levels of power assist for fine-tuning. Packaging is tight, though. I have only about 1/4" between my booster and the fitting for the PCV system on the driver's side valve cover. My 1998 engine has a different design here, the later ones would fit fine. So I'll reshape that a bit and make it work.
Another challenge was the steering column. The stock MG steering column has a big u-joint right after it passes through the firewall, and the joint interferes with the head fairly dramatically. So this has to change.
The MG column is also pretty large in diameter, much bigger than the fittings on the Miata rack. Just for fun, I measured up a Miata column. And I got super-lucky. It's the perfect length. Even the mounting plate where it bolts to the under-dash support is in the same place. And the u-joint between the two sections is slightly higher up. I'm still shaking my head about this one. As an added bonus, the column stalks will give me switches for the cruise control, which I'm hoping to install eventually. The new column runs just low enough that I'll be able to put it between the headers and the block. I'll weld up the brackets for the column tomorrow and I'll have steering.
The engine is now self-supporting and in place. So it's time to start packaging everything around it.
The MG originally had unboosted brakes and drums in the rear. I want a power setup to help slow the car down and to deal with the greater pressure required for my 4-wheel discs. The layout of the stock brake system put the master cylinder above the pedals facing backwards. This pretty much made a booster out of the question. So I found a pedal box and booster out of a later 1975 MGB, which puts the master in front of the pedals and has a booster-friendly pedal ratio. After a lot of math and consideration of options, I decided to adapt the Miata booster and master cylinder to the MG pedal box. This gives me a choice of two master cylinder sizes and three levels of power assist for fine-tuning. Packaging is tight, though. I have only about 1/4" between my booster and the fitting for the PCV system on the driver's side valve cover. My 1998 engine has a different design here, the later ones would fit fine. So I'll reshape that a bit and make it work.
Another challenge was the steering column. The stock MG steering column has a big u-joint right after it passes through the firewall, and the joint interferes with the head fairly dramatically. So this has to change.
The MG column is also pretty large in diameter, much bigger than the fittings on the Miata rack. Just for fun, I measured up a Miata column. And I got super-lucky. It's the perfect length. Even the mounting plate where it bolts to the under-dash support is in the same place. And the u-joint between the two sections is slightly higher up. I'm still shaking my head about this one. As an added bonus, the column stalks will give me switches for the cruise control, which I'm hoping to install eventually. The new column runs just low enough that I'll be able to put it between the headers and the block. I'll weld up the brackets for the column tomorrow and I'll have steering.
01-26-2010, 02:11 PM
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Thanks! I'm expecting around 2500-2600 lbs based on the typical weight of a Miata with this drivetrain and the starting point of the car. It's going to be a bit heavier than necessary because of a bunch of planned sound deadening material to make it a nice highway cruiser.
I forgot to mention that I've been researching mufflers. I don't have a lot of room (that's getting to be a consistent story) and I'm thinking a single Flowmaster 50 SUV with 3" piping will have to do the job. I'm still looking at sizes, hoping I can manage to squeeze in duals if I move the fuel tank a bit to the side.
I forgot to mention that I've been researching mufflers. I don't have a lot of room (that's getting to be a consistent story) and I'm thinking a single Flowmaster 50 SUV with 3" piping will have to do the job. I'm still looking at sizes, hoping I can manage to squeeze in duals if I move the fuel tank a bit to the side.
01-26-2010, 06:39 PM
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thats ****** killer!!
cant wait to see it when its done..its going to be a monster with the power to weight..the motor make est 400-450 crank hp? in a 2500-2600lb car...she shall fly!!!
cant wait to see it when its done..its going to be a monster with the power to weight..the motor make est 400-450 crank hp? in a 2500-2600lb car...she shall fly!!!
01-26-2010, 07:39 PM
#66
Each time I look at this I feel like I have had so much room to work with on all my previous projects. Sadly most that see this car on the street will never understand your challenges in getting it moving under V8 power. 
You have come a long ways, keep up the good work!
You have come a long ways, keep up the good work!
01-27-2010, 05:18 PM
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The motor is a pretty standard LS1 - it's just got a bit of headwork, springs and a mild cam. I would say that 450 hp is pushing the estimates pretty high. Even if it's at 350, I think it should be a pretty quick little guy.
I'd be happy if the car was judged on the final result, not on the difficulty in getting there. Really, I'm building this for me (and my wife), so it doesn't really matter what anybody else thinks.
I'd be happy if the car was judged on the final result, not on the difficulty in getting there. Really, I'm building this for me (and my wife), so it doesn't really matter what anybody else thinks.
01-28-2010, 02:39 PM
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Well, it's not done yet and there's still a long way to go But it will be! I had to take some time out for other things, but now it's full steam ahead on the little black car. I'm hoping to have it out and running around this summer.
I didn't post pictures, but the shock towers are tied into the unibody now. I'm going to lift the engine a bit so I can tack the last part of the last motor mount in place - the steering rack u-joint goes right through the middle of it, naturally - and then I'll drop the whole thing on to the ground with the engine and transmission inside. There's no real reason to do that other than the fact that I want to move the car a bit so I can do some work on garage organization, but it's going to be super-cool to see regardless.
But it will be! I had to take some time out for other things, but now it's full steam ahead on the little black car. I'm hoping to have it out and running around this summer.I didn't post pictures, but the shock towers are tied into the unibody now. I'm going to lift the engine a bit so I can tack the last part of the last motor mount in place - the steering rack u-joint goes right through the middle of it, naturally - and then I'll drop the whole thing on to the ground with the engine and transmission inside. There's no real reason to do that other than the fact that I want to move the car a bit so I can do some work on garage organization, but it's going to be super-cool to see regardless.
01-28-2010, 04:26 PM
#72
I still think you're shooting a bit heavy on your projected weight. When you have the engine and trans in while the organizing is goin on, throw that beast on a set of corner scales and tell us what you get.
01-31-2010, 01:09 PM
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Wow. Joker, my weight estimate was based on two things: the published curb weight on the stock MGB GT is 2401 lbs, and a Miata gains about 200 lbs with an LS1 conversion. But you're right, it was a perfect opportunity to check. And I had a hard time believing the result.
Wow.
Now, that's a car with no fluids (just filling the gas tank will add at least 60 lbs, and I always weigh with a full tank), no cooling system, no interior and no exhaust. Heck, there wasn't even a steering column, battery (a 27 lb Optima) or spare tire in it and I've taken the (fairly light) front bumper off. But I did have a box full of wiring from the Camaro in the car (26 lbs!) and there was a Miata seat stuck inside.
It's possible there's as much as 500 lbs of weight left to go into the car. But it looks like I was pessimistic on my final weight estimate. I'm going to drop it to 2400 lbs.
I figure the new front suspension is quite a bit lighter than before, and there's no question the Miata wheels are lighter than the MG stuff. The weight from the fuel and battery will go on the rear wheels so the balance will improve. A full tank of gas and the battery will actually give it 50:50 weight distribution as it sits.
Wow.
Now, that's a car with no fluids (just filling the gas tank will add at least 60 lbs, and I always weigh with a full tank), no cooling system, no interior and no exhaust. Heck, there wasn't even a steering column, battery (a 27 lb Optima) or spare tire in it and I've taken the (fairly light) front bumper off. But I did have a box full of wiring from the Camaro in the car (26 lbs!) and there was a Miata seat stuck inside.
It's possible there's as much as 500 lbs of weight left to go into the car. But it looks like I was pessimistic on my final weight estimate. I'm going to drop it to 2400 lbs.
I figure the new front suspension is quite a bit lighter than before, and there's no question the Miata wheels are lighter than the MG stuff. The weight from the fuel and battery will go on the rear wheels so the balance will improve. A full tank of gas and the battery will actually give it 50:50 weight distribution as it sits.
02-09-2010, 11:04 PM
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Well, I've got steering now. I modified the Miata column to clear the motor mount - that's some tight clearance there - and I just have to add the right bracket for the top of the column under the dash. I stuck a seat and the pedals in the car to get a feel for the ergonomics, and it's pretty darn good. This just might work!
I've been looking at exhausts. If I move the gas tank over 3" - a matter of drilling a few holes - I can fit one of the typical 5x10x14 mufflers on each side. Just. Good, that means I can run a 2.5" dual exhaust system instead of a single big pipe.
I've been looking at exhausts. If I move the gas tank over 3" - a matter of drilling a few holes - I can fit one of the typical 5x10x14 mufflers on each side. Just. Good, that means I can run a 2.5" dual exhaust system instead of a single big pipe.
02-17-2010, 11:18 AM
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Suspension Nice build so far, I started to do a Buick/Olds/Rover v8 conversion several years back in a 79 B. Life got in the way and got rid of the car. Still have the engines laying around. What are you doing for front suspension? I saw in the back of "Grassroots Motorsports" magazine a really nice bolt-in front end that I thought about using.
My current project is a 5.3 into a 944 Porsche.
Regards
Mark
My current project is a 5.3 into a 944 Porsche.
Regards
Mark
02-17-2010, 11:57 AM
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Mark, I have a Buick engine sitting in the garage as well. I drove a Buick-powered MGB a while back and that's actually what got me started on this project. It was more noise than performance, though - I think a stock 1.6 Miata would have taken it in a drag race. So I went with something burlier
Fast Cars Inc. makes a nice bolt-in suspension upgrade, but I chose to stay away from it. First, it's expensive. It would also require me to stick with the MG bolt pattern, heavy parts and narrow track. I built a complete front suspension based on Miata parts instead. Took longer, but I'll end up with a better handling car and more parts interchange with my current stable.
Update coming later today...
Fast Cars Inc. makes a nice bolt-in suspension upgrade, but I chose to stay away from it. First, it's expensive. It would also require me to stick with the MG bolt pattern, heavy parts and narrow track. I built a complete front suspension based on Miata parts instead. Took longer, but I'll end up with a better handling car and more parts interchange with my current stable.
Update coming later today...
Last edited by Keith Tanner; 02-17-2010 at 12:07 PM.
02-17-2010, 12:21 PM
#78
Even if your car gains weight, you will most likely remain well under 2500 lbs! Maybe I need to start looking at lighter cars...
I'm impatiently awaiting the promised updates.
02-17-2010, 06:35 PM
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Not sure why you're having trouble seeing the pics, Merv. Does www.slowcarfast.com/MG work for you? Not that it's very attractive at this point, the car seems to be a combination of Aqua (ie turquoise), black and crust
So, I've been dreading the wiring. I've wired cars from scratch (including one with EFI and distributorless ignition) and I've modified stock wiring harnesses. I've not enjoyed it much. It's sticky work, the connectors are a pain in the butt and in the Miata, the engine harness is integrated into the rest of the car so you're chasing wires into the weirdest little sub-harnesses. I was considering a Painless setup simply to save myself the hassle. But I wasn't feeling like crawling around in the car and screwing around with metal, so I figured I'd at least look at how the GM setup would go.
Wow, that was easy.
I put together a spreadsheet of all the wires from the 1998 Camaro PCM thanks to excellent documentation on LS2.com and LT1.com, then went through and identified what I don't need. No EGR, evap, VATS, rear O2 sensors or fuel tank pressure testing - I'll turn that stuff off with HPTuners. The PCM connector is really easy to pop wires out of, and I just chased them through the harness and eliminated what I don't need. After a couple of hours of fairly relaxed work I had it done. There are a couple of flying leads for things like the tach and speedometer, but overall it was really easy. Note the fiendishly complex Lucas-equipped V12 Jaguar for inspiration.
When I laid it out on the engine, I also discovered that the best place for the enormous 1998 PCM was actually very close to the location used in the Camaro - so my wiring lengths are basically perfect. The PCM only barely fits in this location but that's par for the course with this build!
I'm pretty jazzed about this. It wasn't all that much work (not even sticky, GM uses about 1/50th as much electrical tape as Mazda does) and I feel like I've conquered a big obstacle. In fact, once I get the fuel plumbed and the various loose wires sorted out, I could probably fire up the engine. Wow. Then it's just a driveshaft and brake plumbing, and I could drive it. None of that is difficult work, really, and I'm just waiting for one fuel part to come in before that's done.
I've also been looking at speedometer options. I want to keep the cool old Smiths look of the gauges. Turns out there's an electronic version of a Smiths speedo so I don't have to resort to one of those cable adapters run by an electric motor. So there's that sorted, hopefully.
My brother in law is building a rockcrawler with an iron-block 6.0, and he's challenged me to a race when we're done. I think it might come down to the course we use...
So, I've been dreading the wiring. I've wired cars from scratch (including one with EFI and distributorless ignition) and I've modified stock wiring harnesses. I've not enjoyed it much. It's sticky work, the connectors are a pain in the butt and in the Miata, the engine harness is integrated into the rest of the car so you're chasing wires into the weirdest little sub-harnesses. I was considering a Painless setup simply to save myself the hassle. But I wasn't feeling like crawling around in the car and screwing around with metal, so I figured I'd at least look at how the GM setup would go.
Wow, that was easy.
I put together a spreadsheet of all the wires from the 1998 Camaro PCM thanks to excellent documentation on LS2.com and LT1.com, then went through and identified what I don't need. No EGR, evap, VATS, rear O2 sensors or fuel tank pressure testing - I'll turn that stuff off with HPTuners. The PCM connector is really easy to pop wires out of, and I just chased them through the harness and eliminated what I don't need. After a couple of hours of fairly relaxed work I had it done. There are a couple of flying leads for things like the tach and speedometer, but overall it was really easy. Note the fiendishly complex Lucas-equipped V12 Jaguar for inspiration.
When I laid it out on the engine, I also discovered that the best place for the enormous 1998 PCM was actually very close to the location used in the Camaro - so my wiring lengths are basically perfect. The PCM only barely fits in this location but that's par for the course with this build!
I'm pretty jazzed about this. It wasn't all that much work (not even sticky, GM uses about 1/50th as much electrical tape as Mazda does) and I feel like I've conquered a big obstacle. In fact, once I get the fuel plumbed and the various loose wires sorted out, I could probably fire up the engine. Wow. Then it's just a driveshaft and brake plumbing, and I could drive it. None of that is difficult work, really, and I'm just waiting for one fuel part to come in before that's done.
I've also been looking at speedometer options. I want to keep the cool old Smiths look of the gauges. Turns out there's an electronic version of a Smiths speedo so I don't have to resort to one of those cable adapters run by an electric motor. So there's that sorted, hopefully.
My brother in law is building a rockcrawler with an iron-block 6.0, and he's challenged me to a race when we're done. I think it might come down to the course we use...