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11-30-2007
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Originally Posted by Artvonne View Post
You know, if you asked most machine shops, they wouldnt touch this with a 10 foot pole. You get heads welded and they dont heat treat them, why would you have to with a block? I never asked because I was waiting for someone else to do it
Most shops wouldn't touch it with a pole because they have a lot most sense then me. It would be best to heat-treat both heads and blocks, but the wrapping problem prevent it.
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Mark, you are truly an inspiration. But I would ask, what about internal stresses that could lead to cracking. If your not going to heat treat it, is there any way to guard against stress cracks? Shot peen or some other kind of stress relieving?
Stress relieving the block would pull all the heat treat that’s left anywhere out, and wrap everything just like re-hardening would do so I'm not going to do it. Honestly, I've just never run into any kind of problem on aluminum. Fatigue or strain cracking yes, but not stress from welding….so I’m hoping the trend continues.
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I find it all facinating what people can do to engines and get away with, welding cams and regrinding, welding cranks and regrinding, welding major castings, etc., and it holds together quite well for the most part. Heck, you even made a reference to cutting a connecting rod to change its length and welding on the small end. Yet in the aircraft field none of that would ever be allowed. You cant weld hardly anything on an airplane, and what you can weld needs a whole series of analyses done to prove its sound ie; x-rays, penetrant dyes, etc.. In fact the only two parts I know of that can be welded are the engine mount frame, and the exhaust system.
Mark, is your plan to modify the gearbox by welding rails to bolt the block to it as Goldman did? Also, have you thought of trying to shift the motor more to the left? If you sat the gearbox down in the chassis, I would think you could bring the transfer gear case over until its about up against the fender liner. Because I assume your going with some kind of crank fire ignition, you wont have the added length of the dizzys holding you from shifting to the left a bit more. But then I suppose the input shaft would become a bigger issue? You also mentioned something about changing the gear ratio in the transfer gears, and lowering the engine, or moving it further forward? Could you explain further???
Airplanes are different, they are like the medical devices I build in my day life, you have to prove that everything works, the process is in control and there are no tolerance or other variability issues that may cause a problem now or in the future. When a car engine stops running no ones life it in danger, that changes things quite a bit.
Believe it or not, I only weld as a last resort and I see no reason to weld the rails to the gearbox....at this point in the project anyway. I do need to cut and weld to the pan section on the right side but then I'd like to bolt the rails on.
I'm on the fence about direct-fire ignition but will probably do it in some form. I am moving the engine further to the left then he did I'm pretty sure which means shortening up the clutch/flywheel stuff I guess.
I've honestly only thought about it in a conceptual sort of way at this point…I looked at it in the car for a couple days, said “yup” and went on my way prepping the engine. Once the heads are on the engine it will go back in the car for a more serious look and I’ll finalize the plans. Right now I now the engine hits the frame if I go past “x” to the left (although I may cut the back of the block) and hits the shock tower if I go past “y” to the right and x and y are 1” apart without cutting the block.
I’m planning to do my input gear a bit different than goldsmith did. I’m going to add a bearing in the transfer cover for additional support. I’m hoping to also put the existing bearing back in it’s original location to keep the input shaft supported the way it was designed to be supported.
For the gear ratio, I am planning to install the trans input gear up on the clutch shaft and the clutch gear down on the tran. That will change the ratio by 23% putting 1st gear about ¾ of the way to the current 2nd gear and raising the top speed at redline to about 180 mph. I think this engine will have as much or more torque as the supercharged v8 and 1st gear was just useless with that much torque. This should be a nice set-up.
The plan is to cut hubs of the gears out and a new larger ID spline pattern into them on the wire EDM. Then bolt them on to new hubs that fit the splines, off-sets and bearing for there new homes. That will mean moving the idler gear, so if there is also an opportunity to lower the engine a bit, it won’t really be a lot more work if there is a significant gain….and I don’t think there is after having a good look at it.
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