308 V12 conversion begins

The stud and steel nut on top are 11mm dia and also 11mm long, which on steel should mean the bolt will break before the threads strip. So that’s good.

Down in the aluminum the diameter is 14mm and the length is 28mm giving about 3 times the bite in the aluminum....which is good, but I'm not convinced its enough to hold the bolt to failure with the reduced strength after welding. My plan is to simply put more threads on the studs, like 40% more to match the lose of material strength.

Now you went and ruined the big surprise

 

That's right. A course thread has a smaller root or minimum diameter so there is more metal in the thread itself.

On the OEM stud the nut end is a M11-1.0 and the block end is a M14-1.5. A 1.5 has 50% more aluniumum in the thread than a 1.0 would. I should have included that in my quick calc...but I just forgot. I think (I have to go look it up) that a M14-1.5 is actually the metric standard fine thread and M14-2.0 is course. I could make that change too, it weakens the stud a bit, but in the 14mm section so it's realy not a concern.

 

I'll finally be ready to get started on that next week I'm hoping. I need to get the decks cleaned off and the head alignment pins in the block first so I know where the heads actually go. Then I’m ready for the timing chain issue....expect to see the welder out again.....

 

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.

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.

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.

 

You're right that the car would definitely want to go faster than 180 with the hp it will have. The problem is that without making new gear sets or adding a 6th gear somehow I get stuck with a 1st gear that is just too high around town or a top gear that is too low for peak performance. I just don’t see any easy way to fix it.

 

Doh!

You know, I know better than to weld without a jig or at least clamping it down to the welding table (mine is 1 1/4" think steel with 1/2-13 bolts hole ever 3") but I didn't do it.

The next one is going to come out so much better......

 

Today’s adventures

A couple more emails with the VEMS ecu guy and that looks like a done deal. It does quite a bit more than can easily be found on their web site and for the price it’s a heck of a bargain.

I confirmed that M14-2 is standard metric course and got taps order. That will add a good amount of strength to the threads over the stock M14-1.5 in the now softer than stock block. Of course this means I’m making my own head studs….since I have so much time on my hands and all…..

After a little digging, I think 4150 chrome-moly steel is what I’ll go with for the new studs unless someone has another suggestion???

Tomorrow – WELDING.

 

It’s a case of the right decision for the wrong reason then….the stroke is going to stay 78mm. Welding the crank is not recommended, I can’t afford a new billet crank and don’t have time to make it myself, so stock it is….for now anyway.

I’m trying to get he bore up to 86.5mm to get me 5.5 liter, but 85mm and 5.3 liter will do if I get scarred when I get the liners in my hands.

Just a quick run through the numbers says I’d still need to let the engine spin to 8500 to hit 200mph, and not just spin, but actually make hp….I don’t know. It’s really just theoretical anyway because around here they arrest you if they catch you doing anything like that on the street and the car is not going to the track. I guess I could set the redline in the ECU at 8500 and say it should do 200mph and that’s that.

This is a street car that will occasionally go to the autocross, getting to 80-85 mph quickly is all I need, anything more is gravy.

I’m guessing it will be about 3100 lb. ‘,ve got the light gto/euro bumpers and the exhaust will probably save some weight, no spare, aluminum radiator, aluminum shocks, I may end up A/C less if I can’t find a place for the compressor, but the engine weights 100lb ish more than stock.

There honestly won’t be any serious weight reduction effort in this project for time and budget reasons. That will come when my car budget recovers a bit and I’m ready to paint. I’m looking at a seat change, new rear deck lid (that will happen now if I need more room under it)

 

Another tough day with the welder....Last time it was the power line and the gas line today it was the water return twice. Welding to get the 348 liners to work slowed the whole process down a bit too. Another day I guess. I’m starting to remember why I don’t like welding.

While it was hot I extracted 9 or the 10 remaining studs. The 10th snapped off at the base of the threads on top. Sean suggested a CNC tool holder collet so I'll try that on the last one.

 

That I will have

 

Thanks Steve, I'll look into both places.