The Engine Fits Under the Bodywork!

This weekend’s project was to re-attach the floor so that I can take measurements under the engine and bellhousing.  I mounted the engine as high as possible while still fitting under the existing bodywork to give me the most possible ground clearance.  That is the opposite of what you normally want to do in a race car where you’re trying to lower the center of gravity, but that’s not my primary concern at this point.  The current plan is to keep costs down by using a wet sump oil system (rather than an expensive and cumbersome dry sump system) and a Corvette C5 transaxle (rather than a big-buck racing transaxle) while not modifying the upper bodywork and minimizing the amount of cutting to the floor.

Figure 1: The floor is reattached.

With the floor in place, I was hoping to be able to measure under the block for the oil pan.  One nice thing about a mid-engine layout is that there isn’t a crossmember to deal with so I have a lot of freedom with regards to the sump design… front, rear, whatever.  But I ran into a snag in that my prototype wooden front engine plate has started to sag.  There’s a noticeable deflection between the back of the tub and the front of the engine block that is causing the floor to not fit properly.  So I’m going to have to redo at least a part of that and get everything lined up before I can start taking the final measurements and picking an oil pan.

Figure 2: Long block in place without an oil pan.  If I did everything correctly, there should be about 5.5" clearance at the front of the engine and a little less in back.  I need to solve the aforementioned mounting problem to get the final numbers.

Just for fun, I went ahead and set the rest of the bodywork in place to check clearances on top of the engine.  I’m withholding final judgement until I get the front engine mounts straitened out, but so far everything looks OK.  The truck intake manifold is definitely going to need to be replaced by a lower car manifold and there might be some interference with the oil filler on top of the valve cover.  I was already planning on relocating the ignition coils to the side of the engine so I’ll probably look for a set of nice smooth topped aftermarket valve covers.

Figure 3: Bodywork sitting roughly in-place.  The engine basically fits so I don't see any showstoppers as of yet.

The (non) structural integrity of plywood

So it turns out that I may have overestimated the structural integrity of plywood.

I made the prototype engine mounting plates out of plywood because it was cheap and easy to cut.  And it was good for test fitting and verifying my dimensions, but it was not strong enough to actually hold up the engine.  Once I got everything bolted together and tried to jack up the car to remove the dolly from under the engine, the two piece mid-plate between the engine and bellhousing creaked and flexed in a major way.  It was not going to hold.

So then I had to come up with a Plan B.  Eventually that materialized as two 3" x 1.25" x 24" aluminum bars.  One bar runs horizontally across the top of the bellhousing where it bolts to the top center hole in the block and the top hole on each side of the bellhousing.  The second bar also runs horizontally and bolts to the two lower holes on the back of the engine and the middle holes on each side of the bellhousing.  With those bars in place and the wooden front plate still bolted to the tub, I put a jack under the transaxle case and started jacking up the back of the car.  There were a couple of groans from the front plate at first, but it held and I was able to jack the car up high enough to get the engine dolly out.  Success!  The two halves of the car were joined again and it would roll.  

Figure 1: Engine-to-bellhousing mating with 1.25" thick aluminum bars.  

It was a nice day so I rolled the car out and washed it.

Here is a close up of the engine, bellhousing and the rear of the car.

Figure 2: Engine, bellhousing and transaxle.  Notice how there is no rear subframe, the rear suspension bolts directly to the bellhousing and the transaxle case.

Now that that's sorted, it is time to reattach the bodywork to measure how much clearance there is for all of the peripheral systems and probably a different transaxle.