LS1 Conversion, A Retrospective Build Thread Options

[andys]

Here's the start of a retrospective build thread of my LS1 conversion. It took a few years to get it done mostly due to not wanting to be a slave to the project, and work on it for the enjoyment; and of course when family obligations allowed......teen daughter and high maintenance wife (IMG:style_emoticons/default/biggrin.gif)

What I started with was a local orignal owner '75 2.0 with 139K miles. The original owner "drove the heck out of it" until something died in the electrical system and he parked it in the garage for 14 years, as evidenced by the renewal tags. Only body damage was when he submarined the rear of a Mustang and creased the hood and flattened the left signal light pod. Otherwise, it was a good condition rust free (SoCal) car.

Brief specs are: '01 LS1 Z28 motor, Audi 01E 6 speed tranaxle, 911 front suspension, custom made rear trailing arms, Koni shocks, 993 wheels, and AC.

Below, are photos of what I started with, and what I ended-up with. I'll do my best to re-trace the build process, so if you have any questions along the way, please ask.

BTW, how does one place text between photos in the same post?

Andys

[andys]

As the cooling system is a crucial part of a V8 conversion, I wanted to be sure to apply good practices for both performance and reliability. I first set out to configure the layout. As such, I decided on thru hood venting rather than the traditional thru fender venting. What I don't care much for with the thru fender venting, is that it creates a big under hood hot box. The thru hood venting, with appropriate ducting, allows the heat to rise naturally thru the opening which is especially important when sitting still in traffic. Down side of thru hood venting is of course it's affect on the car's styling. Enough pontification; lets build a cooling system!

I started with an aluminum radiator from AFCO; P/N 80133N which is an ASA racing radiator, dual pass, cap delete, 27 1/2 x 16 x 3. I see now that Summit sells them, though it's about $100.00 more than I paid a few years ago when I bought directly from AFCO. I'm going to gush a bit about how great these guys at AFCO are to deal with. Again, your typical Mid-Western stock car supplier/manufacturer that is a joy to work with...great attitude, etc. Anyway, the radiator size works out well in the 914; all that was needed was to tip it slightly forward, and it fit.

First I cut an opening in the front bulkhead, and re-enforced the center rib with a formed piece of channel to help stiffen the structure. I then determined the most suitable position for the radiator and went about designing a mounting scheme. I did what I've done on race cars, which is to build a U shaped channel lined with foam into which the radiator gets inserted into. This avoids any hard mounting, and completely shock mounts and isolates the radiator. I always cringe when I see folks hard mount radiators. There are of course other ways to shock mount, but this is how I like to do it. I made the U shaped channel out of aluminum with tabs in strategic locations for mounting. For the mounting points, I also shock mounted this structure to the chassis with two rubber isolators on the bottom, and two rubbber grommet mounts on the top. I used two Zirgo 10" puller fans and mounted them to a shroud. I also made some silicone rubber flaps to pass additional air at higher speeds thru the shroud as well. The shroud bolts to the structure.

For the ducting, I made some sheet aluminum ducts both front and back that mount to the radiator U structure, but do not fasten to the bulkhead, but stop short with foam gasketing to make the final seal. For the exit side, I made a duct that turns upwards. A foam gasket seals the gap between it and the hood.

The hood vent piece (diffuser) was designed with the help of an Art Center College of Design student, as I have no styling talent what so ever. I made a foam model which I covered with fiberglass and filled and sanded smooth. The size of the opening in the hood is 1.7 times the inlet side to help create the requisite pressure differential to draw the air out (with the help of the vent/diffuser). This diffuser sandwiches a rubber gasket to protect the paint, and is fastened to the hood by stailness button head screws from the underside (I bonded threaded inserts into the diffuser). With all this however, like very much what byndbad914 did with the louvered diffuser on his track car. Looks racey and subtle; if I would have known at the time, I would have simply gone that route instead.

I'll get to the piping in the next post.