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]

Thought I'd take y'all through the AC system. I posted some of these photos before in answer to another thread, but hopefully these will provide more info.

I bought a Hot Rod Air under dash evaporator based on it's compatability with my existing LS1 variable volume compressor. Vintage air claims their system is not compatible with this copressor, therefore my decision. The Hot Rod Air evaporator includes heat, and has defrost. The Hot Rod Air guys were very helpful, however they apparently went out of business not long after I received the unt from them (IMG:style_emoticons/default/sad.gif) For the condensor, I bought a Vintage Air 12"x20". Since the LS1 PCM has the capability to control the AC, I decided to run a GM AC refrigerant pressure sensor rather than a trinary switch. The GM PCM controls the compressor cycling from the AC request signal output, turns on the radiator fans (and truns them off over 40 MPH), and of course monitors the pressure.

It turned out that the biggest challenge, was routing the refrigerant hoses. The 914 just doesn't give you many favorable options in this regard, so I did some serious head scratching and came up with the following. I really dislike the original 914 dealer installed hose routing where they punch holes through inner fender panels ans such, so I went in another direction. The first decision was to use reduced diameter barrier hose, which as the name implys, its diameter is smaller that the standard hose of the same size. Though the fittings are less common, the smaller diameter hose made the routing much nicer. Starting at the compressor, I routed the -8 pressure and -10 suction hoses through the engine firewall and into the lower right passenger side using bulkhead fittings. The hoses run under the engine shelf, pass through the firewall, then with 90 degree ported fittings, the hoses sweep downward and run along the floor where it meets the long in the cabin. You'll see in the photos how the ported fittings intrude into the cabin behind the seat. To keep the seat from crashing into the fittings, I made some seat stops in the seat rails. I only needed to shorten the seat travel by 7/8", so it is really un-noticable. I painted the fittings flat black, so they go un-noticed (and they're behind the seat anyway). Held in place with Adel clamps, the hoses run forward; the -10 to the evaporator, and the -8 forward through the lower floorboard bulkhead, under the fuel tank, through the front trunk blukhead, and on to the condensor. The -6 high pressure hose runs from the condensor to the drier. The GM refrigerant pressure sensor is attached to one of the un-used drier ports using an adapter. From the drier, the -6 hose parallels the -10 hose under the fuel tank and through the floorboard and to the evaporator. By running the hoses along the floor and long joint, once the carpet is in place, it is completely un-noticable.

Back at the compressor, I had to get a custom compressor block made such that the hoses would point in the most favorable direction; that was a tough one, as there's so little room to route the hoses effectively away from the headers and keep from abrading against the chassis. I also made a heat shield between the header and the compressor.The custom compressor block was made by Doc's Blocks (Stark Mfg), which would make anything custom from your drawing but unfortunately they've changed thier business model and no longer do custom work and sell only through distributors.....This is really too bad, as they were a fantastic resource up until that time....and their prices were great!

For the heat function, I ran two -8 hoses through the passenger side heater duct. I first wrapped them with extra thick electricians tape to help guard against any incidental abrasion. I added 1/2" (-8) x 5/8" adapters on heater core side which made things less tidy than I would have liked, but they're hidden out of sight anyway. The heater (hot water) control valve (HCV) is in the engine compartment. The LS1 heater water flow system logic is such that the HCV is normally open with the engine off (no vauum), but once the motor is started, the vacuum closes the HCV. This requires a different approach to the vacuum switching valve (VSV). You need a VSV that is normally open until heat is requested at which point the VCV closes and vents the NO side which allows the HCV to open. I found a VSV from a Toyota (NAPA P/N: CRB 226873) that had the appropriate logic, so all is good. For a vacuume source, I ran some 1/8" nylon vacuum tubing from the motor to the VSV through the center tunnel, then from the VSV back to the HCV. The nylon tubing is small and easy to route.
As always, please ask.