58x Crankshaft Signal Converter

When I purchased the donor kit from FPARTS (see posts Donor Parts Kit (purchased), Donor Parts Kit Arrives, Donor Parts Kits (Catalogued)), I received an engine harness and PCM for the LS1 engine. However, I plan to purchase a LS376/480 crate engine and this presents a problem.

The LS1 engine harness and PCM are not compatible with the LS3 engine. The reason for this is the LS1  is a Gen III engine and the LS3 is a Gen IV engine. This change took place when in 2006. The major problem is the Gen III engines us a 24x reluctor wheel and the Gen IV engines use a 58x reluctor wheel. This is the crank signal protocol. Basically, a 58x signal does not work on a 24x harness and vice versa.

The oddity is the 2005 Corvette (the first year of the sixth generation Corvette) in that it has a LS2 Gen IV engine with a 24x reluctor wheel.

My initial thoughts were that once I got everything running on the GTM with the LS3 engine, I would run to Ebay and put the LS1 harness up for auction. Conservatively, the engine harness and PCM represent about 20% of the donor kit cost, plus the cost of a new harness and PCM compatible with the LS3 is around $1800 - $2000. That's a swing of $3000 - OUCH!

There's a better way. I read in  GM LS-Series Engines: The Complete Swap Manual that Lingenfelter Performance Engineering makes 58X - 24X Crank Sensor Trigger Conversion Module.

For $250, I can purchase a plug & play module, salvage my investment and save $2000.

Kindle Power

A Kindle is a tremendous tool. It is far more than a simple E-Reader. A Kindle account is free to set up, and the reader app can be downloaded to a myriad of different platforms, including the iPad, Android, and PC platforms.

A book on my Kindle is accessible everywhere I have a suitable platform. I have never done an engine swap/mount before, but there are plenty of resources out there to bring me up to speed. The GM LS-Series Engines: The Complete Swap Manual is a tremendous DIY guide to mount an LS Series engine swaps and mounts. Best of all it has a Kindle edition ($3 cheaper than the hard copy).

I order the book. A minute later it arrives on my Kindle. Five more minutes, I have my head stuck inside the engine compartment of my Corvette.

Ah, but you say the Kindle is black & white, it is a bit bulky (when there might not be space under the car). I agree, but my Apple iTouch is just the right size and it is in color and I can zoom things in and out as needed.

So I have a couple of days left before I tuck my Corvette away until after New Years. Enough time (I hope) to get my head around the accessories rail, engine mounts and the transmission/clutch linkage.

Granted, the LS376/480 is a bigger engine, and the Mendeola transaxle is a different configuration, but the basics are the same. Before I can appreciate the specifics, I need to understand the basics.

Old vs. New: Engine

For me this is a no brainer. You certainly can save significant money going with a donor engine (e.g. LS1, LS6). The GTM achieved the its extreme performance numbers with a LS7 hooked to a Porsche G50 transmission, and 0 - 60 in 3.0 seconds flat is something everyone should sit up and take notice. If we take the nominal GTM curb weight of 2400, then the power-to-weight ratio for the demo car 0.210416 HP/lbs.

The curb weight for Corvette Z06 is 3180 pounds. The LS7 is the base engine for the Z06 and this has a p-t-w ratio of 0.158805 HP/lbs.

My 2003 C5 (as currently configured) has a curb weight 3214 pounds. It has a modified LS1 engine and it has a p-t-w ration of 0.124455 HP/lbs.

The base LS3 engine produces 430 HP. In a GTM, the p-t-w ratio is 0.17916 HP/lbs. This is already higher than the Z06, which has a published top end speed of 198 mph.

For emission conscious locales. GM provides green E-Rod engine with the same p-t-w ratio. I only include this engine for completeness. It is not on the list for engines in my GTM.

For close to the same money as the base LS3, there is a more powerful version called the LS376 engine that produces 480 HP. In a GTM, the p-t-w ratio is 0.2 HP/lbs. This engine set up approaches the powerful LS7 used for the demo car. Now we're talking! The MSRP is $8,075. If you shop around, this engine can be found for as little as $6,100.

Granted horsepower isn't everything, but it is the heart of the beast.

The Donor Car - Part 2

The donor car is a cost effective method for acquiring the parts needed for the build. The donor is a cadaver that will never roar down a twisting country road again. So you have to ask yourself what happened. The car either was the victim of a flood, theft or crash. (Stay away from the fire damaged ones. The reasons become obvious, once you look.) The insurance company deemed it unrepairable, and that means there was in excess of $20,000 damage to the vehicle. This number is based on the current replacement cost for a low end Corvette C5.

The major subsystems provided by the donor are as follows:

• Front suspension
• Engine
• Rear suspension
• Rear CV joints
• Emergency Brake Assembly
• Fuel Delivery
• Cooling system
• A/C 
• Brakes
• Miscellaneous (basically everything else)

Factory Five says the donor needs to be a C5. This is the path of least resistance, but many of these subsystems are common across generations for years 2003 to 2009. There is a substantial financial argument to be made for donor with a working engine.

My perfect donor is as follows:

• 2008/2009
• Larger wheels (18 front / 19 rear) - I'd scavenge these for the Big Yellow Toy.
• Big brake upgrade
• LS3/LS7 engine
• Intact suspension
• Intact instrumentation

This poor thing has too much damage for the GTM project. My first clue was lack of wheels and anything to hold them along the driver's side. The love of my life has already indicated that I need to make sure the wheels stay on the car.

This car on the other hand got hit on the passenger side. There is a substantial mess inside, but the mechanicals look good.

As I said, there is a substantial cost savings going the donor car route. The opportunity to acquire a working LS3 or LS7 engine plus the majority of the parts needed for assembly needs to be considered. Copart and Ebay are the easiest places to look for salvage or unrepairable titled cars.