Budget Review - End of Planning Phase

Yesterday, I placed the order for the GTM. It should show up some time in mid June. This essentially ends the planning phase of the build. The kit purchase is the single largest line item of the entire build. So I think it is a good time to review the budget. My initial estimate was $68,200. When I refined this number, I came up with  $72,200. I set the budget at $70,000. My projected cost is currently 20% higher than that. So where did I go wrong, and importantly, why did I go wrong.

I think it is still possible to build the GTM for something between $55,000 and $60,000. This means you are making no upgrades, and use everything from a donor, including the engine and a recondition Porsche G50 transmission. There is nothing wrong this approach, but I wanted something better. If I'm going to pour three years into this project, then I want a car at the end of this project that is unique and tailored to my specifications.

The following chart shows expenditures to date, based on my original estimate ($70,000), adjustments to specific line items, actual costs and variance to the adjusted line estimates. I have actually done very well to date. I am well within my estimates. I think these categories are easier to price.

Item	Estimate	Adjusted estimate	Actual	Variance
brakes	2000	2000	1945	55
donor	11000	11000	4649.02	6350.98
wheels	3200	3200	1380.99	1819.01
Kit	25000	22967	22692	275
Totals	41200	39167	30667.01	8499.99
Pct of original Estimate	58.86	55.95	43.81
Pct of Revised Estimate	50.24	47.76	37.4

I saved money by going with a donor parts kit, and I haven't purchased the Nitto Invo tires.

Technology and add ons have increased the cost. Yes, mission creep has struck!

These are the categories where I blew the budget estimate:

Item	Estimate	Adjusted estimate
ISIS	0	3108
harness	1500	0
Paint	3000	9000
options & add ons	4000	7714

When I started this project, I didn't even know that ISIS power existed. Sometime last fall I came to realize ISIS was the only sensible power system for the GTM. It provides a programmable and scalable power management system.

The engine harness fits nicely with the engine budget. I think I'm within 10% of both the original transmission and engine estimates. The current engine  slated to drop into the GTM is a LS376/525 with electronic fuel injection. I think it will be relatively simple to get this to just under 600 HP with the optional cold air intake (part of the kit order) and the Kooks custom exhaust (part of the options).

I had no idea how much the paint job would cost and I plugged a number in. I was way off. 

The real mission creep is in the options and add ons section. 

• There are a bunch of body work pieces that I will order from Vraptor Speed Works.
• The paddle shift system to replace the conventional shifter in the center console. This is to make room for additional electronics and ISIS hardware.
• The Ram Lift system to protect the GTM body from unsightly scrapes and damage.
• One thing not reflected at the moment is the APR Racing Wing and mounting hardware. This is an enhancement that is not required to complete the car and can be added at a later date. So I have not reflected this in any of the budget figures.

My conclusions for the over budget issue. The GTM is a work in progress and the build is stretched over 3 years. Technology and ways to do things better will present themselves through out the build. If this were a 3 month project and I had all the money up front, then line items would be cast in stone. Due to the length of the build and the nature of the car, it is foolish to ignore technological innovations that will enhance the finished product. Obviously, I should have included a bigger number for the options and add ons.

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.

Donor Parts Kit (Purchased)

Over the weekend the GTM Donor Parts kit offered by FPARTS, went on sale at 10% off on Ebay. I've been watching this auction since May. It has been relisted a couple of times, and according to FPARTS, there were 3 kits available.

The economics for the donor parts work out like this:

• A new parts kit from SMC Performance is starting to push $12,000. 
• The GM Performance Parts kit never really materialized. This was something announced over a year ago.
• A salvage title C5 is running around $10,000
• The FPARTS kit dropped down to $4409 for 2 days over the weekend.

The items not included are the following:

• Brake lines
• Radiator
• Alternator
• Brake pads (Duh)
• A/C compressor and clutch

I am still planning to get the Big Brake Kit upgrade for Z06 Corvettes. This covers rotors, calipers, pads, fluids and brake lines. I have verified that the Factory Five 18 inch wheel upgrade accommodates this brake kit.

I plan to go with a bigger radiator (probably a DeWitts) anyway.

The alternator and A/C compressor need to matched to the engine accessory kit. Again, I am going with a bigger engine than you could find in a salvage C5 (i.e. LS376).

FPARTS does ask for a little patience. They need to put the donor kit together, and that includes pulling parts off a couple C5s in their salvage yard. I hope to see everything in the next 10 days.

It feels good to take a step forward on this project.

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.