V8 Roadsters LS3 RX8 Build
09-01-2014, 07:09 PM
#1
V8 Roadsters LS3 RX8 Build
Howdy all!
I've actually been working on my build for the past few months but I finally decided to start documenting it.
After deciding I needed a new project I picked up an '04 Brilliant Black GT with just over 100k miles last October. It was a one owner car that was very well taken care of, the interior was mint and the exterior had only a few easily fixed cosmetic issues. I ended up picking it up for $4,000 which I thought was a steal for a clean running car. It still had the original engine but I could tell that it was low on compression(it ended up testing at the lower limit of Mazda's Spec.)
I had been looking into the options on swap kits and wasn't too happy with what I saw available. The Hinson kit works, but I didn't like that it relocated the stock rack, and that you had to keep the factory ECU. The LS1RX8.com kit looks to be a copy of the Hinson kit although it looks like they have better customer service but to me it had the same downsides with the rack and ECU.
I knew V8 Roadsters had been working on a kit but it wasn't set for release yet. I contacted Steve and Shandelle over at V8R and started discussing the what their kit offered and I like what I heard. Over the course of a few months I ended up convincing them to let me test their Beta kit for them.
So here is the build sheet:
GMPP crate LS3
F-Body Oil Pan
Improved Racing Baffle
CTS-V Accessories
GTO T56
Ford 8.8 IRS 3.27 gears
Wavetrac 31 Spline T2R Torsen
V8R Hydraulic Steering Rack Conversion
V8R Tubular Front Subframe
V8R Transmission Mount
V8R Ford 8.8 Mounting kit
Things left to figure out:
Connecting the GM harness to the RX8
Remove unnecessary circuits from the factory engine harness(in Progress)
Cooling system
Exhaust (which long tubes fit, X-Pipe?)
Intake Plumbing
Air Conditioning
Re-Plumbing Brake lines to eliminate the DSC/ABS Module
GM Throttle Pedal Mount
Design a Bracket to mount the stock shifter in the stock location
I'll update with more pictures and detail as I progress.
Anyways on to the pictures!
I've actually been working on my build for the past few months but I finally decided to start documenting it.
After deciding I needed a new project I picked up an '04 Brilliant Black GT with just over 100k miles last October. It was a one owner car that was very well taken care of, the interior was mint and the exterior had only a few easily fixed cosmetic issues. I ended up picking it up for $4,000 which I thought was a steal for a clean running car. It still had the original engine but I could tell that it was low on compression(it ended up testing at the lower limit of Mazda's Spec.)
I had been looking into the options on swap kits and wasn't too happy with what I saw available. The Hinson kit works, but I didn't like that it relocated the stock rack, and that you had to keep the factory ECU. The LS1RX8.com kit looks to be a copy of the Hinson kit although it looks like they have better customer service but to me it had the same downsides with the rack and ECU.
I knew V8 Roadsters had been working on a kit but it wasn't set for release yet. I contacted Steve and Shandelle over at V8R and started discussing the what their kit offered and I like what I heard. Over the course of a few months I ended up convincing them to let me test their Beta kit for them.
So here is the build sheet:
GMPP crate LS3
F-Body Oil Pan
Improved Racing Baffle
CTS-V Accessories
GTO T56
Ford 8.8 IRS 3.27 gears
Wavetrac 31 Spline T2R Torsen
V8R Hydraulic Steering Rack Conversion
V8R Tubular Front Subframe
V8R Transmission Mount
V8R Ford 8.8 Mounting kit
Things left to figure out:
Connecting the GM harness to the RX8
Remove unnecessary circuits from the factory engine harness(in Progress)
Cooling system
Exhaust (which long tubes fit, X-Pipe?)
Intake Plumbing
Air Conditioning
Re-Plumbing Brake lines to eliminate the DSC/ABS Module
GM Throttle Pedal Mount
Design a Bracket to mount the stock shifter in the stock location
I'll update with more pictures and detail as I progress.
Anyways on to the pictures!
Last edited by Stubbs; 09-02-2014 at 07:44 PM.
09-01-2014, 09:06 PM
#3
rev it up
I like how the engine sits way back into the engine bay. I have seen conversions where the engine sits all the way to the front.
Looks like a lot of work ahead in figuring out the electronics. Good luck and look forward to the progress reports.
Looks like a lot of work ahead in figuring out the electronics. Good luck and look forward to the progress reports.
09-01-2014, 10:09 PM
#6
The engine seems to sit a little farther back and lower than some of the other kits but I've never measured them so I'm not certain. The shifter sits just aft of the center of the factory shifter hole.
The wiring looks more difficult than it is. I'm removing the parts of the harness that I don't need any more such as the remnants of the engine harness, the EPS wiring, the cooling fan wiring etc...
You don't need to remove them I'm just doing it to clean up the engine bay. I'm using a PSI Conversions harness which makes the GM and RX8 harness integration only a handful of connections.
I'll keep posting pictures as I make more progress.
The wiring looks more difficult than it is. I'm removing the parts of the harness that I don't need any more such as the remnants of the engine harness, the EPS wiring, the cooling fan wiring etc...
You don't need to remove them I'm just doing it to clean up the engine bay. I'm using a PSI Conversions harness which makes the GM and RX8 harness integration only a handful of connections.
I'll keep posting pictures as I make more progress.
09-02-2014, 10:25 AM
#9
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The engine seems to sit a little farther back and lower than some of the other kits but I've never measured them so I'm not certain. The shifter sits just aft of the center of the factory shifter hole.
The wiring looks more difficult than it is. I'm removing the parts of the harness that I don't need any more such as the remnants of the engine harness, the EPS wiring, the cooling fan wiring etc...
You don't need to remove them I'm just doing it to clean up the engine bay. I'm using a PSI Conversions harness which makes the GM and RX8 harness integration only a handful of connections.
I'll keep posting pictures as I make more progress.
The wiring looks more difficult than it is. I'm removing the parts of the harness that I don't need any more such as the remnants of the engine harness, the EPS wiring, the cooling fan wiring etc...
You don't need to remove them I'm just doing it to clean up the engine bay. I'm using a PSI Conversions harness which makes the GM and RX8 harness integration only a handful of connections.
I'll keep posting pictures as I make more progress.
09-02-2014, 01:57 PM
#14
I'm using a hydraulic power rack. My Miata and Mr2 both had manual racks. When I was younger that didn't bother me, but power steering is a must now. Ditching the EPS is necessary to keep the stock steering geometry.
In stock form the ls3 will make 430hp and 400lb/ft of torque to the ground with long tubes and a tune. After break-in and de-bugging I'll be doing heads and a cam with the goal of breaking 500whp. The stock diff might hold that for a while, but I'd rather have a 8.8 and be bullet proof from the start. Also the stock diff is 4.30 I'm using 3.27s in the 8.8 to better match the GTO T56 gearing.
In stock form the ls3 will make 430hp and 400lb/ft of torque to the ground with long tubes and a tune. After break-in and de-bugging I'll be doing heads and a cam with the goal of breaking 500whp. The stock diff might hold that for a while, but I'd rather have a 8.8 and be bullet proof from the start. Also the stock diff is 4.30 I'm using 3.27s in the 8.8 to better match the GTO T56 gearing.
09-02-2014, 07:38 PM
#16
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I'm using a hydraulic power rack. My Miata and Mr2 both had manual racks. When I was younger that didn't bother me, but power steering is a must now. Ditching the EPS is necessary to keep the stock steering geometry.
In stock form the ls3 will make 430hp and 400lb/ft of torque to the ground with long tubes and a tune. After break-in and de-bugging I'll be doing heads and a cam with the goal of breaking 500whp. The stock diff might hold that for a while, but I'd rather have a 8.8 and be bullet proof from the start. Also the stock diff is 4.30 I'm using 3.27s in the 8.8 to better match the GTO T56 gearing.
In stock form the ls3 will make 430hp and 400lb/ft of torque to the ground with long tubes and a tune. After break-in and de-bugging I'll be doing heads and a cam with the goal of breaking 500whp. The stock diff might hold that for a while, but I'd rather have a 8.8 and be bullet proof from the start. Also the stock diff is 4.30 I'm using 3.27s in the 8.8 to better match the GTO T56 gearing.
My EPS went out for a sec this weekend, seemed awful!
*ps, I know that's not the same as having a manual rack.
09-02-2014, 07:44 PM
#18
This is confusing, but maybe I'm dense. The OP notes a manual rack, but this post notes a hydraulic rack. Where is this rack sourced from, either way? It keeps the stock geometry?
My EPS went out for a sec this weekend, seemed awful!
*ps, I know that's not the same as having a manual rack.
My EPS went out for a sec this weekend, seemed awful!
*ps, I know that's not the same as having a manual rack.
I can't go into specifics on the rack just yet, but it's a modified OEM Mazda rack. It retains the factory RX8 geometry.
Last edited by Stubbs; 09-02-2014 at 10:16 PM.
09-03-2014, 09:28 PM
#22
Are you required to keep the factory subframe in your class?
As for the brakes, I'm replacing the ABS/DSC with a proportioning valve from a non-abs Miata. I've never built hardlines before so that'll be a bit of a learning curve.
09-03-2014, 10:41 PM
#23
The rack is probably not compatible with the stock sub-frame since the steering shaft sits at a different angle than the RX8 rack.
Are you required to keep the factory subframe in your class?
As for the brakes, I'm replacing the ABS/DSC with a proportioning valve from a non-abs Miata. I've never built hardlines before so that'll be a bit of a learning curve.
Are you required to keep the factory subframe in your class?
As for the brakes, I'm replacing the ABS/DSC with a proportioning valve from a non-abs Miata. I've never built hardlines before so that'll be a bit of a learning curve.
Would be interesting to know the exact differences between the two racks to figure out if it would work.
I'm not required to keep the stock sub frame, just the stock suspension pickup points. But the reason I don't want one is because my REW engine mount is already designed to work with the stock subframe and also I don't feel like dropping money for a tubular one.
09-13-2014, 07:26 PM
#24
I've got most of the harness stripped down. I eliminated most of the ECU wiring, all of the Electronic steering, and all of the Fan harness, and the relays for the fan and fuel pump. I Removed the fan and fuel pump relays since I'm going to use a a stand alone set with the GM harness. I'll be using a Lincoln Mark VIII fan which has a big current draw so the stock wiring and relays wouldn't be adequate.
Here's the pile of stuff I've pulled off.
Here's what I'm retaining from the RX8 harness:
The AC Amplifier wire sends a 0-5V signal for the engine coolant temp to the AC Amp. I'm hoping I can just splice the GM sensor since it outputs a similar signal. It's probably not going to be that easy though.
The Reverse switch wiring is two wires that run through the harness to the ECU harness then through the Engine harness to the transmission. I've pulled them back to the driver fender loom and I'll be splicing on a GM reverse switch pigtail.
There are 6 wires that go to the Accelerator pedal position sensor. I'll be cutting them off on both sides of the bulkhead pass through. I would have preferred to remove the entire length of the wires but Mazda potted the bulkhead pass through with urethane which makes it very difficult to remove.
The two Canbus wires will likely be cutoff as they will likely be tapped in the cabin instead of the engine bay.
The two Evap Pump wire will be shortened, rolled up, and retained just in case I need that part of emissions to work.
The 12V ECU constant will be cut off since there isn't a need for it.
This one makes me a little nervous. It's a ground from the ECU but I haven't been able to identify exactly where it goes to on the wiring diagram. It'll be rolled up and set aside for now.
Fuel pump power wire. It'll be connected to a new relay triggered by the GM ECU.
Starter and AC clutch relay trigger wires come to the fuse box from the ECU
Brake Switch will be connected to the GM ECU
This is the Cruise control power, signal and clutch switch. They aren't being used right now as the GM computer uses a different method of cruise control signaling. They'll be rolled up and set aside for now.
That's the high level look at what I'm doing on the RX8 wiring. I'll update as I get the GM Stuff finalized.
I also did some work on getting the stock shifter back on. It's about as simple as it gets, a piece of angle with a bolt welded on. It's fairly close to the stock position, but I think it's a little bit taller
Here's the pile of stuff I've pulled off.
Here's what I'm retaining from the RX8 harness:
The AC Amplifier wire sends a 0-5V signal for the engine coolant temp to the AC Amp. I'm hoping I can just splice the GM sensor since it outputs a similar signal. It's probably not going to be that easy though.
The Reverse switch wiring is two wires that run through the harness to the ECU harness then through the Engine harness to the transmission. I've pulled them back to the driver fender loom and I'll be splicing on a GM reverse switch pigtail.
There are 6 wires that go to the Accelerator pedal position sensor. I'll be cutting them off on both sides of the bulkhead pass through. I would have preferred to remove the entire length of the wires but Mazda potted the bulkhead pass through with urethane which makes it very difficult to remove.
The two Canbus wires will likely be cutoff as they will likely be tapped in the cabin instead of the engine bay.
The two Evap Pump wire will be shortened, rolled up, and retained just in case I need that part of emissions to work.
The 12V ECU constant will be cut off since there isn't a need for it.
This one makes me a little nervous. It's a ground from the ECU but I haven't been able to identify exactly where it goes to on the wiring diagram. It'll be rolled up and set aside for now.
Fuel pump power wire. It'll be connected to a new relay triggered by the GM ECU.
Starter and AC clutch relay trigger wires come to the fuse box from the ECU
Brake Switch will be connected to the GM ECU
This is the Cruise control power, signal and clutch switch. They aren't being used right now as the GM computer uses a different method of cruise control signaling. They'll be rolled up and set aside for now.
That's the high level look at what I'm doing on the RX8 wiring. I'll update as I get the GM Stuff finalized.
I also did some work on getting the stock shifter back on. It's about as simple as it gets, a piece of angle with a bolt welded on. It's fairly close to the stock position, but I think it's a little bit taller
