LFX Engine Swap (GM V6) at GWR

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Ryan @ GWR
Posts: 497
Joined: Fri Oct 17, 2014 11:37 pm

Re: LFX Engine Swap (GM V6) at GWR

Post by Ryan @ GWR »

Ok it's about time I get things up to date!

Sorry for the lack of updates, work on the car has continued. Since covid hit we've been busier than ever at Goodwin Racing (a good problem to have) and that's meant that with the little spare time I have it often comes down to whether I want to use that time to build the car, or write about it... and I'm determined to finish this thing up and get back to the track, so it's been head down and getting after it for the past year.

There's a lot of updates to make, so to keep things digestible I'll break it up into smaller chunks and do those updates over a little time here.

First update: the fuel system at the motor.

For background, when I added the supercharger in 2019 we ran up against several issues with both physical fuel supply not being able to keep up and also with the ECU that wasn't happy to see certain values very far outside of expected ranges and it kept trying to step in and reign things in, though not in any sort of consistent manner, and HP Tuners didn't seem to be able to access deep enough into the tables in the factory ECU to effectively shut all of that off. To give an idea of how dramatic it was, I could do three dyno pulls and get almost a 100 hp spread across them. This made for a car that was nearly undriveable.

An aftermarket ECU was needed. But most can't control direct injection (only Motec and a couple other very high end options). It would be a huge commitment to go with one of those options, and if I kept the DI system I would still be inherently limited by the physical fuel flow abilities of that system, or the very small selection of aftermarket DI parts.
Instead, I decided to go the other direction and completely eliminate the direct injection, converting to a port injection system with more traditional injectors, no mechanical fuel pump, etc. That change would open up my ECU options massively, and I would also completely eliminate the physical fuel supply limitations as there's no end of aftermarket big flow solutions for a traditional system.

This route presented plenty of challenges as well, just different ones. The largest one is, obviously, there's no port injection system for the LFX.

One piece to the puzzle: a lower intake manifold from a very rare CNG (compressed natural gas) LFX. GM made very few of these, but there were some Impalas that had an auxillary CNG port-injected system in addition to the DI system. This lower manifold has the right footprint both top and
bottom, and provided me with ports for the fuel injectors.

First mock-up of that manifold on the LFX, and in the picture I'm already starting to figure out the next step; fuel rails:

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The CNG fuel rails and injectors won't work for a normal fuel system, so I needed to create a rail and injector set up to work with this new manifold.

With this new setup, I'll be running 6 x Injector Dynamics ID 1300x:

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Due to the port placement, the rail has to be a few inches away from the injector, and at a different angle. This means the rail needs "fingers" that extend to the injector. The fingers need to be precision sized at both ends, bent at an angle, rigid, and also need to seal to the rail. This lead me down a whole spiral of researching the mechanics of o-rings and seals so I could design this to seal properly, and then figuring out how to make the necessary multi-piece design.

Some progress shots:

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Pressure testing:

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Polished and anodized:

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And that's a finished set of one-off fuel rails test fit on the spare motor:

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This can now be fed by a normal fuel supply system at normal fuel pressure. FPR will be mounted on the back of the motor near the rail and then split to both rails. And this will now be a return system with return line exiting the rails and going back to the tank.
I just need to make a couple lines and the fuel injector wiring sub harness and then this will be installed on the main engine in the car.

To complete the elimination of the DI system, the mechanical pump was removed from the back of the head and covered with a plate, and the injector ports were drilled/tapped and plugged:

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More to come soon!
Ryan @ GWR
Posts: 497
Joined: Fri Oct 17, 2014 11:37 pm

Re: LFX Engine Swap (GM V6) at GWR

Post by Ryan @ GWR »

With the change to a universal ECU, it didn't make sense to retain the GM throttle pedal and TB and have to work out the calibration and quirks of those - far easier to convert to a well known TPS and DBW TB. So I now have a TPS on the Tilton throttle pedal and made an adapter to fit a Bosch throttle body from a Porsche 997 application to the LFX intake manifold:

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jboemler
Posts: 304
Joined: Fri Oct 10, 2008 6:15 pm
Location: Mukilteo WA

Re: LFX Engine Swap (GM V6) at GWR

Post by jboemler »

Wow, you just continue to amaze. :shock:
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