Starting my rally build

[j_green]

Finally committed to a direction for my '74 project that makes the most sense for what I think will be the most fun, and makes the most sense for the car as it sits- going to make it a full spec stage rally car. Initially I didn't want to do anything with it that required a full permanent roll cage, but after sitting with it for a while I'm convinced that a street legal rally car is the way to get the most fun out of this car.

If I build it to ARA spec I can also use it for hill climb events here in Colorado (and who knows maybe Pikes Peak someday) as well as snow/ice events and rallycross, so it should be pretty versatile and give me year-round fun.

I'd love to get some advice from any of you have built track cars (or especially rally/hill climb cars) on roll cages, which is the most critical thing at the moment. I'm going to get some quotes today from some local shops for having them just do the entire thing, but I've also found a couple pre-fab weld kits out there that could be promising but I'd love to get some actual first-hand feedback on them before I go that route. There's two that look like they could work, one from Autopower (sold by Evasive) and one from Safety Devices (sold by stable energies). Curious if anyone has used either of these kits and has feedback on the fit/quality as well as FIA 253 compliance? I'll get specs and answers from the vendors before ordering obviously, but haven't found much in the way of actual reviews on these. Also open to other options if they're out there, let me know!

My other option is to finally buy a bender and just build one myself, but the time commitment there doesn't really make sense for me.

I'll probably make this a bit of a build thread as I get going, but for now here's some of the current progress which should help ease any worries about me chopping up a clean car for this.

Car was a bit of a rust bucket when I got it, and had already been chopped for a hacky fiberglass widebody conversion. I've done all the structural rust repair and quite a bit of reinforcements/bracing. Still some cosmetic fixes and actual body work left to do, which is a part of the equation here.
Engine was solid though and had been rebuilt by a reputable shop here, and I did a full EFI conversion about 6 months ago. I got a rebuilt 915 and brand new clutch/flywheel (didn't opt for the LSD at the time, oops) and a rennline shifter which I don't love yet (hopefully it breaks in a bit with driving). Finished doing the elephant racing coilover conversion in the rear and still running the torsion bars in the front.

So it's at a point now where I can either dump a bunch of money into to making it a nice street car (paint/body/interior) or I can dump a bunch of money into it and make it a race car. By my math I should get about 1.5x more smiles/$ by doing a race car... we'll see how that pans out.

[Tom '74 911]

I am all for your project!

On the cage, I will offer an opinion... do NOT skimp on the cage. It is one of those base-level infrastructure items that can not be changed or updated in the future without great effort. Do it correctly the first time. If you don't have the time, skills or tools to build it yourself, pay someone to put one in for you. A good one will be expensive... but I guarantee that you will not care about the cost as you slide sideways at a high rate of speed toward a wall, tree, rock... (insert any hard object here). Do some research about what you want, what is legal and what is required for any group that you plan to run with - they are generally all pretty similar. A good cage builder should be familiar with the rules and requirements of lots of rulebooks and be unfazed by any extra bars required by rally organizations... try to find someone familiar with early Porsches...

While I 100% cheer on any and all home builders and penny pinchers, it pains me greatly to see a crappy cage. Once it's in, if it's not 100% awesome, it's really costly and hard to fix and is a stain on the finished car.

You can take that for what it's worth, which is not much... just an opinion.

Tom

[Tom '74 911]

Sorry, one more thing... if you're changing to coil-overs, you are going to want to run the cage through the front & rear firewalls to the front AND rear shock towers... lots of example photos around if you do some searching...

[j_green]

Thanks for your input Tom! I think you're spot on with that take on the cage, I really like doing things myself but the cage being so fundamental to the build and potentially critical in keeping me from being dead... I'm going to get a professional to do it. Talking to a couple of shops now to make my pick, but I'm fortunate to live near a few really good shops that regularly do Pikes Peak Hill Climb cars (among other cool race series) so finding a good shop that knows what they're doing for hopefully a reasonable price doesn't seem like it'll be too hard.

As for coilover bracing, that's a good point I'll just have to make sure it's legal for the series I want to enter in. I remember when doing the cage for my E36 one of the rule books specifically restricted that.

Fortunately I did myself a favor when installing the rears while I had everything stripped and welded in the bracing kit from Elephant. So even if I'm not able to run the cage to towers it'll hopefully hold up for the most part... time will tell!

[Bill Verburg]

w/ or w/o a cage the rears need reinforcement when coil overs are used.

[j_green]

This is the bracing I did while the engine was out, also did the reinforcement for the spring plate mounts on the chassis. We’ll see how all this holds up to rally driving..

[nospiners]

Tell us about the EFI conversion, it looks awesome !

[j_green]

Thanks! I’m pretty happy with how the whole thing turned out, I could probably do a whole thread just on the EFI conversion but here’s the distilled version.

I thought it’d be fun to try doing it from scratch, so I ended up piecing the whole intake/injection/ignition system together. I designed and 3D printed quite a few of the main elements for the intake, and got some used 964 manifolds. Converted to drive by wire using a standard Bosch unit, with another module I designed and 3D printed/machined to adapt the pedal sensor to work with my existing pedals so I could keep my nice adjustable rennline set.

The intake runner/adapters are 3D printed aluminum and the plenum and crossover are a nylon/carbon fiber. Very interested to see if the nylon parts hold up to the abuse.

Running everything with a haltech elite and a haltech pdm, VAG coil-on-plug coils, and deatschwerks injectors. There’s enough fuel capacity to do a turbo at some point, but that’s a later project.

Haven’t gotten it properly tuned yet, but it does run and drive.

[j_green]

Some good progress over the long weekend. Tires are here, still figuring out a couple things with wheel selection but hopefully I’ll get some answers and a quote back soon. Seat is mocked up, it’s pretty big for this car but looks like it’ll work, just have to get rid of the factory mounts to get it lower and further back.

Dropping it off next week for the cage, after that things should get moving pretty quickly!

[j_green]

Got a pretty exciting delivery today, can’t wait to get the car back now and get these mounted up!

[decisive1]

I just stumbled across this and am now following this very cool build. Those Braids will look nice on the car.

I really like the fact that you have developed your own intake and intake adapters, and then had them printed in aluminum. Beautiful work! Based on my limited experience I know that it was no small feat to achieve. I am curious what the approximate cost was to have a set of the intake runners and intake adapters printed in aluminum though.

Also, is that finish on the runners Cerakote?

[sub-zeror]

very cool !!

[Jonny042]

Originally Posted by sub-zeror

very cool !!

Agreed!

Subscribed.

[j_green]

Originally Posted by decisive1

I just stumbled across this and am now following this very cool build. Those Braids will look nice on the car.

I really like the fact that you have developed your own intake and intake adapters, and then had them printed in aluminum. Beautiful work! Based on my limited experience I know that it was no small feat to achieve. I am curious what the approximate cost was to have a set of the intake runners and intake adapters printed in aluminum though.

Also, is that finish on the runners Cerakote?

Thanks! Yeah it was definitely a big design project, tons of iterations before I got something that I was happy with (and honestly there are still changes I'd make). But it was very fun and I learned a ton in the process.

So the individual adapters were 3d printed aluminum, which I got in early 2024, and cost around $400 for all six.. no idea what they would be now with tariffs and everything. The runners/manifolds were just used 964 units, not too expensive at the time. The plenum and resonator delete tube (whatever you'd call it) were printed in PAHT-CF on my printer.. so probably about $40 in filament. All in I'd guess about $6-700 for all the intake "hard" parts.

Everything is powder coated, except the printed aluminum adapters- those are just raw/bead-blasted

[j_green]

Originally Posted by Jonny042

Agreed!

Subscribed.

Thanks guys!

Jonny I've been watching your latest carbon build unfold for a while, you set quite a standard... I'll try not to disappoint!

[Queefchief]

This is gonna be awesome!

[j_green]

Pretty big update, the car is fully caged and back home. Threw the wheels on and started mocking up some of the body work. Pretty excited to have it at this point, ordered some material to get the seats mounted and a pedal box so there's some fun stuff on deck

[decisive1]

Originally Posted by j_green

Thanks! Yeah it was definitely a big design project, tons of iterations before I got something that I was happy with (and honestly there are still changes I'd make). But it was very fun and I learned a ton in the process.

So the individual adapters were 3d printed aluminum, which I got in early 2024, and cost around $400 for all six.. no idea what they would be now with tariffs and everything. The runners/manifolds were just used 964 units, not too expensive at the time. The plenum and resonator delete tube (whatever you'd call it) were printed in PAHT-CF on my printer.. so probably about $40 in filament. All in I'd guess about $6-700 for all the intake "hard" parts.

Everything is powder coated, except the printed aluminum adapters- those are just raw/bead-blasted

Thanks for the info. That PAHT-CF is a pretty awesome filament for under hood applications. Super durable and heat resistance up to 250C if I recall. Nice surface finish and the price isn't too bad also.

What is your plan for finishing the fenders?

[3literpwr]

What cage spec did you end up building? If you built it to ARA spec, you should get the car log booked and you'll be able to run more events.

[j_green]

Originally Posted by decisive1

Thanks for the info. That PAHT-CF is a pretty awesome filament for under hood applications. Super durable and heat resistance up to 250C if I recall. Nice surface finish and the price isn't too bad also.

What is your plan for finishing the fenders?

Yeah it's a cool material. between that and the printed aluminum it'll be pretty interesting to see how everything holds up to the temps and the vibrations/shocks, but I'm pretty optimistic about i all.

The fenders are the roughest part at the moment, this thing was pretty chopped up and rusty from a previous widebody conversion. Not going to do much rust repair, but planning on eventually getting carbon/kevlar fronts (full fender not flares) and rear flares.

For this coming year though I think I'm just going to fit up the old fiberglass flares I pulled off it a couple years ago and just make it presentable. Mostly because I want to do SC flares in the rear but keep it turbo-width up front and I want to make sure I actually like that before committing to spending money on anything