Citroën Xantia Activa - Track cars should not roll!

Hi! Long time lurker, but almost first time poster.

I'm Fredrik, and I live in Linkoping, Sweden. After a couple (OK, maybe like five) years of doing Formula SAE, I needed to get my engineering and design cravings to work on something else (maybe something I could fit in?), so I figured I'd get myself a track car project. BMW? Porsche? Nah, sounds too simple. Why not something more ridiculously complicated that almost no one else have tried, so I need to make everything from scratch? Sounds good ... And also, this video.

Long story short; I'm trying to build a Citroën Xantia Activa as a track car. I think it will be fun! The Activa package was an option to the Citroën Xantia, which had "active" anti roll bars. The ARB is suspended by a hydraulic actuator at one end, which depending on steering wheel angle, steering wheel angle velocity and speed stiffens up or loosens up the ARB. But if a regular Citroën is complicated, this is even worse: I have a total of eleven gas spheres, and two extra hydraulic actuators on the car. A bit more information can be found here.

Some pictures!

It started somewhere along here:

To get here (actually getting a garage) took half a year:

Then me and the friend I share the garage with went berzerk and did this in one day:

Hood weighs in at a healthy 18,5kgs ...

This (uppper radiator mount, hood lock mount etc) weighs in at about 5kg, but the front bumper (sans foglights) is 8,3kgs! This car needs to get on a diet ...

Right now, focus is on examining the car and figuring out a) the general condition, b) what needs to be replaced, c) what can be removed and d) what can be moved backwards in the car. A diesel Xantia (the only one I have found figures for) has 62,6% of its weight on the front axle! The body seems in fairly good shape, but there are some hydraulic leaks that I need to fix and I need to do a general overhaul before the car gets assembled again. And of course, there is some rust. Couldn't miss out on that completely ... Hopefully, I can get it to a track in the spring.

just spent a quick minute skimming about hydropneumatic suspensions on wiki. you sir, are OUR kind of masochist! very nice!

https://en.wikipedia.org/wiki/Hydropneumatic_suspension

:ooking forwad to see where this build goes! I checked out bluej's wiki article. It seems like Citroen is the GRM go-to car when your Saab C900 is just too conventional or mainstream anymore

bluej wrote: just spent a quick minute skimming about hydropneumatic suspensions on wiki. you sir, are OUR kind of masochist! very nice! https://en.wikipedia.org/wiki/Hydropneumatic_suspension

Thanks! Yes, I am a little bit crazy. But my first dab at race cars was building FSAE cars, with none of us having any knowledge at all. I think I can see a pattern of getting in over my head here.

Not much has happened with the build. I have been removing floor mats, the seats and bought a spare engine. Hopefully, it's solid enough to serve as a base for a more built engine for the next phase of the project.

I'm looking for a race seat, FIA approved and fitting for me (195cm, 120kg approximately). Any suggestions? Also: tyres. I want semi race tyres (are they called R tyres in English as well?) with really stiff sidewalls and with a predictable behaviour. From 15" (in that case they really need to have a stiff sidewall) to 17" (since I will have quite low profile tyres if I run those, I guess sidewall stiffness will solve itself more or less?) and not extremely expensive. Any suggestions there?

And I think I need at least one picture:

Awesome car, but I can't help but think that these things must handle really strangely when it gets freezing outside.

ssswitch wrote: Awesome car, but I can't help but think that these things must handle really strangely when it gets freezing outside.

Reasonable temperatures are no issues at all; the pouring temperature of the oil is -51 degrees Fahrenheit, the oil is circulated and I guess heated to workable temperatures when passing close to the engine and the nitrogen is not affected at all. I can't really say what's happening if it is colder than that, but Citroën hydropnuematic cars have been quite popular in the north of Sweden where it certainly can get below -51, so I guess that it can be solved.

-51?

Okay yeah, -51'F is probably a reasonable minimum temperature to target for safe operation. Concern withdrawn.

Long time since the last update, but some things have happened since last time.

I took a road trip and picked up a rotisserie:

IMG_1795 by Fredrik Henriksson, on Flickr

I continued stripping the car:

IMG_1851 by Fredrik Henriksson, on Flickr

IMG_1871 by Fredrik Henriksson, on Flickr

Some wheels from a wrecked Saab had me trying on 17*8" with ET35. Does not fit.

IMG_1834 by Fredrik Henriksson, on Flickr

IMG_1829 by Fredrik Henriksson, on Flickr

IMG_1827 by Fredrik Henriksson, on Flickr

And I picked up front calipers from a Citroën minivan. Four-piston, magnesium goodness.

IMG_1868 by Fredrik Henriksson, on Flickr

There's a lot left to do, but progress is there. The next is to remove the engine and gearbox, get the car up on the rotisserie and start rust removal, asphalt removal and working on the fenders which needs to be flared all round. For the rear, I'm looking at modifying some replica Impreza WRC flares and for the front it'll be custom built full fiberglass or carbon wings.

Regarding the engine, I'm looking at getting some Ebay turbo and aiming for 250hp (shouldn't be a problem, these engines are bullet proof), but how do I dimension the turbocharger so I won't choke it or get massive lag?

Watching this with interest!

I believe the usual process is something like "Did the factory turbo my car's engine, and did their approach work for my intended goals?" If the answer is "No," the next question is "Is there an active, reputable forum dedicated to my car, with a decent signal to noise ratio and a section about turbocharging?" If the answer is still "No" (and I'm kind of assuming it will be for a Xantia track car project), then you're doing the right thing, which is posting on GRM.

As an experiment, I Googled "calculate size of turbocharger," and I got a page full of decent links. Bring a calculator and a scratch pad, and plunge into the math. Once you know roughly what you're looking for, I expect this forum can point you toward junkyard options that will be close. The next part of the fun is finding out what's common in Swedish junkyards vs. the ones we typically wander through.

How didn't I think of googling in English, I'm ashamed of myself ... I blame it on "This is just a hobby, I don't need to think".

I grabbed my pens and went to the Garrett homepage, and worked both with the equations and the Boost Advicer app.

With the equations, I went for:

*Power target: 275 horsepower (in spirit with always getting a little bit out of hand)

*AFR: 22

*BSFC: 0.38

*T_m: 130 degrees Fahrenheit

*VE: 98%

*N: 6000 rpm

*V_d: 122 ci (2.0 liters)

With these numbers, I end up with Wa of 38.3 lb/min and pressure ratio of 2.02. This seems to be out of range for many turbos, I think the air flow is too high compared to the pressure ratio. But is there something in my numbers that seems off?

With the Boost Advicer, I went for 250hp and mid range 3000rpm / top range 6000 rpm. This gave me:

Turbo_suggestion_by_garrett by Fredrik Henriksson, on Flickr

And, "No turbochargers fit your application". I guess that I have messed something up, but what?

I've always wanted a Citroen, you sir, are my hero. I'm watching this thread.

DrBoost wrote: I've always wanted a Citroen, you sir, are my hero. I'm watching this thread.

You never get "a Citroen", they seem to gather in hordes. I have three:

IMG_1839 by Fredrik Henriksson, on Flickr

IMG_1676 by Fredrik Henriksson, on Flickr

Sooo ... Be careful what you wish for ;)

I read through the thread again to see that you have a 2.0 engine. The Wikipedia article states that this engine was turbocharged by the factory. What turbo did the factory use?

I went through the really basic web "turbo picker" on Honeywell's website and it kicked this out; https://www.turbobygarrett.com/turbobygarrett/turbocharger#GT2056

Freddie wrote: And I picked up front calipers from a Citroën minivan. Four-piston, magnesium goodness. IMG_1868 by Fredrik Henriksson, on Flickr

Most awesome minivan calipers ever.

pres589 wrote: I read through the thread again to see that you have a 2.0 engine. The Wikipedia article states that this engine was turbocharged by the factory. What turbo did the factory use? I went through the really basic web "turbo picker" on Honeywell's website and it kicked this out; https://www.turbobygarrett.com/turbobygarrett/turbocharger#GT2056

Yes, the engine is turbocharged from factory. My car bears the TCT mark which stands for "Turbo Constant Torque". The stock turbocharger is, from what I can identify, a Garrett 454162-5002S and gives (along with a very lazy engine in general) these curves in blue:

XU10ochXU9kurvor_2 by Fredrik Henriksson, on Flickr