Fiat Uno Turbo Sprint Car

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uno_turbo
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Joined: August 3rd, 2006, 1:59 am
Location: USA
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Fiat Uno Turbo Sprint Car

Post by uno_turbo »

Fiat Uno Turbo Sprint Car

As requested by Guy the following is a write up about my Fiat Uno Turbo Sprint/Hillclimb car.

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Goal:

To produce a competitive sprint/hillclimb car for the modified production class in the 1401-2000cc category. Unlike the other competitors the car would remain fully road legal and be driven not trailored to events. Modified Production class has the most free regulations for car modifications. Any car originally built for the road can compete. Typical cars racing would be; Mk1 & 2 Ford Escort's, Peugeot 205's, Lotus Elan's, Alfa Romeo Sprint's, BWM 2002's.

The project began in 2002 after two competitive seasons sprinting my normal road car in the standard class (very limited modifications allowed), an Alfa Romeo 145 2.0. I wanted a faster car and set about thinking what car would be the most competitive for the budget. I came to the conclusion of using the Uno Turbo as a base car because of my affliction for Italian cars and the potential of a turbocharged engine. Note: turbo charged cars run under an equivalency formula (multiple capacity by 1.4) so you would compete against normally aspirated cars of larger capacity.

The car was re-shelled as the donor turbo car was too rusty to resurrect. Modifications to practically all elements of the car were completed; engine, chassis, brakes, wheels, tyres, aerodynamics, electrics, interior trim, etc.

From now on I will concentrate on the engine modifications for the purpose of this Guy Croft article.

The engine was stripped down and then transported to Guy where the following modifications were completed:

Race spark plugs
Re-bored to 1423cc with wire ring conversion
Forged pistons
Cylinder head work
Triple race valve springs
Lightened flywheel
Modified oil ways
Baffled sump with Accusump

Guy re-assembled the engine and I went back and picked it up a few weeks later.

The engine modifications were finished off with a hybrid T25 turbo from Turbo Technics with -10 impeller and .48 turbine housing, a Group N straight though rally exhaust, adjustable fuel pressure regulator, larger fuel pump, much larger intercooler (over double size), 12 row oil cooler with remote filter, Bosch 165 L/hr @ 5 bar fuel pump and a K&N filter with two cold air feeds. The down pipe was threaded so a lambda probe could be inserted to monitor the fuelling.

This was going to be the initial phase of the engine modifications with a fully mapable engine management system to be added at a later date. The thought was if the car was reasonably successful in this form it would have a much greater potential if the ignition timing and fuelling could be setup properly.

With all the modifications the car would clearly need more fuel supplied to the engine to balance with the extra air being forced through the engine. This is where the up-rated fuel pump and adjustable fuel pressure regulator came to use. The standard fuelling system (hoses and connectors) is rated to much higher tolerance pressures than what it normally runs at. What was determined as the weakest joint was bench tested to breaking tolerance to check this assumption.

I stuck with the original injectors as under higher pressure they would produce a better spray pattern, larger injectors were tried (From a Punto GT) but the fuelling could not be adjusted sufficiently for the car to run well at low and high revs and throttle positions.

The fuelling was checked with a wide band lambda probe and a data logger allowing the data to be downloaded to a laptop for analysis. I actually ran with the laptop in the car along side and monitored the fuelling starting off in 3rd gear and accelerating to the rev limiter with marker lines every 500 rpm. The aim was to have the mix at 12:1 at max boost. I continued turning up the boost pressure and fuel pressure ensuring to keep the mix around 12:1. I reached 1.5/1.6 bar boost pressure and the fuel pressure was running at about 7 bar maximum ¢‚¬Å“ I had added a fuel pressure gauge in car to monitor this. The above was done over some time until I was happy the engine was running ok at high boost pressures.

At high loads the fuelling was acceptable but at low revs it was very rich, this was due to the adjusted high fuel pressure. This caused some problems if the engine was run cold with the race plugs, they would soot up and then the car would cut out and not start. This problem was worked around by running a high idle (about 1000-1500rpm) and also warming up the engine for 10-15 minutes before any driving commenced.
After the boost and fuel changes the car was now accelerating pretty quickly! At only 840 KG's with somewhere in the region of 170-190 bhp.

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As you can see from the graphs the fueling was far from perfect as sometimes it would be acceptable over the entire run and sometimes it would run incredibly rich at low revs. However as the car was only run at high loads and revs on the track this wasn't too much of a problem.

During this time the rest of the car was setup, camber, toe in, anti-roll bar, etc and then tested on the track. It was taken to Goodwood and flying laps commenced, it quickly proved to be pretty quick although there were areas to be improved and the necessary steps taken. The eventual fastest flying lap was a 1:31.44s Note a Lamborghini Murcielago had only lapped 3 seconds quicker on an Autocar magazine test! So it was certainly punching above its weight.

GOODWOOD AUTOCAR TEST DATA August 2001
Lamborghini Murcielargo 1.28.60
Westfield XTR2 1.29.08
Caterham R300 1.29.34
Porsche 996 C2 1.30.31
Mercedes SL 55 AMG 1.30.60
Ferrari 575 m F1 1.30.88
TVR Tamora 1.31.50
Honda NSX 1.31.85
Ford Focus RS 1.33.89
Porsche Boxster 1.34.17
Lotus Elise 111S 1.35.73
Subaru STI Pro- drive 1.35.82
Alfa Romeo 156 GTA 1.36.60

The car was taken to many sprints and hill climbs over two seasons and won some class victories with an array of 2nd, 3rd and 4th places too. One of the most outstanding achievements was the 2nd fastest overall lap in the wet at Goodwood, this was out off all classes including single seater Formula Renualt, Clubman and sports racing type cars. It was very controllable in the wet especially with left foot braking the understeer was very easily controlled.

Future modifications to the car were to be continuation of lightening, more aerodynamic modifications (under tray and side skirts), limited slip differential, and the fitting of a programmable engine management system. Unfortunately the car never got to this stage after a costly mistake put the car into the tyre wall at Goodwood making a mess of the shell and requiring another rebuild. That was now over two years ago and the car is still not complete although I have left the car with my father to complete the modifications which I am told is now progressing well.

I'd like to thank Guy for his skill and advice with the engine modifications, my father for all the work he did on the car (most of it!) and my mother for putting up with all the time he spent in the garage!

Nathan Corridon

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Click to watch short Goodwood video *

* in WMV - windows media player format only
Last edited by uno_turbo on March 17th, 2008, 8:00 am, edited 2 times in total.
Guy Croft
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Post by Guy Croft »

Model Post!

Impressive in the detail and beautifully written - by someone who has real-time experience.

Well done Nathan and thanks! This is exactly what GCRE.com exists for.

GC
WasteGate
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Location: Cape Town, S. Africa (A)
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Post by WasteGate »

Hi Nathan,

You have a nice car, cool!!!
I also own an series 2 Uno Turbo (1372 cc) where the turbo has been replaced with a TD04-15T . The injectors have been upgraded to 280 cc/min and power output is up to 122 kw @ 6300 RPM and torque to 216 Nm @ 4800 RPM.
Boost applied is 1.2 bar. The airflow meter has been recalibrated for the bigger injectors and the standard Marelli ignition is retained. Apart from a racing air filter the rest of the engine is stock standard.

The whole purpose of this setup was to to have a car running on pump fuel only and which is easy to drive for daily use and reasonable economics and durability. I must say I like the package as it is although I was toying with the idea to fit a Megasquirt system (not that it is needed though).

It would be interesting to know the suspension setup you used on your Uno as we all know this is an area which needs a lot of improvement on this little car, especially on the traction side of things.
biz
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Joined: July 26th, 2006, 12:36 pm
Location: South London
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Post by biz »

Such a well spec'd Uno :!:

yes im intrested too about the suspension and tyre combo you used to get a 1:31 at goodwood!

I mean to be 2 seconds from a Caterham i would love to know what you use! lol
uno_turbo
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Joined: August 3rd, 2006, 1:59 am
Location: USA
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Post by uno_turbo »

It's been a while but I checked on this page and saw the replies. In answer to the questions I¢ž¢ve been asked;

The suspension was setup with Avo adjustable front struts and a custom system on the rear to accommodate harder springs. The front struts were also modified to allow camber changes. Poly bushes were used as well as an adjustable anti-roll bar on the rear, this was more a stiffening bar for the rear beam than an anti-roll bar but still had a good effect.

The front splitter was produced by using two Uno bumpers and joining them together, you can see if you look closely at the pictures. The front splitter is made from ply wood as are the dive plates.

The car is almost ready now, we are aiming for an October finish in time to take it out on the track and shake it down before trying to sell it.

I will add some new photos soon of the suspension setup to give an idea of how this was achieved.
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