The first proper run out

We've done a few trips out in the car but since finishing all the mechanical work and getting the car set-up on a rolling road we'd not been out for a proper drive. So on a hot sunny Sunday morning and with a friend's VX220 for company I went out for a morning's drive.

The route we took was a familiar one, A34 down to Alderley Edge, B5087 to Macclesfield, A537 up to the Cat & Fiddle Inn, then back down the A54 to Congleton. For the first time the drive out would allow us to understand how the car performed against another car and see if it behaved itself on a longer drive out.

The other car was a standard VX220 N/A which has 145 bhp, but weighing only 875kg means it has 168 bhp/ton. From a standing start the VX had a lot more low down power and the Renault appeared to be slightly sluggish in comparison, it really was apparent that if not kept above 3,500 - 4,000 rpm the Renault could not keep up with power delivery in the VX. However when the Renault was up to speed and on a twisty road and kept in the desired rev range it could easily hold it's own. In the corners the VX handled slightly better but accelerating out of the corners the Renault could pull away. It was a pretty even match with each car exploiting its strengths on each of the roads we went down.

One other thing to remember when comparing cars is that turbo cars, especially turbo cars with a large turbo and small engines can be laggy.  Driving against a normally aspirated car on the road - means we will have to thrash it to make our power work.  As already stated this is tricky to do on public roads. However on track this is much less of an issue, we are far more likely to keep our car in the power band and keep the lag to a minimum, but ultimately we will find out on the track.

Picture of the TrackBitch on A537 - Cat & Fiddle

The triangle of roads we use can be pretty busy on a Sunday however we seemed to get lucky, particularly on the final stretch towards Congleton, with no traffic on large sections of the road.

The car can be quite savage when on boost and you have to be quite careful not to mash the throttle as it can lead to the wheels spinning up (maybe some better rubber can assist with some of this). The car now handles a lot better since we have restored the axle back to its original ride height and added the GAZ adjustable shocks, however I still need to build up the confidence with the cars limitations, something I don't want to be doing on public roads. As mentioned previously it is critical to keep the car on boost and any incorrect gear changes will lead to the car bogging down and not being able to get back up to speed as quick as you might like.

Picture of the TrackBitch on A54 (note the average speed cameras now on the road)

On the trip out a couple of people even passed positive comments when seeing the car, a nod of appreciation from a biker and complements from an Audi owner who use to own one himself.

Overall the car performed very well and we're now confident that it should not embarrass itself on its first track day. We've booked Cadwell Park on Wednesday 3rd August  so we'll soon find out.

Setting the car up - an update.

The car was now setup and ready for it's first track day, however there was something that we thought was not quite right, the bhp we were producing seemed a little low. Whilst 157 bhp was a good performance gain and is still a lot of fun to drive, we were hoping for about another 10 - 15 bhp more from our set-up. This led one of the more mechanical owners of TrackBitch to head to the forums and enquire about what we have got, with some interesting responses.

We had measured the boost pressure from the carb top whilst most owners of Renault 5 GTT measure them from the carb base as you lose 4-5 psi through the carb itself and it gives a more accurate reading as to what the engine is actually getting. This could mean the car has even more potential than we think. See some thoughts below:-


With regards to BHP
Our rolling road said - 143bhp at the wheels but calculated 157.6 bhp at the flywheel. When the rolling road calculated flywheel BHP at the start he calculated a drive train loss of around 20%. For some unknown reason once tuned he calculated a drive train loss of about 10% - which is physically impossible. Drive train loss is much more consistent, if anything it is more at low power NOT less, in his calculations for us drive train loss changed and was FAR more at high power?

Talking to the guys on RTOC.org and using a 2wd loss calculator on line it is FAR MORE likely that our flywheel power is now 170bhp.  You can do the same by entering your drive train type (front, rear or 4 wheel drive) and wheel HP here
http://www.dyno-power-run.com/dynocalc.shtml

If you enter fwd and 143 whp in to this calc it gives our car a maximum 170bhp and a power to weight of 205bhp per tonne. We still have the option to safely add about 3 psi of boost (due to setting up at around 15psi carb base instead of 18psi carb base).

So we can probably expect 180+ bhp in the near future.

Ultimately what really matters is wheel horse power - torque at the wheels is the only accurate measurement a rolling road can offer, but as manufacturers use flywheel horse power (because they dyno their engines on a bench not in the car) then we have used flywheel bhp for comparison to other cars.

Lastly, we don't think we have a lazy turbo - we think at high boost (20psi +) we may well have a boost leak, probably at the wastegate, due to wastegate creep (probably caused by our poorly T3 actuator - which has no adjustment in it) or a possible leak elsewhere in the boost pipe work or the inter-cooler.


The full posting can be read on RTOC but you'll need to sign in to read it.

Setting the car up - A job for a professional & a rolling road

We all decided that we should get the car set-up properly, plus if set-up on a rolling road then we would finally find out what we had under the bonnet. Finding places that have rolling roads is quite easy, however finding places that have rolling roads and can set a car up that has a carburettor is a little harder to find. After an afternoon of internet searching and numerous phonecalls, one member of Team TrackBitch found Ric Wood Motorsport in Stockport, we asked if he could set it up on the following Saturday, but were told it was not possible as he was at Oulton Park assisting the touring car teams for BTCC. Nothing but the best for the TrackBitch.

The car was booked in for the following week and we all placed bets on what bhp we would achieve. I was hoping for around 175bhp, other team members whilst hoping for that sort of figure thought around 160bhp maybe closer to the mark. Setup wasn't cheap either at £150 per hour but it is worth doing a proper job. The car was the last one to be worked on that day, so we had an impatient day waiting to find out. After a couple of hours the car was done, interestingly the car was running lean, when we thought it was running rich, so probably a good job it was set-up by a professional.

So, onto the important bit, the figures....

Starting figures
Maximum Power - Wheels - 105.0 bhp @ 5,510 rpm
Maximum Power - Engine - 125.2 bhp @ 5,500 rpm
Maximum Torque - 128 lbft @ 4,206 rpm

Out of the factory they were 118bhp so we started in a favourable position.

Finishing figures
Maximum Power - Wheels - 143 bhp @ 5,133 rpm
Maximum Power - Engine - 157.6 bhp @ 6,204 rpm
Maximum Torque - 166.4 lbft @ 4,803 rpm

So we'd not quite made the 175 bhp we were after, Ric did say that our Turbo seemed a little weak, which was a bit worrying but that is probably what you get when you have a little gamble on eBay.

Picture below shows print out from the day.

So we didn't quite make what we were hoping for, however the car now feels so much different, the turbo when it kicks in is quite savage (easy to wheel spin in second in the dry) and if you keep the power above 3,500 rpm you can get from A to B pretty quickly. Clearly it is not a car for 0-60 times but on track driven correctly we are hoping to trouble some more serious hardware.

Looking at bhp per ton figures and using the performance calculator on Letstorquebhp this gives us:-

158bhp
831kg
Power to weight of 193bhp


To compare this, listed below are a few bhp per ton figures for some hot hatches.

Standard Renault 5 GTT - 146 bhp/ton
Honda Civic Type R - 158 bhp/ton
Mini Cooper S Works - 170 bhp/ton
Renault Clio 182 Cup - 168 bhp/ton
Renault Megane R26R - 189 bhp/ton
VW Golf R - 178 bhp/ton
Ford Focus RS - 208 bhp/ton

So, new turbo fitted, new rear axle, new rear suspension and a rolling road set-up. Let the fun commence.

There has been a further update since this was written. Please read - Setting the car up - an update