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Saturday, 26 March 2016

Jack Neal Memorial Rally 2016 | Blyton Park

During the winter months, Lotusbits entered both Lotus Sunbeams, supported by DTA in the Motorsport News Circuit Rally Championship.
The new series, in association with MSVR, has launched with an exciting eight round provisional calendar for its inaugural season.
Here's a few shots from the recent 2016 Jack Neal Memorial Rally, in which Mike and co-driver Louise Gilks finished 2nd in Class and 8th overall.
Cathy and co-driver Colin Stephens finished 4th in class and 21st overall - from an entry list of 66 competitors.

DTA designs and manufactures engine management systems for spark ignition engines intended for use in competition vehicles. All their systems are designed to be fitted to almost any engine and are easily mapped. They're very competitively priced too!
Engine management systems

Friday, 25 March 2016

A Jensen Gets the Excel Touch...

The Jensen GT was, alongside the Jensen Coupe, the last model that Jensen Motors built before the West Bromwich factory closed down in 1976.  The GT was a “shooting brake” version of the Jensen-Healey, carrying over the Lotus 907 engine, the Getrag 235/5 gearbox from the BMW2002tii, suspension / live axle from the Vauxhall Magnum, and the love-it-or-hate-it styling of the Healey, but with a more upmarket Interceptor-type interior.  511 GTs were made, of which over half went to the States, before Jensen went bust, leaving many unfulfilled customer orders.  Only 12 are left on the road in the UK today (Q1 2015 figure).
I bought my GT in May 2014.  It had just come to the end of a 20-year two-owner restoration.  Bodily it was in very good shape, and it seemed mechanically sound.  In the six months after buying the car, I sorted out some residual electrical issues and got everything working, changed all the weather seals, and replaced some worn suspension parts.  The car was fun to drive on winding roads, but very tiring on dual carriageways, because the 1:1 5th gear of the Getrag gearbox meant high revs at cruising speeds and a very noisy engine and exhaust.  I unsuccessfully investigated various options to drop the revs, including standalone overdrive units and finding a similar dogleg pattern gearbox with a proper overdrive 5th gear (the ZF S5-18 is the only one).

I had read Mike’s “Improving your Lotus” presentation on the website, and Lotusbits’ work had been recommended by a fellow GT owner.  After my son told me that my GT “made a lot of noise when I put my foot down but didn’t actually go any faster”, I called Mike to ask him to price up an engine upgrade to Lotus spec 5.  Mike suggested it would be better to go for a fuller upgrade to spec 10, and also suggested I get the Toyota W58 gearbox installed.  I agreed to the spec 10 upgrade and the Lotusbits large bore exhaust system, but reserved judgement on the gearbox swap.  The mandate was fairly straightforward – more power, less noise, and keep the car looking as original as possible.

In early February 2015, I drove the GT up the Fosse Way to Lotusbits.  The pre-upgrade dyno run confirmed that my GT was down on power – 119bhp peak (and 116 lb-ft of torque) compared to 140bhp (130 lb-ft) for a Jensen spec 907 engine in good condition.  Mike also found that the clutch had not been properly installed, and that the gearbox input shaft had been damaged as a result.  Given the lack of Getrag specialists in the UK and the likely cost of repair, I agreed with Mike that the Toyota gearbox upgrade was the way to go.  Mike also noted the car’s lean to the driver’s side, which he thought might be a bent chassis.  At this stage, my heart was really sinking.
Engine Bay Before and After – The Lotus Excel Airbox Setup which Unleashes the Horses
There then followed what seemed like an interminable wait for the engine to come back from Mike’s engine builder.  Actually, the hold-up was partly my fault – I had insisted on keeping the original cam carriers and cam covers (the ones that leak oil) and it took ages for the cam covers to come back from the powder coaters.  We also found that the car had been fitted with three 9.5:1 CR pistons, and one 8.0:1 CR piston.  Potentially an expensive disaster waiting to happen.  Towards the end of April, the engine finally came back to Lotusbits, and Mike told me progress would speed up.  Neither of us had, however, counted upon the time and effort to resolve a previous poor repair of one of the chassis rail suspension mountings, or to fettle the gear lever to fit the transmission tunnel.  It’s always the smaller jobs that take the longest.
Retaining the Original Jensen Look – The Lotusbits Large Bore Exhaust System is on the right
Finally, at the end of July 2015, with the GT MOT’d and works nearly completed, it went back to Northampton Motorsport for its post upgrade dyno run.  Mike called me at work, rather sheepishly, to tell me that peak power was now 155bhp, or 174bhp without any airbox and filter.  This was pretty disappointing, as both of us had been expecting somewhere north of 180bhp.  Mike suggested fitting the airbox setup from the earlier Lotus Excel.  I agreed, on the basis that something similar had been fitted to the last GTs (actually the Elite / Eclat airbox went into the last Stromberg carb T75 Jensen GTs).

A few days later, and another dyno run gave the figures we were both expecting – 184bhp peak and 167 lb-ft, a 50% increase over the pre-upgrade figures.  A week later, Mike dropped off the car and I drove it for the first time in 6 months.  It was transformed – much quieter at lower revs, but when I put my foot down it pulled like a train and gave off a pleasingly throaty 4-cylinder rasp.  It now cruises comfortably at 70mph and 2,900 rpm as well.  
Dyno Run Comparison – Before Upgrade in Black, After Upgrade in Red
A few days after getting the car back, I took it to the UK’s resident Jensen GT expert, and he confirmed what I already knew – I now have the nicest driving GT around.  Perhaps, if Jensen had managed to stay solvent, the GT would have benefited from Lotus’ development of the 907 engine through to 912 HC spec, and it would have ended up like mine.  We’ll never know.  I just like to think that my GT is now the “baby Interceptor” that Jensen always meant it to be, courtesy of Mike and the Lotusbits team.
© Kindly written by: Nigel Kieser - proud owner of NUY 903P 
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