[Update on the Chimaera 400HC]

Keith Rothery recently gathered together a collection of TVRs and headed down to Progress Engineering in Kent for a day looking at power outputs and tweaking engines.

Keith reports:

The day got off to a good start with one participant running out of fuel on the M20, while yours truly broke down with the loss of a rotor arm, again on the M20, but I hasten to add not in my Tasmin. Dan Myers in his Chimera 400 performed the super hero duties and got some petrol for the empty S2, while the Progress Engineering boss, Nick Law, came to my rescue. On arrival there were already four Chimeras, one Griffith, a V8S, and a Cerbera, all waiting in eager anticipation of the days action. After the introductions and the admin duties of registering everybody, a running order was formed based on a first come, first whoever wanted to go first, type basis.

I would just like to point out here, that the BHP figures given below are those at the rear wheels, and not the figures we all read in the magazines, which invariably state the manufacturers BHP figures at the flywheel. It’s easy to over look the fact that there is an overall power loss in the region of 25% through the transmission. Also bear in mind that figures vary from rolling road to rolling road as they are rarely calibrated to absolute values, normally being used for before and after comparisons.

Onto the Roller

The Progress Engineering technician, Simon Crook, who was running the power checks had to perform the following procedure for each car:

• Discuss car and owners requirements, as stated on the registration form.
• Drive car onto rollers & hook up to the Diagnostic Equipment.
• Locate timing marks (not always easy due to the front of the car covered in road dirt etc).
• Take notes on initial settings.
• Select 1^st and nice and easy up to 4^th.
• Once in 4^{th………….}"Large it on the Loud Pedal".
• Observe the owners request of max RPM (in most cases between 5000rpm & 6000rpm).

First up for the power check was Graham Tuson with his Chimera 400 which posted 152bhp. Next up was Mark Elston in the only Griffith of the day, and a 5.0 litre to boot, which and was the first to break the 200 barrier with a screaming 201bhp.

There’s nothing quite like listening to the re-assuring "burble" of the familiar V8 as is goes up the scale. The sound of "blub blup blup" up to 4500rpm, which then takes on a harsher note of a roar at 5000rpm, then goes up a pitch at 5500 into an awesome metallic scream at 6000rpm. Magic!

Next up was Graham Ingleby with that outrageous exhaust on his Chimera 400 which posted 163bhp. Then came Dan Myers in his Chimera 400, which notched up 156bhp. Up stepped Den Lyon with his very bright yellow (ex-press car) Chimera 450, and topped out at 184bhp. The first S series car was next, with Simon Houldsworth in his 3.9 V8S, and obtained 170bhp.

AJP V8

Then in came Richard Prebble in one of the new generation cars, a bright raspberry Cerbera 4.2 AJP V8. This V8 does not burble, it sort of punches the exhaust note out the system with a dry, hollow sound, which is due to its "flat plane racing crank". Once on the rollers it was not possible to hook up the diagnostic equipment as there are no visible electrics, even after removing the top engine bay cowling, therefore Richard would just have to settle for bhp figures only, which by now, absolutely everyone was watching for with serious interest.

The traditional V8 had sounded good, but this was different…….as the revs got higher the atmosphere got tenser…..and the sound got meaner. The figures started spinning…..200 – 210 – 220 – 225 … then it got louder…….meaner…….aggressive even …………and still the figures went higher 230 - 235 – 240 – 245 by now both the engine / exhaust were barking……249 @ 6000 rpm……....just T.F.M.

Afterwards Simon stated that the BHP was still climbing but he had decided to stop at 6000 RPM just to be on the safe side.

In order to give Simon a break from the rollers, Nick performed a practical demonstration on how to balance a V8 crank. Unfortunately they didn’t have an engine on the dyno bench, but there were various diagnostic print-outs of previous engine runs, including several 4.5 V8’s, a few race prepared 4.5 V8’s, and even a couple of Ferrari V8’s.

Wedge

Back onto the power checks, and this time a Tasmin joined the fray, with Jonathan Cirkel (Cirks) and his 450SE, which despite running extremely lean at the top end (as diagnosed by the equipment), still managed to produce 190bhp.

Then came Trefor Jones with his Chimera 400 and laid down a 161bhp. Next up was Ed Horne in his S2 2.9 V6. Ed was concerned that his V6 was not running correctly due to recent adjustments to get it through the MOT. Simon and the other mechanics hooked it up to the diagnostic equipment and soon had it running as a 2.9 should be. Onto the power run and the V6 checked out at 110 BHP.

400SE

Back to the Tasmins with Jason "Large Bore 4-inches of Tail Pipe" Vaughan in his 400SE, once again despite running very lean at the top end, managed to post 154bhp.

Speed Six

In came the second of the new generation engines, Steve Jenkins and his Cerbera Speed 6. Once again everyone’s concentration became more focused, as yet another different engine note started up. The figures started spinning 180 – 190 – 200- 210- 220 – 230 @ 6000 rpm. Superb.

Cerbera Speed Six

Last in was Ian Collins in his Chimera 400HC. Here was a little battle brewing. Trefor Jones and Ian work together, so it was a case of…."Mine’s Bigger Than Yours…" The familiar V8 burble started and once again all eyes were on the figures, 80 – 100 – 110 – 121…and the car is shut down. Ian does not look happy. Simon gets out of the car shaking his head and calls Ian over. A brief consultation with Nick and the mechanics followed by some under the bonnet adjustments.

Fire up the Chimera again and off on another run……80 – 100 – 110 – 120 – 130 – 140 – 144… and the car is shut down again. This time Ian looks happier but Simon is not. Further discussions with Nick and Ian. The mechanics dive under the bonnet and make further adjustments. Ian still wants another run, even though the car is getting a bit warm. In jumps Simon, all eyes are on the figures…..80 – 100 – 110 – 120 – 130 – 140 – 150 – 161…..Ian is beaming from ear-to-ear…..can’t believe it……from 121 to 161 a 40bhp increase in power, excellent work from the mechanics. [Update]

To summarise the day we had an excellent cross section of models - S2, V8S, Tasmin, Chimera, Griffith, Cerbera - what was outstandingly apparent was that TVR's new generation of engines in the Cerbera’s are a major evolutionary step forward from the Tasmin/Griffith/Chimera. The pre-cat Tasmins held their own with the Griffith & Chimeras, and most important of all everyone had a great day.

I would personally like to thank everyone who turned up and a special thanks to Progress Engineering for staging the event, who did say afterwards that they would be more than willing to repeat the event in the new year.

Results

* These are not absolute figures

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Update

Ian's Chimaera 400HC exhibited a large power gain when tweaked on the rolling road, which obviously required an explanation.

A new camshaft had been fitted in the months before and the timing had been set incorrectly. After adjusting the timing there was 161bhp at the wheels, which is around 200 'real' bhp at the wheels.