Author: matthewpoxon

180° Crossover Equal Length Manifolds

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Most TVR owners will be familiar with Clive Ford’s stainless master pieces in the form of his popular manifold Y Piece. Last year Clive surpassed himself and created a tuned crossover manifold system, the same design as seen on the legendary Le Mans winning Ford GT40 that somehow fits under the bonnet of a Griff.

So what is the point of a crossover manifold? The issue with a conventional 4-1 exhaust header is the separation between exhaust impulses. With a 90° (cross plane) crankshaft 2 exhaust pulses exit through the collector at the same time. A crossover manifold pairs the correct cylinders that fire 180° degrees apart in their firing are paired together, maximizing scavenging. When one cylinder is on the compression stroke, the other is on the exhaust stroke resulting in a constant flow, thus creating equally spaced exhaust pulses.The result is similar to that of a 180° (flat plane) crankshaft with four evenly spaced exhaust pulses in each header.

I had managed to resist the temptation of Clive’s latest masterpiece until I bumped into fellow Griff owner Peter Billington at the Griff Growl last year. Peter has a immaculate, sensibly modified Griffith and had just completed fitting the crossover manifold system. Peter very kindly offered to take me out for a spin in his to demonstrate the new manifolds and I was sold. The sound was incredible, a cross between a RV8 and Cerebra with the howl of a GT40 higher up the rev range…. epic! A few weeks later Clive received an order.

I am still running the OEM Lucas 14CUX ECU on my Griffith. I asked Clive to build the manifolds with two narrowband lambda sensor bosses (one per bank)  for the 14CUX and two wideband lambda sensor bosses for a future expansion (aftermarket ECU). I also asked for a wideband lambda sensor to fitted where both banks merge to allow me to run an AFR gauge at a later date.

Running the 14CUX with this system does pose an issue in that the lambda sensors in standard configuration read from  cylinders 2,4,6 and 8, and 1,3,5 and 7. With the crossover manifolds fitted the sensors read cylinders 1, 4, 6 and 7, and 2,3,5 and 8. The 14CUX is bank fired so to correct this it is a simple case of extending the injector wiring so injector wires 3 and 5 are swapped for 4 and 6.

Changing manifolds on a TVR is always a time consuming job due to the lack of access to the bolts. 2 long evening later the manifolds were fitted. The water pipe to the radiator was rerouted underneath the chassis rail and I took the opportunity to fit a JE alternator bracket to replace the tensioner.

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First impressions are very good. The car seems to rev much more freely and the sound is epic. Below is a quick test on a cold day in February with new tyres so not going too mad. I will record a better video soon…

The car is going up to Dom at TVR Power for a service in March and will be going on the dyno to check the AFRs are correct. I will post the dyno result once I have it.

 

Snetterton 300 Track Day

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Another Snetterton track day organised by fellow TVR Pistonheaders. One of my favourite tracks as it is less than 2 hours away from where I live and it suits the Griff being a power track with long straights.

The circuit for the track day was the full 3mile ‘300’ circuit which includes 2 fast straights and a number of more technical areas.
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The noise limit for the day was 105dB static. Last year I just sneaked through the limit without the need for any additional cans. This year the same, the car was measured as 104dB much to the surprise of the MSV staff. On track unfortunately I I was black flagged as I breached the driveway noise limit and was required to don the ACT bolt on silencers.

The weather forecast was grim but the rain did not come in the quantity that was forecast so for the most part the track was dry. The TVR performed impeccably.

As per usual my trusty GoPro was on hand, unfortunately MSV deemed that the official 3M GoPro mount was no longer allowed for trackdays and all cameras needed to be mechanically mounted so I was not allowed to run with the camera on the front of the car.

I was also running Harry’s Lap Timer app on my iPhone, not for competitive lap timing as this is not allowed but for video telemetry overlay on my personal videos.

I have also invested in a Racelogic VBox Sport to use with Harry’s Lap Timer as the iPhone internal 1Hz GPS sensor proved did not seem to adequately keep up with the video before. The Racelogic VBox has a 20hz GPS sensor and pair with the iPhone using bluetooth. You can see it Gaffer taped to the dashboard in the video.

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My best lap of the day was 2:24.66 at an average speed of 73.8MPH which I was happy with.

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TVR Power Dyno Run

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I booked the Griff in with Powers Performance (TVR Power) for a dyno run following my last visit to the drag strip for PH Sunday service. My 1/4 PB is 13.202 a couple of years ago, I have since changed the standard cam for a TVR Power 885 cam and the road tyres have been swapped for AD08Rs.

Sunday service was great fun but I could not get any faster than a 13.5 and my terminal speed was down from 107 to 104. My assumption was the car had lost a bit of power somewhere so I booked the car in with Jason at TVR Power.

To my suprise the car was up from 242.8BHP on the original TVR435 cam to 275.1BHP on the TVR Power 885 cam. Torque also looking more healthy up from 278 to 295. Clearly no horses have bolted the stable so clearly down to the driver :-/ perhaps I have lost some driver XP

TVR Power dyno reads in wheel BHP so I have converted to flywheel using the below site
http://www.mk5cortinaestate.co.uk/calculator4.php

BHP – 324BHP
Torque – 348ftlb

A huge thank you to Dom and Jason at TVR Power not only for accommodating me a short notice; despite using up over 2 hours of Jasons time and using the dyno cell Dom refused to take any money from me. A very kind gesture and I am most grateful.

 

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Jason showed me some of the work he has been doing with the MBE ECUs which I am now 100% set on getting fitted to mine. Really nice pieces of kit and used by the likes of Caterham, Noble and Harley Davidson so fully type approved and OEM quality. Mine randomly lost all power last weekend, a quick rummage in the foot well and order was restored I think I am on borrowed time with my loom, it has already been repaired twice at great expense, looking at the quality looms Jason makes up for the MBE systems I am convinced this is the way to go.

The Griff did well against the M5s at Sunday service:

What I cannot work out is if I have a mildly tuned 500 with 275BHP at the wheels, how does a completely standard 500 leave me for dead mid track onwards despite getting a good start?

In summary TVR Power = awesome. TVR Power 885 cam = awesome. Driver needs lessons. How the F*** is Dave’s Griff so quick?

T5 Gearbox S10 Tail Housing conversion

Before I begin I must mention David Byron to thank him for his assistance and guidance with this modification.

All TVRs from late Griffith onwards use the Borg Warner T5 gearbox. Griffith and Chimaera used an earlier tail housing for the T5 box which required an additional linkage to bring the shifter out in the correct place.

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On the later ‘T’ cars TVR used the S10 tail housing which presented the shifter in the correct place and did away with the additional linkage.

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The basis of this modification is to retrospectivily fit the later S10 tail housing to the T5 gearbox in my Griffith, thus deleting the additional TVR linkage and improving the feel of the gearbox. I also opted to complete a number of other small enhancements along the way.

John Reid at Readman Racing (Grantura Engineering) has been offering this upgrade for a while and supplies reconditioned S10 tail housings with a new top section with all new bushes and the new selector etc so that the two complete units can just be swapped straight over. From speaking to other owners who have completed the modification a new mount for the gearbox is required and also the TVR remote linkage offsets the gear lever by about 2 inches toward the driver so a dog leg needs to be introduced into the shifter to present it in the same position as before.

As part of the S10 package I also purchased a bronze shift cup and bronze shift forks to replace the standard plastic items again supplied by John Reid.

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I also opted for a replacement Hurst shifter with improved pre-loading to make shifting from 2nd to 3rd easier. I purchased a custom Hurst shifter from Core Shifters built specifically for S10 T5 boxes and with a custom fulcrum height designed for the 6 inch TVR stick.

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Finally I decided upon a custom Stainless Steel gear knob from Chris at Lathewerks in the USA. Machined from a solid block of steel and weighing in at 550G it is approximately 3 times heavier than the original TVR item and has a slightly bigger circumference.

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David Batty my TVR specialist has completed the modifications to the gearbox while changing the clutch and replacing the leaking rear main oil seal.

First impressions are good, it is now easier to select gears at the far end of the box (5th and reverse). The Hurst shifter has reduced the distance between the gears slightly and has a more positive self centering effect. I will update this once I have done over 1000 miles to get a feel for it.

1000 mile update – I have since completed a RWYB day at Santa Pod, a number of long 300+ journeys and a track day at the Lotus test track. I am pleased with the improvements to the gearbox and definitely worthwhile if the box is coming out anyway, I would personally not recommended spending the money on labour removing the box just to have this mod done. The difference is not night and day different just subtly improved.

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Cerbera Seats

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I have always found the original seats very comfortable but lacking in lateral support. Since I have been attending more track days I have struggled with the Griffith seats not only do they not hold me in very well but the seating position is a bit too high and my head touches the roof when wearing a helmet.

Having researched various options I note that popular options for replacing the original seats are Lotus Elise and Mazda MX5 which are both narrow enough to fit. Although the aftermarket options did look appealing in that they are much lighter and offer more support the replacement seats had to be a  ‘TVR’ seat for me to maintain as much originality as possible.

Tuscan seat test
A good friend of mine had a pair of Tuscan seats up for sale which I purchased. I ran this seat in the Griff for most of 2015 to test it out for comfort and also completed a number of track days. I found the Tuscan seat much more supportive than the originals and being able to take the centre cushion out for track days and sit even lower in the car and wedged in is fantastic.

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The issue with the Tuscan seat is for some reason even though the seats felt comfortable they gave me a back ache on long journeys. I also found the seats a bit too wide resulting in me being rattled around in them a bit on track. My main complaint with the seats is the lack of shoulder support, where the bolsters come up around the seat to form the headrest my shoulders sit on the bolsters which is not very comfortable. Lastly although I adore the design of the Tuscan seats I am not sure they entirely suit the Griffith.

Cerbera seat test
I have had a pair of Cerbera seats in the loft for a while now and since had tried them out before but found the seating position a bit too high (about 2cm higher than the standard seats). No good for me as I ideally need to be 2cm lower to accommodate the helmet on track days.

Taking what I had learnt from the Tuscan seats I decided to try out the Cerbera seats again.

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I instantly felt the Cerbera seats where more comfortable and I couple of long journeys confirmed no back ache. The shoulder support is good and the seats feel sculpted. The fact the last 100 Griffiths were fitted with these seats from the factory is a big plus for me as technically even though they were not fitted to my car they are an OEM part which did feature in the Griffith.

On the negative side the issue with the height was very apparent as soon as the seats were fitted, I was now sitting far too high, my head was very almost touching the roof without a helmet and the driving position overall not great due to the height. Leg support on the Tuscan seats was also far superior and the Cerbera seats felt a bit short in terms of length.

Knowing I would be getting the seats re-trimmed I decided to modify the bottom foam by removing 75% of the foam thickness from the main cushion but leaving the leg support intact to provide a better support similar to a bucket seat design. The result not pretty but provided a proof of concept. Height wise this was now almost perfect although the very thin layer of foam was not very comfortable at all and very cold. The leg support also worked very well indeed.

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Cerbera Seat modification and re trim
Throughout the testing phase of both seats I had been speaking with Dave The Trimmer who I had the car booked in for the seat re trim with. Dave in my experience is not only a very talented trimmer but is one of few individuals I spoke with who was happy to take on the challenge of potentially creating something bespoke.

Looking at the design of the Tuscan seat and the Cerbera seat I noted that one of the reasons the Tuscan seat is lower is because the Cerebra seat has a solid fibreglass base and the Tuscan seat has webbing.

Cerbera seat
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Tuscan seat
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I arranged to pop in to see Dave to discuss the possibility of modifying the Cerebra seat by cutting out the fiberglass and installing webbing. I also wanted to see if he could make a custom bottom foam based on my butchered original. With the scope of the seat retrim works clearly transforming from a few modifications into more of a complete custom build at this point I was expecting a lot of back tracking and excuses but the answer to both questions was simply “Yeah I can do that”.

The Griff went in with Dave the Trimmer on the 1st February. 1 week later Dave had modified the original seats and was ready to mock up the test foams.

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I also asked Dave to replace the rear seat foams to provide additional comfort. Below the seat can be seen with a prototype bottom foam.

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A couple of weeks later the custom made foams were ready. Below picture shows the new custom foam (left) original prototype (centre) and the original OEM foam (right)

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A week later the seats are finished complete with heated seat elements with the switch hidden at the rear.

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Huge thanks to Dave The Trimmer and the team for doing such a fantastic job creating this bespoke product.

Castle Combe Track Day

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Another fantastic track day made even better by great TVR friends. I was in two minds whether to book this up as it is a bit of a trek for me but glad I made the effort. It was an early 04:30 start for me but the traffic was good and arrived at 08:00 for the briefing.

The briefing was interesting, I made particular note of Quary being the most crashed corner of any UK track so the advice given was brake before the hill, neutral throttle over the hill and then brake further once on the correct line on entry to the corner. I never quite mastered it but the car is still in once piece so that is a bonus.castle-combe-track-layout

I opted straight for the instruction which Peter managed to negotiate into the price of the day when he booked the group. The instructor was very helpful and showed me lines and gave me lots of useful tips.

Driving around the track you cannot help but notice the barriers are very close and no run off or gravel traps whatsoever. Clearly not a circuit where you can take the piss.

Peter also very kindly took me out in his car 5.5 litre Chimaera I must say I am very impressed with his new cam it ‘feels’ much faster that it did before, must be the extra torque.

Phil managed to capture some footage from the pit wall and kindly sent it to me.

The combination of instruction and going out with Peter by the afternoon I had a bit more confidence and was pushing the car harder I had a great run with the Porsche Cayman which pulled me through to my fastest time of the day 1:28.88.

The AD08R tyres continue to amaze me, manged to get up to 1.2G this time. Once you have heat in them they do not seem to let go.

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Bit of analysis from Harry’s Lap Timer:

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Great to see and catch up with Anthony Precat as well, we had a great run back and was enjoying watching the epic flames from his stunning Griff.

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Brake Upgrade

I have never been entirely satisified with the brakes on my Griffith, mine being the 500 has 260mm brakes which is in improvement over the earlier cars but they have always left me wanting more.

Upgrading the standard system
A couple of years after purchasing the Griff I decided to upgrade the front brakes. Speaking with my TVR specialist David Batty he recomended the following works

  • Renewing the front discs with standard items.
  • Replacing the brake hoses with braided hoses to increase the feel of the brake pedal.
  • Replacing the pads with upgraded Mintex  items.
  • Changing the standard brake fluid with DOT5.1 fluid.

The result of this works were brakes with certainly felt better and performed better. Perfectly adequate for fast road use.

A couple of years ago I started using my car on track. My first track day was at Snetterton. Aside from nervously drving around the track and trying to get out of people’s way the one thing a did notice as my confedence grew was the brakes were not fit for purpose. A couple of +100MPH braking at the end of the long straights and the brakes were cooked.

When you look at the standard TVR caliper it is easy to understand why the brakes do not work well on track.
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4pot brake upgrade
Looking at brake upgrades there are many options to choose from. Most owners who have upgraded brakes also have larger diameter aftermarket wheels which gives a wide range of options. I wanted to retain the standard TVR Estoril wheels which unfortunatley limits my options of what will fit under the standard 15″ wheel.

I also decided that I wanted an OEM quality product, I have been burnt many times before with substandard ‘upgraded’ parts from aftermarket companies. OEMs invest a lot of money in R&D and making sure thier products are up to scratch.

There are two companies who supply to OEM and provide a suitable upgrade to meet my requirements, AP and Alcon.

Option 1 was to upgrade to 16″ Estorils and fit the TVR branded AP 4pot CP6600 calipers and 300mm discs as fitted to the later Speed Six TVRs. Pictured below on Mark’s Griffith.
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Option was to go for the Alcon 4pot calipers with 295mm discs that fit under the standard 15″ Estoril wheels
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After speaking to a number of people about the options I decided to go for the Alcon setup from David Gerald. I did very much like the idea of retro fitting the TVR AP solution from the later cars, however the exspense of sourcing 2 x 16″ Estoril wheels for the front, new tyres and resetting the geo did not seem worth it for an extra 5mm of disc (295mm vs 300mm). What sold me on the Alcon kit aside from being able to keep my standard wheel was it is a direct bolt on kit so no adapters required for the caplipers. Interestly enough I found an owner who had what appears to be the same spec brakes (Alcon 295×28) factory fitted to his Griff in the development days. More info about the kit from David Gerald (now Classic World Racing) can be found below.

After having the new brakes fitted to my Griffth immediately noticed the increased feel of the brakes. The standard system always worked when I needed it but it never inspired any confedence. I am now finding I can approach corners and rounabouts much faster as I have confedence in the brakes.

I decided to book a track day at Bedford Autodrome to test the new brakes out properly. After warming up the car for a lap I started to increase speed down the straights and brake more agressively into the corners. Towards the end of the day I was hitting over 130MPH on the back straight and agressivly late braking into corners, I could not get the brakes to fade.

I am very impressed with the Alcon setup and I can honestly say it is one of the single best improvements I have made to the car.

David Gerald Alcon Griff Brake Upgrade

David Gerald Alcon Griff Brake Upgrade