Firstly I'd like to thank again the VW Vs V8 shoot out drivers and teams for brining what was an awesome line up of vehicles to RACE SHACK for a shoot out on our second open day

BHP figures below are rear wheel – Torque figures are calculated engine torque using roller rpm, engine rpm and measured roller torque to calculate back for engine torque actual roller torque is available but most of us are used to seeing engine torque so I've used that number for these results.

Mustang dyno's measure rear wheel BHP in a slightly different way to other makes of chassis dynamometer - please see the article linked below in the tech section for more info - the method used has been shown to more closely reflect the actual power available at the wheels and tends to be lower than the numbers you will see from other makes of Chassis Dyno.

I've given rear wheel HP as we don't use any fudge factor to work out flywheel HP as the parasitic losses for every vehicle's drive train are different – as a very rough guide a T1 based VW gearbox and drive train soaks up 15–18% of available BHP – large 9” rear ends and power glide style boxes and those big tyres that the V8 cars below are using soak up anything from 15–24% of available power. Keep in mind that it's your tyres that transfer the power to the road that makes the car go – so it's the rear wheel HP performance that dictates the vehicles actual performance and so this is the number we focus on at RACE SHACK.

Heres how it broke down

Jim McGhee had brought his amazing corvette stingray with its blown 7600 cc big block chevy engine. Jim runs on street tyres and unleaded fuel and runs a FAST efi system which he was aware was running rich and not yet optimised also as we did the first warm up passes we could see that the intake to the supercharger does not get to full throttle travel – this is robbing Jim of lots of power – non the less with Jim running ordinary pump fuel that's right not race gas, not any additives, not even super unleaded he still made the following numbers.

330 rear wheel HP @ 5537 rpm with a peak engine torque of 328 ft / lbs @ 4419

That's 43 BHP per Lt of engine capacity.

The system was rich across the entire map which we know from experience could be robbing Jim of as much as 20% on peak power and once the intake gets full travel there will be big gains here too. Once the linkage allows full travel the AFR can be profiled again and the FAST system fuel and advance map altered to improve power and economy.

Jim also did a 13.7 second pass on the rollers from a standing start (no Trans break) with big (read huge) wheel spin on those huge street tyres. If you've never seen this car up close it really is amazing and very well put together – thanks to Jim again for bringing it down! – We hope to be helping Jim get the FAST system optimised and get his fuel bill a little lower in the near future.

Keith Ridley in his 5400cc big block engined escort has been on the RACE SHACK dyno before on our first open day and had retuned to finish what he started, Keith set up his car to be the first vehicle to do a trans break drag racing launch on a Mustang Dyno outside of the USA – this was a first at RACE SHACK too and we worked with Keith to make sure we were happy with the straps and chains required to hold down a big block chevy car on a trans break launch of this kind. The trans break (Transmission break) holds the car in a single position by balancing both forward and reverse gears simultaneously – the engine is wound up to a launch RPM in this case 4800 and when the lights go green the driver releases a button which disengages the reverse gear and the car is immediately shot forward as first gear drives the car off the line – it's a dramatic thing to watch at the track and the loads involved are huge hence the requirement for chains and straps.

After a couple of false starts we succeeded with an 11 second pass on the rollers with a trans break launch at 4800 RPM – and in the process captured some interesting torque data as he launched the car. This was a first and it fair to say there was some fine tuning of the set up and of Keith to get to a 10 second pass as he does at the track – Keith plans some more closed door testing at RACE SHACK before the new season to optimise his existing package

During the ¼ mile pass Keith registered the following power numbers

335 rear wheel BHP @ 5853 RPM with a peak engine torque of 291 ft/ lbs @ 5800 rpm

That's 62 BHP per Lt of engine capacity

Martin “Stretch” Charles in the VWDRC Pro #71 car with his 2165 cc Type one based motor with a side draft Webber on a T3 turbo was up next – Stretch and his crew were interested in what the engine AFR was doing under full boost so its fair to say that we were not pushing this package to its limits. While testing we found that the side draft Webber float bowl needle was not able to cope with the fuel demand with the engine under boost and by third gear the AFR had dropped to the point where performance was suffering however they were not so lean enough to endanger the engine itself – Stretch and crew tweaked up the overall fuel pressure in an effort to get more fuel in – this tends to be a balancing act as the stock style Webber needle valve on the float bowl can easily be overcome and flood the carb if pressure is pushed too high – the increase in fuel pressure did improve the AFR but ultimately the team need to source and fit either a glass needle valve which flows up to 30 % more than its stock predecessor or fit a direct feed to the float bowl via a boost controlled regulator to push fuel in quick enough to keep up with the on boost demand – lots more to come from this package watch out for it at the track !

During these fuel monitoring runs Stretch registered the following performance

164 rear wheel BHP @ 5212 rpm with a peak engine torque of 170 @ 4267

That's 75 BHP Per Lt of engine capacity

First and last up was Richie Webb in his street driven VW cabriolet – this street driven car has been entertaining the drag race crowds for that last couple of years with monster start line wheelies and quick passes - previously with a big nitrous system and this year with a very well put together custom built turbo system – the engine is a 2332 cc type 1 based motor with a host of custom built systems in place. Richie has been chasing an elusive 9 second pass which its fair to say is an awesome target for such a heavy street car. The intention for the shoot out had been to do a reference pass first thing in the morning and move on to a head change and then a direct comparison of CNC ported heads Vs hand ported heads – both of which were CB Competition eliminator castings – unfortunately problems with a slightly rich mixture igniting gas in the exhaust path as the car came up on boost and causing failure of the rocker shaft retaining nuts meant that Richie and Marco went straight into the head change – these guys worked without a break through until gone 6 PM when all but the die hards had gone home to get the car back on the dyno - now with the new heads with slightly smaller intake and exhaust ports to those that were removed.

The charge cooler was refilled with ice and the car lined up for its first run – in the cold evening air it made huge torque in second and before it even entered the third gear power pull test window the revs went sky high – the RACE SHACK crew and Marco the man behind the awesome turbo set up all called out together “Clutch“. After working all those hours to get it back together there was no way we were going to leave it there – we called it a night and retired for some well earned beers with a plan to reconvene the following morning.

Sunday morning dawned and with the help of a fry up to shake off the hangovers we made our way back to RACE SHACK – Marco and Richie made good use of the ramp to get the engine out again and get the stage one pressure plate swapped out for a Kennedy Stage two – the black magic disc was reused and looked remarkable good considering the load it had slipped at the day before.

Back on the rollers - but with no Ice for the charge cooler we started testing again – all this year Richie has been running mid to early 10 second passes with some top end traction problems as the car laid down its huge power and we were looking for clues as to where the team had been losing out in getting the power they needed to get the car into the 9's –

During the first run we observed that the waste gate would open as it should at the pre defined boost level to relieve pressure as the car came on boost in third gear – but the huge exhaust gas pressure on full boost meant that the gate would not close again and so would bleed boost until the throttle was lifted. The gate fitted is only rated to 350 BHP and could not cope with the huge exhaust pressure – the car was making big power and torque despite this massive loss of exhaust pressure. Marco and Richie made some changes to there progressive boost controller fitted to the car to try and improve the situation with the waist gate – this did help and the on the final run the gate held right up to the point where the left had drag tyre lost traction this was at 5762 RPM – just over 1000 RPM into where the cam in this engine package makes its best power – there was a full 1500 RPM of available power left which we could measure by using the Pull down system fitted to our Mustang Dyno but using the tie down would measure power that would not have been available at the wheels on the track as the artificial down force we could add could not be duplicated on the strip and so at that point we called it a day.

The tie down system pulls the car down onto the rollers and prevents tyres from breaking traction but this is in effect artificially adding down force – it's fair to say if you break traction on the rollers then you will break traction on the track. The roller knurling on our 50” rollers is designed to work with full racing slicks and the tie down system allows us to measure power past the point of normally available tyre grip up to a max of 1850 BHP rear wheel BHP.

Richie has already increased his available grip with a set of 8” slicks to replace the 6” ones which we tested with and he will be using this wider rubber next season – this will help with the amount of power they can transfer to the track and the team are already shopping for a waist gate which will take them to the 450 + HP zone which they need to do a nine second pass. – Also it should be noted that all the runs completed this weekend were done without the nitrous system – yep that's without nitrous!

Huge thanks to Richie and Marco for staying another day to take on the numbers set by the V8 competition ! – I look forward to seeing them in the nines next season.

During the test runs on Sunday Richie recorded the following numbers

315 rear wheel BHP @ 5762 rpm with a peak of engine torque of 296 fl/lbs @ 5434 rpm

That's 135 BHP Per Lt of engine capacity

Congratulations to Keith's winner of the V8 Vs VW rear wheel HP shoot out with his big block chevy making the following numbers

335 rear wheel BHP @ 5853 RPM with a peak engine torque of 291 ft/ lbs @ 5800 rpm

And congratulations to Richie on winning the V8's Vs VW BHP per Lt of engine capacity with 135 BHP per Lt.

I think with the 8” slicks Richie might have had it

There's always next year J

Conor