Quiet Trackday exhausts:
I’ve been designing and building stainless steel performance exhaust for over thirty years. When I read Hangar 111’s claim that they had reduced the noise output of the supercharged 3.5Ltr V6 down to the low 90’s dbs - “with no power losses” - I was highly sceptical to say the least.
Greg Lock, Managing Director of Hangar 111 Ltd lists his occupation as an IT Manager on the Companies House website. Looking at his firm’s previous exhaust offerings (see other pages on this website) I can believe that! I recall he once bought an un-used 2bular domain name and set up a diversionary site to send 2bular enquiries to his own Hangar 111 website. A bit desperate I must say but that is his skill-set! Exhaust design? Maybe not.
They mention carrying out flow-bench testing against other after-market exhausts. Hangar 111 Ltd do not own a flow-bench – they do not manufacture any of the exhausts they sell. But I do know a UK exhaust manufacturer who claims to use a flow-bench for their R&D and I wouldn’t look to them for a performance exhaust of any description – ever.
The Hangar 111 QT V6 system –
is a baffled design – not straight-thru!
I have NEVER encountered, in 33 years of exhaust design/manufacturing, a baffled system that can out-perform a straight-thru exhaust. Hence my scepticism at Hangar 111’s “no power-losses” claim.
Looking at the gas-flow path, it enters the silencer and runs along Pipe A to the other end at 'X' - which is blanked off! The gas then has to fight its way out of Pipe 'A' through the holes and into 4 separate chambers - so far so restrictive. Sound waves are well chopped up and the gas has several paths to take before reaching chamber 'B'. The silencer exits to the tailpipes, at 'C' - can you spot them? - are well-hidden behind the inlet Pipe A - perfect for efficient gas-flow. Not! Their diameter is 44mm. For comparison, the 2bular tailpipes are 57mm diameter. Actually, there is no comparison - ALL 2bular exhausts are straight-thru designs - never restrictive baffled designs - like Hangar 111's Signature range.
Result? A power drop of over 20bhp on the Hangar 111 V6 QT system, a LOT of heat/back-pressure generated and reports of the silencer slipping off the factory link-pipe during track use because the inlet swage is too short and the slots cut into it also too short for the clamp supplied - an old-school 'U'-bolt type which needs a long slot to allow sufficient closing.
Incidentally, I did see a claim of “lightweight” in some of their marketing. This baffled QT V6 system weighs 17.6Kgs. The factory system weighs 16.4Kgs. The straight-thru 2bular QP V6 system weighs 9.8Kgs.
Back in January, I contacted the Advertising Standards Authority asking how I could challenge Hangar 111’s claims.
The ASA advised me to contact Mr Greg Lock, Managing Director of Hangar 111 Ltd to ask him for proof. I did this using registered post as per ASA guidelines. A period of 5 days was allowed for him to reply.
He didn’t reply.
For comparison, here is the factory exhaust internals -
When the exhaust valve is open - you can't get any more free-flowing than that. Just a pity it's the wrong bore.
The later factory exhausts (as above) fitted to the Evora 400 and the Exige 380 are notoriously LOUD. Once the exhaust valve is “open” the system is a straight-thru 3” (76mm). A very difficult exhaust diameter to keep under control - noise-wise - on a supercharged install. Great for marketing! A car that sounds like it looks is always a good thing for a salesman. Not so good for a UK trackday enthusiast though.
I carried out back-to-back dyno tests between the 76mm factory system fitted to an Evora 400 and my 70mm bore, straight-thru QP (Quiet Performance) V6 system. Here is the dyno graph –
The 2bular system shows a slight increase in power and torque. I was happy with that as the exhaust was significantly quieter than the factory system. 98dbs versus the factory 109dbs with no resonance silencer or tailpipe add-ons! It’s also a smaller bore - 70mm - factory system is 76mm but boost (and power) are increased with the smaller bore on this install. No ECU tuning was carried out. It would have been nice to have another dyno run a month later just to see how much the ECU adjusted for the greater boost but the car was sold along with the exhaust shortly after.
I was interested to see the new Lotus 'Trackday' exhaust appearing on some internet forums. A very expensive piece of kit! Over £2000!
See images below. A round silencer, 8" (200mm) diameter with a 3" (76mm) bore - (Uh-Oh)! A large resonance chamber at the entry end and a re-packable section. A bit like MY old 2ZZ Re-Pack designs except I used a 70mm bore for 400bhp. I've seen similar removable end-caps before on the Cheeseman exhausts for the Caterham cars. I know from past experience how difficult it is to control the noise on a 3" exhaust and with the boost drop on that diameter, it would have been better to use a 70mm bore. The dyno-graph above shows the benefits of that particular diameter.
Looking at the packing materials used on this expensive track exhaust, I reckon they will last a whole morning's worth of laps No wire-wrap around the perforated core-pipe to protect the long-strand glass from migrating through those perforations. This system has a fixed (welded!) internal perforated core-pipe so it can't be removed. That makes for an awkward re-packing task. Must admit when I removed the end-cap, the material was bulked up at one end. Rammed in with a broom-stick maybe? Two things you want from your exhaust packing. A uniform density around the core-pipe AND a reasonable certainty that the packing will STAY inside the box. Not with this baby.
Funnily enough after some great fan-fare on the forums, the above exhaust seems to have disappeared from view - and the Hofmanns website!
Take a look at the 2bular 8" Re-pack below. It's an off-set design - not a central in/out due to space restrictions on the 2ZZ. You can see the wire-wrap around the core pipe protecting the packing material from the gas-speed of the supercharger install.
The 2bular core-pipe is removable, so the re-packing was easy! Place the whole assembly on the work-bench and roll it up like a jam-roll. I use expensive Acoustafil packing and as time went on I realised that with all the experience I had gained over the years I really didn't need a Re-Pack exhaust! That wire-wrap is a very important feature too but you have to ........... ...... .... then you have to .... .. ....... .. . But it seems certain manufacturers still don't get it
Perfect. Acoustafil is expensive but it works. This Re-Pack was removed from a damaged system on a 2zz TVS1320 install - several thousand miles on a high-stress motor - no issues found with the packing.
If you've bought the Lotus Track exhaust you might want to think about the work needed on the core-pipe and better quality packing materials.
PS. DON'T CALL ME.
A word of warning to anyone who has fitted an expensive V6 titanium exhaust. With the engine flopping all over the place on trackdays and the exhaust being used as an engine steady-bar, be advised any hanger rods welded to the pipework can seriously damage your exhaust!
That's the stainless factory exhaust after a few trackdays. Repairing a broken Titanium exhaust is not easy and seldom lasts.