Brake Mean Effective Pressure

[AMMO]

Interesting article that explains BMEP much better than I can here

 

The formula I use to work out BMEP is torque in ft lb x 2.475 / capacity of the engine in litres.

 

I have just worked out all the BMEP figures for all my engines that appear on the dyno-plot website here I have built many more Duratecs than that and should load more graphs but the ones that appear on the site will do for now.

 

Here are the figures for some of the more important engines:

210 2 litre 217.7 bhp / 164.2 ft lb / 203.4 psi BMEP

220 2 litre 226.7 bhp /171 ft lb / 212.5 psi BMEP

260 2 litre 263 bhp / 183.6 ft lb/ 227.4 psi BMEP

280 2 litre 286.5 bhp / 186.4 ft lb / 230.9 psi BMEP

300 2.3 litre 298 bhp / 219.5 ft.lb / 232.16 psi BMEP *

300 2.445 litre 307.5 bhp /224.8 / 227.55 psi BMEP

310 2.2 litre 312.6 bhp / 200.7 ft lb / 226.8 psi BMEP

 

* Dyno runs on this engine were not finished as it was late and I wanted to get home. It was a very well developed engine that was built after the 2445 cc engine. It is in fact a 2.340 cc with 89 mm bore and 94 mm stroke. By optimising the induction lengths and cam timing I am confident we would have seen at least another 5 to 10 bhp. It certainly had the torque to do it.

 

The reason I wanted to get it home was that I had a 2.2 litre crank, rods and pistons waiting to go in. The 2.3 engine was finished as far as I was concerned. I had lost interest in it to the point that I didn't want to waste another hour fiddling with it to find out what it made.

 

The 2.340cc engine had the crank, rods and pistons removed and became the 9,000 rpm 310 bhp 2.2. This was the first engine I felt was truly my own, made the way I wanted. The reason for de-stroking is so we could rev the engine further and make use of the breathing ability of the head. The fact that the same head made 312 bhp on a 2.2 would indicated from experience that it would have made around the same power and a 2.3 but with more torque and less revs. The fact that it has less torque is of no real relevance if the car is geared right. I would argue that less torque might actually be better in a light car. After all we aren't Americans who rely on big cubes. I like to think we Europeans do things with a bit more finesse. Why do F1 and MotoGP chase horsepower and rpm rather than torque?

 

Big capacity is OK in a rally car but in a Seven I personally like the idea of a 2 litre. The 2445 cc engine was comparable to something like a Millington Diamond 2.5 that is used in rallying. It even sounded a bit like this one

 

Back to BMEP. As you can see all the engines are in the region of 230 psi. According to the article linked above that is more or less the accepted maximum figure. The engine designer who is drawing my new 2 litre crank also agrees with the 230 psi figure and would be suspicious of anything much higher. Dave Walker who put the flea in my ear has also never seen a 2 litre with more than around 185 ft lb of torque. I am confident that once we have the new crank and a few other bits we will see the 2 litre engine come into its own finally when we get to rev it to 9,500 rpm.

 

In the BMEP article that is linked above they also mention F1 engines with 206 ft lb of torque and 220 psi BMEP and Nascar Cup engines with 226 psi BMEP.

 

Talking of Americans and big cubes, how about a 1,000 cubic inch /16.5 litre V8 with 2,150 bhp and 1,500 ft lb of torque. here

 

The BMEP for the big V8? 226 psi. This engine won't last long at 9,000 rpm and something like piston speeds of an astonishing 38 metres a second. How about 32mm cam lift? On the drag strip if it does a 7 second pass the engine will have rotated only around 8,000 times. I wonder how many passes you can make before you need a re-build?

 

Torque or no torque, I think I'll stick to the Duratec with total capacity of 2 litres instead of V8's with cylinders of over two litres.

 

Hope you found some of this interesting.

 

 

[oilyhands]

Torque/BMEP figures are the great bull**** buster, I have a spreadsheet here that calculates maximum BHP at any particular RPM for a particular capacity in 4 or 2 valve form.

 

If your see BHP claims that look hookey, do the torque calculations, generally engines make peak power at around 90 of peak torque, so by working back you can work out the torque at peak power and guesstimate it at peak torque, if this is more than 90lb/ft per litre on a 4 valve then be suspicious, more than 94 then be incredulous.

 

Oily

[myothercarsa2cv]

Thanks, Ammo, very interesting! Never heard of BMEP until you mentioned it a couple of threads ago.

 

So I just worked out the 2CV and it's 118 psi... 1.6 K standard apart from slightly modified TB is 148 psi. Pretty low! But judging from that article, you can be pretty proud of your engines' figures!

 

So working backwards... The max torque (assuming 230 psi is about as good as you're ever going to get) a 1.6 K could make is 146 lb ft and the 2CV 56 lb ft. That would be mental 😬 I'm beginning to like this calculation as it gives you a target to work towards

[Dr Slotter]

To add to this, BMEP is a good engine design parameter as it allows comparison of the ability of the engine to do work, as torque does, but irrespective of capacity. It's particularly good for comparing race engines, as at high speed WOT the value of BMEP gives a good indication of a particular design's ability to provide high airflow.

 

Technically, BMEP is the product (mathematically and qualitatively) of volumetric efficiency (how much air can you get in), AFR (how well are you using the air you've got to combust the fuel) and fuel conversion efficiency (how well are you using the energy in the fuel).

[Nov-07]

If BMEP is, as suggested in the article, a theoretical concept, how is it measured? Many years ago I flew from Southend (yes, really) to Kuala Lumpur in a DC6. We did stop on the way 😬 When visiting the flight deck I noted that the Engineer's panel had a "BMEP" gauge which was displaying readings from all four engines. What was it measuring and how?

 

[Dr Slotter]

It will have been the output of a dynamometer measuring the torque on the engine shaft.

[AMMO]

I did more BMEP calculations this morning.

 

For years I have been quoting figures for the Nissan touring car engine. This was the engine to beat. I have been saying that the power for this engine was 312-314 bhp with a rev limit of 8,500 rpm. I have also stated that after further development the engine allegedly made 324 bhp.

 

Some months ago I tried to call Graham Dale-Jones who was one of the people who developed this engine at IES, but he has sold the company and moved on. I sold a mate's Superflow 901 dyno to IES and did a little bit of development work there circa 1998. I know Graham a little bit and always used to pop in for a cuppa if I was passing but haven't done so for years. I'd sometimes sit in his office and have a natter. I also know the guys at AER who took over the development of the Nisan so they are next on my list of people to talk to.

 

Basically, to make 314 bhp at 8,500 you would have to have 193 ft lb of torque at the point of maximum horsepower. 238 psi BMEP. At the point of maximum torque the BMEP would be even higher. I tried to get some more figures for this engine. I was told a couple of days ago by someone I respect that in its final guise it had 200 / 205 ft lb of torque at 6,000 / 6,200 rpm and 331 bhp @ 8250. This would give 253 psi BMEP at the point of maximum torque. If you work out the torque figure at the point of maximum power you get 210 ft lb. The torque figure at max bhp is higher than the torque figure at max torque. That sounds very wrong to me. BMEP is now 260 psi. Can this be right with everyone else quoting 230 psi maximum?

 

Pulled this from a thread dated 2003 here

 

"Standard specification in the Touring Car format is a 2.0-liter, so the car has a modified version of the 1,998cc-inline four-cylinder setup that is subject to explicit specifications. One regulation states that teams cannot alter the position of the valve centers, limiting the size of the valves that can be used, however leaving the specific size and configuration of the valves up to the developer. In Audi’s case, this meant 4-valves per cylinder for a 16-valve setup.

 

With regulations in mind, every possible modification is made to the engine in an effort to optimize power and reliability as much as possible. In full race specification, the modified engine produced 296bhp at 8,250rpm and 188lb ft torque (225Nm) at 7,000rpm. For the 1997 season, power was bumped up to 305bhp at 8,250rpm and 217lb ft torque (260Nm)."

 

If you do the numbers for the 296 bhp engine with 188 ft lb at 7,000 rpm you get 233 psi BMEP at the point of maximum torque. To make 296 bhp at 8,250 rpm you still need 188 ft lb of torque at maximum rpm. This also sounds wrong to me. Torque should have fallen by the point of max power.

 

For the 305 bhp engine you get 268 psi BMEP with 217 ft lb of torque at the point of max torque. At a max power of 305 bhp @ 8,250 rpm you need 194 ft lb of torque = to 240 psi BMEP. The latter figure of 240 psi BMEP is more credible according to some but the 268 psi figure is in the realms of science fiction.

 

Do these Touring Car guys know something we don't, when everyone else accepts that 230 psi BMEP is around the maximum you can expect?

 

The Vauxhall detractors always said that the BTCC engines only made 280 bhp. I know an ex Swindon guy that confirmed this to me. I also heard of a VX engine that was being transported overnight that sort of ended up at a competitor's dyno and made 280 bhp. Could be an Essex tale with no truth in it, but still a story I like to tell.

 

I watched some old BTCC videos on YouTube. If the Nissan had that much more power than the VX why wasn't it much faster and piss off into the distance? One thing that strikes me about the bumper cars is that they all seem pretty even in speed. If there was 50bhp difference between the VX and the Nissan I would have thought that there would have been a larger difference in speed.

 

I hope I have done the maths right and that the figures are correct. If I have made a mistake I would be happy to be corrected. If these guys are truly getting 250 to almost 270 psi BMEP from their engines I would like to get some for my race engines too. Maybe I'll ask Santa to bring me some for Xmas when I should be starting to upgrade my puny 280 bhp 2 litre Duratecs. They really could do with some as they only have an average of 185 ft lb of torque and 228 psi BMEP.

 

Edited to correct spelling and sentences that made no sense at all!

 

 

Edited by - AMMO on 24 Feb 2013 10:14:58

[peterg]

Well known and sadly missed motoring writer LJK Setright used to quote BMEP in a lot of his articles and made a comment to the effect that for an NA engine BMEP is a measure of how clever you are, for forced induction it's a measure of how brave you are...

 

[Jason Plato]

the dodgy fuel in the roll cage raised power

[Klunk]

Ammo, this is probably complete cr@p and unrelated, but didn't normally aspirated BTCC cars make good use of Helmholtz resonance to force air in at high revs as I believe they all ran airboxes at the time? Presumably this increased the volumetric efficiency at high revs and would yield more power at points where you would expect it to drop off.

 

Giles

[elie boone]

Are the BHP figures with or without waterpump/alternator ? but this could only be 5 to 10bhp surely ?

[Birkin S3 ZA.]

Hi AMMO

When you get maximum torque on various engines at different rpm’s, how do you rate there efficiency? Some normal road engines will give max torque at about 3000 rpm and max hp at 6000 rpm.

Some Japanese motors will give max torque at 5500 rpm and max hp at 7000 rpm, when you look at some of the dyno charts of your motors the max torque is very close to max revs.

So when everything is the best it can be on your builds, the two figures would be very close together?

Closer the better, or when the efficiency and max torque is at near max rpm as you can get it.

Just so you could let us know how you see the connection with BMEP high in the rpm, to get more hp you have to keep looking for more revs.

When you get to 9500 rpm where would you expect max torque to be made?

 

[AMMO]

Giles

 

I have no practical experience of Helholtz resonators although I have mentioned them in the past. I have done work on airboxes on race motorcycles. On bikes you have little room but what seems to work is running a big airbox if you can, several times the capacity of the engine if possible, and making sure you have a cold air feed. I tested and appraised the airbox on the Rizla Suzuki that John Reynolds won the British Superbike championship on and a Ducati Supermono that won at Daytona. Both bikes had the air horns and throttle bodies modified by me. On the flowbench the airboxes offered little or no restriction. In the case of the Suzuki that used the bottom of the fuel tank as the top of the airbox we lost only 1 cfm when the long inlet ducts were fitted. Quite impressive I thought.

 

In the case of the Nissan I can't remember it having an airbox as such. I do remember that the head was reversed and that there was a box bolted onto the individual throttle bodies. It had a large front facing flat element K&N or similar filter that was exposed. Air pressure under race conditions never went up more than a few millibars. The velocity in the ports is much higher than the road speed. I think I calculated that you had to be doing 185 mph to match the airspeed in the intake ports of a well developed race engine.

 

I personally can't see vast increases in power from an airbox. Small increases perhaps but nothing in the region of 20 or 30 bhp. They also seem to smooth things out and the torque and power curves are less spiky. I really don't know enough on the subject but more to the point I haven't done enough testing to comment with convinction. I do know that you can easily lose power with a badly designed airbox. This I have seen.

 

With Caterhams the subject of airboxes comes up when there is a need to silence the intake noise. When we needed to silence a 307 bhp engine we fitted the biggest (and unfortunately ugliest) box we could find. It was actually one intended for a six cylinder engine as I thought the one available for the four cylinder engine was too small. It didn't help that we were running 8 injectors with some outside the trumpets so apart from being long it also stuck out a mile. The airbox was huge but it is what I reckoned it needed. The engine was heading towards 2.5 litres in capacity and ran 54 mm taper throttle bodies at the time. The later 54mm bodies outflow even the old ones we used. The engine used a lot of air. It is easy to lose 20 bhp with an airbox and having worked very hard to get 307 bhp I wasn't going to throw power away. Luckily we only lost 5 bhp so we could still call it a 300 bhp engine.

 

Elie

 

Honda motorcycles used to quote figures for their bike engines that didn't take into account the losses of the alternator and water pump apparently. I take parasytic losses quite seriously as running the alternator and water pump can lose you a few bhp. I have never tested how much power they use but I can't see it being that much. The extra power you get is the icing on the cake when you are looking for the last few bhp. I agree with you that it is probably only 5 or 10 bhp. Possibly less? That's a guess. Without doing the testing I wouldn't like to bet on it.

 

Birkin

 

Race engines tend to make their power higher up than road engines. The more airflow you have the more tendency there is to make torque and power higher up the rev range. On a road engine with restricted air flow, small valves, undersize ports, restrictive air cleaners you can see the power peak at lower rpm. Removing the restrictions and the power moves up the rev range. A simplistic explanation would be the difference between your Zetec and a Duratec. You could say that the Duratec is like a Zetec with bigger valves and ports. The restrictions have been removed. The result is that when the Zetec power peaks at around 7,500 rpm or there abouts the Duratec still isn't over and done with at 8,500 rpm. That is principally because of the additional airflow.

 

As for the upgrade to the 280 bhp engine, the torque will remain exactly the same unless we can screw the extra foot lb or two out of it (which is unlikely). The rpm will make the difference because we will be able to use the power that is already there at higher rpm but are afraid to use.

 

Remember that dynos do not measure power. They measure torque. The formula for power is torque in ft lbs x rpm / 5250. The more you can move the torque higher up and increase the revs the more power you will make. F1 engines make high power figures with little torque because they can rev to 18,000 rpm.

 

For example if we can make 280 bhp at 8,500 rpm with a 2 litre Duratec that means we have 172 ft lb of torque. 172 ft lb of torque at 18,000 rpm for an F1 engine is 589 bhp. If we can keep the torque from falling too far there are power advantages in being able rev the engine more. The graph clearly shows the power still rising at 8,500. here A slight over rev of 280 rpm gave another 6.5 bhp. If the torque doesn't plummet and we can rev the engine more we will see more power.

 

"when you look at some of the dyno charts of your motors the max torque is very close to max revs." That is the point. Power and torque should be further apart. When we eventually reach maximum power with more rpm the power and torque will be further apart.

 

How do you measure efficency? BMEP.

 

 

[AMMO]

Still trying to get to the bottom of the missing BMEP from my engines. I still don't believe the claims for the Audi engines who are quoting torque figures that are very hard to believe.

 

Is it that my text books and information are out of date and that 230psi BMEP and torque per litre figures should no longer be used? If so what are the higher figures? Is it really between 250 and 270 psi? I wish someone in the know would tell me.

 

If you really could get 108 ft lb of torque per litre N/A then why are people like Millington not getting 270 ft lb of torque out of a 2.5? Or anyone I know getting 250 ft lb out of a 2.3 litre Duratec. Most sensible people I know are quoting sensible figures for these engines.

 

I spoke to an engine designer that was involved with BTCC and asked him the question about the figures we see quoted. His reply was short and to the point. "They're lying".

 

Whether the lie is intentional or not is another matter. In my racing years I met a lot of people who believed their own BS with an almost religious fervor.

 

Dyno errors or a dynos that reads high could be a reason. Coast down on a rolling road or transmission absorption figures that are wrong. Incorrect corrections for atmospheric conditions perhaps? A combination of the two and power and torque figures will rise.

 

I had my Mini rolling road tested years ago by a very competent guy and successful racer. There is no doubt in my mind that his rolling road read high. I reckon my Mini made around 82 bhp. His rolling road said 104 bhp. His set up skills were second to none. Carburation and ignition were perfect. His rolling road figures? Hmmmm.

 

A 950cc Guzzi on a Sun Ram 12. We'd made an adapter to be able to run it on a car rolling road. Made a credible 85 bhp at the rear wheel. When the dyno operator told me that was 125 bhp at the crank I just laughed. Losing 40 bhp in the transmission is nonsense. I tended to work on around 7 bhp transmission loss on a motorcyle of that power. That would make the crank power 92 bhp. We had previously seen 91 bhp on a Shencke engine brake with a similar engine. So close enough.

 

If I was gullible and wanted to believe my own superior tuning skills I would have gone around quoting this silly 125 bhp figure. 40bhp is almost 30 KiloWatts. The power has to be lost somehow. It is lost in heat. Imagine sitting on a motorcycle that is giving off as much heat as 30 1,000 watt heaters from the transmission. Your arse would melt.

 

A motorcycle engine builder friend also says that he has to contend with competitors that make extravagant claims for their engines. Most motorcycle rolling roads measure rear wheel power. By then adding a percentage loss you can make up a crank power figure. He said that the percentage transmission losses people are quoting would make the chain glow red hot.

 

As I have mentioned before we have raced against people who used to quote higher figures than us but we used to go past them in a straight line. When we were winning races by 10 to 15 seconds the guys with more power were finishing tenth. They could talk the talk but not walk the walk. Rider ability was quoted as our advantage. I admit we had better riders, but in a straight line when you are neck and neck?

 

My conclusion is that we live in world of BS. If someone quotes a figure, another guy quotes another higher figure. There is an escalation of BS that bears no relation to reality. That seems to me what has happened in BTCC. As people are gullible they like to believe this stuff. The Max Power guys need something to talk about down the pub.

 

You can spend all your working life measuring airflow, dyno testing, measuring everything that can give you a small advantage. You do your best work and get a credible result. Then someone comes along with some graph paper and a crayon and draws a nice smooth line with more torque and power than you can ever possibly get that makes you look like a useless twat who will never be as good as those other guys.

 

So what happens to the guy that is honest and quotes honest figures? The only way you can show people is to get out on the track and kick everyone elses arse into next week. But even there people will find reasons why you are faster.

 

Whilst looking into these things I tried to call an aquaintance that has a lot of experience with engines. Ex Cosworth, Swindon and Mountune. A realist. He was the one that told me that VX BTCC engines made 280 bhp at 8,500 rpm. But to sell engines you have to quote higher. When comparing notes on Duratecs our findings and figures matched pretty closely. He had sensibly stopped building engines and was involved with new things. His wife answered the 'phone and I was totally shocked to hear that he had passed away six months earlier at only 50 years of age. I didn't ask how he died as it might have been seen as morbid curiosity. She did say it was very sudden. I did ask his wife how she was and if she was OK financially. I was relieved to hear that from a financial point of view she was OK. She sounded quite emotional on the 'phone. Understandably so. I told her that her husband was one of the good guys and that I admired his talents and his honesty. She seemed to appreciate that.

 

I found the news quite upsetting and spent the rest of the day thinking about the guy. All that work and knowledge is now gone. I also thought that some of the things I have been writing about and getting off my chest recently are not really that important in the great scheme of things.

 

Sorry to end on a bit of downer but it is good sometimes to have a reality check. As I have said before, racers (that includes engine tuners as far as I'm concerned) have a character flaw that wants them to show everyone that they are better than the next guy. Is it really that important?

 

Also sorry if all the posts sound a bit me me me. "I did this" and "I did that" seems to appear a bit too often even for my taste. All I can write about is what I have done and what I have witnessed.

 

I would like to thank the people who have emailed me personally who have read my scribblings and said that they have enjoyed reading what I have to say. Ex club members and non club members who can't post here. I appreciate it very much.

 

I think I have said enough for now. I got what I wanted to say off my chest. I hope you haven't found reading this too tedious.

 

AMMO

 

 

[McBreadhead]

AMMO,

Fascinating reading.

 

Sadly we live in a world of willy waving and, like a good lover is able to satisfy his woman no matter what his size, so good engines will outdrag a braggart's in a race. Comes down ultimately to results which do not lie.

 

Interestingly one engine builder I know says his engines in the field tend to outperform those with higher quoted power outputs, especially factory 'approved' units from Cosworth. And he will build for less money too.

 

Enjoy doing the important things in life

[myothercarsa2cv]

Not tedious at all Ammo! Always a good read. Whatever other people say, stick to what you do - if there was a way to get BMEP up to 250 or 270, I have no doubt you'd have found a way by now - and leave the BS to the others. What you have over most is that you can point people to power curves online for engines in your customers' cars, and people can see for themselves the difference between what you quote and what they get I doubt many claiming silly power publish their results! You don't often get that kind of honesty in any industry

[elie boone]

Losing someone you respect is always hard, makes you think about life.

Maybe Oval pistons and 8 valves can bring the BMEP up higher but is very complicated and probably need expencive materials.

I just wonder if any constructor ever tried oval valves ? to make the most use of the theoretical max inlet area. This will create most likely hot spots in the valve because it can't rotate resulting in a poor seal and the valve needs to have a bigger stem resulting in a lower gasflow due to a smaller intake area witch you can overcome with higher lift but as the valve will be heavyer it can limit your max revs, so by altering 1 thing you have a cascade of other problems to resolve

For me the ultimate 4 stroke piston engine is the 50cc twin from Honda at 320bhp/ltr

this is an engine from the 60's like the H 16 and DFV , in those days the engeneers must have been briliant ( like in the 30's with Auto union & Mercedes ) but also had the time and resources to try things, nowadays the first question before you even think to do a test for a product is what is going to cost this ? and will it work straight out of the box ?

I am by no means a engine builder, just have a curious and adventures mind

[peterg]

Quoting elie boone: 

Maybe Oval pistons and 8 valves can bring the BMEP up higher but is very complicated and probably need expencive materials.

I just wonder if any constructor ever tried oval valves ? to make the most use of the theoretical max inlet area.

 

Nearest to that would be the Honda NR but I would put money on the Honda engineers having tried oval valves at some point as well as pistons so the fact they haven't been used may indicate that it does improve the output...

 

The Honda NR (New Racing) was a V-four motorcycle engine series started by Honda in 1979 with the 500cc NR500 Grand Prix racer that used oval pistons. This was followed during the 1980s by a 750 endurance racer version known as the NR750. The oval piston concept allowed for eight valves per cylinder which generated more power due to the increased air/fuel mixture throughput and compression. In 1992 Honda produced around 300 street versions of a 750cc model, the NR (often mistakenly referred to as the NR750), with a 90-degree V angle. Whereas the NR500 had used an oval piston with straight sides, the road going NR750 used an elliptical piston with curved long sides. The bike became the most expensive production bike at the time when it was selling for $50,000

 

 

 

Edited by - peterg on 6 Mar 2013 08:32:14

[makingff]

AMMO

 

I must admit to understanding very little of what you write (my total lack of engine / engineering knowledge, not your writing) but that doesn't stop me reading and enjoying it. Who knows, maybe one day it will all make sense!

 

I do look forward to your postings and hope you continue to share your knowledge and experiences.

 

Simon

[Klunk]

Ammo,

 

Your story is almost an exact copy of my engine builder's. He works with autograss and Brisca racers. His speciality is mini engines and pintos but, like you, it doesn't really matter what engine you give him he will apply the same sound principles to it and produce a superb engine. Again, like you, he is conservative when quoting power which he knows won't sell him engines but he cannot bring himself to lie to customers.

 

He dynos all his engines on his own dyno and has told me of how other builders shock load the engines or put incorrect calibration weights on the dynos to artificially crank up the bhp. He has set up both my engines on the dyno and they have never needed rolling roading afterwards. This is because when he does it, he mimics how the load will be applied to the engine when it's in the car. It's this attention to detail which is seemingly missing with a lot of engine builders.

 

He's told me numerous stories of other builders changing rev limits/timing etc of clients' engines depending on who's spending the most money. This has even been done in between races at meets to ensure the underdog doesn't win.

 

I'm glad to say his determination to do the right thing is paying off. His engines are winning and they are reliable. Recently he had an autograss mini with 120bhp trounce a big budget Honda powered entry (not in a mini) with over 250bhp. The guy came across and couldn't believe it. The simple truth is though it wasnt the bhp that won it but how much of that power was converted to traction. He and the car's owner redesigned the rear suspension to do this.

 

As for your friend's comment "they're lying", he's probably right. Stick to your engineering principles/convictions and ignore the BS .

 

Regards,

 

Giles

 

 

Edited by - Klunk on 6 Mar 2013 20:52:14