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2.0 Zetec Upgrade Info


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As this topic has come up quite a few times now, it probably has enough interest to become an FAQ.

 

However - what follows in this initial post is MY experience and results are based solely on MY set up. Also, when talking dyno figures you are often comparing apples to pears, as every dyno can and probably will give different numbers. In fact the same dyno and the same car can give different numbers on different days for a variety of reasons. So don't blame me if your car has different figures!

 

On to the FAQ's.

 

NOTE: When I talk numbers, I am talking "Flywheel or Crank BHP" - because that's what most of us use and compare down the pub. In fact, I always call it the "pub figure" for that reason. I will also refer to a "dyno" and that will usually be a rolling road dynamometer that reads power at the driven wheels, then uses a "correction factor" to convert this to flywheel/crank figures - again, it's what most of us have access to. I have no experience of the more accurate engine dyno's or hub dyno's so can't comment.

 

The figures I state are NOT absolute, they are just a rough idea of what you can expect based on what I have gleaned over the years and also my own personal figures that I have been given by the professional mappers.

 

How do we get Flywheel BHP?

 

Unless you take your engine out and connect it up directly to a dyno then you will be measuring the power at the wheels (WHP) and then using a "correction factor" to calculate the power at the crank. Obviously this is open to interpretation, but it is my understanding that is usually the result of a calculation by the dyno when the car comes off the throttle and it can gauge the transmission losses (please let me know if I have this right!)

 

Dynojet are one one of the biggest suppliers of dynos for measuring power at the wheels. I have read that certain patterns became apparent with the Dynojet dynos which led to the common 15% (2WD) and 25% (AWD) drivetrain loss rules.  These rules are usually applied to manual transmission vehicles as automatic transmissions are prone to more losses because of torque converters and more complex internal components.  The rules, however, are not absolute or 100% accurate. Transmission type, wheel and tire size, driveshaft weight, brake rotors, etc. all influence the drivetrain losses. It is best to understand that the common rules are purely for estimates and that the best use of dyno testing is to measure before and after results on a specific vehicle on the same dyno.

 

But we want some figures - so lets use my own results and assume we have a 181bhp result (measured directly at the wheels) and we measure a 29bhp drivetrain loss via the dyno at max power, so 181whp + 29 loss = 210bhp crank power which works out as a 14% loss in my case, close to the "usual" Dynojet figure mentioned above.

 

This "correction factor" will vary and so you can’t just use these figures on any old number. I have seen dyno plots where the drivetrain loss was shown as around 40-50bhp on a car with 135bhp at the wheels. So each car can and will be different.

 

NOTE: the calculations used will not not the same for all cars, all dynos, all operators - this is a sweeping generalisation to help give us all some idea of what to expect when on the quest for more power.

 

How much BHP at the crank does a 2.0 Zetec make?

 

Taking into account the above caveats and generalisations, here's some approximate CRANK figures:

 

  • Single throttle body fuel injection - 150
  • Twin Webbers - 150-160
  • Individual Throttle Bodies (ITBs) - 168-183 (my personal Silvertop, then my personal Blacktop figures)
  • ITBs and cams - 190-210 (most report at least 190, mine made 209.78 with Dunnell ZRV)
  • ITBs, hotter cams, better exhaust, ported head - 200-220 (research figures)
  • ITBs, even hotter cams, springs, better exhaust, ported head, pocketed pistons - 228-240 (according to Dunnell Engines)
  • ITBs, race cams, larger valves, springs, bigger followers, better exhaust, ported head, uprated pistons and forged rods - 250-255

 

Note: Forced induction (turbo or supercharger) can give you 230-400bhp but big numbers need lots of expensive internal upgrades and very good cooling systems. 


How do you get more power?

 

In very simplistic terms, to get more more power you need to get more fuel & air into (and then out of) the combustion chamber. Each of the above stages pretty much does this by increasing air flow in and out, plus allowing more air fuel to be mixed inside the combustion chamber by the use of more valve lift and longer cam duration. You will usually increase the compression as the numbers go up too. 

 

But just like baking a cake, simply throwing in more ingredients into a bigger mixing bowl might not actually give you a bigger cake once it’s cooked - and it could easily ruin a perfectly tasty recipe and turn it into a stodgy mess!

 

This is perhaps why some setups will see bigger improvements than others. Just adding a better flowing exhaust could potentially reduce power if the other parts of the system can’t match it. Likewise a ported head might not give the reported increase in flow unless it’s complemented by the other components. 
 

So bear in mind that as you upgrade one component, you could find another is a limiting factor that will prevent you getting the most (if anything) out of it.

 

I had more than a few discussions with Paul Dunnell before choosing the cams I used. When talking about the cams I eventually bought he said that they would give me a healthy increase in both torque and power right across the rev range from around 2.5/3k up without any other mods. He was right.
 

I questioned the need for head porting and he said that if I was looking at removing the head, then I should get the next set of cams up in the range and pocket the pistons, plus fit a better flowing exhaust. Oh and those bike throttle bodies won’t really work so well.
 

So I just bought cams and vernier pulleys - seemed sensible. 
 

The point of this is that my “recipe” of 42mm gsxr throttle bodies, Dunnell ZRV cams and the standard Westfield exhaust makes a well balanced and very tasty cake. If I try and bake a bigger one, I’ll probably need to change all of the ingredients or try a new recipe altogether. 

 

How do I get 200bhp?


The base requirement here is ITBs plus longer duration and higher lift cams or forced induction (FI). I think FI is a whole other ball game, so here we are talking naturally aspirated or n/a tuning. Your set up may also need the head ported and a better flowing exhaust to see “200” on the dyno you go to - but as stated, I’m using my experience as an example and thus publishing my results. 
 

I have just fitted a pair of Dunnell ZRV cams (and vernier pulleys) - no other mods to my existing setup of GSXR ITBs and std Westfield Exhaust (although I did need to increase fuel pressure as the injectors were on the limit).

 

So no head work, engine is a totally standard 2.0 crate Blacktop installed in 2016 (ran in hard and fast of course - no messing about 😁)

 

All I had to do was swap the cams, reshim it to suit the Dunnell specification (closer tolerances than Ford) and time the cams in using Vernier pulleys and a dial Gauge. The shimming was the difficult bit, but only because they are so hard to find! The process itself is just a case of measure clearances, fit cams, measure again, remove cams, swap around or install new shims where needed, refit cams and check again.

 

On to the results:

 

NOTE - this graph is power at the WHEELS  divide by 0.86 to get the Pub Talk corrected figure that was calculated on the dyno at the time.

 

Chris King Westfield Dyno.png

 

Here's the corrected FlyWheel power version - photo taken directly from the computer attached at the time - I'll round it off and call it 210bhp 😁

 

IMG_2042.jpg

 

And a direct comparison with my previous set-up (NOTE: different dyno operator for that one, NOT Daytuner - overlaid by me in PhotoShop). My previous setup was dyno'd at 183 bhp and 175 ftlb (corrected flywheel figures) but tailed off after 5500 revs.

 

Screenshot 2021-03-20 at 13.49.38.png

This is the bit that REALLY matters - just ignore the numbers as they are meaningless "mine's bigger than yours" pub talk - but the obvious increase in both power and torque right across the rev range from 3k up, is just lovely. Plus the flatter torque curve makes this a lovely drivable engine on road and track. 

 

Mythbusting

 

"you can't get more than 185bhp with the standard Westfield exhaust" - well, I'm sorry, but unless you mean 185 at the wheels, then you certainly can. I very nearly changed the exhaust because I firmly believed my previous dyno plot "proved" the exhaust didn't flow well above 5500 revs - I was wrong!

 

"you need 45mm throttle bodies for more than 180bhp" - mine are 42mm off a 1000cc motorbike, so wrong again.

 

no point in just putting cams in without porting and polishing the head” - I believe my “before & after” graph shows that cams alone CAN give a significant improvement. If the engine is apart, it would obviously make more sense to port the head, but I saved a considerable amount of time and expense whilst still achieving a seriously good result - and the car drives so much better with the new cams and map which is the main thing.

 

I am very happy to be corrected on any of the above - and as stated, the figures are for comparison, not absolute and are based purely on my own personal experience using my own engine figures given to me by respected professionals.

 

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I would say your transmission has lost 30 bhp not a percentage it would have been 30bhp if it was 100bhp or 500bhp at the wheels .

500bhp at the wheels would mean it's lost 80bhp through the transmission if useing a percentage .

Tony 

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9 minutes ago, wizzer said:

I would say your transmission has lost 30 bhp not a percentage it would have been 30bhp if it was 100bhp or 500bhp at the wheels .

500bhp at the wheels would mean it's lost 80bhp through the transmission. 

Tony 

Good call - I’ll amend the info 👍

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This is going to add petrol to my already simmering upgrade fire.  I have bog standard Westfield crate 2.0 L Zetec, so if I go the Westfield OMEX ITB kit are you saying I should be be disappointed  if I don't achieve the 150 to 170 BHP uplift.   With respect to cams, is it worth doing it at the same time as the ITB or better to get it all settled down then add the cams for another 20 BHP uplift.

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1 minute ago, Two7 said:

should be be disappointed  if I don't achieve the 150 to 170 BHP uplift.   

I’d say so. It’s pretty generally agreed that ITBs alone will give you 175 ish. 

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29 minutes ago, Two7 said:

With respect to cams, is it worth doing it at the same time as the ITB

You need a mapping session for ITBs to get the best out of them - so if you plan to add cams, it’s as good a time as any!

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This is great to hear Chris, thanks for putting it all on one page, certainly makes interesting reading and no mention of the classic Stage 1/2 from hot hatch guys or FORGED from the racers...

 

I have a 1.8 zetec that has produced 172/168 pub talk BHP (on last two different dyno's) on 45mm Jenvey ITBs and std injectors/cams and exhaust, which is more powerful than I am skillful....

 

However, I also have a std 2.0 blacktop that I am 'refurb'ing' and was wondering if it was worth the swap and upgrade cams....

 

or do I get head, cam, injectors and exhaust upgraded on the 1.8...

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1 hour ago, Chris Broster - Bristol & Bath AO said:

wondering if it was worth the swap and upgrade cams....

 

or do I get head, cam, injectors and exhaust upgraded on the 1.8...

I think it depends on what you want to use the car for. 
 

Not driven the 1.8 but my understanding is that it is a more free revving engine and probably a touch lighter. So it’s maybe a little “livelier” than the 2.0. 
 

But one big factor is if you fancy doing any sprints. The 1.8 is in a different class and there’s not a lot of competition that trumps a decently tuned Zetec. But move up to 2.0 and you are firmly into Redtop and Duratec territory where the Zetec will get it’s bum wiped. 
 

But for a road and occasional track car (and I expect to be challenged here!) the 2.0 will trounce the 1.8 due to its torque and drivability - especially if you get the sort of results I did just by adding cams!

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Gent's, just keep in mind how the FAQ section works; it might be better to move this out of the FAQ (even if only temporarily), if it going to be as wide ranging as it  starting to get, otherwise, there's going to be a few posts to delete?

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1 hour ago, Dave Eastwood (Gadgetman) - Club Secretary said:

Gent's, just keep in mind how the FAQ section works; it might be better to move this out of the FAQ (even if only temporarily), if it going to be as wide ranging as it  starting to get, otherwise, there's going to be a few posts to delete?

Feel free to move if you feel it’s warranted Dave 👍

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Would be nice if people could post their upgrades on and costs maybe.

Or even factual info on cams, CR or cylinder head work valve sizes e.t.c.

Keeping it as short as possible.

Then others hoping to tune theirs will possibly get answers.

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  • 5 months later...

Been InTouch with a pro head modifier today.

Modified head or Modified head + big inlets or Modified head + big inlets & exhausts.

See where it takes us!

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