A morning at Northampton Motorsport

[NigelO]

Ever since I bought my Zetec-powered Westie last year, the cold start has been iffy, the throttle response has been poor and the low-load fuelling has been wrong. None of it was awful, just enough to niggle - for example, the throttle couldn't be blipped quickly without causing spit-back through the throttle bodies.

 

So - after a bit of research on the forum, a trip to Northampton Motorsport was booked. Thankfully, Monday's wet weather cleared and I had a dry but somewhat chilly run down the M6 and M1 at silly o'clock on Tuesday morning.

 

First thoughts - very impressed with the setup - clean and impeccably organised, with some pretty serious machinery in the workshop - always a good sign.

 

Second thought - despite being a very busy man, Troy put up with me watching the entire mapping session and asking all sorts of daft questions - I really like to understand what is happening and he was happy to explain.

 

 

Super-clean dyno cell

 

 

 

Car being strapped down onto the rollers

 

 

 

Troy and assistant (sorry, I didn't get your name!) setting up the laptop to talk to the ECU

 

 

 

Some of the many ECU settings

 

 

 

Early tweaking of the low-rpm sites on the fuel map - the end result was significantly different to this

 

 

 

The Results

 

Now I'll be the first to admit that I was hoping for some extra power - the engine spec (2L Zetec silvertop with Piper 270 cams and Jenvey TBs) suggested there should have been another 10-20bhp available. The previous graph from the last mapping session in 2012 showed 172 bhp @ 6,500rpm and 147 lb ft at 5,500rpm.

 

The first power run gave about 170bhp, which was encouraging, if only to show that the original power figure was probably fairly accurate.  Troy also ran the car with and without the air filter, just to see if there was any restriction - the result was exactly the same, so it went back on.

 

However, despite a tweak to the cam timing and a thorough re-work of the ignition and fuel maps, Troy only managed to increase the power to 173.6bhp @ 6,500rpm and 155 lb-ft @ 5,000rpm, which he said he was surprised at - normally the cam timing tweak gives at least 10bhp. We worked out that something else was probably the limiting factor - we suspect its the exhaust manifold (OE Westfield)

 

Before and after graph

 

 

What the graph doesn't tell you is:

 

1) I can now blip the throttle without any hesitation

2) The pickup from a closed throttle is much improved

3) Throttle response is noticeably better

4) It's smoother throughout the rev range

5) Power delivery is less "spiky"

6) The pops and bangs on the over-run have almost disappeared

 

The combined result of all of the above (and the torque increase of 5-10 lb-ft from 2,750-5,000rpm) is that the car is quicker and easier to drive, but not because its more powerful.

 

So - a huge thanks to Troy and the team at NMS - a very worthwhile day out

 

I swore blind I wouldn't get onto the very slippery slope of chasing power, but I already find myself looking for a better exhaust manifold and some 285 cams....

[AdamR]

Don't sweat it about the manifold, I've seen close to 200bhp @ 8000 rpm from a 1.8 Zetec on the same dyno that NMS use. With the torque (and power) curves dropping off as they are in your case, I'd say maybe the head could do with a fettle if you want more power? As well as the cams, of course. You will end up with a less 'driveable' car though, the slippery slope...

 

The DTA EX48 ECU you have there is pretty old and not very advanced, so the 'throttle on' response is tricky to tune in - great to hear Troy has improved it significantly though!

 

As you said, no bigger headline figure but a quicker car due to much smoother map and better torque - I've always found the same from a proper map and glad to hear you have too

[Rob Hunter - Club Secretary]

Really interesting read, definitely something I'm going to have to do myself. 

I'm getting similar symptoms on my 2.0 blacktop, spitting back through the carbs and popping on overrun. Only had the car 3 weeks so all I've done is sort an earth leak and balance the carbs up (one was running very lean). 

Didn't realize the Westfield manifold was so restrictive as I'm looking to upgrade from the standard cams (not sure on Newman, Kent or Piper) but keeping the standard internals and Omex 200 to get to circa 180-185bhp if I can

[Julie Hall - WSCC AO Representative]

Northampton Motorsports, I can't sing their praises enough, they sorted my car out when I first purchased it and it still runs sweet now. I don't think that you will struggle to keep up in the Peak District though Nigel, my car makes everyone feel powerful in comparison.

 

power vs rpm.pdf

 

[thebutler]

I went from the Westfield exhaust to a custom made Simpson racing one. Difference was day and night. Apart from the power gains (also used NMS) the throttle response was greatly improved and engine just feels like it breathes better.

 

The quality of the welds on the Westfield manifold on mine (2000 Sport 1800) was shockingly poor, real booger welds that would have restricted flow

 

Pops and bangs on overrun is a sign of running lean. I had this too before I went to FI

[Steve Smith - Joint Hampshire & IOW AO]

Nice to read about your visit to NMS. My car has know done 200 miles since it’s IVA.

I would also like to get Zetec engine and suspension set up at NMS. Please can I ask what sort of cost was involved fo two parts of set up.

[NigelO]

1 hour ago, Steve Smith - AO Hampshire And Isle Of Wight said:

Nice to read about your visit to NMS. My car has know done 200 miles since it’s IVA.

I would also like to get Zetec engine and suspension set up at NMS. Please can I ask what sort of cost was involved fo two parts of set up.

 

You should call NMS - every car is different, so the costs for mine are unlikely to be the same for yours. However, I will say that I was very pleased with my bill!