With a few years of a 340bhp Westfield under my belt, I’ve found myself more and more hinting others against such levels of power. I did have the word “advising” rather than hinting in there, but that’s not fair as I don’t think a big power Westfield is a bad thing. Quite the opposite, in fact. It’s just a very different thing to when it was a middling power Westfield. Given that I’m strongly considering a rather dramatic change of direction for my car, I thought it best to write down my thoughts on what it’s meant, even if just for my own benefit. I’ll approach a few of the more popular themes when someone mentions a rather silly bhp for a Westfield
“It’s a handful on the road”
Well, I suppose if it’s a track only car, which mine has been for a couple of years, that doesn’t really matter. However, when it had an MOT, it was a fantastic road car. I never had to change gear to find a higher speed, just ride the massively flat torque curve. It’s a ridiculously docile car which, aside from a slightly grabby clutch (more OEM feeling ones that handle the power are available), could probably be driven by just about anyone. It’s about the furthest from a handful that you can get.
What you can’t do, however, is work it on the road. It is far too quick for us mere mortals to be aware of hazards, correct the car over any bumps, change gear, process what’s going on around you, have to change gear again and even by the time you’ve read this, you’re significantly above any speed limits or indeed speeds where you’d survive and accident. To that end, it does stop being a Westfield, and become the world’s smallest GT car. Great and smoothing out the corners and cruising up to the next one with the gentlest of squeezes of the throttle. Thoroughly dangerous when deploying all of the horses.
This is not a bad thing. In some ways it’s positive because you tend to drive slower and smoother, and you already know that you genuinely are the fastest thing on the road and have nothing to prove. The person with a 150bhp Westfield accelerating hard for 15 seconds between corners might be having more fun though.
“You can’t keep it cool”
More power, more heat. More revs, more heat. Can’t really escape that one. A Westfield also doesn’t have a lot of ways of getting rid of that heat. The bonnet opening is filled by a radiator originally specced to cool a 1.0 Polo. Now we’re trying to use the same area to cool a power output a comedy factor more than said Polo. This is where you spend your money.
The radtec radiator/intercooler combo was the single biggest investment in the turbo projects and it’s fulfilled its role beautifully. These are the coolant and intake temps recorded over a track session that must have had 26 minutes of full speed work.
That was on one of those rare summer days with actual sun as well, so mid 20s plus the sunshine baking the tarmac. Those peaks are within 1.5 degrees of each other – to handle that for all that length of time is particularly impressive. Though of course, I deserve more praise for staying out there that long.
I’d say one of the benefits of having a large amount of power is also that you can afford to lose some. My engine runs a tiny bit rich precisely to provide a little bit of cooling assistance.
“Turbo engines are laggy, peaky and difficult to drive”
You tend to see these comments from the older generation, and that’s fair enough… they’ve driven 80’s turbos and, frankly, they’ve earned that opinion! None of it holds true nowadays though. The very modern turbo engines are impressively responsive. I think the only criticism you can throw at them nowadays is they don’t tend to rev that high anymore.
My car sits in the middle of those two extremes. It’s not laggy, it’s not peaky and it’s easy to drive. It also revs to 7.4k and makes power all the way there. But it’s not as responsive as something like an EcoBoost when lower in the rev range. Fine on track, but I do think it would be a bit frustrating on the road. Then I suppose, we’ve already decided that the throttle is to be used sparingly on the road. Also, is it any worse than an N/A engine with cams aimed for top end power?
Back to throttle response on track, it’s fine. You don’t wait for the power to come in. You don’t wait for the boost to build. It’s all there if you ask for it. Take the following graph of throttle position (blue), boost (red) and RPM (beige?):
This shows the entry into a chicane, balancing the throttle through it and powering out of it. The throttle has been off for 4 seconds before this, suggesting I’ve caught a car up and it let me past on the exit. You can see the first input into the throttle produces an instant response from the turbo, and this is from 3.3k rpm so reasonably low for track work. This tracks the throttle position until the second application, where by the turbo responds again but is held back once it reaches the actuator level. Here, because the RPMs are in the mid range, the boost level is reduced to manage that massive lump of torque turbos like to give. Perhaps the reason they’re often described as peaky. The boost is now following a rising limit to keep the torque curve as flat as possible.
At the gear change, the throttle is off 100% for 0.5 seconds. The boost follows this, taking 0.6s to achieve 21psi again. Which yes, is higher than it was originally set but crucially, not higher than it has been mapped for. Either way, I think that’s plenty responsive enough.
So what do I think?
Big power doesn’t ruin a Westfield. I’m 100% confident in that. What it does do though, at least for mere mortals, is change it. I’ve found that corners on track are mere obstacles to be cleared ready for the next application of power. Get the car slowed down (no mean feat!), turn in, get it roughly near the apex, balance the throttle, wait for it to straighten out, then deploy the power down the straight ready for the next corner. It’s made me lazy in many respects. On a sequence of close together corners or chicanes, I won’t be taking stabs of throttle between them. Just a gentle squeeze to smoothly get me to the next one without arriving too quickly and giving myself too much to do. Quite the difference to when I had 150-160bhp on throttle bodies. I suppose in that respect it’s ironically safer on track as you don’t tend to go hunting for those extra tenths. You don’t need to. It’s probably quite telling that since fitting a turbo, I’ve never spun on track. I’ve gone straight on at corners more than once! But never spun it.
There is only ever one thing quicker than me on a track, and that’s a lighter, less powerful Westfield/Caterham. They’re usually on slicks, so a more serious effort than mine, but typically 100bhp or more down on me. And if they’re quick enough to catch me up despite the deficit on the straights, it shows how much I waste through the corners by not applying the throttle or pushing the car. Which isn’t speed I’m wasting, it’s fun and personal reward.
I’ve had a lot of fun with my Westfield, and I don’t regret any of the options and even at my most modest I think I’ve done a really good job of breaking the 300bhp barrier in the right way. Even if I never actually meant to. But I’ve had my fun now, and it’s time for a change. For a long time now I’ve wanted to build another, knowing what I’ve learned over the last 7 years. So I’m going to rebuild this one, with less power, and more revs, and less weight, and more noise.
Goodbye gentle beast. Hello bloody idiot.
That’s an RX-8 231 engine. It’s going to rev to 10k+, it’s going to breathe fire, it’s going to drink fuel like a water wheel and confine me to the noisy step on track days… and every now and again… it might even work!