What engine should I go for? - help

What engine should I go for? - help

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AinsleyB

Original Poster:

244 posts

80 months

Wednesday 18th January 2023
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I'm looking to build a 7 and I'm not sure what engine to start with.

Many years ago I built and raced one, back in the late 80's. That car had 185 bhp and was great, but I was an inexperienced 20 year old. Also back then the roads were empty and they hadn't invented speeding cameras. At that age I had pretty much no driving experience.

Since then I've ridden and raced motorcycles, on and off road. So I know all about power to weigh ratios and having more power than you can put down on the road.
I've a few motorbikes and just use them for weekend blatts on country roads - which is not different to what I want to do with the 7.
I own a 911, so have some power and luxury, which is great for touring abroad.

But I'm really not sure what to build. Would I find the 360 less exciting than my 1000cc KTM for messing about on ? Do I need to be looking at the 620 to get the same kind of rush.

When I'm on the motorcycle its all about squeezing out the power to match the grip, no traction control and pretty extreme consequences if you are a bit ham fisted. In the 911 the traction control stops it getting too hairy, plus the price of sorting it out if I bin it. What is it like in a 420 or 620 ? Can you put the power down on the road, or are you feathering it the whole time.

I intend to use it 99% on the road, so don't want to find I've wasted most of my money on something that's so quick its wasted on the road, but on the other hand I don't want to find its a bit of a let down compared to a sunny Sunday spin on one of my motorcycles. I don't want to end up paying for more power after getting used to it.

Anyone have any similar experiences they can help me with ?

Mr MXT

7,691 posts

282 months

Wednesday 18th January 2023
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Not Caterham directly, but I took my Duratec Westfield through various iterations from 180 to 250 bhp. The sweet spot for me was 210, equivalent to the Caterham 420. 250 was too much for the potholed, hedgerowed and cambered roads around here.

AinsleyB

Original Poster:

244 posts

80 months

Wednesday 18th January 2023
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So were you just spinning away the extra power then ? Or bouncing down the road ?

One of the things that makes the 911 quick is top notch suspension. On my motorbikes the suspension is endlessly adjustable, so you can waste hours twiddling it. In the end though, its easier to cope with more power on 4 wheels than on 2.

Mr MXT

7,691 posts

282 months

Wednesday 18th January 2023
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AinsleyB said:
So were you just spinning away the extra power then ? Or bouncing down the road ?

One of the things that makes the 911 quick is top notch suspension. On my motorbikes the suspension is endlessly adjustable, so you can waste hours twiddling it. In the end though, its easier to cope with more power on 4 wheels than on 2.
I was quickly travelling way too fast for the conditions and my appetite for risk. It became "track only" toward the end of its tenure.

nunuk

56 posts

66 months

Wednesday 18th January 2023
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AinsleyB said:
...
But I'm really not sure what to build. Would I find the 360 less exciting than my 1000cc KTM for messing about on ? Do I need to be looking at the 620 to get the same kind of rush.
...
Perhaps something in between? i've got 240bhp and it's too much for the roads i like, but on track i love to have them all on board.

Tiddy7

16 posts

17 months

Wednesday 18th January 2023
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Anything above 200 ish BHP is a waste of time on the roads, even with 8" rear tyres its just pointless, on the track then thats a different story especially if you buy your self some cheap slicks.

The novelty of doing 0-60s and scaring your friends soon wears off

Hard-Drive

4,076 posts

228 months

Wednesday 18th January 2023
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I have an Superlight R400K, which is very similar performance to a 420, although the K power delivery means the real shove comes in at high revs so keeping it properly on the boil on the road is unlikely. The 420 has more torque and a less peaky power delivery. The K is still plenty pokey enough to drive round at decent speeds without thrashing it though.

TBH if you are just concerned about whether a 420 is fast enough, and if it will feel as exciting as a bike, you're kinda missing the point. It's much more about feel, feedback, balance, handling, an utterly analogue unassisted experience and above all light weight.

My old car was only 125bhp but in some ways more fun on the road as you could work it hard and be going at half sensible speeds, and come back from a blat having given it full beans a fair bit. The really fast stuff is eye-openingly fast when you do open it right up, but the opportunities to do so on the road for more than a few seconds are far less.

Remember they all go round corners at pretty much the same speed, and although they are small and fast you can't overtake stuff like a bike can. Whenever I've been out on group drives, whether you're in a 620 or a 170, speeds are similar and everyone arrives at the same time.

In short, drive some and find out.

MK3 Dan

253 posts

144 months

Wednesday 18th January 2023
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Would something custom and bike engine'd be a possibility?

Still gives you the enjoyment of the high RPM and having to work the engine for maximum power delivery.

You also have reduced torque which could be a positive or negative depending on how you tend to drive.

AinsleyB

Original Poster:

244 posts

80 months

Thursday 19th January 2023
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The bike I like riding the most is a big V-twin. All the torque is very low down, so you sort of surf a wave of it at low revs. It redlines at 12k, but you ride it at 3-4k. So for me, I would probably enjoy an engine that doesn't need thrashing.

Hard-Drive, you make some interesting points - your right, the feel / feedback and balance are key. Also a valid point about them all going round corners at the same speed.

So perhaps the 420 is the right one for 99% road use. But then I never use the 911 or any of my bikes to their full potential and that doesn't stop me enjoying them, so why not get the 620 before they are outlawed ? Bugger, too much choice just prevents decision making.

I need to drive one, that will help settle the matter.

  • goes off to Google Caterham car hire*

DCL

1,215 posts

178 months

Thursday 19th January 2023
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Horses for courses - the power level you'd be happy with is very much down to your own personal experience and degree of adrenaline rush you are wanting to experience.

Certainly the chassis of the Caterham has a sweet spot around the 200 BHP mark for the average driver. More than that requires a little respect, and over 250bhp requires skills, and reactions, that are only gained with a few hours of Caterham driving behind you. Going to 300bhp+ and there's no reserve in the chassis - that's not to say it is uncontrollable, just that it needs a good knowledge of Caterham driving techniques such as subconsciously trail braking (and occasionally left foot braking) to keep it all in balance etc etc - basically all a bit scary to do safely do on public roads (at least for other road users who may witness you in various angles of yaw) .

I'm currently running about 320 BHP but have decide to 'down grade' to a more enjoyable 200-220 bhp to reduce the degree of concentration needed to keep things safe on public roads.


Edited by DCL on Thursday 19th January 10:33

AinsleyB

Original Poster:

244 posts

80 months

Thursday 19th January 2023
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OK, seems like 200 ish is the way to go. Despite my daydreams - I'm probably rubbish at driving smile

number2

4,268 posts

186 months

Thursday 19th January 2023
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Yeah, it's easy to get carried away when it's a 'paper' exercise!

Matt W

153 posts

237 months

Friday 20th January 2023
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The 620 is factory built only I believe, so the fastest home build 7 you can get is a 420.

ghibbett

1,900 posts

184 months

Friday 20th January 2023
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If you're looking to get a Caterham to enjoy straight line acceleration, then you're better off sticking with a bike.

My next door neighbour is big into his sports bikes. I took him out in my 220bhp full-aero S3 Seven and, whereas most people crap themselves when you give it everything, he wasn't at all phased.

However he was utterly gobsmacked at the braking and cornering performance.

That's where a Seven shines.

mickrick

3,700 posts

172 months

Saturday 28th January 2023
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ghibbett said:
If you're looking to get a Caterham to enjoy straight line acceleration, then you're better off sticking with a bike.

My next door neighbour is big into his sports bikes. I took him out in my 220bhp full-aero S3 Seven and, whereas most people crap themselves when you give it everything, he wasn't at all phased.

However he was utterly gobsmacked at the braking and cornering performance.

That's where a Seven shines.
^^
This. I have bikes in my shed. Following a very fast rider on sports bike, in the twisties will slow a Caterham down, whereas a bike in a straight line will leave one for dead. Several years ago, when I owned an R300, the R400 was considered the perfectly balanced Seven, ahead of the R500.
So around 220 IMO is the best balance for the road.

k20erham

372 posts

125 months

Sunday 12th March 2023
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Hi there,
Power (and torque) is nothing without control!!!!
A little like yourself I have owned and raced bikes and cars all my life (I'm 64) Although my garage list is not up to date I currently have and use when time weather permits:-
Yamaha R1 (05) full engine build to 210HP @ the wheel.
MV Brutale (14) Tuned to 160HP @ the wheel.
Lotus Exige (05) compound supercharged to 280HP @ the wheel
SL65 (06) Tuned in 2022 to very big numbers!
Caterham (98) Most may know this car that was originally Built by Courtney Autosport (Mint Green) just short of £100K in 1998.
Richard Breland started it's conversion from what was a Turbo Vauxhall red top with BMW box to K20 Honda, I bought it from Richard as an unfinished project, had great fun building and using an absolutely wonderful engine from parts I amassed from Neil Brown racing whilst looking after two Honda touring cars. I personally think that there is yet to be a 4 pot engine that can equal the K20 and K24 Honda, again in my opinion a Duratec sounds not as nice, and to me the sound is very important, if fact an essential element to the whole driving experience, it is not big numbers seldom can you use them anyway, hands up those that have been embarrassed by something/one half the power twice the skill? I have lots!!
All of the above require huge amounts of respect and talent when pushing on no matter where you drive them, I had the pleasure of working for Mclaren Automotive for 10 years and met and learnt a colossal amount from some of their Pro drivers. None of the above list have poor numbers as standard, and yes few could exploit their performance fully anywhere either, but I guess it must be in our blood to want more, seldom do we need more.

Sidecar Man

581 posts

60 months

Tuesday 14th March 2023
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k20erham said:
Hi there,
Power (and torque) is nothing without control!!!!
A little like yourself I have owned and raced bikes and cars all my life (I'm 64) Although my garage list is not up to date I currently have and use when time weather permits:-
Yamaha R1 (05) full engine build to 210HP @ the wheel.
.
Be interested to know whats been done to a 5vy Engine to get 210hp at the back wheel???

Digger90

19 posts

148 months

Thursday 16th March 2023
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With your background - and intended use - what you need is a Caterham Hayabusa! :-)

220bhp @ crank, 183rwhp, 469kgs. Outperforms a 420 Cup yet extremely tractable and forgiving as a road car.

As others have said, the feedback, balance, handling, agility, turn-in etc of an extremely light car - as well as the noise - are breathtaking. My car is 140kgs lighter than a 620R.... Yes 140kgs!!! Think about that for a minute...





Edited by Digger90 on Thursday 16th March 19:33

harryblue

5 posts

181 months

Saturday 18th March 2023
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I come from a bikes background, a bit of racing too, and in my opinion the 210bhp 420S/R is perfect for the road, you'll rarely use all it has to offer but you can give it full power in places and it's not too much. It's not going to be as fast as a 1000cc superbike, but you have to treat it with a bit of respect and it's blisteringly fast for a car, but you can also cruise sensibly in it because of the amount of torque on offer.
I found I had to rag the 310R to get a thrill out of it, the 620 was just crazy and a bit too much, but the 420R seems to be just enough to put a massive grin on your face with the power but not be too much, or too less.

Blue 7

153 posts

172 months

Saturday 18th March 2023
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I had a 120bhp live axle Caterham for seventeen years & although personally I didn’t consider that a slow car as such, I fancied a change & I’d always felt intrigued by the more powerful Sevens.

Mindful of the often repeated assertion on here & Blatchat that 200bhp is too much for the road, rather than jumping in & selling my car, I cautiously hired a CSR200 for a weekend… & absolutely loved it!

I part exchanged my live axle car for a 420R at Caterham Gatwick in 2019 & I haven’t looked back. I agree with harryblue’s comments that it seems like a good balance for the road. You can burble along on the torque quite happily, but when you do rev it out it’s thrillingly fast, for me, just the right side of frightening!

Like the OP, I did wonder if a 200bhp Seven would have traction issues & if perhaps that was what people were referring to when they said 200bhp was ‘too much for the road’. But I find, it’s remarkably good in that respect. Obviously, you need to be careful in damp conditions, but on warm, dry tarmac I find you can pin the throttle & get the change up lights winking, even in second gear without worrying about wheel spin.