Radical decision - SR3 or SR1 or SR4

[kartaphilos]

Hi,

I'm looking to purchase a Radical to do some club level racing & sprints/hills. I like the idea of aving two seats for instruction on track/tuning days and the greater protection I assume there is over a single seater. I was looking at a 1st gen SR3 but after visiting the Radical factory last week the SR1/4 are of interest. I've got a couple of questions that may help me decide....

- What is he weight of an SR3 compared to an SR4, I can't find consistent data on this. The SR3 seems to be 495kg minimum (dry?) and the SR4 465kg. Lighter the better for the hills.

- Would an 1300 SR3 be competitive in the prosport class of the Radical clubman challenge? How about the 750MC bike sports?

- Tyres. Are hillclimb compounds available for the SR3 & SR4 tyre sizes?

- What should I budget for a seasons racing?

- What's the typical cost for an engine rebuild?

Apologies for spewing out alist of questions on my first post, trying to get my head around my options.

Cheers,
Matt

[andylaurence]

I went with a two-seater for the same reasons. Number of people who've sat in the passenger seat in the 3 years of ownership? One. As far as protection goes, for the same outlay, you'll get a carbon-tubbed single seater and I'd wager that's safer.

As far as weight goes, 465kg is heavy. I'm at 421kg, but then I don't have a Radical. The fastest Sports Libre cars are under 400kg. I normally find I am on a par with the 1500cc Radicals, despite my 999cc, most likely because of the weight.

Avon and Yokohama do tyres for hillclimbs/sprints that will fit a Radical. I run 210/550-13 Avons at the moment, but I've previously run Yokohamas, which are much cheaper and slightly better for sprints as the Avons can be a bit soft for a long sprint. A new set of Avons costs exactly a grand by the time I've had them fitted/balanced.

I've stuck with a standard engine to avoid rebuild costs. If it goes pop, I can buy another and drop it in without much expense.

[kartaphilos]

Hi Andy,

I don't see many ADR's on the market, that would be another option. I've got the feeling no matter what I get, to make it competitive for hills would mean enough mods to make it not usable for circuit racing? Thoughts?

Cheers,
Matt

[LCM]

kartaphilos said:

Hi Andy,

I don't see many ADR's on the market, that would be another option. I've got the feeling no matter what I get, to make it competitive for hills would mean enough mods to make it not usable for circuit racing? Thoughts?

Cheers,
Matt

True!

For hills and sprints (BSC excepted) we tend to use relatively soft rear springs (for traction) and control roll by way a high level of front roll stiffness (and a torsionally stiff chassis). Plus, you want to carry as little fuel as you can without risking fuel surge by only part-filling a big tank - my Prosport ran a 8L bag tank and my Force runs with a 4L tank.

If you actually want to be reasonably competitive on the hills (ie not embarrassed) then you need to dismiss all thoughts of an SR3. It's big it's heavy, tyre availability is limited and it won't get to go fast enough to benefit from its high speed aero (I don't know where you got those weights from, but a couple of years ago we had an open kimono session on here re real world weights and IIRC SR3s were about 100kg heavier. You may still be able to search for it or Trev may remember and post a link).

So, you want a small, stiff, nimble car with a torquey engine, big brakes, good tyre availability and decent low speed downforce. These requirements lead you to PR6, Prosport/Clubsport, SR4 (SR1 if you want to buy a new car). Your ideal car would be a PR6 or Prosport with lightweight body, LCM aero pack, Hi-Spec or Radical BIG brakes [PF01 pads], a small bag tank, AIM logging, and one of PowerTed's Big 'Busas (1585, 1598, 1615) with a billet clutch and HD output shaft. For the money, Radicals to this spec do remarkably well on the hills. They aren't as fast as a Force (SR4 or LM) but they are a hell of a lot cheaper and more robust.

[Count Johnny]

The last time I was directly involved with weighing things (2008) all wet without driver:

PR6 - From 471 to 500kg
SR4 - From 508 to 526kg
SR3 - From 575 to 603kg

[andylaurence]

Not much I can add to what's already been posted. A PR6 is the best option on the hills, but you won't get two people in it. There have been quite a few ADRs for sale, but there's not as many as Radicals. I can't say I'd be buying a Radical for sprints and hillclimbs if I wanted to be competitive. A Force SR4/LM is much quicker. There are a few new sports racers being built at the moment and Radicals (and my ADR) will not be able to compete with them. Get an 1100cc single seater - loads of 'em about and cheap as chips compared to sports racers. A set of cycle wings gets you into Sports Libre!

[splitpin]

Sound as a £ right on the money info and advice from the experienced fellas above.

If you want to hillclimb a Rad (and why not), pick LCM's brain as clean as he'll let you.

So basically, if you want to circuit race, you can also trackday and with two seats on those carry a passenger for pleasure or tuition. We started with an SR4 and (unlike Andy) there was a passenger way more often than not.

Radical UK Race Series i.e. Club Cup - competitively, the choice is basically an RPE engined 1475 SR3 or a 1340 PR6. That's it, nothing else is pointy end competitive.

More scope in such as 750MC BikeSports; multi-marque, but in terms of Rads (which numerically dominate by a long way), pretty well anything upto 1340 can be used (1500 in SR3) and tuning is allowed, but no forced induction.

[kartaphilos]

Thanks for the great advice everyone. It seems the ideal vehicle for circuits and hills is actually two vehicles. Single seaters for hills are tempting, good competitive classes. I do like the idea of a 2 seater for the circuits so I can get an instructor to bash some smoothness into me :-).

I guess I need to think about how to buy and store two cars or pick which disclipline I want to do more at the moment..

Matt

[LCM]

Count Johnny said:

The last time I was directly involved with weighing things (2008) all wet without driver:

PR6 - From 471 to 500kg
SR4 - From 508 to 526kg
SR3 - From 575 to 603kg

Yeh!

That sounds like the sort of values that I remember from that open kimono thread. Well recalled, I had them written down somewhere but can't lay a hand on them at the mo!

[andylaurence]

Do speed events in a single seater and get tuition in a school car. Simples!

[Count Johnny]

LCM said:

Yeh!

That sounds like the sort of values that I remember from that open kimono thread. Well recalled, I had them written down somewhere but can't lay a hand on them at the mo!

I still have the spreadsheet from when I was stupid enough to co-organise the expensive fiasco that was BESCR.

[LCM]

Count Johnny said:

I still have the spreadsheet from when I was stupid enough to co-organise the expensive fiasco that was BESCR.

Well hang onto it for the next time that reality counselling is needed around here..................

[DarcySmith]

LCM said:

Count Johnny said:

The last time I was directly involved with weighing things (2008) all wet without driver:

PR6 - From 471 to 500kg
SR4 - From 508 to 526kg
SR3 - From 575 to 603kg

Yeh!

That sounds like the sort of values that I remember from that open kimono thread. Well recalled, I had them written down somewhere but can't lay a hand on them at the mo!

520 for an SR4 with every option ticked!!

Darcy

[splitpin]

DarcySmith said:

520 for an SR4 with every option ticked!!

Darcy

Just for Matt's benefit, that's without your goodself.

Just shows how massively heavy those big pistons are

[LCM]

As the late, lamented Alan Stanniforth said to me "when you add all those super-lightweight options, all you've got is a heavier car".

[mabbott]

I keep hearing rumours of a black and gold PR6 coming up for sale...

[BertBert]

Ahh, when I saw the "mabbott" post, I just knew there was going to be a dodgy PR6 advert! Have you finally done it then?

[Count Johnny]

LCM said:

As the late, lamented Alan Stanniforth said to me "when you add all those super-lightweight options, all you've got is a heavier car".

Interestingly, the heaviest SR3 we ever weighed was Paul Steele's 'carbon fibre' bodied car at 620kg. Heavy stuff that carbon fibre.

[kartaphilos]

So I was discounting the PR6 but that is looking like a good option now, good on circuits and reasonable on hills. The only issue was having two seats but that isn't a must have (given the performance differences). How much would a reasonable PR6 go for, any particular year or spec I should be looking for. Do they all have the 1340 engine?

What's this black & gold one like then :-)

What's the average cost of an engine refresh? And how far can it go past 40hrs? If I totally blow up an engine how much for a new one?

[splitpin]

There's a sub £20K 2010 1340 advertised on ROC, I assume with no VAT on top on that one and roughly 'down your way' I think >

http://www.radicalownersclub.com/view-classified/2...