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XI with an R1 bike engine


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MK11
On 04/08/2020 at 16:15, Ortekk said:

 

It feels like it would understeer like an Vauxhall Vectra VXR...

 

 

When I had my XI on a handling circuit it was the best fun I have ever had.  On the hard skinny 155 tyres fitted to wire wheels it was proper fun.

 

On my car the front end was very pointy, unless I was really pressing on, it went exactly where I wanted.  If I pressed on a bit harder then you went into proper old school 4 wheel drift steering on the throttle.

 

I miss that car soo much. It ended up in Finland and I bought an Ultima GTR.  Unfortunately, faster did not equate to more fun so I sold it again.

 

 

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When I had my XI on a handling circuit it was the best fun I have ever had.  On the hard skinny 155 tyres fitted to wire wheels it was proper fun.   On my car the front end was very pointy,

I'm also a huge fan of 'road' tyres for track use, particularly on light cars.   As MK11 says, they are a lot of fun, with a wide operating range from grip to slip, wear surprisingly slowly,

This is where the engine will sit, the sump is flush with the gearbox hoop, even though it looks a lot lower! The silvery cookiebox thingy is actually the Oil cooler! It's cooled with the coolant, s

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robhume
23 hours ago, Ortekk said:

Seems like I won't gain anything from going wider then, good to know! Lets hope I find a decent rear axle :)

How is the clearance at the front with 185 tires? Will I need to limit steering further going that wide, or is there enough room?
175 are difficult to find and 185 are cheaper for me. 
 

As for the spring rates, I will do proper calculations once I get to weigh the car. I'm looking forward to see the weight distribution, BEC and LHD usually don't mix that well, hoping that putting everything I can to the right of the chassis will make enough of a difference.

 

Regarding your question about front clearance with 185 tyres.  I used hose clips on the steering rack for the "stops" either side as I could adjust

the position to suit. My car is not road registered and have not found a problem with clearance on track, even with a tight hairpin bend but, generally the turning circle is pain. I'm sure the other chaps who have road registered XIs will give their experience.

 

 

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Ortekk
15 hours ago, MK11 said:

 

When I had my XI on a handling circuit it was the best fun I have ever had.  On the hard skinny 155 tyres fitted to wire wheels it was proper fun.

 

On my car the front end was very pointy, unless I was really pressing on, it went exactly where I wanted.  If I pressed on a bit harder then you went into proper old school 4 wheel drift steering on the throttle.

 

I miss that car soo much. It ended up in Finland and I bought an Ultima GTR.  Unfortunately, faster did not equate to more fun so I sold it again.

 

 

Where you running vintage racing tires? Pretty hard to find narrower tires than 175 that isn't OEM fuel efficient tires or a random chinese tire.

I became interested in the XI after seeing the Lotus 11 and 15s sliding around at Goodwood, sounds like I'm building the right car when the XI is similar :)

9 minutes ago, robhume said:

 

Regarding your question about front clearance with 185 tyres.  I used hose clips on the steering rack for the "stops" either side as I could adjust

the position to suit. My car is not road registered and have not found a problem with clearance on track, even with a tight hairpin bend but, generally the turning circle is pain. I'm sure the other chaps who have road registered XIs will give their experience.

 

 

I've mounted hose clamps on my rack as well, Westfield supplied two cut pipes that was too small to fit the steering rack...
Did you simply reduce the lock further?
I'll hear what my IVA guy says, but don't think it will be a problem with limited steering lock :)

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AdamR
12 minutes ago, Ortekk said:

Pretty hard to find narrower tires than 175 that isn't OEM fuel efficient tires.
 

Nothing wrong with these btw. They are surprisingly good.

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stephenh

When I built my XI (which I haven't got anymore) I did quite a bit of research into suitable tyres, and ended up putting Dunlop Street Response 2 tyres on. Plenty of grip for fun road driving, and even the occasional track day. IIRC I fitted 165/65x13" size. I had lock stops, which I had made out of polypropylene. The length of the stops was 5mm. less than the Westfield build manual recommends, and I had plenty of clearance both sides. Yes, the steering lock was aweful by modern standards, but still manageable.

For what it is worth, I also calculated that I would have sufficient clearance to fit Kumho V70 road legal trackday tyres if I ever wanted to do more serious track use in the car. I just need to check what size I worked out would fit, and I'll edit this post.

 

edited to add: Yes, it was 165/65x13" Dunlop Street Response 2 tyres. I can't find the info for the trackday alternative (which I never actually used in the end) but I suspect it was 175/60x13" which are unusual, but I think still available in medium/hard compound from Kumho or Nanking.

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MK11

My tyres were boggo Midget tyres 155/80/13 Avon CR322 from memory.  After a day on the handling circuit the tyres were only slightly worn compared to the normal Westfield's running on trackday slicks that went through a set of tyres per event.  Plus my tyres were circa £30 each.

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Ortekk

This surprises me a bit, in a good way! I was convinced that I would need R-tires for the track.

 

The experiences I've had with "cheap" tires has always been underwhelming. I guess the light weight helps a lot.

 

The R-tires should get faster lap times, but maybe that's not the way to drive a car like this?

 

I'm surrounded by quite serious Time attack cars in my garage and have friends who rave about using barely legal tires on the streets.

 

It's nice to have a different perspective on things :)

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MK11

The joy for me was in the gap between just losing adhesion and spinning like a top “stick or twist”.  With the XI on hard tyres the gap was huge and extremely fun (plus consumables were cheap).  Sometimes I think that some of the joy is missed when you chase ultimate lap times on ultra sticky tyres.

 

Back when I built my car Evo included the XI in their track day car of the year review.  Up against Caterhams, Atoms and the like, from memory it came third or fourth in the roundup.  But what sticks in my memory was that the XI did the most miles on track compared to all the others because people loved driving it. Then, of course, Evo went and built their own XI.  It is possible that the Evo review is still on YouTube somewhere.

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AdamR

I'm also a huge fan of 'road' tyres for track use, particularly on light cars.

 

As MK11 says, they are a lot of fun, with a wide operating range from grip to slip, wear surprisingly slowly, cheap, work in all weather conditions...

 

I currently use Uniroyal Rain (Expert or Sport, can't remember) tyres in 185/70R13, in a sub 400kg car with just over 200bhp, and don't see me changing any time soon.

 

Here's a video playing with @maurici who also follows the same tyre theories 😁

 

 

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maurici

Love this video @AdamR Hope we can repeat this at the end of the month in oulton.

I´ve been told that there is a significant ammount of people is being converted to our cult, and most of them will have their maiden baptism... .

 

Road tyres will be 3 or 4 seconds slower per minute than propper sticky tyres in our cars... I can´t see the point on wasting money and consumables in a trackday for this 3 or 4 seconds. And you get an amazing level of skill and control.

 

Then you turn up to a Sprint day, you cuck some decen nankangs and is suddently feels like cheating. you can push forever without losing the car and you are indeed much much quicker out of the box as it feels easy.

 

I have two sets of semislicks to burn at home (dated) and a set of race tyres... gess what? my continental eco contact are the ones that do most of the car´s mileage in and out of track.

 

I should copy paste this text by the way... is a rather recurrent topic.

 

 

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AdamR
2 minutes ago, maurici said:

Road tyres will be 3 or 4 seconds slower per minute than propper sticky tyres in our cars...

 

I've found even closer than this, more like 2s, but I guess that isn't the point!

 

Yes, really hope we get to play again and your camera works this time 😄

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stephenh

Good quality ordinary road tyres give plenty of grip these days, as long as the temperature is above about 7 degrees centigrade. The only thing is that they do tend to be rather hard for very light cars, so the idea is to chose a tyre which is by road tyre standards quite soft. Those tend to be tyres which have a good rating for wet use, which was why I chose Dunlop Street Response 2. I haven't used the Uniroyal tyres recommended by Adam, but assuming they are available in the right size for an XI I'm sure they would be quite soft as they are specifically a wet weather tyre.

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MK11

Turn left to go right.  That’s what I am talking about 👏

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RICHARD+PHILIP

Sprints/Hillclimbs are far more fun on 1A Tyres.  

 

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the stoat
On 08/08/2020 at 12:36, maurici said:

Love this video @AdamR Hope we can repeat this at the end of the month in oulton.

I´ve been told that there is a significant ammount of people is being converted to our cult, and most of them will have their maiden baptism... .

 

I too may join your cult, I use slicks while on track with the Westfield due to being tight and using 2nd hand ones.  However the most fun I have had on track was in my partners mk2.5 MX5 on skinny hard rubbered road tyres.  Wet and dry it had me giggling like a child and given it was predicable you had the confidence to really push on.  Given said partner is tremendous and generating tyre heat, she melted my 'wet weather' AO48s on a wet track, so time to try something cheap and road focused.

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