Locost vs Exocet

Because I thought you lot might find this interesting: we put a Westfield frame beside an Exocet yesterday. Very different solutions to a very similar problem. I do not yet have a weight on the Exocet frame, I'll measure that soon. I really should have lined up the back of the frames instead of the front, that would give you a better idea of the placement relative to the wheels. The standard Locost frame is basically a Westfield photocopy without the IRS.

The floors are level with each other, believe it or not. The Westfield does not have the roll bar bolted in.

can you re-align then so that the front wheels would line up? Give a different prespective of porportions, that way.

very interesting- I know a lot of people have CAD worked the "7" frame, but wonder what would happen if the same kind of effort that went into the X's frame would deliver some changes.

(BTW, its' an interesting optical illusion since the pallets you are using to hold them are so much different in size. Would be less odd looking if they were all the same size so that eye based measurements would be better).

Oh, and one other related question- is there a 7 set of plans that uses all of the Miata suspension? I suspect not, since the front's are kind of odd shaped. But if they used more same parts, it would be an even more interesting comparison.

The Westfield frame is back on top of the pallet shelves, but if I get another chance to pull it down for different alignment I will.

The Westfield is no larger than it has to be. The widest point is dictated by the space between the wheels in the rear. The Exocet swells. It really makes the Westfield look dainty.

No, you can't use the Miata front suspension on a traditional 7 frame because of the width of the chassis. The front control arms are much wider than the Miata. That's the sort of thing we're comparing here. People have used the subframe in the rear, though.

A few more.

I stared at that first pic wondering how the X was so stiff as compared to the 7. Then I got to the height, and it all made sense. I never realized that the 7 chassis was so low. That backbone must be necessary to compensate.

Not to risk the X guys, but it would be very interesting to see a head to head of the mostly miata based 7 vs an X- just to see.

My "guess" is that the X would be a little easier to drive, being wider, BUT I'm not sure if it would be faster. Just don't know.

Alas, I bet that isn't in the cards.

Thanks for taking the pictures, at least. Gives one a great idea of what you are getting!!

Tuna, you could also say the 7 frame isn't any higher than it has to be due to the backbone It really is just what's required and nothing more. Although I know which one I'd rather be t-boned in.

We've already done a back-to-back between the X and the 7 when we had Warren's car last month. They drive differently, the position of the driver has a big effect on that. The X really just feels like a Miata. A light one with great braking, yes, but it's got the same feel to it. The car pivots around the shifter and it's super-friendly. In a 7, you're on the back axle with a bit of rear weight bias, so you can really lay down power coming off a corner. You also have to manage the front grip of that light front end a bit more. It's not necessarily harder to drive, just a different style.

The width of the frames doesn't reflect the width of the track. The Westfield does have a narrower front track but the rear is identical. On my Locost, I've got a Miata front track.

In terms of lap times, the turbo Westfield has a best time of around 1:00.5 if memory serves. We didn't have a transponder on it the day the X was in town. The Exocet pulled a 1:01.9, and that was far from a sorted car at the time. I'd call them pretty even in terms of speed, setup is going to make the difference.

That's a neat comparison. Thanks Keith! I would build an exocet, but that's because I want to put a Honda B18 in the rear.

In terms of adding lightness, how different is the NC from the NB/NA? With the lighter powertrain, that may help a lot.

It's a different car. The powertrain isn't really that much lighter - what's an aluminum block worth on a 2.0 four over an iron one? 15 lbs? When we put the V8 in them, the weight change is pretty similar to the change in an NA/NB. Seats are probably heavier due to the explosive pillows, the car is physically bigger but was designed with more sophisticated tools, etc.

But we're into a different discussion than comparing kit car frames, it might be worth a new thread if you want to get into the usual "well, I heard you can take 200 lbs out just by replacing the seats" chat.

Clutchsmoke, I think there's an error in your statement. You're not going to put a B18 in the back of an Exocet. That's the yellow frame above, by the way.

In reply to Keith Tanner:

No, I'm wondering how much lighter it could be with a duratc 2.0l. It's more than 15lb, block to block.

But that's not important.

I came up with a number years ago after weighing a bare BP block and then using the relative weights of the iron and aluminum LS blocks to get a percentage difference. Engine weights quoted online tend to vary dramatically so I don't trust them.

Let me double-check.
- bare iron BP block, 67 lbs (just weighed it on our postal scales)
- LQ9 6.0 iron block, 170 lbs
- LS2 6.0 aluminum block, 110 lbs

Thus, an aluminum block weighs approximately 64% of an iron one. So that means you could save 23 lbs by changing the BP block to aluminum. You're in a better position to say exactly what a Duratec block weighs, but that's ballpark.

You'll note that I haven't posted any finished weights here. Roughly speaking, a Westfield and an Exocet built from the same mechanical base will be about 200-250 lbs apart - the Westie is lighter. The actual end result is going to depend on a lot of choices you make during the build, but the legitimate low end of weight for a car-engined Seven seems to be around 1150-1200 lbs wet, given all reasonable weight-saving efforts.

You guys don't have a roller yet? Sheesh, I'm disappointed.

Yeah, we have NOTHING ELSE TO DO.

Except post on GRM and Facebook, of course

turboswede wrote: Except post on GRM and Facebook, of course

Man... My dream kit car is a Locost built based on the dimensions of a Caterham. I've never been too excited by the Westfield and other kits. However, the price point on the Exocet is fantastic! The looks are the only thing holding me back...

Keith Tanner wrote: Clutchsmoke, I think there's an error in your statement. You're not going to put a B18 in the back of an Exocet. That's the yellow frame above, by the way.

Yeah not that frame pictured. For some reason my brain recalls reading about their other/previous frames. I think there's one you can put the engine behind the seats. I'll be realistic tho and say I probably wouldn't bother with the Honda engine setup after reading their recent updates on the frame you originally posted. I want to make it easier and faster to build just using a miata donor.

Joshua wrote: Man... My dream kit car is a Locost built based on the dimensions of a Caterham. I've never been too excited by the Westfield and other kits. However, the price point on the Exocet is fantastic! The looks are the only thing holding me back...

That amused me, because I never really wanted to build a Locost because of how they looked. Diff'rent strokes...

Joshua wrote: Man... My dream kit car is a Locost built based on the dimensions of a Caterham. I've never been too excited by the Westfield and other kits. However, the price point on the Exocet is fantastic! The looks are the only thing holding me back...

I'm with you in that my eyes say I want a Caterham clone, but my wallet and logical side say Exocet.

So the Turbo Westfield was 1.5 seconds faster than an unsorted Exocet. What motor did the Exocet have? Because if that was a stock Miata Mill, count me impressed.

kreb wrote: So the Turbo Westfield was 1.5 seconds faster than an unsorted Exocet. What motor did the Exocet have? Because if that was a stock Miata Mill, count me impressed.

It was pushing 220whp at the time. Base tune FM2.

The turbo Westfield has, on its best day, gone 1.4 seconds faster than the XP-3 Exocet did on its first visit to our track. That Exocet has an FM II and was putting down 220 uncorrected rwhp on the day, so it's actually pretty similar from a powerplant perspective. It also had some crazy alignment problems. FYI, my 148 rwhp Locost has managed 1:01.8 on the track, and that took some fairly committed driving and a fair bit of setup. I think the track has slowed since those days due to some new heaves in the track, as I'm about a second off that time now.

Clutchsmoke, an Exocet is a particular model of kit car. In the case of the one here, it's built in Altanta by Exomotive although they used to be imported from the UK. You may be thinking of a different MEV car imported by Exomotive. But an Exocet uses a Miata suspension and drivetrain. Just FYI, that might clear up some potential confusion.