Weighed the Sr2 today
chris mason - 21/7/10 at 08:48 PM
After fitting the passenger seat and harness yesterday the car was finally ready for a weigh in 
All along i was hoping to get the final weight to around 550kgs, but no money was spent sourcing lightweight components, all the brakes are stock mx5
items.
The only weight saving item fitted was a red top 15 battery.
The cage adds close to 30kg's over the stock chassis and with the car running a car engine and gearbox, around 550kg's could have been
asking a bit too much.
So i was pleased to the see the scales showing the car with a finished weight, fully loaded with oil, water and 4 gallons of go go juice of
552kg's
Quite pleased with the result based on previous cars i've weighed, and the fact this one has a full cage too.
It now gives me a respectable 138bhp/ton at the wheels 
[Edited on 21/7/10 by chris mason]
richardR1 - 21/7/10 at 09:03 PM
Nice result that Chris. The car does look superb and was good to watch in your Cadwell video. Wonder how long that bhp/ton figure will remain the
same .............................
Steve Hignett - 21/7/10 at 09:14 PM
quote:
Originally posted by richardR1
Wonder how long that bhp/ton figure will remain the same .............................
It'll last until 5th Aug, 'cos at Oulton on the 4th, for some unknown reason, some cheeky ginger/bald headed Bat Fastard will jump into that
nice new passenger seat and completely shoot down that 138 brake per tonne!!!
richardR1 - 21/7/10 at 09:31 PM
quote:
Originally posted by Steve Hignett
quote:
Originally posted by richardR1
Wonder how long that bhp/ton figure will remain the same .............................
It'll last until 5th Aug, 'cos at Oulton on the 4th, for some unknown reason, some cheeky ginger/bald headed Bat Fastard will jump into that
nice new passenger seat and completely shoot down that 138 brake per tonne!!!
That will be something to look forward to, he does build a good car. Anyone know his ebay username to take a sneaky peak at his feedback for any MX5
turbo kit purchases
[Edited on 21/7/10 by richardR1]
McLannahan - 21/7/10 at 09:32 PM
quote:
Originally posted by Steve Hignett
quote:
Originally posted by richardR1
Wonder how long that bhp/ton figure will remain the same .............................
It'll last until 5th Aug, 'cos at Oulton on the 4th, for some unknown reason, some cheeky ginger/bald headed Bat Fastard will jump into that
nice new passenger seat and completely shoot down that 138 brake per tonne!!!
To about 0.000138 I'd say.....
franky - 21/7/10 at 11:00 PM
Thats not bad going, a good honest weight too. Some people always seem to day their car is less than 500kg without going near scales. I guess the
RR car is a fairly lightweight design so 550kg for a fully stripped out car isn't bad really.
MK9R - 22/7/10 at 07:52 AM
is that with you in it?
chris mason - 22/7/10 at 10:45 AM
quote:
Originally posted by MK9R
is that with you in it?
No, 552 with a driver would be a pretty good attempt.
Not sure on what other full caged car engined 7's weigh, but i'd be doubtful if any were as low as 450-470kgs, with exception of the westy
fw500 from a few moons ago.
Franky, the car's not really stripped out as such, it has the normal interior panels, tunnel etc that all other SR2's have.
Again the chassis isn't super light from memory i think with the cage it weighed in at around 101kg's
I reckon a stock roll bar'd car with an 893 blade engine in and few other touches could see the car end up with a dry weight around 400kg's,
not bad considering it's not the smallest of 7's and easily accomodates tall and large guy's.
Don't worry abour Oulton Steve, i'll get one of those bolt on electric turbocharges off ebay, that should give me another 30bhp
As for the Bhp/ton figure, at the minute i can see that remaining the same for at least another 2 weeks, after that who knows
I did have look at S2000 engines again the other day.........................................
phelpsa - 22/7/10 at 12:39 PM
400kg is a very difficult number to achieve! Caterham only just got under it with their ital-axled, superlight chassis'd, blade engined track
car.
Westfield managed to get the FW400 down to 400kgs by making it essentially a 2 seater formula 3 car... carbon monocoque, magnesium transaxle gearbox,
magnesium uprights with race car 3 stud hubs and wheels etc etc. No expense spared. I had the honour of going out in one the other week, it was
absolutely awesome
For comparison, my Aries Locost IRS with bike engine, full cage and no road gear came in at 460kgs wet when cornerweighted at Procomp. I was hoping
for less that 450kgs which should be achievable with some small weight saving measures
[Edited on 22-7-10 by phelpsa]
loggyboy - 22/7/10 at 12:54 PM
What engine is it to have 75bhp @ wheels?
[Edited on 22/7/10 by loggyboy]
chris mason - 22/7/10 at 01:09 PM
quote:
Originally posted by phelpsa
400kg is a very difficult number to achieve! Caterham only just got under it with their ital-axled, superlight chassis'd, blade engined track
car.
Westfield managed to get the FW400 down to 400kgs by making it essentially a 2 seater formula 3 car... carbon monocoque, magnesium transaxle gearbox,
magnesium uprights with race car 3 stud hubs and wheels etc etc. No expense spared. I had the honour of going out in one the other week, it was
absolutely awesome
For comparison, my Aries Locost IRS with bike engine, full cage and no road gear came in at 460kgs wet when cornerweighted at Procomp. I was hoping
for less that 450kgs which should be achievable with some small weight saving measures
[Edited on 22-7-10 by phelpsa]
Your right about 400kgs being difficult to reach without spending mega money, but the difference between the mx5 engine/gearbox and an 893 engine is
approx 100kg's and the full cage adds 30kg's, add in the weight of fluids in mine approx 20kg's ( i did say 400kgs dry )
and you end up with 402kg's for a blade engined car.
Now i'm the 1st to question weights banded around on the internet, but these are all tried and tested weights, not guesstimates
As for my engine Loggy, it's a 20 year old 1600 mx5 engine, provides plenty of entertainment and looks like in combination with the SR2 chassis,
it may punch above it's weight on trackdays,
but we'll have to wait and see on that one At the end of the day it's me behind the wheel
phelpsa - 22/7/10 at 02:02 PM
I recon the weight difference between a blade engine setup and a MX5 engine / box setup isnt as great as 100kgs once all is taken into account. A
friend of mine replaced the crossflow and type-9 in his westfield with a fireblade engine and that took him from 580kg to 520kg. I can't imagine
an MX5 engine and box being significantly heavier than a crossflow?
I guess there's only one way to find out... when's the 'blade engine going in yours then?
franky - 22/7/10 at 04:10 PM
I'm hoping for sub 650ish with my car, cage/m3 motor and comfy seats might make it a challenge though!
chris mason - 22/7/10 at 04:19 PM
Not sure on the crossflow/type 9, but the mx5 engine and box weigh in at approx 180kgs
I would hazzard a guess that a fireblade with a foot extra prop plus gear linkage would be around 80kgs.
As you say though there's only 1 way to find out
But it won't be with my car, my days of bike engines are behind me for a while, car engines is where it's at
I believe Road Runner are building an R1 powered Sr2 in the coming months though.
650kg should be acheivable with the m3, or is it a heavy lump? when i built the S2000 indy it weighed in at approx 625kg's, the engine and box in
that weighed around 194kg's
That said you mentioned a cage so 650kg could be a close one.
franky - 22/7/10 at 04:35 PM
quote:
Originally posted by chris mason
Not sure on the crossflow/type 9, but the mx5 engine and box weigh in at approx 180kgs
I would hazzard a guess that a fireblade with a foot extra prop plus gear linkage would be around 80kgs.
As you say though there's only 1 way to find out
But it won't be with my car, my days of bike engines are behind me for a while, car engines is where it's at
I believe Road Runner are building an R1 powered Sr2 in the coming months though.
650kg should be acheivable with the m3, or is it a heavy lump? when i built the S2000 indy it weighed in at approx 625kg's, the engine and box in
that weighed around 194kg's
That said you mentioned a cage so 650kg could be a close one.
Think the engine/box combo is about 180kg(thought the mx5 would be a lot lighter than that!? The m3 engine is the same weight as a vx red top but the
gearbox/bell housing is lighter than a type 9 etc.
To be honest sub 700kg should be doable with ease but 650 would be a nice target, however my seats are the padded type so there's 10kg over a grp
set
Big brakes and bmw calipers don't help much either but i'd look in the mirror before I chuck away money on the car!! just over 300bhp
pushing even 700kg at the worst along will still be quick enough and I can concentrate on getting it set-up for bends
procomp - 24/7/10 at 12:29 AM
Hi
Locost race cars are 615Kg with driver. So that's 530Kg without an 85Kg driver. Most are carrying ballast to get up to 615Kg. But that's a
race car with crossflow/ type 9 steel dampers steel hubs M16 calipers 16G chassis steel floor and full cage.
Cheers Matt