Tractor

Been pondering this a bit. I plan on getting an Sti Type RA (version 2,3 or 4) in the coming weeks/months, and was curious as to whether there are many weight savings to be had anywhere.

I'd rather not remove the seats or spare, but will happily fit lighter wheels, lighter front seats and other components.

My question is, what suggestions do people have of places where weight can be saved? Does anybody know if there is a supplier of plastic/carbonfibre panels for the classic impreza? Are there any known parts that could easily be replaced with lighter items?

Would love to hear your thoughts. The earliest RAs are around 1200kg from memory. How much do you reckon that could be skimmed down to? Has anybody tried anything similar? I know a guy over on the Lancer Register pursued this fanatically.....

Tractor

Nobody has any ideas then?

flat4

remove the spare and fit tyre sealant, AC is fitted to STi RAs - remove it, fit a carbon bonnet/boot etc., remove the rear spoiler, remove the spotlights.......should be good for 30Kgs

there was great thread on this somewhere, might be in the projects forum

toofast toostupid

1208kg mine was I think ? I had the sti 2 V limited. These are seriously quick cars ! Remove the air con, I did'nt think they came with it but mine did ! Lighter exhaust ? one thing that will p**s you off is no electric windows or central locking that really did me in after a while, but I was using mine everyday ? remove the speakers ? or replace with light weight ones, these weigh a kilo or two each cause of the magnets !

rosswalker

Go on a diet Then you wont need to strip it out.

Tractor

I'll have you know Ross, that I am extremely 'streamlined'...... well not really, but I like the pies, so it'll be the car that goes on the diet!

Cheers for the replies guys. I'll have a look in the projects section.

Anybody know what I might save with some superlightweight 17" Alloys - 10kg maybe?

Sounds like I may be able to get rid of 50kgs with reasonable ease, but the rest would be a little difficult.

Andy.F

I had my RA down to 1170kg whilst retaining a full interior trim but that required removal of air con, speakers, power steering and fitting a small battery.
MY99 uk wheels are the lightest, super legs will save a further 0.5kg per corner but you could put that back on depending on tyre choice !

Andy

greasemonkey

This is a piece of string question. Not sure whether 1000kg would be a realistic possibility. To get anywhere near would be at considerable expense, and compromising the car's practicality as a daily driver.

Complete interior strip-out, motorsport seats, lightweight roadwheels, omitted spare, little battery, carbon fibre bonnet and bootlid would probably get you to around the 1100 - 1120kg mark.

Anything under that and you'd be looking at £££ for fabricated transmission and engine subframes, lightweight steel or composite propshaft, titanium/inconel exhaust (and a thin one at that), tubular headers, fabricated suspension arms, titanium or aluminium fixtures where applicable, lightweight radiator and intercooler, composite bumpers, WRC car thin front and rear windows, plexiglass side windows, maybe even plastic body panels. How far do you want to go, or, to put it another way, how deep are your pockets?

Tractor

In all honesty, not very! Thanks for your input. I would be happy with the 1100-1120kg that you mention and could probably afford that.

What I would love, would be to achieve a power/weight ratio of 300bhp/tonne, and figured that there would be a cost sweet spot/balance to achieve this by pursuing weight reduction AND modification. Moreover, I love light weight cars, and all the performance, handling, braking benefits that come with them. By saving 100kg, I would not have to upgrade the brakes so much , for example, as losing weight achieves the same goal.

To get 300bhp/tonne at default 1200kg weight would require modifcation to 360bhp, which would be expensive and has all the associated reliability and running cost downsides. However, 1100kg requires 330bhp, which would cost less. The question is, what is cheapest in the long and short term, tuning from 330bhp to 360, or losing 100kg in weight? A more achievable, practical (allowing me to retain a full interior for example) and cheaper compromise would be 1150kg, which would need 345 bhp to get to 300bhp/tonne. In any case, I may have to settle for a 'mere' 280bhp/tonne or so to save some cash. We will see, and it is fun to speculate. I am aware that the lighter I go of course, the more my own weight will damage that 300bhp/tonne figure!

My first task is to find the right car. I am thinking Sti version 3 Type RA as this gets me the 4 pot brakes, facelifted front (easier to find light bonnets for) and allegedly most tunable engine. Version 4s are that bit more expensive, and Version 2s have quite a bit lower spec. I'll probably source one in Japan as I think there are some big savings to be had, although haven;t checked into this too much yet. I am familiar with the UK prices of such cars having had three classic Stis

All opinions welcome so please keep them coming. If anyone can recommend a decent importer (or Japanes exporter ideally) I would be very grateful.

Thanks again

Mike

MorayMackenzie

Version 4 would have the newer style interior with airbags etc... which would, IMHO, add to the weight.

MorayMackenzie

Iain Litchfield (Litchfield Imports) sourced my STI 3 type RA V-Limited, and I was very happy with his service.

Tractor

THanks Moray, I was thinking Version 3 too for the reasons you state, but the non V-Ltd as these often have leccy windows, central locking etc iirc. Would you mind if I asked how much you paid through Ian for that car, and when this was? PM me if you'd rather not discuss online.

Many thanks

MorayMackenzie

Hi Tractor,

I don't think the price would be of any help at all as I bought the car five years ago. Prices have changed somewhat since then.

Moray

Adam M

I think the price difference in tuning at 330 and 360 is negligible.

I would aim for 360, ask andy f about cheap tuning, and save as much weigth as you can as described above without incurring any costs, The weight reduction has mroe advantages than the power hike, but 360bhp can be achieved quite easily.

Tractor

Cheers Moray and Adam.

Adam, do you know how I can get hold of Andy F? Any idea what it would cost/what I'd need to get an Sti 3 RA to a nice reliable 360bhp then?

How's the 22B by the way?

Ta

Mike

Keigo

Lightened Pulleys (save 5-7 kg), lightened flywheels (save another 5kg) also really affect the acceleration positively due to their nature.

keeping your eyes on fuel level will also help - too much fuel, too much weight.

You might want to move your battery to the rear of the car for weight balance, too.

If you have airbag steering wheel, swap it for a light Momo racing wheel, and also passenger airbag can be removed. Also, anything electric will come with surprisingly a lot of wires, which will come to a fair bit, so if you don't need things like electric windows, central locking, then take the whole lot off.

If I can think of other things, I'll post again later.

MorayMackenzie

I would steer clear of lightened crank pulleys, I don't know of one which retains the harmonic damper function of the standard crank pulley.

dowser

Do you know anyone who's suffered negative results from using one though?

Richard

MorayMackenzie

"Do you know anyone who's suffered negative results from using one though?"

No, I do not yet know of a definite EJ series failure that has been tracked back to the removal of the harmonic damper, however, I do know what the harmonic damper is designed to do and I do not consider it redundant.

dowser

Thanks Moray. Would be interesting to know how many are in use out there, and how many have suffered engine failures. I have a vested interest in that I'm building my ej25 with a Perrin lightened item.

What is the purpose of the balancer/damper? I initially assumed it was to remove/dampen shock loads between crank and other components attached to the belt. But this is rubbish considering the belt itself also has a certain amount of play too? And why is it so damned heavy?

Thanks, Richard (sorry for dragging this off topic)

MorayMackenzie

The Damper is to keep torsional vibration under control. As the engine runs, the pistons apply torque to the crank in a sequence of pushes. These push cycles actually cause the crank to twist and untwist(rebound) as it is being driven, this twist/rebound sequence is known as torsional vibration. The whole crank is subject to a continuous sequence of these torsional vibrations.

If left uncontrolled, these vibrations will, at the least, contribute to shortened crank bearing/journal life, and at the worst, cause catastrophic crankshaft failure.

The harmonic damper is fitted to keep this torsional vibration under control by converting some of the vibration energy into heat in the dampers rubber damping ring as the rubber "absorbs" some/much of the torsional vibration.

MorayMackenzie

You may find the following write up of interest, although it does relate to a different engine, the principles are the same.

http://www.pacarsearch.com/stealth/udp.htm

AndrewC

I haven't got a link, but I remember reading on one of the US boards (possibly the Cobb forums) describing some testing that identified the specific harmonic that the EJ20 crank pulley dampens and why Cobb do not recommend the use of lightened pulleys.

Does anyone know where I could obtain just an underdriven alternator pulley?

Andrew...

dowser

Thanks Moray - bang goes my "ignorance is bliss" approach then Time to discuss with my builder......

Richard

Andy.F

FWIW, Harveys 500+bhp 20,000 miles+ daily driver/racer does not use a vibration damper and has had no crank/bearing issues whatsoever :-)

911

Interesting read.
It was me who posted this thread on Projects about 6 months ago, all lost now the Snet has changed(for the worse I think)
I had a lot of very practical suggestions to get to the magic 300 bhp/tonne. To get to the 1000Kg mark will take a lot of doing, and very ££££££££££££££££.

The Sti RA v3 is a great start, I have a hill climb Sti v3 with 314 bhp, so getting close.

Best way to get closer is to simply buy Carman's RA (see Cars for Sale). Thats 350 bhp, all the right basics for a ballistic car, and light too! I've driven it in anger, fab car. Too bloody cheap, buy while it is still there!
911

trolleydolly

don't forget the weight of the wheels, mine are only 6.9 kgs per 17" wheel, stock is probably double , at least on european imprezas ( and then x 4...).

the heavy (cast)iron brake calipers can be replaced by aluminium ones, stock are also very heavy!

Cord

Moray's point are very valid and the reasoning behind them is spot on, but there are now quite a few high mileage high horse power cars knocking about with no crank/bearing issues, maybe a problem will appear after very high mileage, but bearing life will be shortened anyway by me putting 450bhp through them. So I don't expect my bearings to last forever, and fully expect I will be opening the engine up to replace bearings anyway (as long as I haven't put a leg out of bed before then!!!). Subaru cranks seem fairly strong (anybody heard of any snapped ones??) And the belts and accesories driven by them do absorb some of the torsional vibration, so i am quite happily fitting a light weight, under driven, damperless pulley to my engine.

And on the topic of lightening, who does carbon bonnet/boot for 99 cars? And are they any good (quality strength weight?)

Tim W

iTrader: (1)

Back on topic I seem to recall that the standard Subaru 'buckets' weigh in at an impressive 35kg apiece replace the two fronts with a pair of light weight buckets and there's potentially around 50kg saved

Stripping all the sound deadening and underseal from one car I know saved around 30kg too