angus.d
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| posted on 6/7/06 at 11:56 AM |
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BEC Engine and Diff Choice
My first posting so sorry if this is going over old ground.
1) For cost versus bhp the 1litre Yam R1 or GSXR1000 engines appeal to me but it seems that loads more BEC builders have gone for the R1 motor. Any
reason for this or disadvantages with the GSXR motor ?
2) Which diff and ratio would work best with the above motors ? Sierra, Freelander etc ?
Any help greatly appreciated. Haven't started my build yet, just trying to get as much info to avoid costly mistakes !!!
Cheers
Angus
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yorkshire-engines
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| posted on 6/7/06 at 12:07 PM |
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Hi Angus i sell loads of both types of motor kits and the r1 is popular because of the ease of fitting and only the need to fit a sump baffel
the gsxr is a good motor and may require a sump mod however if you look at mk,s gixxer powered car you will see that no mods have been made to
this engine
your close to me so if you want call down and ill show you all the advantages of both motors
cheers malc 07960011585
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chockymonster
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| posted on 6/7/06 at 12:32 PM |
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quote:
Originally posted by yorkshire-engines
if you want call down and ill show you all the advantages of both motors
Malc is a top bloke and his engine kits are really good value.
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peterriley2
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| posted on 6/7/06 at 01:26 PM |
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freelander diff are the best- lightest and a good ratio, but need adapting to sierra uprights/hubs (im assuming your using a sierra donor). a sierra
3.38 diff is the best ratio all round, but 3.62 lsd is also an option. freelander diffs can be around £800, and sierra 3.38's around £150.
personally i would and am going sierra (unless i can find a scrap freelander)
Joel
If you dont respect yourself, dont expect respect from anyone else
Live your dreams, dont dream your life
Women only want you for one thing- everything!
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smart51
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| posted on 6/7/06 at 01:28 PM |
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I have a 98 R1 with a 3.62 diff and 195/50/15 wheels and tyres (these are interchangeable with 205/60/13s I believe). This combination gives me 50 in
1st, 70 in 2nd and 120 in 6th at the red line. I find it to be great.
A 3.92 diff would give more acceleration but lower top speed in each gear (111 MPH in top)
A 3.38 diff would give less acceleration in each gear but more top speed (129 in top)
A 3.14 diff would be the same but more so (138 in 6th). Whether you'll have enough power to make it to 138 is another question but peak power
at 10,500 RPM would be 124 MPH and I guess you'll get faster than that.
[Edited on 6-7-2006 by smart51]
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fesycresy
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| posted on 6/7/06 at 01:38 PM |
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You'll find the majority of people have gone with the 3.62, mainly because it's an LSD and the rear beam can be taken complete from a 4x4
with the disc brakes.
Unless you go to a fast track, then a 3.62 would be fine. The alternative would be a hybrid diff between the 3.62LSD and the 3.38 open diff.
You would probably need busa power and up for the 3.14.
-----------------------------------------------------------------------------------------------------
The sooner you fall behind, the more time you'll have to catch up.
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peterriley2
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| posted on 6/7/06 at 02:56 PM |
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thanks for the expanded explanation, ill also add that there is a 3.38 lsd, very very rare but it could be found with a large enough budget. on the
other hand, if you get a 3.38 and an lsd (3.62 or 3.92) you can pay around £100 for them to be mated together, although the lsd adds a bit of weight
(around 8-10kg i think) so if your going minimal weight keep this in mind.
also just to throw another spanner in the works, i must point out that the lsd in sierra's isnt a very good one, and there are places that make
better lsd diffs- quaife and others.
Joel
If you dont respect yourself, dont expect respect from anyone else
Live your dreams, dont dream your life
Women only want you for one thing- everything!
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angus.d
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| posted on 6/7/06 at 03:21 PM |
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Thanks to everyone for your advice.
On the subject of LSD diff I've been told that it's virtually a 'must have' item because of the cars power/weight and the
tedancy for spin up of the inside wheel under acceleration round corners.
The sierra LSD (XR4x4 etc) is I believe a viscous coupling and so isn't easily adjustable or progressive but on a positive note relatively
cheap.
The other types of LSD are mechanical such as ZF, or Quaife ATB etc and my understanding is that these are probably more progressive (ie. not snatchy)
however are very expensive (probably approx £1000 eek !!!)
Cheers
Angus
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peterriley2
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| posted on 6/7/06 at 03:33 PM |
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an lsd on a bec is certainly not a must have item, they are so light that they sail around most corners thrown at them, and i was told it would be
better to save the weight and hassle and go for a 3.38 non lsd (for an r1 bec).
Joel
If you dont respect yourself, dont expect respect from anyone else
Live your dreams, dont dream your life
Women only want you for one thing- everything!
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DIY Si
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| posted on 6/7/06 at 03:37 PM |
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I've recently taken ownership of an Indy bird, and have to say it's possible to spin the wheels, but you do have to try at it. I've
just got an open 3.38 (i think) and it's fine so far.
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andyharding
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| posted on 6/7/06 at 03:54 PM |
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I have a lot more torque than these little bike engines and can easily have the inside wheel smoking when going round a corner. I'm going to fit
an LSD as soon as I figure out how (I have push in shafts and can't find a matching LSD).
Are you a Mac user or a retard?
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JoelP
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| posted on 6/7/06 at 04:04 PM |
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i got a freelander diff for 150 off ebay. Im sure you can find cheap ones in scrapyards.  Its 6kgs lighter than a sierra diff. I also would agree
that an lsd is certainly not essential in a bec, or at least in my zx9 one. Maybe more powerful cars would benefit. In mine, the extra weight would
cost more than it would save me in corners IMHO.
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Pezza
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| posted on 6/7/06 at 09:46 PM |
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quote:
I'm going to fit an LSD as soon as I figure out how (I have push in shafts and can't find a matching LSD).
I converted my push in shafts.
Cut the outer casing off the diff end then just remover the c-clip and the tripod joints slide off.
CV joints fit straight on, replace the c-clip, repack with grease and put boot back et voila!
I did it rather than change my whole rear setup to disks etc as I wanted a LSD.
You couldn't pwn your way out of a wet paper bag, with "PWN ME!!" written on it, from the "pwned take-away" which originally contained one
portion of chicken tikka pwnsala and the obligatory free pwnpadom.
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andyharding
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| posted on 6/7/06 at 10:42 PM |
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I thought about doing that but then I wouldn't be able to remove the drive shafts through the hubs anymore so the "big nut" would
have to come off each time...
Are you a Mac user or a retard?
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Pezza
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| posted on 7/7/06 at 07:27 AM |
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There is that, I reasembled mine in situ.
You can unbolt from the diff if you need to remove it but have to remove the rear upright too if you want to move the shafts about.
You couldn't pwn your way out of a wet paper bag, with "PWN ME!!" written on it, from the "pwned take-away" which originally contained one
portion of chicken tikka pwnsala and the obligatory free pwnpadom.
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andyharding
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| posted on 7/7/06 at 08:47 AM |
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quote:
Originally posted by Pezza
There is that, I reasembled mine in situ.
You can unbolt from the diff if you need to remove it but have to remove the rear upright too if you want to move the shafts about.
I'm using a DeDion so my "uprights" are welded to the axle tube
Might do it anyway. It's not like the shafts come out every week...
 
Pre SVA Prep 5
[Edited on 7/7/06 by andyharding]
Are you a Mac user or a retard?
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scoobyis2cool
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| posted on 7/7/06 at 12:03 PM |
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Hi Angus, if it helps make your mind up a mate of a mate has just written off his GSXR1000, the bike is a wreck but the engine is still in good nick,
if you're interested I could get you his contact details?
Pete
It's not that I'm lazy, it's that I just don't care...
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angus.d
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| posted on 7/7/06 at 01:32 PM |
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Cheers for the offer Pete, but at the moment I haven't definitely settled on the choice of engine.
Even more confusing for me is that bike engines from the same model of bike seem to change (could be minor or major changes) every couple of years so
I'm trying to fathom out not only what engine I want, but also what year of engine would be better for a BEC or whether or not it really makes
much difference ?
I really want to find out which bike engines are best suited to installation in a LSIS car with the minimum headaches (for example do you need to
baffle the sump or dry sump, does the sprocket/output shaft line up well for the prop, would the carbs/TB's stick up through the bonnet with
possible SVA issues etc.
I do however appreciate the thought.
Best regards
Angus
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ChrisGamlin
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| posted on 7/7/06 at 09:01 PM |
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Least hassle will definitely be an R1 out of the two you've mentioned. 98-01 engines are pretty much identical, ~150bhp, run on carbs and only
need a baffle plate to be safe for track use.
02/03 engines are virtually identical to the earlier engines, but run fuel injection instead. They have similar power output but a slightly fatter
mid-range, and again they only need a baffle plate to be track safe. Some say the injection engines are harder to get through SVA emissions but I
suspect those saying that decided not to use a Power Commander (~£200) to give you far more control over the fuelling than either carbs or standard
injection can give you.
On all these engines prop angles are about the best you'll get with any BEC due to the stacked gearbox on the R1. It will stick through the
bonnet a bit though, but you'll be very lucky to get any BEC under standard "book" bodywork, I just about managed it with my blade
engine and a severely chopped sump, but even that wasnt ideal as the air filter was squashed up against the underside of the bonnet.
Anything newer than 2003 though and you're sailing more uncharted territory as the engine design changed significantly with the 2004 model year
and not many people are running those engines yet.
As for the Gixer, as mentioned there's a couple of examples running round on track with wet sumps that dont appear to be having issues, but
several front engined RGB (BEC race series) runners tried various wet sump mods with these engines a couple of years ago and couldnt stop them
exploding without dry sumping, so I suspect that the current track cars that appear to be OK so far are sailing close to the wind and/or not being
driven anywhere near as hard. Either that or the very new engines (if being used) are more wet sump friendly.
cheers
Chris
[Edited on 7/7/06 by ChrisGamlin]
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