Lotus Elan

prepping a tranny (and a racing Elan)

PostPost by: rgh0 » Thu Mar 17, 2005 9:46 am

Peter

I guess I have gone down the same route of you for much the same sort
of reasons, however I have done it progressively over 20 years and
found what breaks and what does not by experience. The internet and
this sort of group did not exist when I started unfortunately as it
would have saved me a bunch of money! At least in my historic racing
class in Australia the 356's and early 2 litre 911 are not a problem
legal or not. Its just the mid 70's 3 litre Carreras with $100,000
engines I struggle with. But my mate in his S4 7 with a little less
weight and little better handling has their measure as well !

Your engine may be good for 9000rpm but I would recommend a rev
limiter set at around 8000 to 8500 to avoid prematurely shortening
its life. It will rev to well over 9000 in a fraction of a second
with a missed gear change and at 9000rpm plus the life of bearings
and other components is getting very short and valve bounce becomes a
problem.

With a serious 170 plus hp engine and track work on reasonably sticky
tyes ( I use YOKO A032R soft 175 X 60 and Hoosier Street TD 185 X
60 ) you will start to break things in the drive train. Gear box as I
have said, diff output shafts, rear hub shafts and the original
wheels. Replacement of donuts with CV's or equivalent is a given. All
need replacing with stronger components. If you stiffen the springs
and shocks for better track handling then you wil start to bend and
crack the chassis and this will need strengthening also. The rear
hubs may also start to crack but that probably relates more to the
number of times you have them on and off the shafts. You also really
need a LSD to put the power on the ground coming out of a corner.

Oil surge is an issue and you need good sump baffling and an overfull
sump, or an accusump or a dry sump to get you through long tight RH
corners without loss of oil pressure, especially ones you accelerate
up to with little braking.

Also you need lots of detail work on the engine to actually keep a
high revving high hp twincam engine running properly and not break. I
have had issues with alternators, oil pumps and dizzies due to
vibration at high revs in the engine.

As you say a viscous circle or as I view it a never ending challenge
to build a a reliable racer at a reasonable cost. I have a new and
what I hope will be 180hp plus motor on the stand now. I am sure it
will show other weaknesses to be tackled in turn.

Staying with less than 7000rpm and say 145 to 150hp is certainly
easier but not nearly as much fun. Even at these lower power and rev
limits many of the other issues still need to be tackled. Good luck
wih your project and happy to talk about any or all of the issues you
will need to tackle

regards
Rohan

--- In ***@***.***, Peter Steilberg <[email protected]>
wrote:
Rohan: Actually -- I don't know how I ended up in this situation.
I wanted

to build a really really reliable elan racer. Something fast in a
vintage

context to play with all the illegal 356 porsche's.

So now I have a $15,000 all steel motor good to 9 grand and 170 hp -
- stage

three. I want to race occasionally, drive occasionally, and just
have fun,

but not worry about my engine popping a cork! So now it goes like
this. If

you have elan, you need the motor, then you need the sump, then the
drive

shafts, then you need the diff mountings, then you need the wheels
blah blah

blah. Then at a certain point it sounds like, hey now you have a
170 hp

race elan and its gonna break the gearbox -- either because of
power or

because of rpm. Then, even if I move to a dog box, I'll break that
cuz I

can't shift. Yikes. I should have stuck with 7000 rpm.

Now, I hear that you can't do turn 3A at Pacific Raceways without a
drysump

or it'll smoke the motor.

It's a vicious circle! I tellya! ;-)
In God I trust.... All others please bring data
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rgh0
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