Duncan,
I've
just advised Mick that he should be OK up to 11:1 on Optimax and along comes
your problem (sigh). I'd be looking at finding out exactly why you're pinging
before just pulling everything apart and lowering the CR, cause guess what, it
may not fix the problem and then what do you do. Strokers
typically had this problem at sea level and I'm thinking that your
combustion temperatures must be high for some reason. I'd be looking at the
choke and jets sizes, may be try some 38's, it's an urban myth that strokers
have a lower demand for air (cfm) than a rever so it could be leaning out. 4000
rpm suggests that it's around max torque which supports my theory and you should
be able to run 35 degrees max advance. Have you run the engine at night in
cooler air, if so was it better/worse/no different. If it's better I'm on the
money, if it's either of the other two then I'm clasping at straws. Cam timing
will affect combustion pressures, the general consensus was to run on P2 (my
pref) or P3 but never retarded.
Have
you had a dyno run, I know it can be exy but it the easiest way to simulate road
conditions that I know to find out what's going on inside an
engine.
regards
Terry
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Duncan Shillito
Sent: Wednesday, 30 January 2002 11:27 AM
To: [EMAIL PROTECTED]
Subject: Re: HELP - comp ratio>From: andrew smith <[EMAIL PROTECTED]> >Reply-To: [EMAIL PROTECTED] >To: [EMAIL PROTECTED] >Subject: Re: HELP - comp ratio >Date: Wed, 30 Jan 2002 07:41:31 +0800 > >Duncan, >Has the combustion chambers been radiused and what heat range plugs are you using.Did >they use a high speed timing light to determine the total advance.What cam is in it >and do you know the close point on the inlet,sounds like the cam might be to small >for the comp ratio or just closing to early on the inlet.Maybe your right and you do >have to much comp but there's plenty of L series around with that much comp running >34 or more ignition timing.What head are you using cause you maybe able to squeeze a >few cc's out of it by deshrouding etc. >Andrew Smith > >SHILLITO Duncan wrote: > > > Hey guys, > > > > I know this topic has been visited over and over again, however after > > much fiddling and experimenting I need a little more help. > > > > I have approximately 10.9:1 compression ratio in my 2.3L L series (full > > house). The engine is pinging severely from about 4000 rpm onwards. I'm > > using 98 ron optimax fuel with a total of 28 degrees advance timing ? > > retarded to stop pinging, but is very sluggish. > > > > I believe my goal is to reduce the comp ratio to about 10:1, so I can > > get maximum power using more advance of 36 deg. My options are: ???? > > 1. Remove the head and add the appropriate steel > > decompression plate to reduce the comp ratio. However these extra > > gaskets hinder the swirling effects required for optimal burning and are > > likely to leak oil and coolant. > > 2. If possible remove more metal from the head to reduce > > the comp ratio. This may be expensive and also hard to achieve since the > > head has already been shaved 30 thou and has 44mm inlets valves. > > 3. Add toluene (methyl benzene) from shell & optimax at the > > cost of about $1 per litre. (with webers this equates to about 7km/$ = > > V8 territory hehehehehe). > > > > I have to pull the head off now anyway due to a water leak - so I need > > some quick fire assistance if possible. I've just had a tune diagnosis > > completed (using optimax) and air : fuel ratios didn't change or reduce > > the pinging. > > > > Also, what cost and where can I buy some 36mm chokes for my 45mm webers > > ???? I'm on the Gold Coast. I believe that 38mm are too large for the > > stroker - max hp at 5250 rpm and I'm sure 36s will help with higher > > velocities into the head (see ? bernoulli's theorem can be put to good > > use). hehehe > > > > Thanks for any help.........much appreciated > > > > dunc. > > > > Duncan Shillito > > Technical Officer > > Reticulation Services > > Gold Coast Water > > Mob: 0414 180 775 > > e-mail: [EMAIL PROTECTED] > > > > > > > > > > ********************************************************************************* > > This e-mail and its contents is confidential to Gold Coast City Council > > and un-authorised use is strictly prohibited. > > ********************************************************************************* > > > >--membersozdat------------------------------------------------------- >OZDAT Mailing List Please Note:- >Send (un)subscribe requests to [EMAIL PROTECTED] >Send submissions to [EMAIL PROTECTED] >No unauthorised redistribution of this email >http://www.ozdat.com/ozdatonline/index.htm >http://www.ozdat.com/ozdatonline/listindex.html >http://www.mail-archive.com/[email protected]/ >---------------------------------------------------------------------andrew,
as far as i can tell the cam is timed correctly (advised by ivan tighe cams in brissy). it is a 76 works grind. i'm using standard ngk plugs. the combustion chambers have been relieved around the heel of the valves - however i think i'll take it to the local head shop and get some advice. i like the idea of increasing the head chambers. see what happens.
thanks,
dunc.
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