Individual Cylinder Tuning
I would like to invite your attention to the following:
SAE paper 890044 Saab Direct Ignition system and its cold start
performance.
SAE paper 950004 Ion-Gap Sense in Misfire Detection Knock and Engine
Control
Ion-gap sensing for engine control SAE magazine Automotive Engineering /Sept
1995
SAE paper 982476 Knock Suppression in a Turbocharged SI Engine by Using
Cooled EGR SAE paper 2001-01-0992 Employing an ionization sensor for combustion
diagnostics in a lean burn natural gas engine
Investigating GM's Compression Sense Ignition "Motor" magazine november 2004
www.asashop.org - Bosch ME engine
management system
Bentley Saab 900 "Official Service Manual" ISBN 0-8376-0313-7 6/1993 PAGE
340-2
EZK Knock Sensor Operation and Ignition Timing: ".....The timing can vary
from 5deg to 22deg BTDC in response to engine speed, engine load, or detonation.
If engine knocking occurs, the ECU determines which cylinder(s) are knocking and
retards just eh affected cylinder by 3deg....."
Spark-Advance Control by Ion-Sensing and Interpretation
www.fs.isy.liu.se
David Calabrese ME
United States
Fiat Nomenclature
Guys, I have just noticed an error in Michael Knowling's June 2000 article on
Rigoli's modified Fiat 124 Coupe. The article states:"And the later AC model -
like the one photographed here – is arguably the cleanest shape of all 124s,
thanks to its totally revised nose cone..." In fact the AC version of the 124
Coupe is the first incarnation of this model (1967-69), followed by the later BC
(1970-72) and CC versions (1973-75), each one arguably less attractive than its
predecessor, although engine size and power also increased with each successive
version.
Mark Northage
Australia
Thanks – fixed.
In-Line BOV
Thought you guys might find this interesting www.youtube.com
Company is www.steedspeed.com I also make CNC billet turbo
manifolds which you might get a kick out of. There are videos of those on
youtube too. Love your site! Lots of good grassroots stuff.
Leen Steed
Canada
Trans Coolers 1
In regards to the article Cooling the Trans
I have had a similar situation and think that I have something to add. My
modified 2002 forester had trans cooler fitted. When we fitted the modified
valve body we also braised a temp sensor into the pan of the trans. I found that
running just a trans cooler and not running through the radiator saw the hottest
temps of all. In fact I even saw the trans temp go over 110 degrees on a hot day
while stationary at traffic lights after a long highway run.
With quite a bit of fiddling I found that running the trans cooler (from a V8
VP commodore) in conjunction with the radiator gave the gest results. On most
trips and around town the trans temps would never go over about 96 degrees, even
sitting at traffic lights after a long hard run.
Having the trans cooler gave on average about a 10 degree drop in trans temps
(cruising) compared to just using the radiator but there was very little
difference between having the cooler before and after the radiator.
Hope this is of interest to you.
Brent Muldoon
Australia
Trans Coolers 2
RE: Cooling the trans - teamed with an appropriate oil filter adapter, would
those air con heat exchangers be suitable for use as engine oil coolers as
well?
Andrew Rodrigues
Australia
Not sure – pressure shouldn’t be a problem but flow might
be.
Small Turbo Engines for Economy 1
Comments:"Turbo'd for Fuel Economy". You will not be surprised to hear that
VW indeed make a smaller version of the TSI turbo engines. There are 1.4L
versions in various states of tune that easily slot into the Golf range in
Europe. One version gives a quite adequate 90kW and 200Nm (1500-3500rpm).
Apparently there is a 6% improvement in economy over the naturally aspirated
1.6L it replaces not to mention a 30% increase in maximum torque.
Richard
Australia
Small Turbo Engines for Economy 2
If you were talking about Golf's I would have thought the obvious car to
include in the comparison would be the Golf GT. But would the fact that it
required not just a turbo to get the power up to 2 litre NA levels but also a
supercharger to get the low end torque have destroyed the premise of the story,
that you can make a small engine with a turbo feel like a big engine? The
problem with that premise is the low end of the rev range where a small engine
with a big turbo on it isn't going to be responsive. If you're adding the mass
and cost and complexity of a turbo, and you can't go to a lot smaller engine,
like the 1.4 in the Golf GT, it suggests the whole idea isn't very viable. Of
course its different on a diesel because it doesn't have to spool the turbo up
when you press the accelerator.
Gordon Drennan
Australia
The 1.8 litre turbo engine has far more torque (and so power) at the bottom
end than the 2 litre naturally aspirated engine. As the above letter writer
points out, even the 1.4 litre FSI turbo develops far more torque (and so power)
at the bottom end than the 2 litre naturally aspirated engine. Who said anything
about small engines with big turbos? Not us! In fact, clearly these are small
engines with small turbos. On the 2-litre turbo there is simply no detectable
on-road turbo lag. Also, the idea that it’s different on a diesel "because the
turbo doesn’t have to spool up" is completely wrong. A diesel turbo has to spool
up just like a petrol engine turbo – the off-boost exhaust flow is not
sufficient to develop full intake manifold boost. In fact, many current
passenger car turbo diesels have more turbo lag than petrol
turbos.
Small Turbo Engines for Economy 3
Your "Turbo'd for Fuel Economy" was an interesting article, but I feel there
should be some clarification on some facts. The energy required to drive a
turbine wheel shouldn’t be referred to as "free energy". Exhaust gas speed
required to spin a turbine wheel to speeds high enough so the compressor wheel
can actually pump more air than the engine can use (generate boost pressure), is
substantially (3-4 times) higher than most normally aspirated engines exhaust
gas speed through the exhaust manifold. This can only be achieved by restricting
the flow though the turbine housing. This flow restriction then causes higher
pumping losses on the exhaust stroke. Perhaps referring to it as better
utilization of unused energy would be more appropriate?
Secondly, all the examples given were of engines with long stroke/small
bores. The same application on a bigger bore/shorter stroke engine probably
wouldn’t give the same low RPM torque results. I just feel that this should have
been mentioned as a contributory factor.
Nice article.
Howard Hartman
Australia
We take the point that pumping losses increase when the engine is
turbocharged. However, the relationship between bore/stroke and developed torque
is more problematic. An engine with a long stoke and small bore also has less
developed force on the piston...
Small Turbo Engines for Economy 4
I think you need to put the two power/torque graphs on the same axes to get a
real appreciation of the difference.
Ash
Australia
LED Lighting 1
I was very interested in your first article on LED front lighting systems for
bikes. A friend of mine has modified a couple of standard front bike lights by
inserting 5W LEDs in place of filament bulbs. I have powered these using a
bottle dynamo, but another friend of mine uses a front hub dynamo on his bike.
The LEDs seem to draw less power somehow than filament bulbs, such that a
standard 6V/3W generator can satisfactorily power 5-6W of LEDs.
I'm surprised such lights are not more widely available from cycle lighting
manufacturers. The battery-powered variety are common enough, but pricy, while
there are hardly any dynamo-powered LED front lights available. Coupled with a
hub dynamo this gives a robust, battery-free system which creates little drag,
is always ready for use and is bright enough for riding unlit roads at
night.
Ben Garside
United Kingdom
You need to be very careful with dynamo-run LED lights that the current
rating of the LED is not exceeded – current limiting is needed or high road
speeds will result in a damaged LED! But we agree that dynamo-powered LED
lighting should be more widely available.
LED Lighting 2
Having access to many excellent Mtn biking venues in the ACT i have become an
avid night rider. I was just wondering why you didn't use the more efficient
cree style LEDs for your light and if you did, do you think you could get the
thing down to a helmet wear practical size with the same light output?
There are already commercial options out there using the cree and they are
pretty good, but also pretty pricey. A good follow up project perhaps?
Justen
Australia
The headlight project has evolved over a number of years; when the project
began we don’t think Cree LEDs were available. That said, the major performance
outcome of the headlight is governed not so much by the brightness of the LED
but by the collimator and external focusing optics. For this reason we can’t see
such a headlight becoming helmet wearable in the near future.
Tuning Diesels
My brother and I are about to start a small hobby tuning business (weekends
only as we both work) for 306 Td's and Hdi's.
We recently went for
a dyno again, my car with my own remap file from scratch, made 195lbft and
119bhp.
photobucket.com
There is more to come, but not much, my AFR's were up
around 16 and then 17 ish past 3000rpm, but the non-intercooled 306Hdi means I
can't go too far as intake air temps rise with more EGT, and the associated
small increase in boosting.
An intercooler is the next job, and
then I'll be trying to find a cheap EGT measuring solution, then I can push up
the fuelling. 140bhp and 240lbft seem easily and reliably
achievable.
My brothers Td, quite amazingly, made 131bhp and
200lbft.
More interestingly, the peak torque is at 2500rpm, the peak
power at about 4000rpm, but it has over 125bhp from 3500rpm to 4800rpm, a really
wide range of power.
His AFR's were less impressive low-down,
hovering around 14.5 through 1000-2000rpm, but that helped the turbo spin up, no
boost spike (a manual boost controller may see peak torque rise and come down
the rpm range further!), and then a solid 15:1 right through with a wiff of
smoke. The Bosch boost compensator does it's job
perfectly!
photobucket.com
He has made some modifications to the Bosch pump that we
were toying with doing back five years ago on our 405 Td's, which appears to
have worked well, along with opening up the max rev potential.
He
has several spare engines, turbo's and pumps, and can swap an engine in about
half a day, so I think the current idea is to see how long it
lasts.
The current general spec is.
Stock intake but with
K&N panel filter.
GT15 turbo (late 306 Td), boosting to around 1.3-1.4
bar by 2000rpm, and holding that boost to around 4000rpm where it falls a little
(don't have the reference with me, sorry)
Decat pipe, and Powerflow stainless
steel exhaust from a 306 2.0 16v S16/GTi6.
Bosch pump fitted (was
Lucas)
The usual mods to fuelling screws, along with a few specials
inside.
I'm not sure on his economy, he doesn't check, he has a
temp sensor on the intercooler > intake manifold union (post intercooler),
and they stay down under 40degC at this time of year even under very hard use.
They only rise significantly when you stop the car running totally. I believe as
noted in a past article here, the intercooler is an interwarmer at idle, so if
you sit still but with the engine running it's better for the top-mounted
intercooler than switching off it seems.
All good fun, I will keep
you updated in the future if you wish, or maybe just send a link to our website,
where we will keep all our little tests and latest ideas and experiment write
ups!
David Crabtree
United Kingdom
Praise
simple, clear english for non rev head people, explaining what i need to
know, think about and consider before i add something to my car. just excellent.
i wanted to know about cold air intakes and, lo and behold, it's all here.
excellent site. concise and informative. well done
Sean
Australia
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