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Amici,
I don't know how many of you are running rev limiters. The text below
details some of my recent (and first) experience with a limiter, and the
manufacturer's response.
I have been kicking myself for screwing up six or seven race weekends while
I fooled around with this problem, but it all goes back to lack of
knowledge of the product on my part. That, and not really thinking out the
problem very well. I had convinced myself that it couldn't be the rev
limiter because it didn't act like I thought a rev limiter would.
My question to the group is, how much cushion if any, do you set into the
limit? If your target shift point is 6,000rpm, where do you set the
limiter?
----------
From: Adrian Goodsell <autocar@dircon.co.uk>
To: beeline@iline.com
Subject: Re: Luminition Ignition/Rev Limiter
Date: Wednesday, April 28, 1999 11:50 AM
Mr Beasley The Lumenition Rev Limiter is a full cut device designed to cut
all sparks above the set rev limit. To that end it will prevent an
acceleration over revving but will not prevent a mechanical driven over rev
such as selecting 2nd instead of 4th or an inertial effect. The symptoms
you describe may be an effect of the coil waveform on the device. It is
possible that the particular characteristics of coil, leads, spark gap and
combustion requirements are causing the coil negative waveform to feedback
extra signals into the rev limiter that trick it into seeing a higher
engine speed than real. I have seen this on some occasions but it does not
appear to be predictable. It may be that something you have changed
recently has affected this if the system was operating correctly when first
fitted. Possibly altering spark gaps or a different coil may have an
effect. When seen it may only happen whilst the engine is under load and
the rev limiter reads the rpm correctly if there is no load on the engine.
The other possibility is that the rev limiter is operating at its set rpm
but the coil is still producing a spark (even with its voltage limited)
enough to fire the combustion. This can occur with high energy coils or
with the engine at light loads. Even limited a standard coil may provide a
3 to 4 Kv spark which can be just enough to fire a light mixture. A
rolling road with ignition scope facilities may be able to further trace
exactly what is happening. When the rev limiter cuts in the ignition trace
will change from the normal pattern to a square low voltage pattern. The
coil negative pattern may show signs of multi sparking or high voltage
noise. If the problem persists we do have a Micro Dynamics rev limiter
which offers similar performance but has a slightly different input filter
which may operate more successfully with your particular setup. Regards
Customer Support
-----Original Message-----
From: Roger Beasley <beeline@iline.com <mailto:beeline@iline.com>>
To: autocar@denaploy.co.uk <mailto:autocar@denaploy.co.uk>
<autocar@denaploy.co.uk <mailto:autocar@denaploy.co.uk>>
Date: Monday, April 19, 1999 8:30 PM
Subject: Luminition Ignition/Rev Limiter
Dear Sirs:
Sometime last year, I purchased a Luminition amplifier kit and rev limiter
from your American distributor, XK's Unlimited. The units were installed
on my vintage Triumph TR4 racecar.
Initially, all was well with the unit but after some subsequent work due to
cracked intake manifold, etc, the rev limiter must have inadvertently been
reset to a lower limit. For some time and a number of race meetings, the
car would pull strongly to 5100 rpm whereupon, it began to burbble or
"knit" as my tuner put it. At that point, I chose to shift. But if
pressed, I was able to pull through on up near the desired redline of 6000.
The problem was not so pronounced in first and second gear as in third and
fourth.
Because of the ability to pull on up past the initial point where engine
miss began, I assumed it was a carbueration problem. However, this past
weekend, I made an appointment with my engine builder for a test day at a
nearby track. After much experimentation with mixture and no improvement,
he finally decided to eliminate the rev limiter from the equation. The
limiter proved to be the problem as without it, the engine would pull
strongly up the range to the desired limit. Reattachment of the limiter
brought back the problem. We further experimented with increasing the
adjustment of the limiter until it only began to affect the engine at
approximately 6400 rpm allowing for a cushion on the normal 6000 working
limit.
My question is this, how exactly does the unit work to limit revs? Is it
an extremely soft cut which is designed to allow an additional amount of
revs after the initial onset? The main use I have for a limiter is to
prevent zinging the engine in case of a missed shift. And, I don't wish to
come up against the limiter on each shift. Am I putting your unit to its
proper application?
Roger Beasley
Cape Coral, Fl
1962 TR4 Racecar
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<html><head></head><BODY bgcolor=3D"#FFFFFF"><p><font size=3D2 =
color=3D"#000000" face=3D"Arial">Amici,<br><br>I don't know how many of =
you are running rev limiters. The text below details some of my =
recent (and first) experience with a limiter, and the manufacturer's =
response. <br><br>I have been kicking myself for screwing up six =
or seven race weekends while I fooled around with this problem, but it =
all goes back to lack of knowledge of the product on my part. =
That, and not really thinking out the problem very well. I =
had convinced myself that it couldn't be the rev limiter because it =
didn't act like <u>I thought </u>a rev limiter would.<br><br>My question =
to the group is, how much cushion if any, do you set into the limit? =
If your target shift point is 6,000rpm, where do you set the =
limiter?<br><br>----------<br>From: Adrian Goodsell <<font =
color=3D"#0000FF"><u>autocar@dircon.co.uk</u><font =
color=3D"#000000">><br>To: <font =
color=3D"#0000FF"><u>beeline@iline.com</u><font =
color=3D"#000000"><br>Subject: Re: Luminition Ignition/Rev =
Limiter<br>Date: Wednesday, April 28, 1999 11:50 AM<br><br>Mr =
Beasley<font size=3D3> <font size=3D2>The Lumenition Rev Limiter =
is a full cut device designed to cut all sparks above the set rev limit. =
To that end it will prevent an acceleration over revving but will =
not prevent a mechanical driven over rev such as selecting 2nd instead =
of 4th or an inertial effect.<font size=3D3> <font size=3D2>The =
symptoms you describe may be an effect of the coil waveform on the =
device. It is possible that the particular characteristics of =
coil, leads, spark gap and combustion requirements are causing the coil =
negative waveform to feedback extra signals into the rev limiter that =
trick it into seeing a higher engine speed than real. I have seen =
this on some occasions but it does not appear to be predictable. =
It may be that something you have changed recently has affected =
this if the system was operating correctly when first fitted. =
Possibly altering spark gaps or a different coil may have an =
effect. When seen it may only happen whilst the engine is under =
load and the rev limiter reads the rpm correctly if there is no load on =
the engine.<font size=3D3> <font size=3D2>The other possibility is =
that the rev limiter is operating at its set rpm but the coil is still =
producing a spark (even with its voltage limited) enough to fire the =
combustion. This can occur with high energy coils or with the =
engine at light loads. Even limited a standard coil may provide a =
3 to 4 Kv spark which can be just enough to fire a light mixture.<font =
size=3D3> <font size=3D2>A rolling road with ignition scope =
facilities may be able to further trace exactly what is happening. =
When the rev limiter cuts in the ignition trace will change from =
the normal pattern to a square low voltage pattern. The coil =
negative pattern may show signs of multi sparking or high voltage =
noise.<font size=3D3> <font size=3D2>If the problem persists we do =
have a Micro Dynamics rev limiter which offers similar performance but =
has a slightly different input filter which may operate more =
successfully with your particular setup.<font size=3D3> <font =
size=3D2>Regards<font size=3D3> <font size=3D2>Customer =
Support<font size=3D3> </p>
<p><font size=3D2><b>-----Original Message-----</b><br><b>From:</b> =
Roger Beasley <<font color=3D"#0000FF"><u>beeline@iline.com</u><font =
color=3D"#000000"> <<font =
color=3D"#0000FF"><u>mailto:beeline@iline.com</u><font =
color=3D"#000000">>><br><b>To: </b><font =
color=3D"#0000FF"><u>autocar@denaploy.co.uk</u><font color=3D"#000000"> =
<<font color=3D"#0000FF"><u>mailto:autocar@denaploy.co.uk</u><font =
color=3D"#000000">> <<font =
color=3D"#0000FF"><u>autocar@denaploy.co.uk</u><font color=3D"#000000"> =
<<font color=3D"#0000FF"><u>mailto:autocar@denaploy.co.uk</u><font =
color=3D"#000000">>><br><b>Date:</b> Monday, April 19, 1999 8:30 =
PM<br><b>Subject: </b>Luminition Ignition/Rev Limiter<br><br>Dear =
Sirs:<br><br>Sometime last year, I purchased a Luminition amplifier kit =
and rev limiter from your American distributor, XK's Unlimited. =
The units were installed on my vintage Triumph TR4 racecar. =
<br><br>Initially, all was well with the unit but after some =
subsequent work due to cracked intake manifold, etc, the rev limiter =
must have inadvertently been reset to a lower limit. For some time =
and a number of race meetings, the car would pull strongly to 5100 rpm =
whereupon, it began to burbble or "knit" as my tuner put it. =
At that point, I chose to shift. But if pressed, I was able =
to pull through on up near the desired redline of 6000. The =
problem was not so pronounced in first and second gear as in third and =
fourth. <br><br>Because of the ability to pull on up past the =
initial point where engine miss began, I assumed it was a carbueration =
problem. However, this past weekend, I made an appointment with my =
engine builder for a test day at a nearby track. After much =
experimentation with mixture and no improvement, he finally decided to =
eliminate the rev limiter from the equation. The limiter proved to =
be the problem as without it, the engine would pull strongly up the =
range to the desired limit. Reattachment of the limiter brought =
back the problem. We further experimented with increasing the =
adjustment of the limiter until it only began to affect the engine at =
approximately 6400 rpm allowing for a cushion on the normal 6000 working =
limit.<br><br>My question is this, how exactly does the unit work to =
limit revs? Is it an extremely soft cut which is designed to allow =
an additional amount of revs after the initial onset? The main use =
I have for a limiter is to prevent zinging the engine in case of a =
missed shift. And, I don't wish to come up against the limiter on =
each shift. Am I putting your unit to its proper =
application?<br><br>Roger Beasley<br>Cape Coral, Fl<br>1962 TR4 =
Racecar</p>
<p><br></p>
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