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2000 Deville
1985 Cadillac Eldorado, 22k mikes
Joined
15 Posts
Discussion Starter #1
Is Dr. Dave still on here? I have a 1985 Eldorado. It is my daily driver. It had 17k on it when I bought the car, and I've put about 5k miles on it. So far so good! Of course, it has a 4.1 馃槓馃槓馃槓. The car was so nice I bought it anyway. What with the low miles, the 4.1 is good for now, and it runs perfectly. I WILL be putting a temp gauge on it soon lol . One day I'll replace the 4100 with a b.o.p. 350 (or a 307 if I have no other option), but til it goes, I was wanting some input on increasing performance without screwing anything up. I sure appreciate any help! 馃檪馃檪馃檪
 

Super Moderator
2003 Deville Base
Joined
5,035 Posts
Welcome to the forums! you'll get plenty of comments, I'm sure, but i don't think there's much out there in the way of performance mods for a 4.1 Also, I'm going to move your post to the Eldo/Seville forum.
 

Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
87,076 Posts
One day I'll replace the 4100 with a b.o.p. 350 (or a 307 if I have no other option),
Unfortunately, that is about the only way to increase the performance of any Cadillac with a 4.1 engine.
 

2000 Deville
1985 Cadillac Eldorado, 22k mikes
Joined
15 Posts
Discussion Starter #4
Welcome to the forums! you'll get plenty of comments, I'm sure, but i don't think there's much out there in the way of performance mods for a 4.1 Also, I'm going to move your post to the Eldo/Seville forum.
THANKS!
 

Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
19,658 Posts
Welcome to the forums! you'll get plenty of comments, I'm sure, but i don't think there's much out there in the way of performance mods for a 4.1 Also, I'm going to move your post to the Eldo/Seville forum.
==========================
performance mods and 4.1 can NOT be used within the same sentence -
 

2000 Deville
1985 Cadillac Eldorado, 22k mikes
Joined
15 Posts
Discussion Starter #8
I joined this forum because of this 2005 post from a guy named "Dr Dave". Any feedback on what this guy says?

To get the best possible performance out of your
HT4100:

1. CHANGE THE CATALYTIC CONVERTER. Makes a HUGE
difference on throttle response, and also acceleration,
clogged or not. Meineke is a good place to
get it done, or any place that does it cheaper.
Magnaflow seems to be a good brand. If the
original converter is left on, it can rob the car of precious horsepower as well as throttle
response. If it has the original converter and over
80-90,000 miles, you almost certainly don't need it
tested--just replace it. Complain of low throttle
response, and difficulty attaining high speeds even
though the engine revs at high rpms. Can also cause
rough idle and difficulty starting, if the rest of the
ignition system is in decent working order.

2. Make sure your oxygen sensor is working (can make
a low growling sound when accelerating and cruising
over 30). This can affect idle, minor surging, and
cruising speeds. You can also check this with onboard
diagnostics (make sure it reads rich/lean at fast
increments.)

3. Using performance ignition components can make a
BIG difference on responsiveness, horsepower, and EASE
OF STARTING. After significant and extensive
research, I've singled out Denso Iridium spark plugs
(other Iridiums plugs may also be good), Magnecor
spark plug wires (www.magnecor.com), and Accel
performance components (ignition coil, ignition
module, distributor cap, and rotor--all available
through kragen, and sometimes autozone.) The ignition
module and coil together, both from Accel, can make
your HT4100 start in half a crank. No kidding.

4. Have a good air filter in there -- the best one
I've found for performance and good filtration is
Amsoil, available at www.amsoil.com. I wouldn't use
K&N paper filters since they can lose efficiency over
time and aren't as good for the engine.

5. Advance the timing 2 or so degrees if you want to
squeak out a few more horses. I haven't done it yet,
but it can make a pretty decent difference.

I've had this setup for two years and 15,000 miles,
and have been extremely pleased with the performance
of this HT4100. It may not necessarily be the
swiftest car on the road, but it has certainly made
this beauty an even greater pleasure to drive.

If one performs all these modifications (listed in
order of significance above), it will probably feel
like a hotrod compared to stock. Although, it may not
quite be ready for a drag race. Now mind you it'll
finish the race easy enough, just not ahead of any
other cars--unless, of course, there's another HT4100
on the track. In this setup, the components seem to
hold up very well, though if there's any ignition
symptoms in the future, check the coil--as it's
usually the first culprit to go out (coils can cause
varied ignition symptoms like rough idle, no start,
and even backfiring through the throttle body--similar
to a clogged catalytic conveter.)

Hope these comments help, and if anyone's tried these
modifications, please post and let us know your
results! My experience with my '82 Eldorado has been excellent.
As a luxury car, it's comfort and elegance is to be enjoyed
the most. But if you want a 'few' extra horses, these
mods will get them.


-Dave
 

Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
Joined
69,374 Posts
At least he's candid about noting that it's hard to get a 4100 to outrun another 4100 - or anything else, for that matter.

The catalytic converter is worthy of note. IF the '85 still had a ceramic pellet-filled converter then anything you replace it with is a big plus. Imagine filling a tin can with BBs and then trying to blow through it. The newer honeycomb core converters have literally no flow restriction when new but even slow, cool driving can partially clog a honeycomb cat.

Sure - just as with most any other engine - a few tweaks and replacements will help a little with performance. But with the 4100 cars a VW Beetle will still eat them alive.
 

2000 Deville
1985 Cadillac Eldorado, 22k mikes
Joined
15 Posts
Discussion Starter #10
Thank you for a serious answer. I'm very grateful 馃檪. You answered my main question. I'm just looking for subtle ways that might help, you know? I KNOW the 4100 is a boat anchor..... WITH an aluminum block even? WTH was GM thinking? I just can't imagine that engine ever making it into production! I've had a bunch of 307 coupes, and they were sluggish enough lol. I knew what I was in for when I bought the car, but it was just in such great shape I couldn't resist. I just wanna be able to pull out in traffic without causing an accident lol.
 

2000 Deville
1985 Cadillac Eldorado, 22k mikes
Joined
15 Posts
Discussion Starter #11
By the way, Submariner, I was looking for a way to change my info a little to add my other car, a 2000 Deville. I can't figure out how. Do you know?
 

2000 Deville
1985 Cadillac Eldorado, 22k mikes
Joined
15 Posts
Discussion Starter #12
Welcome to the forums! you'll get plenty of comments, I'm sure, but i don't think there's much out there in the way of performance mods for a 4.1 Also, I'm going to move your post to the Eldo/Seville forum.
THANK YOU! 馃檪
 

Registered
'85 Sedan de Ville, '10 CTS-V
Joined
567 Posts
Well, I never quite felt the car was sluggish. Felt a lot nimbler than my '85 300D Turbo.

Engine/Car ran like a champ:

ACCEL spiral core 10.8 mm wires
Bosch Platinum +4 plugs
Good synthetic oil 10W-30
Mobil 1 ATF in the transmission

Stopped riding like a boat when I went +1 on the wheels, I believe 15" with tire size as close as possible to keep the speedometer accurate.

Sent from my moto g(7) power using Tapatalk
 
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