[xj40] 1988 high compression Engine info

Hello,

I am looking for a used Jaguar to play with, I am mechanically
inclined and I am looking at a 1988 Vanden Plas(yes, I know its not
the best year to play with) with a high compression engine. Using
the chart I found at

http://www.motorcarsltd.com/information/jaguar-vin.htm

I noticed 2 different engine options. Can someone please give me
more info on the High compression engine (USA)

1988 Vanden Plas High Compression Engine SAJKV1640JC506664
1988 Vanden Plas Low Compression Engine SAJKV1540JC506664

1988 XJ6 High Compression Engine SAJHV1640JC506664
1988 XJ6 Low Compression Engine SAJHV1540JC506664

Thanks
Chuck Neste–
Chuck Neste
Atlanta, GA, United States
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You won’t find one if you are in the US, all catalyzed engines were low
compression, the high compression engines are European only and only those
counties like the UK where catastrophic converters were not needed.
By definition the VDP is a US market Daimler, and so will be catalized and
therefore have a low compression engine. I believe the compression is
altered by the use of different pistons

Stewart----- Original Message -----
From: “Chuck Neste” chuck_neste@yahoo.com
To: xj40@jag-lovers.org
Sent: Thursday, July 24, 2003 4:33 AM
Subject: [xj40] 1988 high compression Engine info

Hello,

I am looking for a used Jaguar to play with, I am mechanically
inclined and I am looking at a 1988 Vanden Plas(yes, I know its not
the best year to play with) with a high compression engine. Using
the chart I found at

http://www.motorcarsltd.com/information/jaguar-vin.htm

I noticed 2 different engine options. Can someone please give me
more info on the High compression engine (USA)

1988 Vanden Plas High Compression Engine SAJKV1640JC506664
1988 Vanden Plas Low Compression Engine SAJKV1540JC506664

1988 XJ6 High Compression Engine SAJHV1640JC506664
1988 XJ6 Low Compression Engine SAJHV1540JC506664

Thanks
Chuck Neste


Chuck Neste
Atlanta, GA, United States
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In reply to a message from Chuck Neste sent Thu 24 Jul 2003:

Thanks for the reply. I did find a VIN that appears to have the
High Compression motor in Texas. I am assuming this has been
imported over to the US. Unfortunately, It probably wont pass
Georgia State emmisions.

Thanks
Chuck

http://www.autotrader.com/findacar/vdetail.jtmpl?
car_id=131358942&dealer_id=629335&car_year=1988&make=JAG&distance=an
y&max_price=2000&model=&advcd_on=n&end_year=2004&min_price=2&first_r
ecord=26&certified=n&address=30144&search_type=used&advanced=n&start
_year=1983&=&color=&cardist=699

VIN SAJHV164SJC550879

Garland, TX 75041–
Chuck Neste
Atlanta, GA, United States
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Stewart,

This is most assuredly not true. In the US, only the earliest 1988
XJ40s have low-compression engines. Most 1988s and all 1989 to 1994
XJ40s have high-compression engines, and require premium fuel.

It would probably be a good idea to research US-spec cars a bit more
before supplying information about them.

-David
1994 XJ40 4.0

You won’t find one if you are in the US, all catalyzed engines were
low>compression, the high compression engines are European only and only
those
counties like the UK where catastrophic converters were not needed.
By definition the VDP is a US market Daimler, and so will be catalized
and
therefore have a low compression engine. I believe the compression is
altered by the use of different pistons


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In reply to a message from Chuck Neste sent Thu 24 Jul 2003:

After a conversation with greg from COVENTRY WEST, INC, he informed
me that the engines was changed in the 1988 production year . 1988
Production year had 2 engines that was used. Initally the low
compression engine was used and then changed over to the high
compression engine. The high compression was used from 1988 and on
for performance issues.
Thanks
Chuck–
Chuck Neste
Atlanta, GA, United States
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My car has the high compression engine and it passed the CT emissions
test before I moved here

Jay XJ6 VDP Majestic

David Berman wrote:

Stewart,

This is most assuredly not true. In the US, only the earliest 1988
XJ40s have low-compression engines. Most 1988s and all 1989 to 1994
XJ40s have high-compression engines, and require premium fuel.

It would probably be a good idea to research US-spec cars a bit more
before supplying information about them.

-David
1994 XJ40 4.0

You won’t find one if you are in the US, all catalyzed engines were
low
compression, the high compression engines are European only and only
those
counties like the UK where catastrophic converters were not needed.
By definition the VDP is a US market Daimler, and so will be catalized
and
therefore have a low compression engine. I believe the compression is
altered by the use of different pistons


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In reply to a message from Jay sent Fri 25 Jul 2003:

Did anyone ever answer Dave’s original question?

what are the compression ratios on the low vs. high comp
engines? is the difference due to different piston size, stroke
length, etc.?

as to the low compression version, did it not require premium
octane fuel?–
&:-)) Paul '88 XJ6 VDP 127k (and '90 XJS coupe on way
Garland, Texas, United States
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Paul,

My 85 Series III ran on regular. All my other Series III’s required 94
octane. My 90 Majestic requires 92 Octane.

Here are the compression pressures from my Shop Manual for XJ40’s 86-94,
2.9, 3.2, 3.6 and 4.0

2.9L Europe 210 to 230 lbf/in2
2.9L Rest of World 200- 220 lbf/in2
3.6L Europe and North America 160 - 170 lbf/in2
3/6L Rest of World 150 - 160 lbf/in2
3.2 and 4.0 160-170 lbf/in2

Compression Ratios
3.2L 9.75:1
4.0 9.5:1
2.9L Europe 12.6:1
2.9L Rest of World 11.17:1
3.6L Europe and N. America 9.6:1
3.6L Rest of World 8.2:1

My Drivers Manual for my 1990 Majestic says it has a 9.5:1 compression
ratio which agrees with my shop manual.

Does this answer the question? It looks like the limp wristed 2.9 had
the highest compression ratio while the 4.0 and 3.6 ratios are so close
that an engine with oversized pistons and liners could have more or less
depending on what you had. I think the Word High Compression is a
rather meaningless term when you have the actual numbers quote above.
Right?

Since Jaguar offered Grade A and Grade B Piston (smallest 3.6L Grade A
Piston was 90.960 largest grade be with 0.20 oversize (available) added
was 91.007) the displacement could vary considerably but I would think
the compression ratio would be the same.

If you wanted to spice up a 4.0 - 3.58 automatic differential ratio, you
could buy a 3.2 Automatic Differential - 4.09 ratio which would give you
a lot more off the line speed but knock down the top speed from 147 or
so. 3.6 automatic differential ratios were 3.54:1 But hey who wants to
drag LOL.

The lenght of the piston rods center to center on the 3.2 were 175.285
and the 4.0 was 164.42

The bore and stroke is
3.2 91x83
4.0 91x102
2.9 91x74.8
3.6 91x92

This should be enough technical specs right?

Now, my question is has anyone ever rebuilt a 4.0 with over size pistons
and liners and changed to the 4.0 rear end?

AttyDallas wrote:

In reply to a message from Jay sent Fri 25 Jul 2003:

Did anyone ever answer Dave’s original question?

what are the compression ratios on the low vs. high comp
engines? is the difference due to different piston size, stroke
length, etc.?

as to the low compression version, did it not require premium
octane fuel?


&:-)) Paul '88 XJ6 VDP 127k (and '90 XJS coupe on way
Garland, Texas, United States
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Jay wrote:

Now, my question is has anyone ever rebuilt a 4.0 with over size pistons
and liners and changed to the 4.0 rear end?

Check out Mark Twomey’s “Growler”:
http://www.prestige-spares.com.au/growler1.html

Oversized pistons and X300 XJR rear end!

Regards,
Peter Graham

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Paul,

As best I can tell, the difference between the LC and HC engines is all in
the pistons, as that’s the only place in the microfiche where there’s a
reference to a part as “High Compression” or “Standard Compression.”

I have been unable to come up with compression numbers for either variant.
It looks like Jag never published that info. I did find “compression
pressure” in the specs section of the dealer manual set, but don’t know if
these figures refer to the HC or LC engine. The manual shows 160-170 psi for
“European” and “Federal” engines and 156-160 psi for “Rest of World”
engines.

Best regards,

Gregory Wells 800-331-2193 x103
Coventry West, Inc. - Atlanta, GA www.coventrywest.com
New, Rebuilt, and Used Jaguar & Land-Rover Parts

AttyDallas

Did anyone ever answer Dave’s original question?

what are the compression ratios on the low vs. high comp
engines? is the difference due to different piston size, stroke
length, etc.?

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In reply to a message from Gregory Wells sent Mon 28 Jul 2003:

Compression ratio for the European (high compression) AJ6 3.6L is
9.6:1, for all of the 4.0L engines is 9.5:1 and for all of the 3.2L
is 9.75:1. I don’t know the low compression figure for the 3.6L.–
Dave Lokensgard, '90 VDP Majestic
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In reply to a message from Gregory Wells sent Mon 28 Jul 2003:

Although some sources I have indicate the 4.0L AJ6 has a 10:1 CR.
Maybe it varied a bit through the years…–
Dave Lokensgard, '90 VDP Majestic
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Dave

My owners manual and the owners shop manual clearly state the 90 4.0L
engine with automatic has 9.5:1 compression and I posted all the data on
this a few days ago 2.9, 3.2, 3.6 and 4.0 in Europe, NA and the rest of
the world

Jay 90 Majestic

Dave Lokensgard wrote:

In reply to a message from Gregory Wells sent Mon 28 Jul 2003:

Although some sources I have indicate the 4.0L AJ6 has a 10:1 CR.
Maybe it varied a bit through the years…

Dave Lokensgard, '90 VDP Majestic
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Jay wrote:

My owners manual and the owners shop manual clearly state the 90 4.0L
engine with automatic has 9.5:1 compression and I posted all the data on
this a few days ago 2.9, 3.2, 3.6 and 4.0 in Europe, NA and the rest of
the world

Thanks a lot, Jay. However, the factory brochure for the 1994 XJ6 lists the
compression ratio as 10:1, which was the basis for my statment. Check out
the Jag-Lovers “brochures” pages if you like. And also thanks for the
number on the low-compression 3.6, 8.2:1, that sounds right.

http://www.jag-lovers.org/brochures

Dave Lokensgard
'90 Vanden Plas Majestic (DAVZCAT)
'55 XK140 OTS
Poway, California

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Dave,

Remember that a 1994 XJ6 brochure if from the UK would likely refer to
an X300, not an XJ40. My 1994 XJ40 4.0 has 9.5:1 compression ratio. I
am under the impression that the 10:1 ratio applies only to the AJ16
engine because a knock sensor is required to prevent detonation with
that ratio.

-David
1994 XJ40 4.0__________________________________
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Dave

I am quoting from a Jaguar Owners Shop Manual not a brochure. I do not
doubt the Sales Brochure states what you said nor do I mean to offend
you, but…if push comes to shove, I would believe a shop manual that
is so detailed it lists all internal moving parts that wear with size,
tolerances, two types of Pistons, Grade A & Grade B as well as the two
over sizes available for pistons and liners (+0.010 and +0.020) over a
Sales Brochure. Brochures are often written and sometimes printed
before final design is completely settled or cars produced.

My NZ Published Jaguar Shop Manual (Owners Edition) is for the Jaguar
and Daimler XJ6 Saloons from 1986 to 1994. I would say the Brochure is
mistaken and I am sure the factory would agree if asked.

The XJ6 2.9L Compression for Europe 12.6:1 Rest of World 11.17:1
(Apparently no 2.9L’s sold in NA)
XJ6 3.6L Compression Europe & NA 9.6:1 Rest of World 8.2:1

The XJ6 4.9L has a uniform 9.5:1 compression ratio on all models which
is confirmed by my Factory Drivers’ Manual that also states 9.5:1
Compression Ratio.

The 3.6 and 4.0 have the same length connecting rod 166.42 mm and bore
91 mm. Difference in displacement is in the stroke 92 mm for the 3.6
and 102 mm for the 4.0

The XJ6 3.2L I have no idea where this was sold had a compression ratio
of 9.75:1
There is no listing for a compression ratio of 10.0:1 anywhere in the
Jaguar Owners Ed. Shop Manual or my Factory Drivers Manual.

Comparison of bore x stroke and compression volumes in the same manual
agree with the compression ratios listed above. None equal 10.1:1 when
you do the math. By the way the crankshaft is balanced to 10 gm/cm and
the valve.

Some other useful facts for the guy that had the rear camber question.
It should be between -0.5 degrees and -1.5 degrees

Since the company that printed it MAP Books is no longer in business
they probably wont mind if I scanned the mechanical specifications
section.

Jay 90 Majestic

Lokensgard wrote:

Jay wrote:

My owners manual and the owners shop manual clearly state the 90 4.0L
engine with automatic has 9.5:1 compression and I posted all the data on
this a few days ago 2.9, 3.2, 3.6 and 4.0 in Europe, NA and the rest of
the world

Thanks a lot, Jay. However, the factory brochure for the 1994 XJ6 lists the
compression ratio as 10:1, which was the basis for my statment. Check out
the Jag-Lovers “brochures” pages if you like. And also thanks for the
number on the low-compression 3.6, 8.2:1, that sounds right.

http://www.jag-lovers.org/brochures

Dave Lokensgard
'90 Vanden Plas Majestic (DAVZCAT)
'55 XK140 OTS
Poway, California

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