[xj-s] Manual Transmission options for V12 For a Track Day/race car

XJ-S
21

MGuar wrote:

Nice to know the Getrag isn’t all that stout so I won’t waste
effort trying to find one of those…

Aren’t there a couple of different Getrags? IIRC, there’s a common
one that’s capable enough for a 6-cyl or stock V12, but there’s
another that’s tough enough for the modern supercharged engines.

However the T5 is used in so
many cars/trucks that I can get them in simple trades… (going price
seems to be a set of early flat heads)

The T5 NWC is also only marginal. The Borg-Warner you’d want is the
modern 6-speed used in Vipers, I think it’s called the T56? It
reportedly has carbon synchros. It has two overdrive ratios, but
that doesn’t mean anything, either way you just pick the final drive
ratio that makes all six ratios do what you want them to.

– Kirbert

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22

In reply to a message from Kirbert sent Thu 6 Jan 2011:

For our applications only a V8 T5 WC is acceptable.
I use a Viper T56 behind my 7.5L V12 beacause it’s the only box
that can handle the 500+ lb/ft. torque, but I would never use it in
a race car, it’s too heavy, nearly twice the weight of the T5 and
it rquires major surgery to the floor pan to get in the XJ-S.–
The original message included these comments:

The T5 NWC is also only marginal. The Borg-Warner you’d want is the
modern 6-speed used in Vipers, I think it’s called the T56? It
reportedly has carbon synchros. It has two overdrive ratios, but
that doesn’t mean anything, either way you just pick the final drive

–
850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
HEIDELBERG HEIGHTS, Australia
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23

In reply to a message from A.J. Simpson sent Wed 5 Jan 2011:

the difference is the ratios, but with 3.7/3.8 1st gear ratios they
are not ‘‘race car’’ material.
New you can find them for $6500+ or $2200 S/H.
Some one claims they are good for 1500HP but if you google them you
will find a lot of broken ones that didn’t have even 500HP applied.–
The original message included these comments:

The V160, V161 are much beefier boxes and are supposed to be much better boxes all around. I don’t know the difference between the V160 & V161, though.

–
850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
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24

In reply to a message from MGuar sent Wed 5 Jan 2011:

parts are no problem for the Jag box and they can handle all the
power a V12 can give them.
In the UK you can even buy new EJ gearsets if you need.–
The original message included these comments:

The Jaguar 4 speed parts can be purchased from XK’s unlimited… I

–
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25

In reply to a message from lockheed sent Wed 5 Jan 2011:

Haynes Manual, 1972-1980 (pre HE) page 20 says the engine makes
284 HP@5750RPM & 294 ft.pounds of torque at 4500RPM
Who cares… Cleaned up* and tuned up** it’s close enough to the
about 300 hp I spoke about that few would quibble…
*smog equipment amd cats/muffler removed.
**Fuel Mixture richened to 11.5 to 1
Please remember the HE was an attempt to get fuel mileage not
increase horsepower. Due to the restrictive nature of HE heads
power potential is reduced in spite of an 11:1 compression ratio
Further compounded by going to a 15.5:1 fuel air ratio.
Before you get upset about potential smog realize this is a
trackday/race car that combined with my other race cars is unlikely
to see 1000 miles a year… in fact a few hundred is a more
reasonable estimation…
In addition this car will be a test bed for things like 100%
ethanol Since it’s generally agreed that the additional air
molecules in Ethanol increases power output by approximately 20%
that should quickly approach the limits of a T5 transmission…
(that’s before I add the twin turbos)… (which I only count on
increasing the horsepower by 150)–
MGuar
Wayzata Minnesota, United States
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26

In reply to a message from Kirbert sent Thu 6 Jan 2011:

Kirbet;
Well made point… IN additon I expect to further reduce the strain
on the gear box by getting the weight down to the absolute minimum.
Hopefully around 2500 pounds…
On the other hand I will be adding to the load factor by the use
of 10 inch wide slicks…
I haven’t wrapped up in my mind weather to chance using a T5 or
go straight to the racing gear box … (and forget driving it on the
street completely)
That’s the reason for th whole inquiry see if there is a gearbox
out there I’ve overlooked…–
The original message included these comments:

More to the point, that wasn’t your point. If a particular
transmission is good for 300 hp, then it’s good for 265 hp or
whatever, I wouldn’t even worry about it for 320 hp. Like someone
said, it’s torque that breaks a transmission anyway – although I
might argue it’s actually vehicle weight. Either way, the point is

–
MGuar
Wayzata Minnesota, United States
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27

In reply to a message from MGuar sent Thu 6 Jan 2011:

‘‘Since it’s generally agreed that the additional air molecules in
Ethanol increases power output by approximately 20%’’

Really, perhaps you have confused ethanol with methanol. But, you
make repeated references to ethanol, not methanol. How can ethanol
provide provide more energy when tests indicate ethanol/gasoline
blends perform poorly compared to straight gasoline in terms of
both mileage and performance?

http://www.edmunds.com/fuel-economy/e85-vs-gasoline-comparison-
test.html

Do your own search on Google for ‘‘ethanol vs gasoline’’.

More power from Methanol? You bet, a drag racer favorite - not
ethanol.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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28

In reply to a message from MGuar sent Thu 6 Jan 2011:

‘‘Haynes Manual, 1972-1980 (pre HE) page 20 says the engine makes
284 HP at 5750RPM & 294 ft.pounds of torque at 4500RPM.’’

The Haynes manual neglected to tell you that was for the Euro spec
pre HE engine. The US spec (with emissions controls) pre HE V12
was rated at 180KW (242 HP). That’s why there was the phrase for
the US spec HE:

‘‘From July 1981, XJ-S received the new High-Efficiency engine for
much better economy; as a by-product, power was increased to 196 kW
(263 hp) in North America’’–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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29

In reply to a message from lockheed sent Thu 6 Jan 2011:

Methanol is made basically from coal… ethanol is made from mainly
corn. They both have free oxygen molecues available. Once you
understand that all engines are simply air pumps Getting free
oxygen should explain why there is a potential 20% improvement
alcohol over pump grade gasolene…
There is a slight increase in power with methanol over ethanol…
However the Indy cars are all burning ethanol… As were the
Corvettes in this years endurance series.
As for Gasolene/alcohol mixtures well a little bit of knowledge
is a dangerous thing. Before you make any statement about
performance etc… you need to know what the base stock of gasolene
is. Because the octane of ethanol alcohol is 114 it’s relatively
easy to start with a gasolene base stock down around 75 and still
wind up over 87 octane… (depending on the percentage of ethanol
used… ) In addition there are hundreds of possible combinations
of gasolene base stock to achieve a given octane rating… what is
the composition of the lite ends etc…

Well to avoid turning this into a chemistry lesson which is what
is really required to understand why a little bit of knowledge is a
bad thing.
In addition you need to understand what we’re talking about
burning the fuel… Low compression like early V12’s have (7.8-1)
won’t make much of an improvement, however when we’re talking
about High comprtession or turbo charging etc. the game changes.
Here’s the reason I will use ethanol over gasolene… 100% alcohol
has 114 octane and If I go to the plant and denature it on site
(to avoid paying the alcohol tax) plus use my own drums I can buy
it around a dollar a gallon (last time I bought any) Methanol last
time I looked into it was up near $7.00 a gallon…
That’s not such a great deal as it seems on the surface… First
you need twice as much alcohol as gasolene) so it effectively
costs $2.00 a gallon… and since there is no distribution,
transportation costs, or retail costs added to the price we’re
likely talking about a cost around $3.00 a gallon if all those were
added in…
OK few people know someone at a plant who is willing to work with
them to sell fuel direct.(too much hassle and some serious
paperwork is required). So few can drive up and buy it that
way…–
MGuar
Wayzata Minnesota, United States
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30

In reply to a message from MGuar sent Thu 6 Jan 2011:

There is no need to talk down to members of this forum. Don’t
presume that you have some secret, clairvoyant, omniscient, and
exclusive knowledge of the function and theory of the operation of
internal combustion engine unknown to others. Anyone that has been
paying attention the past few years knows where ethanol comes from,
maybe not so many about where methanol comes from - probably
because methanol has nothing to do with the everyday fuels
available to most, and most of us use.

Your interest and thrust seem to be in the higher octane values of
ethanol and methanol, not of the specific heat values of each vs
gasoline. That’s OK for those interested in moderate to highly
modified engines with higher compression ratios, high levels of
turbo or supercharging and wishing to use ethanol and methanol in
their purer forms, but that is not the world that most of us live
or operate in. The fact remains that the ethanol/gasoline mixtures
available to the public from the pump are a step down in
performance and fuel mileage as pointed out in the links I
provided - specific heat values and octane of each
notwithstanding. And, they are used in our modern engines which
have higher compression ratios (higher than the early V12 7.8-1
that you referenced) and OEM turbocharged and supercharged engines
as well. The bottom line is that ethanol (despite your claim of
higher energy levels, oxygen availability, etc.) in mixtures
commonly avialable to the public at the pump is a step down in
performance and fuel mileage.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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31

In reply to a message from lockheed sent Fri 7 Jan 2011:

You’re missing the point… The title said track day/race car…
Nothing about street cars. Further your points about HE engines
isn’t relavent either… Racers won’t use them!
Ethanol has 114 octane which is usefull in a racing/track day
applications…
I’ve seen people pay as much as $14.00 a gallon for racing fuel.
That makes racing insanely expensive. $1.00 a gallon or there
abouts for ethanol starts to look extremely attractive…
Considering how easy it is to modify the Fuel injection system on
the earlier cars, it’s a simple alternative. The earlier cars also
use a 7.8 compression which tolerates a decent amount of boost
pressure…–
MGuar
Wayzata Minnesota, United States
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32

In reply to a message from MGuar sent Fri 7 Jan 2011:

It is easy to get pulled into this ‘which box is better’ debate.

But the real issue, I find, is getting the ratios right. This is
not easy to do with the XJS, with its 2.88 rear gear. The T56 is
pretty much out of contention for use with the 2.88 rear gear, way
too long legged. It is useable with a 3.54, or better still, 3.73+

A really good combo for this car is a 3.54 rear and a close ratio
TKO or similarly ratio’d richmond box (esp. if 6 speed). That is,
a first gear total ratio of somewhere around 10.5 to maybe 12 or
so. I run a ‘wide ratio’ TKO and a 2.88, and it’s much too tall
for my tastes (total ratio of around 9.4)…although it beats the
daylights out of the TH400. I will be putting in a 3.31 this
spring.

If I were making a road race car, I’d be sorely tempted to use a
3.54 to 3.73 rear and a close ratio richmond 6, again, to get the
ratios to come out where I wanted.

The only box of which I am aware that enables better tuning of the
ratios with respect to the 2.88 rear, is the Geforce 5 speed. That
box can be dialed in directly, it appears.

More HP/torque from the motor, and you can get away with a smaller
numerical final drive ratio.

-M–
Mike, 1990 5.3 XJS Conv., 5-speed, SE-ECU, TT Extractors
Lakewood, OH, United States
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33

In reply to a message from MGuar sent Thu 6 Jan 2011:

Yada Yada Yada - for those interested in some factual stuff:

Energy content (High and low heating value)
A plastic container used widely for storing gasoline.Gasoline
contains about 35 MJ/L (9.7 kW�h/L, 132 MJ/US gal, 36.6 kWh/US gal)
(higher heating value) or 13 kWh/kg. This is an average; gasoline
blends differ, and therefore actual energy content varies from
season to season and from batch to batch, by up to 4% more or less
than the average, according to the US EPA. On average, about 19.5
US gallons (16.2 imp gal; 74 L) of gasoline are available from a 42-
US-gallon (35 imp gal; 160 L) barrel of crude oil (about 46% by
volume), varying due to quality of crude and grade of gasoline. The
remaining residue comes off as products ranging from tar to naptha.
[9]

Volumetric and mass energy density of some fuels compared with
gasoline (in the rows with gross and net, they are from [10]):

Fuel type[clarification needed] Gross MJ/L MJ/kg Gross BTU/gal
(imp) Gross BTU/gal
(U.S.) Net BTU/gal (U.S.) RON
Conventional gasoline 34.8 44.4[11] 150,100 125,000 115,400
Autogas (LPG) (60% Propane + 40% Butane)[citation needed] 26.8
46 108
Ethanol 21.2[11] 26.8[11] 101,600 84,600 75,700 113[12]
Methanol 17.9 19.9[11] 77,600 64,600 56,600 123
Butanol[2] 29.2 36.6 91-99[clarification needed]
Gasohol 31.2 145,200 120,900 112,400 93/94[clarification needed]
Diesel(*) 38.6 45.4 166,600 138,700 128,700 25
Biodiesel 33.3-35.7 [13][clarification needed] 126,200 117,100
Avgas (high octane gasoline) 33.5 46.8 144,400 120,200 112,000
Jet fuel (kerosene based) 35.1 43.8 151,242 125,935
Jet fuel (naphtha) 127,500 118,700
Liquefied natural gas 25.3 ~55 109,000 90,800
Liquefied petroleum gas 91,300 83,500
Hydrogen 10.1 (at 20 kelvins) 142 130[14]

(*) Diesel fuel is not used in a gasoline engine, so its low octane
rating is not an issue; the relevant metric for diesel engines is
the cetane number–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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34

In reply to a message from MGuar sent Thu 6 Jan 2011:

OOoops, sorry, previous post accidental - hit wrong key.

Anyway, (for anyone interested) there is a good treatise on
various automotive fuels. Go to about the middle part of the
article and there is a good table of the heat values and other
information for various fuels.

http://en.wikipedia.org/wiki/Gasoline--
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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35

In reply to a message from lockheed sent Sat 8 Jan 2011:

OK again we’re talking about racing so that’s what’s relevent here…
Indy Cars and The Factory Corvettes run in the LeMans
endurance series run here in America use ethanol. I believe that
one of the sportscars clubs is planning on allowing ethanol in the
near future. Bonneville allows alcohol and fuel blends in various
classes.
Sprint cars and drag racers use methanol for the same reason.
Nitromethane has even more free oxygen molecules. Thus
blending fuels is not allowed in some classes while is allowed in
other classes…
What was not given in those charts is cost data… Since that is
extremely variable I would be foolish to try to set up charts
here… In the end racers will use whatever they can legally that
makes the most power. (and a tiny percentage will cheat)
In my case since the use of alcohol is not forbidden on most track
day events I will use whatever gives me the best bang for my
dollar…–
MGuar
Wayzata Minnesota, United States
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36

MGuar wrote:

Indy Cars and The Factory Corvettes run in the LeMans
endurance series run here in America use ethanol. I believe that one
of the sportscars clubs is planning on allowing ethanol in the near
future. Bonneville allows alcohol and fuel blends in various classes.

Sprint cars and drag racers use methanol for the same reason.

Actually, the reasons are different. Indy used methanol for years
for performance reasons, but switched to ethanol a few years back for
political reasons – ethanol is “green”.

– Kirbert

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37

In reply to a message from Kirbert sent Sun 9 Jan 2011:

I’m sure a little money changed hands when the track switched from
methanol to ethanol…
I doubt politics had anything to do with it…
Racing pretty well shrugs off attacks on it buy those of us
concerned about the enviornment… (Yeh, I’m one of those)
As for performance, Corvettes choose ethanol when racing in the
American LeMans series because ethanol gave them enough of an
advantage to overcome some pretty serious attacks by Aston Martin,
Ferrarri, and Porsche.
It’s sort of lame but they used GM’s Flex Fuel as an arguement to
have it allowed… (did money or perks change hands? we’ll likely
never know because few care.–
MGuar
Wayzata Minnesota, United States
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38

MGuar wrote:

I’m sure a little money changed hands when the track switched from
methanol to ethanol…

Exactly. By switching to ethanol, they were able to reap some bucks
for promoting a green fuel that’s available to the public.

As for performance, Corvettes choose ethanol when racing in the
American LeMans series because ethanol gave them enough of an
advantage to overcome some pretty serious attacks by Aston Martin,
Ferrarri, and Porsche.

Well, having the ALMS officials rule that the Aston Martin had to
carry around a coupla hundred pounds of extra weight didn’t hurt.

It’s sort of lame but they used GM’s Flex Fuel as an arguement to
have it allowed… (did money or perks change hands? we’ll likely
never know because few care.

Can you get a Corvette in a Flex Fuel model?

– Kirbert

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39

In reply to a message from Kirbert sent Sun 9 Jan 2011:

Kirbert;
Hotrod did a series of dyno races a while back and in some they
used ethanol fuel… Some of the compression ratios were fantastic!
aproaching 15 to one when pure ethanol was used… With compression
ratios that high the power numbers were fantastic…
The overly simple comments about blends are telling half truths…
Many blends are made from base stocks which would be too low of
octane to be used for motor fuel but by adding the 114 octane of
ethanol they blend up to the 87 octane rating.
So use of ethanol isn’t as simple as the anti ethanol people would
have you believe…
Next currantly no engines are designed to take full advantage of
114 octane. Untill you see compression ratios of 13-14 to 1 or
boost pressures of three atmospheres or higher with 9-1
compression you won’t be gaining full benefit either.
The flaw isn’t the additional power in Ethanol… It’s the lousy
fuel mileage… In general it takes twice as much alcohol as
gasolene to drive. Make the engines more geared towards ethanol and
that additional fuel requirement can be lowered…
That’s in part why Corvette raced with ethanol… GM is slow in
gaining acceptance to the idea of flex fuel… Only recently have I
seen some Ford engines with it…
Once honest flex fuel becomes wildly accepted nation wide then the
potential for real gains exists… The new ZR1 is supposed to have
the ability to accept E85 (85% ethanol) except it’s use would put
the Corvette in the fuel hog penalty tax area… Something Corporate
GM can’t allow…
As Far as ethanol being a green fuel… I’m sorry that’s like
saying clean coal! True there are some benefits to the atmosphere
in the final stage. However production does tend to use dieselfuel
rather than Biodiesel… PLus we are gaining only modestly over
crude based stocks…
However the stretch that Ethanol does provide allows lower base
stocks to be used and thus more gallons per barrel results…
Estimates vary and seem based more on which side of the issue you
are on but if we take the worst numbers and add them to the
increase in output per barrel we’re gaining 20%
The pro ethanol boys claim 30% instead of just 5%. That may be
true here in the corn belt but I doubt is valid nation
wide…–
MGuar
Wayzata Minnesota, United States
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40

In reply to a message from mike90 sent Sat 8 Jan 2011:

Mike
You make really valid points, all of them…
Except for a race car…
On the race track 3.54 final is too high (depending on the
diameter of the tires used and the track raced at)
Ratios for Elkart Lake for example a 4 mile track with three
really long straights in a light, powerful car 3.78 is about
right. 4.10 might be better on days with low air density. It’s
true your top speed would be limited by say 10 MPH But since that
is only near the very end of a long straight the additional
acceration gained by the 4.10 over the 3.78 would prevent passing…
IF by chance the 3.78 should squeek ahead the 4.10 would take it
right back accerating out of the next corner…
Acceration wiuns races not top speed…
That’s why racers often use rather modest camshafts… races are
won and lost in acceration and to trade some of that for extra
horsepower at peak RPM is foolish!
Oh one transmission nobodies mentioned yet… The Corvette C4’s
4+3 I had one of those in my 86 Corvette and they aren’t all that
bad… I tended yto use it like most did and a 4 speed with electric
overdrive…
The advantage of that over every other transmission listed is how
cheap they are… The close ratio Richmond is $3500 compared to the
$200 I’ve seen 4+3’s sell for…–
The original message included these comments:

not easy to do with the XJS, with its 2.88 rear gear. The T56 is
pretty much out of contention for use with the 2.88 rear gear, way
too long legged. It is useable with a 3.54, or better still, 3.73+
A really good combo for this car is a 3.54 rear and a close ratio
TKO or similarly ratio’d richmond box (esp. if 6 speed). That is,
a first gear total ratio of somewhere around 10.5 to maybe 12 or
so. I run a ‘wide ratio’ TKO and a 2.88, and it’s much too tall
for my tastes (total ratio of around 9.4)…although it beats the
If I were making a road race car, I’d be sorely tempted to use a
3.54 to 3.73 rear and a close ratio richmond 6, again, to get the

–
MGuar
Wayzata Minnesota, United States
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