Rescue's Official Build Thread - 88 XJS V12 Oct 12 2019
#1061
Got the rhs tb on and the rear parts connected to the intake manifold
I almost forgot about the tb return springs til I saw one on the cowling lol. Put one on and was fine but other one seemed streched. Probably from when I lifted the whole assembly off and forgot about it.
So ordered 2 replacement ones from sng as well as some rubber elbows i needed.
Still looking for an answer to my question I posted.
Can I just replace this pipe connection with a hose? Circled in black.
I almost forgot about the tb return springs til I saw one on the cowling lol. Put one on and was fine but other one seemed streched. Probably from when I lifted the whole assembly off and forgot about it.
So ordered 2 replacement ones from sng as well as some rubber elbows i needed.
Still looking for an answer to my question I posted.
Can I just replace this pipe connection with a hose? Circled in black.
#1062
#1063
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#1065
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#1066
#1067
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#1068
#1069
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#1070
These three options are not the whole story. The XJS was originally launched with the 5.3 litre fuel injection engine. It had the so-called "flat-head" cylinder head. This same engine was in the E Type and early models of the saloon, but with carburettors. The XJS was the first jaguar to have a fuel injected V12. It was powerful but used very large amounts of fuel, especially in traffic.
In about 1982/83 this same basic engine was produced with a new cylinder head designed by a Swiss engine combustion specialist called Michael May and called the HE cylinder head by Jaguar, HE meaning High Efficiency. This cylinder head gave a bit more power, but very much better part-throttle fuel economy. This is what is referred to as the HE engine.
Slightly confusingly, this 1982/3 relaunched version of the XJS was called the XJS HE. When launched, the XJS with the HE engine was fitted with catalytic converters for certain markets, but not for others. The USA cars for example had catalysts, but UK cars did not. So some HE cars had catalytic converters and some did not.
From later on, about 1989 or 1990 I think, all HE engined XJSs regardless of markets had catalysts.
Sometime in the late 1980s Jaguar stopped using the HE description on the V12 XJS and just called it the XJS V12. But the engine in the car remained the same HE version.
From about 1992 or maybe a year later (do not know the actual date), the 5.3 litre HE engine was expanded in capacity to 6.0 litres, but the cylinder head design remained the same apart from some mods to give the desired combustion ratio. So 6 litre engined XJSs have an HE-headed engine but just a bit larger in capacity.
In about 1982/83 this same basic engine was produced with a new cylinder head designed by a Swiss engine combustion specialist called Michael May and called the HE cylinder head by Jaguar, HE meaning High Efficiency. This cylinder head gave a bit more power, but very much better part-throttle fuel economy. This is what is referred to as the HE engine.
Slightly confusingly, this 1982/3 relaunched version of the XJS was called the XJS HE. When launched, the XJS with the HE engine was fitted with catalytic converters for certain markets, but not for others. The USA cars for example had catalysts, but UK cars did not. So some HE cars had catalytic converters and some did not.
From later on, about 1989 or 1990 I think, all HE engined XJSs regardless of markets had catalysts.
Sometime in the late 1980s Jaguar stopped using the HE description on the V12 XJS and just called it the XJS V12. But the engine in the car remained the same HE version.
From about 1992 or maybe a year later (do not know the actual date), the 5.3 litre HE engine was expanded in capacity to 6.0 litres, but the cylinder head design remained the same apart from some mods to give the desired combustion ratio. So 6 litre engined XJSs have an HE-headed engine but just a bit larger in capacity.
The main reason for the HE head was to conform to upcoming California smog regulations about to be introduced. Since more than 50% of Jaguar sales are to America loss of the US market would have been the death blow to the then struggling Jaguar. ( by the early 1980’s Jaguar was losing over £50 million pounds a year.
Higher compression naturally increases fuel mileage while retarded timing hurts it. But much of the fuel mileage gains was due to other improvements such has taller gear ratio. (From 3.07-2.88) introduction of the GM turbo 400 in 1978, revised fuel injection from the Bosch system to the Lucas system.
Race cars always used the earlier pre HE heads due to better flow. The HE heads limit flow to the point that going beyond 450 hp is extremely difficult. While the Pre HE heads have made as much as 894 hp.
Last edited by Mguar; 10-04-2021 at 11:13 AM.
#1071
minor corrections . The HE was introduced in 1981 also the US horsepower was the same as the earlier pre HE. The ignition timing went from 38 degree down to 17 degrees to keep from preignition or detonation on gasoline available at the pump. With racing gas 110 octane time can be advanced to 38 degrees and an increase in power is the result.
The main reason for the HE head was to conform to upcoming California smog regulations about to be introduced. Since more than 50% of Jaguar sales are to America loss of the US market would have been the death blow to the then struggling Jaguar. ( by the early 1980’s Jaguar was losing over £50 million pounds a year.
Higher compression naturally increases fuel mileage while retarded timing hurts it. But much of the fuel mileage gains was due to other improvements such has taller gear ratio. (From 3.07-2.88) introduction of the GM turbo 400 in 1978, revised fuel injection from the Bosch system to the Lucas system.
Race cars always used the earlier pre HE heads due to better flow. The HE heads limit flow to the point that going beyond 450 hp is extremely difficult. While the Pre HE heads have made as much as 894 hp.
The main reason for the HE head was to conform to upcoming California smog regulations about to be introduced. Since more than 50% of Jaguar sales are to America loss of the US market would have been the death blow to the then struggling Jaguar. ( by the early 1980’s Jaguar was losing over £50 million pounds a year.
Higher compression naturally increases fuel mileage while retarded timing hurts it. But much of the fuel mileage gains was due to other improvements such has taller gear ratio. (From 3.07-2.88) introduction of the GM turbo 400 in 1978, revised fuel injection from the Bosch system to the Lucas system.
Race cars always used the earlier pre HE heads due to better flow. The HE heads limit flow to the point that going beyond 450 hp is extremely difficult. While the Pre HE heads have made as much as 894 hp.
#1072
#1073
115 to 120 alt a GREAT idea, I went through alternators all the time until I upgraded to one, everything worked better with it, instruments, voltage levels, everything. The 75 amp OEM one is just not powerful enough.
#1074
It's Thanksgiving weekend coming up in Canada so I hope I can get some more work done
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#1075
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#1076
#1077
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#1078
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#1079
#1080