Jaguar E-Type 4.2 Dyno Run
Discussion
Fantastic morning at Sigma Engineering in Dorset, and Peter Lander really knows his onions.
1st power run aborted as mixture was everywhere, carbs "bouncing" and manifold glowing red hot
Timing adjusted & optimised, new heavier springs fitted in carbs, carbs balanced, fuel pressure checked & mixture sorted
Power run here:
http://www.youtube.com/watch?v=FY4xXbcoQ-Q&fea...
1st power run aborted as mixture was everywhere, carbs "bouncing" and manifold glowing red hot
Timing adjusted & optimised, new heavier springs fitted in carbs, carbs balanced, fuel pressure checked & mixture sorted
Power run here:
http://www.youtube.com/watch?v=FY4xXbcoQ-Q&fea...
rolymo said:
Enquiry to Sprocketman 01 :- Your comment is not very explanitary, you made a statement but we did not learn anything to our advantage. Please give us the benefit of your knowledge :- What is good ? What is bad ? What should we beware of ? when useing RR. Thanks!! 
Well the first thing you should do is put pieces of rag into the inlet manifold ports, because if you drop a nut down there, you'll be a sorry boy when you fire the engine up.J
CaptainSensib1e said:
For those unable to access videos (at work), what did it make? Also be good to know what the quoted output fom Jag was when they came out!
As many marques, the originally quoted figures were very very optimistic. I'm reliably informed that a standard / "good" 4.2 will deliver around 230/240bhp.My engine spec is lightened / balanced bottom end, lightweight flywheel, ported big valve head, special cams, tubular exhaust manifold & system, matched ram pipes to SU carbs & produced 279bhp which is slightly down on what was quoted when the engine was built 25 years ago - allbeit the cam timing has been set to standard to aid road usability
Candellara said:
CaptainSensib1e said:
For those unable to access videos (at work), what did it make? Also be good to know what the quoted output fom Jag was when they came out!
As many marques, the originally quoted figures were very very optimistic. I'm reliably informed that a standard / "good" 4.2 will deliver around 230/240bhp.My engine spec is lightened / balanced bottom end, lightweight flywheel, ported big valve head, special cams, tubular exhaust manifold & system, matched ram pipes to SU carbs & produced 279bhp which is slightly down on what was quoted when the engine was built 25 years ago - allbeit the cam timing has been set to standard to aid road usability
Remember that modern cars are measured DIN, classics will be measured gross so you can take 10% off immediately.
As for how much a bog-standard 4.2 engine makes, I doubt it's as much as 230bhp. The 'evidence' (as I see it!) follows...
The acceleration figures and top speed of an E-type or XJ6 suggest that they have less then my 200bhp BMW 328i. Despite being lighter the E-type can't beat that car to 60 or to 100mph. In fact, type the numbers into a power to weight calculator (1250kg, 7 sec. to 60), and you'll find an E-type must have around 160bhp to record the performance figures it does. Do the same thing with a manual Jaguar XJ6 S1 (1600kg, 8.7sec to 60) and you get the same-ish value. Lets be kind and give a margin for poor tyres and gearboxes (perhaps the ratios are terrible) but I still think it's somewhat less then 200bhp..probably more like 180bhp.
From the other side, the last version of the XK engine (in fuel injected, big-valve SIII spec) was rated at 205bhp. Surely the carb version produced less?
I am interested in this and would love to see a dyno plot of a standard engine, or the one in the videos above.
varsas said:
Before I start, I do think the XK engine is truly wonderful. I'm the very proud owner of a 4.2 SI XJ6.
Remember that modern cars are measured DIN, classics will be measured gross so you can take 10% off immediately.
As for how much a bog-standard 4.2 engine makes, I doubt it's as much as 230bhp. The 'evidence' (as I see it!) follows...
The acceleration figures and top speed of an E-type or XJ6 suggest that they have less then my 200bhp BMW 328i. Despite being lighter the E-type can't beat that car to 60 or to 100mph. In fact, type the numbers into a power to weight calculator (1250kg, 7 sec. to 60), and you'll find an E-type must have around 160bhp to record the performance figures it does. Do the same thing with a manual Jaguar XJ6 S1 (1600kg, 8.7sec to 60) and you get the same-ish value. Lets be kind and give a margin for poor tyres and gearboxes (perhaps the ratios are terrible) but I still think it's somewhat less then 200bhp..probably more like 180bhp.
From the other side, the last version of the XK engine (in fuel injected, big-valve SIII spec) was rated at 205bhp. Surely the carb version produced less?
I am interested in this and would love to see a dyno plot of a standard engine, or the one in the videos above.
I can't help you with standard figures and i'd need to scan my sheet, but if it helps:Remember that modern cars are measured DIN, classics will be measured gross so you can take 10% off immediately.
As for how much a bog-standard 4.2 engine makes, I doubt it's as much as 230bhp. The 'evidence' (as I see it!) follows...
The acceleration figures and top speed of an E-type or XJ6 suggest that they have less then my 200bhp BMW 328i. Despite being lighter the E-type can't beat that car to 60 or to 100mph. In fact, type the numbers into a power to weight calculator (1250kg, 7 sec. to 60), and you'll find an E-type must have around 160bhp to record the performance figures it does. Do the same thing with a manual Jaguar XJ6 S1 (1600kg, 8.7sec to 60) and you get the same-ish value. Lets be kind and give a margin for poor tyres and gearboxes (perhaps the ratios are terrible) but I still think it's somewhat less then 200bhp..probably more like 180bhp.
From the other side, the last version of the XK engine (in fuel injected, big-valve SIII spec) was rated at 205bhp. Surely the carb version produced less?
I am interested in this and would love to see a dyno plot of a standard engine, or the one in the videos above.
Corrected power 279.9bhp
Wheel power 232.7bhp
Max power at 5710rpm
Torque 281.0 lbft
Max torque at 4335rpm
Max attained rpm 5990rpm
Ambient temp 23.5C
Intake temp 24.4C
FWIW, alot of the heavily modified E-Types (on SU's) are running at about 260 to 280 (modified heads / cams / exhausts) To get near 300 you'd require triple webbers
Edited by Candellara on Monday 12th August 18:55
Candellara said:
varsas said:
Before I start, I do think the XK engine is truly wonderful. I'm the very proud owner of a 4.2 SI XJ6.
Remember that modern cars are measured DIN, classics will be measured gross so you can take 10% off immediately.
As for how much a bog-standard 4.2 engine makes, I doubt it's as much as 230bhp. The 'evidence' (as I see it!) follows...
The acceleration figures and top speed of an E-type or XJ6 suggest that they have less then my 200bhp BMW 328i. Despite being lighter the E-type can't beat that car to 60 or to 100mph. In fact, type the numbers into a power to weight calculator (1250kg, 7 sec. to 60), and you'll find an E-type must have around 160bhp to record the performance figures it does. Do the same thing with a manual Jaguar XJ6 S1 (1600kg, 8.7sec to 60) and you get the same-ish value. Lets be kind and give a margin for poor tyres and gearboxes (perhaps the ratios are terrible) but I still think it's somewhat less then 200bhp..probably more like 180bhp.
From the other side, the last version of the XK engine (in fuel injected, big-valve SIII spec) was rated at 205bhp. Surely the carb version produced less?
I am interested in this and would love to see a dyno plot of a standard engine, or the one in the videos above.
I can't help you with standard figures and i'd need to scan my sheet, but if it helps:Remember that modern cars are measured DIN, classics will be measured gross so you can take 10% off immediately.
As for how much a bog-standard 4.2 engine makes, I doubt it's as much as 230bhp. The 'evidence' (as I see it!) follows...
The acceleration figures and top speed of an E-type or XJ6 suggest that they have less then my 200bhp BMW 328i. Despite being lighter the E-type can't beat that car to 60 or to 100mph. In fact, type the numbers into a power to weight calculator (1250kg, 7 sec. to 60), and you'll find an E-type must have around 160bhp to record the performance figures it does. Do the same thing with a manual Jaguar XJ6 S1 (1600kg, 8.7sec to 60) and you get the same-ish value. Lets be kind and give a margin for poor tyres and gearboxes (perhaps the ratios are terrible) but I still think it's somewhat less then 200bhp..probably more like 180bhp.
From the other side, the last version of the XK engine (in fuel injected, big-valve SIII spec) was rated at 205bhp. Surely the carb version produced less?
I am interested in this and would love to see a dyno plot of a standard engine, or the one in the videos above.
Corrected power 279.9bhp
Wheel power 232.7bhp
Max power at 5710rpm
Torque 281.0 lbft
Max torque at 4335rpm
Max attained rpm 5990rpm
Ambient temp 23.5C
Intake temp 24.4C
FWIW, alot of the heavily modified E-Types (on SU's) are running at about 260 to 280 (modified heads / cams / exhausts) To get near 300 you'd require triple webbers
Edited by Candellara on Monday 12th August 18:55
varsas said:
Thanks. Looks very strong. The first thing that caught my eye was the revs, I think my road car is red-lined at 5k rpm!
Yep, something that needs addressing. At just below 6000rpm on the dyno the engine was struggling IMO (valve bounce?) and yet the rev limiter is set at 7000rpm!In the real world though the engine only gets revved to about 5k as i'm fairly sympathetic with it (given she's 43!)
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