i can add some interesting info about this subject, fuel vaporization, Padre brought up Smoky Yunick of Daytona FL. , he did a lot of R&D for the big three USA car companies.

i was around at that time ,and drove some of his experimental cars , the primary purpose was better fuel consumption.

he called the engines ADIABATIC engines, well one idea he used was to bring the fuel to a boiling point, using exhaust heat(not a new idea just much better design than heating carb base), and completley vaporized fuel before it ever reached the chambers(NO large fuel droplets or puddling,a big problem on cold start engines), and when accelerating even when hot!

also a very unusual powerful ignition system along with an advance curve, he never said what tho?

to make power he added a thing he called a HOMOGENIZER (custom turbocharger).
the Atomized fuel was fed into the mouth of the turbo compressor,spinning high revs made the fuel much faster to Vaporize,(seeing as that is what we a trying to do).

well as i remember, one of the cars was a full size early 80s, Oldsmobile sedan that he hired me and some crew to do a 200mile road trip, and carefully observed fuel tank filling ,managed 34 miles per gallon (US gallon). whats that in Imperial around 37/38 mpg? 4200 lbs of car.

but his best was a compact 4 cylinder Mopar early 80s got over 50mpg, on a lot of testing gasoline/petrol 91octane US .

what was impressive was they had respectable performance,relative to most vehicles of the day.

all and all he was quite an ingeniuos engineer and has many patents to his name!

 

Make a manometer with a bit of clear tube (long enough to reach to the front of the car through the window) and a bit of plywood or MDF, or you can purchase a digital one, my digital one is calibrated and fullscale is 20"H2O.

You need to find a place that has high pressure. Place the tube on the front of the car where you think you will place the intakes, make sure the tube is at right angles to the direction of flow. You can test a number of different places.

You will need to do a number of runs in opposite directions with the tube in each place to take into account any wind.

Interestingly the official fuel consumption figures for the XJS are as follows in L/100km's in Australian trim.

1989 V12 5.3L, I can confirm this is about what I get.
Urban 21
Open Road 12
Combined 15.4

1995 V12 6.0L
Urban 18
Open Road 11.5
Combined 13.9

 

Gentlemen, I took a different approach IMHO to the under bonnet air/venting. Assumption #1..air inside engine bay is under pressure from fan and forward motion of machine with all lower valence and sealed radiator surround.
#2...cold air induction enhanced with tubes and modified intake horns "ala Bernie Emden", removal of front seal strip to bonnet and bonnet liner to encourage additional air flow into and back to the firewall.
#3 removal of hood latch ala "the Grant of Frances"..installation of gas struts Honda hatch back...1/4-3/8" longer allowing deployment of hood at arrested stance.(very dramatic when you pull in and stop at the local ????)
#4 installation of reversed/upside down vent louvres at back 1/3 of the bonnet...idea was that air pressure would be able to vent vertically as well as back and down around the Trans./ground sytem as originally designed. The AC bracket at the front was skeletonized along with the throttle pedastle.
#5 as you guys know I am a big proponent of the Lutz Cooling System Mod. Stage1 for street machines along with the t-stat seal inside the castings.
Have yet to do an in depth empirical study, but hope it is making a difference at idle (can feel heat exiting vents at still)
Will try to add photos of the venting and engine bay for your perusal, best, JW

 

Mine has been consistently similar.

Urban, 18-20
Highway, last big trip (20000kms) 11.2

In L/100kms as well.

5.3ltr Lucas, large throttle discs, no AAV, no balance pipe, cold air intakes only, Efans, Non Resistor spark plugs, no PCV system, 10W40 Syn oil, Freeflow exhaust (slightly noisier than standard), no radiator seals, no air pump, no cats (never fitted), 16CU ECU, XJ40 TPS, timing set by "drive timing", so no idea what degrees its at, 98 RON fuel only.

 

Aha, some where in my gadget collecting days, I got a manometer.
I think it was at a garage sale. A gal selling her departed mate's gear.
A heavy duty engine mechanic. Used in engine intake balance.


My son made use of these in tow ways:


1. Balancing the carbs of his very hot Suzuki 1200.


2. His self built flow bench for carbs, manifolds and cylinder heads.


Wonder what he will do with mine when I pass??? Not too long, I suspect.


Carl

 

hey guy try not to rush things.

 

gotta love old fashioned HOT ROD tuning!!

i tune the same way, and 50 degrees BTDC at 3000rpm, idle about 28 at 1000rpm!

no ping, 93 octane USA juice! seems preHE dont ping easily!

great response, blows the tires off when below 15/20mph in 1st, shifts to 2nd instantly!

i have very little use of factory tuning specs, never have on any of my cars, i'm on a different agenda!

 

The "open road" figure is almost exactly what I get on a 1994 6.0, USA spec. on a highway drive. Surprisingly, the car seems very sensitive to wind, a headwind will increase the fuel usage a fair bit.

 

that usually indicates poor drag coieficent increase,, or engine dont make enough torque for the rpm range,, so you push the pedal down more and waste fuel!

 

The following thread spans more than 10 years ... can't figure things out
when dates are not iso format:

Heat Extractor Hoods - Corner-Carvers Forums

Notice towards the end of the thread there are lots of hoods
fitted with the extractor insert from Mustang GT500's.

$80 from the dealer ... what can you get from a Jaguar dealer for $80?

 

A cup of coffee...................

 

Grant, can you explain the balance pipe delete? And where does your ecu reference vacuum?

 

yes why the balance pipe delete??

 

Delete, as in removed from the car.

Vac sourcing is via 2 spigots fitted for the PCV system (also removed), and 2 equal length hoses to the rear of the fuel rail, where a Brass T connects them both to the ECU vac hose.

I have a specific write up on this, but it is 11.7mb and way too big for here, sooooooo, if ya want it, PM me your direct email address, and I will oblige.

 

It got in the way, looked ugly, tooo many vac leak poossibilties, AAV continually getting hissy.

Then the good old Aussie "outside the square thinking" kicked in, and there are better ways to balance the 2 engines vac , and since I am OLD, I looked at carby V12, no such pipe, so I simply took it off.

The booster 2 hoses balance, the 2 ECU vac hoses also assist, then my total **** setting of the throttle discs, rods etc, means the 2 discs are SPOT ON EVEN when coming off idle, the critical area, so I had nothing to lose.

 

.

fair enough Grant, if you say so!

but why would Jag have put the balance tube in 1st place, on FI V12s, wonder what there thinking was?

got it the AAV , for FI engines , left side only, gotta have a fast idle when cold, so balance tube balances vacuum for both sides!

 

Grant,, how do you fast idle when cold???

i have no fast idle,so i hold the gas pedal at around 1100/1200 rpm, til engine gets some temp in it, after warm up, idles around 850/900 rpm.

looking to put an AIR solenoid in the elec. circuit connect it to a pin on ECU, that opens when adjustable temp has been reached!

but would like to have one adjusts air volume also!

got any ideas for cold fast idle, or for A/C control?

ron

 

Your ECU should support IAC, check with the manufacturer if it can support PMW IAC, then use any Ford IAC valve. You would need to fabricate a mount.

Or simply change the AAV for a manually operated butterfly and have an old fashion choke

 

I had 2 of the Extra Air Solenoids from the RH air cleaner backing plate, part of the 15 minute timer rubbish.

Sooooo, I used the 2 hollow studs from the front of the inlet manifold, that were the vac source for the FPR's, and fitted them to the rear plates of each manifold. I tucked the 2 solenoids under each inlet manifold, out of sight, and one end had a hose that went TO those hollow studs, the intake end (other end) went via a hose to the air cleaner backing spigot the Over-run Valve hose once went to, SIMPLE.

They are switched by ME inside the car, and raise the cold idle by about 200RPM, which is more than enough.

This is all in the paper that is toooo big for here.

Her XJ12 PreHE had an Audi solenoid, and it worked sweet.

Another had a BMW valve of some sort, that was a challenge, but its still working today.

Any solenoid that is CLOSED when NO volts are present will do. The sizing of the orifice will need sorting, that is why I used the 2, as their orifice is smallish. The Audi and BMW were larger bore, so 1 per engine.

 

Saw an idea on another website dedicated to V12; they used an adjustable Nippon denso part from a Toyota for replacement extra air valve, perhaps you could adapt the ideaJaguar V12 Supplementary Air Valve