S3 V12 weber six pack carburettor set-up--any views?

[JJC]

My money on the Daytona. LOL I still have my 73 E, but sold my Daytona long ago (like an idiot). Two different animals. No matter what you do, not going to beat the Daytona. And after all, makes no matter. Fun exercise, however. Mount the camera in the Jag, so you can shoot the Ferrari as it drives off in to the distance. Have fun !

John

[lowact]

Yep. A stock 6.0L V12 in an E would have max power-to-weight ratio of 146 W/kg. Woolfgang may not have this much, due to the relatively small capacity of his induction system, i.e. if 4 (41 mm dia) stromberg carbs =100%, std Jag efi with twin (64 mm dia) throttle bodies would =120% and six double-barrel (28 mm dia) Webers would =140%.
Compared to this a Daytona has max power-to-weight of 162 W/kg so yes, in a fair fight the 4.4L Daytona (V12 with 6 Weber carbs) should win.
All performance parameters from www.automobile-catalog.com.

[jagwit]

Compared to this a Daytona has max power-to-weight of 162 W/kg so yes, in a fair fight the 4.4L Daytona (V12 with 6 Weber carbs) should win.

How do think the Daytona would do against a Jag XKR 4.0 Supercharged?

The reason I'm asking is that my ex-71 OTS (11:1 CR pistons, std HE heads, lightweight flywheel, standard HE EFI hardware with my Megasquirt ECU / dual EDIS-6 ignition) ran head to head with my friend's XKR - neither could outrun the other.

tn2_DSCF1158.jpg (214.12 KiB) Viewed 4486 times

[Woolfi]

The reason I' would like to do the compare with the Daytona is, that I have done such a accelaration-race againt a Maserati Quattroporto. year 2007 , 4 dorrs, 390 DIN hp. From 40 - 100 mph neither could outrun the other. Head on head we climbt up the speed range.
I was thinking, that the Daytone has a wight of 1680 kg. This is wrong. If the Daytona has a wight of 1500 kg or less, he will accelerate much qicker than my EV12 with 6,0 L motor.
I calculated the power for my motor with roundabout 310 DIN, because of the compare with the Maserati (more than 1800 kg and 390 DIN hp).
Hello Philip you are wasting ponies ! The 2 butterflies of your injektion have 64 mm, but the pipe to the airfilter has much less. Bigger pipe, slightly more power.
Also this construction is sucking hot air. Hot air is less dense, than cold air. If the airfilter would breath cold air from beside or from the front of the watercooler, the motor would have few ponies more.
I think that a injected EV12 motor has roundabout 20 - 30 hp more than the same 5,3l motor with 4 Stromberg carbs. But with a hot-air intake you will loose 30 - 40% of this advantage.
Regards Wolfgang Gatza

[Woolfi]

My money also on the Daytona.
Fun exercise, however. I will mount a camera in the Jag, so I can shoot the Ferrari as it drives off in to the distance and other viewer can have fun in youtube.
My cousin is driving a 700 hp Porsche 935 on oldtimer-races and I hope he will like the idea to fight agaginst the RFE (red Ferrari eater).
Showing a shiny oldtimer on a oldtimer meeting in the sun is so boring.
That is muuuuuuuch more exciting !

Regards Wolfgang Gatza

[Woolfi]

The Strombies are too small, the original V12-injection is because of bigger butterflies better ? Maybe, but see:
http://www.widman.biz/English/Calculators/CFM.html
If I calculate my EV12 6,0l motor with an volumetric efficiency of 0,8, I need 509 CFM at 6000 rpm.
One Stromberg has roundabout 200 CFM, four of them have 800 CFM. Therefore the 4 Stromberg carbs are big enough to feed the V12 6,0 L with air.
Is something wrong with my calculation ?
If yes, I will immediately buy 4 SU 2" and "destroy" the Daytona.
Regards Wolfgang Gatza

[lowact]

How do think the Daytona would do against a Jag XKR 4.0 Supercharged?

Stock 4.0L XKR 370 hp, 1600 kg = 172 W/kg should see off the Daytona (Wt. = 1600kg). But should also have seen off yr car, say equivalent to 1990 XJS-S1 non-catalyst engine = 217 kW in 1515 kg E = 143 W/kg. Also, this was at high altitude? Usual assumption is that forced-induction (FI) can be adjusted to compensate for altitude while normally-aspirated (NA) cannot … Maybe (???) if roots-type FI was NOT adjusted the altitude hit on it might instead be worse, … I can imagine this could (?) be the case depending on the design …

Hot air is less dense, than cold air. If the airfilter would breath cold air from beside or from the front of the watercooler, the motor would have few ponies more.
I think that a injected EV12 motor has roundabout 20 - 30 hp more than the same 5,3l motor with 4 Stromberg carbs. But with a hot-air intake you will loose 30 - 40% of this advantage.

I prefer Roger Bywater’s explanation:
“The rule about air temperature is simple, cool for power (maximum charge density), hot for economy (minimum charge density to reduce losses due to throttling). In this respect the standard arrangement is much better than many people think. Sure, the under-bonnet air temperature at idle can easily get up around 70 C but the faster the car goes the lower the air temperature falls - simply because the radiator is passing its heat to a much larger quantity of air per second - so at 80 m.p.h. the engine is breathing air at around 45 C. That's still a bit higher than the ideal but not nearly so bad as many people think. Obviously the arrangement helps to maximise economy in moderate speed urban cruise without compromising top end power too much.”

One Stromberg has roundabout 200 CFM, four of them have 800 CFM. Therefore the 4 Stromberg carbs are big enough to feed the V12 6,0 L with air.
Is something wrong with my calculation ?

This article would suggest maybe yes …
http://www.hotrod.com/articles/how-big- ... -you-need/
I use choke size only as indication of relative induction system capacity, which is only really determined by bench test? With Jaguar V12 there is maybe (?) benefit in having small capacity induction on large 6.0L engine as u have done, air velocities will be higher so mid range torque should be especially good? If this is at the expense of top end power, so what, mid-range is always useful while top end is only for drag racing, and even then, if the race is restricted to top gear only, you would always win?

I really enjoyed that youtube vid of the dude on the moped, with style like that he deserved to survive …

[Woolfi]

1. 800 cfm seems to be a lot of carb for a EV12 motor with 6,0l. If the calculation say 509 CFM are okay, 800 are far above this.
2. If the temparature of the air into the airfilter is 45 C, there will be a noticable difference in power to the same motor, if he is breathing air of 25 C.
3. My car has a cold air inlet plus heated air at idle and part throttle. Like the original system of the EV12 airfilter-box.
The motor with carbs has a water heating of the induction system. I think the motor with injection does not need this. Therefore the temperature of the air at the valves of the carbed motor will be relativly higher compared with the temperature of the mixture at the valve of the car with injection.
Immanuel Kant said: "If the discussion will not find to an end, only a real life test can help." Thats why I like to compare cars on the street.
I dont think, that the 6,0 L motor in my car has only 217 hp. If the original E-type had 268 HP Din, the same motor with 14% more displacement can have 268 x 1,14 = 305 hp. I have "openend" my complete exhaust system and also (58 mm instead if 32 mm) the pipe to the airfilter. The result was, that the mixture was muuuuch leaner than before. This indicates that these two simple "operations" helped to improve the air-flow. This would add few / some hp more to 305 hp.
I have an article from a jaguar-magazine, in which the two operations Jaguar has done with the car have been described, for the press test drives in 1971 in Italy, to improve the cars top power. The car was roundabout 7mph qicker with the two changes. 7 mph would be roundabout 25 - 30 hp ! This would be a lot for such two simple improvements.
I think Jaguar has also changed the needles. Otherwise the drop of power would be dramatic, plus danger of holes in the piston because of overheating at hight speed on the italian autostada.
Regards Wolfgang Gatza

[lowact]

I know nothing except what I read on www.automobile-catalog.com
217 kW = 291 hp is the max pwr attributed to efi 5.3L V12 by this site. The 6.0L in factory trim has a lot more, Here are two examples, also the Daytona:
https://1drv.ms/u/s!AiSPBKa26IcchKZ8toDUSiI9yxuDfg
Torque curves, highest is the XJRS, lowest is the Daytona.
As far as I know the only Jaguar difference is that the series 2 XJR-S has Zytec ecu with sequential efi. This engine in an etype would have power-to-weight = 163 W/kg which is same as the Daytona. In this case my money would be on the jag, having to maintain >500 rpm more than the jag in the (slightly) heavier Daytona (just to keep up) might be difficult, even for a racing driver …
Wolfgang maybe u could dyno test yr car, see how the torque curves compare with the above? If not enough, better than SU's might be to convert to XJR-S S2 spec, the ultimate factory 6.0L v12, bolt-on upgrade, wouldn't have to invent yr own maps and u already have Getrag g/box so drivetrain should cope?
http://ccspares.org/product/zytec-kit/

[jagwit]

Also, this was at high altitude? Usual assumption is that forced-induction (FI) can be adjusted to compensate for altitude while normally-aspirated cannot

We took a long trip to Queenstown and East London. Even at coastal altitudes, neither car had an advantage over the other.

Note, I built this engine mainly with efficiency and economy in mind. Performance was nowhere on my agenda - but it was an unexpected (but welcome) by-product. This is why I also wanted a 5sp transmission with overdrive 5th - another sad story.

With my Jensen Interceptor 7.2L EFI project, I found that an overdrive transmission does a lot more for economy than a well tuned fuel injected engine.

[Woolfi]

If an EV12 with injection is running with lambda 1,0 and a EV12 with carbs is running with Lambda 1,1 at part throttle, I don't believe, that the gas consumption of the injected car is lower. Driving in the city would be different.
A long 2,88 diff and a 5th gear helps a lot to safe gas. At cruising my car has a consumption of roundabout 19 mpg.
Regards Wolfgang Gatza

[Woolfi]

Today I called my cousin and asked him for the race EV12 6,0L vs. Daytona. Immediately he was "on fire" to compare the acceleration of the cars between 50 km/h to roundabout 200 km/h (31mph to 124,3 mph) on a Autobahn. I will mount two cameras , make a video und put into youtube. I will post the link here.
He has a professionell oldtimergarage and is an amateur-racer. Therefore you can be shure, he will be able to "press" the Datona to 100%. See him in Hockenheimring:

I put my car on a balance. Without spare tire , without driver und and with tank half full the wight was 1480 kg. I found different numbers for the Daytona. Sometimes 12X0 kg und some numbers with 1600 kg. If the Daytona has 1600 kg, the power to wight relation would be a little bit better for the Daytona. But the torque curve of the EV12 is much wider. Maybe (???) this helps the EV12 a little bit.
Regards Wolfgang Gatza

[Woolfi]

In the magazine OCTANE 1/2018 is a big reprot aboiut the Daytone. In this magazin the wight is 1633 kg. Therefore 158 watts per kg.
My EV12 has exactly 1480 kg with half tank and without driver. If (???) my car has 310 DIN-hp, the watts per kg would be 154.
Regards Wolfgang Gatza