X flow head?

It's about time you did, it's amazing what you can learn form an experienced race driver :-)

Try a F1 car on the drag strip, everyone will laugh. If you want instant Mapped fuel systems are too slow.

The list you give are all just low powered slow accelerating stuff! Exept F1 (still slow in comparison) but here its endurance racing where niceties like drivability and fuel efficiency are important...

They are a compromise. Drag cars with 5000 bhp and 0 to 300 mph are not. They go!

You're doing well for making a fool of yourself tonight.

How many u seconds? 1-2?

Experienced people don't.

Seem to work well in Drag Racing..

Now that is advice I can use, thank you Homer!

I think the only engine upgrades i'll go for now are:

-Baffled sump to prevent oil starvation

-2.0 2E block which I have just located for £30

-Possibly a kent vernier pulley

Chassis and brakes:

-I'm not entirely sure what brake set up i'll go for but probably 256mm 16v brakes with some power discs and pagid pads and a 22mm master cylinder since it is the most cost effective solution

-the adjustable koni's should be ok, although I might see if I can find out more about stiffer spring

-I have located a safety dynamics half cage for £150 but I think he will come down a little if I buy the bucket seat he has for sale as well

-Front strut brace of some description, something like this by Eibach would be nice

I also found these 15" and 8" wide split rim jobbies: these 13" by 8" wide items I'm leaning toward the 13" wheels since cheap slicks seem readily available and the gearing should be fun (but will 256mm discs fit behind these alloys?), plus the 15" alloys have bmw badges although admittedly they could be levered out/sprayed they are also ET18.... and therefore might look a bit silly :)

5000bhp is Top fuel. Top Fuel don't use carbs. As you have already said they use a pump and spraybar - about the crudest form of fuel injection you can get short of a Wal Philips [1]. Top fuel run very rich mixtures, mixture control is not really needed due to wide range of mixtures that it will burn at, just have to ensure that doesn't run anywhere close to stoichiometric to avoid leaning out. Lots of the fuel that goes in comes out the other end - some of it decomposed to nitric acid.

Petrol needs precise mixture control, at or close to stoichiometric. Run rich the power drops off, very rich and it dies completely. Run lean it melts the engine [2].

[1] Tube with a butterfly and gravity fed fuel tap. Reports claim it was excellent, quick and easy to set up giving superb throttle response - on motors used in speedway and grasstrack. But they run on 100% methanol which is also run rich and couldn't give a monkeys about mixture so long as it doesn't lean out anywhere close to being stoichiometric. [2] Unless you have exhaust gas temp for individual cylinders and can set the mixture safely lean of peak. 1940's/50's aero engine fuel economy measure to get bombers and 100 seat aeroplanes with piston radial engines 1500 miles across Germany or the Pacific and back or 3000 miles across Atlantic without a splash and dash in Iceland.

If the EFI system you have doesn't have a map for acceleration enrichment get one that does. Or maybe your system does but you haven't found out where the map is. Just looks at throttle setting without any other engine conditions, if it opens it increases fueling. Unlike a pumper carb it doesn't just dump a gob of fuel in and hope, it's a measured amount, it will stay richer longer - until you stop demanding acceleration and on some you can set the decay rate.

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Experienced or stuck in the mud "we always done it that way" or even just technically clueless? Any one that get a carb off and open the fuel bowl can mess with jets. Can they get it right using seat of the pants? - no. Do they do dyno runs for all loads, pressures and temperatures they will run at? - no. How many pro let alone amateur teams have someone with them that can rejet correctly on the basis of the temp and pressure readings 1/2 hour before the race? All GP motorcycle teams did. If conditions changed during warmup or the race they are stuck with those setting, an EFI can adjust during the race.

Think most F1 teams would come into the category of "Experienced". Hasn't been a carb seen in F1 since Lucas made their system in the

60's and that was crap compared to modern domestic EFI. If carbs gave any advantage in engine pickup they would use them.

Also the rules for drag racing don't allow electronic fuel injection. Or everyone would be running it and races would be won and lost on ignition maps/traction control/launch control.

Fraser

Not sure the computer is the reason for the lag.

With my Holley, when I push the pedal down fuel is squirted into the manifold through pump jets and there is a burst of petrol smells all round as the engine blatts into much higher speeds. I've kinda assumed this is partly why the engine speeds up and is why there are these pump jets in the first place.

With my Scorpio, the fuel is injected according to the airflow meter when in open loop, and when in closed loop the fuelling strategy is determined by the emissions monitoring sensors.

When the engine speeds up, the information about emissions is necessarily out of date, etc. And no pumping raw petrol into it to richen it up. No wonder there is a lag, now I think about it.

Nope I am right. You however specialise in getting it back to front!

It is computing always takes a finite time so it is always playing catchup.

They are there simply because at any constant engine speed the carb alone fuels correctly. When you open throttle the airflow increase is instant because the atmosphere rushes in! The fuel though has much more weight, and does not speed up through the jets instantly. The acelerator pump pumps fuel directly as the throttle opens to cover the lean patch.

Yep. Not just airflow though, throttle position, engine acceleration in rpm per secs, and air and engine temps. Actually I though granadas used a map based on manifold vacuum rather than airflow meter? Whatever it orks the same way.

Actually its got ALOT more complicated than that nowadays.

Eh? The injectors are rather closer to the ports than most carbs, and the airflow from the carb will be much slower than the electronics.

That's probably because EFI systems are all about best emissions. Accelerator pumps anything but.

Air is already in the port, waiting, When throttle plate opens flow is there as soon as the piston draws it in.

The air flow meter, or manifold pressure sensor tells the computer which takes some time to calculate the required fuel so it gets it fractionally late.

Yep! And because computers are just not instant or close too it.

Actually it hasnt.

Unless you wish to explain in detail your version!!!

But for the richer mixture you've got to wait for it to travel from carb to cylinder?

Not so - it could be the TPS telling the ECU there's a sudden demand. Of course there are many ways of skinning a cat.

Also, the reduction in vacuum when the throttle is opened causes the fuel pressure regulator to increase the pressure.

Don't be silly. They can be as fast as you need for the application. And certainly faster than any carb can react.

Much faster but the amount of time is still noticible.