Dump Valve vs Blow off valve

[haz@nocturnal_development]

debates are great as ya get more info rather than, 'no ya cant, yes ya can'

changing an ecu will not really change lag. lag is simpley waitin for ya engine to create enuf air flow to get the turbo spoolin, the turbo shouldn't have lag between gear changes if its still in its 'range'. i think the reason people feel lag, is not cos its there, but more so cos ya cant feel the G force that ya can feel on boost.

the way anti lag works is that the timin is crazily fettled so that the heat created from the 'different' timin will spool the turbo so that the wrc car will make around a bar of boost at idle, so it can happily run 4 bar round t track, without ever comin off boost.

antilag will knacker a turbo in minutes, hence they get a new 1 after each stage/set. i'd highly not recommend this to any1 unless usin it for racing.


also john i'd assume the different classes would run different amounts of boost.


haz

[johnd]

WRT the ecu I meant swap it out for a MOTEC or the suchlike where anti-lag is programmable. I meant that you mentioned you have a stronger turbo which should be strong enough to handle some mild anti-lag. Anti-lag, as per boost, is programmable (ignition retard/fuelling) so you can set it to hold, say, 0psi and as soon as you hit the throttle you are on boost. Yep, they do trash them on the WRC cars as most run about 20-25psi off throttle!!! The main stresses tend to actually be on the exhaust manifold/exhaust believe it or not but, yes, if set up agressively will destroy your impeller pronto.

I will add there is the facility to enable the anti-lag system on my engine but I haven't!! Water injection and intercooler spray, yes, as these are good good GOOD!

John

[haz@nocturnal_development]

i guess the turbo could take a bit but i feel its a bit excessive for a road car, no use on the strip, but mite come in handy for sprints etc.

wat scares me is the amount of heat created, summits gotta melt !

i'd only use water injection if there's a problem. it weakens the mix. it may let ya run a few more psi than without it, det etc but the water would be cancelling out some of that power so ya effectively runnin maybe 1psi more.

same goes for intercooler spray, its useful if the car has been stood for a bit, queue at pod etc, but on the move the intercooler should be effective on its own, if its not then ya need to go bigger.

both may work well but i think there's other ways.


haz

[johnd]

Hmm I have to disagree a bit....

I know someone who runs a 450bhp celica at santa pod and they use their anti-lag....basically it's great wherever you need to accelerate quickly but yes things will start fracturing and melting unless they are upgraded.

Ever noticed how your car always seems more powerful on cold misty mornings? That's the ECU advancing timing as detonation is being held at bay due to the cold, damp air. Want that power all year around, esp. in the summer? Fit WI and a spray. At any state of tune it is a better investment, in my opinion, than a bigger intercooler unless you are running high boost pressures. A lot of people think the biggest intercooler possible is best....actually the smallest possible is best as long as you are not detonating. WI and IS allow you to keep it as small as possible. I have both of mine engage progressively above 8psi to enhance safety in that boost range.

Just some food for thought

John

[overboost]

Ever noticed how your car always seems more powerful on cold misty mornings? That's the ECU advancing timing as detonation is being held at bay due to the cold, damp air.

John

It's actually because cold air is denser and requires more fuel for the same mixture. Therefore more fuel and air mix enters the cylinder and the car goes faster.

Ecu's will run to there maximum timing at all times, they only pull timing out if they hear detonation, due to poor fuel or the like.

[haz@nocturnal_development]

overboost is closer mate,

antilag is useless for the strip. at no point up the strip i'm off the throttle for that long for the turbo to come off boost.

i run 22psi with no water injection, using a front mount cooler and no co2 spray.
big coolers are better as they have a larger surface area to cool, hence cooler air.

i no a chap who has tried and tested w i on his 5 gtt, he now runs 25psi witout it

[johnd]

We're both right....that's what I meant! The air is denser as it is cooler and hence the ECU advances timing as much as it can. The moisture in the air helps to cool the intake charge and therefore counter detonation. I didn't want to sound like a chemistry teacher.

Wrong, there is a lot more involved in an intercooler being better rather than just being bigger. You've got fin types, pressure drops etc etc to consider.

I assume your mates WI was mapped correctly....it should have increased his power and made the a/f ratios safer if done correctly....if it didn't it wasn't.....I could talk supercharged WW2 fighter planes here but I won't!

I do feel this argument is getting a bit pointless or we are all misunderstanding each other....anti-lag is bad or useless for acceleration...hmmmmm?? The whole point of it being on a WRC car is to increase the acceleration rate out of a corner. WRC cars also run WI and Spraybars to protect the engine allowing higher boost.

QED

Why thank you, and good night!

John

[JohnTurbo]

Haha....or of course, use Lee's patented 'no dump' gearchange.