Anti-lag set up

[junkie 0]

Im thinking of running a larger turbo for more punch, now its not too laggy at the moment, nice and driveable with power to boot so all round a good compromise.

 

If i wanted to use anti-lag which my engine management can do what will i need.

 

1 Which turbo so i dont destroy it?

2 Some sort of ISV set up?

3 Something else that i cant remember?

 

Also if i run a larger turbo that flows more air and i ran it at the same boost pressure to what i am currently using 1.5bar will i see any gains?

[Kevin Bacon 5]

Anti-lag is just a little ignition retard and more fuel basically, but done at the right time. More fuel = hotter flame temperature = faster moving exhaust gases = quicker spool.

 

Anti-lag usually goes hand in hand with launch control where stand alones are concerned.

 

You pull up to the line, set the rev limit to where you want it, say 3000rpm, dip the clutch and ready 1st gear, plant the gas and it won't rev any more than 3000rpm (using a combination of a soft limiter (ignition retard) and a hard limiter (spark cut)) and when the lights change, let off the clutch and off you go. Aswell as this, your anti-lag fuelling will be working too.....so you'll get lots of flames and pops and bangs.

 

Doesn't matter what turbo you use, it will work on any.... but the turbine blades will live a shorter life, aswell as the bearings etc.

 

Yes, a bigger turbo will give you more CFM for the same boost pressuer and therefore give you a harder kick.

[junkie 0]

Thats my point Kev that i could use it on my turbo but the life will be drastically shortened, i thought i read somewhere that the Garrett GT series can run anti lag all day long, now Owen Developments do a IHI/Garrett hybrid but im not too clued up on turbo's, but i know that the Owen hrbrid will still give me the IHI hot side for ease of fitment to my IHI exhaust manifold but the cold side is Garrett, so im getting the best of both worlds in theory, the fast spool of an IHI with the power of the Garrett, but on my engine its still going to be quite laggy hence the anti lag option.

 

But with that turbo im not sure on what the shaft is as IHI shafts are not rebuildable only replaceable i believe so im assuming its just the IHI exhaust housing, and Garrett compressor housing with a complete Garrett shaft in it.

 

Also i read a feature ages ago in (get my flame suit on) Performance Ford or Fast Ford that the shaft needs to be a "Maram Shaft"? for longevity and an ISV needs to be used to bleed some air into the inlet i think whilst the throttle is closed so that the turbo keeps spooling whilst the throttle is closed and when you open it its instant power from no lag, does that sound right?

[junkie 0]

Also im lead to believe its the boost pressure that will snap rods not power/torque so thats why im thinking bigger turbo at 1.5bar for more power without the need to change the rods???

[dinkus 10]

Scruffythefirst has a scary knowledge of all things turbo.

 

He doesn't own a Corrado but his Cosworth-powered Dax Rush is running Emerald and he's been doing a lot of research on anti-lag and launch control.

 

God knows why tho, the thing's already a rather large slice of pure mentalism :lol:

[junkie 0]

I remember that been built, does he come on here much nowadays, if your out there then share all your knowledge in this thread please :D

[junkie 0]

Link to the proposed Owen Developments turbocharger i was thinking of using

 

http://www.owendevelopments.co.uk/produ ... prodId=616

[VEEDUBBED 0]

Maram exhaust turbine shaft needed when using anti lag,it's the only metal that will withstand the kind of temps. associated with that mod.I don't see an IHI turbo having a Maram shaft,Garret terratory only i reckon.Every now and then these shafts pop up on eBay,very expensive components though.

What kind of engine manegment are you using?,i Don't reckon that digifant will hack it,the only ecu's i remember that used anti-lag were the weber/iaw P6,8 and L8 escort cos. jobbies,even then the idle valves had to be modified as did the internal parts of the ecu.

Why not plumb in a small shot of nitrous(25hp) jets?,you'll eliminate the lag instantly and also gain more power,i reckon that it'll also cost less compared to the cost of anti-lag that cost way back in '97 over 700 squids...

[junkie 0]

Thanks VEEDUBBED, if you look at the Owen Developments turbo thats possibly upto the job, i have e-mailed them just waiting for the response tomorrow.

 

I run the Haltech E6M stand alone management.

 

What exactly needs modifying though, as in not the ISV needs modding but what on the ISV?

[Scruffythefirst 0]

Ohhh My ears are burning :oops: :oops:

 

Anti lag (ALS) is a way of keeping the exhaust turbine of a turbo spinning against the resistance of a closed throttle plate and lack of exhaust energy. There are several versions of anti lag but I'm not going to get into EGR anti lag as its complicated and mountune want £3K for it.

 

The normal rally car ALS works by dumping fuel into the engine with air that is bypassed round the closed throttle plate, this would normally produce lots of power (simmilar to being at half throttle or therabouts) which is bloody dangerous if your trying to brake for a corner as the engine is pushing you forwards. The key to anti lag is that the ignition timing is retarded after TDC - (30deg ATDC rings a bell) so the piston is already on its downstroke so by the time combustion gets going the exhaust valve is opening and your not getting any effective work done into the crank. All this energy generated is blown out into the exhaust where it is rapidly expanding and very hot - ideal for keeping the turbine spinning. This unfortuately leads to very hot exhaust valves, turbine components and exhausts.

 

As the turbine is spinning when the throttle is closed you are generating boost with the throttle closed, this means you will have boost available instantly you open the throttle again, plus the turbo is already at full speed, meaning no lag. This won't help so much if you drop below the boost threshold rpm of the engine though, as although you will have boost when you re-apply the throttle, the exhaust gas energy will be lower than it would be at high rpm and the turbine speed can drop.

 

You can have various levels of anti lag, obviously the rally car boys run the maximum they can, meaning they produce full, if not more boost than they do at full throttle (air restrictors, lack of flow against a closed throttle etc). These need big air bypass valves, and generate massive temperatures. Maram 247 shafts are more heat resistant, ceramic coated turbine blades, turbo housings, exhausts and valves (often sodium filled) help manage the heat, but on a rally car it doesn't matter too much as turbo's get rebuilt after every event or changed during it.

 

Milder anti lag is still a benifit, and still particularly antisocial and can be done with a modified idle valve (to produce more flow), but it needs suitable software in the ecu. Some tuners have managed to retro engineer it into standard cossie ECU's, but pukka ALS is usualy the preserve of high end aftermarket ecu's like pectel T6.

 

There is another type of anti lag that works in the same way but doesn't require any modifcations to the idle valve, this is usually used for launch control and full throttle shift on turbo cars. If you hold down the clutch and the throttle fully open you'd normally just rev the car into the rev limiter and it would sit there banging its tits off. If the ecu retards the ignition so that fuel is ignited in the same way as anti lag you can produce boost without producing any torque on the crank. So if your accelerating and change gear with your right foot flat on the floor, a switch on the clutch kicks in the full throttle shift which retards the ignition enough to allow the engine to slow to meet the rpm for the next gear, while keeping the turbine spinning enough to maintain boost so you don't have to wait for the turbo to spin up again. This also works for launch control when properly mapped - you can sit in the line with the throttle fully down, the ignition strategy of the ecu keeping the engine at the desired rpm and boost level untill you drop the clutch at which point normal ecu functions kick in, albeit with you leaving your diff all over the start line as launching with full boost is hard on the car :shock: In these two strategies the throttle plate is acting as the ALS valve.

 

Do not use proper full on rally car antilag with anything other than a proper turbo designed to take it, otherwise you will be fishing bits of it out of your exhasut, intercooler and pretty much everywhere. Normal Garrett T series are ok for occasional mild ALS, and the full throttle shift / launch control but it will reduce their lifespan. The GT series have a ballbearing core which means they have a much thinner shaft and a non re-buildable core. I wouldn't use any ALS stuff with them. I don't know anything about other manufacturers turbo's.

 

On the subject of dump valves as its kind of related, they are normally only put in buy OEM manufacturers to keep noise down. Turbo's do not normally need them and are actually less laggy without them. This is because although the turbine will slow down quickly when the throttle is shut, the boost is maintained in the pipework so it takes less time to build tubine speed back up than re-charge the pipework with boost. Its especially noticable on quick gearchanges. The exception to this is T4's running very high boost as the shaft can snap due to the shock loading.

 

 

Right, part 2. Bigger turbo's produce more power for the same boost pressure

 

Forget about boost pressure - what matters to an engine is mass flow of air. A small turbo will have a small hotside leading to a resistance to the engine to pump air. This will give a good spool up but restrict the engines abilty to flow air and make power. A larger hotside will reduce this pumping inefficiency and allow the engine to make more power. The same goes for the compressor side - a larger compressor won't have to work so hard to produce the same boost pressure (in fact it should flow more air for the same pressure) leading to cooler intake temps and in turn creating less restiction to the hotside. The extra power will be at the expense of lag.

[dinkus 10]

Can I just interject my highly technical opinion here that the turbo chatter sounds way cooler than the pssshiiiiiiiit of a dump valve.

 

That is all :lol:

[Scruffythefirst 0]

As does french tunnels 8)

[dinkus 10]

Yeah, but I think that was more to do with you popping 2' flames out of the exhaust :lol:

[junkie 0]

Well there is a few things to ponder over :?

 

So would the last option be best for the anti lag?

 

How would flowing more air be beneficial to my engine been an 8v, as they are not very good at breathing as we all know, so with a bigger/laggier turbo, that by the time its getting into its sweet effiency range i would be strugglin to breath the extra flow of air hence why boost pressure on an 8v is slightly important.

[Scruffythefirst 0]

The more air you flow, the more fuel you can burn, the more power you make. Pressure is just flow thats stacked up in front of a restriction (in this case the engine) not going anywhere, making no power.

 

To be honest, I wouldn't bother with anti lag, just the launch control and full throttle gear shift - plenty of silly poping and banging, flames and broken gearboxes. If you drive smoothly and progressively, anticipating the road ahead with a correctly specced turbo it shouldn't be too bad on the road. Anti lag simply won't get through track day noise regs most of the time. A lot of people confuse spool with lag, anti lag won't make the turbo spool any faster.

 

No real idea on what the internals of your engine can cope with, but its most definately torque (and revs) that will snap rods (torque is usually a direct product of boost pressure).

 

If you intent on running anti lag, I'd get a maram shaft T34 in a suitable trim, but TBH, speak to an expert cos unless you've got an accurate idea of VE and mass air flow, all the compressor maps in the world won't help you.

 

GT28RS is a popular turbo good for around 300ish, a slightly different trim version GT28 gets about 360ish.

 

The more revs you can use, the bigger the engine and the better the VE will mean you can spool a bigger turbo in time to use the power.

[Kevin Bacon 5]

Can I just interject my highly technical opinion here that the turbo chatter sounds way cooler than the pssshiiiiiiiit of a dump valve.

 

That is all :lol:

 

:lol: Lol, you chavmeister!

 

"Wha wha wha wha" when changing gear may please the chavs, but it's

not doing the turbo any good.

 

If not running a BOV at all, it would be wise to do so on a turbo that has an anti-surge housing, or "Ported shroud" as the yanks call it.

 

I prefer to use a Dump valve and the big bastard 50mm tial I've got sounds more darth vader "raaaaaaaahhff" than phsssssiiiitt :lol:

 

The Synapse Synchronic BOV is quite an impressive bit of kit too. Totally eliminates surge.

 

Anti-lag etc and no BOVs (I ran no BOV on my old T25 16V T and it wrecked the compressor) are fine for race cars and weekend toys, but daily cars need more long term consideration.

 

Junkie, don't buy turbos from Owen, they are bloody expensive. You'd be better off importing it from atpturbo.com

 

Agree with Scruffy, don't bother with ALS, just get a bigger turbo and learn to keep it in the torque band with measured throttle inputs, plus you have a standalone so you can alter the fuelling and timing to improve off boost performance. Unless you use inconel exhaust valves, you'll fry those very quickly and I've also seen valve guide seals over heat, crack and let oil through aswell......

 

Nice idea, but not practical for daily use :lol:

[Scruffythefirst 0]

"Wha wha wha wha" when changing gear may please the chavs, but it's

not doing the turbo any good.

 

If not running a BOV at all, it would be wise to do so on a turbo that has an anti-surge housing, or "Ported shroud" as the yanks call it.

 

What a load of rubbish, surge has nothing to do with dump valves. Surge occurs when the compressor is too big for the turbine, it generated a massive boost spike as it comes on boost, the ecu responds by opening the wastegate and boost drops off as the huge compressor stalls, ecu shuts wastegate turbo generates big boost spike and so on. Anti surge housings are a compromise as they slow the turbo's ability to spool by bleeding air from the edge of the compressor housing back into the inlet. Much better to get a properly specced turbo in the first place if you ask me.

 

All the turbo manufacturers I've spoken to say no need to run a BOV unless running a turbo way off its compressor map and shaft speed, and in that case you might as well get a different turbo. The only damage its likely to do is to the shaft, and the experts seem to think a BOV can excacerbate the shaft loadings in some cases. OEM's fitted recirculating BOV purely to get rid of the noise.

[Kevin Bacon 5]

I'm talking about reverse airflow surge when you close the throttle you berk, which is different to the boost surge you are talking about.

 

The "Cha cha cha" is the sound of the air flow bouncing back through and over the compressor.

Anti-surge housings allow some of that reverse air to escape past the inducer blades, which reduces turbine shaft vibration and therefore increases bearing life.

 

Not running a BOV is actually a load of rubbish if you ask me.

[Scruffythefirst 0]

Well the poeople who build my turbo's say no need. I'll stick with them as they're the ones upholding my warrenty.

[junkie 0]

Jabbasport were trying no BOV on their corrado but it may be different as the G60 throttle body has the 2nd butterfly so when the throttle is closed the 2nd butterfly opens and vents the boost anyhow so as i say it is prob still different.

 

So can you reccommend a different turbo you guys?

 

Its not exactly a daily my car so if its something i could use occasionally that would be good regarding ALS/launch control/full throttle gear changes.

 

Im not a chav in the slightest but i like the dump valve :lol: so thats staying, people dont expect that sound from my car so in my book its cool 8)

[VEEDUBBED 0]

Hey scruffy,i'd just wanted to say that your write-up was exellent mate,well packed with info.

Before i forget,Blue sprint motorsport used to modifiy ecu's to run anti-lag,might wanna give them a call.

[junkie 0]

I dont need to modify it though it has the function built in already but i need the parts to get it working if i was to go down that road.

[Scruffythefirst 0]

What turbo do you currently have and whats the engine spec. What Ecu? Mountune do all the bits you'll need for ALS although they're very expensive. Alternatively, port your ISCV as much as possbile and see how much effect it has, you'll have to get the ecu set up as it can cause idle problems without using a seperate valve.

 

If you want to use anti lag all the time, get a turbo designed to handle it. (bear in mind proper antilag gets expensive when you consider just a maram 247 shaft is £700)

 

The bottom line is really, how much power do you want / can your bottom end handle and are you prepared to make other mods to suit the turbo. (these are ballpark figures, get someone who knows your engine to spec the exact turbo, trim and housings etc)

 

GT40 external gate 500-stupid bhp no ALS

GT30 internal /external gate for 400-550bhp but forget antilag

T4 should do 500Bhp but will be laggy as hell.

or if you want some sensible numbers, a maram shaft T34 for 300-400bhp

GT28RS for 300-360ish other trim GT28's for a little more (forget antilag)

 

Wouldn't hurt to get everything ceramic coated as anti lag will cook everything in your engine bay, although ceramic coating the manifold can lead to heat problems for the turbo and valves. Might not be a bad idea to lockwire all your turbo and manifold nuts as it has a habit of loosening them pretty quick.

[junkie 0]

What turbo do you currently have and whats the engine spec. What Ecu? Mountune do all the bits you'll need for ALS although they're very expensive. Alternatively, port your ISCV as much as possbile and see how much effect it has, you'll have to get the ecu set up as it can cause idle problems without using a seperate valve

 

Im not running an ISV currently, from cold its bad, when warm its spot on.

Engine spec on 8v G60

 

1900 (1870) 83mm bore

JE 83mm forged pistons

144mm 16v rods

Lightened & balanced crank, rods, flywheel

Big Valve Head ported & polished

Ported throttle body

Matched exhaust port

Custom 2.5" Blueflame downpipe

Custom 2.75" Blueflame exhaust

Piper 285 camshaft

Vernier Pulley

IHI VF22 Turbo + ported wastegate

Bailey dual piston dump valve

Jabbasport Cast Manifold

Jabbasport baffled sump

440cc injectors

16v external fuel pump

Aquamist Water Injection

Pro Alloy FMIC

Mocal 13 row oil cooler

MK3 Golf Alternator + various pulley's

Haltech E6M stand alone engine management + in car boost adjustment and trim

Custom Jabbasport map

Wasted spark ignition

Polo crank position trigger wheel

x3 Vibratechnics competition engine mounts

Low temp thermostat

Slimline radiator fan

Silicone & alloy boost pipes

Jabba custom heat shield

JR cone air filter

Trimsport dipstick

Simon_Corado dyno.jpg[/attachment:03b3b]

 

 

If you want to use anti lag all the time, get a turbo designed to handle it. (bear in mind proper antilag gets expensive when you consider just a maram 247 shaft is £700)

 

Not fussed about all the time just occasional use if thats possible and ouch thats expensive but if needs must.

 

The bottom line is really, how much power do you want / can your bottom end handle and are you prepared to make other mods to suit the turbo. (these are ballpark figures, get someone who knows your engine to spec the exact turbo, trim and housings etc)

 

It should be ok just need to do the rods which that was the plan anyway.

 

 

Wouldn't hurt to get everything ceramic coated as anti lag will cook everything in your engine bay, although ceramic coating the manifold can lead to heat problems for the turbo and valves. Might not be a bad idea to lockwire all your turbo and manifold nuts as it has a habit of loosening them pretty quick.

 

Sounds like its going to be fun then.

[Scruffythefirst 0]

Looks like its got the right sort of bits in it.

 

GT28 in a slightly bigger trim than the RS (disco potato) should see you right. If you just use the antilag occasionally (and launch control etc) then you can probably get away without too many mods, although having it locked out by an EGT probe would be good if your ecu can do it. Don't forget you can get the GT series turbo's with normal journal cores which means you get the faster spool from the improved housings and impellors in a core you can re-build for a very marginal increase in spool / lag.

 

I'll see if i can dig out the exact trim i'll be going for when I upgrade.