97 replies to this topic

[Nev]

And highly efficent DI VVT Engines like A20NFT

Better volumetric efficency - lower load - lower IAT.

 

Highest IAT I have ever seen on the racetrack is 49°C

 

Even with the small K04 Turbo.

 

The big EFR Turbo would make about 550 bhp with that amount of boost.

(at a higher rev range of course)

 

Yes, A20NFT is certainly a big step up in VE, particularly at higher revs I imagine.

 

On my car (just a Z20LEx) the highest IAT I ever saw was 39 degrees on my low torque map.

 

Would you be able to post a pic (or link to) your dyno plot please Dominic, I would be keen to see what it looks like. Thanks. Also, what ECU are you using?

 

Edited by Nev, 24 July 2016 - 02:36 AM.

[BadCop]

On my car (just a Z20LEx) the highest IAT I ever saw was 39 degrees on my low torque map.

 

 

 

I use the OEM ACDelco E39A - with my own kopp racing standalone software.

Without the standalone software the engine doesn't even start...

 

Will post dyno plot when its properly mapped.

 

To give you an idea here are the stock figures of the A20NFT on stock boost (22PSI), timing, cam timing etc.

 

It has a 3.5" Exhaust, bigger Intake, PWR 6" W2A Charge Cooler, light flywheel, underdrive pulley, mechanical waterpump and balancers removed - freeing it up from parasitic loss.

[Nev]

Is there an easy way to push peak torque further down the rev range? Presumably different cams, if they are easily available?

 

Whats the max torque or power it can safely make before the internals need changing?

Edited by Nev, 24 July 2016 - 09:23 AM.

[BadCop]

You could start by optimizing VVT and boost table.

The stock exhaust-VVT table is very conservative and the boost table drops at 6000 to prevent overspeed of the K04 Turbo past 6000.

 

Here are Stage 1 and Stage 2 Cams:

 

http://zzperformance...mance-cams.html

 

The OEM crank and rods are forged and should be good up to 500 bhp.

I even know a guy from the US called Matt whos A20NFT dragster has 600 bhp at the wheels with a bone stock longblock.

 

[siztenboots]

fairly boring cams will help low down torque , there because you have DI, you can try a pilot injection then a later main injection to try and get a better combustion mix. you can tune ignition for the flame front speed , at work I used to have access to AVL Fire software.

[BadCop]

All type of cams with higher lift will help. VVT just sets the phase ealier for better low down torque.

 

Yep the OEM software uses pilot injection - they call it split pulse.

 

 

Much smoother running. Without pilot injection it sounds a bit like a diesel engine at idle

 

 

[Doctor Ed]

Is something being altered at 5300rpm in the tables? On the altered torque map, it take a pretty big nose dive. Optimising the vvt will typically only have relevance in the low and mid ranges, I assume the cams just go to fully retarded over 4500 or so, so nothing left to gain there (unless the tables are 'trimmed' around 5500-6000 to turn the motor down)?)

[BadCop]

 

 

Exhaust cam advances to 7° at WOT.

Intake cam retards to 7° at WOT.

 

You can alter the values from 0 - 32°

0° means fully retarded intake and fully advanced exhaust.

32° is full advance intake and full retard exhaust.

 

0° is the park position without any oil pressure on the VVT system.

 

Higher numbers create more overlap.

The overlap in part throttle has the same recirculation effect as EGR valves on old engines.

 

The whole range is interference free.

Only when you change the cams you possibly have to use little spacers in the phaser to get your clearence back.

That means you can really try out some different setups.

 

@Ed: The 5300 nose dive comes from torque management.

Kicks in that early to prevent overspeed. They wanted to have a smooth rev limiter at 6250 I think.

OEM software reduces boost and slowly closes throttle.

This sort of TM revlimiter is very easy to drive and safe for the engine - unlike the old bang-bang fuelcut limiters that alter AFR and load 10times a second violently when you hit revlimit.

 

Without balancers you can safely set the rev limit to 7000.

But don't expect too much power above 6000 as the K04 Turbocharger is very small...

[Doctor Ed]

But but... I use the bang-bang as my shift indicator! Now what?! Lol Not too interested in pushing the 04 too hard, but on that torque unlimited curve, having power fall off from 5300 would be a bit too soft I think. Would be a better feel in the last few hundred rpm if it perhaps didn't make quite so much peak power, but held it through to redline, and have a slightly harder cut. (or if it could hold that peak power, and have a harder cut, that'd be sweet). Looks like there's some cam position changes in that 5500-6000 bracket that play a roll. My last motor ran fully variable vvt with 321deg cams. It's quite extraordinary how much you can play with timing but you really need to have it on a dyno and just run it back to back to back. Not something you can street tune at all. and when does a bigger fuel pump lobe come into importance?

[BadCop]

Don't worry Ed, we can even cut ignition if you like to rattatatta -tak tak bang bang, *smoke + flames*

Or cut fuel

Or simply make the TM slope steeper -think that's the way to go 

 

 

The OEM high pressure fuel pump lobe is sufficient up to 500 bhp.

 

Only if you want to run E85 we have to change it.

E85 has a lower AFR and therefore higher fuel demand.

 

[Rosssco]

Any thoughts on how an after-market TC system (e.g. Racelogic) would work or otherwise with the DI system?

 

I know the system won't work with low-impedance injectors (I think), and you need the ability to turn off mis-fire detection..

[siztenboots]

Don't worry Ed, we can even cut ignition if you like to rattatatta -tak tak bang bang, *smoke + flames*

Or cut fuel

Or simply make the TM slope steeper -think that's the way to go 

 

I am going to borrow that phrase , as I always ask customers if they like some over-run pops, depending on how much negative ignition timing I allow, you can have full rally car, antilag, I think my exhaust just fell off -30° , medium sounds like the Aston Martin Vantage at zero degrees retard , or just factory level almost none.

 

[color=rgb(40,40,40);font-family:helvetica, arial, sans-serif;] rattatatta -tak tak bang bang, *smoke + flames*[/color]

[BadCop]

Or just TAK TAK TAK like on the DUTTER Audi ("pink racing pig")

 

 

 

BTW: I will also start at Vilshofen this year - 15.Aug.

[Doctor Ed]

To say I'm looking forward to tuning this engine is an understatement Ughh, so much more work to do!

[Rosssco]

What sort of clutch is being used to handle ~400lb/ft..? I presume something that operates more like a on / off switch and nor suitable for road use?

[Doctor Ed]

I've got a guy who's put me together a full face organic clutch, with normal diaphragm assembly (light feel and saves thrust bearings) and uses the standard slave cyl assembly... Developed for a GM race series here in Aust. Rated to 600ftlb

[BadCop]

And I run a Southbend Stage 4 Plus that is rated at 475 ftlb for heavy cars and 550 ftlbs for cars under 1000kg.

 

It comes with a 5sec guarantee - You may slip the clutch 5 sec. long at 8000 rpm without loosing your warrenty:)

 

 

Pedal feel is normal. Perhaps a bit harder to push.

[Rosssco]

Cool. The Southbend looks a good (but slightly pricey) option

[BadCop]

You could also use the uprated ZF SACHS 3000970054 which is available for about 170 GBP.

 

They use it in the 1500kg Astra VXR up to about 500 Nm - so it should be fine in the much lighter VX.

[Rosssco]

Does that one fit - I thought the Astra used the F40 gearbox and large 240mm clutch (as opposed to our 228mm)..