tuning

[aide 0]

If it was me;

 

- Standard air box and regularly replaced paper filter

- Oversized throttle body

- Smoothed as far as possible and port matched inlet tract

- Refurbed or new injectors

- Port matched and gas flowed head inlet side, mirror polished and port matched outlet

- If you could stretch to it, bigger valves and angled seat job

- smoothed standard manifold or 6 branch

- sports cat or decat

- Cams

- Remap

- Overbore

- Balanced rotating parts

- 3.68 final drive.

 

as guys above say, remap and cams get you furthest along the route, larger tb and 3.68 final drive has to be high on the list too.

 

Personally think that handling and stopping are more important mods than power at the outset, powers nothing without control to use well worn cliche.

[Kevin Bacon 5]

I was thinking of taking a stock inlet manifold and cutting it and improving the flow or making a new one completely with a different design. I've tried to find pictures of custom inlets but most stuff seems to just be for FI.

 

You'd be better off importing a US intake, which is the same as the 24V's. May aswell get the ECU and harness whilst you're there.

 

Save money, keep the standard airbox. BMC carbon thingy for £££ = what +/- 1 bhp?

 

7hp actually. Proven on a dyno on a bog standard MK3 VR6. I'm a big fan of standard airboxes but they ARE restrictive at WOT.

 

I saw a 2.8 VR6 at a recent dyno day do 200bhp / 210lbft

 

If it was an OBD2 Golf (96 on) then they do make more power. Standard ones average 190hp.

 

What time of year was that dyno pull done? Winter pulls add 10hp to a VR6 automatically.

 

200/210 is by no means an average result for the Golf.

 

I know of a freak Corrado that made 217hp as standard. Never saw another one like it.

[Metallix 10]

You'd be better off importing a US intake, which is the same as the 24V's. May aswell get the ECU and harness whilst you're there.

 

 

 

7hp actually. Proven on a dyno on a bog standard MK3 VR6. I'm a big fan of standard airboxes but they ARE restrictive at WOT.

 

 

 

If it was an OBD2 Golf (96 on) then they do make more power. Standard ones average 190hp.

 

What time of year was that dyno pull done? Winter pulls add 10hp to a VR6 automatically.

 

200/210 is by no means an average result for the Golf.

 

I know of a freak Corrado that made 217hp as standard. Never saw another one like it.

 

Standard ones are around 180bhp, maybe on some rollers they will average at 190bhp, there are some that seem to read higher.

 

The Mk3 I mentioned has been remapped, which is the main enabling factor to it's increased output, it was tested 2 weeks ago.

 

Winter doesn't really affect a dyno dynamics dyno.

The weather station corrects for this, if the air is colder/hotter/ less/more pressure,then a correction factor is applied to bring the figures inline with a standard set of environmental conditions.

These tests were done with a correlation car present (standard digifant 3x ABF engine) that constantly puts out the same figures each time one of these events are run.

 

The OBD1/2 thing never seems to go away...

"OBD relates to emissions monitoring.

OBD1 is the US EPA emissions monitoring std which ran to 94 then in 95 more parameters and calibration functions where included and this std became OBD2. OBD2 also runs of K line. For example all US/CDN MK3s or Corrados have a MILs, this was not a requirement for Euro vehicles as was 3 HEGO sensors, under floor catalysers and so on.

In Europe most of the these functions relating to US OBD are switched off! But the remainder can still be accessed via a K line. The remainder does not make the vehicle "OBD2". Many of the european vehicles like Merc, BMW, VAG and Opel communicate with the same protocols after 95 hence the rise of handheld diagnostic readers. You many find though that generic US "OBD2" tools do not work on many european vehicles due to differences in data sets.

In 95, Europe had EU1 emission stds and you find some of the hardware that benefitted US federal emission monitoring, fuel economy and emissions became std equipment on euro vehicles for our drive cycles.

There should be no drive difference (or small torque deltas) between a 93MY MK3 VR6 and a 96MY MK3 VR6.

The later MK3 VR6 may have the abilty to adjust individual batches of injectors and coil towers to compensate for manifold tract differences over time bearing in mind that these engines are designed to run at stoich during the majority of load conditions except WOT and high rpm."

 

I would have to see the BMC filter tested myself to buy those figures,

without seeing it in person I would suspect an old paper filter or some form of heat soak issue on the dyno.

The most restrictive part of the system is not the airbox on these vehicles.

I have seen vehicles with the 2.9 Corrado airbox & then with a cone filter, no difference to performance.

Could you guarantee that if a BMC carbon item was fitted here we would see a 7 bhp jump?

 

It's all good discussion though & your points on the US parts are interesting :)

[VAG-hag 0]

Mmmmmm thats a nice figure VAG-hag! Very interesting that you got that figure with just the cams map!

 

I am in discussion with stealth & planning on top end rebuild & 263's & a few other bits but im in a quandry at present as Im unsure whether to invest in a new exhaust first.......& the fact that the vortex solution im looking at is coming in at £1100!!!

 

my engine was fairly young at the time 65-70k ish & responded very well to the cams. i was pretty pleased & can say its the #1 mod ive gone for on the car.

[Kevin Bacon 5]

Standard ones are around 180bhp, maybe on some rollers they will average at 190bhp, there are some that seem to read higher.

 

The Mk3 I mentioned has been remapped, which is the main enabling factor to it's increased output, it was tested 2 weeks ago.

 

Winter doesn't really affect a dyno dynamics dyno.

The weather station corrects for this, if the air is colder/hotter/ less/more pressure,then a correction factor is applied to bring the figures inline with a standard set of environmental conditions.

These tests were done with a correlation car present (standard digifant 3x ABF engine) that constantly puts out the same figures each time one of these events are run.

 

The OBD1/2 thing never seems to go away...

"OBD relates to emissions monitoring.

OBD1 is the US EPA emissions monitoring std which ran to 94 then in 95 more parameters and calibration functions where included and this std became OBD2. OBD2 also runs of K line. For example all US/CDN MK3s or Corrados have a MILs, this was not a requirement for Euro vehicles as was 3 HEGO sensors, under floor catalysers and so on.

In Europe most of the these functions relating to US OBD are switched off! But the remainder can still be accessed via a K line. The remainder does not make the vehicle "OBD2". Many of the european vehicles like Merc, BMW, VAG and Opel communicate with the same protocols after 95 hence the rise of handheld diagnostic readers. You many find though that generic US "OBD2" tools do not work on many european vehicles due to differences in data sets.

In 95, Europe had EU1 emission stds and you find some of the hardware that benefitted US federal emission monitoring, fuel economy and emissions became std equipment on euro vehicles for our drive cycles.

There should be no drive difference (or small torque deltas) between a 93MY MK3 VR6 and a 96MY MK3 VR6.

The later MK3 VR6 may have the abilty to adjust individual batches of injectors and coil towers to compensate for manifold tract differences over time bearing in mind that these engines are designed to run at stoich during the majority of load conditions except WOT and high rpm."

 

I would have to see the BMC filter tested myself to buy those figures,

without seeing it in person I would suspect an old paper filter or some form of heat soak issue on the dyno.

The most restrictive part of the system is not the airbox on these vehicles.

I have seen vehicles with the 2.9 Corrado airbox & then with a cone filter, no difference to performance.

Could you guarantee that if a BMC carbon item was fitted here we would see a 7 bhp jump?

 

It's all good discussion though & your points on the US parts are interesting :)

 

Dyno Dynamics usually quote power at the wheels. Your numbers are brakehp I assume (can't possibly be whp from those mods) which means a flywheel correction factor was used, so ambient temps and barometric pressure do have a bearing on the numbers. Every standard VR6 I've seen dynoed on a winter's day makes 10hp more.

 

Yep, OBD is just a generic term for On Board Diags and emission control standards but it's about as 'standard' as SCART was, i.e. not at all. OBD2 on the Motronic used on the Golf brought with it some improvements over the 'OBD1' ECU. Significantly more maps and load sites, faster lambda, DC motor controlled idle, better fuelling etc etc. The older OBD1 2.8s made pretty much what VW quoted, 174hp, but the OBD2s always make a minimum of 185hp.

 

It was Stealth Racing who tested the BMC on a stock VR6. They also found 12hp on a standard MK4 R32 using the same filter. I've been going there since 1999 and I trust their numbers. They're just as skeptical of wildly high numbers as anyone. Do some research and you will discover it's well known how restrictive the R32 airbox is. It's no coincidence VW upped the intake snorkel diamater more than 30% for the DSG engine because the snappy gearchanges empty the airbox too quickly. They also increased the diameter of the MAF body. More food for thought, on my R32 conversion, it made 267hp with the corrado air box. With a BMC it makes 280hp.

There's no heatsoak issues with a BMC as the filter is enclosed. So might point is, yes the standard airbox is great at muffling resonance and assisting cylinder fill at part throttle, but they do hold the motor back a bit at WOT.

 

It is indeed good discussion ;)

[Stonejag 10]

So 240bhp and a similar torque figure should be a good figure to aim for. And then ill proberly assess it from there. What ill look to do then is exhaust manifold, decat and single box exhaust system, port and polish exhaust side, cams, on the inlet manifold there's a restriction up near TB on under side cut and plate that for better flow and may be the spark plug holes, lighten fly wheel if it can be done without being ruff. Stainless elbow in inlet from maf to give better flow and looks good. I'm sure I've missed something I was going to do. If I get board after all that in a few years then ill look at super charged

Suspect the inlet manifold underside thing you're talking about is for a 2.8 AAA inlet manifold.

Left is a 2.8 manifold, right is a 2.9 one. All Corrados should have a 2.9 ABV unless they've been fiddled with :)

 

More to the point, I need to get my head skimmed now I've had the pitting on the block side and thermostat flange welded up. Is it worth fitting bigger valves at the same time, for a n/a engine? +2mm inlet and +1.8mm exhaust valves aren't too expensive and there wouldn't be drastically more machine work to get it done at the same time. Planning to do some mild port-matching on it afterwards. Already got a CDA and decat fitted but I was going to add a six-branch exhaust manifold at the same time as fitting the head and 263s.

 

Cheers,

 

Stone

[Metallix 10]

Dyno Dynamics usually quote power at the wheels. Your numbers are brakehp I assume (can't possibly be whp from those mods) which means a flywheel correction factor was used, so ambient temps and barometric pressure do have a bearing on the numbers. Every standard VR6 I've seen dynoed on a winter's day makes 10hp more.

 

Yep, OBD is just a generic term for On Board Diags and emission control standards but it's about as 'standard' as SCART was, i.e. not at all. OBD2 on the Motronic used on the Golf brought with it some improvements over the 'OBD1' ECU. Significantly more maps and load sites, faster lambda, DC motor controlled idle, better fuelling etc etc. The older OBD1 2.8s made pretty much what VW quoted, 174hp, but the OBD2s always make a minimum of 185hp.

 

It was Stealth Racing who tested the BMC on a stock VR6. They also found 12hp on a standard MK4 R32 using the same filter. I've been going there since 1999 and I trust their numbers. They're just as skeptical of wildly high numbers as anyone. Do some research and you will discover it's well known how restrictive the R32 airbox is. It's no coincidence VW upped the intake snorkel diamater more than 30% for the DSG engine because the snappy gearchanges empty the airbox too quickly. They also increased the diameter of the MAF body. More food for thought, on my R32 conversion, it made 267hp with the corrado air box. With a BMC it makes 280hp.

There's no heatsoak issues with a BMC as the filter is enclosed. So might point is, yes the standard airbox is great at muffling resonance and assisting cylinder fill at part throttle, but they do hold the motor back a bit at WOT.

 

It is indeed good discussion ;)

 

Stealth, they do sometimes read a little high, I have seen extra peaks added to 16v plots from Stealth around 5500-6000 rpm.

These extra torque bumps are not present on a G meter, which doesn't lie, or other dynos.

 

I didn't think we were talking about the R32 airbox here. I am familiar with the airboxes on both Corrado & Golf VR though.

 

The only way to clear up the difference in dyno readout is to visit various rolling roads. Not something that many are prepared to do though.

VR6 owners do tend to head to Stealth & that is fine! It would be nice to see what the cars make on other brand rollers as an extra confirmation of the output.

Your 280 bhp figure was at Stealth too? Whether it would read more or less at another rollers, you cannot deny that is a great engine.

 

The figures I quoted were 100% flywheel, noway you would get that output @ the wheels from a 2.8 12v with only a few alterations.

[andyhudson 10]

Suspect the inlet manifold underside thing you're talking about is for a 2.8 AAA inlet manifold.

Left is a 2.8 manifold, right is a 2.9 one. All Corrados should have a 2.9 ABV unless they've been fiddled with :)

 

More to the point, I need to get my head skimmed now I've had the pitting on the block side and thermostat flange welded up. Is it worth fitting bigger valves at the same time, for a n/a engine? +2mm inlet and +1.8mm exhaust valves aren't too expensive and there wouldn't be drastically more machine work to get it done at the same time. Planning to do some mild port-matching on it afterwards. Already got a CDA and decat fitted but I was going to add a six-branch exhaust manifold at the same time as fitting the head and 263s.

 

Cheers,

 

Stone

Well that's ****ed that idea up. I'd only gone off pictures so no wonder I found little information on that mod. As for over sized throttle bodies where are people sourcing them? Another engine or after market?

 

When it comes to ITB's where do people think the main cost is? In the throttle bodies and hardware or the work involved in getting the management system to run on the car. Ive been reading up a little and its the change in management that puts me off all the hardware should be within my capability of making so making it less expensive?

[Kevin Bacon 5]

Stealth, they do sometimes read a little high, I have seen extra peaks added to 16v plots from Stealth around 5500-6000 rpm.

These extra torque bumps are not present on a G meter, which doesn't lie, or other dynos.

 

I didn't think we were talking about the R32 airbox here. I am familiar with the airboxes on both Corrado & Golf VR though.

 

The only way to clear up the difference in dyno readout is to visit various rolling roads. Not something that many are prepared to do though.

VR6 owners do tend to head to Stealth & that is fine! It would be nice to see what the cars make on other brand rollers as an extra confirmation of the output.

Your 280 bhp figure was at Stealth too? Whether it would read more or less at another rollers, you cannot deny that is a great engine.

 

The figures I quoted were 100% flywheel, noway you would get that output @ the wheels from a 2.8 12v with only a few alterations.

 

Stealth have Star Performance's old Sun Dyno. I remember Star Performance dishing out sensible numbers back in the day when places like AmD (when they were in Bicester) being very creative with the correction figures :D Here's an example: When I my old 16V Turbo MK2 was built (the Stealth uprated version with K Star and 4 x VR6 injectors), Stealth didn't have a dyno then, so the power run was done down the road at AmD. It measured 221hp. Roll forward a few years, Stealth got their Dyno, on went my car and it measured 190hp :lol:

 

The Sun is an old bit of kit now, very old, but since it's the only dyno I've used, it's kind of a good baseline. The measurments taken from standard cars on dyno days are usually spot-on as well, so it can't be too far off. For the purpose of tuning, being 10hp above or below a different dyno doesn't bother me much. The problem is with so many different makes of dyno and so many different operators, it's hard to trust any of them as being 100% accurate. 100% accuracy can only be achieved by taking the engine out and bolting it to a bench dyno under controlled conditions. Road cars have too many influencing factors. Light wheels and different gearing can affect the coast down losses, which will add more hp to the corrected value.

 

Yeah I just threw the R32 in there for discussion as it's a similar engine with a similar demand for air :D I do like the stock Corrado box, which is why I used it in my converison. I have no time for open cones or drilled OEM boxes. The BMC is the only aftermarket airbox I've seen that gives tangible results. The thing with the Corrado box is that lovely helmholtz resonance pipe that protudes half way into the airbox lid. It's brilliant for part throttle and removing it blunts the torque and makes a load of unnecessary noise, but at WOT, the funnelled down diameter of that pipe does restrict it.... to the tune of 7hp, as seen on Stealth's rollers at least, but let's say 5hp. That's not bad. All I've ever seen K&N open cones do is reduce power the same amount, especially when the engine bay is really hot.

 

Yeah I've only ever used Stealth's dyno. Not because I have a fear of getting a lower number elsewhere, but because I've been going there since 1999 and I've built up a really good rapport with them.

 

Yeah the R32 is a great motor. Held back by it's long crank throw and restrictive intake (at high rpms). There's definitely 100hp/litre in there but extracting it is expensive, so most folk go down the forced induction path instead.

[andyhudson 10]

If it was me;

 

Personally think that handling and stopping are more important mods than power at the outset, powers nothing without control to use well worn cliche.

 

completely agree with you there, its all about the corners. im just overhauling suspension now with polybushes and all new ball joints and track rod ends and i have koni coilovers. as for brakes ive replaced all the rear lines and mk4 calipers and then im looking out for something around 300mm mark for brakes