Well, I may be some time ...

[Lowtimer]

when driving it on boost in second, and changing up when it hit the red line, you had a reasonable while before boost really appeared in third, and again from third to fourth.

Something's not quite right with it, if that's the case. If you are changing up at 6000 rpm in second you are straight into third at 4000 rpm and should have boost straight away. Out of third at 6000 rpm, you are taking fourth at 4500 rpm and there should be no lag at all.

It probably just has some little leaks in the pipework here and there.

 

[loc944]

Carefull Steve, at this rate you will have more 944's lying around than Alasdair. What's your plans for this one?
Need to meet up again soon for a chat, just not in the next 8 days(holiday).

P.S. need to update your signature.

Cheers Alan.

 

[944 man]

ORIGINAL: barks944

Don't forget we are talking about an ancient turbo and a very simplistic engine management system here. There's a hell of a lot to be improved on here. I'm looking at a borg warner ERT turbo which has an aluminium compressor wheel, gamma titanium turbine, ceramic ball bearings and possibly twin scroll. This will drastically reduce the inertia of the turbo and twin scroll really helps get the best out of the turbine at low RPMS. Couple that with an injection system that actually understands boost pressure and doesn't retard the ignition all the time because it doesn't have a clue what is going on and you will have a very different animal . I'm going to be aiming for ~2500rpm spool and >350bhp, but we shall see!

Twin scroll turbos are very difficult to get working properly. Thats quite a target you are setting yourself there*...

Simon

* although; I remember thinking the same a year or two ago when you said that you were going to reverse engineer the Motronic... []

 

[TTM]

ORIGINAL: zcacogp

I prefer the progressive power delivery of a normally-aspirated engine; driving an S2 briskly is a function of getting the right revs in the right gear; driving a turbo briskly is more a function of getting the request for power in enough in advance, and enjoying the power when it arrives. (And I am aware that the turbo I experienced was modified, and therefore probably less laggy than a standard one.)

I have to agree with that.

When I bought the turbo I thought the boost rush would eventually take over the driving habits I developed at the wheel of the S2, but it just didn't. Now that I've tweaked the turbo enough to make it feel like it's normally-aspirated I'm having fun with it like I never had before, but it has been a long, painful, frustrating and expensive experience.
At the risk of saying it again for the nth time, the S2 remains the better car!

Anyway, being able to run both and appreciate both characters is quite rewarding - Oli, I'm sure you could find a place for another 944 []

 

[edh]

ORIGINAL: Lowtimer

when driving it on boost in second, and changing up when it hit the red line, you had a reasonable while before boost really appeared in third, and again from third to fourth.

Something's not quite right with it, if that's the case. If you are changing up at 6000 rpm in second you are straight into third at 4000 rpm and should have boost straight away. Out of third at 6000 rpm, you are taking fourth at 4500 rpm and there should be no lag at all.

It probably just has some little leaks in the pipework here and there.

Definitely not right. With an MBC and DPW it should be making well over half a bar at 3500, and 1 bar at 4k. The only time I found a problem was pulling onto roundabouts from a stop, when it takes forever for the turbo to spool up.

Better have another drive when it's sorted

 

[scam75]

ORIGINAL: edh

ORIGINAL: Lowtimer

when driving it on boost in second, and changing up when it hit the red line, you had a reasonable while before boost really appeared in third, and again from third to fourth.

Something's not quite right with it, if that's the case. If you are changing up at 6000 rpm in second you are straight into third at 4000 rpm and should have boost straight away. Out of third at 6000 rpm, you are taking fourth at 4500 rpm and there should be no lag at all.

It probably just has some little leaks in the pipework here and there.

Definitely not right. With an MBC and DPW it should be making well over half a bar at 3500, and 1 bar at 4k. The only time I found a problem was pulling onto roundabouts from a stop, when it takes forever for the turbo to spool up.

Better have another drive when it's sorted

+1. Limiter in 2nd then full throttle into 3rd produces almost no lag at all. As does same drill 3rd into 4th. I would say about a second elapses until full boostification is again experienced!

Stuart

 

[Lowtimer]

A second? A second is a long time... Nothing like as long as a second, surely?

 

[simkin911]

[/quote]


+1. Limiter in 2nd then full throttle into 3rd produces almost no lag at all. As does same drill 3rd into 4th. I would say about a second elapses until full boostification is again experienced!

Stuart
[/quote]

Seeing as Oli is in London now, I think you'll just have to make the short trip to road test it yourself Stuart and comment further as an experienced Turbo owner !

 

[JamesBall]

ORIGINAL: edh

Definitely not right. With an MBC and DPW it should be making well over half a bar at 3500, and 1 bar at 4k. The only time I found a problem was pulling onto roundabouts from a stop, when it takes forever for the turbo to spool up.

Better have another drive when it's sorted

+1. Almost no perceptible lag when going through the gears.

In fact I think the term lag is often used to cover two different things: 1) lack of power when in the rev range when there arent enough exhaust gases to spin the turbo and 2) the slight time delay when in the right rev range for the exhaust gases to get the turbo spinning. I would call number 2 "lag" but not number 1. And it is number 1 that is the bigger issue to me.

 

[scam75]

ORIGINAL: Lowtimer

A second? A second is a long time... Nothing like as long as a second, surely? 

A second from dumping the clutch on the limiter to being on full boost again in next gear is not a long time!

Stuart

 

[zcacogp]

ORIGINAL: James Ball
In fact I think the term lag is often used to cover two different things: 1) lack of power when in the rev range when there arent enough exhaust gases to spin the turbo and 2) the slight time delay when in the right rev range for the exhaust gases to get the turbo spinning. I would call number 2 "lag" but not number 1. And it is number 1 that is the bigger issue to me.

Sorry to be really slow, but these sound like the same thing to me (unless the 'rev range' in the first instance is simply a rev range where there will never be enough exhaust gasses to spool the turbo.) Have I missed something?

Another Q on this topic. More general tho'. The boost gauge in the instrument binnacle read 1 when the car wasn't running - I presume this indicates "1 atmosphere", i.e. normal air pressure. However, this dropped below 1 for most of the rev range. I am aware that the inlet manifold pressure of a N/A car is below atmospheric most of the time (it's how the air is sucked in), but expected it to be above atmospheric most of the time with a turbo. Does this reading of less than 1 indicate that the turbo wasn't producing any pressure at all?

(This may be a simple question with a complex answer, and if so then please be patient with me ... )


Oli.

 

[JamesBall]

Oil - I meant exactly as you said. My point number 1 occurs between 800rpm and 3000ish rpm. Point number 2 occurs above 3000rpm. Lots of people drive turbo cars and call the experience of putting your foot down at low revs and having to wait for the revs to rise to the point where the turbo starts spinning as lag where as I wouldn't call the lack of power at, say, 1500 rpm lag.

Regarding your second point, my understanding is that the boost gauge reads below 1 for the same reason as in an NA car - at these times the turbo is producing no pressure.

 

[Fat Albert]

With larger turbo cars you learn Boost Management, ie keeping the turbo spooled up and ready when you need it, my 3rd (of 6) SAAB Turbo had the dustbin-sized High-Output Turbo (HOT) fitted and the lag was terrible, but most of the others were Light Pressure Turbos (LPT) that were then chipped up to Aero/Viggen levels so tended to provide instant boost when needed. I also had an Impreza WRX (small turbo) but drove the STi (Big Turbo) on track and the difference was marked (The WRX was far more useable on road). A mate had an Integrale Evo also with the dustbin-sized blower and lag to match.

In the HOT SAAB I learned to prepare for an overtake or roundabout exit by either dipping the clutch and blipping the throttle or applying throttle early and lifting off, that way you could spin the turbo up and you would get that satisfying kick in the back when you were ready to unleash the LSD-overwhelming torque....

My 220 has the Promax boost enhancer that I believe smooths the delivery out a bit, but I still pre-spool for overtaking, I find myself in the torque-hole less often than the SAAB, but can sometimes still bog-down when you're not concentrating.

Of course the flipside is that you can deliberately let the boost come on as you exit a roundabout to snap the back end out.....

My Wife's 730D used to often get stuck in a hole, especially when the gearbox got confused, the 535D has the twin turbos so has the best of both worlds, with the ickle one filling in whilst the dustbin spools up

 

[DavidL]

Our wrx has far less lag than my 944 - barely noticeable really and real time performance is very similar.

ETA woohoo 1000 posts - must get out more. Don't I get something beyond my 5 stars?

 

[simkin911]

Anyways, parking the discussions of the "boooooost" for a moment (many thanks for all the comments by the way - I will soon get Sulzeruk to have a look over the car). Here's a few snaps taken this evening...

I really like the linen interior - makes the cabin very bright compared to the grey or black interiors.

 

[zcacogp]

She's come up well, Steve. Nice piccies - thanks.

(Although worrying in another sense. I know how rotten that car is, and yet it can photograph very well indeed. Therein lies a lesson in taking care to anyone who buys a 944 without a good, close inspection ... !)


Oli.

 

[deafasapost]

ORIGINAL: simkin911

Anyways, parking the discussions of the "boooooost" for a moment (many thanks for all the comments by the way - I will soon get Sulzeruk to have a look over the car). Here's a few snaps taken this evening..

I really like the linen interior - makes the cabin very bright compared to the grey or black interiors.

love that pic of the rear, them there arches are uber sexy!!!

i think linen is a cracking interior colour, and as you say, really brightens up an interior.

 

[simkin911]

Quite. However, you can't see the sills when you're in the driving seat so all is well! [] And it will be shortly anyway.

 

[Lowtimer]

The boost gauge in the instrument binnacle read 1 when the car wasn't running - I presume this indicates "1 atmosphere", i.e. normal air pressure.

Correct, and when you turn the key and the engine starts to suck against the closed throttle, the needle will dive left, to almost the bottom stop, as there is lots of suction in the inlet system, (i.e. manifold pressure is less than atmospheric).

However, this dropped below 1 for most of the rev range. I am aware that the inlet manifold pressure of a N/A car is below atmospheric most of the time (it's how the air is sucked in), but expected it to be above atmospheric most of the time with a turbo. Does this reading of less than 1 indicate that the turbo wasn't producing any pressure at all?

It will be below 1 bar almost all the time you are driving around, because the engine produces a maximum of around 140 bhp at peak power RPM and 1 bar, and probably produces around 80 bhp at say 3000 rpm and 1 bar and you are almost always using less power than that unless you are accelerating hard, going up a steep hill at high speed, or cruising at well into three figure speeds.

However, any time you have the throttle wide open, even completely off boost at say 1300 rpm, it should indicate just under 1 bar (atmospheric, less the pumping losses past the air filter and throttle body ), rising above 1 bar as the turbocharger starts to contribute, which on my car is around 2500 rpm.

 

[pauly]

ORIGINAL: TTM
At the risk of saying it again for the nth time, the S2 remains the better car!

I've never understood this opinion, before I had one anytime I saw an S2 badge on the back of a 944 I thought sheep in wolf's clothing.