Do turbo coupes all have "turbo lag" unless modified? What does it mean exactly? Do you put your foot down and there is a slight delay in acceleration? Does this take some getting used to? Is it possible to have a modification done which will prevent it?

I am torn between getting another 20V NA with a very low mileage, 40,000, or a 20V turbo with a higher mileage, 99,000, both roughly the same price. So I am interested to know what the turbo is like to drive. I have decided an LE is probably VERY fast as it is 6-speed and perhaps I should look for a normal turbo first.

You're right with your turbo lag description. Particularly from low revs you wait for the turbo to spin up. It isn't a long wait - perhaps 1 second.

The 20V turbo and standard LE are about the same for performance with the same 220 BHP power output. The 6th speed would make for more relaxed motorway cruising, so would be a nice addition.

To drive, the 20VT is quiet, and very quickly reaches illegal speeds. The NA doesn't give you the thrilling shove in the back, but the sound of the NA engine on song, and the way that you can have more fun at legal speeds is nice.
The 20VT is more relaxed on long motorway runs.

From a value point of view the 40k NA is probably more interesting as there are plenty of 99k turbos around, it should also be a fair bit cheaper to run.

There is no significant difference between the performance between a "normal" 20vt and a 20vt LE, not when compared to a non turbo 20v.

All turbo-charged cars have turbo lag - how much is normally a function of the size of the turbo (larger turbo = more lag).

This video from Top Gear shows how bad turbo lag can be. If you find a 20VT that's this bad then it's broken

Various solutions have been tried to turbo-lag, but they're normally designed into the car, rather than being modifications. Some cars have used a combination of different sized turbos (a small turbo to spin up fast, then a bigger one to deliver the power) and VW have an engine which has both a turbo-charger and a super-charger.

Anyway, I'd say the 20VT is a very well-mannered car and they all come equipped with a handy device to allow you to limit how much power is delivered, conveniently located under your right foot

But you can always change dow a gear!!

Right, time to get my Geek on and lay the facts down on you mofos This is a real geeky bugbare of mine that nearly everyone in the world gets "lag" mixed up with "boost threshold" Two completely different things and not necessarily linked to each other either. I haven't clicked on that video but I bet it's there one where Gezza's in an Evo. THAT'S NOT LAG!! Makes me wanna pimp-slap the stonewash off his jeans!

First Boost threshold: This is what the vast majority of people mistakenly call lag. The boost threshold is the rpm that the turbo starts making positive boost at full throttle. The boost threshold is effected by the rotating mass of the comp and turbine, but depends more on the spec. of the turbine and turbine housing. And also the size of the engine and number of pistons. I won't go into details about trims and a/r, etc or this will turn into a mahoosive post, but suffice to say "smaller" turbine trims and "smaller" a/r's will generally (not always) make turbos with lower boost thresholds, but will also restrict power. COnversely, bigger trim and a/r higher boost thresheold, less restrictive.

Now lag, the one that nearly everybody talks about when they're really thinking about boost threshold!: Lag is the amount of delay in the turbo making boost when the throttle is opened and the rpm are above the boost threshold. The factors that affect lag are a bit more complex. Rotating mass has a strong affect. The design of the turbo itself is very important. the bearing system and aerodynamic design of the comp and turbine blades all have a strong effect on lag. It is very possible to have two turbos that can make the exact same power but one has less lag and lower boost threshold. Or even one turbo that has a high boost threshold but less lag than the other. Depends on the turbo spec and the engine spec.

With regards to Coupes, the stock 20VT (LE or not, they're both the same) has a relatively small turbo with a teenie-weenie girly-sized turbine and housing. Lag is almost non-existant. Anybody who thinks a stock 20VT is laggy needs to drive something ol' skool like Saab 900 Turbo. Now THAT has lag!

I can't even view this through the work filter but I'm going to assume it's the 'demonstration' of lag shown by Clarkson driving the FQ400...?

If so, then it isn't lag that is causing the other car to pull away; it's the turbo's boost threshold. The Evo's turbo does not spool enough at the revs used to generate power. In fact, it's probably just functionaing as nothing more than a restriction in the exhuast. Even so, it will still generate more than the other car (Stilo was it? I can't remember) at these rpms. The problem is, because they're both in top gear, the Evo will have considerably longer gearing and so be at a much lower point in its power band I.e . it is generating less ower.

Turbo lag is the time it takes a turbo to spool. At high speeds, right in the meat of the boost curve, it will still take a moment to spool. This is turbo lag. It will vary on the rpm of the engine and in some installations, may be almost non-existant. But all turbo cars will have some lag.

Damn...

Well there you go, every day's a school day. I should have gone with my initial feeling, which was to say that turbo lag was a very fast convict.

My thinking on lag (simplistic) is:

1) Turbos use air flow from the exhaust to spin the turbine. Until it has "spun up", this is causes restriction in the overall air flow to the engine compared to an N/A. Hence an NA Coupe may be faster off the mark (up to say 20mph).... before quickly losing out to the turbo model.

2) It takes a few seconds for the turbine to spin up and provide boost, which adds the second factor to the lag.

3) As I've got a bit older... my philosophy has changed to having more fun at legal speeds. (Going on a speed awareness course next week ) So out went my 160mph motorbikes with 100bhp+, and in in came my 60bhp bike, which handles much sweeter, and is genuinely more fun, becasue you can "rag it" without scaring yourself too much. Same with my NA Couoe. It sounds great at high revs, and is fast enough - 80mph in 3rd gear is no problem.

I wait to be corrected....

One of my pet peeves as well, the difference between the turbo's inertia to react to throttle input and the section in the RPM range where there's simply NEVER enough air to get it spinning. 'Threshold' you call it, I thought it was turbo GAP vs. turbo LAG but that again might be my memory fading.

Thanks. Hope everyone reads this post and stops complaining about the "huge turbo gap below 2500 rpm".

I agree that you can have a lot of fun at legal speeds. It does not matter if it is a 40mph limit, it is the fact that you can get there so fast! I used to hate red traffic lights but now I love them, having that opportunity to show off is enormous fun. Sometimes it feels as though the brakes only just stop me in time though, and that was scary at first but now I am more used to having to anticipate things more and use the engine to brake. All that information about turbos and how they work is really facinating. I have just got the tech manuals on disk and I am going to so enjoy learning all about coupes. I just learned something today - I had the wrong cap on the coolant tank, that is why it was leaking. Thanks Solo Ialia for putting the wrong one on! The new one fits perfectly, and looks totally different.

My turbos kick in plenty quickly enough for me. A lot of my driving is in traffic, so I don't want to be pointing and squirting in a jam. When I need (or want) some oooff, I just change down and floor it. Certainly enough to pin my ears back!

@Gripper My first motorbike had only 10 bhp! But it did 60, just about!

Note that the brakes often are in need of some work. They aren't the ultimate to begin with, but the pads also age badly and if they've overheated they are going to be crap forever. Also corrosion can build up underneath the pads, making them tilt and swivel so they overheat even faster (no contact patch to transfer the heat to the calipers) and will not 'match' the discs because of the movement. Also the insides may need a good cleaning - leave this to a specialist as there's a lot that you need to pay attention to AND some parts are easy to break. And fitting some Pagid Blue pads or so will give you a HELL of a big difference!

PS, I should also state that I would LOVE a Turbo Coupe... but the NA suits my budget, because if I had a Turbo, I WOULD spend £1000s which I don't have on mods etc.

The NA does most of the Turbo does, apart from the kick up the $ss, and I can get that from my Turbo diesel

... and from the better half, especially if you're found out to have bought a turbo...

Though if they're in good condition, even the standard 16NA brakes have no problems around, say, Spa.