Is the 4.2 really that slow ?

[Awebber]

I am a recent owner of a 1997 4.2 Cerbera and I'd like to see what other owners make of the acceleration of the car. Having come from my 2000 Jaguar XJR I was expecting the performance to outdo this (as on paper it does) but either I'm driving it badly or the engine is only working on four cylinders as it is flat unless you rev the nuts off it. In fact up to about 3,500 rpm I would say it is pretty ordinary and I would be afraid to even consider taking on a small hot hatch for fear of being left in it's 1.4 litre exhaust smoke.

Is there a knack to driving these cars and do you have to adopt the Honda VTEC approach and wring every last rev out of the car to post some decent acceleration ? I love the car to bits in terms of look, the interior and the noise but I'd like the speed to go with it.

[mark.rowe]

I'd say something is definately up with your engine somewhere, might be worth getting someone like joolz etc to take a look. Maybe blocked cats etc if its as sluggish as you say.

I've just got a standard 4.2 and it'll out accelerate practically anything i've come up against so far on the road.

The closest anything came to beating me was a red griff 500, we both went for it coming up a slip road and onto the A1. The griff started to creep away when I was in 2nd only due to the fact his tyres seamed to grip a lot better than me and I was fish tailing a bit. But as soon as I got grip I was away past.

No matter what revs it seams to pull when you burry the loud pedal. If I floor it at say 1.5k it gives a very VERY slight delay but by time it hits 2k the needle rockets round! Then when it hits 5k things get even better!






>> Edited by mark.rowe on Thursday 14th April 00:03

Slow u might want to have ur car looked at,mine is a bat out of hell



Eddie 4.2

[Mad Mark]

I know it sounds stupid, but make sure you are putting your foot down quickly and ALL the way. They've got very long pedal travel.
I've only got little legs, and when i got my first Cerb it took me a little while to realise that i wasn't even hitting the floor with the go pedal, i've literally got to point my foot to get full travel. But then I am only a short arse.

[J_S_G]

My 4.2 widdled all over my XKR in terms of straight line speed (and cornering with the Nitrons on, for that matter).

Admittedly, the low-end torque on the AJ8 Jag engine has a serious advantage (when combined with the supercharger), but by 3000RPM the power:weight of the Cerb's definitely coming into its own. Above 4-5k there's no contest.

Still, I'm on 1400 miles in the Jag with the only bill being a down-sized front numberplate that was already missing when I bought it, and the only niggle being that if you REALLY slam the arm-rest down, the ash-tray glides open.

Pluses and minuses...

Plus, mine sounds like a proper V8... ner ni ner ni ner ner

[mark.rowe]

J_S_G said:

Plus, mine sounds like a proper V8... ner ni ner ni ner ner

You can't beat the AJP's motorbike style sound when flat out through a tunnel though!!
Makes you feel like you're in the Monaco GP!

You're XKR looks amazing by the way, I always think of them as a sensible, comfortable cerb!
I went from XJS to Cerb, and was so close to buying an XKR before I decided upon the cerb.

[J_S_G]

mark.rowe said:

J_S_G said: Plus, mine sounds like a proper V8... ner ni ner ni ner ner You can't beat the AJP's motorbike style sound when flat out through a tunnel though!! Makes you feel like you're in the Monaco GP! You're XKR looks amazing by the way, I always think of them as a sensible, comfortable cerb! I went from XJS to Cerb, and was so close to buying an XKR before I decided upon the cerb.

Cheers.

That's exactly how I see them, too. Don't think I'd buy a standard one, but with all the Paramount kit on it, it looks so much better (not to mention the handling, sound, etc). Speaking of which:

www.paramount-performance.com/real/full-grandprix-exhaust-system.wav


You should hear the engine under load. Imagine a Merlin V12 powered Spitfire in a steep dive.

Still miss the Cerb, naturally

[RUSSELLM]

J_S_G said:

REALLY slam the arm-rest down,

Snob

I'd have to agree with the vtec theory, I'm of the opinion that if they've give you over 7000 revs to play with, your not going to great performance at 2-3k revs,

Give the mother some stick

[Tam Lin]

RUSSELLM said:

.. if they've give you over 7000 revs to play with, your not going to great performance at 2-3k revs

Yup, though Mark Adams/Austec and Joolz/Emerald can add a bit of torque around 3K. Interestingly, my engine is pretty much done, power wise, at 6000 rpm, so going to 7000+ only causes additional wear. Maybe time to find some noisy cams and really remap the b*gger

[joospeed]

Interestingly, i refuse to remap the 4.2, as the power gains i've seen mave been minimal to the point that it's not worth doing. Much better to spend 1K on a week away with the missus for ultimate feel-good factor. 50bhp gain on a 4.5 for 1k is well worthwhile, the 5 or 6 bhp gains I've seen on the 4.2 are definately not worthwhile.

[paulk]

do you know of any reason for this Joo?

[joospeed]

paulk said:

do you know of any reason for this Joo?

yes, teh mapping for teh 4.2s seems to be very good already .. almost as if someoe who knew what they were doing had been involved! unlike the 4.5s where they're oh-so easy to improve upon.

also the restricted inlets on the 4.2 limit the airflow available, and HP is all about airflow.

[350matt]

But surely its still worth it for the driveability gains?Our works 4.2 is pretty nasty to drive at low throttle openings?

Matt

[simonsparrow]

350matt said:

But surely its still worth it for the driveability gains?Our works 4.2 is pretty nasty to drive at low throttle openings? Matt

I was thinking about that for mine, but I improved it a lot with new throttle pots. Its still a bit rough, but much better than before. I had previously added Magnecor leads and new throttle linkage ball joints, which also helped a bit.

New TPs have made the most difference.

[joospeed]

350matt said:

But surely its still worth it for the driveability gains?Our works 4.2 is pretty nasty to drive at low throttle openings? Matt

erm i made no impact on driveability either .. the 4.2 and 4.5 are chalk and cheese .. i would say if your 4.2 is that bad there's a fault that needs addressing. the 4.2 is very nice to drive .. light years ahead of a std 4.5 which is one reason I recommend the 4.2 over the 4.5 for the everyday driver .. it really is a sweet car to drive as std.

[mark.rowe]

joospeed said:

erm i made no impact on driveability either .. the 4.2 and 4.5 are chalk and cheese .. i would say if your 4.2 is that bad there's a fault that needs addressing. the 4.2 is very nice to drive .. light years ahead of a std 4.5 which is one reason I recommend the 4.2 over the 4.5 for the everyday driver .. it really is a sweet car to drive as std.

I'll have to agree there, mine seams to drive really well pretty much all of the time. If i've been out for a good blast round country roads, dual carriage way etc, then return to city driving it feels a little lumpy around 2-3k revs, but then it seams to adjust itself and runs relatively smooth again after a mile or so.

[Tam Lin]

joospeed said:

erm i made no impact on driveability either .. the 4.2 and 4.5 are chalk and cheese .. i would say if your 4.2 is that bad there's a fault that needs addressing. the 4.2 is very nice to drive ..

Hmm, not sure my experience reflects that entirely, though I may be seeking a placebo to feel better about an increasingly expensive month*.

I realise that my engine may have a yet-to-be looked into secondary issue, but even comparing it as it was in the rudest of health (i.e. straight after a service), I would say that adding ten odd sites low down in the mapping does improve driveability around town a lot.

*(Just in case anyone misunderstands, Joolz did not modify/replace our 4.2s ECU. The day after the Austec rolling road session, the fingers went on the clutch)

[bruciebabe]

Awebber said:

I am a recent owner of a 1997 4.2 Cerbera and I'd like to see what other owners make of the acceleration of the car. Having come from my 2000 Jaguar XJR I was expecting the performance to outdo this (as on paper it does) but either I'm driving it badly or the engine is only working on four cylinders as it is flat unless you rev the nuts off it. In fact up to about 3,500 rpm I would say it is pretty ordinary and I would be afraid to even consider taking on a small hot hatch for fear of being left in it's 1.4 litre exhaust smoke. Is there a knack to driving these cars and do you have to adopt the Honda VTEC approach and wring every last rev out of the car to post some decent acceleration ? I love the car to bits in terms of look, the interior and the noise but I'd like the speed to go with it.

Never underestimate the force of the Jag supercharged V8. Squeeze your right foot and instant globs of torque provide massive thrust. The well developed suspension allows you to use more of it more of the time than in a lot of other cars. In many real world situations it is faster than a Cerb. Not on a drag strip and not round a circuit just in the real world. Yesterday I came to work in my Cerb, today in my XJR, same driver same roads so this is not bollox.
Maybe your Cerb isn't delivering what it should. Maybe if Jools or TVR Power look at it they may find something obvious. Maybe you are not being agressive enough with the throttle and the revs. In the Jag it is so easy with the autobox and the silence hiding the revs. In the Cerb you have to work for it.

[J_S_G]

Real world, I get point-to-point quicker in the Jag than in either of the TVRs. My Huddersfield -> Derby run that I do every week is about 80 miles of towns, fast countryside, winding lanes, dual carriageway, and motorway - pretty much everything. If we say that it takes "about an hour" (you really don't want to know! ), the Jag does it around 5 minutes quicker. Trundling along at 155 for prolonged distances in the Cerb/Tuscan was plain and simple tiring. In the Jag, you just dial the speed in on the cruise control, sit back, and relax at what's actually a comfortable cruising speed. Not that I'd know. Similarly, in the wet, it's great... gadgets for everything, and real confidence in what it'll do.

Oh, and if the XJR is quiet, can't you get a Paramount exhaust system?

[paulk]

joospeed said:

paulk said: do you know of any reason for this Joo? also the restricted inlets on the 4.2 limit the airflow available, and HP is all about airflow.

Can 4.5 inlets be fitted as a mod Joo? Also the cars you have mapped have they been ported as well, what I mean is the mods you carried out on my inlet manifolds a while back or will this not make a noticeable difference?
Plus would it still be worth doing when traction control becomes available if not for more power but as a proper control unit for the TCS?