4.5 Autocar Road test
Discussion
Reading an old Autocar road test on the C8ERA 4.5 last night and the conclusion at the time was that it was not as fast or urgent as the 4.2, but was better put together, and more refined. Having had a 4.2 and wanting a 4.5 at some point i'm intrested in how they differ.
Autocar seemed to think the 4.2 was more rapid off the line and it wasn't until 150mph plus that the 4.5 had the advantage, as it was all top end power and max torque came in later than the 4.2
Anyone had one of each? What is your opinion?
Does the extra power make that much difference and is it worth the £5,000 extra??
Autocar seemed to think the 4.2 was more rapid off the line and it wasn't until 150mph plus that the 4.5 had the advantage, as it was all top end power and max torque came in later than the 4.2
Anyone had one of each? What is your opinion?
Does the extra power make that much difference and is it worth the £5,000 extra??
I have had 2 4.2 Cerbs and can confirm that the earliest Cerbs had a different higher spec engine to the later cars.
The early ones had high lift cams, which were reputed to break up and knacker the engine, which mine did, but made the engine massively quick.
The later cams made the 4.2 much more tractable, but I would guess at least 1/2 to 1 sec slower to 60.
Quite happy for this to be disputed by anybody that owned both intial run cerb (mine was engine 42 - inc race engines) and later car was 99/S.
By way of reference the cams have been mainly modified on the later cars and are termed 'whisper cams'.
In short early 4.2 on original cams fastest, then 4.5 then later 4.2 in my humble opinion.
Bennno
bennno said:
The early ones had high lift cams, which were reputed to break up and knacker the engine, which mine did, but made the engine massively quick.
The later cams made the 4.2 much more tractable, but I would guess at least 1/2 to 1 sec slower to 60.
Bennno
Joolz,
I know this to be true, did they replace the original cams due to lobe wear?
I remeber you saying Piper cams were going to do some different cams on an engine Raven were rebuilding, is this right and how far have they got?
Is it possible to get hold of the early cams still, and do they really make that much difference anyway?
Questions questions
Cheers
Rob.
Is it possible to get hold of the early cams still, and do they really make that much difference anyway?
Questions questions
Cheers
Rob.
As below they were significantly more peaky, which gave the car a burst of speed from about 3.5K onwards.
the cams were very noisy on the car and made it sound like a 10yr old fiesta, hence the change.
The new ones were better for everyday rd use.
Bennno
I'm not sure anyone is/was saying that the 4.5 is slower than the early 4.2s, just that the additional performance from the 4.5 doesn't come into play unit over 150mph.
Maf said: So given the 4.5's aren't as quick as the original 4.2 whose figures stunned the world, would they still better a Tuscan S? Red Rose to tip the balance?
I suspect that a regular 4.5 and a Tuscan S are very, very close in performance. The RR might just tip it as you suggest, but not to the extent that any one would be able to detect it: the difference between individual cars is probably much greater than any different the RR pack adds.
Jeremy
(and a fast-enough-thankyou 4.5)
>> Edited by jeremyc on Thursday 14th November 23:04
Joolz... please debunk the 4.2 fastest myth again! Basically, the early cars had inefficient rear backboxes and exhaust port design that cost quite a bit of power.
The whisper cams have similar lift, they just have proper ramps to take up the clearances and reduce valvetrain stress- this doesn't necessarily affect the duration or lift.
The Red Rose 4.5 mods added 50bhp to my car. I'd say that was more than the average variance between cars and is certainly noticeable side by side a standard car!
Given that 4.2's have around the quoted BHP, the first ones would hardly have been more powerful, would they? TVR are hardly renowned for UNDERSTATING the power after all! The rise in torque around 4k just makes it FEEL faster, even though performance using the higher revs is identical.
My 2p anyway
danny
The whisper cams have similar lift, they just have proper ramps to take up the clearances and reduce valvetrain stress- this doesn't necessarily affect the duration or lift.
The Red Rose 4.5 mods added 50bhp to my car. I'd say that was more than the average variance between cars and is certainly noticeable side by side a standard car!
Given that 4.2's have around the quoted BHP, the first ones would hardly have been more powerful, would they? TVR are hardly renowned for UNDERSTATING the power after all! The rise in torque around 4k just makes it FEEL faster, even though performance using the higher revs is identical.
My 2p anyway
danny
in reference to the article in sprint though,its a bit of a bitch to lay out thirty grand(ish)on a new 4.5 only to find out its a bit slower than your old 4.2. i know he said his new car is better built etc but its still disapointing.
how long can i expect my original hard cams to last,cars on 26k?
how long can i expect my original hard cams to last,cars on 26k?
ro_butler said:
bennno said:
The early ones had high lift cams, which were reputed to break up and knacker the engine, which mine did, but made the engine massively quick.
The later cams made the 4.2 much more tractable, but I would guess at least 1/2 to 1 sec slower to 60.
Bennno
Joolz,
I know this to be true, did they replace the original cams due to lobe wear?
I remeber you saying Piper cams were going to do some different cams on an engine Raven were rebuilding, is this right and how far have they got?
Is it possible to get hold of the early cams still, and do they really make that much difference anyway?
Questions questions
Cheers
Rob.
there's no power output difference between the early and late cams are far as I can tell from many mant rolling road sessions, and if there are any small differences I've not spotted it's much more likely to be down to reduced compression ratio and tame ignition mapping anyway.
Piper have done some cams for me, but engine isn't being built at Raven.
dannylt said: Joolz... please debunk the 4.2 fastest myth again! Basically, the early cars had inefficient rear backboxes and exhaust port design that cost quite a bit of power.
The whisper cams have similar lift, they just have proper ramps to take up the clearances and reduce valvetrain stress- this doesn't necessarily affect the duration or lift.
The Red Rose 4.5 mods added 50bhp to my car. I'd say that was more than the average variance between cars and is certainly noticeable side by side a standard car!
Given that 4.2's have around the quoted BHP, the first ones would hardly have been more powerful, would they? TVR are hardly renowned for UNDERSTATING the power after all! The rise in torque around 4k just makes it FEEL faster, even though performance using the higher revs is identical.
My 2p anyway
danny
All this is true as far as I can work out ..
dannylt said:
The Red Rose 4.5 mods added 50bhp to my car
danny
Danny you got any print outs for peak power output etc. from either a rolling road or when your engine was bench tested. I've spoken with several people at the factory inc. Baldrick and they are giving the figure of a max 20 BHP more and 10lb ft, the recent press articles in EVO, AutoCar, CAR etc. all quote the same figures (no doubt given to them in the same press release) Would be interested to see if some sort of documented proof of what the eingine mods really offer.
I know that the response of the engine etc. are all quicker so the car responds quicker etc. not questioning that just interested in what the figures state - though the sports exhaust and green filters might help with the performance a tad !!
Anyhow if you have anything any chance you can post it up here or bring with you the next time you come to take the Tuscan out
Cheers
Darren
d_drinks said:
dannylt said:
The Red Rose 4.5 mods added 50bhp to my car
danny
Danny you got any print outs for peak power output etc. from either a rolling road or when your engine was bench tested. I've spoken with several people at the factory inc. Baldrick and they are giving the figure of a max 20 BHP more and 10lb ft, the recent press articles in EVO, AutoCar, CAR etc. all quote the same figures (no doubt given to them in the same press release) Would be interested to see if some sort of documented proof of what the eingine mods really offer.
I know that the response of the engine etc. are all quicker so the car responds quicker etc. not questioning that just interested in what the figures state - though the sports exhaust and green filters might help with the performance a tad !!
Anyhow if you have anything any chance you can post it up here or bring with you the next time you come to take the Tuscan out
Cheers
Darren
The majority of sports exhausts for cerbies are generally acknowledged to reduce mid range torque very slightly but they weigh less than the std box so it's swings and roundabouts here! The early back boxes (of which there's probably none left by now) were 90 degree perforated pipework inside rather than nice flowing bends, they sapped about 30 bhp according to a factory suorce.
early manifolds are small bore and produce a pronounced step against the exhaust flow, early cars are fundamentally flawed and definately NOT faster in my experience. Incidently early rear box high flow mod was to take all the innards out so you have an empty chamber .. sound glorious
Danny's cerbie made bang on 350 bhp before conversion and 398 after conversion, corrected results on the same rollers.
Joolz
davidd said: Yes I have an early 4.2 (number 30 something), sounds very bad, goes very fast
DeCatting seems to be helping the sound a bit.
Danny, if what you say is true about the back box should I be looking to replace mine?
Joolz, any news on that piper cam engine?
D.
the engine is back from the builders but won't be in car for another few weeks I guess.
Fastest 4.2 I ever drove was C4TVR .. factory engine rebuild with hi compression pistons, my ported inlets and k+n filters , made bang on 350 bhp (like danny's 4.5, on the same rollers) but also made the highest torque figure ever recorded for a 4.2 cerbie.. something like 340lb.ft. over a wide rev range and that's what gives you the acceleration. I've seen a 4.5 cerbie at 298 lb.ft .. however that is exceptionally low and most 4.5 cerbies make more than 4.2 versions (about 330lb average) but also the spread is better hence they are slightly quicker on average.
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