4.2 tuning -lack off .......why?
Discussion
its an engine, only 300cc difference, but tell me gang why does no one provide add on tuning for the 4.2 ajp?
it was the original engine, seems to have been well received by the motoring press.
So why did TVR bring out a bigger engine that if you believe what many posters claim on these forums is an inferior dog of a block that can only be sorted by £xk to make it run 'correctly'?
was the AJP 4.5 (not the six) the real start of Tvr's decline?
it was the original engine, seems to have been well received by the motoring press.
So why did TVR bring out a bigger engine that if you believe what many posters claim on these forums is an inferior dog of a block that can only be sorted by £xk to make it run 'correctly'?
was the AJP 4.5 (not the six) the real start of Tvr's decline?
Edited by southendpier on Thursday 2nd August 00:55
The simple answer is that the 4.2 is already pretty well tuned and enjoys the better throttle response of the two (which makes it feel even livelier).
The 4.5 is badly mapped as standard - think of the first 30-40bhp gained from remapping as a repair rather than tuning. Power can then be gained with the shorter inlets which would ordinarily 'cost' oomph lower down the engine's range. You gain so much at low/medium throttle from the remap that you can 'afford' the notional loss/trade-off against the greater power at the top end.
"Bang per buck" adds up on a 4.5 because it's so wrong in the first place - you can tune a 4.2 but the cost-per-bhp is higher. It's the same amount of effort as a 4.5 but instead of chasing 10s of bhp, you're chasing a handful.
A remapped 4.5 has more grunt, drinks less gas and is much nicer to drive. Standard 4.5s don't like being below 3000rpm, remapped ones can be driven more like an ordinary car. All of that makes a strong case for remapping a 4.5. 4.2s just don't need that kind of attention.
No, the 4.5 wasn't the start of TVR's woes.
The 4.5 is badly mapped as standard - think of the first 30-40bhp gained from remapping as a repair rather than tuning. Power can then be gained with the shorter inlets which would ordinarily 'cost' oomph lower down the engine's range. You gain so much at low/medium throttle from the remap that you can 'afford' the notional loss/trade-off against the greater power at the top end.
"Bang per buck" adds up on a 4.5 because it's so wrong in the first place - you can tune a 4.2 but the cost-per-bhp is higher. It's the same amount of effort as a 4.5 but instead of chasing 10s of bhp, you're chasing a handful.
A remapped 4.5 has more grunt, drinks less gas and is much nicer to drive. Standard 4.5s don't like being below 3000rpm, remapped ones can be driven more like an ordinary car. All of that makes a strong case for remapping a 4.5. 4.2s just don't need that kind of attention.
No, the 4.5 wasn't the start of TVR's woes.
When you say a 4.5 is nicer to drive,in what respect?I find since ive had my 4.2 re-mapped it gets better the more i drive it.It idles at a steady 900rpm and now gives a near on smooth drive with hardly any jerkiness what so ever.Added to the fact the new slave and clutch MadMark fitted,im finding it very enjoyable in all kinds of traffic.
Originally the car was mapped by TVR Power.This along with the Tuscan race cams they fitted and a few other mods.But it was an absolute bitch to drive in town.It wasnt happy in slow traffic and was very jerky,to the point that after an hours driving,you had had enough.It was only happy if it you were giving throttle all the time.The flames from the exhaust were good,but the fuel consumption was dreadful.I left the car with Austecs last year for some work to be done.They swapped the chip that power fitted and put in a (generic)chip.I hope ive got that right.The car now is very much more usable,with only a slight drop in power to what was there before,and the sheets of flame have gone to be replaced by flashes.But its a much,much more enjoyable drive.
4.2's are VERY nice to drive, I used to have one and it was great. Smooth, punchy and very responsive.
I now have a remapped 4.5 and it is good too, pretty much the same as my 4.2 but with much more torque. The funny thing is it feels a little bit slower as the delivery is less dramatic. Never driven an unmapped 4.5 so I can't comment on that.
Just enjoy your 4.2, it reallly is a great car. If it isn't quick enough then fit some NOS and a progressive controller as it is probably the most cost effective performance mod IMHO.
I now have a remapped 4.5 and it is good too, pretty much the same as my 4.2 but with much more torque. The funny thing is it feels a little bit slower as the delivery is less dramatic. Never driven an unmapped 4.5 so I can't comment on that.
Just enjoy your 4.2, it reallly is a great car. If it isn't quick enough then fit some NOS and a progressive controller as it is probably the most cost effective performance mod IMHO.
ro_butler said:
4.2's are VERY nice to drive, I used to have one and it was great. Smooth, punchy and very responsive.
I now have a remapped 4.5 and it is good too, pretty much the same as my 4.2 but with much more torque. The funny thing is it feels a little bit slower as the delivery is less dramatic. Never driven an unmapped 4.5 so I can't comment on that.
Just enjoy your 4.2, it reallly is a great car. If it isn't quick enough then fit some NOS and a progressive controller as it is probably the most cost effective performance mod IMHO.
Yeah don't get me wrong I love my little 4.2 I now have a remapped 4.5 and it is good too, pretty much the same as my 4.2 but with much more torque. The funny thing is it feels a little bit slower as the delivery is less dramatic. Never driven an unmapped 4.5 so I can't comment on that.
Just enjoy your 4.2, it reallly is a great car. If it isn't quick enough then fit some NOS and a progressive controller as it is probably the most cost effective performance mod IMHO.
- mine's powerful enough and smooth - when you plant your foot the car flies, can't think why I'd want more power cause it'll break traction without too much effort, good fun as long as you don't think of the tyre cost. I guess perhaps it would be different if you were in competition. I just find it fascinating that TVR would release a car with such problematic characteristics. Weird.
The lads running 4.5s with 420+bhp with the big torque numbers must have to be very delicate with the right boot!
southendpier said:
I just find it fascinating that TVR would release a car with such problematic characteristics. Weird.
Really, most TVR's that left the factory were a mostly a pile of shite. So why does this suprise you?southendpier said:
The lads running 4.5s with 420+bhp with the big torque numbers must have to be very delicate with the right boot!
Depends, if you still have a lumpy sub 2000rmp then a kick at say 2200 and heaps or torque, then yes, but if the map is smooth and progressional, then not really...Mr F
I changed from standard 4.5 to short induction pipes and generic Performance re-map chip from Track car solutions.
I was always impressed with the standard 4.5 but did struggle to drive it around town and at 30mph in 4th. With the re-mapped chip I was staggered by the difference, now much easier to drive around town and smoother at low speeds in high gears. It's now as easy to drive as my jag and seems a lot quicker when you boot it!
Well pleased to say the least!
I was always impressed with the standard 4.5 but did struggle to drive it around town and at 30mph in 4th. With the re-mapped chip I was staggered by the difference, now much easier to drive around town and smoother at low speeds in high gears. It's now as easy to drive as my jag and seems a lot quicker when you boot it!
Well pleased to say the least!
I'm sure with cleaning out of the throttle casting/spindles butterflys, air box pulse plates, replacement manifolds (especially if you have the early smaller bore 4.2 ones), bigger bore exhausts (nearly all 4.2's). There will always be some room for tuning the 4.2. Whether you will ever get the bang for buck you can get for the 4.5 is open to debate (in both directions).
However there are always peeps where the bang/buck ratio is not so important
.
Question..
What gives the 4.2 the crisp throttle, is it the injectors down stream of the butterflys, is it the smaller air box or a combination of both (or something else)
However there are always peeps where the bang/buck ratio is not so important
.Question..
What gives the 4.2 the crisp throttle, is it the injectors down stream of the butterflys, is it the smaller air box or a combination of both (or something else)
4.2 roadtest
http://www.pistonheads.com/tvr/cerbera/default.asp...
4.5 roadtest
http://www.pistonheads.com/tvr/cerbera/ontheroad.h...
So a worked 4.5 gives about 420, what does a worked 4.2 give? Will it rev higher?
What's the difference in performance? And will one notice . . .
In the classifieds 4.2's are the cheaper ones. With the extra buck spend on a 4.5 a 4.2 could be tuned . . .
I love a crisp throttle respons. Is there THAT MUCH difference between both engine's, as tuned correctly?
Damn, the AJP8 is a helluvan engine.
http://www.pistonheads.com/tvr/cerbera/default.asp...
4.5 roadtest
http://www.pistonheads.com/tvr/cerbera/ontheroad.h...
So a worked 4.5 gives about 420, what does a worked 4.2 give? Will it rev higher?
What's the difference in performance? And will one notice . . .
In the classifieds 4.2's are the cheaper ones. With the extra buck spend on a 4.5 a 4.2 could be tuned . . .
I love a crisp throttle respons. Is there THAT MUCH difference between both engine's, as tuned correctly?
Damn, the AJP8 is a helluvan engine.
HarryW said:
Mars said:
My 4.5 is crispy enough for Walkers.
Is it remapped then , generally a standard 4.5 could be described as non linear rather than crisp in my limited experience.
I always found my 4.5 was fiery past 3K - for a modern EFI car it kind of behaved like a cammy, carburretored old-school hot rod. I sort of liked that, it demanded some effort to get the best out of it. Really though, looking back, it was a bit shit.
Funny thing is, though it was still the fastest thing I'd owned and I never got passed by anything on trackdays. At its worst it made 340-ish (with a dud coil pack and degrading HT lead), at its best I've no idea but clearly somewhere north of 350.
The FIRST thing I noticed when I picked my 4.5 up from Joolz was the driveability, not the extra 60-odd bhp. I can imagine 4.2 owners wondering what all the fuss is about with this remapping mullarkey as they will generally have the sort of power I initially had (more than adequate) but in a driveable car.
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