The Suitably Re-Engineered Chimaera Club
Discussion
QBee said:
OleVix said:
Im joining the club with a rebuilt 4.6 tophats, big valve stage3, high compression engine. I'll try using a 500 chip to fuel it. Does the 500 and 400 share the same injectors? same 14cux on 400 and 500?
500 chip is different. Injectors are the same, but tend to max out at 290 bhp ish......but you could be ok at that. If it runs lean above 4500 rpm, bigger injectors and AFM cost a few hundred pounds.
If you change the injectors or AFM you will need to remap the ECU - several hundred quid, plus bringing the car to the UK. So try both chips first I suggest.
But given your location, if neither chip is satisfactory, I suggest you change to a mappable after market ECU if you have a local mapper.
It will.....I had that done to mine, but when Mark Adams remapped it (at 300 bhp, loads of mods), the first thing he did was replace the higher pressure one with a standard one. Which suggests that you have sufficient fuel pressure.
I am not sure what mod corrected mine, but it went lean at about 4500 rpm, and I was advised to get bigger injectors and a bigger AFM. I run a standard fuel pump and standard regulator. Somewhere in all this, including the remap, my lean running issues were resolved and the car runs fine now.
I am not sure what mod corrected mine, but it went lean at about 4500 rpm, and I was advised to get bigger injectors and a bigger AFM. I run a standard fuel pump and standard regulator. Somewhere in all this, including the remap, my lean running issues were resolved and the car runs fine now.
Feeling a bit low today. The car has been undergoing its first mod to push me towards the SRECC but has hit snags.
Had the car booked in to undergo full de-catting on the exhaust and have a non reversal cone fitted in the y piece to try and avoid the "dustbin" effect.
Unfortunately 4 of the manifold bolts sheared off meaning that they had to be drilled out. That was bad enough but because the bolts were at the back they couldn't get access so have had to lift the engine as well!!
Really wasn't prepared for the extra hassle and delay. The only good news is that when they lifted the engine they confirmed the chassis and top rails were all in pretty good nick with only a little surface rust.
Just hope the sound and extra few horses are going to put the smile back on my face when it does come back.
Had the car booked in to undergo full de-catting on the exhaust and have a non reversal cone fitted in the y piece to try and avoid the "dustbin" effect.
Unfortunately 4 of the manifold bolts sheared off meaning that they had to be drilled out. That was bad enough but because the bolts were at the back they couldn't get access so have had to lift the engine as well!!
Really wasn't prepared for the extra hassle and delay. The only good news is that when they lifted the engine they confirmed the chassis and top rails were all in pretty good nick with only a little surface rust.
Just hope the sound and extra few horses are going to put the smile back on my face when it does come back.
QBee said:
It will.....I had that done to mine, but when Mark Adams remapped it (at 300 bhp, loads of mods), the first thing he did was replace the higher pressure one with a standard one. Which suggests that you have sufficient fuel pressure.
Well mine was dangerously lean across the board at some point including idle (confirmed on the rollers) so after having checked everything else, out came the FPR and into the vice...phazed said:
Bad luck!
I've never heard a dustbin with a cone fitted
The idea was to retain the standard y piece shape to keep all the geometry and fit an internal cone (funnel) similar in shape to the one siliconekid pictured. Seemed like a simple idea to obtain the full de-cat effect until I can afford the piece of art from Clive F.I've never heard a dustbin with a cone fitted
I'll try and post a sound bite when I get it back.
OleVix said:
QBee said:
OleVix said:
Im joining the club with a rebuilt 4.6 tophats, big valve stage3, high compression engine. I'll try using a 500 chip to fuel it. Does the 500 and 400 share the same injectors? same 14cux on 400 and 500?
500 chip is different. Injectors are the same, but tend to max out at 290 bhp ish......but you could be ok at that. If it runs lean above 4500 rpm, bigger injectors and AFM cost a few hundred pounds.
If you change the injectors or AFM you will need to remap the ECU - several hundred quid, plus bringing the car to the UK. So try both chips first I suggest.
But given your location, if neither chip is satisfactory, I suggest you change to a mappable after market ECU if you have a local mapper.
Over the years I have done a great deal of research into this matter, in the form of reading and experimentation. I am also privileged to have access to very thorough research on this subject done by major motor manufacturers and component suppliers (e.g. Bosch, Land Rover, etc). Although I cannot pass it on directly, I can at least give you the distilled essence.
The standard RV8 pump is indeed rated at 3.0 Bar, although it is only operated at 2.5 Bar so there is a useful margin available. There are a number of effects of increasing the fuel pressure which must be considered, and the results for the pump and injectors are quite different.
Firstly, increasing the fuel pressure will obviously put more strain on the pump. The flow of fuel through the pump provides it's cooling, and flow drops generally in a non-linear manner with increasing pressure (usually logarithmic).
In general, increasing pressure will improve the atomisation of the injectors for pintle and type II/III designs but not for the Lucas disc type. All fuel injectors are for a specific operating pressure, or pressure range. The effects of increasing the pressure are heavily dependant on the design.
For the Lucas disc design, increasing pressure will increase the flow up to a point. The injector has an upper and lower disc. The lower disc has a hole in the centre (the metering orifice), and the upper disc is lifted by the electro-magnetic solenoid to allow fuel to flow.
It is quite obvious that the higher the pressure, the harder it is to lift the upper disc to allow fuel to flow. This results in a much longer and more unstable opening time for the injector. After 3.3 Bar the fuel flow will actually start to decrease and become more unstable as the electro-magnet struggles to overcome the force of the fuel pressure closing it.
This also requires that the battery voltage compensations in the ECU are adjusted accordingly, since they are dependant on operating pressure.
Additionally the Lucas injector does not produce an atomised spray through the metering orifice. This function is provided by the plastic diffuser underneath, which is supposed to break up the jet into droplets. Quite often there is no atomisation at all.
Ever more stringent emissions legislation has driven advances in fuel injector design. Improvements in manufacturing technology have produced some far more effective fuel injectors, with the aim of producing more efficient combustion. Some of the best designs are the Bosch Type II and Type III versions.
Fuel enters the combustion process by two methods for this type of manifold injection system. Firstly there is fuel which is pulled from the manifold walls by the air stream entering the combustion chamber when the inlet valve is open. This fuel is deposited on the manifold walls by the injectors when air is not flowing in the inlet tract. During this time the fuel deposited will evaporate in a warm engine, so the smaller the droplets are the better and faster they evaporate. Some fuel droplets remain in suspension in the air in the inlet tract, and again the smaller they are the better.
During recent testing on standard TVR 5.0 Litre engines, the injectors picked up 8 lb/ft of torque everywhere over a hand picked flow-matched set of brand new Lucas originals. This has been accurately and scientifically tested dozens of times, and is always the case.
Interestingly the improved torque required 2-3 Degrees less ignition advance, denoting improved combustion speed and efficiency. If you simply put in an injector with better atomisation, you will indeed see a drop in power because the ignition timing is now too far advanced for the reasons given above.
When mapping a car and selecting injector sizes, the injectors should run no more than an 80% duty cycle at any point in the map. Obviously the time available for injection decreases with rising RPM. This limit is necessary in order to allow for transient fuelling (sudden throttle opening), and proper response when the engine is cold amongst other factors.
Whilst it is true that the standard Lucas injectors can be operated on motors producing 350BHP, it takes them to 100% opening at pressures well outside the operating envelope. I have asked this before and have never been given an answer - can anyone please tell me what the duty cycle was THEY MEASURED on one of these 350BHP cars? I think not.
Hi all, I will be carrying out some suitable re-engineering this weekend by fitting act trumpets, elbow and thermal gasket. At what point should I go to Surrey rolling road? As far as I know it has never been run and my thinking is it could do with a set up? Also I'd like to know the health of my engine/cam? Engineer1949 has offered to inspect the cam and bottom shells at next service but thats not til oct or should I leave rr until after that I know the health of engine/cam in case I need a new cam then set up. Do I need Rr at this point or just do timing etc? Should I get it remapped at the same time?Sorry for the newbie type questions.
blitzracing said:
OleVix said:
QBee said:
OleVix said:
Im joining the club with a rebuilt 4.6 tophats, big valve stage3, high compression engine. I'll try using a 500 chip to fuel it. Does the 500 and 400 share the same injectors? same 14cux on 400 and 500?
500 chip is different. Injectors are the same, but tend to max out at 290 bhp ish......but you could be ok at that. If it runs lean above 4500 rpm, bigger injectors and AFM cost a few hundred pounds.
If you change the injectors or AFM you will need to remap the ECU - several hundred quid, plus bringing the car to the UK. So try both chips first I suggest.
But given your location, if neither chip is satisfactory, I suggest you change to a mappable after market ECU if you have a local mapper.
/
When mapping a car and selecting injector sizes, the injectors should run no more than an 80% duty cycle at any point in the map. Obviously the time available for injection decreases with rising RPM. This limit is necessary in order to allow for transient fuelling (sudden throttle opening), and proper response when the engine is cold amongst other factors.
Whilst it is true that the standard Lucas injectors can be operated on motors producing 350BHP, it takes them to 100% opening at pressures well outside the operating envelope. I have asked this before and have never been given an answer - can anyone please tell me what the duty cycle was THEY MEASURED on one of these 350BHP cars? I think not.
l6rth said:
Hi all, I will be carrying out some suitable re-engineering this weekend by fitting act trumpets, elbow and thermal gasket. At what point should I go to Surrey rolling road? As far as I know it has never been run and my thinking is it could do with a set up? Also I'd like to know the health of my engine/cam? Engineer1949 has offered to inspect the cam and bottom shells at next service but thats not til oct or should I leave rr until after that I know the health of engine/cam in case I need a new cam then set up. Do I need Rr at this point or just do timing etc? Should I get it remapped at the same time?Sorry for the newbie type questions.
Would appreciate answers to my newbie questions.l6rth said:
l6rth said:
Hi all, I will be carrying out some suitable re-engineering this weekend by fitting act trumpets, elbow and thermal gasket. At what point should I go to Surrey rolling road? As far as I know it has never been run and my thinking is it could do with a set up? Also I'd like to know the health of my engine/cam? Engineer1949 has offered to inspect the cam and bottom shells at next service but thats not til oct or should I leave rr until after that I know the health of engine/cam in case I need a new cam then set up. Do I need Rr at this point or just do timing etc? Should I get it remapped at the same time?Sorry for the newbie type questions.
Would appreciate answers to my newbie questions.I RR'd mine shortly after purchase, simple power runs, to establish what she was pushing out. This gave me a base case for future modifications/health checks. I've repeated this after each engine mod
If you have the standard 14CUX ECU then mapping (I believe) is not an option. You can get a different chip put in but with the mods you are carrying out I don't think you'd gain anything, other than a hole in the bank account.
ChilliWhizz said:
l6rth said:
l6rth said:
Hi all, I will be carrying out some suitable re-engineering this weekend by fitting act trumpets, elbow and thermal gasket. At what point should I go to Surrey rolling road? As far as I know it has never been run and my thinking is it could do with a set up? Also I'd like to know the health of my engine/cam? Engineer1949 has offered to inspect the cam and bottom shells at next service but thats not til oct or should I leave rr until after that I know the health of engine/cam in case I need a new cam then set up. Do I need Rr at this point or just do timing etc? Should I get it remapped at the same time?Sorry for the newbie type questions.
Would appreciate answers to my newbie questions.I RR'd mine shortly after purchase, simple power runs, to establish what she was pushing out. This gave me a base case for future modifications/health checks. I've repeated this after each engine mod
If you have the standard 14CUX ECU then mapping (I believe) is not an option. You can get a different chip put in but with the mods you are carrying out I don't think you'd gain anything, other than a hole in the bank account.
Nothing you have listed shouts "needs a remap" to me. Remap is required for major changes.
The only 14CUX remapper I know of is Mark Adams, who lives in the Welsh Borders. Jools at Chesterfield as been working on this, but I don't know how far he as got.
Take it to Mat Smith. Downham Market. 01366 386004. Just off the A10. Top bloke, 20 years TVR experience. A good inspection and fettle will cost you less than £100. And if the car is trying to kill you, or just handlng badly, Mat can do a full geo for you for a similar price. Tell him I recommended you to him.
The best bang for buck with a newly acquired Chim is getting the car checked over and the suspension/handling sorted first.
Email me if you want a phone chat. happy to help.
l6rth said:
Thanks Chilli, I suppose I will just get the cam checked in the autumn to see if it needs replacing. Is there anything else I should get checked? I.e the timing?
Ignition timing check/adjust is part of the 6K service schedule. If you don't have the documentation regarding service history or recent history is a bit sketchy I'd be inclined to get a full service carried out regardless.QBee's advice is sound, I've had quite a few things attended to by Mat, he's a top bloke, very knowledgeable and extremely helpful. And he's not too shabby on track either
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