Charge Cooler Retro fit?
Discussion
A chargecooler does not give me more power on an SE. It allows me to hold max boost longer. You know like on the intial boost spike before it settles downs. It will allow you to hold it a lot longer on the boost spike maybe 30-40 sec or longer. Not sure how it would work on mechanical injection and it's sensors. I suppose it will allow you to boost it a few more lbs. So it may help little in your appilcation as the boost is dialed down to 9.5 and you could possibly take it 12.
Calvin
Calvin
My thinking was that as it cools the incoming air it would therefore increase its density making it possible to force more air fuel mixture into each cylinder per combustion. I woundered if maybe this would have the effect of a noticable gain in torque over a noticale gain in power. I was also thinking of fitting a BOV to allow the turbo to better respond in feed the slightly denser charge to the cylinder.
My overall hope was to increase overall drivability.
Note the engine in the UK spec is not injected the turbo force feeds through two twin choke Delorto carbs thus making it relatively simple to change mixture or even jets to achieve max performance on a rolling road.
Any further toughts?
My overall hope was to increase overall drivability.
Note the engine in the UK spec is not injected the turbo force feeds through two twin choke Delorto carbs thus making it relatively simple to change mixture or even jets to achieve max performance on a rolling road.
Any further toughts?
Well first of all the BOV discussed here and the turbo list that we use in EFI cars would not work in your car as you do not have a MAP sensor and other things associated with the EFI. True, the chargecooler will allow you to have a higher boost with out knocking but it is more complicated than adding a cooler and turning up the boost on a carb car. It is much harder to do in your carb equiped/non computer aided ignition car than in an EFI/engine management controlled car as it constantly monitors and adjusts. All we do is change the chip or remap the one we have. You must tinker with all sorts of things for hours to do what we do in few minutes, I would think to make it work right it would take a lot of time. I will defer to the carb people to chime in on this one.
Calvin
Calvin
I'm with Calvin on the charge cooler business. You need an ECU controlled engine to take appreciable advantage of the colder air that would be entering the engine. That is the real beauty of the EUC. It senses several operating conditions, manifold air temperature (MAT) being one of them, and dynamically adjusts the amount of fuel going to the engine. It does this constantly, and it does it several time a second. Without the ability to do this dynamically, you are guessing at how much more fuel to give the engine at any given moment, and chances are you’re going to be wrong most of the time. And even if you get it somewhat right, it will probably be right for only a very narrow range of operating conditions. Now you can still go ahead and add the charge cooler and you will probably get some benefit, but I don’t suspect that it will be anything like the 50 or so HP that might be expected out of an ECU controlled engine. I think that is what Lotus claimed they got when they deployed the charge cooled engine – 235>285 HP.
lotusguy said:
Does anyone know what power would be gained by fitting a charge cooler to a stock carb fed turbo HC engine, obviously using an electric pump etc.
Adding a charge cooler to a carb'd car is the wrong way to go about getting more power and torque. This is because the intensive work involved will not have anywhere near the cost/benefit of some other mods. You will find the car difficult to tune and won't appreciably improve the performance at all, simply because the engine is not set-up to use it. And, charge cooling by itself will not increase boost, it merely allows you to perform other changes that do increase the boost. Modifications to the wastegate and carbs will also be necessary. It will give you the "Mine's bigger than Yours" bragging rights, but you'll not be happy with the results.
And, as you have an anologue, rather than an elctronically controlled engine, you cannot make dynamic changes to it. This means that you must decide at the outset between 'Grunt or Go'. You must set up the car for optimum performance either for low end torque (Grunt) or high end power (GO). It's all a trade off.
That having been said, you can probably find a middle ground which will make your car more power while maintaining it's driveability.
The first step is to first ensure that your engine is in good order. It makes no sense to modify a tired engine only to have it blow up from the increased power in a couple thousand miles.
First up is a carburettor rebuild/tuneup. The DellOrto DHLA 45M is a pressurised carb. This means that it takes much more abuse than a passiive non-pressurised one. Buy a rebuild kit to replace the urethane gaskets, accel. pump diaphram and spring and all the rubber 'O' rings. Fit a new needle valve and seat and weigh the carb floats. These can develop leaks allowing gas to enter making them heavier. If they weigh more than 8 grams, it's time to swap them out.
Then have a leakdown test performed on the engine. This will give you an idea of the integrity of your valves and rings. Note the results and take the appropriate action.
Next, a change in your cam profiles is where the results you are seeking really lie. You can opt for a custom grind, or opt for a more aggressive off the shelf profile. These vary from the mildly higher lift 104 Cam (0.412" vs 0.378" stock) to the very agressive, but not very streetable DS2 Cam (0.456" lift). The important thing is to mimic or maintain the stock duration as the valve overlap on the 907 head is very limited due the the interferrence nature of it. I have a 104 Cam in my car and gave away a mild amount of low-end torque for more power higher in the power band. My car comes 'On Cam' at 3,000RPM as opposed to the stock 2,600 RPM, but stays on cam through 6,800RPM as opposed to the 5,900RPM for the stock cam.
It's also a good idea to have your valves done at this time with a 3 angle grind and new valve guides at a minimum. While you probably don't need seats, your springs will be worn and tired. Remember that while the cam opens the valves, it's the springs which close them smartly and tightly. The springs are only really good for 40k mi., after that, they lose their strngth and don't work as they should. If your are close to this, replace them. You'll also have to replace the head gasket at this time.
The next step, and it's a big one, is to have your head ported, as long as it's out. The intake/exhaust ports on the 907 head are about 1/8" to 1/4" smaller in diameter than the intake/exhaust manifold runners. This is a serious airflow restriction, which, once removed will give the engine an entirely new personality. Forego polishing as the new school of thought is that this disrupts airflow to the point that little or no benefit is derived. FIA teams have discovered this through fluid dynamic computer testing and no longer use it.
Next, rebuild your turbo to ensure that the bearing and seals are in good order. I had mine over-bored to accept a roller bearing which is much more robust and limits the spool-up lag. And have your wastegate adjusted to 0.758 Bar or 11lbs. boost. This is done via either the diaphram adjusting screw (if so equipped) or shimming the diaphram spring. A competent shop can perform this.
You already have a BOV installed as standard equipment. Lotus calls this a 'Dump Valve' (Lotus Part #C910E0928F) it lives under your fuel pressure regulator, so no worries there. But, after you make these changes, you will also probably want to increase the size of your idle jets and possibly the mains. This is best done on a dynamometer or rolling road, but a safe increase is to take the stock 0.52's and add 0.62's to the idle circuit. I left the mains alone on mine, but may experiment with them next year. I hope that you find these tips useful, I did them all on my '85 carb'd car this past summer, and I can now run with the SE's (albeit breathing a little heavier) and I did not add the weight and complexity of chargecooling. Chargecooling is not the first thing you should do, it's the very last thing. Hope this helps...Jim '85TE
>> Edited by lotusguy on Tuesday 10th December 18:41
>> Edited by lotusguy on Tuesday 10th December 20:36
I would consider adding "in-cylinder" charge cooling ie a water spray (one of the guys on the lotusespritworld (kato's website) has done this. I have done this on a jap turbo car (celica) and it does prevent detonation with increased boost.... a little old tech these days, but then again, so is a turbo/carb combo. Water injection/spray was commonly used to achieve higher boost pressure in pre ECU days..
The SE has to go im afraid. I may try an S4s in a couple of years but, I have had my experience of an SE time to move on. Although I must say I still feel there must be some advantage to having a charge cooler without an ECM as Lotus themselves tried to gain a form of chargecooling without the extra cost of afull bvlown charge cooler on the carb turbo by casting fins into the alloy intake trunking. Also the well known problems associated with having such a hot engine in a confined mid engine layout has constantly been looked at by Lotus throughout the Esprit's development.
The S4s is not really that different than my SE. Some what similar HP. Oh the S4s is a better car than mine. I have not hat a problem with a hot engine in my engine bay. Cold A/C on hot 100F day and the coolant temp is 90C with it idling in traffic. normally it is 82C. The chargecooler is usually ice cold to the touch, not what one would expect when they talk about it being ambiment temp. if it feels like body temp or warmer it is not working right. I don't know when I will bump up to a V8, but I will miss the SE a lot when the time comes.
Calvin
Calvin
Calvin
Calvin
No I am not complaining about my SE either an excellent machine. I just fancy a change, thats why I feel in a couple of years time I may try an S4s, I always seem to be pulled back to the Esprit when I try other cars out for a while. The S4s has the walnut dash which I particularly like, tail mounted spoiler which I prefer to the S4's mid mounted spoiler fanastic looking alloys PAS etc and performance that is barely usable in the UK just like the SE.
I have been keeping an eye out for a S4s/97 V8 also. Not real serious but if the right deal came around I might go for it. I can use what performance the Esprit has where I live. We do not have unmanned speed cameras, all speeding violations are a one on one situtation with a traffic control officer in person.
Calvin
Calvin
lotusguy said:
Does anyone know what power would be gained by fitting a charge cooler to a stock carb fed turbo HC engine, obviously using an electric pump etc.
I'd consider installing a simple water injection setup (homemade working off a pressure activated pneumatic switch) on the grounds of cost & simplicity. Inject a small amount of water into the intake via a fine nozzle. Your car will think it's being driven on a cold misty morning and in a way it will be! I have done this on another vehicle, injecting before the turbo's without any problems. The water is vapourised as it travels through the compressor and in the inlet tract.
Hey boosted:
I experienced exactly what you are saying just today. I made the mistake of diving my SE to work today. The weatherman said it would be cloudy but no rain. So, I thought it would be OK to drive. WRONG. The day started out OK with about 75% cloud cover, but by 10:00 a.m. it was misting and the fog was so thick you could cut it with a knife. Anyway, when I went out for lunch I notice right away that she had more pep than normal. I mean it was very noticeable. And I have never noticed this phenomenon in any other car that I have ever owned. And I have had at least 50 cars in my lifetime. It must be the sophisticated engine management systems in these SEs. My guess is that the ECU is able to adjust in ways that a carbed vehicle is just not able to do. I'm a believer.
Do you know of anyone that makes a water injection kit? I might be interested in trying it, that is, if I can fit it without hacking things up. Might be a worthwhile thing to have on race day.
A footnote to this. I remember when I was a kid (this was about 40 years ago) I had an very wise and mechanical uncle that put one of these things on a "Rambler", of all things. I remember him raving about how well it worked. He claimed that it improved the mileage, and power, and even cleaned the carbon from the combustion chamber. He claimed that this particular car was badly carboned up, and had a terrible pinging problem, but after a couple of months of operation, the pinging stopped. I also remember him saying that he could see the top of the pistons and they looked clean as a whistle. I’m not saying that it is gospel truth. It’s just something to think about.
Cheers!
Walt, '91 SE
I experienced exactly what you are saying just today. I made the mistake of diving my SE to work today. The weatherman said it would be cloudy but no rain. So, I thought it would be OK to drive. WRONG. The day started out OK with about 75% cloud cover, but by 10:00 a.m. it was misting and the fog was so thick you could cut it with a knife. Anyway, when I went out for lunch I notice right away that she had more pep than normal. I mean it was very noticeable. And I have never noticed this phenomenon in any other car that I have ever owned. And I have had at least 50 cars in my lifetime. It must be the sophisticated engine management systems in these SEs. My guess is that the ECU is able to adjust in ways that a carbed vehicle is just not able to do. I'm a believer.
Do you know of anyone that makes a water injection kit? I might be interested in trying it, that is, if I can fit it without hacking things up. Might be a worthwhile thing to have on race day.
A footnote to this. I remember when I was a kid (this was about 40 years ago) I had an very wise and mechanical uncle that put one of these things on a "Rambler", of all things. I remember him raving about how well it worked. He claimed that it improved the mileage, and power, and even cleaned the carbon from the combustion chamber. He claimed that this particular car was badly carboned up, and had a terrible pinging problem, but after a couple of months of operation, the pinging stopped. I also remember him saying that he could see the top of the pistons and they looked clean as a whistle. I’m not saying that it is gospel truth. It’s just something to think about.
Cheers!
Walt, '91 SE
wcdeane said: Hey boosted:
I experienced exactly what you are saying just today. I made the mistake of diving my SE to work today. The weatherman said it would be cloudy but no rain. So, I thought it would be OK to drive. WRONG. The day started out OK with about 75% cloud cover, but by 10:00 a.m. it was misting and the fog was so thick you could cut it with a knife. Anyway, when I went out for lunch I notice right away that she had more pep than normal. I mean it was very noticeable. And I have never noticed this phenomenon in any other car that I have ever owned. And I have had at least 50 cars in my lifetime. It must be the sophisticated engine management systems in these SEs. My guess is that the ECU is able to adjust in ways that a carbed vehicle is just not able to do. I'm a believer.
Do you know of anyone that makes a water injection kit? I might be interested in trying it, that is, if I can fit it without hacking things up. Might be a worthwhile thing to have on race day.
A footnote to this. I remember when I was a kid (this was about 40 years ago) I had an very wise and mechanical uncle that put one of these things on a "Rambler", of all things. I remember him raving about how well it worked. He claimed that it improved the mileage, and power, and even cleaned the carbon from the combustion chamber. He claimed that this particular car was badly carboned up, and had a terrible pinging problem, but after a couple of months of operation, the pinging stopped. I also remember him saying that he could see the top of the pistons and they looked clean as a whistle. I’m not saying that it is gospel truth. It’s just something to think about.
Cheers!
Walt, '91 SE
Walt,
Water injection is not a new innovation by any means. It was developed in the 1920's to allow for higher compression and therefore more powerful aircraft engines.
How it works is simple. Water is a very good heat conductor, in other words it can absorb relatively large amounts of heat as compared to it's volume or mass. Consequently, when you inject small amounts of 'atomized' water into the combustion chamber along with the charge, it absorbs much of the heat of the charge (fuel/air) dropping it well below it's combustion point. This allows the piston to compress the charge even more before it ignites. Further, because the charge is cooler, it allows for better 'flame travel' from the spark. This means that more energy can be derived from the fuel, making more power.
Without this cooling effect, higher compression engines would reach the ignition point of the charge before compression was complete, and spontaneously ignite before the spark was introduced. This is known as pre-ignition, knock or pinging and is very bad as the mechanical cycle of the engine is not ready for this combustion to take place and so excess stress is put on internal parts leading to premature failure of the engine or it's various components.
Introducing the 'atomized' water into the compressed air stream will have a similar effect, but will not be as effective as injection directly into the cylinder. It can have a 'cleaning or decarbonizing' effect as it allows for more complete combustion, lessening the buildup of carbon in the system.
But the effect you experienced today was not associated with the effects of water injection at all, except that 'stormy' air is usually cooler and so more dense. This in turn more completely combusts the fuel mixture so more power is released. This phenomenon was present in all your previous cars, but as you say, you didn't notice it. As far as the sophistication of the SE Engine Management system, it was for it's day, but today, the VW beetle and Mini Cooper have more sophisticated systems as do many run of the mill econoboxes.
Again, water injection is no cure all and has many undesireable effects and inconveniences associated with it. Also, unless you dial in more boost or fuel, it really doesn't make that much extra power, not enough to notice. But, it will allow you to dial in this extra boost or fuel without reaching a pre-ignition point...Jim '85TE
It's a very complex system, with several components to break, leak etc. and delivers no more power than a different cam profile, which is easier, cheaper and more reliable...Jim '85TE
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