|
Timed Duty : Direct Port Injection
I am considering the Direct Port injection on the next setup build although during some research this came to my mind and I just could not stop thinking......
Pre-throttle body Injection : As soon as target boost value is achieved the pump progressively switches on and pressurize the check valves. Above the check valve pressure value the nozzles begin to mist the mixture progressively. The plenum delivers the mixture to the cylinders accordingly until throttle is closed Direct-Port Injection : Repeat : As soon as target boost value is achieved the pump progressively switches on and pressurize the check valves. Above the check valve pressure value the nozzles begin to mist the mixture progressively. All Four nozzles (in case 4cyl) begin misting the mixture into the port simultaneously until I say --- WHAT! the hell am I doing???? We all know that fuel injection happens in TIME and DUTY. Injecting all injectors at once will actually inject ALL THE TIME at different duty at a closed valve while the cylinders could be doing three different stokes rather than the intake cycle! The only way to properly design direct port injection is to have a timed-duty setup that injects the mixture in time of that intake event on that particular cylinder at different duty cycles. This could be done by the use of fast acting relays and line pressure always ready to inject. Would be more worth using a pump and injectors rated safe for methanol and connect them directly to ecu ? |
Re: Timed Duty : Direct Port Injection
Parmas, at at higher injector duty cyles at WOT, e.g. 70%, The Fuel injectors Are open most of the time. In a port injector set-sequential injection is mainly for low load and low to mid rev emissions. if your duty cycle hits 90% they are open 90% of the time, this means also open when the intake valve is closed . It is no big deal
|
Re: Timed Duty : Direct Port Injection
Quote:
The 30% difference of a direct port injection system will result mainly in : - Wetting valves/walls with methanol - Valve Guide lubricity issues - Extra Fuel consumption - Enhance Corrosion of metals - Resulting in 100% Relative Humidty (Hurts Evaporation) Considering the next methanol build, I am planning to run and depend particularly on the direct port methanol setup while on boost. According previous datalogging injector duty cycles vary from low boost 30% to high boost 60%. What would happen if I begin direct port injection at low boost ? |
Re: Timed Duty : Direct Port Injection
If you go for a secondary methanol injection, you might consider fuel injectors. This allows for full sequential injection . Do you have a cam sensor to run sequential? Does you ECU support a second injector bank incl. transition management?
Power wise sequencial makes no difference. It is purely done for emissions reasons. If you need additional water, just use you WI system. If you want to avoid valve wetting, you need direct injection. |
Re: Timed Duty : Direct Port Injection
You can inject as early as you cannot reach MBT anymore. I start at about 0.3 bar.
|
Re: Timed Duty : Direct Port Injection
Quote:
|
Re: Timed Duty : Direct Port Injection
According to Dave Walker, owner of Emerald ECU and very exerpeicned dyno operator says no. It makes little to no difference in power. He tried it. It is mainly done for emissions reasons. As your ECU runs a cam phase sensor, it is of no extra cost or effort to do sequential. So no reason to not use it. This will stay a theoretical argument.
If you have trouble finding methanol compatible injectors, you might consider ethanol instead. It makes surprisingly little difference and ethanol compatible injectors are plently around. From a chemistry standpoint, any injector that is fully ethanol compatible should also last with methanol. Worst case buy one, soak in in Methanol in a jar and try if it still works once a month. If you go for the 350 range, you need huge injectors anyhow. For 350HP on petrol alone you already need 650cc injectors. On e85 more like a 1000cc a minute and with methanol you are heading in the 1300cc/min direction. (Numbers just scaled up, not calculated and for a 4 cylinder engine) your intake valve is open for about 70% of the revolution with the intake stroke for a 270 deg cam. So once you injector duty cycle exceeds 70% you are injecting against a closed valve anyhow. It does not really matter anyhow. If you want to maximize in cylinder charge cooling from methanol, you need in cylinder direct injection with those nice 150 bar injectors. No more valve wetting. Thing is you still need to carefully position them to minimize the spray hitting the surfaces in the cylinder. Any spray hitting the walls just cools the metal and not the air. In one of the papers I linked in the literature section of this forum quantifies the effect of this internal cooling by comparing at which IAT a engine starts to knock running either direct injection of port injection. They employed gasoline and ethanol. If the car is a daily driver, I'd seriously consider a dual fuel system. Run it on petrol and phae over to alcohol or e85 on boost (plus option water, if requiered). Ronin aka Frank Profera did such a dual fuel system with his 680HP Lotus Exige (the Ronin RS 211) running a turbocharged 1.8l 2ZZ-GE, it's "original" engine. He uses isopropanol in a secondary injection system. Ethanol would work as well, but isopropanol is easier to come by in the US in any drug store. Pothole along on 95 octane and inject the 110 stuff on demand. A little 10l fuel cell should do. |
Re: Timed Duty : Direct Port Injection
1 Attachment(s)
Quote:
|
Re: Timed Duty : Direct Port Injection
Wiithout a data sheet hard to say if they are good as a injector valve. With a dual injection system you can skip the water and use normal fuel injectors. Add charge or air to air cooling. It will gain serious power.
|
Re: Timed Duty : Direct Port Injection
I dont have a datasheet but surely better than an always ON system.
I am not interested in charge / inter coolers for now... |
| All times are GMT +1. The time now is 07:13 PM. |
Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.