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Roman last won the day on March 14

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  1. Roman

    kpr's starlet

    Damn you Markku! Damn that is a sweet result! So coming to drag day this year?
  2. Roman

    kpr's starlet

    I dont know but you're car was already bloody fast so it must be a freaken rocket now.
  3. Roman

    kpr's starlet

    180hp at the treads is my guess
  4. Sooooo After about a year and half break, made it back out to a trackday. It was stunningly awesome fun! Excuse the camera angle and shitty audio etc first time using my crappy gopro type camera (reminds me why I hate these things) Something funny, for about the last... forever I've had this issue where the front left of the car dives under braking. Have double checked all of the bushes, brakes, alignment, etc... Turns out that one of the handbrake cables has been jammed so its been pulling the right rear handbrake about 1/3rd of the way on all of the time! After fixing this, hooooly shit my braking distances have shortened up sooo much! Such an awesome difference. Only issues I had on the day were a piston jamming in one of the front calipers when trying to switch pads (time for a caliper rebuilt perhaps) and at the end of the day I broke teeth off another e-throttle gear. But then I realised a while back I turned off all of my smoothing in the ECU to stop that from happening. woops! Will turn that back on and should stop any further dramas hopefully. All said and done A+++++++ will trackday again
  5. The bellmouth I made previously for a 3" inlet pipe with same geometry is bloody huge hahaha. Cant wait to get flowbench setup and do some nerding with it.
  6. Yeah make a jig so i can trim each side accurately. Will be enclosed in an airbox eventually. Gonna make a flowbench so i can test a few different schemes.
  7. Made a 3 piece mould so i could get a full bellmouth lip going on. Turned out ok but I will buy some more carbon sleeve in the next size up so the bell can be made from the sleeve too. Will be much nicer as well as easier to make! Getting a little better though as this is the fiddliest / smallest complex shape ive made so far and turned out not too bad. I used a 0.8mm gap between mould halves but will try 0.5 next as there were still some areas with too much epoxy.
  8. Oh yeah good point about lambda 1. duh. There's a diesel specific version of the 4.9 that I think has smaller inlet holes to the sensor to prevent damage from particles etc, might be a good one to get for that application
  9. And you really need gas flowing past the tip to get a good response. If its just in still air it might be unresponsive.
  10. Not sure but just keep in mind that it can only go from about 8:1 to 22:1 so might not work at the sensitivity you need. And keep in mind it heats the sensor tip to 850 deg which sounds not fun if its potentially explosive
  11. Roman

    Tyre tread pattern vs width

    Well you're not going to get an original feeling for the car by putting modern high grip tyres on it, even if they are 165 width. Buy some triangles or linglongs or something and wallow about disastrously like it would have on factory fitted tyres haha.
  12. Roman

    DIY Fuel injection thread.

    I've heard that some people find an approximation of the injector deadtime by alternating between single then double pulse (per cyl) until the AFR matches for both results But as you say the fact you're making that change changes how well it combusts etc anyway so not really a reliable test I guess. But if it's 20% difference (at presumably low load) perhaps it could be deadtimes being a little off?
  13. Roman

    DIY Fuel injection thread.

    I agree however the further you have the injector from the head, as is being propositioned. The more relevant injector timing becomes because you have inlet harmonics trying to push fuel back out top of the runners. Which doesnt really matter when the injector is right by the valves, but a very big problem if they arent. I have found that on a cold start the engine will start waayyyy nicer when you use an injector timing that sprays when the valve is open, in order to minimize wall wetting. As it takes so bloody long to evaporate when engine is cold. A friend of mine tried the same thing with E85 which is notoriously awful for cold start and found massive improvements. The recent idling improvements that AJG193 recently found by going to 2 squirts per cycle is basically a crude way of circumventing the problems of batch injection's asymmetrical injector timing. If you have your engine idling and slowly advance through the injection timing range it makes such a difference it can either make your engine rev a lot higher or make it stall. As the combustion quality changes so much. When I tried having a fuel map using 100% staged outer injectors (even though fully sequential) it was an absolute shit show for idle and transient conditions, even after a lot of time trying to optimize it.
  14. Roman

    DIY Fuel injection thread.

    So I tinkered with having outboard injectors, about 3/4 of the way up the runner. And its an absolute shit of a thing, because of wall wetting like BobbyBreeze says. You are wetting this absolutely massive area of the intake runners with fuel, and some of that fuel takes time to evaporate and end up back in the air/fuel mix and into the engine. So for a real life example of why this sucks. Lets say you tune your car in 4th gear, at the rate of accelleration you are going. Some of the fuel that you spray in at 4000rpm doesnt get into the engine until you're doing say 4250rpm. So if you get all of your air fuel ratios correct, it only suits that one rate of accelleration because you are actually tuning "Ahead" slightly. So now when you are in 2nd gear, your air fuel ratios are now a mess because the fuel you spray in at 4000rpm, ends up in the engine at 5000rpm. (or whatever) And the transient throttle is just shit. It will work okay if you keep your entire intake manifold as hot as possible to minimise wall wetting, mine was insulated from the head so stayed quite cool. But I found it was more of a headache than it was worth so just went back to normal port injection and my throttle response was night and day difference. I was using 8 injectors total so I could blend between them as desired but found it still wasnt really worth it even just for full load high rpm. Other people have tried the same with greater success so perhaps it was my choice of injector, or the angle, or whatever. But yeah it sucked.
  15. Roman

    DIY Fuel injection thread.

    Common practice for any aftermarket ECU install is "Fuck those return pins" But yeah after looking into it, such a waste! Could tell so much if ECU was configured for it. "Hey, when engine gets hot coilpack number 3 starts to misfire 6000rpm onwards" instead of "......" And the knock sensing capabilities are just mind blowing. Strapping a mic to the side of the engine is so ghetto by comparison hahaha. At some point I want to see if I can get anything meaningful with a Teensy 3.6 by doing a burst reading just after ignition on the return pin. Then analyzing the waveform for however long that takes. (Doesnt need to read every single event) It should have enough speed to capture at least 1 degree of crank movement at 4k+ rpm. Will get there eventually...