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link g4 custom TDC

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Translator. Hi everyone I can't understand these parameter changes in a 4-cylinder in-line engine. the function of this change what it is used for. thanks

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This is designed for odd fire engines where there isn't an even number of degrees of rotation between consecutive TDCs. The Dodge Viper engine is just one such example where custom TDCs are required. It's pretty rare though and is really limited to V configuration engines with unusual bank angles. Unless you've got a pretty unique crankshaft this isn't required for an inline 4 cylinder. If you take the number of degrees in an engine cycle (720) and divide it by the number of cylinders (10 in the case of the dodge V10) you'll get the required bank angle for an equal spacing between TDCs - In the case of a V10 it's 72. The Dodge Viper engine is a 90 degree V10 which requires the custom TDC feature.

Translator. hello I understood that this engine was not needed but unfortunately I find it inserted. what causes in this case, instability, or some ignition and injection failure? . is it better that I take it off? and why did they do this, is there a reason? . is it therefore an error? the crankshaft is not special all points are 180 degrees. a mistery . thanks

Yes, the setup you have shown in your pictures would not normally be correct. I suspect somebody has done it to overcome some other issue but we can only guess. Effectively Cyl #2 and Cyl#3 will have the spark 5deg later than the other two cylinders so it is probably not going to have large effect on anything.

If there was some reason to need 5 deg less timing on certain cylinders then most tuners would do this using an individual cylinder trim rather than "faking" the TDC points. Unless they have some inside knowledge that you dont such as the crankshaft has been indexed incorrectly when grinding.

If you are now tuning this engine and you believe the crankshaft to be true 180deg spacing then you should turn off the custom TDC before progressing.

translation . this modification was not made for my single engine, but is inserted in the base map of the vipec v 88 G4 plug in for all yamaha 1800 engines. I know these engines and I can say that they have heat and detonation problems when you get more power, and they probably did it for this, but I don't mean because they didn't use the trims for both ignition and fuel, and they used this strategy. I am learning now and I thought I could trust the base maps, I thought I only had to refine things, instead also with the new versions of vipec V88 R G4 + plug in always for the same 1800cc engine I already encounter many setting problems however thanks. you will often hear me asking questions because the topic interests me very much thanks again

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