Experimenting With Trumpet And Cam Timing

[smckeown 1]

As I ran out of time during the RR session, and being one for details, I had some thoughts about self experimenting, and I thought I'd get your opinions on it.

 

So i'm thinking, as I assume I can change the cam tinming myself using the catacam locking vernier, I know dave advised max 1-2 degrees swing and shorter trumpets (actually he didnt mention shorter trumpets but I somehow stumbled across an old post of his the night before my mapping session).

 

So could i choose a strip of road, cruise at say 30, stick it in 4th, and time how long it takes to get to say 100. And perform exactly the same test with all possible combinations of timing and trumpet size noting the time it takes to get to 100 each run.

 

Would this realistically give me more information as to the possible best combination ?

[Jonmurgie 2]

I would personally think that you will only be able to see the benefits of those kind of small tweaks on a dyno where everything else can be kept at a constant. On-road tuning might work for Scoobys and the like but that's when your adding 30/40bhp at a time which is noticable, with what you'll be doing it will be a case of small imcreases in places you probably won't notice without a graph.

 

However, there's nothing to say that you have to use the same dyno to see which works best... just use the same dyno between each set of cam timings and trumpet size. A before/after is possible from any dyno no matter how bad a reputatio it might have, so maybe it might be easier to find a more local dyno for you to hire for an hour or so for some back to back testing

[petert 550]

That's a good way to test. Find a straight, flat section of road. Do at least 3 timed runs, taking the average. Get someone else to do the timing however. If you've got datalogging in your ECU it's even easier, as you can see when you put your foot down and off (from throttle % change), and the exact time you did it for.

[jackherer 543]

So could i choose a strip of road, cruise at say 30, stick it in 4th, and time how long it takes to get to say 100.

 

thats KPH you're talking about there I assume Sean?

[M3Evo 0]

I'm probably wrong here, but I'll say it anyway:

 

If you make a change which causes the engine to ingest more air and increase power, shouldn't you be adding the corresponding amount of fuel to that air to avoid running lean?

 

That being the case surely the ECU, which is presumably running Alpha-N, has no way of knowing there's more air going in?