question on boost vs stock ign rx1

[yamahacat69]

ran my sled to a race last week was running good at 24 pounds of boost then i turned it up to 26-27 pounds sled seemed like it got slower my question wats the max boost level for the stock electrical on the rx1 before i need the msd i may be at that point but just woundering thanks guy

 

[DEC]

Whats the plug gap? Bring down to .018 . Check air/fuel,and pressure

 

[yamahacat69]

plug gap is at 18 fuel presure is at 4.5-5 at idle air fuel is at 12.5 wot

 

[yamahacat69]

anyone with any more info thanks

 

[tjc]

what fuel are you running? what turbo?

 

[yamahacat69]

vp 116 garrett 2871

 

[HURRICANE]

There is a point in every turbo system where you reach the end of the efficiency.We find this is offten caused by exhaust back pressure.I suspect that you are there at 27lbs with your 2871

 

[yamahacat69]

thanks dave that very will could be the case like i said at 25 she was running real strong at the race on the rock back in nfld but wen i figgured id squeeze little more from her its like i turned boost back to 20

 

[tjc]

Im not an expert, but at that level I have seen people running a 3071 or bigger.

 

[yamahacat69]

you mean at 27 with a 3071 good lord i must be expectin to much out of mine then

 

[sledracer]

you can see a compressor map for that turbo here: http://www.theboombopshop.com/ProductDe ... R-780371-2

It shows the efficiency starts to fall off just before 30lbs. There are of course a ton of variables that can effect the efficiency in the real world which the map wont reflect. Interesting either way.

Tyler

 

[yamahacat69]

thanks guys im goin have to read up on this exhaust preasure i guess that very will can be my issue ya learn something new every day lol

 

[rxrider]

In my view ignition will be an issue as well. At higher cylinder pressure the spark may not be strong enough to efficiently ignite the charge.
I had similar problems at 22 lbs that setting the plug gap to 0.18 fixed. But 27 lbs may be to high on the Stock ignition.