dmzamora

Hi guys

1. Did some of you that changed the original air filter to the high performance one from HPI/MotorSaver noticed a great increase in fuel consumption? My 21BB gained a lot more low end and accelerates way better, but I noticed my runtime decreased at least 30%.

2. To solve the leaning issue wheh tank is low, I've tried a Perry check valve on pressure line. However, the engine gets hardly flooded almost immediately when the valve is connected. It dies in about 5 seconds, no time even to try to close the needle. So I took it off.

Anyway, with the new filter it seems that the leaning issue is history. Maybe the increased air on exhaust gives me a little more backpressure. The engine only start to bog when there is no more fuel on tank.

Higly recommended and cheap hopup, but it will drain your fuel really quick

Daniel

adeoliver

My Feedback: (4)

Air flow is one of the major key factors that no one thinks of, my buddy and I had bought some filter elements from duratrax for our small blocks, and couldnt get them to run for the life of us, about a week had passed trying to tune the engines, and I found out that there was almost no air flow through these elements, so I bought some Traxxas 3 stage filters and wow, what a huge difference!! Brought the engines to life and never had any problems. Always make sure you can suck air fairly easy through the filter before installing.

Avalanche

I'm of the opinion that putting a check valve in the pressure line is not a good idea at all. The exhaust pressure line is meant to provide variable pressure to meet demands of the engine. What I mean is when you are full throttle and high RPM, there is lots of pressure and therefore lots of fuel being pushed through the line, when you let off the gas the pressure drops to match the low fuel requirements of a relaxed engine. Putting the check valve in will maintain the highest pressure reached during the run, even after you let off the gas, therefore flooding the engine. If you put the check valve on and it helps your engine you are obviously making up for a lean condition and only putting a band-aid on a problem. A properly tuned engine shoouldnt see any real lean out condition until the fuel gets low enough to expose the pickup under acceleration and cornereing, usually 1/8 tank or lower, just like any other R/C.

badboy2

My Feedback: (13)

do you think my filter set up is ok ...cuz up until now i ve had problems in tuning ..

badboy2

My Feedback: (13)

do you think my filter set up is ok ...cuz up until now i ve had problems in tuning ..

dmzamora

Badboy2: your setup apparently is OK, but remember that the engine will run a lot richer with this filter. Turn it on, do a few passes to warm up the engine (usually 1.5 min), put the truck on a stand with the wheels off ground, go WOT an tune the HSN to the higher RPM possible, then turn it back 1/8 turn.

For the low end, pinch the fuel line right before the carb nipple, the engine must run for about 4 seconds and start to die. If it run more, you're too rich, less and you're too lean. And always be sure that the MSN is set at factory default.

Avalanche: now I agree with you. However, Savage has a problem with fuel tank, causing lean conditions below 1/2 tank, even when well tuned.

Daniel

Avalanche

Whoa!!! Do you really do your top end tuning with the wheels off the ground? I would certianly suggest you do it on a flat level surface using top end runs as your barometer. These high RPM engines do not like to run with no load.

As far as the Savage having a problem with the tanks, I hear that alot but mine is rock solid until it gets below 1/8th tank, and thats the case with any Nitro vehicle. My fuel system is all original and still works great. I think alot of people are tuning these things before they get to operating temp.As long as they run good when they are warm it doesnt matter what they run like cold.

DFF

Agree, I hear a lot of tuning problem due to the tank, but had none on mine.

I think that what helps a lot is to buy a BIG volume fuel filter and throw it underneath the tank.

It act as a little reservoir and always feed the engine.

That's what I have and no problemo at all !

I see as well a lot of guys putting their fuel filter in a vertical position or having the fuel line almost vertical behind the shock tower. It doesn't help the engine to get the fuel...

DFF

dmzamora

Avalanche

This was the first time I did tne HSN tuning with the wheels off ground, and of course I payed great attention to the engine RPMs.

I think its due to great mass of the wheels, but the top RPM off ground is pratically the same that I get after a 5sec WOT pass.

Just protect your ears 'cause it's REAL loud...

Daniel

dmzamora

Avalanche

This was the first time I did tne HSN tuning with the wheels off ground, and of course I payed great attention to the engine RPMs.

I think its due to great mass of the wheels, but the top RPM off ground is pratically the same that I get after a 5sec WOT pass.

Just protect your ears 'cause it's REAL loud...

Daniel

badboy2

My Feedback: (13)

i think valanche was right i read t somewhere that if you are tuning u should have your wheels on ground..any way id rather run rich than lean