VP Fuel Application

**DuckLn** · 08-22-2011

How many of you have tried VP Motorsport 109 or other VP fuels on outboards?

From the manufacturer website about Motorsport 109:

Recommended for applications with CRs up to 15:1. In engines that can run on pump gas, MS109 is a direct replacement that produces up to 5% more horsepower than premium unleaded. In fact, MS109 makes more power than any other unleaded fuel on the market with the exception of VP’s MR-PRO4.1, which is used by most top teams in AMA Supercross and Outdoor Nationals. Compared to other unleaded fuels, MS109 offers better detonation protection as well.

I am hesitant to run much more of this as I'm afraid of damaging the motor but the tech states it actually runs cooler than pump gas on slightly modified motors such as my 30 3 cylinder yammer hammer.

**Mark75H** · 08-22-2011

Unless your compression is between 12 and 15, it would be a waste of money

(at 15:1 I have 275# cranking compression)

**OUTBOARDER** · 08-22-2011

Originally Posted by Mark75H

Unless your compression is between 12 and 15, it would be a waste of money

(at 15:1 I have 275# cranking compression)

on a four stroke will see near max on comp test.

On looper with %100 percent volumetric efficiency, " because of exhaust plugging"
won't see swept comp until it is on the pipe.
Comp test #'s are a product of intake, crankcase comp , trapped comp ratio and cranking speed during the test.
Highest ever saw on a test for 2-stroke outboard was 225lbs.
Trapped + crankcase were set at 10.5:1.

**Powerabout** · 08-22-2011

I remember a test Hot rod did on a street 350 running on the dyno
it made most HP and TQ with the race fuel and they were surprised as it was only 9.?:1 motor.
Fuel guy ( I think is was VP) said they would expect that due to the way the fuel burns in other words you are getting something for your money

**Mark75H** · 08-22-2011

Cars have auto advance software that advances the timing until it pings or hits a preset limit. Outboards don't. You might see some power increase if you use something like this and increase your ignition timing ... or maybe not.

The only way to know is to try it.

**DuckLn** · 08-23-2011

Thanks - My motor has a WOT timing setting and an idle timing setting that can be adjusted to user's desired spec. Also, the carbs im using have optional larger main jets or I can bore them out a little to accomodate the oxygenated fuel so maybe there is something to gain here.

Any other fuels or additives I should try?

**Mark75H** · 08-23-2011

Larger jets are only needed if you are too lean. Check the color of your spark plug insulators. If normal, larger jets aren't going to help. Generally factory jets are rich enough to accommodate a little variation and the way to go for that last microscopic power increase is leaner.

The majority of additives are snake oil. There are some that work but their safety is questionable.

**YAMAHAFASTCRAFT** · 08-23-2011

Why waste the money on race fuel if it is not needed. Unless you are 180 Compression not needed

**biggdave92** · 08-23-2011

Originally Posted by Mark75H

the way to go for that last microscopic power increase is leaner.

......

**Mark75H** · 08-23-2011

Pete DeLackner won the 36 Runabout championship because he was one of the few racers that knew about a special optional adjustable main jet on the 35hp Chrysler ... that let him lean off the motor for maximum power rather than running the jets that came in the motor.

It is always safer to run a little rich, so that's the way they are all shipped.