Raptor Powerjet For Drag Racing

[neil68]

I have been experimenting with the JPM Raptor power jet kit and am looking for your experiences.  2332, 51 IDAs with Raptor 44 venturies and the most responsive jetting I’ve found thus far was F2, 135 main, 120 power jet and 220 air.  I don’t have any smaller mains, but could try to find some (the only person who would share their combo on FB, had good success with 125 mains).  My air-fuel gauge is still indicating a rich condition 10.5-11.5 on the drag strip. I’ve tried various power jets, but they don’t seem to affect it much: 80, 100 and 107.5.  Also tried F4 tubes but that was even richer.

Power jets are supposed to work under guidelines of reducing the main jet 25%, and i’ve already done this:  180 to 135.

Anyway, your experiences would be appreciated!

[jim martin]

Neil I did not realize you were running this when we met at mission
For the great Canadian.
Let’s make a time to talk and I’m sure I can guide you through carb setup.
Jim

[neil68]

Hi Jim, I was not running the power jet attachment at Mission Raceway because I was having difficulty jetting it. I was hoping someone in Europe may have this Raptor kit and would share their jetting.

I experimented some more at the drag races last weekend and I think I’m getting closer with:  F2, 135 main, 120 power jet, 220 air, 60/120 idle.  However, it’s still running rich, so I may need to pick up smaller main jets.

[PPRMicke]

Hi Neil
How's your ignition? If it does not have enough ignition energy then the wrong AFR (rich)
On Andreas J engine with the same JPM fuel parts was 140  main  F7      190 air  (110 powerjet) mikuni jet)   (42mm) (258 hp  (2332cc)
On the 4 "engine, the only difference was the 180 main 44 mm  (282 hp)
ignition old MSD 6Al (analog) the best
/// Micke

[RMS Boxer Service]

When are your AFR meter showing 10,5-11, part throttle or full throttle??

If the engine runs rich at part throttle and in the middle rpm range then the
main jets are too big. Engine runs on idle curcuit up to appx 2500 rpm on IDA's
depending on engine set etc.

If the engine runs rich at full throttle in upper rpm level it can be both the main
jets and powerjets that's too large.  How big are the jets in the powerjets??

/Rolf

[neil68]

Micke:  Complete MSD ignition with 6AL digital box, distributor, blaster coil, 8.5mm leads, etc. Beetle ran a 12.7 second 1/4-mile two weeks ago (without power jets), so I believe the spark is good.

Rolf:  Running rich throughout the rpm range 10.5-12.0.  Currently using 120 power jet, however, I also have 107.5, 100 and 80 power jets to experiment with.

I live at 1,000m elevation, or 700-800m track elevation depending where I race.  MS230 heads, Wasp Stage 2, Raptor cam 274 degrees, 10.8:1 CR.  I just reduced the idle jets to 60, and will see how that works at Friday’s drag races.

I noticed that everyone seems to use F7 emulsion tubes, which I haven’t tried yet.

[jim martin]

It’s been awhile but if I remember f2 are  going to run rich
I have to find old jetting info but I remember using a f7 it got rid of
Hesitation during progression and aloud for better top end jetting

[RMS Boxer Service]

What about fuel pressure ?? Are you sure it's not too high??
IDA´s are really sensitve to fuel pressure.

/Rolf

[neil68]

Fuel pressure regulator was set at 3.0 psi, however, I will double- check!

[jim martin]

We need to back up here , Neil you say best responsive jetting , I’m going to say brakes on
And let’s back up . It’s all about combo gearing to motor if your looking for response with a 44 vent depending on gearing and
Cam heads ect there may not be enough airspeed through carbs causing week or poor signal.so drivability can be a issue.
This may be why your having issues, and adding a third jetting stage is possibly causing more issues .you need to break it down into multiple States of tune .fuel jets first. idle /cruise , mid and finally top end , adjust tip in with pump shot
And fine tune with air,
I love tunning and this is a huge topic , Neil I will recommend to step back , dial car in without the 3rd jetting stage
And get it nailed without raptor power jet then add the system in

[PPRMicke]

Fuel pressure regulator was set at 3.0 psi, however, I will double- check!

Ps  2.5 psi is better for the level  (3.0/3.5 needle valve)
you can get a fuel pressure increase during take-off and up to 330 feet (g x fuel weight) weight of fuel in liters is 0.73 grams)
/// Micke

[neil68]

Pressure is 2.8 psi and 3.0 mm needle valve.

So, in the meantime I managed to over torque one of the power jet banjo fitting and broke it! Will have to set them aside for a while.