Do you jet for MPH or ET?

[SUPERSTOCKRACER]

I've always heard that you jet your car for MPH but I'm starting to think it might be better to jet for ET instead.
I have also found out by raising timing you lose MPH but you gain ET.
Anyone?

 

[bobtile]

Can you repeat the question? I didn't hear you.

 

[SUPERSTOCKRACER]

Can you repeat the question? I didn't hear you.

 

[lewtot184]

mph

 

[bobtile]

If you jet for MPH, is it possible that you're going to lose ET?

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mph

That's to the point!

 

[Cranky]

Tune for consistency....

 

[bobtile]

I know how to tune my wife out.

 

[Tempest 455]

2nd for MPH.

 

[bobtile]

2nd for MPH.

Not being sarcastic, but why? I need to know.

 

[actionange1]

Tune for consistency....

I agree with this...

 

[Endangered Species]

I've never seen much in MPH and ET with jet changes on a 4 stroke engine. But I don't have EGT's or O2's either. Now 2 strokes are a different story they are a lot more touchy.

As for timing - you are correct. You advance the timing you will lose MPH but gain ET. That is because you are gaining more torque because it's starting the fire sooner.. It is firing while the piston is further down the bore and the piston has to fight the explosion (which is trying to push the piston back down) to hit TDC.
When you retard it you will lose bottom end but she'll sing on the big end. The piston is firing closer to TDC so there is not as much resistance...

 

[383man]

I agree to a point about the timing. Bill Jenkins many years back would bring in a second set of points in high gear to retard the timing some when he pulled 4th gear just for that reason. His second point set would overlap the other set for more dwell and later timing but he kept it advanced more in the first 3 gears.
I have always been told to jet for mph but if you gain mph your going to gain et to a point if your doing it with jet. Ron

 

[benno440]

whats going on between bobtile and ssr?

 

[SUPERSTOCKRACER]

whats going on between bobtile and ssr?

He's mad that my mph is better.

 

[bobtile]

whats going on between bobtile and ssr?

He is jealous of my driving skills.

 

[SUPERSTOCKRACER]

He is jealous of my driving skills.

Yes peddling it back home and tickling the gas pedal ,keeping it from stalling.:icon_compress:

 

[bobtile]

z_hemi_spare:

Yes peddling it back home and tickling the gas pedal ,keeping it from stalling.:icon_compress:

 

[SUPERSTOCKRACER]

z_hemi_spare:

Is Ziggy in the back?:icon_eyes: figuring things out on a notepad

 

[lewtot184]

if your looking for horsepower jet for mph. looking for e.t./consistency? I always thought that was a chassis/driver thing, but what do I know,...lol. do whatever you feel the most comfortable with.

 

[Longroof]

Tune for consistency....

I agree. Jet the car to change with the weather. Density Altitude goes up car slows down, Density Altitude goes down car goes quicker/mph picks up.

The old saying Lean is Mean is true... runs hard but hard on parts...

Yes retarding the timing in high gear will pick up et and mph. We did this in the class cars Stockers and Super Stockers. Hook up a micro switch to the shifter to activate msd retard when you pull it into high gear.