Whipple 91 Octane/Low boost?

[Streya6G]

Hey guys, quick question... I'm in an area with an elevation of 4300 and I am running on 91 octane with the 3.75 pulley. 72 lb injectors and the 132mm TB. The boost is reading roughly 5-7lbs and I am curious if it is the air being thin and hot or what. Not sure if the boost should be higher or if this is exactly what should be expected. I'm a noob when it comes to this.. It's all pretty new to me, so any help with the issue would be appreciated. In the flare software, I have everything defaulted if that gives any info. Thanks!

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[PowerAdderGT]

You make about .74 lbs less per 1000 feet of elevation, so at 4300 feet your down around 3.2 lbs from sea level. You will need to pulley down to make up for the thin air.

 

[Roh92cp]

I would also ask what boost gauge your using. Most boost gauges are not going to read dead on accurate and some may be off by 2-3 psi.

 

[Reds197]

I live in Denver. Every blower I have had required a minimum of 2 pulleys smaller to hold the advertised boost of the kit. I would pulley down and enjoy the power!

 

[Streya6G]

The boost gauge is a glow shift. Now if I were to pulley down to the 3.625 or smaller, wouldn't I need to turn on the octane adjust on the whipple software to ensure knock doesn't happen. And with that on, it wouldn't yield the advertised boost either because of the timing retardation it seems. And with running only 91, it's recommended to have the adjust on.. But you guys are saying with the elevation, it's all good anyway? Just trying to get as much info as possible and make the right decision without hurting the motor. More input would be great, and thanks for the replys and info!

 

[Whipple SC]

Turn knock limiting off in flight control. You should be done 1-2psi down but power % would be still higher than sea level. Timing advances by itself with the lower cylinder pressure.

 

[Streya6G]

Whipple SC, so with the 3.75 pulley with 91, keep everything in the flight control software as default except turn the knock limiting off? Or were you referring to the 3.625 pulley and turn knock limiting off?

Also, would it be perfectly fine to run it with the 3.625 pulley with the knock limiting off at this elevation or should I only use the 3.75 with this elevation with the knock limiting off... Just trying to ensure everything will be good to go! Thanks for the help!

 

[Whipple SC]

Whipple SC, so with the 3.75 pulley with 91, keep everything in the flight control software as default except turn the knock limiting off? Or were you referring to the 3.625 pulley and turn knock limiting off?

Also, would it be perfectly fine to run it with the 3.625 pulley with the knock limiting off at this elevation or should I only use the 3.75 with this elevation with the knock limiting off... Just trying to ensure everything will be good to go! Thanks for the help!

Just turn it off in all circumstances. Yes a 3.625" is fine at that elevation with 91 octane. Knock limiting cuts the throttle, knock sensor and timing advance/retard still 100% active and functional.

 

[Streya6G]

Awesome, thank you for the quick help and responses! How low of a pulley size could I safely go for a daily driven setup on 91 at this elevation with the software settings you suggested?

And if I were to put race gas in the car for track days here and there, with the 3.25 pulley, would the knock limiting need to be back on by chance?

Also, if race gas were to be put into the car with the 3.625 and the 3.75, still leave the knock limiting off and it will adjust by itself no problem?

Once again, thanks a bunch for the help!!

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