Getting off the line. Help!

[Unholy707]

There is a limit and that limit depends on the supercharger efficiency range. Once you get outside that range more RPM from the supercharger rotors won't mean any more air or any more power. I don't know of anyone still using a 2.5 pulley and those that tested found anything below a 2.70 actually lost power and or went slower at the track. You'll be able to get a log from both of yours and that'll be a good comparison.

Are you talking about a 2.70 and a 10% lower?

 

[Demid22]

There is a limit and that limit depends on the supercharger efficiency range. Once you get outside that range more RPM from the supercharger rotors won't mean any more air or any more power. I don't know of anyone still using a 2.5 pulley and those that tested found anything below a 2.70 actually lost power and or went slower at the track. You'll be able to get a log from both of yours and that'll be a good comparison.

Roger that speedy. Thank you so much for you input. Sorry its been such a hassle. Im about to finish up and see what we got. Thanks again bud

 

[Demid22]

There is a limit and that limit depends on the supercharger efficiency range. Once you get outside that range more RPM from the supercharger rotors won't mean any more air or any more power. I don't know of anyone still using a 2.5 pulley and those that tested found anything below a 2.70 actually lost power and or went slower at the track. You'll be able to get a log from both of yours and that'll be a good comparison.

What kind of aircharge should i be looking at? My absolute max im seeing is 1800.

 

[Speedy!]

Are you talking about a 2.70 and a 10% lower?

I don't think there was a 10% lower but it's been a while. Hellno from this forum did some back to back track testing, you might find his posts.

What kind of aircharge should i be looking at? My absolute max im seeing is 1800.

A few variables but my 2.72 hovered around 1600 to 1650.

 

[Demid22]

A little update. Got the blower back on. Ran a log. Pulled 18lbs over the previous 16. However supercharger had an air bubble in coolant so air charge temp was high. Got that fixed. Did another pull back to 16lbs on boost. Air charge was 1700 or so. However for this second log i did 2 pulls. Both pulls had a hiccup of sorts and shut the throttle and boost off. Waiting on jon to review the log. the log shows tps dropping to 50 % during the pull but my foot was planted down so... A limiter perhaps?

Additionally i didnt get a chance to swap pulleya and log it was getting late. Im going to try when i get off tonight. But working 12hrs in ICU we will see how i feel.

 

[Demid22]

alright next update. got off. swapped to a 2.78 pulley. made couple pulls and logged them. heres what i know. Boost gauge is now only showing a max of 14 (logged 14.5). air charge and air flow is additionally down.
i was making 15lbs on a 2.85 93 pump gas setup so....im boggled by the 2.78 e85 only making 14.5.
another note. i logged the 2.55 pulley yesterday before calling it a day. again 2 pulls. each of these pulls had a hiccup mid pull. it bucked pretty violently during this "hiccup". after reviewing the log, it appears on both pulls, mid pull i have the throttle WOT. but the it dips, the injector duty cycle drops, the boost drops, the TPS drops, even though i never let off the throttle.

another thought....when reviewing the logs side by side.... the bigger upper pulley, 2.78, the MAP graph appears nice and smooth throughout the pulls, however, next to the 2.55 pulls , the MAP is very spikey jumping all over the place. Im unsure if this is normal or not. i wouldnt imagine so, but hey im still learning. i have forwarded all of this to Jon. He has had a busy few days working on the shop and baby stuffs. so until he can review it thoroughly i figured id post here to see what you all thought. attached is the two logs.

 

[Speedy!]

Ok, so with a reference point I think things seem to be OK from a blower perspective based on the logs. Your 2.78 pulley log makes around 1600mg of air charge. The 6-1-23 log I'm assuming is the 2.5 pulley and aircharge there is over 1700mg. That seems to line up. You've removed your cats so things will flow a bit better than a car with cats and likely the difference in boost pressure you're seeing.

The throttle thing is interesting and I can see it in the log. Commanded throttle DC jumps to 100% when the issue occurs. I'm not a throttle expert on these but wonder if it's getting sucked closed and the motor is weak. Jon will have more experience there with other customers.

 

[Demid22]

Ok, so with a reference point I think things seem to be OK from a blower perspective based on the logs. Your 2.78 pulley log makes around 1600mg of air charge. The 6-1-23 log I'm assuming is the 2.5 pulley and aircharge there is over 1700mg. That seems to line up. You've removed your cats so things will flow a bit better than a car with cats and likely the difference in boost pressure you're seeing.

The throttle thing is interesting and I can see it in the log. Commanded throttle DC jumps to 100% when the issue occurs. I'm not a throttle expert on these but wonder if it's getting sucked closed and the motor is weak. Jon will have more experience there with other customers.

Whats ur take on the Map graph being smooth with the 2.78 pulley and jumpy and spikey with the 2.55? Belt slip?

 

[Speedy!]

Maybe a tick of belt slip, maybe not. I didn't see a ton of movement in MAP except where the throttle did it's thing. I think if you look at how much the MAP value is moving it's not much if I remember right.

 

[jonx96]

I haven’t had time to look today. Maybe late tonight or in the morning but if it is commanding open and is closing 99 percent chance it is the motor. The weird thing is it didn’t start until you pulled the blower. Maybe a coincidence

 

[jonx96]

The zoom feature can really change those spike lines as well. I don’t think for a 2.5 you are having terrible slip and it is not your problem if there is one

 

[jonx96]

Your fuel trims need cleaned up a little bit but I haven’t wanted to change anything like that until it’s final

 

[Demid22]

Map graph, ones nkce and smooth (2.78 pulley.) one is janky and all over the place (2.55 pulley)

If you say its not a big deal than ita not a big deal. Just trying to run this issue down. And i always thought spikey janky maps can indicate belt slip

 

[Demid22]

The zoom feature can really change those spike lines as well. I don’t think for a 2.5 you are having terrible slip and it is not your problem if there is one

Oh ok. Thinking it was belt slip i about pulled the trigger on an ati 10 last night but thought i should wait until you all reviewed

 

[jonx96]

Oh ok. Thinking it was belt slip i about pulled the trigger on an ati 10 last night but thought i should wait until you all reviewed

Your slip is not bad. But even the ati in stock size is better than a stock dampener. You’d be better off the 2.78 and 10 lower than the 2.5

 

[Demid22]

Your slip is not bad. But even the ati in stock size is better than a stock dampener. You’d be better off the 2.78 and 10 lower than the 2.5

Why is that, just curious? Is it lighter?

 

[Speedy!]

More belt wrap.

 

[Demid22]

Your slip is not bad. But even the ati in stock size is better than a stock dampener. You’d be better off the 2.78 and 10 lower than the 2.5

Roger that. It has been ordered

 

[16GoManGoHC2]

May have spun the coupling on one of the shafts. I saw a similar thing before if failed totally running a 2.72 upper and +10 lower.
I haven’t had a chance to look at your logs is the bypass valve voltage where it should be? It could be getting blown open, had that happen too.

 

[Demid22]

May have spun the coupling on one of the shafts. I saw a similar thing before if failed totally running a 2.72 upper and +10 lower.
I haven’t had a chance to look at your logs is the bypass valve voltage where it should be? It could be getting blown open, had that happen too.

From what I can tell and John with his expertise that bypass is not opening. I hope I didn't spin the coupling. I'm swapping to a larger upper pulley and a 10% lower I ordered it last night