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2018 Hellcat Charger
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9 Posts
Discussion Starter · #1 ·
I have a 2018 hellcat Charger with the following mods:
2.7L Demon blower
Ported snout/bearing plate
Dual pumps with ID1300’s on E85
Williams 108mm TB
2.85 upper/10% lower
RIPA tensioner
LMI
Off-road mids
Ported heads with PAC springs
Manley pushrods
Custom Cam
Forged rotating assembly
Killer Chiller with bumper expansion tank
Sun coast converter
GHF trans
Wiles DS
Brisk Plugs
JLT catch can
Tuned by a reputable HEMI tuner who has tuned many big HP Hellcats

I ran the blower, pulley, exhaust, and fuel set up for about 4-5 months making 21-22psi and 980whp. Did great as a daily until I lost 5th and a slipping converter so I did the motor and trans build along with the KC and TB.

Put it back on the dyno tonight and picking up a ton of knock on the sensors and losing almost all boost at 18psi (goes from 18 to about 2 instantly and rich). No belt slip, it is acting like the bypass valve is opening but we cannot figure how or why.

I built this car to compete in the Texas Mile hoping to hit 200mph and I leave in 5 days. Any help or advice would be greatly appreciated.
 

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3,499 Posts
It sounds like whatever the computer is using for your timing baseline mark has been shifted, so it THINKS it is at a normal spot, but it is massively advanced. Try putting a timing light on one of the wires and comparing it to a stock hellcat versus TDC. It also sounds like the computer is in save-the-engine mode and slamming the bypass fully open to avoid the engine going all Chernobyl on you. in order to see if the bypass is open, you would have to get a camera into the housing, which you can do by drilling a hole and putting a small borescope camera with a built-in light through the hole.

Fastest way forward is to put another PCM on it and test it, then if that fails to change anything, yank off the whole blower assembly and replace it with another.
 

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Challenger SRT Hellcat
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138 Posts
It sounds like whatever the computer is using for your timing baseline mark has been shifted, so it THINKS it is at a normal spot, but it is massively advanced. Try putting a timing light on one of the wires and comparing it to a stock hellcat versus TDC. It also sounds like the computer is in save-the-engine mode and slamming the bypass fully open to avoid the engine going all Chernobyl on you. in order to see if the bypass is open, you would have to get a camera into the housing, which you can do by drilling a hole and putting a small borescope camera with a built-in light through the hole.

Fastest way forward is to put another PCM on it and test it, then if that fails to change anything, yank off the whole blower assembly and replace it with another.

Or you could not drill holes and log the bypass pids and watch what the bypass does. While you have your HP Tuner connected you you can log timing pids and airflow\fuel pids. Correct the airflow table or tq limiter that you are hitting. At this point you will probably decide not to replace your blower.
 

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2018 Hellcat Charger
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9 Posts
Discussion Starter · #4 ·
We ended up finding the problem in the tuning. As soon as it saw 110 VE it would open the bypass. For this reason we played with the injector pulse width to keep VE under 110. Car makes great power (1000+whp) and still functions and drives like a daily.
 

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2019 Challenger Hellcat Widebody (destroyer grey)
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134 Posts
May be a dumb question, but what size MAP sensor is being used, if MAP is what is used on the Hellcat? This will most likely cause a boost cut I'm sure.
 

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We ended up finding the problem in the tuning. As soon as it saw 110 VE it would open the bypass. For this reason we played with the injector pulse width to keep VE under 110. Car makes great power (1000+whp) and still functions and drives like a daily.
What is VE?
 

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Premium Member
2018 Challenger SRT Hellcat Widebody
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365 Posts
^^Volumetric effeciency
 

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Challenger SRT Hellcat
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138 Posts
Of the engine or of the injectors?
Google is your go to on this subject. But i think the highlight is a 4 stroke natural aspirated engine. It should pump 90% of engine size thru the throttle body and out the exhaust every 2 revolutions at wot. I have seen VE calculators for air to fuel ratio efficiency, so i guess VE can apply to anything that flows a volume of air.
 
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