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Discussion Starter #1
Hi guys. I’ve recently been in contact with a very well known and popular mopar shop. I requested a price quote on an 2.85 upper and conservative tune on 91 for my 2018 charger. There response was that it would be extremely unsafe and I was taking a major risk of cracking a piston. Also that even a mild tune and pulley would require injectors/boost a pump/catless mids etc.

I feel like I’ve read about plenty of members running simply a 2.85/conservative tune setup with stock injectors without any issue at all.
I’m in Las Vegas so I’m sure altitude has something to do with it as well as 91.
Their suggestion was an 11k 900whp major e85 Build which is way beyond what I was looking for.

Trying to figure out whether I’m just being sold on a more expensive build or if there concerns are correct. “We have seen so many blow up on 91 with a pulley” was the message I got back. Any thoughts?

Thanks for your help and info!
 

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Discussion Starter #3
Get more opinions from other shops that specialize in this platform.

R.K.
This is one of the most reliable shops in the country. They almost exclusively work this platform and offer tunning from Tim Barth. That’s precisely why I’m torn and confused
 

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DRIVESRT.COM
Challenger SRT Hellcat
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2.85 Litens Upper, good tune and Demon Injectors. Considering this is about a 810-830HP build, it doesn’t make sense to recommend a higher E85 based 900 RWHP build if they say the pistons are already at risk of cracking with a lower HP build. 🤔

I smell up-sale.
 

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Discussion Starter #5
Being in Las Vegas, my options are semi limited. This is the out of state shop I have been consistently recommended. Being upsold doesn’t bother me. I dont mind that aspect. Telling me that what I want is completely unsafe and should be avoided is another thing. Just trying to make sense of it all. I’ve been waiting for my upgrades for almost a year. Now that I’m ready to move forward it sucks to hear that it’s next to impossible if I want to have a safe build
 

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DRIVESRT.COM
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The stock injectors and supercharger RPM would be of concern. But a simple swap to Demon injectors would be safe. Also, an upgrade on the supercharger bearings to handle up to 18,000rpm would help with durability (Jon Bond Performance).

Perhaps they are concerned with the 91 octane aspect of the equation
 

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I'm running the 2.85", although a 93 is my pump gas and I'm using ID1050X injectors based on my tuners recommendation.
 

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This is one of the most reliable shops in the country. They almost exclusively work this platform and offer tunning from Tim Barth.
That’s precisely why I’m torn and confused
Have you spoken with Tim directly ? if not you should..
 

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Look at Speedys Garage he has some great videos on his car. He has a 2.72 and was right at the limit of his stock injectors. He tells about the duty cycle of his injectors and why he changes them, he was running 10.04. I think that if you have just a 2.85 and a tune you will be ok. I just got a tune from Mike @ OST DYNO and he said if I upgraded to a ATI 10% over I would not need even demon injectors. We only have 91 here in Phoenix so I got both a 91 tune and a 100 octane tune. I just went from 11.00 et to 10.43 et and 127 to 133.7 on a stock engine with just a tune using 100. Hope this helps
 

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Call another shop or email Curt Dusterhoff. There are plenty of standup and trustworthy/knowledgeable people who are willing to provide you with info even if you are not purchasing anything from them.
 

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A 2.85 with Demon Injectors and a Pro tune should safely get you around +100 HP, I would also recommend pinning the crank pulley.
 

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This is one of the most reliable shops in the country. They almost exclusively work this platform and offer tunning from Tim Barth. That’s precisely why I’m torn and confused
So this shop being one of the most reliable in the country tells you something you didn't want to hear and you then seek out other input hoping to hear something from less reliable shops that counters what this shop told you?

Are you then going back to this shop and tell it you heard on the 'net its advice was wrong and then proceed to tell it how to build the engine?
 

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Discussion Starter #13
Yep! You got it. I’m here looking for advice from “less reliable shops”. Thanks for you help!
 

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Yep! You got it. I’m here looking for advice from “less reliable shops”. Thanks for you help!

I think your car should be making 11.5 to 11.9psi on your dash gauge. Your stock pulley is 3.35 dia. Dropping down to a 2.85 will raise your boost approx 2.5psi. 14psi on 91 is on the high side of safe, so you will need a good tuner. I know from trial and error that 15psi on 93 is about the most boost you can run. Any higher boost over 15psi you have to pull so much timing to stop detonation. That running 17psi on 93 makes less power then 15psi on 93 does.

Here is a good compromise you can consider. Stick with the tuner that gave you the advise based on safety for your motor. Ask his opinion on running a 3.10 pulley and a set of take out Demon or Redeye injectors. If he has a busy shop there should not be a shortage of take outs that can be bought for 200 to 250 a set. Your injectors are 550cc vs 700cc on Redeye or Demon. 3.10 and 700cc would be a safe 13psi upgrade that wont hurt your wallet. Really want to stick with you 2.85 plan? Redeye is 15psi stock and is oem approved to run on 91 fuel. So your car should be able to run the 2.85 14psi setup if tuned correctly. Grab a set of 700cc injectors way.
 

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Hi guys. I’ve recently been in contact with a very well known and popular mopar shop. I requested a price quote on an 2.85 upper and conservative tune on 91 for my 2018 charger. There response was that it would be extremely unsafe and I was taking a major risk of cracking a piston. Also that even a mild tune and pulley would require injectors/boost a pump/catless mids etc.

I feel like I’ve read about plenty of members running simply a 2.85/conservative tune setup with stock injectors without any issue at all.
I’m in Las Vegas so I’m sure altitude has something to do with it as well as 91.
Their suggestion was an 11k 900whp major e85 Build which is way beyond what I was looking for.

Trying to figure out whether I’m just being sold on a more expensive build or if there concerns are correct. “We have seen so many blow up on 91 with a pulley” was the message I got back. Any thoughts?

Thanks for your help and info!
I wouldn't even consider a 2.85 pulley on 91 octane with stock injectors. To me that's ridiculous. Why would you even consider taking that chance. Pin the lower and put bigger injectors in with you 2.85.
 

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I wouldn't even consider a 2.85 pulley on 91 octane with stock injectors. To me that's ridiculous. Why would you even consider taking that chance. Pin the lower and put bigger injectors in with you 2.85.
You are throwing advice without any engine knowledge on this subject. Here is the basic fuel to boost class. Higher boost creates higher cyl pressure. Higher cylinder pressure requires higher octane and\or less spark advance. Sometimes it requires both to not have piston damaging detonation or pre-ignition. Pre-ignition is the cause of detonation. Detonation will destroy a piston.

Now explain how pinning the crank would solve the higher octane requirement from the higher boost. Same on your bigger injector advice. To high of cylinder pressure that would pre-ignite on 91 octane would come into play at high load and lower rpm. A stock fuel injector would not be near it's flow limit at the 4,000 rpm range that to low of octane for cylinder pressure does damage.

"Pin the lower and put bigger injectors in with you 2.85." is your advice. If you want to run a 2.85. Put some higher octane fuel on it. Weather it is 93 or 91 with octane booster. Is my advice.
 

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You are throwing advice without any engine knowledge on this subject. Here is the basic fuel to boost class. Higher boost creates higher cyl pressure. Higher cylinder pressure requires higher octane and\or less spark advance. Sometimes it requires both to not have piston damaging detonation or pre-ignition. Pre-ignition is the cause of detonation. Detonation will destroy a piston.

Now explain how pinning the crank would solve the higher octane requirement from the higher boost. Same on your bigger injector advice. To high of cylinder pressure that would pre-ignite on 91 octane would come into play at high load and lower rpm. A stock fuel injector would not be near it's flow limit at the 4,000 rpm range that to low of octane for cylinder pressure does damage.

"Pin the lower and put bigger injectors in with you 2.85." is your advice. If you want to run a 2.85. Put some higher octane fuel on it. Weather it is 93 or 91 with octane booster. Is my advice.
Davemvegas, must be a rocket scientist? Pinning the crank is mentioned as a safety point. May as well do it while there working on it! Can't believe you even thought of it that way.
Oh ya, maybe you only take yours to 4000 rpm but not many others
 

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Discussion Starter #18
Thanks for all the positive and helpful advice gents. I’m going to continue to research and speak to people about what my options are. Much appreciated
 

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Davemvegas, must be a rocket scientist? Pinning the crank is mentioned as a safety point. May as well do it while there working on it! Can't believe you even thought of it that way.
Oh ya, maybe you only take yours to 4000 rpm but not many others

I do feel like a rocket scientist in our conversation. I thought i dumbed it down enough. The damage to pistons due to to high cylinder pressure for the octane grade of fuel. High cylinder pressure occurs around peak torque. On a Hellcat the 4000 rpm range along with the heavy car is plan with failure for a grade. I did glance at your profile hoping you were a Florida member. Nothing posted to your profile. I would like to try my luck with my 4000 rpm slug against your bottle baby.
 

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Thanks for all the positive and helpful advice gents. I’m going to continue to research and speak to people about what my options are. Much appreciated
With 91 octane I wouldn't go any bigger than 3.10 pulley and upgrade the injectors. If you go with a Lietens decoupling pulley I wouldn't worry so much about pinning the crank. If you go with a non-decoupling pulley, like Metco etc, it would be prudent to pin the crank. I melted a piston with 93 octane a 3.1 upper and a 10% lower on Demon injectors. FWIW
 
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