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Ok so the mechanic who previously owned my car - he did quite a bit of work on it! He has the rev limiter set to 7000 - he also says there's more power to be had but he didn't want to sacrifice dependability. Just got the car at the very end of Nov and was able to drive it for about a week before storing for winter here in MI. The car is an absolute beast. After reading so many posts about cams etc... I had never read of someone with the rev limiter set at 7K. Because its set high, it takes a bit of the heavy lope out of the cam - still sounds like a 1000 hp race boat!! Was curious to hear your guys feedback.
 

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7000 rev limit is not without some risk.

Even if one is willing to accept the risk the engine may not be able to make full use of the higher RPMs.

A rather too often problem with some engines and I don't know for sure about the 6.4l engine is at higher RPMs the oil supply becomes suspect.

That is so much oil is being pumped through the engine and with no active oil scavenging a considerable amount of oil remains in the engine.

While the oil pump intake doesn't suck air instead of oil what does happen is the oil the pump gets has air in it, is foamy still. This puts the main bearings/rod bearings at risk because they do not like oil with air in it. But even if the mains/rods survive what happens is power falls off. If falls off because the air in the oil causes the hydraulic lifters to become "soft" and this affects breathing at higher RPMs.

On the dyno one can see this -- if it occurs -- because the HP curve flattens or falls at higher RPMs concurrent with oil pressure falling. Watching the Engine Master videos once in a while the camera will focus on the oil pressure readout during a dyno pull and one can see the oil pressure drop a few PSI near the peak RPMs/power curve.

The 6.4l engine with its 7 quart oil pan may be resistant to this so 7K RPMs might not see sub-par oil supply to the bearings/lifters. Even so keeping the oil level topped up and the oil fresh -- oil with miles is more prone to foaming -- to give the engine an extra margin of safety is probably a good idea.
 

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Discussion Starter #3
7000 rev limit is not without some risk.

Even if one is willing to accept the risk the engine may not be able to make full use of the higher RPMs.

A rather too often problem with some engines and I don't know for sure about the 6.4l engine is at higher RPMs the oil supply becomes suspect.

That is so much oil is being pumped through the engine and with no active oil scavenging a considerable amount of oil remains in the engine.

While the oil pump intake doesn't suck air instead of oil what does happen is the oil the pump gets has air in it, is foamy still. This puts the main bearings/rod bearings at risk because they do not like oil with air in it. But even if the mains/rods survive what happens is power falls off. If falls off because the air in the oil causes the hydraulic lifters to become "soft" and this affects breathing at higher RPMs.

On the dyno one can see this -- if it occurs -- because the HP curve flattens or falls at higher RPMs concurrent with oil pressure falling. Watching the Engine Master videos once in a while the camera will focus on the oil pressure readout during a dyno pull and one can see the oil pressure drop a few PSI near the peak RPMs/power curve.

The 6.4l engine with its 7 quart oil pan may be resistant to this so 7K RPMs might not see sub-par oil supply to the bearings/lifters. Even so keeping the oil level topped up and the oil fresh -- oil with miles is more prone to foaming -- to give the engine an extra margin of safety is probably a good idea.
The mechanic had it tuned at High Horse Performance. I understand they are a very reputable shop. He says the car has never had any issues - he's taken it on long road trips etc... Now I will not be drag racing this car - this is my summer car and will be used on the road at times with clients, or heading down to the Kentucky Derby etc... He seems to be very knowledgeable as he was the mechanic at Palmen Motors up in WI - he worked exclusively on their high end performance cars for them - Scats, Hellcats etc... He did all the work himself - so hoping all is right. Time will tell.
 

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The mechanic had it tuned at High Horse Performance. I understand they are a very reputable shop. He says the car has never had any issues - he's taken it on long road trips etc... Now I will not be drag racing this car - this is my summer car and will be used on the road at times with clients, or heading down to the Kentucky Derby etc... He seems to be very knowledgeable as he was the mechanic at Palmen Motors up in WI - he worked exclusively on their high end performance cars for them - Scats, Hellcats etc... He did all the work himself - so hoping all is right. Time will tell.
Reads like you will not use the higher RPMs so the risk of foaming oil is substantially reduced and in fact probably not a concern.

In this case then you might consider lowering the rev limit back to its factory threshold, then. If you don't the risk is you use the car in a sedate manner for months and months then on a whim decide to take the engine up to the elevated rev limit. The oil is contaminated and trouble ensues...

To reduce considerably (possibly even eliminate it) the risk of foaming oil at elevated RPMs a deeper (or larger) oil pump with of course suitable baffling is fitted. If this is not present then the mechanic believes the factory setup is going to be able to deliver sufficient non-aerated oil to the engine even at RPMs above what the factory rev limit. Did you ask him if he dyno'd the engine and checked for a fall off in oil pressure at the elevated RPM limit?
 

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Discussion Starter #5
Reads like you will not use the higher RPMs so the risk of foaming oil is substantially reduced and in fact probably not a concern.

In this case then you might consider lowering the rev limit back to its factory threshold, then. If you don't the risk is you use the car in a sedate manner for months and months then on a whim decide to take the engine up to the elevated rev limit. The oil is contaminated and trouble ensues...

To reduce considerably (possibly even eliminate it) the risk of foaming oil at elevated RPMs a deeper (or larger) oil pump with of course suitable baffling is fitted. If this is not present then the mechanic believes the factory setup is going to be able to deliver sufficient non-aerated oil to the engine even at RPMs above what the factory rev limit. Did you ask him if he dyno'd the engine and checked for a fall off in oil pressure at the elevated RPM limit?
Great point you bring up Rockster - thank you. I will look into it for sure. Much appreciated. It will be dyno'd this spring - then I can answer that question.
 

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I'm building a 426 stroker for my '15 SRT and will be at a 7K redline. Has your engine been built larger?
He was on his way to building a 426 or 440 stroker. That was his plan.
 
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High HorsePerformance (they are very reputable) has taken everything into consideration for that engine, 7k is not unheard of for these engines that have been built with forged internals and proper tuning. I have a forged motor and I turn 7k and have not had any issues with it. Just do oil changes between 3500/5000 miles, regularly dump your catch can and you will not have any issues. Oh and dont drive it like a grandma, the engine is built, its meant to rev, do it. Grandma driving with a built motor is a kiss of death to them. If you have concerns call High HorsePerformance, tell them about the car and they will be more than happy to educate you on it, they are really good folks!

And the concern about foaming oil, I have never seen a case in my car of having foaming oil. These cars have proper windage trays and very good and reliable oil pumps, your not going to have an issue with that.

Congrats on the car!
-Kenny
 

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side topic, does anyone know if it's safe to take a 5.7L to 6,400RPM without upgrading the valvetrain? Mine's supercharged so I am constantly bouncing off the 5,800 limit.
 

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side topic, does anyone know if it's safe to take a 5.7L to 6,400RPM without upgrading the valvetrain? Mine's supercharged so I am constantly bouncing off the 5,800 limit.
I upgraded the push rods to the comp cam ones as the factory rods are junk. I have no worries going up to 6000....maybe 6200 on occasion but for 6400 I would at least upgrade the springs.

Although I wonder if 5800 was the limit simply because the stock motor had little to gain past that RPM?
 

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I upgraded the push rods to the comp cam ones as the factory rods are junk. I have no worries going up to 6000....maybe 6200 on occasion but for 6400 I would at least upgrade the springs.

Although I wonder if 5800 was the limit simply because the stock motor had little to gain past that RPM?
Peak power on stock 5.7 is 5,150rpm. Nothing gained beyond that - power plateau, then drops off.
-the cam profile is tuned for drivability and low-mid torque. Put more cam in these engines and they have more upper end.

By comparison, the 392 peaks @ 6,100 rpm
 

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Peak power on stock 5.7 is 5,150rpm. Nothing gained beyond that - power plateau, then drops off.
-the cam profile is tuned for drivability and low-mid torque. Put more cam in these engines and they have more upper end.

By comparison, the 392 peaks @ 6,100 rpm
Ah thanks for the correction...I was going off of this 5.7 baseline from API.
http://www.challengertalk.com/forums/2977810-post1.html

 

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probably a dumb question but, can you get the valve covers off with the Magnuson on?
 

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I shift at 6900rpms no problem with a comp 274 cam, 5.7 345. Supposedly makes power to 7400, but 6900 is the highest I'm comfortable with.
 

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I assume you are not running the stock springs correct?
Correct, I did the HHP cam package, PCM & TCM tuned by Jay Greene. Wish I would have gone with one of Jay Greene's cams so I could make the same power without revving over 6200rpm... I always wonder how much power I've left on the table not being able to shift at 7400rpm with the Comp 274 cam.
 

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Correct, I did the HHP cam package, PCM & TCM tuned by Jay Greene. Wish I would have gone with one of Jay Greene's cams so I could make the same power without revving over 6200rpm... I always wonder how much power I've left on the table not being able to shift at 7400rpm with the Comp 274 cam.
7400rpm or did you mean 6400rpm?
 

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The real issue is oil pump hamonics
I thought I read somewhere that there is also risk of oil starvation. Rgh, can't find the article/thread but I vaguely remember it was mentioned that the oil would aerate and cause the lifters to reduce lift at high RPM and that it was visible on the dyno...or something like that.
 
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