A buddy of mine running a 2.9 whipple making 690 ish rwhp on e85 on the stock 08 longblock just blew a hole in the side of his block. Im not blaming the tuner as we do not know why it blew.... but it left the tuners shop with a 6800 rpm rev limiter. I was always under the impression that the stock rev limit or MAYBE a few hundred rpm more was the max you want to spin a stock rod 5.4. In your opinion is 6800 rpm to much for the stock parts to handle assuming the tune and fuel are good????
6800 rpm & stock rods??
- Thread starter devilish64
- Start date
Your answer was revealed when that rod exited the block.
Let me guess...hole above oil cooler in aft section of block on driverside.
Let me guess...hole above oil cooler in aft section of block on driverside.
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I am at the same power level on 93 octane. My previous Lund tune was limited at 6325 rpm. Some datalogging at the strip revealed a 400 rpm flare, while I was shifting at 6300 the engine spun up to 6700 rpm. I quit doing that on stock internals. My recommendation is to shift at 6000 rpm.
I am interested to hear more about your buddies engine failure once he knows the cause.
I am interested to hear more about your buddies engine failure once he knows the cause.
LOL i guess your right.... it was tuned at a pretty reputable shop so I assumed they should know what they are doing. I guess the only thing that could of happend here is parts failure and the 6800rpm rev limit is very likely to blame for that.
I was close lol.
A rod exiting the block is a rpm / material of rod failure, def not a tune. A tune will melt pistons and burn up valves.
Stock block and turning up the rev limiter makes no sense except for a track only car and the guy is fully aware of the risk. Yikes!
stock internals and 6800 rev limiter spells disaster...why would someone do that ????
Not saying which is right or wrong but you'll hear two answers depending on who you talk to. Set the rev limiter high like the op to avoid bouncing off the rev limiter causing damage. Or keep the rev limiter set low to avoid spikes in rpm and putting a window in the block like the op did. I'm set at rev limit of 6250 and shift at 6000 in hopes of avoiding either scenario.
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If he did not want to risk it going boom then he should have left it stock and stayed off the go pedal. My limiter is higher then 6800 and has seen ~6800 shifts making 650+ for almost two years now. However the next time may be the last time and that's apart of it.
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My rev limiter was 7000 and shift point was 67-6800, I ran like that from the time I had a JLT, pulley and tune @ 547 RWHP up to the TVS running at 665 RWHP. It was wasn't until recently that I bumped the boost, got a Lund tune and put down 740 that I reduced my shift point down to 6500.
With 3.31 gears it was two shifts and fly through the traps at 130-132 MPH buried in 3rd gear. Shifting lower and changing into 4th slowed the car's times considerably.
There is about 70 passes on the car with that high shift point and lots of street action.
These engine work well up top, but some times things will fail, all part of the game, albeit a very expensive one.
With 3.31 gears it was two shifts and fly through the traps at 130-132 MPH buried in 3rd gear. Shifting lower and changing into 4th slowed the car's times considerably.
There is about 70 passes on the car with that high shift point and lots of street action.
These engine work well up top, but some times things will fail, all part of the game, albeit a very expensive one.
Stock 13/14 has an " over-rev feature ", allows it to go to 7K.....................for 8 seconds.
Any reason to think a 5.4 can't do 7K...................for 8 seconds ?
.
Any reason to think a 5.4 can't do 7K...................for 8 seconds ?
.
Ive seen 3 13/14's exit rods from their blocks in the same fashion at the same rpm. You can make the car go just as fast with less rpm with modding the tune....those rods are junk ford put in the 07-14 motors...yes they are all the same rods.
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I've argued about the inadequacy of the stock powdered rods since day one. There is simply no room to grow and anyone that tries to operate beyond the stock rpm limits with them is living on borrowed time. The crank and rods should be without question, bullet proof, on a 600+ hp engine.
Most tuners will set the rev limit to whatever the customer wants with in reason. I got the stock and didn't like it so I asked for 6700 so I could shift at 6400-6500. I figured bouncing the rev limit all the time was worse then the 6500 for me. No issues and if she pops it's no fault anyway.
6800 rev limiter doesnt actually mean he went to 6800
But lets say he did.
08 cj's run stock rods and go to 7k , 13,14 gt500 have a 7k rpm limiter too.
So the rods can live there, not saying its a good thing to be there all the time at that rpm.
I would look more at e85 the OP is running and look into what the oil looked like, probably a better bet is he hurt arod bearing not keeping up with oil changes when runing e85 and that caused a rod failure.
I would bet that more than just a rev limiter set to 6800rpm.
But lets say he did.
08 cj's run stock rods and go to 7k , 13,14 gt500 have a 7k rpm limiter too.
So the rods can live there, not saying its a good thing to be there all the time at that rpm.
I would look more at e85 the OP is running and look into what the oil looked like, probably a better bet is he hurt arod bearing not keeping up with oil changes when runing e85 and that caused a rod failure.
I would bet that more than just a rev limiter set to 6800rpm.
Can a compromised rod bearing really lead to a rod making a porthole in the block though?? if the limiter was set at 6800rpm i would assume that he was usung all of that 6800 rpm limit unless his tuner told him otherwise. One of the first fellow shelby owners i met told me he used to rev his to 6800+rpm because it would allow him to keep up with z06 corvettes SMH:nonono::dw::nonono: .
Without a doubt a rod bearing can cause a rod failure.
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