02PRUV

Hi Guys,

I have an stock LS1 engine that I installed valve springs and rod bolts in and turboed. Made 550whp on 12psi and 621whp on 14 psi with E85 on a Dyno Dynamics Dyno. I drive it round 99% of the time on the 550whp and it's been going fine like that now for 25,000km's and has 155,000km's on the engine in total.

I installed the Lingenfelter 2 Step and with -15 degrees and 4800rpm which gave me 10psi boost off the line. I used it for 1 day and the engine started knocking. Pulled the engine out of the car today and found nearly all the conrods bent.

I know the engine was being pushed to start with but it's strange that as soon as I install the 2 step it bends rods.

Now my question is as far as I thought the way the 2 step works it wouldn't put any extra stress on the rods. What I want to know is if I'm wrong and it does put more stress on the rods using a 2 step with boost and I just found the limit of the stock rods or if something is setup wrong and it did the damage from incorrect setup. I just want to make sure I didn't set something up wrong and I will do damage again when I get the engine running.

Any educated information welcome.

Also now I need some 9.0:1 comp pistons, some good rods, a turbo cam. What supplier can set me up with these parts for a good price

Old Geezer

iTrader: (3)

That 2 step kills the spark. The injs continue to add fuel. That, plus the boost, plus the compression ratio, put the rods into a SERIOUS compression overload situation....IMO, you "sledgehammered" them to death.

got-a-ls1

iTrader: (12)

failing to see how that in any way would cause the rods to bend under the 2 step. the 2 step simply lets the unburnt fuel into the exhaust manifold and where it ignites in the exhaust/turbo. cylinder pressures should be way less in the manifold where the spark is cut.

id say something else is going on. any damage to any of the pistons?? i would think a ringland would break before a connecting rod.

slow67

iTrader: (2)

Highly doubtful. The only way that would have happened is if it hydrolocked, which even cars running pure methanol can run on the 2 step without hydrolocking. The rods experience a greater compressive load if it does fire. It is harder on the rod bolts, but not likely for anything to happen there either, unless your hitting the 2 step at 7,000+RPM.

SPRAYED 01

iTrader: (22)

Very interesting,i always hated using the 2 step. It does feel very violent on the engine.

bad6as

iTrader: (17)

In for more thoughts on this. I've ran the lpe 2 step on my car for over 2 years now.

Texas_WS6

iTrader: (9)

How much torque are you making at 4800rpm and 10 psi of boost? It could have ben due to hydrolocing but I dought it. Might have just been the torque load on the rod with that much boost at the lower rpm once the two step was turned off. I would not blame the two step. Did the boost spike up imediatly right after the two step turned off and you loaded the engine? If so how much?

I bet you just over torqued the rods with the higher boost at lower rpm. Sounds like a great excuse to put good rods in it next.

02PRUV

I was thinking this as well. When the 2 step is active the loads would be a lot less than any other time but as soon as I drop the clutch it gets all that timing back and it never would of seen 10 psi out of the hole in 1st before. So I found the limit of the rods.

Don't get me wrong guys I wasn't blaming the 2 step in saying it broke the engine I just wanted confirmation I wasn't going crazy with my diagnosis and just wanted answers like this one to confirm.

Just so you all know too plugs came out in perfect condition, pistons looked in perfect condition and bearings were perfect as well. So all I was thinking of doing was some 9.0:1 comp pistons and some h beam rods and go again. Should be all good.

gnx

yeap sounds like a good plan after getting the correct info.sucks that it happend though good luck

Jason Haines @ LPE

I would agree with what several others have said. With the 2-step active your cylinder pressures will be less than what they would be under normal combustion so this would be very unlikely to cause any engine related damage. If the unburned fuel from the deactivated cylinders does ignite, it does so in the exhaust. If enough accumulates and combusts it can damage exhaust system components (mufflers etc.). This is the reason for making sure you don't stay on the 2-step for too long especially if you have a full exhaust on the vehicle.

The highest combustion pressures occur under knock (detonation) or pre-ignition (not the same thing). Even stock engine components will survive fairly high boost levels in drag race type conditions with proper combustion. On the other hand even forged pistons and other increased strength components will not survive very long under improper combustion.

I would recommend making sure you didn't have too lean a mixture, too much timing and/or not enough octane. Those are often the first causes of these types of problems and could save you from the next rebuild.

02PRUV

Thanks for the reply Jason. This engine was running fine before the 2 step install. It has also been running E85 since it was turboed. So octane and timing wasn't an issue. Every other item that come out was also in perfect condition with no signs of detonation.

In saying this do you believe that the boost being forced in early with the 2 step then dropping the clutch there was enough extra force on the rods compared to not using the 2 step?

blackonblacksls

iTrader: (1)

I remember a couple of knowledgable guys talking about how starting a dyno pull too early would bend Rods in a stock motor. And they referenced how the 1200hp hotrod 4.8 met Its demise because of a single pull started earlier than the rest

Jason Haines @ LPE

Just making my recommendations on things to check to make sure nothing gets damaged and your vehicle runs properly. Not blaming anything in particular for what happened to your engine. Diagnosing a failure is hard enough with the parts, pieces and data in front of you, let alone over an Internet forum 8-) .

One thing to be careful of is that E85 fuel from the pump can change in octane significantly. To further complicate things pump E85 isn't usually really E85 because they have to dilute the pure ethanol itself with gasoline prior to transportation so that it can't be consumed by humans so the 85% ethanol used to mix with the 15% gasoline isn't pure ethanol to begin with. Also the summer and winter blends and the different regional blends change the octane level. Just something to be careful of when using pump E85 - always leave a little more safety factor in your ignition timing etc. compared to race gas that will tend to be more consistent in octane and other fuel specifications.

On an unrelated note, as someone else pointed out, where you make the boost can make a big difference on the cylinder pressures and engine durability. Your cylinder pressures are generally highest at your peak torque. More than one turbo race engine has been built smaller than the rules allow so that you can spin it to a higher RPM and make more peak power but actually have less torque down low in order to increase engine durability (assuming the rest of the engine is now designed to take the increased RPM).

Fbodyjunkie06

iTrader: (10)

Launched it off the two step at peak torque with 10psi on a 6 speed I take it right? Yea that's massive cylinder pressure city there.