Stock Rod Limit

[JJ@WMS]

Thanks JJ.

Do you think this is the point where meth injection/ e85 is going to be necessary? Or is there some room for more power before we hit that ceiling?

Meth will help with cooling but most likely not with helping fuel the car. The reason is that your current fueling is done via direct injection at very high pressure so meth that is introduced into the engine wont deliver the same punch and the DI does. Meth might give a bit of overhead and safety but It wont be the solution.

IMHO the limit is sustained 25psi. Sustained 23 psi seems to be ok but at 25 your done.

JJ

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[TheZman]

I'm just curious as to what is the better car at $35k? Genuinely curious about that one. There's no doubt that the EB is a tremendous value, but many feel similarly about the GT given that both bunch significantly above their weight.

Im not commenting on the specifics or the nature of this post per say. But i think this price rang is going to be interesting in 2016 with the new Camaro coming and the new FORD Focus RS! The Scat Pack R/T is sort of an interesting choice around this price range as well..

 

[Barrel]

Im not commenting on the specifics or the nature of this post per say. But i think this price rang is going to be interesting in 2016 with the new Camaro coming and the new FORD Focus RS! The Scat Pack R/T is sort of an interesting choice around this price range as well..

Lots of ways to make speed. I only ask because I thought for weeks before my order of switching to the ecoboost just so I troll the streets with my little 4-banger. Tremendous value. In the end my emotions won out and I got the V8 sound and feel. But I never considered another car in the same price range that was as capable as a Mustang.

Can't wait to see what the highest HP EB will be on pump 93. Simply amazing.

 

[Anthony@HTM]

you are on the stock turbo/small AR housing pushing over 25psi.. your cylinder pressure and EGT was likely very high... a bigger turbo will allow for higher power/tq levels with less cyl pressure

Give this man a beer :cheers:

 

[TheZman]

Lots of ways to make speed. I only ask because I thought for weeks before my order of switching to the ecoboost just so I troll the streets with my little 4-banger. Tremendous value. In the end my emotions won out and I got the V8 sound and feel. But I never considered another car in the same price range that was as capable as a Mustang.

Can't wait to see what the highest HP EB will be on pump 93. Simply amazing.

I agree with you on the Mustang being the best in that price range! Obviously i bought one my self just a notch down in price range tho.. I understand with you wanting the v8 sound but a properly done up Turbo car all bolted up and tuned can sound pretty wicked just in a different way! So sound is subjective to what you like.. I like both.. One car you got a throaty v8 and in the other when properly done you got a loud whistling turbo and loud air bursts. Both sound cool in there own way! And as far as feel trust me a full bolt on Turbo will throw you back in your seat.. I had a 07 300 srt8 v8 and then got a 13 WRX. both fast but way different power bands. The 300 was power that just keep building till the car was going fast where the Tuned WRX would sneak up on you and throw you back in your seat right when the Turbo would kick in! The feeling a powerful Turbo 4 kicking in gets addicting after awhile and its pretty fun!

 

[Biffosaur]

No, I meant detonation that was not loud enough to be picked up by the driver.

Very cold temps and high boost levels have resulted in cars leaning out... as in the fuel pressure in the rail tanking. No fuel, lots of boost and high IATs can very well lead to detonation.

Mike

Is the cold just gunking up the fuel? Fuel pump crapping out at high flow demand under cold temps?

Cold weather should help prevent detonation, not encourage it.

 

[cosmo]

Is the cold just gunking up the fuel? Fuel pump crapping out at high flow demand under cold temps?

Cold weather should help prevent detonation, not encourage it.

Cold weather brings in denser air. Denser air essentially means more air. More air means leaner engine. Leaner engine means hotter temps along with increased chances of detonation.

EDIT: Also, colder temps reduce pressure, as in the fuel system. I doubt that has as much of an effect though.

 

[Biffosaur]

Meth will help with cooling but most likely not with helping fuel the car. The reason is that your current fueling is done via direct injection at very high pressure so meth that is introduced into the engine wont deliver the same punch and the DI does. Meth might give a bit of overhead and safety but It wont be the solution.

IMHO the limit is sustained 25psi. Sustained 23 psi seems to be ok but at 25 your done.

JJ

Gotchya. Seems like E85 and a larger turbo should help, along with a larger intercooler.


So...maybe this is out of the question...but does anyone have a flow chart of this turbo yet? Are you basing that 23-25 psi off your tuning experience or just the turbo/ engine size?

 

[arghx7]

you are on the stock turbo/small AR housing pushing over 25psi.. your cylinder pressure and EGT was likely very high... a bigger turbo will allow for higher power/tq levels with less cyl pressure

Just to build on this,

The mods are RIP Tuning intake, exhaust, and tune. (intercooler is in development) I had been pushing it hard since last Wed as we were getting ready to take it to the track. It made 420 at 3200 rpms, and 29.7 psi on MS101.

OP was running on race fuel. Race fuel allows you to advance the combustion more, resulting in higher peak cylinder pressures. These engine hard parts like pistons and rods are typically designed to a peak combustion pressure limit. The limit is specified in terms of an engine average combustion pressure of a number of cycles, and a max limit.

So for example, the 3.5L ecoboost is rated to 80bar max combustion pressure average and the full load curve reflects that:

Source: Kapp, "Ecoboost, democratization of sustainable engine technology," 2008

then the engine should be able to withstand a few cycles higher that, so if you're at 80 bar average you might be ok to 100 max on an individual cycle basis.

When you crank up the boost on a stock turbo and advance the combustion, your peak pressures increase. On a stock turbo you can expect more pumping work due to backpressure at the turbine housing inlet, and higher charge air temps due to running near the choke line on the compressor map. So the amount of combustion work to make the measured torque increase (you need more combustion torque to overcome the pumping losses and make more brake torque)

So 420 lb/ft of torque on a stock turbo makes the engine work harder than 420 lb/ft of torque on a larger turbo. Race fuel may reduce knock but it gives a false sense of security if you advance combustion to the point of exceeding rated cylinder pressures.

 

[sj90]

you are on the stock turbo/small AR housing pushing over 25psi.. your cylinder pressure and EGT was likely very high... a bigger turbo will allow for higher power/tq levels with less cyl pressure

I want to preface my post by saying I am looking for insight, not arguing anyone. (This threads gotten a bit hostile at times, I'd rather avoid stirring the pot) I know very little on the subject of turbo cars, so I'm trying to learn as much as possible.

Why would the size of the turbo allow the engine to withstand higher hp/tq? I understand why it will make more power with a larger turbo at the same boost, but I'm curious what the larger turbo does to take stress off the internals?

The only thing I can really think of is less back pressure from the turbo. Would that lower the losses of turning the turbo, leaving more tq at the flywheel? Or maybe lower the cylinder pressure because more exhaust gas can escape during the exhaust stroke? I know lower peak cylinder pressure helps avoid detonation, but that would be assuming that is what actually killed the engine, not just over stressing it. (I'm not commenting if I think that's what happened, I don't know enough to contribute intelligent input)

Edit: arghx7 answered a few of my question... I'm a bit of a slow writer.

 

[greg hazlett]

Don't our cars have knock sensors and if so wonder if they were turned off via the tune?

 

[mbreinin]

BGolden did not say if they were running additional timing. He was pushing almost 30 psi of boost, so it may have been just an increase in boost and not timing. These cars are in negative timing under boost usually....which also makes heat.

 

[arghx7]

I want to preface my post by saying I am looking for insight, not arguing anyone. (This threads gotten a bit hostile at times, I'd rather avoid stirring the pot) I know very little on the subject of turbo cars, so I'm trying to learn as much as possible.

Why would the size of the turbo allow the engine to withstand higher hp/tq? I understand why it will make more power with a larger turbo at the same boost, but I'm curious what the larger turbo does to take stress off the internals?

My post got buried at the end of last page but it explains it partly.

http://www.mustang6g.com/forums/showpost.php?p=479229&postcount=144

The only thing I can really think of is less back pressure from the turbo. Would that lower the losses of turning the turbo, leaving more tq at the flywheel? Or maybe lower the cylinder pressure because more exhaust gas can escape during the exhaust stroke? I know lower peak cylinder pressure helps avoid detonation, but that would be assuming that is what actually killed the engine, not just over stressing it. (I'm not commenting if I think that's what happened, I don't know enough to contribute intelligent input)

The torque you measure is the result of losses. On an engine dyno it's simpler because there are no drivetrain losses.

I take the torque generated by combustion, subtract the torque wasted on pumping air in and out of the cylinder, and subtract parasitic losses (friction).

When the pumping losses decrease through say a larger turbine hotside, I need less combustion work to make torque. Less combustion work means less peak cylinder pressures, generally speaking.

I'm explaining this in words because it is easier to follow for most people than equations.

 

[JJ@WMS]

Gotchya. Seems like E85 and a larger turbo should help, along with a larger intercooler.


So...maybe this is out of the question...but does anyone have a flow chart of this turbo yet? Are you basing that 23-25 psi off your tuning experience or just the turbo/ engine size?

You wont be able to go E85 unless the high pressure fuel supply issue is resolved so a larger turbo capable of more boost and power is a waste unless there is more available fueling.

23-25 psi limit is set due to tons of track testing and tuning. I know when these cars run out of fuel because I've proven it to myself on our own car.

IMHO a few bolts ons and a good safe 21-23psi tune will work wonders for pretty much everyone however if you want to push it further or go large turbo, big power etc... you will need to upgrade the rods and pistons.

There is a reason why companies are developing engine components for these engines.

JJ

 

[arghx7]

Don't our cars have knock sensors and if so wonder if they were turned off via the tune?

The knock sensor signal processing probably wasn't set at Ford for that kind of load on the engine, meaning it could be too sensitive or not sensitive enough ie it's useless under those conditions and OP can't be faulted for turning it off or ignoring it, or not seeing any knock from it.

BGolden did not say if they were running additional timing. He was pushing almost 30 psi of boost, so it may have been just an increase in boost and not timing. These cars are in negative timing under boost usually....which also makes heat.

Spark timing is not combustion phasing. The timing doesn't tell you how fast the mixture is burning. You can keep the timing at -4 degrees and still have more advanced combustion if the combustion speeds up for whatever reason. You can't tell that without cylinder pressure indication. Only Ford and its development partners have cylinder pressure indication equipment and engines tapped for indication probes.

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