Are you seriously going to argue that higher boost doesn't reduce longevity?

Dan

 

Sure will. At the levels you'll see on the street, you'll see no difference in wear. None.

How many boosted engines have you rebuilt? I've got 5 under my belt. 3 were stock, two were very not stock. The internals looked IDENTICAL.

Hell, diesels run 20-25:1 compression with 20 pounds of boost and last for HUNDREDS of thousands of miles between rebuilds.

 

I don't know much about cars but its common sense that the more hp an engine has the more stress on that engine. Boost increases power therefore there will be more stress on the engine. You can't argue that.

 

That says nothing without the mileage number. Were they rebuilt at 20K miles? 100K miles? 200K miles?

 

They were all fairly high milage. None of them were babied. They were all showing copper on the main bearings, they all had carbon buildup, and all of them saw some ovaling of the cylendars. But none of them failed - even the ones running higher boost than stock (two of them were GNs). In fact, they came apart looking identical.

Raising the boost in an engine (within reason, which is what we're discussing) typically won't change how rapidly it wears, especially if it's a daily driven street car. The percentage of time a car actually spends at WOT (when you'd actually see the added boost) is probably less than 5% of the total engine run time.

I love how people "hypothesize" about these things without having any actual experience, then spout off some "fact."

 

It's good to hear some first hand information; I'll keep it in mind if I ever get a FI motor, or add it to mine.

 

I really don't want to get into a long, drawn out debate with you about this.

Your first statement is just plain wrong. You'll see no difference in wear? Why do you think factories limit the amount of boost a turbo or SC is allowed to put out? Reliability is a big factor. Increased psi=increased pressure, heat, stress and wear. There is not way to deny that.

Take our cars for example(well, not yours), adding a SC or turbo is a big stress on our motors. Granted they weren't built for boost, but this is just an example. Even at 6 psi, our motors take a lot of stress from a SC. Up that to 8 psi and it's borderline destructive without any other mods to support it. So yes, boost decreased longevity in that case.

Now lets take a look at a vehicle that is designed for boost. Upping the psi from, lets say 11 psi to 15 psi is a big deal to an engine, but is easily achieved with a MBC(manual boost controller.) The car was not DESIGNED for this level of pressure and HP and it WILL wear more quickly than stock, given the exact same driving conditions, assumming that the driver gets to full boost once in a while.

As a mechanical engineer, who has worked for GM and designed powertrain parts, I can tell you that higher boost = increased stress = decreased longevity. It may not be enough for you to worry about, for the length that you plan to drive your car, but it is the truth. Go ahead an keep increasing the boost on your engine until it breaks, then tell me like you originally said, that you'll argue that increased boost doesn't decrease longevity.

By the way, why did your FI cars need rebuilds?

Dan

 

Raising the boost increases heat, which pushes combustion closer to the detonation threshold. Much more damage can be done in ONE 1/4 mile run with elevated boost pressures than 100K miles would do to a typical shortblock, so your "percentage" theory is of no consequence. And while I agree that if properly done , a reasonable increase in boost pressure would have little effect on wear since power loads typically don't stress a shortblock. Inertial loads do that and that is a completely different topic. But let's face it...we don't up the boost just to putter around town. Pushing the limits always puts you that much closer to the edge, and further away from the standard OEM reliability.

 

My statement is 100% correct. I've built these engines. Not theorized about them in CAD like you. I have real world experience rebuilding street cars and building race engines. Anything from your average 10 second street car to your 7 second SS/0 car.

They limit the amount of boost for a number of reasons, but I can assure you that on an SRT-4 (the car in question here) the engine was not the concern for limiting boost. It was the driveline they worried about (the stock axles are a known weakness). The stock block, crank, and head will support over 1,000 horsepower. There are NUMEROUS 425+whp SRT-4s on a stock engine, and guess what - they're lasting! (time will tell, but if an engine is going to go, it will do so pretty quickly. Ask me how I know)

Hmm. A 10.5:1 compression engine with powdered rods and hypereutectic pistons is stressed by boost?!??!?! NO ****!

That's where your wrong. The SRT-4 was designed for a high-horsepower application. It is very detuned from the factory. Mine has gone fatter than 10:1 a/f on the dyno. It's RICH.

That's great. What does GM have to do with the SRT-4? How much do you know about the engine in it? I'm guessing from your replies that the answer is little to none.

Because just like almost everything else I've owned, it eventually gets turned into a race car.

 

Big Red Jim,

You're loosing credibility with me Jim, but who cares. You obviously don't want to see things any other way than yours, even if it's the truth, so I'm stopping my discussion with you.

By the way, I listed my credentials because you seem to push it in other's faces that you have worked on FI cars. Who cares? That doesn't mean you know anything about longevity, just that you can repair broken engines, and build higher HP engines. Whoopie. BTW, you don't know much about engineering if you think that we sit and design on CAD all day, but that's another discussion altogether.

You don't seem to get the difference between longevity, and an engine withstanding mods. An engine can "handle" more boost, but will it just won't "handle" it as long. Like you said yourself, it's not just the engine you need to worry about, but all the parts downstream from the engine as well.

Take care,
Dan

 

Same could be said to you. Good night.

 

Attention Big Red Jim....your credibilty has just FLOWN OUT OF THE ****ING WINDOW......you show me a freaking NEON making 1000hp on STOCK, block crank and head and I'll show you a rolling ****ing BOMB......Seriously, do you realize the implications of what you are saying? There is absolutely no way this is true, and if for some strange reason there is a 1000hp neon motor I will GARUNTEE it will not last more than, lets call it, two trips down a quarter mile without seriously needing to be rebuilt.

 

I don't know if a stock Neon block/crank/rods can handle the power that Jim says it can, but if so, I think his point is that because it can, the difference between putting out 250 Hp to the ground or 350 Hp to the ground is essentially meaningless as far as the motor is concerned. IOW, well below its ultimate limit.

I've read articles about GMs Ecotec 4 banger putting out 1000+ horses, so why not a Neon motor?

 

It's unfortunate that you don't have a clue.

Get one. http://www.nhrasportcompact.com/2004...s_Carlson.html

Stock block, crank, and head. Well over 1,000hp.

Now go crawl back under the rock you came from.

 

Like is said...the engine in that car is REBUILT after every single run. The fact that the factory crank can "support 1000hp" is completely irrelevent, the rods will fail LONG before the stresses shear the crank in half, so that only leaves inertial forces acting on the crank, and if its balanced properly (which I promise you the crank in that neon is) (read:modified, as in, NOT FACTORY STOCK) the inertial forces can be minimized. Now on to the head....while the actual head itself may well be a factory neon head I promise it has been ported and given new valves (read: NOT FACTORY STOCK), and as for the block, its probably sleaved (read: NOT FACTORY STOCK), I feel like beating some common sense into your head with the "rock I came from".


BTW, your little link doesn't say one single word about stock anything nor does it say anything about 1000hp....try again chief