babaz7

how reliable will be a 500whp built motor and how many miles should it last?
anyone who has this kind of power please comment on how many miles you are at this level or how many miles after you rebuilt it?

LetsGetThisDone

iTrader: (1)

It's impossible to say. It depends on how you drive it and how it's taken care of.

KingTal0n

It has less to do with the power

and more to do with the machine shop, machine work, maintenance, attention to detail, quality parts and careful considerations.

All it takes to ruin an engine is a tiny grain of sand-size particulate clogging an oiling orifice somewhere,
easily these granules can be introduced through careless handling of parts or poor machine work.
For example if you open the oil cap to do an oil change (A fairly routine, non-invasive process) but a tiny bit of dirt falls from your hands into the engine.
It would be extremely lucky if the filter caught it after circulating for a bit. However more likely it will get caught up between two metal parts and smashed/permanently embedded somewhere, or worse caught in an oiling orifice.

Now just imagine somebody with no gloves actually taking the valve cover off. Or the head. Or the timing cover. Etc... getting dirty filthy fingers inside the engine and putting it on machine shop equipment without proper cleaning or attention to the smallest particle. There are miles and miles, hundreds thousands of people on the internet having these sort of machine shop related issues if you search around.

And this is just one of the minor issues that crop up when building a motor, the smallest most insignificant issue in the back of anyone's mind is typically cleanliness when doing these things. For some reason they seem to think the motor will be "Clean" if it looks "clean" when in reality it can be washed, soaped, scrubbed, brushed, and still not be truly clean.
Another issue is the wear and tear associated with larger than factory clearances, which acclerate wear and tear. For example typical low silicone forged pistons have a large piston-wall clearance, so when the motor is started cold the pistons slap around in the bore enough to excessively wear the cylinder walls in a sort of egg shape pattern. If the motor is constantly cold-started and run like that, especially run hard, the wear is accelerated even further.
And many people do not realize how long it takes to warm pistons like that up. It could take 20-30 minutes of medium-pace driving (pre-laps around a track). So I don't recommend a much larger piston/wall clearance than OEM if the vehicle is a daily driver, or not going to be run sufficiently long to fully warm up each time it is turned on.
And finally there is the issue with poor machine work. Even if everything is done cleanly there is always a chance the built engine could be built wrong, and perform worse than factory.

Some examples from around the net:
1. 2.0L Engine failures mostly related to poor machine work
https://zilvia.net/f/showpost.php?p=6285960&postcount=4
https://zilvia.net/f/showpost.php?p=5837231&postcount=7


2. Not happy with built engine
"I hear ya! Had more trouble with machining BS trying to use aftermarket parts than I care to admit. Wish I would have stuck to factory short blocks as well. Tired of pulling apart "built" motors when guys are making twice the power on factory original stuff and racing the whole season."
http://ls1tech.com/forums/forced-ind...l#post19525070

3. built motors dont last in this car community
https://www.corvetteforum.com/forums...-blown-up.html

4. Don't rebuilt that engine!
https://www.yellowbullet.com/forum/s....php?t=2401762

5. Stock is Reliable
https://www.corvetteforum.com/forums...2&postcount=63

6. machine work screws you over most of the time
https://www.yellowbullet.com/forum/s...2527749&page=8

Note:
I see many successful 4g63 (and similar) builds so it is certainly possible. My warning is merely universal caution, i.e. too many tales of improperly assembled or machined engines out there not to make warnings.
What you need to find is a place that does the same builds, over and over, for the last 10-20 years and has it down like a clockwork. I think it is perfectly acceptable and even possible to properly build an engine once years of experience and success is on the table, confidence would be much higher in survival rate. Be cautious of anybody that claims they can rebuild an engine without a track record of doing so, and caution of anybody who doesn't wear gloves or mention how clean is so important in these details.

kikiturbo

1. Cylinders do not wear from cold pistons "slapping around"
2. OE cylinders are oval when the engine is built up from the factory
3. it takes much less than 20 minutes to warm up the pistons
4. PTW is a factor of piston material and intended use
5. I know it is popular to say that OE is best but some of you guys just take it to the extreme... Cant have a 500 WHP engine in stock block if you want to use it properly... There is great deal of experience with running Oe engines in competitive environments at 300 hp at crank and lots of torque (as much as stock turbo will push out) and those engines last about 1500 competitive km before the rod breaks.. Super high power OE blocks that people run in the us are sort of ok because of too large turbos that spool late and the fact that they are mostly run at full power very rarely.. like a 1/4 mile pull and then long cool down.. However, 500 whp stock block is running on borrowed time..

KingTal0n

You are speaking of specifically 1 engine.
My passage is directed for ALL engines, as a general statement.

1. cylinder wear like engine wear anywhere else is increase when clearance is increased, that is a typical relationship, new engines have the tightest clearances and the thinnest oils for maximum mileage.
2. for your 1 specific engine maybe
3. It takes longer than you think combined with oil warming to approx 200*F it can take well over 30 minutes for daily drivers to reach a high enough temperature anywhere satisfactory for performance at redline.
4. intended use being the key, since I refer strictly to daily drivers which want tighter PTW clearances for wear/tear reasons
5. There are many 500-1000rwhp OEM engine variants that cost $1000 for the engine or less (LSx variants) and more expensive OEM platforms good in that range (2jz).
You are talking specifically of one narrow brand of OE engines whereas I speak generally for all engines

LetsGetThisDone

iTrader: (1)

An engine is an engine for the most part, so because it's a different engine doesn't change the low temp wear characteristics too much to be worth talking about.

We're on an Evo forum. This is a specific discussion. Do not make generalized comments and statements.

My oil temp is 150+ within 10 minutes of driving even when it's cold out.

RazorLab

iTrader: (8)

20-30 mins to warm up a piston? Lmao

KingTal0n

You can drive a car for an hour in traffic and still not fully expand a set of forged pistons.
You can drive a car every day to and from work and never fully expand ""

Heres a sort of example I came across at random:
https://www.evolutionm.net/forums/ev...problem-3.html

He had the motor built and drove it for a while easy. The pistons never fully expanded in the bore after many miles and hours of run time iirc.
Then finally he let the engine go WOT and they fully expanded, seized in the bore and broke the motor.

I also have an engine here with CP pistons 2.0L and it takes EGT>1000*F to fully warm the pistons, that is some time at WOT with low boost before using high boost it requires.
You can tell when the piston fully warms because the crankcase pressure log shows a marked drop in pressure during on-throttle situations, especially WOT, leakdown decreases (blow-by decreases) and it shows up on the crankcase pressure gauge (log).

So I would say you guys never utilized a crankcase pressure log to determine pcv performance,
and never took apart a factory engine after 250,000 miles and compared it with a forged motor after 20,000 miles which was used for cold-start driving (< 40 minute from start to shut down)
The increase in bore wear over such a short time is significant.

From the thread:
I.e. the pistons never fully expanded in the bore during the 600km of driving that was done.
Only once it was finally turned up in power (1100*F+ EGT IMO) did the pistons finally expand.

Biggiesacks

Just to echo LGTD here, it all comes down to intended usage. A 500hp race engine is not built the same as a 500hp street engine. Getting higher level, the cooling system/strategy for a 500hp race car is not the same as for a 500hp street car.

KingTal0n

I do not believe a metal ever stops expanding. If we continue heating any metal , I think it may expand until it melts, and even continues afterwards to expand as a liquid? I never thought of that before, but the equations used to determine the length of rods or expansion is a cylinder just have variables, which could be any number.

So I think the maximum piston size is calculated (which requires the highest temperature it will ever see) and that sets the PTW clearance.

The less rate of expansion (cast pistons expand less for the same temp increase) means the starting PTW clearance can be less, giving good sealing at low temperatures.

The EGT reflects temperature range of "whatever is going on inside the combustion chamber" i.e. If we use EGT as a poor indication of how hot the piston is likely to get, then we can use a comparison such as this:
Cold Start EGT range (80*F-200*F) The egt can hover in this range, especially in cold climates, for several minutes after a cold idle startup.

Warming up EGT range (200*F-450*F) The vehicle is driven normally perhaps in traffic (cast piston, tight clearance application) or at a low-medium rate around a track (forged piston application) where stop and go, and clutch use is minimized to keep the rotating assembly arbitrary excess cold clearance settings, wherever there are any, from creating unwanted additional wear and tear while it warms up at a steady rate. The length of time spent in this range depends how the oil cooler/capacity/thermostat is setup, as some engines can forced to warm up more rapidly than others through creative techniques. The daily driver cast piston applications that spent 5 minutes in the Cold start range (ambient around 80*F) using factory thermostats and oil capacity will likely spend approx 20-30 minutes in this range, but the oil temp may not be fully warm for 30-40 minutes.

Approaching max output EGT (450*F - 1000*F) The engine can be run at WOT once oil temperature is in the range 200*F+ depending on oil/climate (for cast piston application throughput e.g. lower power output than forged pistons would see, for 2.0L engines this is typically around 400hp at least it was for many engines made before 2004) or the engine is run at medium boost levels (forged piston application, still technically warming up)

Max output, general EGT gasoline (1000*F-1500*F) Cast piston applications typically recommended to stay under 1300*F, whereas forged piston applications can see 1600*F some places. It is in this range that the manufacturer likely finds and sets the piston size and recommended piston to wall clearance PTW. Much higher in temperature and the piston rings suffer lost tension and the engine will begin to blow oil. Water injection can be used to limit EGT and it is recommended for the majority of gasoline applications, especially those using tight piston ring gaps as water helps control thermal expansion which keeps the ring ends from touching.

LetsGetThisDone

iTrader: (1)

Metal expands a certain amount per temperature.

You're way over thinking. There's built engines that are well built and taken care of and have gone 100k miles. Beating on something like an Evo at the 500hp level I'd expect it to need rings at 40-50k miles. Cast vs forged isn't the primary issue, it's the alloy. Example, Mahle makes 4032 forged piston that can be run at clearance of 2-3 thou.

Cast pistons can certainly handle 1500-1600* EGT. They do it in a stock 4g63.

You're way over thinking this based on a bunch of people who worked with **** machinists and most likely had **** engine building skills or a **** engine builder.

OP had a simple question about reliability and you're bringing in engine building theory that has no real relevance.

Will a built engine go 200k? Probably not. But most stock Evo's never went that far either. 40k-100k miles is a realistic expectation based on proper maintenance and care. With variable being how it's driven.

xRoguex

iTrader: (15)

My fully built 2.4 went 35,000 miles and i only pulled it because I had the opportunity to refresh it and go for bigger numbers.

KingTal0n

I agree with everything here except that obviously theory relevant to the application and alloy selection which is often overlooked in backyard builds which I why I brought it up, not all material is made similarly and some forged materials are not suitable for daily driver applications

I know the 4g crowd has a higher rate of success this was just general tips for keeping out of bad habits

And finally, wow 100k max from new cars? Thats harsh. 4-cylinder sr20det frequently go 250,000 miles same displacement 350hp~ cast piston engines

LetsGetThisDone

iTrader: (1)

The 2618 alloy still does fine. That's the only two alloys commonly available. And 4032 isn't even common.

I didn't say 100k max for a stock one.

A lot of stock Evo engines get pushed very hard. Upgraded turbo, 400wtq which is the limit, 5-600whp. Drag racing, road course, autocross, all of that.

Biggiesacks

Our 4g63t's also have oil squirters to help cool the pistons.