I'm asking this question in regards to my interest in keeping a reliable daily driver. What I'm asking is a 4G63 with upgraded pistons/ rods and built head going to be a dependable engine. I have personally owned 5 DSMs that have all been driven well past 100,000 miles with no problems, so I know that this motor is very capable. However, I've personally owned a DSM with a professionally built 4G63 that lost a rod at about 7,000 miles. This was only at 15psi on a stock turbo as I was breaking the engine in slowly for a large turbo. So my question is if I were to have an in chassis rebuild of my EVO motor at say 20,000 miles by Buschur, AMS etc. could I have a reasonable life expectancy of 80,000 more miles of use? Basically I'm shooting for a very reliable 350 whp motor using upgraded pistons/rods, a built head and cams. Feedback from Buschur AMS or any other engine builder would be greatly appreciated.

 

It depends on the parts used and the labor involved and the driving that is taking place. How did your last motor lose a rod? At idle? I doubt it. The tune running the motor also counts for a lot.

If the motor is built with strong, high quality parts, is balanced and blueprinted, is run with a proper tune, and is driven within its limits, it can last longer than a factory built motor. There are a lot of variables involved.

 

Engine reliability, especially a performance engine, are a direct result of the builder.. If their correctly built, and use quality parts that aren't potentially defective (Cryo treated, magnafluxed or x-rayed, and shot-peened, etc..), there is no reason why any engine can't last well over 200k miles, assuming the engine isn't abused in its duty..

If your HP requirement is around 350, these engines when properly tuned and upgraded will last easily last well over 100k miles if their maintained..

 

upgraded internals for only 350 whp? Unless you are winding it out to 8000 rpm all the time, shouldn't the stock bottom end be strong enough?

 

Your absolutely right.. but keep in mind it seems like he's looking for durability and longevity of the long haul, so I understand why he's asking these questions.

 

Thanks for all the infomative replies. As someone stated, the stock bottom end will easily do 350whp. One of my considerations was to have the head done and update with new head gasket, arp headstuds, and leave the bottom end alone. I always shift at 7000 rpms. I don't really find it that necessary to rev past this point on this motor. In fact, it is rare for me to run the car this hard as it only happens about once a week. I just want to know that I can use my car making modest amounts of power with no reliablity issues when I feel the need. I use my cars, I don't abuse them. I've driven plenty of high revving Hondas in my time that 8-9000 rpms really does not entertain me all that much. I rather enjoy the neck snapping power made from 4-6500rpms on these engines.

 

as far as long term reliability is concerned, you also need to take into account the material the pistons are made out of...Some aluminum alloys wear much faster than stock and arent designed to go 100k miles. Make sure you consider that.

 

I think you're concerned about the wear caused by piston slap during cold startups that are often assoicated with some aftermarket forged pistons. This will definitely reduce the life of your motor.

A stock EVO motor will satisfy your 350whp requirement though, so I don't really see why you see the need to build it up. "If it ain't broken, don't fix it."

 

I know that you can safely get 350 whp out of a stock EVO motor, but usually this is going to require opening the motor up and putting a set of cams and probably headstuds while you're there. I believe the jury is still out as to whether or not the stock springs can handle any upgrade of cams, including HKS 264s. It appears HKS feels it is OK to add their cams without springs and retainers, but I've read at least one person who has seen damaged valve seals on stock valvetrain EVOs with the HKS cams. I tend to err on the side of caution with everything I do. It is much cheaper to build right the first time than repeatedly fix crap jobs. As I reflect upon all the money I've dumped into cars, the ones that always seemed to work the best were the factory built motors with a few select, well-tuned parts. After spending $5500 to have an "indestructible" 500 hp motor built, that one failed, while my factory built 4G63 with over 150,000 miles and the original turbo for that matter continues to lay down a solid 275whp. I guess what I'm really asking is what is the best way to build a reliable daily driven EVO with 350 whp. It is starting to sound like possibly the best way to go is to just have a well done head with upgraded cams/springs /retainers and bolt that on to the stock block with ARP studs. Then have all this well tuned

 

Im curious also, cars that are putting down 500whp like AMS' car in Modified magazine, only has a freshened up head, head studs, a GT30 turbo and runs 28psi on race gas. Surelt that motors demise should be met at earlier than 100k. But seriously, with a conservative tune and about 400-450 whp on pump, with a good tune, the stock motor should be should for......? A built motor........?

 

I am sure you can get 350whp or more without putting cams, or even opening up the engine. Focus more on the bolt ons. I personally am waiting for Buschur's 20G. I am pretty sure that will put down 350whp on the stock motor. If you remember when Buschur was first starting out, when he first put on the 20G, the engine was pretty much stock, no cams, and he was hitting high 11's, or low 12's.

 

92Tsi, if you prefer to do the simplest thing possible to be more reliable, you should at the minimum replace the pistons. They are far and away the weak point in the motor. You will find that if you lose a piston, the forged, but thin rods in this motor will likely also break. If you can get the pistons to handle the power, the rest of the motor will be much better. I think that 350-400 AWHP is pushing the stock bottom end but if you put in forged pistons you can be a LOT safer without doing a lot more like rods, etc.

 

But then this brings up the issue of piston slap of aftermarket pistons during cold startups. Also the mention of the longevity of aluminum alloys.

 

Thanks for all the great information! Hopefully, Buschur or AMS will chime in as I would like to have their input since I know they have already built several EVO motors

 

I'm not sure why people think the EVO pistons are weak at the 400whp level. We shouldn't draw that conclusion just because one guy posts about his pistons cracking. We don't even know the root cause of his failure. There seem to be quite a few 400+whp EVOs on this board running on their stock bottom ends. If our pistons were indeed that weak, we would be hearing about more of them failing by now.