Street Build 7 bolt build

[cfal44]

I own a 97 eclipse gst originally had 120k on it and than i took a chunk out of the head, so i put a new motor in it and the timing belt jumped and bent my valves, i have a 7 bolt block laying around and i would like to build it to hold around 450hp, iv never built a motor before i was hoping someone can help point me in the right direction, im affraid ill invest the money and than at the end of the day the motor wont start, money isnt to much of an issue because im not on a time limit so i can buy and build gradually

 

[inthemidst]

I personally wouldn't trust a 7 bolt for more than 300 hp. I would get a 6 bolt for 450 hp its built a lot stronger.

 

[cfal44]

I personally wouldn't trust a 7 bolt for more than 300 hp. I would get a 6 bolt for 450 hp its built a lot stronger.

I wanted to do internals and all, so wouldnt the amount of power it can hold be based off of what parts i use to build it?

 

[inthemidst]

Yes if you use all forged internals sure it would help but first the oil squirter design is horrible and may be the cause of the notorious crank walk so I plugged mine. But for high horsepower engines you need the extra lubrication on the pistons. So you see why I said personally.

 

[CrackedDSM]

I personally wouldn't trust a 7 bolt for more than 300 hp. I would get a 6 bolt for 450 hp its built a lot stronger.

Yes if you use all forged internals sure it would help but first the oil squirter design is horrible and may be the cause of the notorious crank walk so I plugged mine. But for high horsepower engines you need the extra lubrication on the pistons. So you see why I said personally.

The oil squirter design is not the cause of the WAY overly blown out of proportion so called "crankwalk" and stock 7 bolts have been low 10's in the 1/4 reliably. Evos share the same rods, and just see what they can handle on a stock motor. The 7 bolt head is a better street/strip head by far as well due to valve placement relative to the ports and velocity, and on and on. People love to throw the crankwalk word around without actually measuring end play and verifying it's legitimately crankwalk and not a host of other problems, not to mention they usually rule out the possibility of user error. Built and high horsepower engines usually just delete/block off the oil squirters entirely, as it's a forged metal that doesn't need the assistance of the oil squirters to cool the piston like the stock cast pistons do.


The 6 bolt block is not made of some magic material that the 7 bolt block got screwed on. What a 6 bolt can handle, the 7 bolt can handle. Especially if we're talking about building it.


OP, just go with a stock rebuild. Read, research, read, research, and repeat that several times. Take baby steps, learn all you can, and take your time. I wouldn't go with a built motor just yet as it's not necessarily needed at this point, and don't even worry about making 450whp yet before you've even made 300fwhp. Take baby steps and learn all you can first. A stock rebuild is very easy to do yourself, especially if you read all the wonderful tech articles on here and the various other DSM forums, and if you take certain steps like ARP main studs, ARP rod bolts, ARP head studs and a decent headgasket, it'll hold very decent power.

 

[inthemidst]

From experience I had a friend of mine build a 6 bolt 4g64 out if a mighty max truck no oil squirter a come in that block with wiseco pistons and they got really scuffed up from insufficient lubrication so I got to disagree with you even though you may be right. But I like experience as my teacher.

 

[CrackedDSM]

From experience I had a friend of mine build a 6 bolt 4g64 out if a mighty max truck no oil squirter a come in that block with wiseco pistons and they got really scuffed up from insufficient lubrication so I got to disagree with you even though you may be right. But I like experience as my teacher.

It's all good. But one thing you should know is oil squirters don't lubricate the piston, they shoot a jet of oil underneath the piston to cool it. The only way it'd lubricate it, is if it somehow was able to shoot it up the walls of the cylinder which wouldn't be exactly a great idea. Our oil squirters literally do nothing but cool the stock cast piston, and possibly help the wrist pin, but on a stock setup the wrist pin is pressed in, so it's not gonna be doing any rotating like a free floating pin would in forged rods/pistons.

 

[inthemidst]

So you do agree that if you put forged floating wrist pins the lack of oil squirter a might cause a problem. I like your detail description sounds good and I agree with you.

 

[inthemidst]

Well I did some research on the 7 bolt squirters and they say they tend to get stuck open by such tiny particles that when you start the car the oil pressure shoots out of their instead of lubricating the crank and then little by little you start getting more and more play on the thrust bearing and vuahla crank walk . Does this sound right.

 

[CrackedDSM]

Nah, full floating pins found in a good set of forged pistons are made of a much better metal. They already get lubricated thanks to a pin-hole in the rod, as well as the bearing in the rod itself rides on a cushion of oil much like engine bearings do. If oil squirters were absolutely crucial you'd hear a lot of the big boys recommend it, but they just block them off and delete them. Even on a stock setup they aren't absolutely critical. The oil the wrist pin/rod needs, it gets from other sources.


To put it into perspective, imagine how fast a rod is going from 4,000-8,000 RPM. Imagine how blindingly fast that is...what happens if you squirt oil at it? It slings it off immediately. So squirting the rod or piston to lubricate it isn't going to necessarily work out. Does that make sense? This is also why the "lubricating the crank that causes crankwalk" argument is also a fallacy. Imagine the crank spinning on a lathe at 4000-8000rpm. Throw oil on it. What happens? You can imagine there.


The more life goes on, the more I'm convinced true crank walk is just a factory freak accident. True verified cases of non-user error and non-pressure plate related thrust bearing wear is less than 1% of all DSMs. The rest are, like I just said, because someone is an idiot and doesn't know to preload the crank while installing thrust washers/thrust bearing, or puts on a super extremely heavy pressure plate and rides that bish out.

 

[inthemidst]

But you just said the purpose is to cool the piston down which would explain why my friends pistons got scuffed up really bad higher heat more expansion from piston then it gets too tight to where their is no space for lubrication. Does that make sense.?

 

[d1prospect]

Everyone's story is different. I've ran 7 bolts in all my builds
without any issues. Quality parts and quality assembly.

 

[inthemidst]

Well you wanted a second opinion so

 

[mcraetim23]

I personally am starting a 7 bolt build and im shooting for 400+ hp going all forged internals built head 272 cams externally wastegated fp3065 not sure about injectors yet but im not a bit worried about the integrity of the 7 bolt engine

 

[BogusSVO]

Cast or forged, the oil squirters will be needed for some kind of endurance racing, where you have the max load placed on the engine for extended periods of time.

Like road racing.

With drag racing, being 15 seconds or less, not so much, but still nice to have.

Cast turbo pistons on the street, Better to have than not to have, but still not mandatory.

On the 7 bolts I build, the ones in the mains got to go, even with cast pistons, they rob flow from the mains and the rods.

@inthemidst ... I doubt your buddy's scuff pistons is from lack of lube, I have seen a scuffed piston or two myself.

Most the time it comes from to tight of a PTW, or trash in the oil, or the wrong oil being used, also possible is to lean of a tune causing the piston to expand further than engineered.

@CrackedDSM ... You have been on point with what you have said in this thread!!

 

[CrackedDSM]

@CrackedDSM ... You have been on point with what you have said in this thread!!

 

[estoyaqui30]

I think this 7 bolt thing is so overblown. I'm running a 7 bolt with original factory mains and thrust bearings. Eagle rods and Ross Pistons....375 AWD HP.....221,998 miles!