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Old 04-12-2009, 12:44 AM   #1
mystilexzero
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Default to the engine builders, blueprinting necessary?

So i went to GST motorsports, the people who made the subaru on the cover of modified magazine in the tuner shoot out to get some recomendations on my build, they sent me to their shop that does all their machine work and has done subaru's since 2002, as i dropped off everything he gave me a qoute which included the following:

Engine bore and hone
crank cut
balance and rotating assembly
decking of the block
and of course a clean job

and thats about it, i said no when i wanted him to assemble the motor because i plan on doing it with a few people in my area who build supra's and dsm's. However i asked him about blueprinting, i read countless threads of people doing them on this forum, as i tell him he simply says "its not for you"

he says blueprinting is for drag cars, cars running 30+ pounds of boost made solely for top speed, and with my application, which is a 2004 sti block with wiseco pistons, eagle rods, acl race bearings .25 over it wouldnt NEED blueprinting.

the reason why i post this thread isbecause the main anwser to everyones questions is simply "ask your builder" well i did and it worries me a little, i can still go with blueprinting but when someone who builds 400+ whp subaru's all day tells me i dont need blueprinting it confuses me thus i would like to know what some of you other engine builders think.

thank you for your time and concern, its very much appreciated.
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Old 04-12-2009, 01:00 AM   #2
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Balancing the engine is definitely something you want to do. Less wear at high rpm, smoother revving engine, etc..
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Old 04-12-2009, 01:29 AM   #3
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Blueprinting is for anyone who wants to do 1 of 2 things.

(1) You want to build the engine EXACTLY as the manufacturer intended it to be built, adhering to EVERY single specification and tolerance as outlined in the service manual - - - - You are building it to THEIR "blueprint"

(2) You are building the engine to YOUR specification (or someone else's) and you want repeatable results as you build additional copies of that engine per the "blueprint".

Either way, you should create a build sheet, and mark every single detail on that sheet as it pertains to clearance, tolerance, flatness, surface finish etc.

Anything short of this is you just putting an engine together and guessing at what are essentially life or death (of the engine) specifications and more often that not, death is the outcome.

Even if you use a majority of Subaru's spec's during the build, you may in fact use for example looser crank/bearing clearances or tighter piston to cylinder wall clearances based on recommendations from piston manufacturers or vise versa, none the less you have modified the original blueprint and need to create a new one.

The reason this all becomes vitally important is the day will come when your car hits the (dyno) rack and and your tuner may (should) want a lot of this information, and if you whip out your build sheet (blueprint) and hand it to him, he will know how far or hard to push getting you the most power safely.
And you wont be regurgitating numbers from memory days weeks or months later.

You cannot just assume that the shop that dressed up your bores and decked your case(s) and heads did it properly, you need to check all of that stuff yourself if you are the builder, As an Example, Subaru allows you to remove .004" (4 thousandths of an inch) from the deck before they want you to buy new cases, and .0012" (a little over 1 thousandth of an inch) from the head mating surface before they are beyond the tolerance of the "blueprint" (service manual).

When you take parts to the machine shop, show them the service manual or at least go with a list of allowable toelrances for EVERYTHING they are going to touch.....do NOT just walk in with a bucket of parts like your heads and say "will you do a clean up pass on these for me" what you may end up with is .010" removed from your head which changes a lot of things down stream, quench, compression ratio, valve to piston clearance etc.. come to mind.

SO you can see how important this stuff is.....others may not think this is as important as I do, but that's the way I am going to build my engine(s).

Last edited by Team Scream; 04-12-2009 at 02:43 PM.
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Old 04-12-2009, 08:24 AM   #4
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very nice information, i guess ill have a talk with them next week, they arent starting till teusday so if anyone has anything else to chime in it would greatly help.
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Old 04-12-2009, 06:26 PM   #5
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Just like team scream said blueprinting is if you are going off specific specs.If you assemble the motor properly you will be double checking all the clearances before assembly which means you are basically blueprinting your motor to your own specs.
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Old 04-12-2009, 07:14 PM   #6
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You can use the spreadsheet I just created if you want to.
Check out this thread: http://forums.nasioc.com/forums/show....php?t=1741302
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Old 04-13-2009, 05:40 AM   #7
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Quote:
Originally Posted by john 1badSTI View Post
Just like team scream said blueprinting is if you are going off specific specs.If you assemble the motor properly you will be double checking all the clearances before assembly which means you are basically blueprinting your motor to your own specs.
thats a really nice way to put it, after reading more threads it seems that blueprinting is exactly that, so in theory everyone blueprints when they assemble their motor, yet i think there is a more in depth way of blue printing, or so my machinist explained,

blueprinting can also involve measuring the distance each piston travels to ensure all cylinders have the same compression, and tbh i forget the rest he was explaining to me, i was already lost after that.

I know its wrong to ask questions like "would it help my motor last longer" as its as if comparing to a person with cancer "will this medication help me live longer" but i was wondering if some people can voice their opinions is a full blueprint is necessary for a street build that will most likely see a blouch dom4 or atp gt35r on 25 psi in a few months.

The cost isnt really an issue at this point, its just figuring out if what my engine builder said was true where "its simply not for you just yet"
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Old 04-13-2009, 01:06 PM   #8
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Quote:
Originally Posted by mystilexzero View Post
but i was wondering if some people can voice their opinions is a full blueprint is necessary for a street build that will most likely see a blouch dom4 or atp gt35r on 25 psi in a few months
This statement answers your question completely (if that makes sense).

You are taking about an engine that will see cylinder pressures, torque loads, heat loads, rpms that are far higher than it was originally designed to handle.

Now, if you are using stock parts in this build you can be reasonably certain that the sum of those parts passed the quality control processes on the line they were produced which should in theory put them within the specs ("blueprint") and tolerances set forth by Subaru.
What you cannot control is the overlap of tolerances without careful measurement.

Picture this as an example:
You have a crank which was machined to the large end of the tolerance allowed for the big end rod journals.
Next you get a set of rods that was machined at the tight end of the tolerance allowed.

You put these together and you end up with less rod to journal clearance than is safe to run (especially at higher loads and rpm) and you have a recipe for disaster.

This is just one example.

You cannot (well you can but you shouldn't) just put parts together without checking everything meticulously.....you will end up doing it twice (once the engine blows).
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Old 04-13-2009, 06:04 PM   #9
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If you tell Mike where you want to get to, he will help you get there.

My take is that he (Mike or the Machinist) is giving you the benefit of his expertise and trying to save you a few bucks on your build. Given that you are doing the assembly yourself, cost savings is an easy
assumption (to me at least).

Bottom line? If you would feel safer with blueprinting, go for it. Otherwise save the cash for your gasket kit, water pump, oil pump, etc.
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Old 04-13-2009, 09:09 PM   #10
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Quote:
Originally Posted by aboothman View Post
If you tell Mike where you want to get to, he will help you get there.

My take is that he (Mike or the Machinist) is giving you the benefit of his expertise and trying to save you a few bucks on your build. Given that you are doing the assembly yourself, cost savings is an easy
assumption (to me at least).

Bottom line? If you would feel safer with blueprinting, go for it. Otherwise save the cash for your gasket kit, water pump, oil pump, etc.
your right he is trying to save me money, however i do have all the parts, gaskets and everything, im thinking i might as well do blueprinting, theres no point in doing it twice like what team scream said. i believe it defeats the purpose of having a "built" motor, its made to perform and last through harsh abuse, and i shouldnt have to worry about it, thats the main reason why im building this motor anyway, so i wouldnt have to worry about spinning bearings and blown ringlands. thank you for all the help, i think i just anwsered my own question
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Old 04-13-2009, 11:09 PM   #11
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Heres the dealio bro,

The most important things to have "blueprinted" are also among the things that should be done regardless of who is building the engine.

Once you get your block apart have your machinist do the following:
Bolt the block back together without the crank or bearings in place.
Then have him use a calibrated bore gauge and measure the crank main journal bores.
Have him check the journal alignment to determine if you need an align hone or a bore or just leave it alone (if it is good).

Then have him mic the crank with a calibrated micrometer.
Is the crank good and within spec (rod and main journals)?
If Yes: have it balanced with the rest of the rotating assembly, polished and leave it alone.
If No: have it machined as required or buy a new crank.

If you are having the crank machined, get the right (undersized) bearings required (rod and main journal) and have them checked in the bores BEFORE machining the crank, if the crank is to be machined, the machinist can polish the journals to achieve uniform clearance between ALL bearings when they are in the crushed state.

Check with the bearing manufacturer you are going to use, and find out if the bearings you choose will fit properly in the journals (including the crush dimension) based on your machinists findings (rod and main journals).

Your machinist will now place the new bearings in the bores and measure the crushed dimension with a bore gauge, he will compare those dimensions with the measurements from the crank and determine how much measured clearance there will be for each journal.
If he is anal, he will qualify this with plastigage as well to be certain.

He should then qualify the crank thrust (side clearance) dimension, and rod side clearance dimensions.

He will follow the same procedure with the rod journals and bearings, after he has determined the rods to be within spec.

That gets the crank and big end of the rods out of the way.

Next step will be the cylinder bores and pistons.
You will hand him the pistons which have already been balanced with the rest of the rotating assembly (or not) and he will mate the pistons with the bores they most closely match so that when they are bored or honed, he will remove the least amount of material possible for each one.

The bores will be machined to the clearance you (or the piston manufacturer) specify getting the piston to cylinder wall clearance out of the way.

The rod small end, and wrist pin dimensions will be verified, and if you are re using your old rods, it may be necessary to have new bushings pressed in and honed to size (wrist pin dependent).

This pretty much covers what happens when blueprinting the short block aside from the head mating surfaces as far as machining and clearances are concerned.

Once the rotating assembly (sans the clutch and flywheel) is together, deck height is measured and noted which will be necessary when calculating compression ratio and verifying piston to valve clearance.

The same attention to detail should be paid to the heads in my opinion, measure the cam journal bores, the cam bearing surfaces, and use plastigage like the service manual suggests to determine cam to journal clearance.
There is also a cam side clearance tolerance that should be adhered to.
Finally measure the cam follower bores and the follwer's to make sure they are in spec, too much clearance affects oil pressure in a negative way, so those tolerances are there for a reason.

Beyond that, the rest is compression ration related, swept volume,compression chamber volume, gasket volume, dish volume, deck height, quench are all very important parts of the blueprint, and if you dont know how to get there, let someone who does, do the work.
Finally, valve to piston clearance, and valve lash clearance are blueprinted.
If you have the gauges, mic's, magnetic bases and all the other neat stuff required to put a top end together "PROPERLY" then by all means do it, it is incredibly rewarding when it comes out good and big power is made.

Again, and I will repeat myself for posterity, "anything short of that, is just you slapping parts together".

Last edited by Team Scream; 04-13-2009 at 11:25 PM.
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Old 04-14-2009, 03:11 AM   #12
mystilexzero
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wow theres definately alot to blueprinting the shortblock, looks like ill have to goto the machine shop and verify with him what i want done for blueprinting.

on a side note, yes my crank is being grinded down but dont i need oversized bearings to make up for the lost space? you stated if my crank was grinded down i would need undersized? im just clarifying to make sure i got the right part, i got acl race bearings ten thousands of an inch bigger (.25mm over).

thanks again everyone for your help, im sure this engine will be running healthy
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Old 04-14-2009, 04:04 AM   #13
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Yes the bearings are technically oversize. BUT, the crank itself was machined undersize, hence the term undersize bearings.
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Old 04-14-2009, 05:23 AM   #14
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oo gotcha thanks for the clarification!
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