greenbluewoo turbo build ''list''

[daewoomofo]

@ chris, i refurbish landing gear for aircrafts. im faa certified, and im accredited to sign off on AFRTS (approval for return to service) documents too.
the problem i have with bore guages is that you dont know the actual size, it will give you a difference from a set point, but it doesnt tell yo the exact size. a digital would be easier to use since you can see exactaly where it maxes out at and size that with a mic, but analog ones are a bitch to use. what i like about the snap guages is that you can size it to the bore and then remove it, with it keepig its size, with the bore guage its kinda up to how your looking at it, if your not dead on your readings can be off too. the snap guage is cheaper too, but in the end its totaly up to greenblue. if it was up to me, id use the snap guages, or have a reputable shop size it for me.

[PrecisionBoost]

I didnt measure the bore but I bought the motor brand new only had 55 miles on it so I thought it would be ok since I bought the same size pistons as stock I will go and get the bore measurement tool check everything out oh and the rust on the side of the motor wasnt there when I got it. its because it was sitting in my garage for a year

Ok.... so your going to be fine for runout and out of round because it's a brand new engine.

You could get away with simply using a nice digital micrometer ( which will be usefull for other things )

I have one of these digital micrometers in my work shop for everyday measurement so I don't damage the Mitutoyo unit I have for QC.... they work decently.

http://cgi.ebay.com/6-inch-LCD-Digital- ... 7C294%3A50

For those who read this and have older engines..... you take a very precise measurement at the top of the cylinder.... put in your bore measurement tool..... zero the gauge and use the gauge to give you a +/- from the original measurement.

So.... for example.... lets say your doing it in metric.... and you measure the top of the bore as 86.025mm.... then you put in the gauge and zero it at the exact spot you took the measurement.

Then you can rotate it around and go up and down using 86.025mm as the gauge reference.

[PrecisionBoost]

Did you get a specification sheet with your wiseco pistons?

That should state the recomended piston to wall clearance.

Wiseco says to measure their piston diameter at the widest part of the piston skirt 1.300" down from the bottom of the oil ring groove

I'm guessing the spec sheet will recomend 0.004" clearance... or perhaps even as low as 0.003"

You allways have to measure at the skirt because the top will be smaller in diameter.... as it gets hotter ( thus expands more )

Basicly they design the piston so that the expansion will be linear once the piston is hot.... top is smaller but expands more... the skirt is larger but it expands less.... so it all equals out in the long run.

So.... 86mm = 3.386" ..... if that happens to be the width of your pistons then you need to ensure that your cylinder bore is at minimum 3.390" wide ( for 0.004" clearance )

This equates to about 0.10 mm clearance.... so 86.1mm

Even the factory engines have a tollerance..... so who knows.... you might get lucky and not have to do anything.

The older forged pistons were really bad.... they needed 0.009" of clearance typcially.... which usually meant that you ran into issues.

I don't think I've ever heard anyone going less than 0.003" clearance on a forged piston..... and I think 0.005" is common on some of the big bore pistons.

Hopefully (cross your fingers) you got lucky

[PrecisionBoost]

Here are the specifications for the U20SED......

Cylinder Bore Taper - Maximum
0.013 mm
0.0005 in

Cylinder Bore Diameter
85.975-86.025 mm
3.384-3.386 in

Cylinder Bore Out of Round - Maximum
0.013 mm
0.0005 in


Piston Clearance to Bore
0.010-0.030 mm
0.00039-0.0011 in

Piston Diameter
85.955-86.485 mm
3.384-3.404 in

Maximum Piston Protrusion
0.5 mm
0.019 in

Piston Taper
0.013 mm
0.0005 in

So as you can see..... the factory pistons have a clearance that is 3 to 10 times less than a forged piston.

Given the factory specs show 85.975-86.025 mm / 3.384-3.386 in as maximum cylinder bore that may mean your out of luck if your Wiseco pistons are exactly 86mm.

Lets hope they are actually 85.9mm because that would give you the correct 0.1mm clearance required.

If you have the spec sheet for the pistons.... can you post the info... or scan it in?


While we are on the subject.... if you purchase a micrometer you should measure the protrusion of the piston above the deck ( pistons allways stick out just slightly )

The factory spec is 0.5mm which seems reasonable... but you should definitly check that while your doing the other measurements.


So at this point.........I suggest buying the micrometer and taking measurements of your bore..... the key number is the bore diameter from back to front of the engine because that is where the piston skirts are located ( so if your standing in front of the engine by the exahust manifold your measuring the bore at 90 degrees to the manifold.... front to back.... right to left should also be measured but it won't be as critical )

[PrecisionBoost]

Oh..... just so we are clear..... I'm not trying to freak you out.... I'm just telling you how things should be done..... it's concievable that you could put this engine together as it stands and get tens of thousands of miles out of it without a problem..... but if your going to all this trouble and money you really should make sure it's assembled with precision.

[greenbluewoo]

my scanner isn't working but it says on the spec sheet that the bore size is 3.3858 this is measured at lowest point of piston skirt, or 1.300 from bottom of oil ring and it said suggested clearance is 0.0035 and the weight is 328.9-329.4 grams but will get a pic of the spec sheet tommorow

[greenbluewoo]

oh and precisionboost I know your not trying to freak me out.. your just trying to help and I really appreciate it and how is the gsi project going its one of my favorite builds I probally read that thread 5 times

[PrecisionBoost]

That sucks.... I made this nice long post with technical info and the system locked up and I lost the post info

I guess I was pretty close with a guess of 0.003" to 0.004" as your spec sheet data is right inbetween the two.

So..... basicly the end result of calculations I made in my first post is that your pistons are exactly 86mm so you will most likely still need to remove 0.0018" to 0.0040" of material from the cylinder walls depending on the my estimates of the current bore diameter.

That might not sound like much but you have to be carefull of how you do this.

If you use a simply cylinder hone then it's possible that the cylinder diameter will not be the same from top to bottom.

That is to say you might remove 0.0015" from the top and bottom and 0.0030" from the middle ( which tends to happen unless your very careful and take measurements as you go along )

Given the maximum taper of the cylinder is specified as 0.0005" this type of scenario would equate to nearly three times the amount of allowable taper.


All I'm getting at is that people don't normally remove this much material with a standard hone.... quite often they use machines to do it with diamond grit... then finish it off with a fine grit.

Because the speed and angles are controlled by the machine and it's a precision hone they are able to do it very accurately with next to zero cylinder taper.


Don't get me wrong..... you might be able to do it yourself..... but it's a risk you take in doing so.


I guess the big thing right now is getting some bore measurements to see where your at.

Given the engine only has 55miles on it that will work against you since the original piston rings haven't worn into the cylinder wall yet.

If the engine had 15,000 miles on it.... then I would be a little more optimistic that the bore diameter is not too far off where you need it to be.

I belive the scratches from the honing process are usually about 0.0005" in thickness.... which are removed from the cylinder walls ( piston rings wear the wall and create a polished surface)

If fact you can get away with not honing sometimes if the piston ring material is relatively soft ( unlike chrome rings for example )


Just for the record what kind of rings did you install? ( material composition specificly )

[PrecisionBoost]

Oh hey... I have an idea..... you probably still have your old stock pistons right??

You should measure them to see what diameter they are..... that will give us a pretty decent idea as to where your cylinder bore is at.

I don't imagine that the skirts are scuffed to badly with just 55 miles on the engine.... so the measurement should be pretty decent.

The cast pistons shouldn't have as much taper as the forged ones.... but you would be best off taking measurements at the top of the crown, 3/4 of an inch down from the oil ring and say 1.3" down from the oil ring just to see what they are at.

[greenbluewoo]

heres some pics of my new strut bars front lower strut bar and rear flocking kit will post pics when I do my dash and door cards

[greenbluewoo]

made a little more progress new poly bushes fitted on the rear rear strut bar how the car looked rear beam on with rims and rear bumper engine bay painted still needs clear and need to paint the bottom part z20let lighted flywheel 2.0 conversion mount and power steering mount from gse turbo commets welcomed

[buddha102]

can u answer my pm? I asked u where did u get that manifold for the turbo?

[greenbluewoo]

pm sent

[Big Jeff]

were those strut form a
MK2 astra

[greenbluewoo]

lanos struts astra mk2 springs