Forged pistons/ rods and block machining question

[Ian91]

So I'm building a forged 93t for my gsr, I've bought a lot of parts already but there's a few things I'm not sure on, I'm using a Sohc 93 block without oil squirters,

1. Is it better to use the 93t or 93 crank, or do I just choose depending on the wear on the 2? Are there any differences between the 2 from factory?
2. What bearings are people using?
3. I'm yet to buy the pistons and rods and I also still need to have the block machined, do I buy the pistons first and then have the block machined to suit or do I have the block machined then buy pistons to suit? The same questions for bearings
4. 3gste head studs apparently fit, are they a direct fit or need to be cut down or have the block drilled and tapped?
5. Where do I buy the revised lifters for the 93t? Or do 63t lifters fit?
6. If I'm replacing valve springs and stem seals should I replace the valves too? And when I have the head machined should I just have it skimmed or should I have the valve seats done too?
7. Last question, after the block and head has been machined how do I know what my compression ratio is? And what is a good compression ratio for these motors? Should be running 18-20 psi hopefully, and how important is the compression ratio? Can I just have it all machined and then bolt it together with the standard metal head gasket without testing compression ratios or is that gonna give me problems?

This is the first motor I've rebuilt so extensively so I'm a little lost, I have that American book about how to take all the measurements and what to machine and all that but some doesn't make a lot of sense to me -_-

Thanks in advance everyone

 

[khubner1]

1: from what i've heard they're the same so use which ever get you the best tolerances when being checked with flexi guage. factory tolerance is 0.02mm to 0.05 mm so you want it to fall within this limit

2: acl race series seem to be the choice

3: buy pistons/rods and have mechined to suit you don't wana mechine to say 50 thou over and end up with to much slop

4: don't know

5: EBAY and MEEK

6: only if they out side tolerance

7: not sure

 

[BMGTZ]

1. Is it better to use the 93t or 93 crank, or do I just choose depending on the wear on the 2? Are there any differences between the 2 from factory? I would use what came with the block...unless it is proven the turbo crank is better

2. What bearings are people using? I use kings as they seem a bit more forgiving that ACL in the unfortunate event of a spun bearing

3. I'm yet to buy the pistons and rods and I also still need to have the block machined, do I buy the pistons first and then have the block machined to suit or do I have the block machined then buy pistons to suit? The same questions for bearings

the block and crank should be checked for wear as the first port of call. From that wear check you will be advised of the correct size for both the pistons and the bearings.

4. 3gste head studs apparently fit, are they a direct fit or need to be cut down or have the block drilled and tapped? they are a tad long but no need to trim them or to drill and tap anything

5. Where do I buy the revised lifters for the 93t? Or do 63t lifters fit?
Meek or ebay...ebay are the cheapest and probably the same anyway

6. If I'm replacing valve springs and stem seals should I replace the valves too? And when I have the head machined should I just have it skimmed or should I have the valve seats done too?

take the head to a specialist shop and ask for a head service...you will be advised what is "required" in other words if it need new guides...valves...seats

7. Last question, after the block and head has been machined how do I know what my compression ratio is? And what is a good compression ratio for these motors? Should be running 18-20 psi hopefully, and how important is the compression ratio? Can I just have it all machined and then bolt it together with the standard metal head gasket without testing compression ratios or is that gonna give me problems?

the pistons you get will have the comp ration pre-worked out and it will be on the box. I have used 9.0-1 with out any dramas. it is a bit high but these little motors need all the help they can get to spool up a big turbo. Going lower makes them spongy or doughy down low. You can tune around the high compression with less timing but it is harder to tune a doughy motor to spool fast. I used a std mitsubishi head mls gasket and run 18 psi into the daughters engine. it is now running out of injectors tho so need bigger than the 560 evo injectors. i have also installed arp main studs.

 

[Ian91]

thanks for the help guys, ok so once i get the block ready to be inspected them i can measure it all up and see what it can be machined to the buy the piston/rods and bearings then have it machined to suit said parts, ill be using 560's so hopefully that wont be a problem, were the main studs for the 93 or from something else? are they necesary ?

cheers

 

[BMGTZ]

thanks for the help guys, ok so once i get the block ready to be inspected them i can measure it all up and see what it can be machined to the buy the piston/rods and bearings then have it machined to suit said parts, ill be using 560's so hopefully that wont be a problem, were the main studs for the 93 or from something else? are they necesary ?

cheers

main studs are from the 4G63..evo..I used them for added security but they add to cost.

 

[bazeng]

1. . Is it better to use the 93t or 93 crank, or do I just choose depending on the wear on the 2? Are there any differences between the 2 from factory? I'd assume with both being Mitsubishi. They should almost be the same item. The non turbo cranks have been proven with the 4g64 guys. Just get the crank crack tested etc by a machine shop to be safe.
   
   2. What bearings are people using? I use ACL Race / ACL Duraglides.
   
   3. I'm yet to buy the pistons and rods and I also still need to have the block machined, do I buy the pistons first and then have the block machined to suit or do I have the block machined then buy pistons to suit? The same questions for bearings
   
   As Brian has advised. Check what your block allows for. No point buying standard bore sized pistons if your block requires a minimum of 20thou bore/hone to provide a sufficient bore shape. Bearings depend on your crank condition. If you go undersized / oversized. The machine shop should be able to measure and order your required bearings. Also specify your bearing clearances. Some guys like a loose motor (2thou ish), some guys like a tight motor (1thou ish). It is up to you. This will be dictated by the oil you use also so if you want to run a think oil, run tighter tolerances in the bearings and if you like the thicker stuff, you could run looser. Both have pros and cons.
   
   4. 3gste head studs apparently fit, are they a direct fit or need to be cut down or have the block drilled and tapped? No comment.
   
   5. Where do I buy the revised lifters for the 93t? Or do 63t lifters fit?
   Your local car parts shop should also have access to them.
   
   6. If I'm replacing valve springs and stem seals should I replace the valves too? And when I have the head machined should I just have it skimmed or should I have the valve seats done too?
   
   As Brian state. Just keep in mind to, do it once, do it right. Saving on something may bite you in the future.
   
   7. Last question, after the block and head has been machined how do I know what my compression ratio is? And what is a good compression ratio for these motors? Should be running 18-20 psi hopefully, and how important is the compression ratio? Can I just have it all machined and then bolt it together with the standard metal head gasket without testing compression ratios or is that gonna give me problems?
   
   What fuel do you plan on running? If 98ron standard pump fuel, go for something around the 8.0-9.0. The higher the CR, the more responsive but less boost tollerance which would probably give you less overall hp up top. Lower CR will give you more HP up top due to the ability to run more boost but less responsive down low. If race fuel (E85 - C16 etc), go higher comp. Something like 9.0 - 10.0.

 

[4piknup]

http://www.ebay.com.au/itm/ENGINE-BLUEPRINTING-BOOK-STEP-STEP-GUIDE-ANY-ENGINE-308-327-350-289-302-351-/180949808777?pt=AU_Car_Parts_Accessories&hash=item2a2172f689#ht_2339wt_689

Buy this book, it's for v8 mostly but engines are engines.
It will show you all you need and more. Degreeing cams, valve to piston calcs, bore sizing for pistons, block deburring, etc etc.
Heaps of stuff you can do before your engine builder gets your engine.

Buy the book...

 

[Ian91]

I'll look into the main studs,

Baz thanks for the input, I'll take everyone's advice when it comes time

Haha jack that's the book you already told me to buy and it's the one I was talking about, I've read the whole thing twice and some parts I'm unsure on as it's the 1st time I've done this and some of the methods and terms and stuff I don't quite understand, I'll read through it again and post up what I'm unsure of I'll also read through the book as i go through the steps and then I won't forget what's next lol

Thanks again fellas

 

[4piknup]

mate i have read it a dozen times and still pick up bits all the time.
even if you only do the stuff you understand you will be along way ahead of alot of the crowd. and you will know what the builder is talking about and you should be informed enough to not pick a dodgy operator


there is a section that talks about piston sizing. it says that the builder will need (dunno 4thou?) to bore and hone to the next size. (i will talk in inches so that you cant take the figures literally and you will need to talk to your builder to confirm what is said)
so, you need to buy the right size pistons, standard is 4" piston available in 40 and 60 thou oversize (with 1.5thou piston/bore clearance). what one do you want??? easy,
make a piece of fencing wire cut it with your pliers and round the ends. file/grinder it down to a length of 4.037 (40+1.5-4thou)vernier will be close enough. make another wire at 4.057" now poke the shorter wire in the bores and wave it around, if at no point you can get the wire horizontal then you could choose the 040 pistons. if the bore is bigger than the wire at any point there isnt enough meat left in the bore for those pistons, and you need to test with the longer wire.

make sure you get the right pin sizes as there is 21mm and 22mm small end pins

 

[4piknup]

compression ratio is also covered in the book, you need to divide the volume left above the piston when it is at tdc, by the volume above the piston when piston is at bdc.
this means you need to calculate the piston dish volume, down the bore piston height at tdc, headgasket volume, chamber volume... umm.
you need to be a bit careful as a 9:1 pistos could end up at 10:1 easily if you shave the head, deck the block and choose a thin gasket...

oh, congrats on the book purchase, that vizard guy is a guru...my copy is so dogeared now.

 

[Ian91]

Hey jack, thanks for the tips, will defiantly be reading through it a few more times and have it handy while I'm measureing everything up etc. The pistons I want are a 82mm diameter and standard bore is 81mm so I will have to be carefully as to how much can be removed during honing, I can get oversized so I'll just measure 1 million times before I go ahead and buy anything, also it's a piston/ rod combo so the small end size shouldn't matter???

Thanks again

 

[4piknup]

There is a worksheet in the back of the book for measurements and records.

Also, there is cheap micrometer sets available (eBay) they will do you for a while if you are gentle with them. If you think you need them.

 

[caged]

dont bother with main studs, the 93 has a big solid crank girdle anyway. Just get engine builder to measure bore size and order over sized pistons to suit (he will then bore it to the piston size plus P to B clearance). Just use evo lifters, dont touch valves unless engine builder says to. king or acl for bearings, dont bother with race series if daily unless planning big hp. Just get evo 1-3 Arp head studs and get the engine builder to drill and tap the block to suit (is cheaper than 3sgte studs and alot stronger). Go 8:1-8.5 if just running pump and want good numbers. Dont bother measure comp ratio it wont be out by much and wont make any difference to you.
I would invest in a set of high lift cams because they do love good cams up top.
Its just a dirty 4g93 so run big boost and have fun.

 

[Ian91]

There is a worksheet in the back of the book for measurements and records.

Also, there is cheap micrometer sets available (eBay) they will do you for a while if you are gentle with them. If you think you need them.

I saw that, will put it to use, thanks

Yea I already bought some micro meters and the T shaped ones for measuring the bore and stuff

 

[Ian91]

Thanks for the input mate, much appreciated I've looked up both mead studs and are much the same price? And the builder would only charge me more to drill an tap the holes, why are they stronger? Just due to size?

I will be running 264 cams, will these do the job?

 

[4piknup]

i just used the 3sgte studs as suggested by brian.
if the evo ones are fatter then they are stronger... if you use the evo ones make sure there is room for the oil to go into the head as it feeds up through one of the corner head bolt holes. i know it is a issue when using a evo head on a 6 bolt block or if drilling and tapping a evo block to accept vr4 bolts.

 

[BMGTZ]

there is little point in going to a larger diameter head stud unless you intend to run a turbo big enough to have trouble with lifting the head.

on the other hand..just as the 3sgte head studs are an upgrade over the stock licorice head bolts. SO are the mains studs for the same reason. they will screw straight in with no mods except putting a dent to clear the rear of the sump and are less prone to stretch in high rev applications. As has been stated the rod ratio isnt ideal in the 93 which in my opinion makes them all the more worth while given the harmonics amplification that running more boost will bring.

The only down side is the extra cost of the studs and the recommended align bore. However while you could get away without an align bore if you use the stock bolts an the align bore is something I always do when doing a stock OR performance build.