Building a B21FT from the ground up

All the pictures in this thread have disappeared, but I've re-hosted most of them here:
http://www.cravingboost.com/cars/B21ft-rebuild-2004/

Hey all, we're finally building up a "proper" motor for my brothers 1983 242t. My goal for this thread is to have you guys help me decide what parts to use and what machining needs to be done. Help me learn about all the "squish vs swirl" tactics and stuff like that.



Intended use:
This is for my 18yr old brother. He's building this engine as credit for his Senior Project in high school, and because he needs his car back! It will be driven hard, raced, railed, flogged, etc. It'll get good oil with frequent changes and will be maintained regularly, so it's not going to be abused.

We need a reliable engine that'll last him 10's of thousands of miles without much hassle. I mean if he lets it knock for 6 months straight and turns up the wick to 30psi, of course he'll have problems . He knows this.

We want a high compression motor with great off boost power (like mine) and killer boost power. Very driveable, both daily driving and racing. We're not looking for "boost number braggin' rights" as StealthFTI said, but we're definately looking for the most usable power. If it makes insane power at 10psi, GREAT! Gives it a slight sleeper aspect, "Yeah I'm just running 10psi........ ".

Budget:
I'm thinking like $500-1000 US. Our dad is backing the buildup, and he says we should do what needs to be done, without going completely wild. I agree.

Current parts on the car:
The current shortblock is some POS B23 that we tossed in. That was a stupid idea, cause it sucks balls. I think it's spun a rod bearing, so he's just not driving it. It's time to do this right.

It's got a 398 head that I lightly rebuilt. I dissasembled it and beadblasted everything. Lapped the valves and replaced one loose guide with a new one. New intake valve seals. New lifter bucket absorbers. B cam (though it could easily be an A-cam or a K-cam if that will make the engine even meaner). It appears that the head was surfaced shortly before we got our hands on it. It came off my parts car which threw a rod (supposedly, I haven't checked yet). When I took off the head the Elring headgasket looked BRAND NEW. Newer than a one month old HG that I've removed before. It also appeared to have new absorbers and new intake seals. Lets just say I was happy to find it in such good condition!

Megasquirt is already installed and works great. We've got regular turbo injectors on and.... jeeze I forget what FPR. It might actually be a 2.5bar one. Soon enough we'll toss on some brown tops or probably CFI injectors.

Ignition is still just the K-jet ignition. One day we will upgrade to MSnS, but it might not happen before this motor is done. Then again, if you guys talk me into it, it will happen before this motor is done. It's got crappy spark plug wires and a stock coil. (maybe I'll just finally put EDIS on my car and he can have all my MSnS stuff including my MSD wires.)

It has a 60/63 turbo, pretty tight shaft.

Stock 242 downpipe (with the stupid cat), then 3" exhaust straight back with what we think is a flowmaster muffler. We got the whole system from a buddy for a great price, it's not perfect but it works for now. Once the car works again we'll install a 3" downpipe and cat.

It's got an M46 transmission, 8.5" flywheel and pressure plate, NEW clutchnet.com 6 puck sprung hub clutch.

I forget what else we're using that's relevent, please ask if you have any questions.

Parts we have and are going to use for the new shortblock:
B21FT block, about 190,000 miles. A tiny little lip at the top of the cylinders (very vauge I know, but my parts car with the same mileage had a HUGE lip compared to this)

Ohh yeah, and this is important. This B21FT suffered from a spun rod bearing about 6 months ago. The crank is chewed up a little bit, and I'm hoping that 1st or 2nd undersized rod bearings will clean it up. If not we'll find a new crank. I'm sure the main bearings surfaces will be turned too.

M-rods. The one that spun and got chewed up will be replaced. I've got 5 good rods to choose from, and can easily scrounge up many more if needed.

Pistons are 1st OS B21F Kolbenschmidt, slightly used. I just got them from Matt Dupuis. They're lightly scuffed up on the sides, I'll post up pics if you want to see. Also they're flat top pistons, and in their designated motor are supposed to yeild about 9.3:1 compression.

Just for fun I tried to slide one of these pistons into a cylinder, and it definately wouldn't fit.

New parts for the buildup:
New oil pump, recommendations?

New water pump, belts, all gaskets, etc. New rear main seal, front crank seal, basically everything.

Humm, we should get a new crankcase box too eh?

Main and rod bearings, undersized depending on what the machine shop says about our crank.

Piston rings

Timing belt pulley, it's already got a brand new timing belt.

Electric fan (still gotta find one of those)

Machining to be done:
Turn the crank

Overbore the cylinders to match these 1st overbore pistons

O-ring

Possibly deck the block to ensure a flat surface and enhance squish (please elaborate on this for me guys)
__________

I think that should do it. I'd like you guys to help me with suggestions on stuff like deciding how much to deck the block, what squish to look for, static compression ratio and dynamic compression ratio, etc etc.

Stealth, I'd love to get this worked out before you leave on the 10th of Oct. My brother and I will probably have started this buildup by then. It would be wonderful to have a good idea of the details before I get too involved. Thank you for making me realize that I needed to come out with a plan of attack, just typing this out has helped me already.

Thanks guys!

John

some preliminaries

John,

a good start for a plan.

the budget is doable...but tighter than I usually work under. For reference purposes only, my MS bill is usually $800+ on just the shortblock.

to do what you seek, within the budget, will require some ingenuity and prioritizing.

first things first: do you have the green manual TP30170/2 Engine reconditioning?
....$19.35 plus tax and ship from volvotechinfo.com [the last time I ordered a manual from them, it came in 7 days.]

....or you might get it from one of the ebay guys [skip's?...or]

you need the book, it will give you and your machinist the correct specs that you are gonna need to do this.

from what you say, I am understanding that your brother is doing the machining [or as much as possible depending on equipment available]. that will conserve some $$.

there is one set of specs that the green manual does not supply for the machinist: the diameter of the main journals and rod journals....the outside of the bearing shell dimensions for proper sizing of the rods for proper bearing shell crush; and the outside bearing shell dimensions for the main journals in the block so the main bearing shells are properly crushed and retained.

the only aftermarket supplier that I know of that offers those dimensions for their bearings is Fed-Mogul. Check that out and track it down. You have to have that for proper bearing fit; especially if your brother intends to have the motor live. I use F-Ms because of that little detail.

in the next few days, I will put together some info and recommendations for you guys on what to do to the SB; and how to get to tight squish.

I am going to presume a block, crank, rods, intermediate shaft hot tank and magnaflux...right? you mag the block; esp the main brg webs; and esp #1.

the crank get tanked and magged; and checked for true

the rods get tanked and magged; checked for straight; resized and rebushed.....full floaters are stock; so plan on new rod bushings....you get to size them right...

you will balance the crank neutral; and the rod/piston assys to the same weight.

more on the block etc later...we be just starting.

Thomas Fritz
...the stealth FTi

One more thing, Erik's engine will be tuned (very well) with my wideband O2 once we get it running. We might even toss a knock sensor into the equasion, because Megasquirt is now capable of retarding timing at every knock event.

stealthfti said:

first things first: do you have the green manual TP30170/2 Engine reconditioning?
....$19.35 plus tax and ship from volvotechinfo.com [the last time I ordered a manual from them, it came in 7 days.]

Click to expand...

No I do not have that book. I'll see if Kenny (captain bondo) has one I can borrow, because he's local to me and I finally met him. If not we'll just buy one. Thanks for that tip, I was wondering how the machine shop would know the specs.

stealthfti said:

from what you say, I am understanding that your brother is doing the machining [or as much as possible depending on equipment available]. that will conserve some $$.

Click to expand...

No, sorry if I mislead you. We will find a machine shop that we like, and he will be doing all the fancy work. We'll most likely stand over his shoulder and help out though, because remember my brother is making this into a huge school project, and needs to document every step along the way. But aside from the hardcore fancy expensive machining tricks, we will be doing everything else together. Don't want to pay a machine shop for something we can figure out.

Also you mentioned resizing the rods. I was at a good machine shop the other day and they explained this to me, and actually showed me the tools and how they're used. My question is, when the rods are resized, wouldn't you need bearings with a larger outside diameter? Or are they not altered thaaaaat much? Do the main bearings and caps also get this treatment?

stealthfti said:

I am going to presume a block, crank, rods, intermediate shaft hot tank and magnaflux...right? you mag the block; esp the main brg webs; and esp #1.
The crank get tanked and magged; and checked for true.
The rods get tanked and magged; checked for straight; resized and rebushed.....full floaters are stock; so plan on new rod bushings....you get to size them right...

Click to expand...

Thanks, I didn't know that the crank/rods/I-shaft needed to be hot tanked also. We will get all these parts tanked. Others have said that magnafluxing is about $65, that should be do-able too. I guess we wouldn't want to build a nearly perfect enigine, but later find out the hard way that one of the rods was cracked internally.....

stealthfti said:

you will balance the crank neutral; and the rod/piston assys to the same weight.

Click to expand...

Lucky for me I've got a good buddy who does engine balancing, and I'm sure I can get this done for free. Thanks for mentioning it though, I might not have considered it otherwise. Do all the rotating parts get balanced after the maching work? Also, would he want to balance the assembly with the flywheel and crank pully too????

Thanks! This is getting me all excited. I just wish I had this kind of time and money to spend into a rebuild of my motor! Sometimes I feel like it's a ticking timebomb.... .

John

John,

re the rod resizing: the bolts are pressed out; the mating surfaces of the rod and the cap are both dusted off a few thou, and the bolts reinstalled. That makes for a smaller diameter non circle. Then, when honed out back to correct circle size, it is all round, and holds the bearing shells all the way around.

the main caps get dusted off a few thou, but the block itself is not machined in there. when the main caps are installed, it is again a smaller diameter, non circle. the align honing restores the perfect circle.

when the rods are resized, the center to center length is shortened a couple of thou. when the main bearings are align honed, the effect is that the crank is actually "raised" in the block a couple of thou.
this shortening of the rod C-C length and the raising of the crank in the block are two things that would need to be done BEFORE machining the block deck for piston deck height. which is part of what I was referring to that things are done in sequence.

when the rods are resized, they are usually also rebushed. the new bushing for the wrist pin has to be honed for correct pin clearance. [The volvo redblocks all use full float pistons: the rods are bushed.] And it is at that point that the very slight differences in rod C-C length from the resizing can be accounted for and compensated for...by offset honing of the wrist pin bushings. That way the rod C-C lengths can be restored to exact same for all four rods.

for a motor that you intend to 'drive aggressively' from time to time, you have to make sure the rods are right. that is why you tank and mag them and verify straight....and resize and rebush. This is not an area to shortcut.

new rod bolts/nuts are your call. the volvo rod bolts are good. for a race motor, I would definitely replace the rod bolts. For street: the decision is yours; your machinist can tell if they are weak....he will know when he torques then down during the rod work. If he says to replace, replace.

back to the block:
...once tanked and magged to verify no cracks in the main bearing webbing or cylinder walls or head bolt holes,
...the main bearing journals are checked for round; they are checked for diameter; and they are checked for alignment. It does become a bit of a judgement call on whether or not to align hone [aka align bore] the main bearing journals. To me, if they are not all four perfect in round, diameter, or alignment, the block gets align honed. This is not an option in my book, even for a "street" motor. But that is also your call; but listen to your machinist's judgement/recommendation.

I prefer to have the mains align honed. It restores and establishes the centerline of the crankshaft; and therefore the center of the block: the center of the universe of the rotating assembly...which is pretty d##n important to me.

...once the main bearing journals are checked out and the work performed, the attention turns to the cylinder bores:

...you are going 1st OS; that is just about precisely 0.020in. Which means that the cylinders can be "bored" with a boring bar or boring machine. The other method of increasing the bore size is by "honing". Both methods accomplish the goal of getting to the 0.020in OS; but the actual boring with a boring bar/machine is more accurate for this reason:
...the boring bar will bore out the cylinder truly perpendicular to the crank centerline...we are keeping the faith by being true to the center of the universe. Honing the cylinders out to OS is fine; but that only follows the bores as they are. If there has been some slight core shift, honing does not correct that. Boring does not 'follow' the cylinder as it is; the boring bar is set up to do it perpendicular to the crank. Remember: the crankshaft centerline is our center of the universe. And we want to have things that are supposed to be perpendicular to the crank, to BE perpendicular to the crank....AND we want things that are supposed to be parallel to the crank to actually BE parallel to the crank.
...boring to 1st OS will be done in basically two stages: the boring bar to take the diameter out to about 0.017in OS, then honed that last 2 plus thou. That gets the wall finish correct with the right cross hatch. A final hone with a flex hone [the balls on wires thingy] will give a nice "plateau surface".

piston to cylinder wall clearances is an area rife with opinion. For your purposes, and using used pistons, I would go for wall clearances of right at 0.002in....max. 0.0015in would be nice; but i won't insist. Check the green book specs; you will see that I am on the loose side....heehee. [an inside joke]

let's talk crankshaft:
...that crank with the spun rod bearing needs to examined closely. If it passes visual and mag test, and is straight, then ok. Personally, if the spun journal shows ANY discoloration from heat, I would get another crank; and put that one on the shelf for a DD NA motor.
...when grinding to undersize bearings; or just polishing the journals....go for main and rod bearing clearances of about 0.0015in to 0.0018in...that is middle of specs.
...keep the thrust clearances within the specs there at #5 main. Your machinst can and will check that.

which reminds me: you should make a copy of the green manual and put it in a binder to "loan" to your machinist. put the pages in protective covers so they don't get greasy fingerprints on them. Your machinist will believe the clearances when he reads them in the book....and he will have the right clearances info to work from.



how to get to tight squish........

....I will go over in the next post.

TF

great thread! i'm glad you are sharing this info with the board and not just through im/pm/email. i was considering a b21 build up, and your setup sounds perfect to me. good off boost, and good top end with boost.

sweet stuff

Brilliant post ...
Now for the tedious task of translating allt that techical mumbo jumbo to Icelandic for my machinist to understand

~Arnar

sweet stuff

Brilliant post ...
Now for the tedious task of translating allt that techical mumbo jumbo to Icelandic for my machinist to understand

~Arnar

Once again Stealth, I am forever in debt to you. This is helping me out so much. With a lot of the things you're talking about I've heard them mentioned here and there, and seen some tools in a few machine shop, but your explinations really clarify everything for me.

Also, I talked to my buddy the engine balancer, and he said that we'll get that done up no problem. He told me to get all the machining work done first, then bring in the crank, rods, pistons, wrist pins, flywheel, and possibly the pressure plate and crank pulley just for overkill. He was mentioning that if a crank is just a few grams off balance in a certain direction, that equates to 45 LBS of force at 3000rpm, or something to that extent. So it's imperitive to completely balance a "built" motor if you expect it to last for a long time.

Thanks for the clarification on rod resizing, that makes perfect sense now. As I said I've got 5 good rods, so I'll take them all in and my MS will choose the best ones. And I can easily get more if needed, say if one or two have internal cracks or something.

Here is the only picture I have of the spun bearing. It's pretty nasty but I hope it's not garbage. But if it is, I need to know so that we can be on the lookout for another crank pronto. The second layer there, I'm not sure if we're looking at bearing or crank surface.... might actually be bearing.
http://www.vipinfoservices.com/john/images/erik-engineB21ft.jpg

John

John,
that is a very nice picture....of a very UGLY result. ouch.

That crank might clean up at ten thou under; but I doubt it. Probably at twenty thou under. Personally, I would find another crank to start with: any B21F from '78 to '82 will be forged crank and M rods. That, I know for sure. Earlier than 79 is probably forged; but it has been so long since I tore one of those down that I forget.

The reason I suggest starting out with a different crank is twofold:
...that journal surface IS chewed; and I cannot determine from the pic any discoloration from heat. But, as bad as that looks, I suspect that there was some heat. Even if it were to pass a magnaflux exam, I would always have that nagging doubt...
...the sides of the rod journal look a bit ragged. That bothers me because the rod axial play is controlled by the clearances on the sides of the journals. Sure, they may be okay; and they may clean up just fine. but...

re balancing: since you have that available, go for it. It may not be an essential operation for a street motor, but it is a worthy thing to do.

Another option that may not be an essential for a street motor, but if available, is worthwhile: using a honing plate [AKA boring plate or torque plate]. A honing plate duplicates the stress on, and deformation of, the cylinder walls by the head bolts. By torqueing down the honing plate for the boring and honing operations of the cylinders, you duplicate the cylinders' walls as they are when the head is installed. When bored and honed with the plate on, you end up with truly round cylinders when the motor is together and running. For a competition motor, use of a honing plate is a very smart thing to do.

re the engine lubrication system:
...you should review the 'oil pump shimming' topic done recently. The later oil pump, PN 1346144, is the higher volume oil pump to use. The Melling M181 oil pump is a replacement pump for that pump; and would serve very well. The oil pump in that B21FT is the older PN, lower volume pump....so definitely upgrade.

...retrofitting oil squirters into the B21FT block [as CNGBrick has done to a 23 block] would be a procedure that would be very worthwhile. But in this instance, for this motor, going that route is beyond the budget. It would be a time consuming custom machining and fitting job. I bring it up for future consideration for a build with both a larger budget and a longer time frame.

One other thing: are you using an old style exhaust manifold? or a 90+ manifold?

***

The subject of squish clearance is tied to a term that need to be defined and understood: deck height.

The proper definition of the term is this:

"deck height"...the distance from the crankshaft centerline to the block deck.

Volvo has never published a specification for "deck height" for the SOHC redblocks.

The "deck height" of the block can be measured: measure from the crank centerline to the top of the block. no biggie. And since there is no published specified dimension, you DO have to measure it....or rather, your MS will have to physically measure it.

In common usage, the term "deck height" is not used precisely correctly. When most people talk about 'deck height' or 'piston deck height', they are using the term to describe the height of the piston crown at TDC. If the piston is sticking up out above the block deck surface at TDC, it is referred to as a 'positive' deck height. If the piston only comes up flush with the block deck at TDC, it is called 'zero deck height'. If the piston stays below the block deck at TDC, it is called 'negative deck height'.

Even though there is not a published "deck height" for the block, we can calculate the approximate dimension. How?

....take half the stroke, add the connecting rod C-C length, add the compression height of the piston....and the total length will be close to what the block is. The compression height of the piston is the distance from the wrist pin centerline to the top of the piston: the crown.

example:

B21 stroke...............80mm............3.1496in

half stroke is.............40mm............1.5748in
rod C-C...................145mm...........5.7086in
comp height..............46.5mm.........1.8307in

approx deck height.....231.5mm.......9.1141in

I said that that would be close to the actual block deck height. Why is it not the actual block deck height? Because Volvo varied the "deck height" in order to vary the compression ratio for different markets. Using the numbers above....which are B21FT numbers....we get pretty close to the actual "deck height" of the block. In actuality, in a B21FT, the piston deck height is negative from the factory about eight to ten thou; and I have seen them as much as negative thirteen thou [or thereabout].

I know that because when I do a teardown, one of the measurements I take and record IS the piston deck height. That data is useful to my MS for when they get ready to determine the amount of material they will have to machine off the block deck when they get to that operation, in order to give me the piston deck height I want at assembly.

***

To get good squish clearance, the piston crown has to come within 0.040in of the cylinder head when the piston is at TDC. A stock Volvo head gasket, or an Elring head gasket, is 0.047in to 0.049in thick when it is compressed between the head and block. [I do things based on the 0.047in value] Therefore, to get to the 40 thou squish clearance, the piston will have to rise up out of the cylinder at TDC a distance of at least seven thou in order to make up for the thickness of the head gasket, and to get to the 40 thou squish clearance when the head is on.

So.....your MS will have to either measure everything and calculate the amount of block deck material that needs to be machined off to end up with a postive piston deck height of seven or more thou....OR they will have to do a dummy assembly of the shortblock and actually measure where the pistons are, and go from there.

This is why you do not surface the block until the main bearing journals are checked, and possibly align honed; until the rods are resized and rebushed; and until the pistons are measured for compression height dimension.

How tight should you go for for a squish clearance? That depends basically on the absolute redline and the piston to cylinder wall clearance [piston rock in the bore]. For your engine, I would suggest a squish clearance of 0.035in to 0.037in. That will put you into tight squish.

For reference, in my pbase galleries, the Sarah Project B230FT is a 37 squish motor; the L Block motor is a 35 squish motor. You can see what 'plus ten' and 'plus twelve' look like.

What you decide to go for, is for you to decide on. Why? Because you need to read up on squish; and because we have not discussed absolute redline.

...and that is a different topic.

Thomas Fritz
...the stealth FTi

Thanks Thomas. Give me a day or two to myself, then we'll discuss the remaining topics. Though if you have time, and want to start listing them, please do. I'll be very busy the next few days and probably won't get much time on T-bricks.

John

i hate to derail the thought process that's going, but i have a few questions. about tighter squish

ok, so if you go super tight squish, the piston would come out of the block at tdc a lot. so couldn't you shave the head a little and shave the block a little less.

how would you figure the max rpm's allowable? would it all be determined by the valve springs? so for a little higher red line, go better valve springs. or would that cause other parts to be the limiting factor?

and if the piston would hit the springs, couldn't you cut valve pockets in the top of the flat top's, so they would look like this, http://www.rosspistons.com/items.php?Custom=N&ItemTypeID=23 ?(just did a google search, this was the first site i found) if cost wasn't an issue, that is. how much extra room (piston to valves) would that give you, and does that mess up swirl?

thanks guys, and i hope you can clear up some of these questions for me.

stealthfti said:

The reason I suggest starting out with a different crank is twofold:
...that journal surface IS chewed; and I cannot determine from the pic any discoloration from heat. But, as bad as that looks, I suspect that there was some heat. Even if it were to pass a magnaflux exam, I would always have that nagging doubt...

Click to expand...

Couldn't agree more. Remember when Matt and I spun bearings within a couple of months of each other? My crank looked like that. We pulled my engine out, flipped the block on its back and took the bearing caps off and then spun the crank. You could see the crank was warped. You didn't need to measure, it was visible. That one went in the back of the truck for the next run to the dump.....

Whay not find a B23 or B230 shortblock? I always assumed people built B21s because it's what they had (and weren't rebuilding) or for racing regs. Why not go with the larger displacement?

I'm following this thread VERY closely and learning LOTS on how to do a reliable yet powerful B21, I'm going to do something similar with my '79 B21 that will be a MS +T motor and learning all the RIGHT things to do helps lots. Once again THANKS for the detailed info on the machinig processes that should be done and more importantly the reasoning behind them. Tim

Mods/Admin - Can we sticky this thread? It would be a nice addition to this forum at the top near RedDragon's stroker B23 thread...

John,

A few more things on the preliminary side:

...the used pistons need to be CLEAN. not for the aesthetics of 'lookin' purty'; but for the purposes of having CLEAN ring grooves. If the pistons are not already clean; the MS can clean them up so that they look like new. And that cleaning will clean the ring grooves without damage. I do not use ring groove scrapers. The potential for damage to the grooves is so great as to be almost a certainty. Damaged ring grooves leads to improper ring positioning and operation: the rings don't seat right; they can't move correctly; they can't do their job...you have a problem. Rings have their needs too. Do your part to ensure the rings' ability to sit in the grooves and move freely and correctly; and THEN they can seal properly.

...the wrist pin bores have to be clean. The pistons are full float; ie, the wrist pins move back and forth inside the piston and con rod bushing, and they rotate as well. The clearances are in the tenths of a thou. If you think you can verify proper clearances in that range on dirty surfaces, you are deluding yourself.

The two main areas of problems that lead to the necessity of replacing the pistons are:
...wear and damage to the ring grooves; by deposit build up over time that becomes an abrasive, improper cleaning, or heat damage to the ring land area
...wear to the wrist pin bores in the piston. Those bores do 'egg'. The piston is aluminum; the wrist pin is GOOD steel....the piston wears first.

Clean pistons are much easier to visually inspect, and much easier to verify proper clearances on. And for balancing purposes, clean pistons can be weighed accurately.

Replacement ring choice is another of the areas that is rife with opinion; which ranges from 'simple' cast iron rings to exotic gapless rings. I leave the exotic stuff to others; because it is a matter of preference. I am not 'dissing' the more exotic ring designs, they have their advantages for their intended uses.

I choose to keep it as simple as possible; and just try to make sure that the simple is done correctly. When re-ringing a volvo, I use Deves Rings. Yes, they are the 'simple' iron rings....and they work well. IF the attention to detail is paid.

***

When the block is hot tanked, the intermediate shaft bearings have to be replaced: they are damaged in the tanking solution. The freeze plugs are normally removed prior to the tanking so that the cooling passages can be thoroughly cleaned, and to let the scale and crud flush out. All oil gallery plugs are also removed so the passages will clean out as well.

Who supplies the freeze plugs and intermediate shaft bearings is for you to work out with your MS. I have my MS install the freeze plugs. I could do it; but I am lazy. I install the oil gallery plugs later...after I brush out and thoroughly wash and flush the block and oil passages. That is definitely MY job; and my responsibility to make sure that those are clean. And it is my job to make sure that there are no restrictions to oil flow through the passages.

Back to wrist pin bushings a minute: if your MS supplies the bushings, that is one thing; because if they end up needing to redo a bushing or two when adjusting the rod C-C, then they can get more bushings. If you are going to supply the wrist pin bushings, then order in eight bushings. That way your MS won't run out of bushings. Save the ones not needed; you can use them on the next motor.

***

I will continue this in a couple of days.

***

re the question on squish and surfacing the head vs the block:
...surfacing the head does nothing to affect squish, since the head surface is still separated from the pistons by the HG. Surfacing the head will just make the combustion chamber smaller, and bring the valve heads closer to the pistons.

...in the SOHC motor, the valves are perpendicular to the piston crown; so eyebrowing the piston crown is not the way to relieve the piston crown for more valve clearance. That would require a saucer like cut. But cutting a relief saucer in to the top of the piston would diminish the purpose of going with flattop pistons: to provide the most compact burn chamber possible for the purpose of achieving fast burn.

I can see the possibility of such valve reliefs in the piston crown on a SOHC piston only if using a camshaft of VERY high lift...in a very tight squish motor. The T cam does not lift the valves above the head deck surface. An A cam will lift the valves 0.020in above the head deck...on an unsurfaced head. The A cam can be borderline interference, depending on amount of head surfacing and amount of piston positive deck height. Going with cams of higher lift than the A cam will make a tight squish motor interference; or at least you should assume that to be the case. Precise measurements and calculations would confirm the situation on a particular motor build.

Absolute redline is a somewhat involved discussion; which I want to wait on. In the meantime:

the factory redline for the SOHC redblock is 6500 RPM....at least that is what is on the factory tachometers. I presume that to be pretty close to the actuality. Can you rev a stocker higher? sure. will it live? yeah....for a while.

Consider this: the stock redline is 6500 RPM: in a motor that has "heavy" pistons; in a motor that uses "weak" valve springs. Those are just two of the factors that affect redline. Would I go with "stronger" valve springs? no. Stronger valve springs have their drawbacks; and for my purposes in a street motor, the drawbacks are not worth the supposed advantages. That is my opinion; others are welcome to theirs, and their choices.

My point here is that there IS more to it than just piston weight and valve spring pressures. And hopefully I can present my viewpoint on that coherently.

***

Dale, I remember.

***

Thomas Fritz
...the stealth FTi

wow lots of info, let me throw some pointless info in:

Heres what I would do:

B21ft, machine as necessary.
Skip oringing, just use a Copper sprayed Elring gasket. Remeber, oringing keeps the head gasket from acting like a FUSE, this means possible boom big way. Plus, you'll save money.
405 head, K cam
60 trim
BT injectors
you do the tuning via ms
T5.

He'll be able to beat that setup till the cows come home, will be pretty damn quick (if you can drive I think a 60trim will net you mid/low 13's on a light enough car) and pretty reliable. Use oem parts for the rebuild (deves rings? I believe thats what I've been using, seem to work well).

Thats it, trust me, that setup will work great.

John,

some more of the preparatory things:

As suggested by Doug, I would forego the O ringing of the block; and put that money into the align honing or other block related items. Your choice of course, but unless you plan on running really high boost regularly, the money can be better spent elsewhere...like new valve springs, or new head bolts.

Some review of others' experiences of boost levels run vs HG problems would be in order; as would comments and suggestions by others on that aspect.

Some things won't be known until your MS tanks and mags things, and checks the dimensions.

I know that I am probably overlooking something, or forgetting something regarding the getting ready for the machine shop, and what we have covered so far. So any suggestions as to what I may have missed thus far is welcome.

One thing we haven't done yet is finalize the squish clearance to go for. Part of that decision is dependent on the RPM redline you choose to use. You will have to advise me of your choice on that.

The use of the motor has been stated; the desired redline is to be chosen....and discussed. There is one more area to bring up before we proceed with some assembly suggestions. That area is "expectations". And that gives me the most pause.

Why? because I do not want to nor do I intend to mislead you or anyone into thinking that by going tight squish you will suddenly have a motor that makes some amazing amount of power just because you tightened up the squish clearance. That isn't what tight squish does.

A very brief summary:

Tight squish is an assistant; it is an enhancer; it is an enabler.

...it assists in speeding up the burn rate by increasing the turbulence in the combustion chamber.
...the faster burn rate of the air fuel mix shortens the burn time; so the air fuel charge finishes burning sooner.
...the shorter burn time reduces the potential for detonation to occur, because the air fuel charge burns up before the pressures can rise enough to create detonation inducing pressure spikes.
...because tight squish does all of the above, it allows you to run higher static compression ratios, and the higher effective compression ratios that boost provides.

It is the higher static and effective compression ratios that makes the increases in power; the tight squish helps you run those higher compression ratios.

Normally, the way boost motors are set up is this [approximately]:

the low pressure turbo approach:
....SCR of 9.5:1 or higher; and low boost of about 7 PSI or less

the middle of the road:
....SCR of ~9:1; moderate boost levels above 7 PSI

the high boost build:
....SCR usually under 8:1; and boost out the wazoo

The reasons for these various combinations is one of octane limitation [AKA detonation resistance]: the higher the effective compression ratio that you want to achieve via the higher boost pressure was limited by the octane of the fuel. If you wanted the good offboost performance that a higher SCR would provide, you ran lower boost. To be able to run the high boost, you had to drop the SCR....or up the fuel octane rating....or both.

Tightening up the squish clearance enables some blurring of the lines; because tight squish reduces detonation potential. It could be said that tight squish is an octane booster.


How does this tie in to your motor?

Going tight squish with flattops is going to give you a static compression ratio definitely above 9:1. How much above would have to calculated out.

The high SCR will improve the offboost performance; and will affect just how much total boost you can run.

How tight to go with the squish clearance is a judgement call. As I already suggested, going for 0.035in to 0.037in will put the motor into tight squish. Originally, the B21FT was nowhere near good squish, much less tight squish. So going for 0.035in to 0.037in will be a great improvement. Coupled with the SCR increase from 7.5:1 to over 9:1, you will definitely see a power increase...even at stock boost levels. [Whether or not that would qualify as "insane power at 10 PSI", I do not know.]

From that point, the redline factors in. Because the redline will affect just how tight you can go squish wise.

****

more later,

Thomas Fritz
...the stealth FTi

Thomas

once again your breadth and depth of knowledge in this subject is astounding! I have wanted to build a motor for a long time. This information makes me rethink what I was going to do and items I had no idea about. Thank you! It would be nice if you were a registered user so it was easier to find all of your incredibly informative posts.

thank you again

John your brother had a great idea to turn a motor build into a project! Best regards to the project and yours.

Nice thread.

Use new rod bolts. Think of them as insurance.

For the naysayers who want to know why he is building a B21, why ask why? It is what it is, and it is a great honors project.
I have 2 going on just like it. Nice students deserve nice projects and the recognition that comes with it.