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Old 12-03-2017, 01:04 AM   #1
smncutler
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Default How high a SCR for N/A B23 with VX, pump gas?

Hey all, I'm building the block of my 83 B23F. It already has a rebuilt stock 398 head with VX cam advanced 2.5 degrees. With this and an M46 my 245 is fun, so much fun that I trashed my piston rings five months post head build. I'm aiming to get a little more power from the engine in a minimally invasive way. Porting is too much $$ for me right now - I want to know how much I can skim off the head and/or block without affecting cam timing or causing detonation. No tight squish here. I also intend for the engine to last a few hundred thousand miles while being driven fairly hard and passing emissions on 89/91. I know these engines get their reputation for durability because they're understressed from the factory, I want to know how much I can push it without significantly sacrificing this. Injection and ignition will remain stock, and m46 untouched with 415k.
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Old 12-03-2017, 07:54 PM   #2
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Is it +2.5° because you have an IPD cam gear? If that's the case, I measured that the +2.5 position is actually +4, the +5 was actually +8, and the -5 was -10.

Any amount you cut the head will affect cam timing, about 1° retard for every 0.010" you cut it. I have 0.040" cut off a 530 head and I run Shell 87 with an A cam at -4 degrees and have no detonation problems. That said, retarding cam timing should reduce knock sensitivity because it delays intake valve closing and creates less cylinder pressure. But not much.

If you can swing a Cometic 0.036" head gasket, I'd do that and cut 0.030" off the head and run it. Otherwise, run a stock gasket and cut 0.040". The first option is the better one though.
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Old 12-03-2017, 09:09 PM   #3
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Please note that the 83 B23F is already a high compression motor at 10.5:1.

I have one as well that I run an H cam on. I have previously rebuilt the head with a skim cut for cleanup. A stock thickness HG (running head studs just because) yields a motor that (just barely) doesn't ping on 91 octane at 2ish degrees advanced. I use a Nuke adjustable cam gear. I played with it till it didn't ping any more. Since the H cams are ground 2 deg advanced (generally) and I've cut the head, my guestimation is that its operating at about 3-4 degrees total advance.
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Old 12-03-2017, 09:25 PM   #4
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Find an online dynamic compression calculator......until the intake valve closes, you don't build any compression. Don't get hung up on SCR calcs. Do whatever you can to improve "tight quench". The aluminum cylinder head helps your cause. If it's still up online, look up StealthFTI's thoughts on "tight squish" as he likes to call it. Good luck!
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Old 12-03-2017, 11:09 PM   #5
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Yes, you want tight squish, good quench. Deck the block, not the head.

Also, unless you're altering spark timing, as the the entire curve, you're not taking full advantage of increased compression, cam lift, or anything.
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Old 12-04-2017, 03:28 AM   #6
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Thanks everyone. I have the iPd cam gear, 2.5 degrees nominal/advertised, and a skimmed head. I guess I do want tight squish, don't I need to do a calculation though?
Does a cammed B23F tend to run on the edge of pinging? Considering H and VX cam specs, am I likely closer or further to pinging than Quillc?
Is there any way I can hijack the stock Chrysler ignition?
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Old 12-04-2017, 03:59 AM   #7
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H is a much more suitable cam than the VX, which I don't like.

As for power curve, leave a stock cam timed straight up. You will lose torque along the entire rev band with the timing messed with.
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Old 12-04-2017, 09:51 AM   #8
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Building in some 'tight squish' is the key to running higher CR without ping. You can deck the block, or you can run a thin Cometic MLS headgasket.

I have a B23F with flattops. I added a K-cam, dropped in a 0.027" MLS gasket for ~10.7:1 SCR. The overlap of the K keeps things reasonable in operation. The Chrysler ignition system single-mindedly tries to keep things on the edge of knock, advancing aggressively and making the most of things. Oh, and I added a turbo and 10PSI of boost too, and it all still works great.

Definitely read up on StealthFti's posts about squish. If you can bring the piston to head clearance down around the 0.030" range, you'll see some tangible benefits. Based on how hard my B23 pulls before it builds boost, this should give you the extra edge you're looking for.
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Old 12-04-2017, 05:55 PM   #9
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Quote:
Please note that the 83 B23F is already a high compression motor at 10.5:1.
Not to be difficult or confrontational, but did you actually measure this? The 230F is rated at 9.8 but I measured several out at 9.15(ish). The 230FT I did was a little closer at like 8.4 vs. advertised 8.7.
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Old 12-05-2017, 01:40 AM   #10
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I went for the VX cam because iPd told me it was the most aggressive non-interference cam available for this engine.
Will read up on tight squish.
Any material removed hereafter will come off the block.
The Chrysler ignition is apparently pretty damn good for stock?
Harlard are you suggesting I swap my stock cam gear back on? Anyone want to weigh in on VX cam timing?
Shoestring how much difference will .030 and a cometic make vs stock gasket and .040? By my butt dyno?
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Old 12-05-2017, 02:08 AM   #11
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Quote:
Originally Posted by smncutler View Post
I went for the VX cam because iPd told me it was the most aggressive non-interference cam available to them,.that they have heard of but they have always been complete limp-wristed, girly men so what the fawk do those twerps know? for this engine.
Will read up on tight squish. Don't you will die from the sheer amount of bullsh!t spread here, blindf leading the blind, children imitating some fawked up Father figure..Its simpler than the kiddies want to belive..
Pistons flush with deck
Pistons 030 to 040 OR .120 from the heads quench pads..
B23 pistons are approx 028 below deck..
BEST solution is pistons..deck strength in block and head remains..
BEST by far...

Any material removed hereafter will come off the block.
The Chrysler ignition is apparently pretty damn good for stock? Good for driving saints insane.
Harlard are you suggesting I swap my stock cam gear back on? Anyone want to weigh in on VX cam timing? VX is some limp dick lazy ass nothing cam
Shoestring how much difference will .030 and a cometic make vs stock gasket and .040? By my butt dyno? Zero
Oh dear this again..

Volvos are virtually impossible to ram valves into pistons in most normal sloppy fawk ups...And all that happens if you manage to be so sloppy as to fawk up royally--it can be done--the valve get slammed shut. Do not worry about interference.. Measure things..depth of chamber, + gasket and degrees of crank rotation relative to cam relative to valve lift and learn about cam events and where the valves are relative to piston position.. And if you learn that, then you will be able to use the blathering "dire warnings about interference" as a marker of who is talking bullsh!t and who isn't..
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Old 12-05-2017, 08:54 AM   #12
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John V is correct in saying that you will notice zero difference in head gasket setups as far as power goes, but what the thinner one does for you is to bring the piston and head closer together, in that 0.030 to 0.040 range he speaks of. If I were doing it, I'd take it apart, measure how far in the hole the piston is, and then get a head gasket that puts you there. I suggested the 0.036" in my first post because most people don't want to spend the time to wait for the right thing and that one is about 0.011" thinner than stock.

I would disagree with John V that the VX is "some limp dick lazy ass cam" if you're comparing it to an M or L or the like. You could lay a turd in the head and it would out perform one of those.
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Old 12-05-2017, 12:19 PM   #13
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Quote:
Originally Posted by shoestring View Post
John V is correct in saying that you will notice zero difference in head gasket setups as far as power goes, but what the thinner one does for you is to bring the piston and head closer together, in that 0.030 to 0.040 range he speaks of. If I were doing it, I'd take it apart, measure how far in the hole the piston is, and then get a head gasket that puts you there. I suggested the 0.036" in my first post because most people don't want to spend the time to wait for the right thing and that one is about 0.011" thinner than stock.

I would disagree with John V that the VX is "some limp dick lazy ass cam" if you're comparing it to an M or L or the like. You could lay a turd in the head and it would out perform one of those.
But I compare ALL the emissions cams, stock cams to cams designed and made that the priority is performance first. Continuing the turd metaphor I say its saying this cam is a horse turd, and that cam is a sheep turd and that one is a dog turd and the other one is a moose turd,---they're ALL turds above all.
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Old 12-05-2017, 01:08 PM   #14
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the vx cam is weak. get a real cam before you go nutsoid with anything else, and see where that gets you.
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Old 12-05-2017, 01:19 PM   #15
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Quote:
Originally Posted by shoestring View Post
Not to be difficult or confrontational, but did you actually measure this? The 230F is rated at 9.8 but I measured several out at 9.15(ish). The 230FT I did was a little closer at like 8.4 vs. advertised 8.7.
The 83 B23F was listed as 10.3 or 10.5 by Volvo, I can't remember which and don't have my Bentley Manual near by. In 84, the compression ratio was lowered. It was a one year only deal.
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Old 12-05-2017, 01:37 PM   #16
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I like my VX cam, dammit! I want zero possibility of interference of any kind. Anyone willing to school me on calculating that is welcome to.
I'm headed to machine shop today, should I tell 'em to take .020 off the block? It would leave the pistons below deck. Still not interference. 0.025 would give me the equivalent of 12.005 cam lift, which is interference.
Something something deck strength? How could taking a few thousandths off sacrifice strength?
I know tight squish gets you moar power, but if I can get the same increase with stock whatever in my quest for 140 crank HP, is there any real difference? How is piston to head clearance so advantageous?
For the reassembly, should I leave my cam gear at 2.5 advertised advance or swap the old one on, timed straight up? I like me some midrange torque.

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Old 12-05-2017, 02:12 PM   #17
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Quote:
Originally Posted by smncutler View Post
I like my VX cam, dammit! I want zero possibility of interference of any kind. Anyone willing to school me on calculating that is welcome to.
I'm headed to machine shop today, should I tell 'em to take .025 off the block? It would leave the pistons approx .003 below deck. Still not interference.
Something something deck strength? How could taking a few thousandths off sacrifice strength?
For the reassembly, should I leave my cam gear at 2.5 advertised advance or swap the old one on, timed straight up? I like me some midrange torque.
You have zero chance..The combustion chamber is more than 12mm deep. The gasket from .85 to 1.2mm deep so the valve has to stick out more than 13+ and it doesn't..

the next thing is when does the cam lift the valves and when are the valves at MAX lift?
Typical boring cams have lifted the valves only maybe a mm off the seat when the piston is at TDC, even real fun cams have the valve off the seat maybe 2 to 3.4mm off the seat at TDC..And full lift of intake valve occurs when the piston is way waaaaaaaaaaaaaaaaaaay down the bore, miles from the head...
I've posted dozens of times cam timing diagrams showing max lift at say 105* of crank rotation or 105* ATDC....piston more than half way down the bore.. Stroke is 80mm so half would be 40mm..
How can a valve which doesn't even go below the height of the head, lifted 12-13mm hit a piston that is 40mm away?

None of this is new, it applies to anything with inline valves....

The problem is the low level of basic understanding of event timing and piston motion...and endless repetition of "old wives tales" by people who never have built performance engines who feel compelled to repeat sh!t so they feel they're in with the in crowd, part of the "group"..
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Old 12-05-2017, 02:22 PM   #18
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replacement heads are a dime a dozen still. don't worry about interference... or don't worry about performance.
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Old 12-05-2017, 02:26 PM   #19
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replacement heads are a dime a dozen still. don't worry about interference... or don't worry about performance.
This. And adjust and replace your timing belt on the regular.
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Old 12-05-2017, 02:29 PM   #20
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If the valve has the potential to occupy the same space as the piston I'm worried. If it's half a millimeter outside that I'm good. Just because.

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Old 12-05-2017, 02:37 PM   #21
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then don't worry about going fast. if you keep up with things, it's a minor to non-existant issue. Of all the problems I've had over the years, accidentially winging valves into pistons has been remarkably rare, but the one time I did do it, was with an ipd turbo cam-which is not exactly an extremely high performance or lift cam in the 8v world.
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Old 12-05-2017, 02:39 PM   #22
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get a good belt, don't run a cheap tensioner, you'll be fine.
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Old 12-05-2017, 02:48 PM   #23
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Quote:
Originally Posted by 2manyturbos View Post
The 83 B23F was listed as 10.3 or 10.5 by Volvo, I can't remember which and don't have my Bentley Manual near by. In 84, the compression ratio was lowered. It was a one year only deal.
While I concede that you know all, I personally am confused..I have right here in my little hands the 1990 edition of KS Master Piston catalog and it lists everything imaginable for the pistons they make>>

On page 617 it says:
Motor B23A, 2316ccm
77kW (104,5 PS) 10,3:1
mit vergaser
Fahrzeug 244,
Oktober 1981-Mai 85

Data shows cylinder bore 96mm.......46,4 Comp hgt -3,1 x bowl, 24 x 72 pin 1,75 top ring; 2mmm second ring and 4mm oil ring

on page 618 it says:
Motor B23 A, 2316ccm 82,5/84kW (112/114 PS)
10,3:1; mit vergaser
Fahrzeug 240, 244, 245,760
Oktober 1981-mai 84

Motor B23E, 2315ccm
95-103 kW (129-140 PS)
10/10,3:1 K-Jetronic Einspritzung
Fahrzug 240, 244, 740
August 1979-Mai 84

the data says 96mm cylinder diameter 46,4 compression height Flat top 26 x 72 pin

Block 3 on page 618 shows USA-ausführung
Motor B23F 2316ccm
90kW )122,5 PS= 9,5:1;
K-Jetronic Einspritzung
Fahrzug 240 GLE, 760 GLE,
bis Mai 1984

Data shows 96mm cylinder bore 46,4 and -2,1 deep, rings and pin as before

Now I've only been here what 11 or so years, and yes I have read about 7390 times about 10,5 B23s so it must be right what I read here...

So if TB is, as always, right the question becomes how did the alternate OEM supplier
get stuff so wrong?

It might be a good idea if TB collectively drafted a letter to
Kolbenschmidt AG
Postfach 13
D-7107 Neckarsulm
or called + 0 7132/33-0

And straightened those dumb Krauts out.

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Old 12-05-2017, 03:28 PM   #24
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I can't help what Volvo published. I never verified the numbers, just repeated them.

Compression ratio:

B21FT 7.5:1
B23F Manual transmission 1984 9.5:1
All others, 10.3:1.

You will find the same information published in the Bentley Manual and Haynes Manual. It isn't just folk lore passed around here.

I pulled the head off of an 83 B23F I had many years ago and the pistons were distinctly different. I don't remember if there was a shallower dish, or, no dish at all. It has been over 17 years ago.
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Old 12-05-2017, 03:51 PM   #25
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Quote:
Originally Posted by 2manyturbos View Post
I can't help what Volvo published. I never verified the numbers, just repeated them.

Compression ratio:

B21FT 7.5:1
B23F Manual transmission 1984 9.5:1
All others, 10.3:1.

You will find the same information published in the Bentley Manual and Haynes Manual. It isn't just folk lore passed around here.

I pulled the head off of an 83 B23F I had many years ago and the pistons were distinctly different. I don't remember if there was a shallower dish, or, no dish at all. It has been over 17 years ago.
Well I'm sure there's never an error in anything Haynes, Volvo or above all Bentley published...Even if they differ..Everybody is all right all the time.

But wouldn't you think they the guys who make the pistons and list all that detailed data might possibly know what they are making? Look at all the dimensions and detail..carefully typed cause I don't see the point of photographing the page..

If everybody is always right how are these guys wrong?
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