6 Bolt B20 Forged internals?

[blakemcelroy2000]

Hey all.
I have a fully rebuilt B20 with an F head. Im starting to think about some future modifications to increase power to a pretty high level with a supercharger, megasquirt, variable timing, some head porting, and a new cam. Looking at the power and torque numbers Im hoping to make, Ive become concerned with the strength of internals. Ive heard multiple opinions, that all 8 bolt cranks and rods are cast and that 6 bolts are forged, or that only penta are forged, or that everything was cast. Anyone know for certain? If they are cast, should I get forged rods? Hoping to make around 300HP atc.

[cwdodson88]

IIRC cranks are all forged, rods and pistons are not until you get into turbo era cars, b21 forward there might have been some forged internals...

Ive been running stock rods in my B20 for the last 4 builds. 10psi, dropped a valve, 16psi popped the HG, 18psi blew ringlands off, 22psi blew ringlands off... At 22psi I was running mid 7s in the 1/8th. With a best of 7.2 on a prepped track and average of 7.6 on the unprepped air strip. so right in the neighborhood of 300 at the crank.

Probably should have opened the gaps up another 2 thou, maybe 4 thou. But oh well.

Forged pistons would be worth the money/effort, and if youre going to spend that kind of coin, a set of forged rods would be a great idea.

[blakemcelroy2000]

Originally Posted by cwdodson88

IIRC cranks are all forged, rods and pistons are not until you get into turbo era cars, b21 forward there might have been some forged internals...

Ive been running stock rods in my B20 for the last 4 builds. 10psi, dropped a valve, 16psi popped the HG, 18psi blew ringlands off, 22psi blew ringlands off... At 22psi I was running mid 7s in the 1/8th. With a best of 7.2 on a prepped track and average of 7.6 on the unprepped air strip. so right in the neighborhood of 300 at the crank.

Probably should have opened the gaps up another 2 thou, maybe 4 thou. But oh well.

Forged pistons would be worth the money/effort, and if youre going to spend that kind of coin, a set of forged rods would be a great idea.

Was the ringland failure due to detonation from improper AF ratio? Or are the stock pistons simply not strong enough to survive the power. Are there stronger retainers to prevent dropping a valve? Looked at some rods and pistons on KG Trimning. Very pricey so Id hate to drop a valve on one.

[cwdodson88]

Originally Posted by blakemcelroy2000

Was the ringland failure due to detonation from improper AF ratio? Or are the stock pistons simply not strong enough to survive the power. Are there stronger retainers to prevent dropping a valve? Looked at some rods and pistons on KG Trimning. Very pricey so Id hate to drop a valve on one.

ringlands were both due to insufficient end gap. The last set probably just barely butted, but at 7k for a lengthy auto-x course, it was bound to break something.

The dropped valves were stock springs/keepers/retainers.

The last ones I burnt the seat/edge of the exhaust valves, but only on holes that had failed ringlands, so who knows, chicken or egg.. but the ring ends were clean, so my guess is heat/expansion pushed it too far.

AFR's are stable in boost 12.1 ish, had been in the 11's, but didnt make the power. Ignition timing could be optimized, but its fairly conservative at the moment. No sign of detonation, and all my spark tuning as been with a set of DET cans, havent heard any noises.

I'm building it again this winter with some forged slugs, a set of forged H-beams, and plan to run 25-27psi on pump gas with progressive 100-400cc/min water meth above 20psi.

The car went through about 40 1/8th mile passes in one day, then another 15 the following weekend with no smoke, no issues, great in boost. So I decided to try the auto-x course, and it sucked. My gearing was way too long for it. So in order to maintain any speed on corner exit, I was in first gear for the majority of the course, and on the limiter way too long.

[blakemcelroy2000]

Originally Posted by cwdodson88

ringlands were both due to insufficient end gap. The last set probably just barely butted, but at 7k for a lengthy auto-x course, it was bound to break something.

The dropped valves were stock springs/keepers/retainers.

The last ones I burnt the seat/edge of the exhaust valves, but only on holes that had failed ringlands, so who knows, chicken or egg.. but the ring ends were clean, so my guess is heat/expansion pushed it too far.

AFR's are stable in boost 12.1 ish, had been in the 11's, but didnt make the power. Ignition timing could be optimized, but its fairly conservative at the moment. No sign of detonation, and all my spark tuning as been with a set of DET cans, havent heard any noises.

I'm building it again this winter with some forged slugs, a set of forged H-beams, and plan to run 25-27psi on pump gas with progressive 100-400cc/min water meth above 20psi.

The car went through about 40 1/8th mile passes in one day, then another 15 the following weekend with no smoke, no issues, great in boost. So I decided to try the auto-x course, and it sucked. My gearing was way too long for it. So in order to maintain any speed on corner exit, I was in first gear for the majority of the course, and on the limiter way too long.

What cam are you running? Ive been trying to find one with very little overlap without any luck. Also, not looking to run the a lot past 6000, so Im trying to not have to modify the head to run double springs, but preferably find some stronger ones with better keepers that would take a potentially higher lift cam.

[spock345]

Originally Posted by blakemcelroy2000

What cam are you running? Ive been trying to find one with very little overlap without any luck. Also, not looking to run the a lot past 6000, so Im trying to not have to modify the head to run double springs, but preferably find some stronger ones with better keepers that would take a potentially higher lift cam.

I've also tried to find a lower overlap OHV cam and have come up short. As you go higher in lift your duration gets a lot longer. The higher LSA and lower overlap cams with higher lift seem to have come about with the OHC cars.

Your B20F should already have a stock D or K cam. Those are already pretty good as far as the factory stuff goes.

[cwdodson88]

Originally Posted by blakemcelroy2000

What cam are you running? Ive been trying to find one with very little overlap without any luck. Also, not looking to run the a lot past 6000, so Im trying to not have to modify the head to run double springs, but preferably find some stronger ones with better keepers that would take a potentially higher lift cam.

I'm running a k cam, similar to a D, its probably one of the lowest overlap stock cams.

The last build I ran iPD doubles and steel retainers, stock valves. Good setup, but something took out the seats. Could have been the porting.... maybe nicked the valve grind. or could have been caused by burning oil.

This next build, I might have Schneider run me a custom cam. Not sure yet. But if I do it'll probably be a 274/240 on 116* lobe centers.

I want to say the k is 264/225 on 112* centers... but I cant remember anymore.

[blakemcelroy2000]

Originally Posted by spock345

I've also tried to find a lower overlap OHV cam and have come up short. As you go higher in lift your duration gets a lot longer. The higher LSA and lower overlap cams with higher lift seem to have come about with the OHC cars.

Your B20F should already have a stock D or K cam. Those are already pretty good as far as the factory stuff goes.

Yup, pretty sure I have a brand new D cam in mine. That saves some money! I saw one of your old forum posts about the argument between D cam and K cam and noticed you mentioning the D cam lowering dynamic compression. Pretty sure the F head is 8.5:1 static CR, but I was going to run the IPD thick head gasket to lower it down even further so that I can run larger amounts of boost. Do you think lowering the compression with the gasket down even further in conjunction with the D cam could push the compression far too low?

[cwdodson88]

Don’t do that. Tight squish, cool burn, crank boost. Less chance of building up hot spots, and running into detonation issues.

I’d run it 0 deck, with a cometic.036”.

I’m running like 9.2:1. Higher compression isn’t exactly the killer of a boosted engine

[blakemcelroy2000]

Originally Posted by cwdodson88

Don’t do that. Tight squish, cool burn, crank boost. Less chance of building up hot spots, and running into detonation issues.

I’d run it 0 deck, with a cometic.036”.

I’m running like 9.2:1. Higher compression isn’t exactly the killer of a boosted engine

You're able to run 22psi at 9.2:1 static CR?! Do you have to run race gas or a huge intercooler? Or is it just timing retard with boost?

[cwdodson88]

Originally Posted by blakemcelroy2000

You're able to run 22psi at 9.2:1 static CR?! Do you have to run race gas or a huge intercooler? Or is it just timing retard with boost?

I'm on an MS2 EMS with ls-coil on plug, so spark is controlled, and yes, slightly retarded in boost.

Not exactly a huge intercooler. It was 10x12x2.5 in a V mounted setup. intake temps were typically within 50*f of ambient during 1/8th mile pulls, and within 80f of ambient at my last auto-x.

The new setup is running an air to liquid IC, and should hopefully keep me at within the 50* of ambient. And a bit of water meth just in case.

These were all on 92 pump gas.

I'll probably end up running some 1850cc injectors this next go around, maybe some 2150's so that I can run e85 and crank up the boost even more. I was thinking that 30-35 on e85 would be fun.

edit: grabbed my specs. Bore 3.538 X Stroke 3.15 X HG .036 X Chamber CC: 58... So its like 9.3 ish.

[spock345]

Originally Posted by blakemcelroy2000

Yup, pretty sure I have a brand new D cam in mine. That saves some money! I saw one of your old forum posts about the argument between D cam and K cam and noticed you mentioning the D cam lowering dynamic compression. Pretty sure the F head is 8.5:1 static CR, but I was going to run the IPD thick head gasket to lower it down even further so that I can run larger amounts of boost. Do you think lowering the compression with the gasket down even further in conjunction with the D cam could push the compression far too low?

8.7:1 with the F head. Actually the same as the B230FT. People will routinely shave the head a bit (~9:1) and go for tight squish on those like with what cwdodson88 is running. Modern EFI should make it much easier to manage boost too.

Dynamic compression effects things like your idle quality and vacuum. So when people pop a OHC K cam into a B230F (9.8:1) and notice a lumpy idle, that is because that grind was designed for a higher compression motor.

The differences between the D and K are practically nothing too. About three degrees of duration. Not enough to feel it. The big thing I've run into is running my car with SU carburetors. IIRC the D and K were pretty much a performance cam that never came stock on a carb'd motor until they put it in the fuel injected ones along with the bigger valves. SUs seem to be very sensitive to vacuum at idle. The stock carburetor cams (B and C) had a lower overlap, higher dynamic compression, and higher vacuum at idle which made the SUs happy on lower compression motors. Putting SUs on an 8.7:1 B20F has given me a bit of a lope at idle due to the low dynamic compression and therefore low idle vacuum, which is a common enough issue. Volvo seems to have intended the D and K to go into higher compression cars or something that didn't use SUs. Raise the static compression thereby raising dynamic compression and the idle should smooth out.

[blakemcelroy2000]

Originally Posted by spock345

8.7:1 with the F head. Actually the same as the B230FT. People will routinely shave the head a bit (~9:1) and go for tight squish on those like with what cwdodson88 is running. Modern EFI should make it much easier to manage boost too.

Dynamic compression effects things like your idle quality and vacuum. So when people pop a OHC K cam into a B230F (9.8:1) and notice a lumpy idle, that is because that grind was designed for a higher compression motor.

The differences between the D and K are practically nothing too. About three degrees of duration. Not enough to feel it. The big thing I've run into is running my car with SU carburetors. IIRC the D and K were pretty much a performance cam that never came stock on a carb'd motor until they put it in the fuel injected ones along with the bigger valves. SUs seem to be very sensitive to vacuum at idle. The stock carburetor cams (B and C) had a lower overlap, higher dynamic compression, and higher vacuum at idle which made the SUs happy on lower compression motors. Putting SUs on an 8.7:1 B20F has given me a bit of a lope at idle due to the low dynamic compression and therefore low idle vacuum, which is a common enough issue. Volvo seems to have intended the D and K to go into higher compression cars or something that didn't use SUs. Raise the static compression thereby raising dynamic compression and the idle should smooth out.

Yup, currently running SUs on my B20F until I can afford to do my big conversion. Definitely seeing that lopey idle currently. Oh well, car still runs as smooth as a swiss watch at 1k rpm and above.

[blakemcelroy2000]

Originally Posted by cwdodson88

I'm on an MS2 EMS with ls-coil on plug, so spark is controlled, and yes, slightly retarded in boost.

Not exactly a huge intercooler. It was 10x12x2.5 in a V mounted setup. intake temps were typically within 50*f of ambient during 1/8th mile pulls, and within 80f of ambient at my last auto-x.

The new setup is running an air to liquid IC, and should hopefully keep me at within the 50* of ambient. And a bit of water meth just in case.

These were all on 92 pump gas.

I'll probably end up running some 1850cc injectors this next go around, maybe some 2150's so that I can run e85 and crank up the boost even more. I was thinking that 30-35 on e85 would be fun.

edit: grabbed my specs. Bore 3.538 X Stroke 3.15 X HG .036 X Chamber CC: 58... So its like 9.3 ish.

V mount in a 122? Or are you driving an P1800? Also, where do do your source your injectors? Looks like finding new stock Bosch Djet injectors is pretty expensive. Any other vehicles injectors work? Thanks for all the valuable info.

[cwdodson88]

Yep, v mount in a 122. The current set are 1000cc dekas. I’m running k-jet holders instead of d-jet. They have a tapped boss that I used to mount a custom fuel rail to. I’ll see if I can post something that shows the last setup and the current setup.

[cwdodson88]

Here’s some pics of the newest setup. Awic and a Borg Warner efr7163.

[blakemcelroy2000]

Originally Posted by cwdodson88

Here’s some pics of the newest setup. Awic and a Borg Warner efr7163.

Wow!! Almost didn't see the b20 under all that!! I didn't realize you were running an Air to Water setup.

[cwdodson88]

It’s a b20 for sure… I’ll try to find the pics of the V mount.

[mrjaybeeze]

All B20 or B18 rods and cranks are forged and plenty strong for whatever you are able to throw at them.
It simply does not exist cast cranks or rods for these engines.

[cwdodson88]

And I stand corrected. They are forged rods. But there are differences between B18, Early B20, and Late B20. So take that into account. Also, B21 rods will fit. And I believe this was what Jens Gustafsson was running in his 500 whp B20.

http://forums.turbobricks.com/showthread.php?t=83476

[JohnMc]

I ran 'lightweight' B18 rods in my PV's motor (not boosted, about 160 - 170 HP) for a long while. When I had it apart to replace a cracked piston, I noticed odd wear marks on the rod bearings, right where they have the thinnest metal on the big ends - right where that red arrow is pointing in the last picture. /\ /\ /\
Not a whole lot of wear since the motor had been built, but it had shiny spots right there, seemed clear that the rod big ends were flexing there under stress.

Of course, the B18 rods themselves never caused any issues, but I put it back together with slightly heavier set of B20E rods.

[cwdodson88]

Here’s the best pic I have at the moment of the old v mount setup. And then the front mount that followed it… this thing has been through so many renditions…

[OttoB]

Rods from 74-80 B20/B21 are forged, but the material was not that good for high rpm engines. Better rods were introduced 80/81. There is cast "M" letter on big end.
These goes together with 8-bolt crank.

"Best" rods for 6-bolt crank were early (69-70) B20 rods. Those had long number in the beam.

[blakemcelroy2000]

Originally Posted by cwdodson88

And I stand corrected. They are forged rods. But there are differences between B18, Early B20, and Late B20. So take that into account. Also, B21 rods will fit. And I believe this was what Jens Gustafsson was running in his 500 whp B20.

http://forums.turbobricks.com/showthread.php?t=83476

Don't B21 rods use the larger diameter wrist pin? So you'd need custom pistons to fit the bore of a B20? Im not really interested in getting my engine bored out to fit B21 pistons.

[blakemcelroy2000]

Originally Posted by OttoB

Rods from 74-80 B20/B21 are forged, but the material was not that good for high rpm engines. Better rods were introduced 80/81. There is cast "M" letter on big end.
These goes together with 8-bolt crank.

"Best" rods for 6-bolt crank were early (69-70) B20 rods. Those had long number in the beam.

Like a number stamped into the rod surface? Ill look when I take my oil pan off to replace a gasket if I have those.