6 Bolt B20 Forged internals?

[blakemcelroy2000]

Originally Posted by 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.

You think they would take around 300HP? Ive seen one B20 block with a hole in the side of Cylinder 3, so I really don't want that or a lump under the hood if I run up the boost.

[OttoB]

Originally Posted by blakemcelroy2000

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.

http://www.savarturbo.se/?sida=conte...ndelen&sidnr=1

Check those pictures.

[blakemcelroy2000]

Originally Posted by OttoB

http://www.savarturbo.se/?sida=conte...ndelen&sidnr=1

Check those pictures.

Ah, I see. I guess Ill just have to check if I have those. Reading online about the M rods, they look a lot stronger but also heavier. Is the "big end" rod bearing the same diameter as the 6 bolt rod end? Basically, is it possible to run M rods on a 6 bolt crank and then 24mm wrist pin pistons up top? Seems like from what Im reading online there is some serious machining that needs to take place to run this set up.

[cwdodson88]

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

Save this thread

[cwdodson88]

Originally Posted by blakemcelroy2000

Ah, I see. I guess Ill just have to check if I have those. Reading online about the M rods, they look a lot stronger but also heavier. Is the "big end" rod bearing the same diameter as the 6 bolt rod end? Basically, is it possible to run M rods on a 6 bolt crank and then 24mm wrist pin pistons up top? Seems like from what Im reading online there is some serious machining that needs to take place to run this set up.

There’s not. But there is a lot to consider when trying to make 3x HP levels of anything. 2x is easy, 3x is a lot harder.

[142 guy]

Originally Posted by blakemcelroy2000

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.

Beck/Arnley 158-0438 injectors are an exact fit with matching flow rate for the Bosch 036 injectors on the D jet equipped cars. Flow rate is about 550 ml/min @ 43.5 psi. Rock Auto still lists them for about $50 each.

[142 guy]

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?

If you want a slightly dated overview of B20 cams (some may no longer be available), go here:

http://www.1800philes.com/ianr/_superlist_grinds.html

If you are looking for low overlap, the Volvo A, B and C grinds appear to be the winners. If you want to up the lift you could consider some high ratio roller rockers from Yellaterra.

The D cam probably represents the limit for SU carbs in terms of getting a reasonable idle at a normal idle speed. The C grind was the stock cam for the B20B. At an idle speed of 850 RPM the D cam on my B20E results in a MAP of around 55 kPa and on Tuner Studio with a high Res tach wheel you can see that the idle is definitely irregular, particularly if you try to run the idle AFRs at 14.7 or leaner.

The K cam showed up in 1972 or 1973. As noted, it just has slightly less advertised duration than the D cam, lift being the same (the measured duration at 0.05" is the same for both cams) . I don't know that the cam change was related to the drop in compression ratio associated with the F engine. I suspect that the reduced duration may have been more of an attempt to clean up the emissions at idle or improve idle quality.

As noted by others, do not drop the compression ratio by increasing head gasket thickness. This is an invitation for detonation of end gasses in the combustion chamber. If you don't want to fork over the additional $ for a custom MLS head gasket, a head gasket meant for the B20 B engine is your best choice (Elring lists them). The B and E head gaskets both had a compressed thickness of 0.028". However, E head gaskets are no longer available. All head gaskets listed for use on the B20E and B20F are now the thicker B20F gasket which is not the hot ticket for controlling detonation. True B20 B head gaskets will fit just fine on a B20 E or F head. When shopping for head gaskets, be sure to check the compressed thickness. As vendors rationalize their supplies for these older engines they may just start listing the thick B20F gasket for all B series engines.

[blakemcelroy2000]

Originally Posted by 142 guy

If you want a slightly dated overview of B20 cams (some may no longer be available), go here:

http://www.1800philes.com/ianr/_superlist_grinds.html

If you are looking for low overlap, the Volvo A, B and C grinds appear to be the winners. If you want to up the lift you could consider some high ratio roller rockers from Yellaterra.

The D cam probably represents the limit for SU carbs in terms of getting a reasonable idle at a normal idle speed. The C grind was the stock cam for the B20B. At an idle speed of 850 RPM the D cam on my B20E results in a MAP of around 55 kPa and on Tuner Studio with a high Res tach wheel you can see that the idle is definitely irregular, particularly if you try to run the idle AFRs at 14.7 or leaner.

The K cam showed up in 1972 or 1973. As noted, it just has slightly less advertised duration than the D cam, lift being the same (the measured duration at 0.05" is the same for both cams) . I don't know that the cam change was related to the drop in compression ratio associated with the F engine. I suspect that the reduced duration may have been more of an attempt to clean up the emissions at idle or improve idle quality.

As noted by others, do not drop the compression ratio by increasing head gasket thickness. This is an invitation for detonation of end gasses in the combustion chamber. If you don't want to fork over the additional $ for a custom MLS head gasket, a head gasket meant for the B20 B engine is your best choice (Elring lists them). The B and E head gaskets both had a compressed thickness of 0.028". However, E head gaskets are no longer available. All head gaskets listed for use on the B20E and B20F are now the thicker B20F gasket which is not the hot ticket for controlling detonation. True B20 B head gaskets will fit just fine on a B20 E or F head. When shopping for head gaskets, be sure to check the compressed thickness. As vendors rationalize their supplies for these older engines they may just start listing the thick B20F gasket for all B series engines.

That camshaft site is super helpful, thanks! Those Yellaterra rockers are pretty sweet, looks like running those with the stock C grind or Isky VV61 would be a fast setup. What do you feel is more important on a supercharged application? Limiting overlap as much as possible but sacrificing some duration and quite a bit of lift? Or picking a cam with a little higher overlap but with a little more duration and a whole lot more lift?

[cwdodson88]

If your plan is boosted, I’d go for less overlap rather than more lift. Or have a custom cam ground. Blowing your charge straight out the exhaust doesn’t seem like a benefit for the trade off.

[142 guy]

Originally Posted by blakemcelroy2000

That camshaft site is super helpful, thanks! Those Yellaterra rockers are pretty sweet, looks like running those with the stock C grind or Isky VV61 would be a fast setup. What do you feel is more important on a supercharged application? Limiting overlap as much as possible but sacrificing some duration and quite a bit of lift? Or picking a cam with a little higher overlap but with a little more duration and a whole lot more lift?

I have no experience with forced induction on a B20.

That said, as an observation forced induction may be effective at dealing with flow restrictions on the intake; but, you need to be able to get the spent charge out the exhaust and the supercharger / turbo does nothing to help that. The B20 has a particularly crippled exhaust port (lots of threads discussing the problem) in terms of flow. You may find that you need overlap to help you scavenge spent charge out of the combustion chamber. The amount of overlap that is beneficial will probably depend on the boost level. A low boost application may do better with less overlap. More boost may need more overlap to achieve the maximum volumetric efficiency at the expense of poor low RPM operation and poor fuel consumption. So, optimum cam specs will likely depend on the maximum manifold pressure that you are planning for.

As a related observation, you don't necessarily have to trade off lift against duration. If you put high ratio rockers on a C cam the duration and overlap remain the same; but, the lift is increased. However, more lift without more duration typically means faster acceleration on opening and closing which can present some durability issues for the B20 valvetrain. The other thing to consider is that a lot of lift may not be of much value with stock ports. Turbobricks member Canuck did a lot of flow measurements on the B20 head and I think it was he who identified that increasing lift much beyond 0.45 " had exceedingly low returns in terms of flow improvement on a stock head.

The super list of cam grinds did not include any cam grinds from Tinus Tuning (www.tinustuning.nl). It has been a while since I looked at his offerings; but, I recall that he did have one or two B20 cams that were suggested for use with forced induction. If you email him he may be able to provide advice on the best cam for your planned level of boost or advise on what additional head modifications are required to support the level of boost that you are looking for.

Edit:

Unless you are wedded to using a supercharger, you may want to look at what Volvo did with the B230FT engines as a starting point. The B230 has a head design that is not exactly light years ahead of the B20 (its aluminum, has an overhead cam to reduce flailing parts and noise and Volvo finally figured out that having the intake preheated by the exhaust was probably not optimal); but, the ports and combustion chamber shape are still dated - almost as good as the ones on my Honda lawnmower. In turbo + configuration it was good for around 180 claimed hp. If you look at the B230FT cam profiles mixed with the boost level, intercooling, ignition timing and compression ratio you have a starting point that can probably be translated to the B20. Or you could do what other people do and just exchange the B20 for a B230FT which will be much cheaper and then you can start tweaking the B230FT.

[blakemcelroy2000]

Originally Posted by 142 guy

I have no experience with forced induction on a B20.

That said, as an observation forced induction may be effective at dealing with flow restrictions on the intake; but, you need to be able to get the spent charge out the exhaust and the supercharger / turbo does nothing to help that. The B20 has a particularly crippled exhaust port (lots of threads discussing the problem) in terms of flow. You may find that you need overlap to help you scavenge spent charge out of the combustion chamber. The amount of overlap that is beneficial will probably depend on the boost level. A low boost application may do better with less overlap. More boost may need more overlap to achieve the maximum volumetric efficiency at the expense of poor low RPM operation and poor fuel consumption. So, optimum cam specs will likely depend on the maximum manifold pressure that you are planning for.

As a related observation, you don't necessarily have to trade off lift against duration. If you put high ratio rockers on a C cam the duration and overlap remain the same; but, the lift is increased. However, more lift without more duration typically means faster acceleration on opening and closing which can present some durability issues for the B20 valvetrain. The other thing to consider is that a lot of lift may not be of much value with stock ports. Turbobricks member Canuck did a lot of flow measurements on the B20 head and I think it was he who identified that increasing lift much beyond 0.45 " had exceedingly low returns in terms of flow improvement on a stock head.

The super list of cam grinds did not include any cam grinds from Tinus Tuning (www.tinustuning.nl). It has been a while since I looked at his offerings; but, I recall that he did have one or two B20 cams that were suggested for use with forced induction. If you email him he may be able to provide advice on the best cam for your planned level of boost or advise on what additional head modifications are required to support the level of boost that you are looking for.

Edit:

Unless you are wedded to using a supercharger, you may want to look at what Volvo did with the B230FT engines as a starting point. The B230 has a head design that is not exactly light years ahead of the B20 (its aluminum, has an overhead cam to reduce flailing parts and noise and Volvo finally figured out that having the intake preheated by the exhaust was probably not optimal); but, the ports and combustion chamber shape are still dated - almost as good as the ones on my Honda lawnmower. In turbo + configuration it was good for around 180 claimed hp. If you look at the B230FT cam profiles mixed with the boost level, intercooling, ignition timing and compression ratio you have a starting point that can probably be translated to the B20. Or you could do what other people do and just exchange the B20 for a B230FT which will be much cheaper and then you can start tweaking the B230FT.

I am already planning on opening up the "ceiling" on the exhaust ports on my head. One the topic of high lift effecting valve train component integrity, if I was to increase lift with roller rockers, I would also upgrade to stronger retainers, double valve springs, and tubular pushrods. I will check out Tinus tuning however.

[JohnMc]

Originally Posted by 142 guy

Tinus Tuning (www.tinustuning.nl).

[Cromlech]

Really cool project, love the intake/plenum!

[vintagewrench]

A six-bolt crank will work just as well as an eight bolt as least up to 200hp and more with a light flywheel. The one issue with them is the torsional vibration inherent in a four cylinder engine will break the stock flywheel bolts. Switch to new Dana 30 diff ring gear bolts or get a set of ARP flywheel bolts and you should be ok.

Eight bolt cranks use narrower and very heavy rods and narrower crank journals.

This photo shows our B18B crank (same as a 6-bolt B20) after removing all of the external stress risers and semi-polishing it for race prep. In the photo the flywheel runout (in this case a 8.5lb aluminum piece - the original is 22 lbs), and the runout of the center main bearing (only .0005) are being checked. Then it was then reground followed by rebalancing and cryogenic treating

For what you are shooting for the rods should be replaced with aftermarket pieces; either Pauter rods, or Asian. Carrillo rods and bolts are the strongest on the market.

If you use a steel cam gear it can lightened (this one by one pound) and if you use an early steel gear it should be balanced. The recessed hub area and the original lightening holes in these gears usually are not concentric with the bore or the teeth, but machining both of them will remove the imbalance. This gear and others we have checked are off as much a .060"

[blakemcelroy2000]

Originally Posted by vintagewrench

A six-bolt crank will work just as well as an eight bolt as least up to 200hp and more with a light flywheel. The one issue with them is the torsional vibration inherent in a four cylinder engine will break the stock flywheel bolts. Switch to new Dana 30 diff ring gear bolts or get a set of ARP flywheel bolts and you should be ok.

Eight bolt cranks use narrower and very heavy rods and narrower crank journals.

This photo shows our B18B crank (same as a 6-bolt B20) after removing all of the external stress risers and semi-polishing it for race prep. In the photo the flywheel runout (in this case a 8.5lb aluminum piece - the original is 22 lbs), and the runout of the center main bearing (only .0005) are being checked. Then it was then reground followed by rebalancing and cryogenic treating

For what you are shooting for the rods should be replaced with aftermarket pieces; either Pauter rods, or Asian. Carrillo rods and bolts are the strongest on the market.

If you use a steel cam gear it can lightened (this one by one pound) and if you use an early steel gear it should be balanced. The recessed hub area and the original lightening holes in these gears usually are not concentric with the bore or the teeth, but machining both of them will remove the imbalance. This gear and others we have checked are off as much a .060"

Any part numbers on those carillo rods? I am definitely planning on getting the flywheel lightened. Good to know about rebalancing those cam and crank gears.

[vintagewrench]

Originally Posted by blakemcelroy2000

Any part numbers on those carillo rods?

They are longer, light weight and narrower Chevy rods with 1.899 Honda rod bearings. For what you are planning contact them as they have done standard dimension B18 and B20 rods before.