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b20 block questions

I just assumed that he was going to bore it to 92 mm based on his question.

It would certainly make it easier to make a fun-er-er engine..:nod:Moar Torax.:oogle:
but not significantly change things I would suggest..i just don't get too fixated on XXX.z HP
And i don't fixate on motor alone...I say you can't talk motor without referencing gear-set and final drive, since we don't drive engines around, we drive cars.
 
It would certainly make it easier to make a fun-er-er engine..:nod:Moar Torax.:oogle:
but not significantly change things I would suggest..i just don't get too fixated on XXX.z HP
And i don't fixate on motor alone...I say you can't talk motor without referencing gear-set and final drive, since we don't drive engines around, we drive cars.

True - cars are systems. No point mating 200 hp to a 2.90 final drive if you were thinking of having fun!

What car is this B20 going in? What are you using it for? Enquiring minds want to know!
 
The torque you can make with normal aspiration is limited, all you can do is get closer to a theoretical maximum. Room for improvement, but not a doubling or tripling like you can do with boost. Since you can't make a bunch more boost, you just have to improve on the other part of the HP equation, RPM. Torque is nice, torque at double the RPM is twice as nice.

And yeah, I'd say well north of 7000 rpm. Like the Honda S2K engines that have a 9000 rpm redline. You're probably not going to get a square(r) Volvo motor to rev like that (for long), but the higher the better.

I/H/E - Intake/Head/Exhaust. It gets increasingly difficult and technical to make it all flow effectively at higher RPM's.

I think we all get somewhat spoiled with how turbo cars make HP (just up the booooosts!), it's hard to get a really significant increase in HP out of a normally aspirated engine.
 
The torque you can make with normal aspiration is limited, all you can do is get closer to a theoretical maximum. Room for improvement, but not a doubling or tripling like you can do with boost. Since you can't make a bunch more boost, you just have to improve on the other part of the HP equation, RPM. Torque is nice, torque at double the RPM is twice as nice.

And yeah, I'd say well north of 7000 rpm. Like the Honda S2K engines that have a 9000 rpm redline. You're probably not going to get a square(r) Volvo motor to rev like that (for long), but the higher the better.

I/H/E - Intake/Head/Exhaust. It gets increasingly difficult and technical to make it all flow effectively at higher RPM's.

I think we all get somewhat spoiled with how turbo cars make HP (just up the booooosts!), it's hard to get a really significant increase in HP out of a normally aspirated engine.

Agree 100% we get spoilt by boost...but boost is about same volume engining making moare toque and by difinition more hp...the definintion of hp is torque x time --how BIG is the BAND= torque..How many BANGS in a unit of time= HP..Up the first and you up the second...

FLOW is nearly always talked about in PEAK terms and linked to "ability to rev" commonly.
But valves aren't instantaneous at full lift. Nor are engines run at 100% wide open...
The increasingly difficult part is also the increasingly 'spensive part...I've often just shaken my head when people fixate on peak flow at some max lift ---often way beyond what can affordably be pulled off in left and brag about another 5-8cfm at "14mm lift" when you see the flow flatten out at say 11.5mm lift... What % is 5 out of 175? Under 3%...
So is it worth $2000 more for 3% more?
Is it worth $2000 more in a head for 3% more peak---if the car still has a gearbox with canyons between the gears and a 2 car-length 1st gear that'll fall 40-50% revs on a gearchange Like WHAAAaaaaaaaaaaaaaaaaaaaaaaa(cruch!) DUHhhhhhhhhhhh
That is a big problem so little point in having a fap-fest about MAX anything...

(and that's why I look mainly at upping torque to make it so the motor acn "pull' the gearchanges without falling flat on its face. And peak HP be damned to some degree.)
Do what we can do and see how it feels and maybe that's all the guy really wants in the end.
 
True - cars are systems. No point mating 200 hp to a 2.90 final drive if you were thinking of having fun!

What car is this B20 going in? What are you using it for? Enquiring minds want to know!

Since the OP is MIA and I'm familiar with the project I'll try to answer.

He has an early 142 that he's using for 'vintage rallies' that involve spirited driving on paved and gravel roads. It has a 4.30 rear end with a Tru-Trac LSD and he plans on using a T5 trans when the DeeWorks adapters are available.

The engine will be bored .100" over to 3.6" (2100cc) using forged pistons and rods. The F head will get oversized valves, hardened exhaust seats, dual valve springs, a mild port job and be milled to increase compression to 10.5-11:1. He's looking at cams with either .480"/280? or .510"/300?. He has dual DCOE's (45's I think) for induction. I'm not sure what the plans are for exhaust.

I told him to expect 160-175 hp realistically. 200 is a bit optimistic.
 
Since the OP is MIA and I'm familiar with the project I'll try to answer.

He has an early 142 that he's using for 'vintage rallies' that involve spirited driving on paved and gravel roads. It has a 4.30 rear end with a Tru-Trac LSD and he plans on using a T5 trans when the DeeWorks adapters are available.

The engine will be bored .100" over to 3.6" (2100cc) using forged pistons and rods. The F head will get oversized valves, hardened exhaust seats, dual valve springs, a mild port job and be milled to increase compression to 10.5-11:1. He's looking at cams with either .480"/280? or .510"/300?. He has dual DCOE's (45's I think) for induction. I'm not sure what the plans are for exhaust.

I told him to expect 160-175 hp realistically. 200 is a bit optimistic.

I have an NOS B18-B20 'U' cam for $180 plus shipping, supporting mods are shown in the 1979 R sport catalog.
 
U_CamSpecs.jpg
 
I had an S cam in the PV's motor for a while (until a lobe got chewed off, as happens occasionally with these things).

It was pretty fun, nice 'on cam' feel at 3200 rpm or so, pulled pretty well up past 7500. I have an Isky VV81 in it now, which is pretty similar to the S.

There is a noticeable (relative) lack of power under 3000 rpm though, but in use, that's really just a brief moment or two when starting out in 1st, from there on when you shift to a higher gear (when you're at least trying to accelerate quickly, anyhow), you're already over 3K in the next higher gear. That's with an M41's stock ratios, at least, but still, you're never in a dead spot unless you're just puttering along on purpose.
 
Agree 100% we get spoilt by boost...but boost is about same volume engining making moare toque and by difinition more hp...the definintion of hp is torque x time --how BIG is the BAND= torque..How many BANGS in a unit of time= HP..Up the first and you up the second...

FLOW is nearly always talked about in PEAK terms and linked to "ability to rev" commonly.
But valves aren't instantaneous at full lift. Nor are engines run at 100% wide open...
The increasingly difficult part is also the increasingly 'spensive part...I've often just shaken my head when people fixate on peak flow at some max lift ---often way beyond what can affordably be pulled off in left and brag about another 5-8cfm at "14mm lift" when you see the flow flatten out at say 11.5mm lift... What % is 5 out of 175? Under 3%...
So is it worth $2000 more for 3% more?
Is it worth $2000 more in a head for 3% more peak---if the car still has a gearbox with canyons between the gears and a 2 car-length 1st gear that'll fall 40-50% revs on a gearchange Like WHAAAaaaaaaaaaaaaaaaaaaaaaaa(cruch!) DUHhhhhhhhhhhh
That is a big problem so little point in having a fap-fest about MAX anything...

(and that's why I look mainly at upping torque to make it so the motor acn "pull' the gearchanges without falling flat on its face. And peak HP be damned to some degree.)
Do what we can do and see how it feels and maybe that's all the guy really wants in the end.
I was subtly saying the same thing. Peak HP is all about pushing the torque band higher and higher, and unless you can do the New(!) Improved(!) fancy fun things with cams like modern engines can (the Honda VTEC two cams-in-one, or variable cam timing, or variable intake timing separately from variable exhaust timing), like you said, it comes with tradeoff lower in the RPM range.
 

Nice..
Except copy editor didn't catch the "Intake closes before BDC"..I don't think intake valve opens on S cam 49* BTDC and closes 71 before Bottom Dead center..That would be 158* duration.

I think they mean 71 AFTER BDC...49+180+71=300..

With enough static compression that sounds like it would be a very nice, fun camshaft.
but it would need at least 11.0:1 to be fun..
 
I don't think 7000 is revving the piss outta sumpin..8000 yeah:omg::omg::omg:

And whats I/H/E? for us nervous novices??

8K Rev range would be awesome.

I just put a 4.10 rear end with a detroit trutrac in there so that's what I'm doinng for the final drive.

What goes in between is still a bit of a question. Currently, I have an m40 in there. But I have an s10 t5 five-speed that I would love to put in there. I want to use the s10 t5 so that I can try to keep the school bus shifter as close to its stock location and because I want a 5th gear.

The reason for that is because of how I use it.

What car is this B20 going in? What are you using it for? Enquiring minds want to know!

It's going in a '68 142s. I use the car mostly for the vintage car rallies in northern California. And by "vintage car rally" I usually mean the preferred legal term of "self guided tour of California's back roads." But I live in LA. Which means a lot of really buzzy highway miles just to get to the start. The 4.10 was to bring the highway rpms down a bit and I'm hoping the 5-speed will do it a little bit more.

I don't know what gear set is in the t5 though as I haven't quite gotten that far, and I figure I could always add it down the road.
 
Since the OP is MIA and I'm familiar with the project I'll try to answer.

He has an early 142 that he's using for 'vintage rallies' that involve spirited driving on paved and gravel roads. It has a 4.30 rear end with a Tru-Trac LSD and he plans on using a T5 trans when the DeeWorks adapters are available.

The engine will be bored .100" over to 3.6" (2100cc) using forged pistons and rods. The F head will get oversized valves, hardened exhaust seats, dual valve springs, a mild port job and be milled to increase compression to 10.5-11:1. He's looking at cams with either .480"/280? or .510"/300?. He has dual DCOE's (45's I think) for induction. I'm not sure what the plans are for exhaust.

I told him to expect 160-175 hp realistically. 200 is a bit optimistic.

Sorry for being MIA. It's been a bit bonkers in my life lately.
 
I had an S cam in the PV's motor for a while (until a lobe got chewed off, as happens occasionally with these things).

It was pretty fun, nice 'on cam' feel at 3200 rpm or so, pulled pretty well up past 7500. I have an Isky VV81 in it now, which is pretty similar to the S.

There is a noticeable (relative) lack of power under 3000 rpm though, but in use, that's really just a brief moment or two when starting out in 1st, from there on when you shift to a higher gear (when you're at least trying to accelerate quickly, anyhow), you're already over 3K in the next higher gear. That's with an M41's stock ratios, at least, but still, you're never in a dead spot unless you're just puttering along on purpose.


I ended up getting a NOS IPD cam that supposedly has an R-grind on it. I also have a K cam on the shelf. Ideally I'd use one of those. I'll beed to confirm the grind of the IPD cam before I make that decision.

As Hiperfauto said, 200 is the goal but I know it's more pie in the sky than a reality.

As John V has made a solid argument for, I wanted to turbo the engine. But I feel like I was getting project paralysis trying to decide. I'm doing forged rods on a 6-bolt crank with the thought that one day I might turbo. But then there's a whole lot more stuff I'll have to think about, like redoing the rear end and coming up with a better brake solution over the 164 front rotors and calipers.
 
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