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Discussion Starter #1
There are lots of ways to improve the performance of our B18 and B20 engines--and even more ways to do everything wrong. My question: Why do people not post on this topic? I would very much like to know what mods are successful, and those that are not.

An example: Has anyone had experience with the twin-cam, 16-valve head now being offered as a modification to the B18/20? The concept makes great sense, but execution could be fraught with pitfalls. Has anyone made the conversion? Was it successful? Do you lose low-end torque?

Here is a link to the Grainger and Worral site: http://www.gwcast.com/en/2014/01/01/new-cylinder-head-historic-volvo-range/

How about some other thoughts or comments? Another example: The 123 distributor sounds great in concept, yet many users have had trouble with it. Why? Was it because they didn't know how to program it properly? Did they simply pick the wrong curves? Did it fail? Comments, please.

I would like to think that we could get a little deeper into performance mods for the B18/B20. I have recently been educated on the futility of simply increasing displacement as a means of increasing torque and power. Do we all know this? If we do, why do we keep punching out bores and increasing stroke, while ignoring the head?

Here's another: Which (if any) head is best for a carbureted engine? What modifications are most appropriate for specific applications?

And this: Is there a 'best' solution to the Weber DCOE sidedraft conversion? If so, what is it? For example, I have seen several 'solutions' to the throttle linkage problem, and all seem crude in comparison to the original SU linkages. Is there a place where we can buy a good, reliable, Amazon-specific linkage kit? How about the issue of interference between Weber sidedrafts and the RF fender? (Incidentally, I think I have finally found a good commercial solution to the problem, but no one on this side of the Atlantic seems to know about it. Is anyone interested in the answer?)

Come on, everyone. Let's talk about more than headliners, tin worms and effed-up wiring. The Amazon is a fine classic, and deserves more attention than we are giving it.

Dan
 

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I'd like to see more here, too. For better or worse, though, there's already so much information available 'out there' that about all that could happen would be the compilation of existing info. Largely.

I doubt anyone with experience on that 16v head is sitting quietly. Those things are expensive enough that you could execute just about any level of modification anyone's ever tried. Not to say that it isn't awesome - it is - but I don't expect there will be a lot of those around for a long, long time. If ever. You can have that power output for less money, which has me thinking that the only real market for this head will be with racers who can get the thing homologated (if it isn't already). I haven't yet seen any dyno sheets for those heads, so the horsepower claims [as far as I'm concerned, anyway] are still speculative. If that info's out there, I'd love to see it.

Increasing displacement generally increases torque. Without proper head modifications, the result is far less significant. People still do this because lots of us don't know better and still think, simply, that "there's no replacement for displacement."

It's hard to get a good answer for a question as broad as "which head is best." Before anyone can answer that, they'll want to know the intended use of the engine, what grade fuel is available, what your budget constraints are, etc. The simple answer is "SUHS6." But that's just my answer.

I'm not sure what throttle linkage problem you've seen - I've run DCOEs on three or four old Volvos and not had any real problems with the linkage. You probably won't find an Amazon specific setup, but there are some pretty good universal kits available that nicely merge with the original throttle bits. I like this one:

http://www.piercemanifolds.com/product_p/pm3702-l.htm

If you don't want to alter the inner fender, you can use a shorter intake manifold, like the Warnerford. Your fuel atomization/flow/mix/magic won't be as optimized as with the longer manifolds, but not cutting required. I have one of these manifolds I'd be happy to sell, if you're interested.

Thanks for posting. Hope to see more conversation in this arena.

Cheers -

Cameron
Rose City
 

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Discussion Starter #3
Ahhh....

I was sure it would work--bringing another enthusiast out of the shadows, that is. I am a long-time Amazon afficianado, but left the fold for some 30 years until just recently, when my son and I bought a 123GT to restore. My frustration is that there are a few very knowledgeable Amazon/B18/B20 guys here in the states (e.g., Phil Singher), but nothing like in Scandinavia. So I have been scouring the web for resources, some of which have turned out to be pretty obscure. An example: I was on the verge of having intake manifolds for Weber carbs built to my design, so as avoid the fender-cutting problem. Fortunately, I finally found Amazoncars.co.uk, and it turns out that they make upswept intakes which clear the fenders. Their motivation was quite different--they were trying to avoid the steering column on RHD drive cars--but it is perfect for what I want to do. Similarly, you just provided me with the hard linkage that I have been looking for (I don't want to use cables).


So thanks for replying with good information. Let's see if we can get more discussion going on the topic of "pushrod performance." I'd like to see if we could expand it a bit, and find some data on the twin cam 16-valve head. Incidentally, do you know how much it costs?

Best regards,

Dan
 

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Dan, don't assume that there's a lot more expertise in Sweden, although there probably are more competent B18/20 builders specifically. There's no substitute for doing one's own development -- otherwise, you're just trying to duplicate what worked pretty well for someone else, rather than trying to top it. I actually got the concept for our current head porting from an Australian builder, and we've been improving on what he's done ever since. My friend Don and I did an awful lot of research into what Swedish head porters were doing and what sort of flow numbers they were able to get. Our prototype matched the best of them.

There seems to be a lot of standard practice over there that may work in a certain context, but not if you change the context. Lots of builders automatically put in the largest valves that will fit, which may or may not compensate for non-optimum port work. I find that anything larger than the stock 44mm intake / 35mm exhaust costs torque -- the best flowing street head we've done to date was a B20 carb head, with 42mm intakes. We're just finishing up a full-on racing head, and it has stock-sized valves (although they are not the stock valves). I don't have the latest flow numbers, but a few weeks ago they topped anything I'd seen from Sweden and still had room for more improvement.

In 2000 / 2001, I built a B20 using a Swedish-ported head, Swedish cam, Swedish header and other Swedish parts, being advised all the way by a Swedish builder with 25 years experience. That was w-a-y more than I would have had any clue how to do on my own -- for a few years, I really thought that was about as good as it got. I learned a lot from it, but as I continued to do my homework -- research and testing -- I also learned there were a lot of mistakes in it. What I'm building nowadays is really quite different.

Engines are just engines wherever you go, and there is nothing at all special about the B20. Read David Vizard on making a small-block Chevy perform, and you'll find a lot of it applies. There was an builder in England who had a website (now gone, unfortunately) with a wealth of theory that I found extremely useful, even though he was working on English Fords and such. Learn from other peoples' mistakes as well as your own (and I built some really bad engines early on). For instance, the early Ford Boss 302 had intake runners that were too large, so it made gobs of power at the high end but little below -- they rethought that, lost a few HP at the redline and had a car that was quicker under almost all conditions.

Performance is all about getting 1% here, 2% there, etc. It's about getting it all to work together in harmony. It's about scaling engines to fit differing budgets and differing needs. There are many, many books and articles on the subject, and yet different builders build engines differently. I'm happy to answer any questions about how I do it these days and why I think that's best. Then I hope some guy comes along and tells me why that's all wrong -- I may or may not agree, but it'll give me something to think about that may or may not cause me to make changes. It's an ongoing process :)
 

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Agree! We need more "fun discussions" in here. I think this topic is taken too seriously or people only post here when they are going to do a rat-rodded, hot-rod, or race-built motor. That shouldn't be the case. Some of us like to perk up our street rides and get the most out of them.

Isn't the B20F head (FI) a good head to run if you don't plan on doing any porting or increasing valve size? Just plug the injector ports and you're good to go.
 

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I don't know right now which head flows best in stock form. I don't keep the flow charts -- they go to customers along with their engines. I do have the chart for the latest B18 head we did here (all the B20 types flow a bit better stock):

Intake baseline:
119 CFM @ .250 lift
114 CFM @ .400 lift
93.2 CFM average over all lifts

Intake ported:
112 CFM @ .250 lift (actually down a bit)
149 CFM @ .400 lift
105.8 CFM average

Exhaust baseline:
78 CFM @ .250 lift
86 CFM @ .400 lift
63.9 CFM average

Exhaust ported:
99 CFM @ .250 lift
121 CFM @ .400 lift
91.9 average

The average numbers are a lot more important than the peak numbers as far as predicting performance gains. We're looking for the exhaust average to be around 75-80% of the intake average on the bench to produce the most area under the torque curve, which is again much more important than peak torque or HP numbers for street performance. You can see how the stock heads are way under that due to the poor exhaust flow.

I should have numbers on a full-on B20 race head in a few days -- will post those when I do.
 

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I found a copy of another chart that I didn't send to the customer because it doesn't have the baseline flow on it. This is a street B20B head with stock valves. You can see how much better it flows than the B18 head:

Intake ported:
130 CFM @ .250
172 CFM @ .400
121.3 average

Exhaust ported:
110 CFM @ .250
132 CFM @ .400
97.0 average
 

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Vintage racing head on a B20E casting:

Intake ported (I don't have a reading @ .250 for this one):
118 CFM @ .200
164 CFM @ .300
180 CFM @ .400
184 CFM @ .500
137.6 average

Exhaust ported:
99 CFM @ .250
125 CFM @ .400
95.8 average

So, I'm happy with the intake flow, and a bit disappointed by the exhaust flow. This may be due to the shape of the non-stock valves we used, a slight difference on the back cut, or who knows what. It may not be significant in actual use. This is for Jim Perry's P and B Motorsports P1800, which has been getting podiums with its current head. We'll have chassis dyno results for it's current engine / header setup compared to the same engine with the new head and different header by the end of January. Lap times will ultimately tell the story -- Road America is Jim's "home" course, so he's been very consistent there in the past.
 

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Dyno runs are unfortunately delayed for about two months. My machine shop erred on one of the dimensions I'd given them, so there's a feature that needs to be enlarged (fortunately, they didn't take off enough metal rather than too much). Last season's head turned out to be cracked, so that version of the engine will not see dyno time -- no comparison tests.

Lap times...
 
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