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NA performance? Look here.

For DCR calculators to be close enough to use, I'd go for measured intake valve closing. Or calculate it, then go for +/- 5+deg from that to give you a range.
DCR and SCR calculations are just one tool you can use for performance engine building.
The most important thing to do is measure what you have, don't take what someone else has done as truth. Use someone else's measurements to get an idea what's going on, but don't count on them for your
final calcs.
 
culberro said:
For DCR calculators to be close enough to use, I'd go for measured intake valve closing. Or calculate it, then go for +/- 5+deg from that to give you a range.
DCR and SCR calculations are just one tool you can use for performance engine building.
The most important thing to do is measure what you have, don't take what someone else has done as truth. Use someone else's measurements to get an idea what's going on, but don't count on them for your
final calcs.
Click to expand...

I agree, each motor is going to be a bit different. I intend for this tool to be useful for "back of the napkin" math that lets people pick a direction to go in and make a plan.
 
I think it's a great tool for that as well!
The tools needed to do all of these measurements yourself are not expensive ($50?), and it's cool that someone can use measured values.
The "Advertised cam specs" that are listed on the forum are questionable, but it's cool that you included them!
 
culberro said:
The "Advertised cam specs" that are listed on the forum are questionable, but it's cool that you included them!
Click to expand...

Agreed. Even mine could certainly be found to be a little dubious, as the graduation on my dial indicator is 0.001". One thousandth, on an opening or closing ramp, can be several degrees. The only solace I have is that my numbers came out really similar to the guy who did the listing for Calgary Volvo Club. Cam and I have tried to figure out what valve event points the overseas manufacturers use to measure their duration figures. Despite trying a few times with a couple different cams, we really couldn't come up with an answer. The closest we came up with is that it's something like 0.5mm lift AFTER lash, which we have no confidence in. They do seem to be much longer than other sticks when using SBE (Society of Backyard Engineers) standards.


One thing you have to be careful about when calculating your valve events is that you're assuming a symmetrical lobe (opening and closing ramps are shaped identically), which is seldom the case.
 
Updated the first post slightly and added the different "steps/stages" from a later post to it.
 
We had the General Leif on the dyno yesterday with its current configuration: Latest update in the build thread

SETUP:
This is with a wearing lobes, custom reground K cam (12.5mm lift, 259 degrees at .050? lift and 108LSA), 12.4:1 compression, B230E 96.6mm pistons, 43cc chamber 531 head (2.7mm off or so), stock size valves, opened chambers and some (mild?) port work by Robert, pistons set to .010? above deck, .045? Cometic MLS gasket, stock exhaust manifold with very mild port work, 1 7/8? custom downpipe with 450mm long runners before the 2-1 merge into a 2.5? pipe exhaust, stock ignition system with NGK BPR7ES plugs, Lh2.4 custom tuned, red body 1998 GLT injectors (same flow as 850T orange tops but 4 holes), B21F intake manifold with injector bungs added, a 90 degree elbow to a 960 throttle body with an 850na throttle plate and 960 MAF sensor.

We did not touch the ignition tuning this time and are still running around 29 or so degrees max advance like we were with the old setup in 2019 which was an Enem K13 camshaft (12.5mm, 106 LSA and I think 280 advertised duration which must be at some random lift), a 405 head prepped similarly to this 531 but with likely around 11:1 compression or possibly less. We're running 92 octane pump gas with nothing added to it. I have more fine tuning of the air/fuel ratio to do, and we could maybe try advancing the cam gear a full tooth because the final pulls were with the cam gear at it's 5 degrees advanced maximum. The other pull shown for the current setup is with the cam at 3 degrees advanced. You can see it has a little more pull up top, but we would prefer that good torque a little more as we're doing endurance racing! With some ignition and other fine tuning, we might be able to get back to the peak torque we had with the K13 as shown in the comparison chart. Some of the difference between the two new pulls are from it being leaned out in the lower-mid-range areas.

Anyway, not too shabby! We have an AGAP R33-264-14 with 105 LSA going in later this week that didn?t make it in time to be installed before the dyno day. Bummer! We?ll have to make another visit to the dyno some day. Hopefully we don't lose too much more of that lower end torque. If we do, we'll just have to get some ITBs and put on a more modern engine management. Maybe. That might be too much power for what we're looking for at the moment. HAH!
 

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We were happy with it, for sure! Especially how the power hangs even without a fancy intake or exhaust manifold on it. We?re really curious what it?ll do with the AGAP R33-264-14 and 105 LSA camshaft in it now (that?s Race profile, 264 degrees at .050? and 14mm of lift). Maybe we?ll go back for a few pulls on the dyno to figure out where it wants the cam timing and dial in the AFR a little more.
 
shoestring said:
How are you compensating for that much lift on your valve guides? Are you cutting them down or using longer valves or...?
Click to expand...
Both! Well, the guides may be full length and just pushed down a little farther, I?m not 100% certain. The valves are 112mm long. Culberro will chime in with details!
 
shoestring said:
How are you compensating for that much lift on your valve guides? Are you cutting them down or using longer valves or...?
Click to expand...

The valves are VW air cooled race valves, and they?re 112mm long.
The intake guides are installed at 13mm above the stock spring pad (instead of the stock 15.5mm), and that?s just because of the seals. The exhausts don?t need to be set deeper.
The Erland Cox aluminum retainers sit a bit closer to the guides, so that had to be taken into account.

Usually I?d shorten the guides a few mm so they don?t inhibit flow on the intake side. They are tapered as well.
 
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What ^he^ said! Having the smaller base circle camshafts help, too. With our last 14mm lift cam, it had a 33mm base circle. The new one from Agap supposedly has around a 33.5mm one.
 
culberro said:
The valves are VW air cooled race valves, and they?re 112mm long.
The intake guides are installed at 13mm above the stock spring pad (instead of the stock 15.5mm), and that?s just because of the seals. The exhausts don?t need to be set deeper.
The Erland Cox aluminum retainers sit a bit closer to the guides, so that had to be taken into account.

Usually I?d shorten the guides a few mm so they don?t inhibit flow on the intake side. They are tapered as well.
Click to expand...

This is very good to know, interesting. That stock intake guide sure is massive.
 
I taper them down on most builds.
I might just have some custom shorter ones made for the intake side, and have the exhausts get a side parabolic or radius end.
 
Hi my car is 1990 240 glt running a stock B230E with AW71 it came with a VX3 cam in it, probably the previous owner changed the cam before i purchase the car it feels heavy on the low end, after i read couple of threads in the forums i suspect its the cam but im not sure can anyone help or suggest what cam should i use.

Thanks
 
freakymaniac said:
Hi my car is 1990 240 glt running a stock B230E with AW71 it came with a VX3 cam in it, probably the previous owner changed the cam before i purchase the car it feels heavy on the low end, after i read couple of threads in the forums i suspect its the cam but im not sure can anyone help or suggest what cam should i use.

Thanks
Click to expand...
Start your own thread in this section. I want to meet the person who changed a V for a VX.
 
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