So my info was 500 rpm off, the 2zz-ge is rev limited to 8500 in the Elise, oops lol. Still a high RPM the OP is looking for. Don't know if the internal specs will help any now but I'm glad I mentioned it since it has brought up some good information about "Square" engine characteristics. I had been wondering about the different characteristics of different stroke/bore setups, just haven't got around to researching

Don't forget better flame travel too! Which, Larry (Endyn) seems to think is just as or more important as VE.

Sorry, as I said to Pyro it's 8500 rpm for the 2zz motor. Don't know how that works into the equation now

 

Just fine, definitely more great information to look at.

I was looking at about an 8500 rev limit as a goal just not sure if that is feasible. I realize now the difference between 8500 and 9000 is quite substantial but at the time I was throwing a rounded number out there just mainly for specs to look at as 9000 was more than I am aiming for so is a good foundation for "longevity".

I'm thinking custom pistons maybe in order.

I'll sit down and work the acceleration formula on the 2ZZ motor specs and see what it turns up. Same with the B18C.

I have a suspicion the acceleration is surpassing the 100,000 feet per second per second. and the rod angles on the B18C I think are a bit sharp due to the R/S ratio.

This is the Victory Library segment that brought this last bit about:

Z = M²*× S (1 + (1 ÷ 2n)) ÷ 2189	Z = M² × S (1+(1 ÷ 2n)) ÷ 169007.8506
Z is piston acceleration in feet per second per second	Z is piston acceleration in meters per second per second
M is Revolutions Per Minute	M is Revolutions Per Minute
S is Stroke in inches	S is Stroke in Millimeters
n is Rod to Stroke ratio	n is Rod to Stroke Ratio
2189 is a constant	169007.8506 is a constant
100,000 f/s² is a safe limit but will cause ring flutter on 1/16" rings.	30480 m/s² is a safe limit but will cause ring flutter on 1/16" rings (1.5875mm)

Yeah, the 2ZZ motor is a piston acceleration of 4974.31 m/s² which is way over the 30480 limit Victory Library suggests. (1 ft/s² = .3048 m/s²)

I'm thinking the con rod bolts need to be upgrade as well as the wrist pins and forged pistons is likely a must even though I thought I saw something about a "different" casting was used on the B18C which I suspect will fall under the same extreme acceleration.

 

Ok so, just to recap, because this is a lot of info, but it looks like Victory Library is suggesting a "safe" piston acceleration. Yet now you find that, using their equation, both Honda and Toyota have engines that greatly exceed those piston speeds. Is that correct? Just want to make sure I have that right.

If that is right, then I may be inclined to disregard Victory Library's recommendation and instead look to Honda's great engineering on this topic instead

 

Not piston speeds but acceleration. But yeah, Victory Library's recommendation for acceleration is lower than what both Honda and Toyota have pulled off.

Piston speed itself was fine with the recommendation of forged pistons up to about 9000 rpm. It's the acceleration and then the deceleration that was being exceeded.

I am also taking into consideration that these formulas and recommendations are based on domestic motors with their cast iron blocks etc.

I'm still not sure what the secret thing is that is allowing the all aluminum Toyota and Honda motors to exceed that acceleration barrier that's been the demise of domestic motors.

From my understanding though, Honda did hand assemble the JDM B18C and used some sort of special tightening on the rods and quite likely the mains.

So I can only assume not only did they use proprietary tools but they used upgraded studs.

I also believe the type r used a valved intake manifold so it could have both lower and high rpm torque by changing runner lengths, short and fat for the high rpm and long and narrow for the low rpm.

I did find this tidbit on Crower's glossary page which defined what they mean by Lobe Center:
The angular displacement between the center line of the intake lobe, and exhaust lobe of the same cylinder. This factor may be altered in order to ‘fine-tune’ the combustion chamber. For example an engine using the general lobe center of 110° would have a split overlap timing of 40-80 80-40. If for some reason, more low end power plus a cooler combustion chamber were desired, the lobe center could be changed to 105°, which would give the timing of 45-75 75-45 using the same cam master. Some high nitro, blown engines, may use a 100° lobe center cam which would give more combustion chamber cooling, in order to accommodate the high heat of the nitro mixture. A 340° cam with a 100° lobe center would have a timing of 70-90 90-70..

So earlier when I assumed it meant the center of the intake lobe, it's actually the center between the centers of the intake and exhaust.

It took me a bit to figure out how they got the cam timing from the 110°.

Based off the 340° with Lobe Center of 100° equaling a timing of 70-90-90-70 I sat down and tried to decipher the math that fits this. So 340/2 is 170° minus the 100° is the 70° BTDC the Intake valve opens. Then to get the other end you have to remember that the 340=70+180+Y. So Y is 90.

I think I ran into another site that was saying duration of 300° with an LSA or in crowers case lobe center of 110° created a timing of 40-80-80-40.

This would fit the above so the 63441Y should have a max duration of 300. Which on the specs is the exhaust lobe of 302 advertised at 0.010". The Vtec lobe is 292 at 0.010"

The problem is what is the total duration of the lobe starting at 0.001"? I would think this is where the lobe starts to leave the base circle.

I believe I will have to email crower to get the actual valve timings of the 3 NA cams they show for the D16Y8 and go from there.

It's still good to see that I really miscalculated IVC at a really early 27 degrees. Most cams I see typically have an IVC of 60+ degrees ABDC.

Baby steps... I'm just glad I feel like I actually am making a little progress in the comprehension of it all.

Cheers

 

I've emailed crower to see what the cam timing is for all 3 NA cams 63441Y, 63442Y and the 63443Y.

Looking at teh 3/4 Race cam on Brian Crower site, they have this cam card:



It shows IVC at 43.5° but in small print, "timings correct for 0.050" lift".

Doesn't that mean the valve is open 5/1000 of an inch? Meaning not actually closed?

I swear if it's one thing that is totally convoluted it's the camshaft specs. The formulas are already going to be a rough estimate, but what good are they if you can't get accurate event timing such as when the intake valve is actually closed. Mostly closed means it isn't creating pressure.....

Can anyone enlighten me here?

 

.050" is fifty thousandths of an inch or 50/1000 of an inch.
It's just letting you know what the timing specs are when the valve is lifted .050" off the valve seat.

.050" is kinda like the standard when measuring Valve durations.
One company might claim 280 degrees of duration but at. 010" valve lift.
Another company may claim 270 degrees of duration at. 050" valve lift.
In reality, the 270 cam would have more duration than the 280 cam since they started measuring earlier in the valve opening cycle...

Think of a drag race with one car starting at the 60ft Mark and beating the other car starting at the tree by 10 feet...
It crossed the line First only because it started earlier. Bad analogy probably.

I think cam companies use various" starting points" to make a cam seem larger than their competitors and also to make it harder to copy their specific grind of a cam...
So You may see an "advertised cam Spec" and then the real cam Spec when it gives you the @ .050" values...

Hope that makes sense. At least that's how I understand it. Perhaps someone with real camshaft knowledge will chime in and correct me if I'm wrong.

 

"Advertised Duration" can be the duration at any lift the seller decides to use. Some use .004", some .006", some .020", and some use the lash point. Unless you know at what lift the company selling the cam is using to measure "Advertised Duration", the numbers are useless.


Its funny when people tell me they are running a 302 duration camshaft. I'm like LOL Wut..?

 

There's nothing special, they just measured bolt strech which is more accurate method when you preload bolts and studs. "Type-R" rod-bolts have spots for strech gauge, that's all.

Nope.

 

I get that, I guess I have been putting my mind to it incorrectly. I guess I am just to base everything off the 5 thousands of an inch lift for IVC events. It won't give you the real effective stroke but it will be consistent from cam to cam for evaluation. I think that's where I've been getting hung up and not moving as I'm looking for the actual IVC event without actually having the cams in hand and degreeing in person.

Yeah I was confusing the dual runner GSR intake manifold. For some reason I thought it was the one used on the Type R.

And thanks for the clarity on the hand built methods of the type r. The bit I stumbled across about it (an interview maybe?) didn't go into details of what was done just mentioned they used "special" methods other than the average mechanic's way of torque wrench.

I'm guessing for us normal joes, ARP studs and ARP lube and using ARP specs is going to be the most accurate method without having access to a stretch gauge.

 

That's what it's all about. Having a standard to measure off of.
Different Companies just use different measures sticks.

 

Stretch gauges aren't too expensive. They are more accurate. But honestly I've never ever used one and I've never had any engines come apart yet lol. (Knock on wood) Not just Honda engines and both stock and performance builds.

I will prob get one one day though just because lol.

 

lol thats a mighty big cam, must have variable piston reliefs.

alot of this thread is interesting, but wouldnt have anything to do with building a off the shelf engine like youre doing. the first thing to choose isnt the cam, its the goals. then you figure out what displacement youre going to need to run those goals paired with the cam. trying to figure the lsa and everything on a single cam is pointless, since you cannot do anything to change it, youre pretty much stuck with manufacture specs. one of the beauties of running a single cam is you never have to worry about lsa and v2v....ever, if the cams designed right/

 

The reason to locate IVC is so to compare different company cams to see the one that best suits the goals. Or am I totally off base?

Originally I was going about selecting the pistons to go with the rods in the block before I had even looked at cams.

Now I'm trying to isolate the cam that will best work for the power band I would like to have. I already have a pretty good idea of my goal which is more in the mid to low upper power boost with hopefully the least amount of damage to the low. I don't mind it falling off at the very top.

The only parts that are pretty much situated is the 3 mm longer rods and the block/crank and head. The pistons I originally thought could be stock honda pistons but now am not so sure as the high dome seems to hurt flame front and also scavenging etc. So the upped compression may not be enough to make up for the damage to the flame front and scavenging. Also with the longer rods, there is a loss in the stroke, but will go higher rpm.

Brian Crower makes it easy by providing the cam card so you have the IVC degrees so you can do your index numbering with the formulas, Crower on the other hand isn't providing that and I'm not finding a solid way to translate the information they do provide into the IVC event. I emailed sales but haven't heard back so I may try again.

The cam will likely tell me just what kind of pistons I need. But without being able to get the indexing numbers to compare the cams, picking the right one seems out of reach. Also even with one cam, you have LSA options as Crower does offer a custom grind cam. I'm sure you can specify more or less LSA to suit your needs.

I was hoping someone could actually guide me where I'm struggling with the math or the cam info and how to utilize it but things don't always go as one would like.

Sometime this weekend I will do up the numbers for the two Brian Crower options or 3 options.... And see how the results turn out. Then I will have to wait for a response from Crower to compare their cams on paper.

From there I can start looking at the other parts of the motor.

 

Estimating intake closing point
If the intake closing (IC) point isn't known, it can be calculated:
Divide the intake duration by 2
Add the results to the lobe separation angle (LSA)
Subtract any ground-in advance
Subtract 180

Using that the Crower 63441Y with 228° vtec and 197° pri/sec and LSA of 110° has an IVC vtec at 44° and pri/sec at 28.5°.

Crower 63442Y with 235° vtec and 204° pri/sec and LSA of 110° has an IVC vtec at 47.5° and pri/sec at 32°.

Crower 63443Y with 239° vtec and 204° pri/sec and LSA of 110° has an IVC vtec at 49.5°and pri/sec at 32°.

Converting the B7 stock into inches is:
Stroke of 84.5mm=3.32677"
Bore of 75mm=2.95276"
Rod of 134mm=5.27559"
PM3 Piston Com Height of 30.7mm=1.20866"
PM3 Piston Di/Do of -1.5cc=-0.0915356161ci

B7 Com Cham of 38cc=2.31890228ci
Y8 Com Cham of 32.8cc=2.00157881

Z6 Rod of 137mm=5.39370"

PMS Piston Com Height pf 27mm=1.06299"
PMS Piston Di/Do of +4cc=+0.244094976ci

P08 Piston Com Height of 27.4mm=1.07874"
P08 Piston Di/Do of -4.50cc=0.274606848ci

0.027" Head gasket volume = 3.02978707 cc = 0.184888951ci

SE = (S ÷ 2) + R + ((S ÷ 2) × cosA) - SQRT ((R²) - ((S ÷ 2) × sinA)²)

SE is effective stroke

S is the nominal (full) stroke in inches

R is rod length in inches

A is crank shaft angle in degrees ABDC (0-90°)

SQRT is square root.

Radians = Degrees × .017453, or Degrees × Pi ÷ 180.

V/P = VE × CP × N × .3%

Symbol	Meaning	Definition or Calculation
B	Bore	Piston diameter, in inches
S	Stroke	Full (nominal) crankshaft stroke; TDC to BDC measurement (180° rotation), in inches
SE	Stroke, Effective	Stroke measured from intake valve closing point (less than 180°) to TDC [always less than “S”
VN	Cylinder Volume, Nominal	B²*× S × .7854 (1 cylinder)
VE	Cylinder Volume, Effective	B²*× SE × .7854 (1 cylinder) [always less than “VN”]
N	Number of cylinders	(4, 6, 8, 10, &c.)
AP	Atmospheric Pressure	14.7 psi @ sea level (zero elevation); use the correct lower figure for higher elevations
CRE	Compression Ratio, Effective	CRE = (VE + VC) ÷ VC [always less than “CRN”
CP	Cranking Pressure (absolute)	CP = (CRE1.2*× AP)
GP	Gauge Pressure	GP = (CRE1.2*× AP) - AP. To predict gauge pressure, subtract atmospheric pressure (14.7 psi @ sea level, &c.) from absolute pressure.
V/P	Volume/Pressure Index	V/P = CP × VE × N × .3% (.3% or .003 is a correction factor to return a useful 2 digit number roughly proportionate to torque)
VC	Chamber Volume	VC = VN ÷ (CRN - 1). Total volume (1 chamber) above piston @ TDC, in inches.
CRN	Compression Ratio, Nominal	CRN = (VN + VC) ÷ VC

The last two formulas are cyclic so are useless. This basically kills the whole process.

Also interesting that when I add up all the volumes and then divide by the compressed volume I get a compression ratio of 7.x:1 for the stock B7. And yet both zeal autoworks and the FSM show the stock B7 at around 9.23:1. The only area I don't have a figure for is the tiny space around the piston to the top ring.

Even when I took 38cc plus the cc of the head gasket, then add it to the volume of the cylinder based on stroke, I get 7.6669:1. The 1.5cc of the valve reliefs wasn't factored in but really it's going to be the same on both the compressed and uncompressed so I don't see it changing anything.

Based off the FSM numbers for the stock B7, I can't get the same 9.23:1 Static Compression Ratio.

I'm thinking the math and information readily on the internet is misleading. Which in turn is making this whole great scheme of things pretty pointless.

I am about to throw in the towel and just get the parts I was originally planning on, and just seeing how it turns out.

Trying to get math to get a baseline just isn't readily available on the internet, everyone has some part screwed to hell. Or they have a calculator that you can't tell what the hell it's doing.

Frustrating to say the least. On the plus side I suppose, I have more specs on all the parts than I had when I started.

 

You need to be an engineer.

Don't beat yourself up over all the formulas.
The dome volume of the piston takes into account the valve reliefs and the tiny area above the top ring I think.

I wish I knew more about D series. I'm sure there are all sorts of combos to be had with OEM parts.

 

just thought I'd throw this out there: I once saw a back to back dyno test with a turbo b16a. The only change was the length of rod and pin height to compensate. They started with stock dimensions and then they put in a longer rod combination. The longer rod lost power across the entire graph. Not much, but some everywhere. Maybe it could've been made up with more safe rpms or cam phasing. Who knows?

Also, I do business from time with Larry at Endyn. Over the last year or 2 he's been working with Nissan, building heads and motors for some v8 road course series. Anyway, he likes to share stories with me. One time he told me about an argument he got into with the nissan engineers about rod length and deck height. The engineers kept saying that he needed long rods and a tall deck to make power. He said that the series is limited to 7000 rpm rules and that there wasn't enough piston speed to move air through the head like he wanted. So, he ended up cutting the deck way down and running a much shorter rod to get the peak piston speed higher. The motor made much better power that way. He then told me that "the Nismo engineers over at Nissan don't know $#!+ about building naturally aspirated motors" LOL

 

Thanks, it's all good. I got a reply back from Victory Library so have an understanding of a couple of things. I actually do have enough information to play with the math and will at some point.

I think I just have worked myself into one of those points where you've been staring at the problem sooo long that all you see is dead ends. I know from experience when that point is reached, you just have to drop it and walk away for awhile, come back later and you usually see a new path or method.

I'll be back to this soon.

Yeah, that makes total sense. That's what stroking a motor is, you shorten the rod length so you get more speed from what my research shows. Basically you get more volume and faster piston speeds.

I can't really do that with this motor unless I want to spend more on custom rods than a new motor. The angles and the thinness of the current rods has them limit rpm to a max of 6500 or so. I'm wanting to switch to vtec which typically runs to higher rpms. I know I'm going to lose a bit of piston speed with the 3mm longer rods and will lose a little power on the existing graph, but I believe will make up for it by lengthening the power band to much higher rpm ranges and adding vtec to the none vtec motor.

I'm wanting to get to an 8000 rpm limit to satisfy a 7700 rpm redline. I believe shot peening the stock 137mm Z6 rods will do this as without the shot peening they normally run to 7200 rpm naturally.

This is providing another 1100 rpm or so to the power band and the vtec will stop the plateau that is present from 5200 rpm on up on the stock D15B7 motor.

Currently the D15B7 motor only produces solid power from 4000 rpm - 5200 rpm. After 5200 rpm it's flat lined and no more oomph to give. I would really like to enjoy more climb in power as the RPM continues to rise. Vtec alone will do that, but I figured if I'm modding the engine, might as well have some fun and learn a thing or two.

On a side note: My goals are not a specific HP goal. HP is the open variable. The goals are a semi set power band range. I am looking to have the power band in a specific area of the rpm range. I'd actually like peak power to occur just a touch before redline. If it starts to flatline a few hundred rpm before the end of the rpm range, I will be quite happy. I don't want to feel like I need to get more RPM to squeeze out any more power. Sort of like driving speakers, I don't want distortion, I just want all the power the speakers can handle just before distortion. And I don't want to feel like a premature ejaculation man like the D15B7 does stock. It hits peak power way too early and is all spent long before the thrust is threw.

 

Well, in his case he was not changing the stroke of the motor. He had to work with what he had. Stroke length will change the average piston speed nor way or the other. Rod length will change peak piston speeds and where that occurs as well as dwell.

 

Oh my goodness haha


My brother really wants an EG with a D series, naturally aspirated too. I honestly don't know why, I've presented him with every engine swap possible lol, but I do really like the idea anyway. So this thread will come in real handy when we start building, coming from a D series perspective

 

Sorry meant acceleration and deceleration based on the changes in dwell.

But now that I haven't even looked at any of this for quite a few days, and I haven't done any of the math. Maybe it's completely proportional and where it shortens dwell and is inversely proportional to where it adds dwell from the rod length change.

So maybe it didn't actually increase or decrease the maximum acceleration/deceleration the piston sees.... I really don't know. I do know adding the rpm will affect the max force the piston sees as accel/decel is a formula of speed (velocity) squared.

 

Finally sat down and started crunching some numbers. Noticed on the excel sheet linked by Victory Library two things. One Excel requires radians not degrees when doing the trig calculations. Second is the author of the Excel sheet multiplied by .6% not .3% like was quoted in the article and with a little digging the V/P numbers in the article are double what they should be because the Excel sheet was used on the article examples.

Being the V/P index is supposed to be a rough equivalent of the torque in foot-pounds at low running speeds (low to cranking rpm), I could not see my little 1.5 liter putting out over 100 ft-lbs at low speeds. Stock peak torque is like 98 ft-lbs at 5000 rpm. So after I made that correction the V/P index numbers I was seeing seemed more like where they should be using the mentioned .3%.

So lets define all the labels for the following table.
TVN=Total Volume Nominal. V/P=Volume/Pressure Index. CP=Cranking Pressure Absolute.
GP=Guage Pressure. CRe=Compression Ratio Effective. TVE=Total Volume Effective.

The farthest left column is the setup, the middle has the quench based off of head gasket and piston to deck height from zealautowerks, as well as it contains the TVN. Then the results of all the main calculations for each of the cams (fictional and real).

			BC-3/4					BC-3/4 (43.5°)		63441Y (44°)	63442Y (47.5°)	63443Y (49.5°)
B7 Rod	quench	V/P	46.89710219		Z6 Rod	quench	V/P	61.12886357		60.79914736	58.41514061	56.99652526
PM3 Pstn	0.050	CP	190.5098644		PMS Pstn	0.057	CP	248.5573466		247.8584213	242.7523171	239.6685827
B7 Head	TVN	GP	175.8098644		Y8 Head	TVN	GP	233.8573466		233.1584213	228.0523171	224.9685827
0.048 HG	102.1285856	CRe	8.456035113		0.027 HG	99.70370315	CRe	10.55417743		10.52944031	10.34836427	10.23869983
		TVE	93.06065792				TVE	90.55856917		90.34631592	88.79261954	87.85165992
			BC-3/4					BC-3/4		63441Y	63442Y	63443Y
B7 Rod	quench	V/P	49.60667537		Z6 Rod	quench	V/P	50.59898056		50.32859421	48.37332615	47.20962292
PM3 Pstn	0.029	CP	201.51695		P08 Pstn	0.041	CP	205.7415697		205.1733691	201.0221475	198.5149685
B7 Head	TVN	GP	186.81695		Y8 Head	TVN	GP	191.0415697		190.4733691	186.3221475	183.8149685
0.027 HG	101.5613054	CRe	8.861254412		0.027 HG	101.3504376	CRe	9.01579293		8.995038904	8.843119174	8.751112567
		TVE	92.49337774				TVE	92.2053036		91.99305036	90.43935398	89.49839436
			BC-3/4					BC-3/4		63441Y	63442Y	63443Y
Z6 Rod	quench	V/P	64.96261265		B7 Rod	quench	V/P	57.01351025		56.70941558	54.50976739	53.20010561
PMS Pstn	0.040	CP	264.1458336		PM3 Pstn	0.029	CP	231.6056984		230.9636657	226.2718049	223.4370706
Y8 Head	TVN	GP	249.4458336		Y8 Head	TVN	GP	216.9056984		216.2636657	211.5718049	208.7370706
0.010 HG	99.23762876	CRe	11.10295787		0.027 HG	100.2906891	CRe	9.950844085		9.927851541	9.759500456	9.657504333
		TVE	90.09249478				TVE	91.22276144		91.011981	89.46864952	88.53361649

So the left columns is basically a fictitious setup if we put the Brian Crower 3/4 race cam (BC-3/4) into the stock D15B7 engine with stock head gasket. This would mean a custom non vtec B7 cam that had the same Intake Valve Closing (IVC) timing.

The next entry in that set of columns is the same setup but with the Felpro D16Y8 head gasket.

And the third entry is the actual Honda Parts scenario I've been considering but with a .010 Head Gasket to get the optimum quench which I've read is between .035" and .040".

At first it really didn't occur to me how this formula was better the Effective Compresion Ratio but then I realized, this formula will take into consideration elevation changes and if you want air temp changes can be factored in. CRe on the other hand only looks at IVC.

I think ideally, the P08 piston would probably net the best power overall as the dish provides extra volume and allow the better flame front over the domed piston. The cost will be low end torque and power as the compression ratio drops a fair amount.

I'm sure there is other clues in this mix here, and this only represents the VTEC lobe.

I can do up the non vtec lobe on the Crower cams as the duration is there with the LSA so I've already deciphered the IVC event for those 3 cams on the primary/secondary (non vtec) lobes. The BC cam doesn't provide the LSA or Lobe Center Line Angle to decipher them and the cam card timing I believe is for the vtec lobe specifically.

I would also like the stock Y8 IVC numbers for both vtec and non vtec as then a full comparison could be done.

The other thing about this is it doesn't really show what the effect of the lift will do, it only looks at cam timing itself, not the lift height.

If anyone can provide any deeper reading into these figures I've presented, please do.

Here is the worksheet I used to build the above table:

SE = (S ÷ 2) + R + ((S ÷ 2) × cosA) - SQRT ((R²) - ((S ÷ 2) × sinA)²)
V/P = VE × CP × N × .3%

Bore	Stroke	Stroke-e	Rod	CI conv.
75	84.5	76.01958503	137	0.061023744
2.9527575	3.32677345	2.992898664	5.3937037
CRn	IVC-ABDC	NC	AP	CC conv
12.23	43.5	4	14.7	16.387064
VN	TVN	CRe
22.78083751	99.23762876	11.10295787
VC	TVE	CP
2.02856968	90.09249478	264.1458336
VE		GP
20.49455401		249.4458336
	V/P
	64.96261265

Everything is in Cubic Inches so if you wish to see it in Cubic Centimeters you can just multiply it by 16.387064

 

Great work! Glad you found that problem with the VL excel sheet

 

I wish I knew what is meant by 7000 rpm rules but I unfortunately, I don't.

That is right in line with all the information I've been seeing. The longer rod I've read is for longevity. Less angle allowing less wear and tear.

I haven't seen it say out right that it's at the cost of power but when all the hot rod magazines are talking about stroking a motor by reducing rod length and adding a larger stroke crank..... That would seem like it gives more power but increase wear significantly.

It seems that power and rod length or on opposite sides of the same stick. But that could be me just reading too much into it.

The reason why I looking for longer rod situation is more for longevity as I also want to increase the rpm the motor will sees. Stock it limits at 6800 and I was thinking it would be cool if I could take it to 8000 rpm.

---------------------------------------------------

Thank you everyone who has been watching me fumble my way around. I understand and don't blame you if you have had a chuckle or two at my expense. My brain becomes dysfunctional at times and will think 0.050" is 50/10000 not 50/1000 like it actually is. I do eventually find my mistakes and correct them once I realize there is a mistake.

Anyways, I have a crap D16Y8 head that I think I might put back together enough to slap a degree wheel on the cam gear and then play the game to see what angle the cam has 0.050" lift and then also what angle the lobe peaks at, and then maybe carry on and see where the exhaust peaks at so to document the LSA. And maybe even do the 0.050" on the exhaust.

Then I'll have base numbers for the stock head setup to compare with the after market cams.

Now I thought for sure I saw someone say something about flame front is perhaps just as important or possibly more important than compression ratio. This was in reference to the domed pistons. I've scrolled back (maybe not far enough) and can't seem to find it.

None the less, I was trying to think about that aspect and it seems there is no easy way for some lackey like me to make heads or tails of it without first getting into deep study of heavier mathematics and physics.

I did come across a pretty solid post about combustion in the chamber. Unfortunately the link is bookmarked at work so I will have to come back and edit the link in.

Here is the great post by Ranger Mike talking about Combustion:
https://www.physicsforums.com/thread.../#post-2461678

I really don't think there is an easy way to demonstrate or figure out what the different piston designs will do. I mean if anyone knows a way to put that onto paper to compare piston design setups, that would be phenomenal!

 

If you do, I would suggest doing up the D16Z6 really. The after market support is still there for it over any of the other D series. Also it's the strongest bottom end of all the D's.

I'm thinking after this I'd like to take the D15B 3 stage head and mate it to the Z6 bottom with a turbo and Hondata 300 tune. But I'm not ready to learn about turbo's yet, I'm still learning regular build stuffs.

This is still a high priority if it's even possible without a cray supercomputer.

 

By the looks of things, this not a simple thing to tackle or answer.

I found this really interesting paper where flow was analysed between two pent roof pistons. As it is, the pms piston seems to be considered as a pent roof piston with it's dome.

The paper:
http://www.engineeringletters.com/is...EL_17_3_08.pdf

Based off the paper, it looks like if the valve reliefs (pms only seems to have one set) were deepened a touch it could potentially create an offset "cavity" which might be of interest.

Just not sure if having the cavity on the intake side (I'm guessing the valve reliefs are for the intake valves on the PMS piston) will give the same increased turbulence results.

I'm sure the extra draw of the offset cavity will help regardless over an even/symmetrical design.

On another note, I measured one of the D16Z6 IM runner lengths with clay (#3) and found the length to the bell of the runner to be 11 inches not 12 like I found documented elsewhere. I think I may redo the measurement and also measure #4 as that runner is a little curvier than #3 and #2 and see if I get the same results.

I'm wondering if I should just keep posting forward in this mess of a thread or if I should update the first post specifications table to include all additional information I find as I go.

I sort of think after this journey is near complete a rewrite should be done in a new thread/post so that it's all in one spot and in a neat and orderly fashion, something this thread is not.

I dunno.