Denny
Canned Monster
Eth is good! Well, not as bad.
That's actually the SCR I used, totally missed the advanced settings... I have my cam specs from Dover as well despite it being a RevPro cam.DCR should be the #1 most important calculation for any engine build.
Here's a SCR calculator with DCR in advance mode.
Compression Ratio Calculator (Static and Dynamic)
The compression ratio calculator finds both the static and the dynamic compression ratio of your combustion engine.www.omnicalculator.com
Heres a cam degree calculator.
It'll show you how 2 cams with very similar specs will act totally different in the same engine.
IVC is the most important out of the 4 valve events, but retarding or advancing a cam will change ALL 4 events.
NRRacing makes some very strong cams, they have ALOT of advance built in. That's no big secret, auto cam makers have been doing it for yrs and yrs. It's a crutch, used when the builder picked too big of a cam.
There is absolutely nothing wrong with either of those 220* NRRacing cams. They are both great for moving weight, fast. We call the 0211 cam the "Fat Boyz cam". It works exactly the way it was designed for.
I'd rather use a smaller single pattern cam, with less LSA and no advance or retard built in the cam.
Isky is the only cam grinder to put the clone style cams on a 104* LSA.
Compare the isky custom .260"/ 220*/ 104 lsa cam with the NRRacing 220* and you can see how the 4 valve events are being changed.
Isky cams are single pattern cams.The thing I don’t understand about the way small engine cams advertises their custom cams is the LSA.
It says 104 LSA for max torque.
108 best all around
110 for top end.
This would make sense to me if it were ICL, but it says LSA.
I’ve thought that less LSA would increase overlap. I thought more overlap would be better for top end, not torque.
in my mind, more overlap would bleed off compression at low rpm. The overlap would be useful at higher RPM when scavenging helps.
I’ve tried to understand this. I’ve had many agree with me and thought it was a typo on the Isky site. It doesn’t give you a choice for ICL with their custom cams, and Centerline and duration would give you intake closing.
The only 208's I have pulled the head off of was 20-22cc small valve heads, but they were old used worn out engines. Idk if they had the factory head on em or not.With the 76° intake closing I get 8.6 dynamic assuming the head is 18cc like I believe it to be, since all I did was swap the dished piston for a flattop it follows with the factory spec of 8.5:1 that the head IS IN FACT 18cc.
If I can get a 14cc head to toss on it, that looks to jump the CR all the way up to 10.8:1
Cam Specs
Intake
Open 30 Close 76
Lift 234
CL 112
Duration @ 050 > 220
Exhaust
Open 67 close 42
Lift 240
CL 105
Duration @ 050 > 223
LCT Husqvarna 208 Winter SpecThe only 208's I have pulled the head off of was 20-22cc small valve heads, but they were old used worn out engines. Idk if they had the factory head on em or not.
My small genie is a 208, but I be damned if I'm pulling that head off for you to have a look see, .
I've never had the chance to take a NEW 208 apart. They on log splitters, water pumps and genies around here.
What numbers are you inputting in the CR calculator???
11.6 is high for jus adding a long rod and ft piston.
Don't believe that stock 8.5:1 crap. Only stock engines I seen that was 8.5+ was the 224 pred and ducar.
The 196 and 212 is only 7.7-8.3, that depends on the head and gasket.
Here you say 11.5, sorry my bad on the 11.6.I saw mention of a compression calculator somewhere and went looking.
Assuming 100% accuracy of the calculator and my inputs, it shows my 208 has a CR of 11.5:1, the factory spec sheet says 8.5:1 having put a flat top piston under it's 18cc head, in the off chance it's a 20cc head I'm still getting 10.6:1.
The real irony is if I put 93 through it, it runs a lot hotter but not really any better.
I can't seem to find Ethanol free gas like I could up in NY (I could get 90/0 locally and it ran great) So I have half the mind to set up a phase separation table and start pulling that sh¡t out before tossing in something like Heet101 or Stabil to recover some of the lost potency of the process.
Ah Thank you.Isky cams are single pattern cams.
Straight up, is a cam with 104* lsa, will be 104* icl and 104* ecl.
108* lsa, is 108* icl and 108* ecl.
110* lsa is 110 icl, 110 ecl.
It's easier if you look at automotive cams, they will give you more specs.
Advertised duration (could be at .004" tappet lift or .006", depends on how the manufacturer is measuring it).
Subtract the duration .050" # from the advertised #, the cam with the smaller # will be a more aggressive, faster ramp camshaft.
ECCarbs has got the best cam cards for these clone style cams. They are very aggressive, fast ramped cams. They are not playing games when it comes to springs and head work.
I DONT recommend ANY Tennessee Thunderstick for a new builder.
For some reason, who knows why, some so called wanna be clone cam makers wanna keep things secret, , I quess they try to hide the REAL truth about how and when power is made.
My best guess is, so they can sell as many bs, useless, under powered, overpriced, pos cams they can until.......people wise up and start buying cams made for men.
Ed Iskederian
Harvey Crane
Sig Erson
Know more about cams then I will ever understand.
Davis Vizard knows a thing or 2 about how those lil bump sticks work too.
Look em up. You can only learn..... as much as you are willing to learn
Overlap is not a bad thing, but too much will kill power brakes.
I don't know too many karts or mini bike running power brakes. , but who knows.
I dont wanna get into the vacuum deal, as some body mentioned earlier, but they might be jus a tad bit MORE involved then jus "lack of pressure".
It might jus be about what's going on inside the combustion chamber causing that lack of pressure, when it should cause that lack of pressure, where that pressure should be pushed.... at a certain time.
Maybe and jus a wild guess..... valve timing???
@bob58o
I seen that a yr or 2 back.
Seems like some guys were saying there was a mis quote in there somewheres, I don't remember what it was. I'm sure it's fixed by now.
Nothing jumped out at me while I was re reading it.
It's a good read and alot of useful info.
Static comp, my bad tooHere you say 11.5, sorry my bad on the 11.6.
Static comp, my bad too
Yep
I understand.
Those numbers become a jumbled mess....if you look at em too long.