"Lopey" cams vs drivability
10-13-2016, 06:23 PM
#21
Burning Brakes
Your 227/239 114 cam has 5 degrees overlap which is why it is very nice to drive. When I was going to stay nitrous I had a 230/238 113 cam which was specd by Pat G with 8 degrees overlap, which was about the limit of a nicely driving cam from what i'd gathered.
And of course there are some people who can drive a cam with 30 degrees overlap and call it "street friendly"
And of course there are some people who can drive a cam with 30 degrees overlap and call it "street friendly"
10-13-2016, 06:48 PM
#22
Team Owner
Last edited by Unreal; 10-13-2016 at 06:48 PM.
10-13-2016, 07:08 PM
#23
What do you guys think it is about the overlap that causes the surging?
I know more overlap gives the engine that lumpy race car idle, and it's my understanding that more valve overlap also drops engine vacuum (at lower rpm). What else is it doing to mess with the fuel system?
.
I know more overlap gives the engine that lumpy race car idle, and it's my understanding that more valve overlap also drops engine vacuum (at lower rpm). What else is it doing to mess with the fuel system?
.
Last edited by dmk0210; 10-13-2016 at 07:14 PM.
10-13-2016, 07:50 PM
#24
Team Owner
Has nothing to do with fuel system.
Airflow dynamics, reversion, etc.
Airflow dynamics, reversion, etc.
The following users liked this post:
GreenHornet1 (06-15-2023)
10-13-2016, 08:01 PM
#25
What do you guys think it is about the overlap that causes the surging?
I know more overlap gives the engine that lumpy race car idle, and it's my understanding that more valve overlap also drops engine vacuum (at lower rpm). What else is it doing to mess with the fuel system?
.
I know more overlap gives the engine that lumpy race car idle, and it's my understanding that more valve overlap also drops engine vacuum (at lower rpm). What else is it doing to mess with the fuel system?
.
10-13-2016, 10:50 PM
#26
Burning Brakes
http://lmgtfy.com/?q=calculate+cam+overlap
(and yes, I may have deserved your answer)I had actually done this earlier and came up with an overlap of 3 degrees, not 5. So I was assuming there was some part I missed. Reading cam specs isn't in my wheelhouse at the moment and was just hoping for a quick answer from someone that I assumed did it on the fly.
10-14-2016, 08:32 AM
#27
Melting Slicks
I guess the first question is what I am doing with this thing. If you poop around town and just general driving keep the overlap low. If you race it a lot or can live with more overlap that is another story (some people can stomach it more than others). Like the guy said above people have 30 degrees overlap and call it street friendly. I have 23 degrees of overlap at .050 and I would go no more for what I am doing and my engine is a little larger at 454 (would I trade 10 degrees less overlap for 5hp the answer is yes 30hp maybe not). Other people can chime in here with what they have but I think for a street car 10 degrees (with a little race sound) is a start like the Katech torquer is like 12 degrees. I would keep the cam on the small side and do the magic work on the heads and make them flow better so the cam does not have to do all the work. I can not stress enough find a good tuner. You can have no overlap but if the guy does not know what he is doing, the car can drive like a car with 20 degrees of overlap.
10-14-2016, 12:59 PM
#30
positive overlap means that the valves have a moment where they are both open in between exhaust and intake stroke, since both valves are open some intake charge can slip out the exhaust or depending on back pressure can cause reversion. It's more complicated than that but basically that's what causes the issues with driveability. I'm sure someone can chime in more with the science behind it.
Thanks for the info
.
Last edited by dmk0210; 10-14-2016 at 02:12 PM.
10-17-2016, 03:31 PM
#31
Racer
IMHO, of course.
KW
Last edited by KW Baraka; 10-17-2016 at 03:34 PM.
10-18-2016, 08:23 AM
#32
Team Owner
Comp is the WORST place to get cam info. Talk to someone like BTR, Pat G or a LS cam expert. Comp spits out the stupidest cam recommendations I've ever seen.
10-18-2016, 11:30 AM
#33
Drifting
.050 Cam degreed at
210 Intake Duration
230 Exhaust Duration
116 Intake Centerline
120 Lobe Separation Angle
.330 Intake Lobe Lift
.594 Intake Valve Lift
.328 Exhaust Lobe Lift
.590 Exhaust Valve Lift
-20 degree of overlap
The following users liked this post:
Cherokee Nation (10-18-2016)
10-18-2016, 01:50 PM
#34
Team Owner
What about it? The specs are all there. Its a non-split 224 duration cam that is on the low side. What do you want to know?
10-18-2016, 11:47 PM
#35
Racer
01-31-2017, 12:50 AM
#38
Drifting
Member Since: Dec 2015
Location: Wes is gay :) California
Posts: 1,776
Received 59 Likes
on
56 Posts
Cam
Here's mine with a 110º LSA/25º overlap cam.
https://www.youtube.com/watch?v=Lkg_iWv_FFM
https://www.youtube.com/watch?v=UmVpugHSEnc
I've driven it in New York, Chicago, Las Vegas and San Francisco with it. It does surge a bit at 1500 RPM's but I can live with it.
https://www.youtube.com/watch?v=Lkg_iWv_FFM
https://www.youtube.com/watch?v=UmVpugHSEnc
I've driven it in New York, Chicago, Las Vegas and San Francisco with it. It does surge a bit at 1500 RPM's but I can live with it.
what cam is this ? The katech toquer 110?
