WeingartnerRacing wrote: ↑Mon Oct 22, 2018 10:13 am
You want as much lift as you can using the duration and lsa you need.(valve events). I have never seen more valve lift make less power. I would do a 234/246@0.050 106lsa. If you want it to be tamer idle then 108 lsa.
Thanks Eric for the reply. Still teaching?
WOW! A 12 degree split in duration, ok.
What about the other end of the lsa? What if it was on a 112 lsa? Would that make it tamer?
Yeah, it would tame it down, but it would throw a couple valve events out of what I would consider favorable for that build. I think Erics cam choice would run good. I'd be close, but id probably have a little shorter intake lobe and a 108-110 lsa.
Ignore the garbage of averaging a flowbench curve to pick a cam or ratio.
Your thinking the cam should build cylinder pressure.
I have a Luanti 280/288 and 226/234 @ .050 for .530/.530 on a 112 lsa sitting on the shelf I could use. I could throw some 1.6 rockers on there for additional lift. This would be cheap, since I already have this cam. Opinions?
What about the other end of the lsa? What if it was on a 112 lsa? Would that make it tamer?
Yeah, it would tame it down, but it would throw a couple valve events out of what I would consider favorable for that build. I think Erics cam choice would run good. I'd be close, but id probably have a little shorter intake lobe and a 108-110 lsa.
Ignore the garbage of averaging a flowbench curve to pick a cam or ratio.
Your thinking the cam should build cylinder pressure.
I have a Luanti 280/288 and 226/234 @ .050 for .530/.530 on a 112 lsa sitting on the shelf I could use. I could throw some 1.6 rockers on there for additional lift. This would be cheap, since I already have this cam. Opinions?
I don't hate that cam. I think it would run very well. If you got enough spring etc on it, run the 1.6's
CGT wrote: ↑Mon Oct 22, 2018 10:34 am
Yeah, it would tame it down, but it would throw a couple valve events out of what I would consider favorable for that build. I think Erics cam choice would run good. I'd be close, but id probably have a little shorter intake lobe and a 108-110 lsa.
Ignore the garbage of averaging a flowbench curve to pick a cam or ratio.
Your thinking the cam should build cylinder pressure.
I have a Luanti 280/288 and 226/234 @ .050 for .530/.530 on a 112 lsa sitting on the shelf I could use. I could throw some 1.6 rockers on there for additional lift. This would be cheap, since I already have this cam. Opinions?
I don't hate that cam. I think it would run very well. If you got enough spring etc on it, run the 1.6's
I could get whatever spring I would need for the additional lift. I might just use it and save me a few hundred dollars. Its so hard to sell cams on classifieds even if they have not been used.
tcb3274, looks like i am your question answerer, LOL. Cylinder head port flow ratio calculation = Exhaust port flow divided by the intake port flow (example) = 203 CFM exhaust flow divided by 290 CFM intake port flow = 203 divided by 290 = 0.7 = .70 = 70% . Exhaust port flows 70 % of the intake port. I have heard it stated that engines operating in a narrow high RPM band such as all out drag racing like a HIGHER ratio, and engines that would say be raced on a road course operating over a wider RPM range would like a lower percentage (ratio) ???? Mark H.
Do it the right way and add up your intake flow numbers up to .550"lift.
This comes to 1323 cfm.
Now do the same with the Exh numbers and be sure to use the flow number at .100" lift.
If you came up with for example a total Exh flow number of 926 cfm then you would have a overall 70% Exh to Intake ratio.
Most times with the compression ratio your looking you want a 75% ratio and a decent header with pick you up that needed 5 % atleast in terms of lifts above .400".
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
WeingartnerRacing wrote: ↑Mon Oct 22, 2018 10:13 am
You want as much lift as you can using the duration and lsa you need.(valve events). I have never seen more valve lift make less power. I would do a 234/246@0.050 106lsa. If you want it to be tamer idle then 108 lsa.
Thanks Eric for the reply. Still teaching?
WOW! A 12 degree split in duration, ok.
What about the other end of the lsa? What if it was on a 112 lsa? Would that make it tamer?
I left teaching this year.
The longer duration on exhaust helps carry the peak longer when your exhaust port is just good but not great.
The 112lsa would make it very tame at idle bit you would give up torque and horsepower especially down low. On low compression motors I try to get the cam to build cylinder pressure. The valve events can be adjusted in some ways to give you similar numbers. Ie smaller duration wider lsa.
For the record no matter how good a cam guy is after you get data from one motor run with the cam if you’re smart you can figure a better camshaft.
Eric Weingartner
Weingartner Racing LLC
918-520-3480
www.wengines.com
mag2555 wrote: ↑Mon Oct 22, 2018 6:38 am
What is the overall Intake to Exh ratio if you add up and then average those numbers up to let's say .550" lift?
This needs to be concidered also!
If you come up with a number of 70% then your headers will make up the added 3 to 5% if there at least 1 5/8" ID , but not over 1 3/4".
Yanking 280 cfm thru certain Intake Manifolds like the ones you should be looking at for the best average power from 3k to 5800 may be needing some rework!
Intake flow wise you will need to average 255 cfm@28" to make a solid 500 hp, so it looks like a valve lift of .525" will get you there.
What math are you talking about to average the intake and exhaust ratio? I don't follow your first three sentences.
Go to the local library and look in the FICTION section for volume 1 of " How to FlowZ spec the perfect cam "
I think the book should be in the comedy section, but I didn't organize the library.
mag2555 wrote: ↑Mon Oct 22, 2018 6:38 am
What is the overall Intake to Exh ratio if you add up and then average those numbers up to let's say .550" lift?
This needs to be concidered also!
If you come up with a number of 70% then your headers will make up the added 3 to 5% if there at least 1 5/8" ID , but not over 1 3/4".
Yanking 280 cfm thru certain Intake Manifolds like the ones you should be looking at for the best average power from 3k to 5800 may be needing some rework!
Intake flow wise you will need to average 255 cfm@28" to make a solid 500 hp, so it looks like a valve lift of .525" will get you there.
What math are you talking about to average the intake and exhaust ratio? I don't follow your first three sentences.
Go to the local library and look in the FICTION section for volume 1 of " How to FlowZ spec the perfect cam "
I think the book should be in the comedy section, but I didn't organize the library.
swampbuggy wrote: ↑Mon Oct 22, 2018 12:06 pm
tcb3274, looks like i am your question answerer, LOL. Cylinder head port flow ratio calculation = Exhaust port flow divided by the intake port flow (example) = 203 CFM exhaust flow divided by 290 CFM intake port flow = 203 divided by 290 = 0.7 = .70 = 70% . Exhaust port flows 70 % of the intake port. I have heard it stated that engines operating in a narrow high RPM band such as all out drag racing like a HIGHER ratio, and engines that would say be raced on a road course operating over a wider RPM range would like a lower percentage (ratio) ???? Mark H.
Ok, Im confused.
exhaust divided by intake =?
Can I stop at .500 lift? I don't have a exhaust flow number for .550.
WeingartnerRacing wrote: ↑Mon Oct 22, 2018 10:13 am
You want as much lift as you can using the duration and lsa you need.(valve events). I have never seen more valve lift make less power. I would do a 234/246@0.050 106lsa. If you want it to be tamer idle then 108 lsa.
Thanks Eric for the reply. Still teaching?
WOW! A 12 degree split in duration, ok.
What about the other end of the lsa? What if it was on a 112 lsa? Would that make it tamer?
I left teaching this year.
The longer duration on exhaust helps carry the peak longer when your exhaust port is just good but not great.
The 112lsa would make it very tame at idle bit you would give up torque and horsepower especially down low. On low compression motors I try to get the cam to build cylinder pressure. The valve events can be adjusted in some ways to give you similar numbers. Ie smaller duration wider lsa.
For the record no matter how good a cam guy is after you get data from one motor run with the cam if you’re smart you can figure a better camshaft.
I currently in between teaching jobs. It gets harder to stay in with all the crap that continue to put out. Unfortunately, the education is system is dominated by one side and that makes it harder as well.
I follow what you saying on carrying the peak longer.
I follow what your saying on cylinder pressure and makes good sense.
What cranking compression should I be looking at? 195 psi to 210 psi seem safe to me on 93 octane here in Florida.
What is your impression of the cam I already have? A 280/288 and 226/234 @ .050 with .530/.530 on a 112 lsa. It is just sitting there.
Probably a cam from Straub or Cam King would be better.
Last edited by tcb3274 on Mon Oct 22, 2018 1:49 pm, edited 1 time in total.
tcb3274 wrote: ↑Sat Oct 20, 2018 9:03 pm
Here are the flow numbers for a set of Trick Flow 195 heads that have been ported by Eric Weingartner. How much lift should I be looking for in a camshaft?
These flow numbers look like the first step to a potent build.
Give me the head port volume and the engines CID, CR RR, rod length, peak power rpm required, Vacuum required what type of cam you want (flat -solid -hyd -roller) And I will run some numbers for you cam wise that will make the most of what will probably be a set of great heads. Also give you the power and torque output to within +/- 3%.
DV
You don't take into consideration min CSA or exhaust flow? I would have thought them important factors.
Yes you are right but I am going to tell him what he needs and we will work from there.
DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.
I hate any recommendations for cam based on exhaust to intake ratio. That is the biggest bunch of bullshit. You make the ratio go way high if the intake port sucks. You give the engine what it needs.
Eric Weingartner
Weingartner Racing LLC
918-520-3480
www.wengines.com
steve cowan wrote: ↑Sat Oct 20, 2018 10:20 pm
Did Eric port these heads for you??
If so probably best to ask for his recommendation on a cam for your combination,
If not then you would be best to give all the details of engine, trans, converter, rear gear etc etc
Can't pick a cam by flow numbers alone
Steve, yes he did port them for me.
I will place a call into him.
Details of the engine. 383, rpm intake, Holley 3310, 1 3/4" headers, 4 speed, 4:10 gear
230 at .050. Intake. .56-.58” lift. Hyd roller. Thats a nice street powerband to 6500
