How much lift for these flow numbers

[tcb3274]

Im not sure I understand what head port volume is.

I would guess the intake port CC, for example 180, 195, 215 etc

The head is a Dart Conquest 200.

[steve316]

pick duration for application; pick as much lift as you can to maintain endurance for for rocker arm ratio and peak rpm.

[Steve K]

I ran a Bullet 254 256@ 50, 114 lsa hyd roller in my old 383. With AFR210's and tunnel ram it dyno'd at 535 hp and 500 tq. Had about 9.0:1 compression. I was very streetable, fun to drive and surprisingly fuel efficient with a TKO600. I like big cams in my engines and with a stick and no vacuum requirements the door us pretty wide open. I did a 383 with pretty much the same set up as yours with maybe a little less port flow (ported Sportsman ll heads) and made 465hp/500tq with a 235/242 hyd roller.

[swampbuggy]

tcb3274.....to answer your question, port volume (the port most discussed is the intake) is the number of c.c.'s (cubic centimeters) of liquid usually mineral spirits that it takes to fill the entire port. Lightly grease the valve where it seats on the seat, light springs are all that is needed. Position the head with the port opening (where intake gasket seals) upward. Place a small piece of plexiglass with a funnel shaped hole on port opening slightly greased. fill port to bottom of hole with calibrated device (burette) to determine port volume ( number of c.c.'s ). Mark H.
BTW,( minimum cross sectional area) also is a factor sometimes.

[John Wallace]

BTW,( minimum cross sectional area) also is a factor sometimes.

Especially when comparing heads that may have a longer/shorter total length than other heads.
One head with a small minimum cross sectional area but a longer port length could have the same cc's as one with a larger mcsa and shorter port length.
But the port speed would probably be different?

[steve316]

It is hard to get out of the mind set of comparing heads by volume. Cross-sectional area and minimum cross-sectional plays a lot larger roll than volume. they have a large effect on air speed. There are a lot of variables that determines what heads would work best.

[swampbuggy]

John and Steve, i agree with what you both said. The MCSA will only flow SO MUCH air and thats it. Mark H.

[cjperformance]

MCSA and flow is a better way to compare heads off of different platforms. Ie sb chev compared to say ford cleveland where the port lengths are different.
Flow and runner cc is great for comparing different heads from the same platform where port length is pretty much the same.
Personally i think mcsa needs to be included as its a great look at port efficiency.

[In-Tech]

I have never understood why port volume is even a context of a conversation. MCSA is the key factor in many many heads. Tapered intake manifolds along with tapered intake ports might be the only place a volume would matter and again, as stated in the good last few posts, change with length and taper.

[4vpc]

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?

.200 -141
.300 - 194
.350 - 216
.400 - 237
.450 - 255
.500 - 269
.550 - 280
.600 - 285
.650 - 288
.700 - 290

Thanks

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.

[mag2555]

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.

[tcb3274]

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.

The cam I have in mind has .530 lift, but if I rin 1.6 rockers it will be .577 lift.

[WeingartnerRacing]

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.

[tcb3274]

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?

[CGT]

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.