Gaining CFM/WHP at the Valves

[Joey GT-R]

I've bought some cams for my project and before the install I got to thinking of how I could maximize the power to the head. I understand that oversizing the valve port will obviously allow more air to flow in but I'm wondering as far as my choice for parts as to what does it the best. In my readings I've understood that upgraded valves can net a .5-2 CFM gain. For every 2 CFM gained, 1 WHP is gained. Is that correct? With the PnP I'm having done, the estimated gain is about 15-25 CFM, so I'm imagining that's roughly about a 7-12 WHP increase? Is that reallistic? So with the valves am I looking at an additional 8 WHP roughly?

[Jarrett]

I don't like proportionate comparisons like the one you gave. It's the same as saying that dropping 100lbs on a car is good for x number of seconds off in the 1/4-mile.

When you say valve ports are you talking about the valve seats or the intake ports? I'm assuming seats since you're talking about oversized valves. There are both +.5 and +1mm oversized valves for the F22A. Both of them will yield more than a .5-2CFM gain. Neither should be coupled with a bone stock head.

When working over a cylinder head your primary objective is to increase flow. In tandem with that is a consideration for retaining velocity. If you increase flow too much then you've shot velocity and will no longer make efficient power, especially in the lower RPM range. That's why I don't like the CFM to HP relationship you proposed.

In short, an oversized valve setup (with a multi-angle valve job) will yield some performance gains. But only when it's coupled with headwork that can compliment it. A camshaft upgrade (I know you have one) and a boost in compression would be beneficial here as well. Also, you're not going to see much, if any, improvement in the lower RPM ranges. Increasing the flow of a head has more to do with allowing it to breath better on the top end.

[Joey GT-R]

I wasn't using the proportion as an absolute, but in my research that was the "status quo" of my findings.

I was meaning the valve seats, the term was eluding me at the time of my post though. I have an H22A, so there are +.5, +1, and a +2(Intake) available. I'm not sure if the +2mm for the intake is over doing it, so I'll probably stay at +1 all around. Would you say there is still more than 2 CFM gain there? I wasn't just going to install the valves by themselves, guides, seals, springs, and retainers would be added as well.

So was I correct in my assumption that valves gain CFM on their own in addition to the PnP, or just in collaboration with the PnP?

I'm actually kind of glad you said the proportion was wrong. I was hoping for around a 25 whp gain with the amount of coin I'm dropping.

[Jarrett]

Alright, this is VERY crude, but I did a little bit of easy math to show the relationship between flow rate and valve size. This is by no means scientific but is meant to show that a +1mm valve increase can yield more than 2CFM of flow. Especially when coupled with a multi-angle valve job.

An H22A intake port flows roughly 272CFM in stock form. Per valve that's ~136CFM.
It has a 35mm intake valve of which the surface area is 96.211mm^2

If you enlarge the intake valve by 1mm to 36mm then you have a new surface area of 1017.876mm^2.

If you use cross multiplication and division then you can determine a theoretical flow rate based off of the assumption that the relationship is directly proportional(it isn't). That would be ~144CFM. That's an increase of 8CFM per valve and 16 per cylinder for a total of 288CFM. Again, this is theoretical but it's to show that you're looking at more than just 2CFM. That's a good thing though.

[wed3k]

ive seen oversized valves do nothing in flow...it depending on how you accomodate to an OS valve.

enlarge throat
unshroud the seat area in the chamber
valve job
back cut the valve is necessary

a lot of exhaust seats are already sunk which does nothing for low lift numbers. id recommend putting in new seats.

[MortsAccord]

Do the math for 132 CI 90% VE @ 7000 RPM

(132 x 7000 ) / 3456 = 267 CFM(this would presume 100% VE)

267 x .95(Volumetric Efficiency) = 253 CFM
267 x .9(Volumetric Efficiency) = 240 CFM

divide CFM by 8 to find per valve CFM
100% ve 33.3 CFM per valve
95% ve 31.6 CFM per valve
90% ve 30 CFM per valve

If the relationship between intake track and valves stays the same then the increase in flow should be just over the exact % of increased surface area. This is because of increased valve size and reduced velovity of the air being sucked into the combustion chamber, both characteristics that increase flow.


the following calculations were done here: http://www.csgnetwork.com/surfareacalc.html using a cyln with a height of 0
surface area of a 35mm valve is 1924
surface area of a 35mm valve is 2035

it ends up being about a 6%(just under really) increase in surface area. So in theory you should flow about 5-6% more air

This will get you:


100% ve 33.3 CFM per valve +6% = 37.4 per valve or 299CFM total
95% ve 31.6 CFM per valve +6% = 33.5 per valve or 268CFM total
90% ve 30 CFM per valve +6% = 31.8 per valve or 254CFM total

It should be noted that I did not use any perfect numbers and rounded up/down on some nuymbers to simplify things a bit. If you want more dedicated numbers then DIY!

Almost a 6% flow bump on the books but I'd call it a 5% more flow on intake, but if only the intake is done it would probably be closer to 4%.

[Joey GT-R]

My head hurts....but I think I can say overall that my question was answered. wed3k I've had numerous other "naysayers" say that the valve increase can sometimes be seen as useless, or overkill for my goals (400-500whp). So what if I kept the sizes the same? What if I didn't even do the port? Other than increased strength, and supposedly lighter materials for weight savings is there any CFM still gained? I'm going to wager that at that point there's probably my 2CFM per valve.



P.S. I love when I can post about "super complicated stuff" over a week ago and come back to only well thought out posts......No noobs allowed, Lol.

[MortsAccord]

400hp? I presume you are going turbo because N/a will never reach that hp potential.

Focus on exhast evacuation. I cannot stress this enough. So much of your power will be gobbled up by the motor trying to push the exhaust out its mind boggling.

This is seen in any forced induction, not just turbochargers. The most realized applications aside from turbo exhaust mods are nitrous engines with extensive modifications to the exhaust side so to free up hp.

Remember when you have 2 engines making say 200 WHP one could be doing so with ease while the other is working its guts out because the exhaust system is just choking the life out of the engine. litterally.

Theres a honda tuning mag article with a red accord in it, its got a turbocharged H22 with dual waste gates. That is a prime example of how to deal with excessive exhaust and the ONLY thing i can say negative about his manifold and exhaust system is teh waste gates arent made with a 45-60 degree flange from the exhaust manifolds tubes. they are at a 90* bend.

Check this site out:

http://mysite.verizon.net/vzezeqah/ (formerly grapeaperacing.com) Read the turbocharging tech articles and all the other ones too. Theres REAL information there that is worth every second of reading.

[dj_ender]

400hp? I presume you are going turbo because N/a will never reach that hp potential.

O rly?

[Jarrett]

I agree 100% with the concept of exhaust scavenging. The cam in the Camaro is a Torquer v.2 from Texas Speed. The specs are 232/234 .595"/.598". When it was purchased 4-5 years ago that was pretty odd. Now it seem with LSX cams that it's the norm and the specs are much more wild than they used to be.

[MortsAccord]

F bisi >.> Why is everyone so on his cock-n-balls? woo hoo(like from "legend of awesome" flash clip)

Theres a enormous difference between the build he uses for the insight and a reliable engine that will haul the mail for miles and miles. its like comparing my weed eater engine to a nitro funny car build.


He also stated 400-500WHP WHEEL HP? N/a? from a 2.2? Yea right, no one on here would be asking about simple questions if they had the bank to throw down on a build to that extreme

[dj_ender]

F bisi >.> Why is everyone so on his cock-n-balls? woo hoo(like from "legend of awesome" flash clip)

Theres a enormous difference between the build he uses for the insight and a reliable engine that will haul the mail for miles and miles.


He also stated 400-500WHP WHEEL HP? N/a? from a 2.2? Yea right, no one on here would be asking about simple questions if they had the bank to throw down on a build to that extreme

I'm not on his cock and balls, just correcting your incorrect statement, plain and simple.

[Joey GT-R]

I won't say that I'm an expert but I will say that I feel versed in the subject of scavenging. However that is the downfall to our chassis. There is no primary solution for an exhaust manifold in our car, if you want to keep A/C and P/S.

[MortsAccord]

he made that with brake hp, not with his drag wheels on. 9.2-9.3k rpms?

Yea you can get silly power from revving to the moon on almost any engine though, if your willing to completely throw away all forms of reliability away.

http://thefirstgensite.com/code/maxrpm.htm

Input 3.74015748 which is 95mm converted to inches. calculate for racing componets (5000 fee per minuite =25.4 meters per second) hes revving it out to ONLY 29.45 meters per second. - top fuel funny car speeds where shit just randomly frags apart and there is no guarentee your engine will live 10 seconds ot 20 minuites at that power output.

Hes a salesman I'll give him that.

[dj_ender]

he made that with brake hp, not with his drag wheels on. 9.2-9.3k rpms?

Yea you can get silly power from revving to the moon on almost any engine though, if your willing to completely throw away all forms of reliability away.

http://thefirstgensite.com/code/maxrpm.htm

Input 3.74015748 which is 95mm converted to inches. calculate for racing componets (5000 fee per minuite =25.4 meters per second) hes revving it out to ONLY 29.45 meters per second. - top fuel funny car speeds where shit just randomly frags apart and there is no guarentee your engine will live 10 seconds ot 20 minuites at that power output.

Hes a salesman I'll give him that.

I'm not arguing with your math or logic, but you said it wasn't attainable. I posted a video that it is. So what if it's a full out race car? It's possible, even if its one pass or 20.