Brian Tooley Racing

iTrader: (13)

Astronomical VE? Anything more than 100% and your beyond atmospheric pressure, coupled with the fact that the piston is 1/3 of the way BACK up the bore before the intake valve gets close to being shut (lets say 240 @ .050 cam), and you have A LOT of pressure in the cylinder trying to push its way back out of the bore. If you have 30" of pressure in the cylinder (just over atmospheric), by the time the piston gets 1/3 of the way up the bore at the end of the intake cycle the pressure in the cylinder is going to rise to 45", half again where it was. At this point the piston is still rising up the bore and the intake valve is still open, but getting close to finally being shut, intake port reversion happens at this point. An equally flowing port with less cross section and a smaller valve will have higher velocity around the valve, fill the cylinder just as efficiently when the piston is going down, will pack the cylinder better when the piston is coming back up, and the smaller valve will act more like a check valve against intake port reversion.

Boost has no effect on intake port reversion, as a matter of fact, boosted air will ram better then N/A air simply because it's mass is greater, it will be less subject to changing directions due to this increased mass. Exhaust port valve does have a dramatic effect on blower engines, a bigger exhaust valve will usually make less power. It seems you have not delved too far into physics, an N/A engine naturally has 29.92" of mercury (roughly 14 lbs of boost) pressure on the intake port, the problem is the exhaust port has to push against that same amount of pressure. You have to rely on the efficiency of the exhaust side of the engine to scavenge the bad gas off the top of the piston. An engine with let's say 14 lbs of boost now has 28 lbs of pressure pushing air into the cylinder during overlap, but only 14 lbs of pressure on the exhaust port, it is during this overlap period that too much boost can be blown out of the exhaust port during overlap, making less power. You can also look at that pressure differential another way, we have all put our finger on a vacuum port on an engine that pulls 20" of vacuum at a idle and feel the suction, this is what the intake valve is feeling from the exhaust during overlap, except more, to the tune of 29" of vacuum.

The other thing about big valves is they "can" make more torque, simply due to helping scavenge exhaust gases during overlap, too much can hurt. Where the intake side of the engine acts like an infinite curve, whereas as you increase flow without increasing valve diameter or port cross section, your gains in power gets infinitely smaller and smaller, but an engine will NEVER make less power due to increased intake airflow. The exhaust port is like a bell curve, "proper" scavenging yields best power, but under scavenging yields less power and over scavenging yields less power. This is why one person can install a better header collector and gain power while another person can install the same collector and lose power. So the exhaust side of the engine becomes a "tuning" game, with cam duration, overlap, header diameter and valve diameter.

The luxury I have had is that I don't do a few heads a month, I do a few heads a day, or many heads a day. I receive LOTS of feedback, we have done LOTS of testing, many times I have had to change my theories to coincide with what were finding as we test. All of this testing was not done on Pro Stock engines running 9500 RPM, it was done on 6500 RPM street cars with mufflers, and I think there are stark differences between the two. You can not compare the pressures that are taking place during overlap to what a street car sees, or the pressures that are in the cylinder at the end of the intake cycle. When you have a street car with a 2.20 valve making power to 6500 RPM it is completely different from an engine with the same valve trying to make power to 8500 RPM or 9500 RPM, and you have to remember that Pro Stock Truck intake valves were not much bigger than 2.20"

I will restate what I said above, the ONLY reason I am touting the smaller valves is due to the fact that we are making power easier with smaller intake valves that flow more mid lift airflow, and I have back to back tested smaller exhaust valves that made more power. How else can you explain an LS6 head with 2.10 valves making 600 RWHP and the same basic combination with a LS7 head and 2.20 intake valves making 520 RWHP, do you think it is all exhaust gas reversion into the intake port during overlap? Cause if you do then you made the argument why a smaller intake valve is better.

2c5s

iTrader: (11)

Why is it I see a number of LS7 headed cars making close to 600 rwhp with stock port LS7 heads and small cams?

It's good to know that your smarter than the engineers at G.M.

Ryne @ CMS

iTrader: (10)

as a supporting vendor your really making youself look stupid by arguing your case in this matter, and pretty much hijacking a thread with some valuable information. i just think this is a bad move on your part......

Greg Good

Brian, I'm not going to waste my time reading your hammered out prose. You're trolling a man who has spent his own coin to engage in some interesting R&D. You say that you had these heads two years ago? And that you didn't get good results? Then you had your turn. Sit back and let others work. My honest opinion is that you don't have a good grasp on how air moves through an engine, judging by your rhetoric.

A 2.100" intake valve is about right for a 5.3 head running 9.90's (Edit: on a pump gas daily driver).

StingrayCrazy

iTrader: (5)

ThirdGenLS1

iTrader: (11)

meh i have no problem arguing as long as it doesnt bring a bitching match. Theres nothing wrong with stating each others opinions and bringing their ideas to the table.

edcmat-l1

iTrader: (10)

Thanks for keepin the thread alive, Brian.....lol
BTW over 10000 views!!!

Stang's Bane

iTrader: (22)

Very key part here. STOCK port. I have had quite a few conversations on this matter and from what I can gather, The stock ls7 port(and L92, for that matter) is so good that unless someone really knows their ****, porting it will f*** it up. True enough, flow numbers may increase, but H.P. will not.

What porting is needed is very little, as you can see from the WCCH head, Richard went after quality of flow, rather than quantity. The WCCH head is a great looking piece, great running piece, and should be reasonably priced. Can't wait to see some numbers out of it when it gets a manifold on top that will keep up(you hear that Kevin )

And on the manifold subject, that damn thing needs shorter runners like a ****. PeaK ~6K, not the best for H.P production, pretty damn spiffy for TQ, though.

Sorry for the Kevin, Just had to point that out.

You have a PM!

FRDnemesis

iTrader: (19)

I've learned more in the last couple weeks reading this post about cylinder head designs than I have in the past few years. Excellant stuff about L92/LS6/LS7 heads and the fantastic thing is that I'm down to crunch time on my purchase and this thread has helped more than if I had paid someone for the information.

Jeff

WKMCD

iTrader: (2)

I couldn't agree with you more. Richard did a very thoughtful job on these heads. I bet he and I have had 5 or 6 hours of long distance calls about them.

Don't worry about the hijack. At least your not a vendor/sponsor interjecting nothing more than a commercial for their product counter to the thread.

WizeAss

iTrader: (5)

GM engineers build quiet streetable fast streetcars.... not loud performing street monsters!

WizeAss

iTrader: (5)

a Good question.... wonder why TSP's L92's are going to use 2.18 and 1.60 valves??? is this only for a 4.1 bore application? or do they also disagree with Tooley?

WKMCD

iTrader: (2)

They may be the available valves - not sure. I never mentioned any names.

Brian Tooley Racing

iTrader: (13)

I didn't say they didn't make power, I said they are hard to cam, i.e. hard to get the cam timing events correct, namely the intake opening and closing events, and that is due to the intake valve being too large.

It seems to me that the GM engineers were trying to make killer power with very little cam duration, and that combination works. If you want to make record setting power on a 6500 RPM hyd cam street car the big intake valves and ports don't seem to be your friend.

There are more ways to make power then there are ways to skin a cat, it's all in how you want to do it. I have said it many times in this post and I will say it again, smaller valves make power easier because they are not hard to cam, bigger valves will make power but seem to be very hard to cam, for the average guy he will have more success with a head that has smaller valves. My only reason for making the first post in this thread was to give everyone the heads up as to what is going on with these heads. Before there were results from the ported heads in this thread I stated that big intake valves have the tendency to make the person who ports them to look bad, and I don't think a 10 HP gain made Richard look good, and Richard is a great guy and head porter. And as I have stated before, the heads are excellent bang for the buck but are not the end all as everyone thought they would be, and now everyone is seeing that.

SDB

iTrader: (7)

seems like the thing to do is build a cheap 408 iron block, or even a stock bottom end 364 cube LS2, throw the stock L92 heads with upgraded springs and L76 intake assemble (about $1628 for upgraded heads, TB, rails, injectors, and intake) and make very nice power for a DD. Probably 550 crank hp pretty easily with a small cam.

C_Williams

Although the damage is done, the following old adage sums up why someone should stop posting on this subject.



"It's better to keep your mouth shut and have people think you are a fool than to open it and remove any lingering doubt."

Juiced

iTrader: (2)

Charlie/Richard

Any ideas on how the deck on the l92's are going to hold up?

WKMCD

iTrader: (2)

I'm not sure there are a lot of people left here who really give a rat's *** what "someone" says anymore. At this point he's really just embarrassing himself. It's sort of sad.

edcmat-l1

iTrader: (10)

It has turned from informative to entertaining.........
Question for Mr Tooley, What kind of cams are folks running to make 500+RWHP with your heads on a 403? Lets compare apples to apples.
402/403 cubic inch, 90/90, with your best cathedrals, how much cam.......
And then we'll compare $$

tlaselva

Great thread.

Many opinions and ideas. Nothing wrong about disagreeing, and stating why. Just let's keep things mature and stay away from personal attacks.
We should encourage discussion especially in regards to something as complicated and controversial as cylinder heads, not attack someone who doesn't share our opinion.