OK, I did a search, and didn't really find what I was looking for. I am building a 383 stroker, carb'd not fuel injected. I have heard, and don't know the person I heard it from, so I don't know if it is a reliable source, that it is possible to have TOO much flow through the heads. I bought a kit fomr Trick Flow, similar to the Holley SysteMAX kits, but much more power. Now, a guy wants to tradea pair od Edelbrock Victor Jr. Heads that are fully ported and polished but have no valve springs, and need to be put together, for my Trick Flow Twisted Wedge fully assembled heads. The victor Jr's flow 315 cfm intake and I don't know about the exhaust flow. My question is, can a better flowing head rob my motor of power??? If so, please look at my combo, and tell me if the Victor Jr's are too much for my motor.

SCAT 4340 Forged Crank
SCAT 4340 Forged Rods
Lunati Forged Flat Tops 11:1 CR w/64 cc heads.
Trick Flow Cam- 246/254 @ .500 lift Hydraulic Roller
and a 200-250 shot of nitrous.
The car will be driven on the street, not "track only" so the nitrous will remain unused except while racing.

 

Yes it is possible to have heads that flow too much, which will hurt your off the line performance. However, I'm not too sure what would be a good match for your setup, sounds like it would be hard to have a SBC head flow too much for the setup you're running.

I'm sure someone else can give your a more detailed answer.

 

You can't really have "too much flow"; but you can have a situation where you can't use all the flow you have, either because the rest of the motor isn't capable of turning enough RPM to consume that much air, or the motor is too small to use that much air.

It is, however, possible to have ports that are so large that at whatever RPMs you do operate whatever size motor you have at, the air velocity in the port is too low. When this happens, the air kind of stagnates in there, and the fuel separates out, and you lose thermal efficiency. It makes the motor run like it would if it was not warmed up, except it will run like that all the time.

Personally I'd rather have the Vic Jr heads than the TF ones, but that's just me. I understand them better. I would expect they would flow more. But, I'd have to wonder why this person wants to make that trade, as much as just the difference between the 2 heads. Why does he want your TFs, and why doesn't he want the Vic Jrs?

Remember, nitrous essentially bypasses the intake-side flow limits of heads. It's about like dumping liquid oxygen and liquid fuel into a motor. You still need all the exhaust flow you can get, but intake-side flow becomes much less important. Your cam looks like a very bad choice for nitrous.... it needs lots more duration on the exhaust than on the intake. You can't burn more if you can't move the spent gases out, and nitrous motors like lots of exhaust duration for that reason. Your cam is clearly a N/A cam optimized for a head with super exhaust flow and less intake flow; well matched perhaps to the TF heads in a N/A setup, but not appropriate to either the Vic Jr heads, or nitrous.

 

His reason for wanting to trade, is that his motor is complete, except for the heads, and he is ready to get it running. He is out of money, and anxious I can imagine. Like I said, his heads need valve springs, retainers, etc. All he has is the heads, with machine work done, and Manley super flow valves... I think. He is ready to bolt on something and go. I don't think there is any problem with the heads he has, they were brand new, had the machine work done, and have still never been bolted on to a motor. The only thing I could think of, would be that the machinist may have ported too much. But the work was done by a very reputable machinist here in North Texas. Not sure, I know I would be getting a damn good deal on the Vic Jr.'s, I just wanted to make sure that they would not hurt my motor. More input would be appreciated. Thanks guys.

 

With the kit I am using, Trick Flow guarantees 500 hp & 450 ft lbs of torque at the flywheel. With the use of certain other parts of course, including......
Edelbrock Victor Jr. Intake Manifold
Holley 750 dp w/Mechanical Secondary
10:1 CR
And also must be used on a long rod stroker bottom end


As you can imagine, I do not want any less power than that. I only want to improve upon it, and if trading for the better heads will hurt my power or torque, I obviously don't want to do it. Pleeease help me out and let me know as much as you can.

 

It won't hurt your power or torque. It may move the torque peak upwards in RPM, and will probably move the HP peak upwards in RPM too.

But there's alot more to making that decision than just the motor. How much does the car weigh? What gears does it have? What converter? Those things determine how much torque you need to move the car, and at what RPM the engine must produce it; you can't really build a motor in an information vacuum about the rest of the car, and expect a good match. It's a common mistake that people make, to build a motor that wants to run at 5000 RPM or above, but have gears that keep it below 3000 RPM all the time.

Another thing about the cam.... it has very low lift, which is of course consistent with TF heads, but not others. They design their heads in such a way that it's very difficult to use high-lift cams. It is a poor match with other mfrs' heads however.

I'd say either stick with the TF kit, or be prepared to change more than just the heads to get optimum results.

 

The car is an 88 GTA... bone stock, no suspension mods yet. I don't really know the weight. I am going to use a B&M turbo 400, with a B&M 3500 rpm stall, with welded internals for use with nitrous. ANd I am undecided on gears, not sure the best combo yet. I was told by Summit, who I bought the kit from, that the power range on the cam is from 3200-7000. Do you know if the roller rockers i got with the kit, Trick Flow 1.5 would work on the Edelbrock heads?

 

Actually, it is possible to have too much flow. There was an article about it in Hot Rod magazine I think. What you want to have is maximum velocity, not maximum flow. If it flows too good you will lose velocity and therefore lose power.

 

OK. I'm a newbie, how would I maximize velocity, if I were to use the Vic Jr's?

 

That's basically what RB said..... he just explained it more (which he's good at).

Velocity is air speed. Decreasing the area the air flows through speeds it up. It's kind of like putting your thumb over the end of a garden hose and the water shoots farther. Not as much water comes out in the same amount of time, but it comes out faster so it has more velocity.

Velocity is good for low-mid RPM torque. Max air flow (i.e. amount of air) is good for upper RPM HP. Having a huge intake runner slows the air down which doesn't give you as much low-mid RPM torque, and ...... well just re-read what RB said.

 

I know what velocity is..... but how do I maximize velocity, on a head that has such high flow?

 

You the installer don't have any control over that. The guy that ported them did however, to some extent. It depends on what they're set up for.... did he sacrifice a little flow, and shape them so that the air all tends to follow one narrow path on its way in; or did he shape them for max flow? A good head man can change the charateristics of a set of heads quite a bit, by where he takes away or leaves metal. Guys that do it for high-end circle track racers will port heads differently for different tracks, to get the torque curve that the car needs on that particular track, based on experience and RPM data.

 

you are paritally correct....

there is no such thing as having too much airflow in a head in any situation, more air in and more air out coupled with enough fuel is what makes horsepower. Well i left out the ignition part

What you are describing is what happens when your next door neighbor buys a set of stock castings and spends $400 on a porting kit and goes to town and hogs out the runners. Airflow improves, marginally, but the size of the intake runner is now hogged out to holy hell and the velocity through that intake port is crap and will do nothing but create a loss of torque and surging.

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For the person who wants to trade heads, i would tell the guy who wants to trade you want to go have them flowed and CC'd. The victor juniors start out with a lot of port already plus are they the high ports or not? if they are they require a different type of intake manifold. With the large CC those heads usually have you are talking about a rpm range up around the 7000rpm area...do you have any limitations or concerns about buzzing that high? Plus do these heads require offset rockers or custom size valves? It really starts to add up when you have a bare race head and you need to finish it up

 

Ive discovered the Hotrod people..are human also...therefore we have to add the" human factor" in what we read..

 

If you don't think it is possible to have too much flow , put a very high flow set of heads on a stock 350 and see how your engine reacts at low end-mid range!