turbo intakes?

[doncannon]

Hello All,

Which intake is better for turboed engines...single plane or dual plane. :confused:
Thanks in advance,
Don

[EWC]

Single intake is worth about 20 cfm more than the dual plane .

[john8662]

I agree with EWC here, the single plane manifold would probably flow more air, I will be swapping out my dual plane manifold on my 86 truck when I turbo soon for the single. I don't know how much it will help, but couldn't hurt since I already have the parts.

[DmaxMaverick]

The dual plane intake offers more torque at lower RPM's, but falls a little short at higher RPM's. The single plane is just the opposite. This is true for N/A engines.

That being said, with a turbo, the engine is severely hindered off idle as it is. Changing to a single plain intake may help the top end, it would most likely cripple a TD at its weakest point...accellerating from a stop. This is exaggerated with a manual tranny, as the auto torque converter allows you to build RPM/boost sooner. From idle to the RPM at which the boost comes up, the engine is essentially N/A, with additional restriction in the intake tract (smaller tubing, turbo). Disable your wastegate and you can really feel the difference.

Before you change your intake, weigh your needs with what you might gain. Unless your rig is on a dyno, or you pull steep grades all the time, it's my opinion that you won't notice any gain, but will feel the loss. Economy will probably suffer, as well. It may be a lot of expense for a dissapointment.

[doncannon]

thanks guys,

I appreciate the advice. Now what do i do? I will probably change injection pump and injectors in the spring so what ever I do I will feel a gain from that...maybe I will just change intakes before to see what the difference is and then back if no improvement. after all intake gaskets probably are not that expensive.
thanks again,
don

[NH2112]

From what I understand, single and dual plane intakes don't affect diesels the same way they do gassers, because there's no throttle plate restricting airflow. Isn't the intake that flows more air into the cylinder going to make more power at all RPM, assuming there's sufficient fuel? Back in the days when I actually gave a damn about gassers, I thought single planes basically made more horsepower at higher RPM because the shorter, wider runners flowed more air into the cylinders, while a dual plane has longer, narrower runners that flow less air but at a higher velocity to make better low-end torque.

[doncannon]

Yes NH2112,

that is the way i have heard about the gassers, but I am not sure about diesels. will the single flow more with a turbo? It would be less restricted and flow more at low and hi rpm? right?

Thanks,
Don

[DmaxMaverick]

....It would be less restricted and flow more at low and hi rpm? right? Yes, it would seem so. But no. The plenum, if ported and chambered properly, will work like a header on a N/A engine (or expansion chamber on a 2 cycle), in reverse. The dual plane takes advantage of intake pulses, which helps with low RPM power. With a turbo making boost, this becomes moot, as the intake pulses are negated by the pressure. A single plane intake, having all the ports positioned in common fashion, cannot take advantage of the pulses.

To answer your question, the single plane intake will flow more air if you are blowing air through it (less restriction, like you said). It will not flow more air into the cylinders at low RPM's. At low RPM's, the restriction is negligible, as there is not nearly enough air passing through it to be slowed by the dual plane design.

Cadilac, years ago, designed and implemented an intake that had variable porting/routing. It optimized the intake pulses throughout the RPM range. The power gains were very substantial.

If you have both, try both. It'll only cost you some gaskets, and some time. You may be surprised and notice no difference in any case, or it may be astronomical. You won't know for sure unless you try.

Good luck.