Anyone know the limits of a 2g intake manifold? I'm having an issue with my power falling off after 6500RPM and didnt know if the manifold was holding me back. I'm making 445whp on a billet S259.

You're on the DKS 272's?

juanpac0 said:

You're on the DKS 272's?

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Yes. We degreed them in also. Could it be a valve spring issue?

If you worried about the intake manifold holding you back, buy a RVR intake manifold for $150 and call it a day. Are you on the stock valvetrain?

Big 28 GSX said:

Anyone know the limits of a 2g intake manifold? I'm having an issue with my power falling off after 6500RPM and didnt know if the manifold was holding me back. I'm making 445whp on a billet S259.

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Mustang dyno or dynojet? How much boost? What kind of timing? What air fuel? What type of gas?
I would say get a SMIM and a 1g throttle body or something even bigger. Not that the 2g tb is holding you back, but it sure isn't helping any.

Gamble97 said:

Mustang dyno or dynojet? How much boost? What kind of timing? What air fuel? What type of gas?
I would say get a SMIM and a 1g throttle body or something even bigger. Not that the 2g tb is holding you back, but it sure isn't helping any.

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Mustang dyno, 28psi, 20 degrees of timing (was getting kr above that), 12.0, 110. The 2g tb is bored to 57mm so im not worried about that.

Big 28 GSX said:

Mustang dyno, 12.0, 110. The 2g tb is bored to 57mm so im not worried about that.

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How much boost? And 57mm isn't very big. Add some timing and it shouldn't drop off any more. And deff get a SMIM.

Gamble97 said:

How much boost? And 57mm isn't very big. Add some timing and it shouldn't drop off any more. And deff get a SMIM.

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I edited my last post.

Judging by the information you've given, your car will most definitely benefit from an SMIM; especially since you say the fall off is from 6500+. Also, you may consider stepping up to a 1G 60mm TB (for the simple sake of rounding out the setup), unless you have a custom TB or something.

I would say a good SMIM definitely wouldn't hurt your 6500rpm+ power on your setup

Upgrading your intake manifold will be a plus, but will not be the limiting factor on making horsepower. It will always come down to what turbo you have.

50 trim with stock mani will make less power than say a 35r with the stock mani, but both will increase in power with an upgraded unit.

It's not holding you back on power, per se, it's holding you back on airflow. Anything larger than a 16g should have an aftermarket SMIM attached to it, or you'll be fighting for power.

A 60-70mm tb would also help.

i have thought about this too and my new gsx will be close to those numbers as well and from what i understand i have too keep the stock 2g intake manifold on there to be able to pass lovely NYS inspection and such any ways around this or is there something i can do to get a little more power?

It decreases volumetric efficiency in the upper RPM range from making it more difficult for the engine to breathe, which causes the lower airflow. With that said you can run it and make more power, but you'll have to settle for your powerband dropping very quickly.

I made my power on a stock 2g intake manifold with a 1g throttle body. Torque was falling extremely fast after peak boost, so it definitely wasn't getting as much top end as it would with a SMIM.

Hmmm very good information. I always wondered about this since i'm on a stock 1g intake manifold with a my old 2g Tb.

would it be wise to upgrade to a smim if using a turbo bigger than a 16g?

What size turbo?

like 20g, hx35

For the 20g i would just leave the stock one personally but for a hx35 depending on what hot side you use i would get a SMIM. Power can be made with out them though. But like others have mentioned 6500 is when they start falling off.

Yeah you def. need a bigger setup.

I have a Holset H1c and use a 1g TB with a Evo manifold.

setup im thinking running is ts divided manifold, hx35 or hx40 in ts housing, 275 cams.

Then a SMIM would be a good choice if funds allow for it.

well im trying to do everything right first. only part im stuck on is which jmf smim street or drag?

street

I would recommend either a race or a drag. I'm in the same boat but our goals might differ so the race might be better suited towards your set up.

http://www.dsmtuners.com/forums/bolt-tech/390886-jmf-drag-race.html