Hi again! Im about to get the aussie Hurricane, and my question is about the top speed of the car. I know that longs manifold increase torque, reprise and acceleration in low-midle range... but will be any IMPORTANT lost of power at top speeds??
I never use it at high speeds when traveling, so Im not looking for a better final speed... Im looking for acceleration and torque since 0.

Is there any rule to know that? will I get a better top speed too? Will I lose? In taht case... of how many mph less are we talking??
The engine is a stock cam, improved in compression and has a 2bbl 220 cfm.

Ill get that manifold because it has been my dream since I knew about the hyper pack Valiants!

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Mopar or no Car!

In my opinion on a bone stock engine you are wasteing alot of money that can bee spent better elsewhere.Guzzi Mark

Mark is correct, on a stock slant six you will not notice any loss as the camshaft looses power after 4000 rpm anyway...

In my experience using the clifford hyperpak on the street, it makes the best use of the low end torque, if the manifold is split it keeps a fair amount of nice midrange power (in the 2000-4000 rpm range). That being said the intake starts to have ram effect in the runners at about 3500 rpm, so...technically you will be shooting for rear gearing and tire sizing to make the best use of your engine build, I would start planning a little larger cam and more compression and headers/dual exhaust to make the most use out of the engine/intake combination.

I doubt you will know if you lost any power at 'top speed', given the common rear ratios and tire sizing your cam will nose over at about 90-100 mph on the straight away (you have a nice 30 mile stretch of road to test that on with no police around, right?)

I know that if you go about 9.2:1 and one of the "short" cams (like the comp cam 252/252 .435), you won't have a problem from idle to about 5500 rpm (so you can push it up to 125mph if it will take it).

-D.Idiot







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I got some head work and dual exhaust already. I want to work the ports in the future, and may be low down the head a bit more.

Thank you again Duster!

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Mopar or no Car!

If your carb really only flows 220 CFM then you'll reach that limitation long before most any manifold becomes a restriction. The original Holley 1920 flows in the neighborhood of 235 CFM.

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Joshua