Port And Polished Heads

it possible... my last dyno run i had i was down 30hp with my set up...hitech 2's mph ported heads.....BUT, the tune was only half done while i was on the dyno and the dyno wasnt working correctly to that MAY be the reason i was down on power

ill be able to tell you tomorrow when i get retuned since i have the set up youre looking for

I've never heard this, but am curious HOW/WHY this would reduce hp/tq?

cMcKinney97-GT said:

Ok so today I was told that ported and polished heads with Hitech Stage II's cams can actully reduce your horsepower and torque by 40/30 instead of help. I'm looking to get 300rwhp and I would hate to spend money on ported and polished heads if I lose Hp and Torque with them. I was wandering if anyone else has heard this?

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Ok, I really don't know all that much about these motors, but this is what I've gathered from years of reading forums online. Take it with a grain of salt.

You don't actually "lose" that torque and horsepower. Rather, it is shifted farther up the RPM curve, i.e. peak horsepower and torque may occur as much as a few thousand RPM higher. So let's say your current peak torque is at 3500 rpm and peak hp is at 5000 rpm. Now we'll assume for simplicity purposes, that very highly ported and polished heads and high revving cams move your power curve up 2000 rpm. Now, your peak torque is at 5500 rpm and peak hp is at 7000 rpm, and your torque at 3500 is like your torque at 1500 before the heads and cams, and your power at 5000 is like your power at 3000 before the heads and cams. Now this can be a good thing if you are actually going to spin it out that far and use all that power, but if you are only going to spin it the stock amount (6000ish rpm), then you aren't using most of the power from the heads and cams and could very easily see a lower power and torque numbers.

This is obviously a very over-simplified version. There are many more factors that play into this, but that is the general gist.

Airflow through an engine is more complex than just flowbench numbers. The flow velocity and tuning -- length and volume -- of the intake and exhaust tracts are very important too.

For velocity, think about a venturi in a carburetor. Essentially a narrowing of the passage, air velocity picks up as it flows through the venturi section (assuming the flow remains laminar): the resulting pressure drop draws fuel out of the bowl etc etc... This is basic physics. When you hog out ports and runners you increase their volume and cross sectional area and in doing so, you can actually cause the flow velocity to slow at lower RPM. Flow velocity is a key term of a "ram effect" that uses the momentum of the moving column of air in the runner and port to help with cylinder filling at low RPM. The benefits of the hogged out port often show up as less restriction at higher RPM and better cylinder filling up there ... to a point.

Tuning is another factor that isn't so much changed by porting as it is by swapping things like intake manifolds and headers. An intake runner -- a "pipe" from valve to plenum -- on your engine can be thought of as akin to a musical instrument. The length of the pipe, the density of the air and so on all dictate at what frequency the pipe will resonate (i.e. support a standing wave), which is excited by the pulsations coming from the intake valve (and, if you want to get more complex, the other intake valves in the engine exciting the plenum end of the pipe...) These standing waves can also provide a "supercharging" effect, with a pressure node at the valve helping to cram more air into the engine. Long runners naturally tune to lower frequencies (i.e. lower engine RPMs). This is why 1980s GM TPI engines had those long, curved runners: low RPM torque. Even the plastic intake on the 4.6 provides nice, long runners looping down into the valley. But long (tuned for low RPM) and thin (velocity) runners tend to be restrictive at high RPM. So you open them up and shorten them. Resonance occurs at higher RPM and the increased cross section reduces high-flow rate restriction. The result: Better high RPM power, often at the expense of low RPM torque.

One solution might be something like the FRPP manifold for 4V engines:



This is a "dual mode" manifold. When the butterflies are closed, air is forced through longer runners giving a decent low-end performance. When the butterflies open, the air is free to enter the runner at the top, giving 1/2 the length to run to the port, giving better high RPM performance.

Porting is a science. Good porters know it's not just about removing every molecule of material but about balancing cross section with good flow management around corners etc etc. Definitely not a thing an amateur should try.

Did you have the heads tested on the flowbench before and after the port work?

Do you have a plot of the 266rwHP dyno pull you can post?

What was the AFR was during the pull?

What was the timing?

Who did the tune? How much did the car start with? Is 266 the best the tuner could obtain?

What other mods does the car have, specifically intake and exhaust? Was it a Mustang Dyno, Dynojet or ____ ??

As well, take whatever any vendor says with a grain of salt, especially rear wheel horsepower numbers. 266rwHP is ~306 at the crankshaft which is a pretty respectable number for a normally aspirated 2V.

cMcKinney97-GT said:

Ok so today I was told that ported and polished heads with Hitech Stage II's cams can actully reduce your horsepower and torque by 40/30 instead of help. I'm looking to get 300rwhp and I would hate to spend money on ported and polished heads if I lose Hp and Torque with them. I was wandering if anyone else has heard this?

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You can get 300rwhp without a port and polish with the Hitech Stage IIs.

cMcKinney97-GT said:

Well I had my cousin (who's going to school for maching) p&p a set of pi heads I had, bought Hitechs stage II's and put on my 97 for pi swap. Last Friday I took to get tuned and only made 266hp and 278ftlb. I know the heads are not prefect but Hitech's website says stage II cams make 300rwhp on stock long block, so i called them up and asked some questions and he said you'll lose 40hp and 30ftlb with p&p heads. Here is the link to there dyno gragh...
Hitech Ford 4.6 / 5.4 2V N/A Stage 2 Camshafts : Hitech Motorsport Inc, Performance EFI Tuning / EFI Dyno Tuning Experts - Elk River, Minnesota - Midwest Region

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There's possibly some of your problem right there: you need heads and cams that work together. For example, high rpm heads + lower rpm cams wouldn't make much power because the two don't compliment each other. I don't know this for sure, but I get the feeling the Hitech stage IIs are designed to work with the stock heads. Plenty of folks are making 300+ rwhp with those cams and stock heads. Scupking is; I've got a buddy with a 01 Bullitt running those cams, stock heads, and full bolt ons making 315 rwhp.

trinity_gt said:

One solution might be something like the FRPP manifold for 4V engines:



This is a "dual mode" manifold. When the butterflies are closed, air is forced through longer runners giving a decent low-end performance. When the butterflies open, the air is free to enter the runner at the top, giving 1/2 the length to run to the port, giving better high RPM performance.

Porting is a science. Good porters know it's not just about removing every molecule of material but about balancing cross section with good flow management around corners etc etc. Definitely not a thing an amateur should try.

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My question is does anybody make an intake manifold like that for the 2v? Honestly I've never seen anything like that before and I'm curious now.

tikibeast said:

My question is does anybody make an intake manifold like that for the 2v? Honestly I've never seen anything like that before and I'm curious now.

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Not that I know of. "Variable resonance" manifolds aren't new. I used to have a 1994 Ford Probe GT (with a Mazda 2.5L V6) that had something similar in its intake. They even touted it as "VRIS" - variable resonance intake system" - or some such:



That system actually used butterlies to optimize both runner length and intake frequency to maximize torque.

I've not seen anything like that for the 2V though. It could be partly due to the fact that the stock 2V has a relatively low redline and thus may not really benefit that much from shorter runners. There are short-runner-only manifolds out there like Reichard racing's:



but they're really designed for engines that can spin into 4V territory and which have cams and heads to match.

It'd be neat to see if there'd be any benefit to making such a manifold for the 2V. I doubt such a venture would be cheap though.

trinity_gt said:

Not that I know of. "Variable resonance" manifolds aren't new. I used to have a 1994 Ford Probe GT (with a Mazda 2.5L V6) that had something similar in its intake. They even touted it as "VRIS" - variable resonance intake system" - or some such:



That system actually used butterlies to optimize both runner length and intake frequency to maximize torque.

I've not seen anything like that for the 2V though. It could be partly due to the fact that the stock 2V has a relatively low redline and thus may not really benefit that much from shorter runners. There are short-runner-only manifolds out there like Reichard racing's:



but they're really designed for engines that can spin into 4V territory and which have cams and heads to match.

It'd be neat to see if there'd be any benefit to making such a manifold for the 2V. I doubt such a venture would be cheap though.

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Huh, well a lot of this is new to me, I've never really dug into much beyond repairs as needed, hands on modding is a whole new journey that I'm enjoying...or will enjoy again once I get this #^$% clutch done...thanks for the info.

cMcKinney97-GT said:

Well I guess I'll use the money I was saving for a set of Patriot heads and buy some stock heads, which are way cheaper so not all bad news right, spend less money and make more power, can't go wrong with that

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cheaper is exactly what you are going to get

i have to deal with patriot heads everyday, save for something else..they are total chit...if they dont immediatley leak out of the box, they will soon...95% of the patriot heads that we send out from here come back due to fitment issues or something was leaking or some other ridiculous problem..

actually, the last 2 heads that came back, one was for a 4.6 and the valves went bad after 2 months and the other ones were for a 5.0 and were cracked in almost all of the intake ports...

so please dont buy patriot heads!

no not yet...my tuner is a d bag and keeps blowing me off....supposedly today it will be getting done...

ive noticed that as well...the only reason my heads are ported is because my old set up was for the vortech i was running so i had the heads ported for it... the new set up called for higher compression so i got rid of the blower

tikibeast said:

My question is does anybody make an intake manifold like that for the 2v? Honestly I've never seen anything like that before and I'm curious now.

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BBK does, but I think they will never release it....

BBK: 1996-2004 4.6L 2-V Mustang Dual Stage Intake Manifold

P.S. the damn thing is $999!!