How Much Power Can Ported Stock Parts Make



How Much Power Can GT40 Parts Make?

Seems as though the Ford GT40 family of intakes has lost the respect it deserves. I see guys post all the time that it’s an “old” design and that the newer aftermarket intakes are better. Well, I’ve ported about 900 of these babies so far and as a result I have had a lot of feedback regarding the results. Some magazine based testing has been done that also shows they are hard to beat on 8.2 inch SBF STREET engines. I’ll go through some of the results just to give you a flavor of what they are really capable of.

I ported an Explorer intake for a guy in Texas who was pretty happy with the way the engine ran but his buddies kept telling him that he’d make more power with an RPMII or a Holley (they both perform very close to each other). So, they wore him down and he bought a new RPMII so he could make more power. After he installed the intake, here is the mail I got from him after dyno testing and driving the car.

From:"Robert Pearson"

To:"Thomas Moss"

Subject: Re: hey this is the dyno graph for the explorer

Date: Sat, 6 Nov 2004 22:18:06 -0500

hey man i gotta get u the dyno graph of the rpm 2 compared to the explorer with your lower ported, all i can say is your intake kills the rpm 2 i lost 24 ftlbs of torque and 7 hp and under the curve the performer rpm2 could not compete on horsepower or tq the intake is coming off u will see more when i get the graphs on the same chart, oh and the explorer is going back on u should have good info to post and this was with nothing else changed i'll definetly recommend your porting to people thanks

Robert

----- Original Message -----

From: Thomas Moss

To: Robert Pearson

Sent: Wednesday, October 20, 2004 10:50 PM

Subject: Re: hey this is the dyno graph for the explorer

Much appreciated - looking forward to the RPM graph.

Robert Pearson wrote: well i don’t have and website or anything i don’t know how to do all that stuff, lol here are my mods

afr 165 emissions legal heads, 1.6 roller rockers, explorer intake with your ported lower 70 mm tb, 75 pro m maf

calibrated for 19 pound injectors, sct chip with the calibration for the 24 pound injectors, under drive pulleys timing

set at 14 degrees, p headers, with bassani off road x pipe flowmaster cat back, aod trans with wide ratio kit, shift kit

3200 pi converter soon to be raised someday, msd ignition, 3.73 gears, and electric fan kit.

well i think that’s everything i should have the intake on next weekend the 30th - best times so far are 12.77 @

109.70 if u needed those.

thanks man

Robert

Here are the dyno tests he had done on both intakes:

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So, off came the RPMII and back on went the ported Explorer.

Here is another example of a ported GT40 that was replaced by a ported Holley. The Holley is down 6RWHP in the 2,500-6,000 rpm band and is 10-20RWHP down from 3,000-4,800 rpm and gains that back only in the last 400 rpm.

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I became aware after writing this that David did some more tuning on the above Holley SMII combination and got some better numbers from it. Power above ~4,800 rpm was improved considerably as the below dyno shows.

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When you run a blower, often you don’t need as much intake as when you are N/A. A car can be much more fun to drive if you can keep torque below the blower curve up to maximize acceleration until boost comes in. Jim found that out:

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I often hear “we don’t race dynos”. Well, that’s true and sometimes a dyno peak number does not reflect the full capability of what a car will do at the track – one case in point:

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All else being the same, the engine that has the most area under the torque curve in the intended use rpm will be the engine that ETs best at the track.

I also hear that the GT40 family of intakes is done at just about 300HP to the wheels. Not so if you’ve done a good job of selecting your parts. I will say that they are rpm limited to about 5,500 rpm in most cases so if you do most of your driving there or below, you’ll be happy with these intakes. If you want to make power over 6,000 rpm, choose a different intake or work with Anderson Ford Motorsport who have designed cams for these intakes that let them make power over 6,000 rpm. Let’s look at some combinations that have made power over 300 RWHP with these intakes:

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If your car is heavy, that is another reason to stick with a GT40 family intake over a larger cross section intake. You really need to concentrate on making a broad torque band or you might be disappointed:

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What is porting a GT40 family lower worth? In most N/A cases it is about 15RWHP and up to 30 or more for forced induction. Here is one example where the only change was the porting. The rocker stud damage occurred between pulls and was not a factor in either.

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Here is the dyno graph. Gains are almost always across the board when done right because the intake is flowing more efficiently at all times:

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The ported GT40 lowers can also be used with Box uppers to mate with blower applications and make some pretty decent power.

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And finally, I see some saying the original Performer is a better intake. While it’s a nice piece, it holds no big edge over a GT40 family intake, either ported or stock.

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Here are some more random captures from feedback provided to us:

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Well, I hope this is some real world information that will show that these intakes are very capable if they are applied correctly.

Tom [pic]

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