Contour Enthusiasts Group Archives Forums Modifications Duratec Performance The harsh truth about secondary removal

Po-Jay, I certainly didn't mean to criticize your mods and, as you say, I probably did miss the point.

As an SVT enthusiast though, my feeling is that despite all the performance mods you can make on an SVT, if you testdrive it on a track together with a stock SVT and with different drivers, the only noticeable difference would be in the drivers' skills.

I do understand however the personal satisfaction one can acquire with any mod that leads, even theoretically, to an enhancement of the car's performance.

BTW, I hate the WRX. It is an ugly and boxy car probably more suited for autoX.

Po-Jay, thanks for dynoing this mod. It's good to have a quantifiable understanding of why the secondaries are there. I personally got kinda tired of people removing the butterflies and making nebulous statements like 'it pulls like mad up top now'.

These results are not surprising - think of all the hours Ford Powertrain engineers spent dialing in port sizes, runner lengths, etc. Yes, some other components like the exhaust, etc have some serious comprimises to them, but Ford didn't go through the trouble of adding a secondary intake system just because it thought it would lower engine output.

-Kurt

This mod is never going to be all it could be without a chip being developed to revamp the spark/fuel curve under the IMRC point. If you go over to stangnet or corral.net, they actually sell IMRC delete lower intake manifolds for the Cobra... And there are 2 chip makers there that have chips developed that take into account that the secondaries have been removed and makes the car drive like normal... I belive slight losses are still found even with the chip.. but overall the cars drive much better and you never have to worry about the damn IMRC openning... Its worth all this just to get rid of the IMRC... Sure ford spent time and money developing the secondaries for our cars, but they spent about 2 mins on this damn IMRC, and it ruins the whole system!!!

I was working with Duratecperformance.com to help get a chip from diablo developed to delete the secondaries, but couldnt find somebody in Boca Raton, FL that was willing to take apart their intake system to mod or install a pre modded secondary delete lower intake manifold. Diablo says it would be no problem if they could get a car in for testing that has this mod done.. But everybody wants something for free, so we are still looking.

I also think that the full rod removal MAY be a good thing and low RPM losses may be minimized but this becomes a complex multistep mod. Need the spark advance & A/F ratio retuned. Need to open up the UIM (which is several mm smaller diameter than the LIM) and probably t.body & MAF meter (and of course exhaust) to get the best gain. Demon did all this but he has some other new mods so I'm not sure if his dynos will give the answer.

On the good side, a 2-4 HP gain from removal of only the plate suggests that optimizing the butterflies (similar to the t.body) may give some gains without the issues of removal.

WellI dont know what I gained from the removal. I never dynoed before they were gone. Yes, I will get a chip to advance the timing then I should be set. I have a 65mm TB and S-afc with true duals and seom other stuff. I dont have a New Maf yet but I will get one. You need to have some stuff done to your car for this mod to make nice effects. I pulled 181.2 Hp on the dyno and I have a 1998.5! I though that was good and If I get a chip and MAF I expect much higher..

So the mod helped me. I also compared #'s with a SVT with the valves in place and we are around the same numbers at 5k.

Joe
Ps. I can scan my dyno sheets and send them to someone if they want to post it. I dont know how to post pics and stuff.....

With the secondaries gone, there just isn't enough air VELOCITY to fill the cylinders effectively/effeciently. Too much surface area in the two intake runners. That's why your power is down.

The secondaries are there to give you a flat torque curve. Trust Ford on this one.

In response to those that say that Ford put them there for a reason, I have one statement... "To get better than 18MPG!" It is in Ford's best interest to make cars that get as good fuel effiecientcy as possible. I trust Ford on that one. So it sounds like this mod may need some extra work to be effective... Okay. I do not believe, however, that it is Too much air for the engine to handle... That is not the case. Open the TB/Maf/Exhaust and it will have the ability to push and pull much more. You have to trick the ECU with the S-Afc or something like it.

Well, my money is on Ford trying to increase low end torque by using the long/short runners with the IMRC. (I always forget if long or short gives better low RPM torque.) No point is putting out a V6 that is a dog in daily driving. I would be quite interested if anyone can match torque below ~3000 RPM after removal of the secondaries with some tuning.

Jay,

You can remove the rods without cutting them. Clean the rods with carb cleaner to remove any buildup, then slide them right out of the hole. You can use some small bolts with silicone on them to seal off the holes temporarily.

My 3 liter has enough low down torque off of idle without the secondaries to light up the tires to where I have to feather it (235/40/17's in case you were wondering). SVTJOE1's dyno was impressive as well. It takes a lot mof mods and some amount of tuning to make the gutted secondaries work well. Who cares if I might get 20-30 more below 2,000 RPM... I never drive the dang car down there anyway and the tires can't put it to the ground even if I did.

Your experience with pinned secondaries SHOULD be negative. Pinning them is just a way to see if the low end losses are worth it on your car with your mods and driving style.

Not enough velocity eh? Add on a 70mm TB and what do you get? An SE that walks modded SVTs is what I got. :p Judging by my dyno graphs, my torque is fairly flat from 3K up to just before redline, HP could use a little more air above 6K. My SE UIM is holding me waaaaaaaaay back here, as are my cams, heads, etc. Time for stage two...

FYI PA, short = high RPM HP, long = low end TQ. You other 3 liter guys, look at it this way... the '01 and newer 3 liters don't have pri/sec... just a large oval port. Wonder why???

I like my results so far with them removed.

Power comes on at 2500rpm. I never drive below that.

Also mileage for the first 2 tanks fulls (lots of spirited driving) = ~24mpg
I expect that will go up a bit too.

Overall power is great. Throttle response is awesome.
I also had to install the TH fix for the first time. Tiny hole! Man that's cool...