Open Secondaries Early?? Take out Secondaries??

[Artesia]

Okay, here's the deal. I have a few questions:

1. WHERE are the secondaries located?

2. Can you cause the secondaries to open early?

3. WHY do the secondaries open so late at 3900 rpms? (gas mileage?)

4. What advantages would there be to the secondaries opening early? (more horses at the lower end of the rpm band...quicker response?)

5. Can the secondaries be taken out completely so that you're always at your full intake potential when on the throttle?? Is this recommended??

Thanks guys...I figure this will be decent conversation piece.

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- Brian C.
5576 Ragan Dr
The Colony, TX 75056
(972)625-2123
[email protected]

"We do not see things as they are...we see things as we are."

 

[89 SHO/SC]

The secondaries open to match the resonance of the intake and to allow for a flat TQ curve. Opening them early causes LESS TQ, As a Matter of Fact, opening them later on a modified engine makes for a smoother transition.

If they stay open, which you can do by unplugging the IMRC, you loose a ton of TQ/HP under 3600 RPM.

 

[93SHO]

1. Pop your hood. You see the runners right there... the "snakes". The longer ones are the primary runners, the shorter ones are the secondary runners.

2. Yes, you can set the secondaries to open when you want by programming an LPM.

3. The longer runners are there for torque... the shorter runners are there for more power. If you didn't have the longer runners for the low RPM range, you'd notice a loss in torque. The SHO is just starting to make its horsepower at 4,000 RPM.

4. There wouldn't be an advantage in having your secondaries open earlier. You might have a few more horsepower, but less torque... and torque is what turns the wheels.

5. I suppose you could disable them if you really wanted to... but I would definitely see no reason at all to do so.

Hope this helps.

-Evan

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1993 MTX.
Mods - Quaife, Baer brakes, 2" dual exhaust, Dynomax mufflers, H brace, Koni struts, front camber/caster plates, rear control arms, SHO shop springs, solid aluminum radiator, big bore butterflies, cold air, K&N, kevlar clutch, high flow cats, 80mm MAF, front and rear strut tower braces, 16" ROH Sniper wheels, BFGoodrich KDWS 225/55/16 ZR4 tires, and LPM

Sitting in basement - Garrett turbo (who knows...)

 

[noSHO]

It is totally pointless to have them open all the time. They were designed to be closed for a set period, leave it that way.

Mine don't open until 4150 or so, and the transition is really nice. I get hard power from about 3000rpm to 7500. You wouldn't want to have them open that late on a stock engine, though.

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-Dave
green/black 92

 

[Artesia]

Okay, cool. Wow, I had NO idea that the short and long runners both go to the same cylinders. I thought it was very odd to have some long and some short runners, but I understand completely now. That's FREAKIN' sweet! I've never seen an engine designed to do that before. Wow...very interesting. And yes, I understand now why you would not want the secondaries to be open early. Make sense. I thought there were just some secondary butterflies somewhere in the intake (small ones) that let more air in, but never thought there were that many and to that degree.

In the first gen Rx7s, people make the secondaries open either immediately or early...but they have carberators. So it creates lots of torque and horsepower quickly. Of course, that's a rotary engine, not a piston engine. Completely different.

And on the second gen Rx7s, I always take out my secondary throttle plates, because it makes for more airflow through the intake and adds some horsepower gain through the entire RPM band. Very nice little mod. In fact, you have to increase your timing just a tad when you take them out.

Thanks guys.

------------------
- Brian C.
5576 Ragan Dr
The Colony, TX 75056
(972)625-2123
[email protected]

"We do not see things as they are...we see things as we are."

 

[FAST4DR]

There are a lot of cars that have dual stage intakes now. There just not very elegant looking and mostly hidden from view. The SHO's intake should be in the New York Museum of modern art.

William

 

[Axianator]

The upper intake on the V6 SHO is just plain SEXY.

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'95 ATX with 98k miles
Stock with open intake
Soon: 80mm MAF and PCM tuning

 

[SHOTIME]

This is the link to the US patent.. Although its not working right now..
http://164.195.100.11/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1='4,809,647'.WKU.&OS=PN/4,809,647&RS=PN/4,809,647




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Eric
mailto:[email protected][email protected]</A>
My Web Space
New England SHO Specialists

 

[drivinhard]

I did some testing with the runners open all the time.

Using my old 89, and only 2nd gear from a start (really makes the low end work) the 89 could run a 6.7 sec 0-60. Opening the runners the whole time, resulted in almost a 1 sec slower 0-60 (mid 7's). The sub 4k torque just goes in the toilet.

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White 92
SR71SHO - racer '89

 

[Artesia]

**** yeah! I like when people are willing to test stuff out like this. Thanks for the info man, you rock!

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- Brian C.
5576 Ragan Dr
The Colony, TX 75056
(972)625-2123
[email protected]

"We do not see things as they are...we see things as we are."