I can definitely feel a difference in throttle response with the double throttle butterflies removed. You could simply disable the function by wiring the butterflies open, but I could not feel a difference when I did that. Easy mod to do if you drill out the screws holding the plates in.

For those who don't know how to do it www.rx7turboturbo.com has a good diagram. There are also numerous references on the forum if you search for it.

1. Pull out the vacuum hose to the double throttle actuator.
2. Plug up vacuum hose.
3. Remove actuator.
4. Remove double throttle butterflies and shaft (easiest way is to drill through the screws...they're very stubborn)
5. Plug hole in UIM.
6. Easy on the throttle when the car isn't up to temp.

Should take less than an hour to do.

 

what does this do exactly? do you gain power?

 

how much diffrent is it with the plates removed. i dotn think my dashpot works right anyway. can u hold a steady 15-10Hg quite easily with your foot? on the seq setup

 

no gain in power, it just cleans up the airflow a bit. The double throttle butterfly valves cover ~20% of the intake passageways. Since there is less turbulence in the UIM, air gets to the engine faster...resulting in quicker throttle response.

I remember reading about someone who conducted some airflow tests on the throttlebody + intake manifold...stock had something like 82% efficiency... taking out the double throttle plates added about 5%. I think he also polished the intake tracts, but it yielded very minimal results. Can someone confirm this?

kahren> dashpot? hold 10-15hgs with your foot? Im not sure I'm following. Im running sequential setup, vacuum is fine..the modification doesnt alter the idle or affect anything during startup.

 

I did this mod a long time ago but I still have not gotten to try it out because my ecu has been over a month getting to me Hopefully soon though.

 

i personnaly saw a 1 PSi boost creep of more so i guess it really flows better.

 

i did it and also saw better results

 

What did you guys use to plug up the hole left over after you removed the butteryfly shaft?

 

I used some silicone gasket maker and a fat bolt. I sanded off the edge of the bolt so nothing would be sticking out, gasket maker to ensure that it sticks in there. Some people use golf tees, duct tape (kidding)

If you want to be super professional, you could weld a bolt in there and then sand and polish it, as well as making a shiny accompanying block off plate.

 

Then again, it IS on the rear of the UIM, hard to get your hand back there, yet see...I voted for large (fat) bolt and some gasket goo ...

K

 

Did you guys have trouble with your idle after dong the mod???

i ask because I recently swapped my tb for one with the AWS removed...

 

Garfinkle plugs the holes with threadrd plugs from the out side so they can not back out into the motor then he smoothes the inside ends to match the throttle bore .He also opens up the area where the old plates were for better flow.

 

how's throttle response w/o the double throttle. i've heard there's slightly less responsiveness. also you might get dangerously lean at tip-in cause there's more air now. if you suddenly pound the accelarator from off throttle, that gush of intake air is more than the computer is programmed for and you might go lean.

 

WHAT ABOUT CHANGING THE THROTTLE BODY ALL TOGETHER. LIKE PUTTING A Q45 THROTTLE BODY INSTEAD...I'VE SEEN SOMETHING LIKE THAT BEFARE....BUT DON'T KNOW HOW IT WOULD RUN...OR IS IT EVEN WORKS!

 

I understand your idea, but the throttle body itself on the FD is not much of a restriction. The double throttle butterflys are at the entrance to the upper intake manifold, those are what can cause a bit of restriction. A Q45 is also a Nissan motor, sounds like a lot of custom work to fit it to a 13B.. I thought they did that upgrade on Skylines?

 

I've thought about replacing it entirely also. I was thinking of using individual valves for each pipe and positioned them closer to the intake ports-like at the top of the lower intake manifold. Generally speaking what are the advantages/disadvantages to shortening the intake track between the ports and the valves?

 

i mean t while driving, if u are not on boost, u are at what like 15-15Hg, i was wondering how hard it is to drive on vacuum with the plates removed, or if it just starts boosting uncontrollably?

 

I have been running this mod with it wired open, but I never noticed any difference. I am now rebuilding the turbos and intake and I have removed the DTV. I did not tap or glue the hole. I made a small block off plate from aluminum. I used the actuator bracket to transfer the holes, and simply cut and drilled the plate (10 mins max). I used an o-ring to sandwhich in the recessed shoulder.

 

unless you're pushing over 500rwhp and got huge ports, there's no need to change the im. it's not a restriction. shortening the runner length would give you more top end, but it would be dog down low due to the rotary's lack of torque. the im volume and runner length was carefully calculated to be in sync w/ the rotary, so changing it would do more harm than good. plus using the stock lim would not alleviate any of your restrictions, as the interface btwn the lim and intake ports are the bottleneck. you can easily see how the im runners taper from big and round to small and oval at the very end, and that's where the restriction is. ask anyone the lim flow the least cfm throughout the whole im.

btw, i asked a very experienced rotary builder about removing the double throttle plates, and he said not to. the advantage is minimal at best. he says the intake charge has to go throught the fist set of tb's already, so those are going to determine the volume of the intake air. removing the second set of butterflies isn't gonna do anything, because they're the exact same size as the first set. that's what HE says so no one flame me.

 

Does removing the double throttle do anything for emissions? I have a new FD I’m trying to have pass smog in CA and it did not come with the double throttle already. Thanks everyone.

 

It's just there to delay the effect of the secondary butterflies in the TB so that the ECU gets a fraction longer to respond with the correct fuelling to ensure it doesn't run lean. It has no affect on emissions in a test.

 

Thank you Ceylon. I didn't think so but always best to be sure. Thanks!

 

is this worth doing on a single turbo/apexi set up? or is this more for high hp/ track cars?

 

^^^ Unless you're trying to really clean up the engine bay and/or are installing something that requires those butterflies to be removed, I don't think it's really "worth" doing at all.

I'm single turbo and I did just recently eliminate mine to accommodate the JP3 brake booster line. I noticed no difference in either power (although its not like I had a dyno or anything) or throttle response. And I'm usually pretty sensitive to that kind of thing.

That being said, it is an easy job to do in the grand scheme of things so I wouldn't turn my nose up at folks who just want them gone. But I'd feel guilty about listing that modification as any kind of "power adder".

Just my experiences though.

 

First off, this thread is literally old enough to vote....

Second, the double throttle is only there on manual cars to limit power at cold coolant temperatures. Once it's warmed up it stays open all the time - I've tested and verified that myself. On automatic trans cars it does some magic when shifting gears, but if you have an auto car you have a much larger problem .

You can remove it, it just cleans things up some but really doesn't make any more power or fix anything. Banzai Racing's block off plate kit comes with a plate for the DT, if you remove it you have to make SURE you get it blocked off well so you don't have a funky vacuum leak.

Dale