sohc to 2nd butterflie or not to 2nd butterflie, (poll)

[lucky03602]

hello. i have a 90 240sx sohc ka24e. i have a seperate extra engine and i have the intake mani off, im currently looking for a write up of what i dont need on the intake, and also removed the 2nd butterflies.

i searched a little bit and found out that about half and half keep or dont keep butterflies in and for various reasons. most of the time they kept theirs in if it was a daily driver.

i plan on turbo'n this sohc and obviously want more airflow, but if the flies make more torque at lower rpm's, i think id rather keep the torque...

opinions on how u feel about keeping or getting rid of 2nd butterflies in a sohc turbo'd motor (t3/t4 if its going to matter)

[FabroKA]

they do make more low end if they are in BUUUUUUUUUUTTTTTTTT! they zap red line pull because they make turbulance and flow resistance. but if your not good at afc tuning leave them in you will have a hard time controling idel and launch if you don't.

[PapaSmurf2k3]

im all about making things more simple... take them eff'ers right out, then remove all the vac crap that goes to them.

[Edub1]

Keep them. Engineers don't get paid to add pointless expense. They are there to increase manifold flow in the lower RPM range and improve low RPM VE. They open at 2500 RPM under load and will not cause tubulance.

If you take them out, low RPM performance will suffer.

[WDRacing]

Swap in a KA24DE motor and you'll benefit from it in everyway...sorry SOHC guys.

WD

[lucky03602]

nah, even if i had all the parts to do it here right now i wouldnt, everyone always jumps to the sr or de and not many ppl actually use what they got. im going to show the ppl around where i live, (one with blacktop sr, other with de t3/t4) that my pignose single cam can run with them just as fast if not faster then they can go!!

SINGLE CAM PIGNOSE 4 LIFE!

[WDRacing]

Hows the weather up there in NH...has to be getting cold. I loved just under Nashua in northern MA for 18 years before I went into the USAF. I miss NH, one of the most beautiful states in the union.

WD

[lucky03602]

well as far as it getting cold, some mornings its a little nippy yeah. i work outside all day everyday trimming power lines and stuff so im kinda used to it...

id rather be up here in the snow then down south (agian) or somewhere where i gotta worry about floods/hurricanes/tornados, etc..

i do like it up here, next to no drama out of the way it is nice.

currently im living in souther nh 15 minuites from keene, nh

[nelson8708]

Keep them. Engineers don't get paid to add pointless expense. They are there to increase manifold flow in the lower RPM range and improve low RPM VE. They open at 2500 RPM under load and will not cause tubulance.

If you take them out, low RPM performance will suffer.

Appearently the engineers changed their minds because the 95 and up ka24de dont have the secondary butterflies. I am also building a extra ka24e and i have already removed the secondary butterflies. It is simple. Remove each plate from the runners then remove the set screw in between the two middle runners then slide the rod out. The rod didnt come out easily for me so i cut it up and pulled out each little piece. What i am wondering is if i should weld the small holes that connect the runners right before they enter the head since the rod is now gone. Will probably end up leaving them. The only other thing is that you have to have the hole where the rod is exiting the intake welded shut.

[WDRacing]

Also for the record...anything in the way of airflow, especially in the runner, will disrupt airflow. Nissan designed this motor under the thought process that Americans don't like turbo's or high rpms. That all we want is low end V8 grunt. So they made a NA stroker 4 cylinder...

Lose the butterflies and add boost. Want more lowend grunt, bump off boost timing. If you run a MSD BTM, you can add base timing easily without the worry of detonation because the BTM starts pulling out timing as soon as it see's any boost at all. Where you don't actually need to pull timing until 4psi or so depending. This will improve your overall ignition curve as well once the BTM starts pulling out timing.

WD

[FabroKA]

thank you WDracing thats what i was tring to say, and i read the same article you did i think about the single cam motors development fair lady Z and 510. the E comes from the same guys

[WDRacing]

No worries brah