Butterfly plate mod?

[HIM]

Idk if this is an actual mod or not but I heard something like modifieing the butterfly plate on the intake system to gain something like 5 horse. Is this a legit mod or some bull**** and if so how do I go about doing thi mod?

[LEADFOOT]

There ar a few posts on this mod in this forum. The S10palnet 4.3L V6 forum. Go back a few months and check them out. Some say no gain, some say may hurt performance, some say go for it. A guy I met at a self serve carwash with a s10 told me to do it so I did without asking anyone first and didn't notice that big of a gain or loss. I'm sure the more mods you do like intake and exhaust doing the mod could be beneficial. Have you looked down in there yet to see what people are talking about?

[Sparky2263]

An old (but still very good) mod on butterflies and throttle shafts is thinning to gain airflow. They offer thin plates, shafts and screws for carbs. Don't know if they do for T.B's but any good machinist can work wonders there.

As far as power increase, well, if you can use the extra airflow, you'll get a power increase.

[LEADFOOT]

Check out http://www.cfm-tech.com they have a new butterfly you can buy. I think it is a rip off because all you have to do is remove the throttle body, drill out the rivets, the diffuser will fall off then put rivets back in the holes. But by checking out their site you can see the difference.

[LEADFOOT]

Sparky, what do you think of the cfm-tech TB with it bored out to 75mm. Do you knoiw what the stock bore is? I'm sure you know about cfm-tech. If not check out their site in my last post and let me what you think.

[Sparky2263]

Well, interesting site. Never been there and saw a few things I haven't previously seen. Here's the deal though, if you don't need the addl. airflow, it's not gonna do much good. How do you know if you need more airflow? With the breather off, hook a vacuum gauge to manifold vacuum. If it reads more than 1/2" at WOT, you will benefit from more airflow. I use the MAP voltage to do the same thing. Found out how restrictive the stock airbox was when looking at my airflow requirements. Added a 1/2" just by installing it. Very restrictive.

[03 Rado]

Its 72mm stock, 75 bored out. 72 mm with the plate flows a litl;e over 400 CFM, with the plate out 490, 75mm flows just over 520. A 4.3 at 85% eff which is good needs 273CFM.
This same bore size, throttle body arrangement feds a 5.7 all the way up to a 8.1 liter. You think you need more??? Great gains to be had?
All your going to do is take away the sensitivity of your accelerator. Lets say at 2000 rpm you normally need the plate open 25%, now with this oversized bore only 15%. Now that dont sound to bad, does it? By WOT really you only need the throttle plate open just around 60% to get all the air it'll ever require! That doesnt sound bad does it?
NOW WHAT EVERYONE FAILS TO OPEN THERE GOD DAM EYES AT, is the fact the TPS see this too. Oh the 02's may pick up a leaner condition and adjust it, but 02's accuracy really isnt there so you'll end up to the lean side, but you'll be running timing maps based off the TPS which will br lower than if you left it alone!

[biglouie_underpressure]

Its 72mm stock, 75 bored out. 72 mm with the plate flows a litl;e over 400 CFM, with the plate out 490, 75mm flows just over 520. A 4.3 at 85% eff which is good needs 273CFM.
This same bore size, throttle body arrangement feds a 5.7 all the way up to a 8.1 liter. You think you need more??? Great gains to be had?
All your going to do is take away the sensitivity of your accelerator. Lets say at 2000 rpm you normally need the plate open 25%, now with this oversized bore only 15%. Now that dont sound to bad, does it? By WOT really you only need the throttle plate open just around 60% to get all the air it'll ever require! That doesnt sound bad does it?
NOW WHAT EVERYONE FAILS TO OPEN THERE GOD DAM EYES AT, is the fact the TPS see this too. Oh the 02's may pick up a leaner condition and adjust it, but 02's accuracy really isnt there so you'll end up to the lean side, but you'll be running timing maps based off the TPS which will br lower than if you left it alone!
well that shot down my idea for a 2000 cfm tb.j/k what's really funny is when ppl try to force huge tb's.

[jharrison]

It can be done in about an hour. Just remove your TB, then remove the butterfly via the two screws and slide it out. Cut the restrictor off with a dremel or similar tool, smooth the edges after you remove it. Then reinstall, and I highly recomment using the blue loctite on the two screws, but you dont have to. Also I wouldn't cut it completely off unless you have already done the EGR mod.

[Supercharged-ZQ8]

TB mod = decent mod (for free) -- but you won't notice anything major, but every single hp counts in many cases. As jharrison stated, don't cut the diffuser off entirely unless you have an EGR limiter in place. Combined, you might see about 2-7 hp with both in place -- not phenomenal, but what can you expect for free?

I've got both in place, myself. Did I notice much of a difference? Not really. I already had the big power mods in place before doing them -- but, as I said before, every hp counts!

[Supercharged-ZQ8]

A larger TB is a waste of money in most cases. For the S-Series, as 03 Rado stated, the TB can provide MORE than enough flow for a well-modded 4.3L. Not really, in my opinion, a worthwhile mod.

[LEADFOOT]

What about my truck that doesn't have an egr.

[Supercharged-ZQ8]

Yours DOES have an EGR -- it just may not be external. Instead of an external valve and inlet tube, it's all internalized.

If you have no way of limiting the EGR, you can still do the TB diffuser mod -- you don't want to cut the diffuser off completely, though. Keep the same basic contour/shape, but trim the diffuser down to HALF its original size. The diffuser is meant to funnel air back towards the rear cylinders by deflecting air away from the front cylinders (to avoid a lean condition in those front two cylinders). By cutting it down to half its size, it is still there doing what it was designed to do, but is not causing as much of an obstruction in the air flow. The reason it is meant to deflect the air flow from the front cylinders (1 & 2, that is) is because with the EGR going into those cylinders, they would go too lean without it.

So, if you don't have a way of limiting the EGR (because you don't have the external apparati to do so), just cut it to half its size and you'll be fine.

[biglouie_underpressure]

Yours DOES have an EGR -- it just may not be external. Instead of an external valve and inlet tube, it's all internalized.

If you have no way of limiting the EGR, you can still do the TB diffuser mod -- you don't want to cut the diffuser off completely, though. Keep the same basic contour/shape, but trim the diffuser down to HALF its original size. The diffuser is meant to funnel air back towards the rear cylinders by deflecting air away from the front cylinders (to avoid a lean condition in those front two cylinders). By cutting it down to half its size, it is still there doing what it was designed to do, but is not causing as much of an obstruction in the air flow. The reason it is meant to deflect the air flow from the front cylinders (1 & 2, that is) is because with the EGR going into those cylinders, they would go too lean without it.

So, if you don't have a way of limiting the EGR (because you don't have the external apparati to do so), just cut it to half its size and you'll be fine.i thought i was the only one that knew that.

[Hammer]

from what i understand, the new egr setups (internal) are much better than the external setups, no pintel no clogging, etc and you really don't need to do anything to them. I thought the diffusor was also to direct air to the back cylinders where they would naturally run lean because of location of the tb and injectors?

I'm just not been persuaded that the egr mod is any good on the internal setups and that the tb mod is worth it. I know people say the throttle response is better, but mine is so good now it's hard ease into the gas.

thats just my opinion on it and i could be totally wrong.

[badasS10]

what hapens if you removed the diffuser without reinstalling the rivets, and doing the egr mod? I have a 97' 4.3 , and i noticed a little increase in get up n' go, but now my truck idles at around 10 mph. I **** you not, 10 mph! why is this happening? any response is appreciated.

[j894]

Your supposed to leave the rivets in.
Now air is leaking past the throttle plate & making it idle higher.
I guess you can get some pop-rivets & put them in to block the holes?

[04silveradomykk]

Holey old thread batman!

I tried the mod on my truck, but it didn't react very well. And my throttle body spacer stopped whistling....I couldn't have that. So I put the plate back on.... I think I'll try cutting it down.

[Mikz86TA]

I did the CFM-Tech part due to warranty on truck. If I needed to swap it back on, it was a 2 min job. I noticed more response especially at cruzing speed on interstate. It also helped the off-line accel a little, but not significantly by itself. I did a K&N FIPK and noticed a gain there too throughout the whole RPM band. I swapped the TB blade back on with the K&N installed. I noticed the off-line was about the same as B4, and noticed I lost the cruzing punch I had with the CFM-Tech blade. You can drill and JB weld it, but I just didnt trust it to stay forever. Also if you clump it on then it might impede a little airflow. But thats opinions and fears.