Big Bore Throttle Body Question
 

The question is, what is the shift for each of these power wise in the RPM band?
I am looking for more low and mids, and there are two options here for a port job.

THE OPENING AT THE THROTTLE BODY BEGINS AT 69mm INSIDE DIAMETER....TAPER TO A 60mm BUTTERFLY.... THEN OUT TO 62mm TO MATCH THE INTAKE MANIFOLD OPENING.

THE OPENING AT THE THROTTLE BODY BEGINS AT 68mm INSIDE DIAMETER....TAPER TO A 61mm BUTTERFLY OPENING + HALF SHAFT MOD = 63mm CFM AIR FLOW.

Sorry about the all caps, I cut and pasted the ad.

is your intake manifold stock? Because just modifying your tb isn't going to change anything but your throttle response really. Maybe a few horses.

I was thinking about doing a little porting when it was all torn apart.

Just curious on any difference on how they ported the two TBs differently.

It will still effect the velocity build up

Original Poster, the larger the opening, the slower Velocity Build Up and the higher your powerband will shift. If you're near stock, there honestly is no reason to go with a larger throttle body. The size of your intake and exhaust system all revolve around the design of your camshafts (duration & lift) because it effects intake and exhaust velocity and consequently intake and exhaust resonating.

What kind of power are you trying to make overall?

This is for my wife's 03 Ecotec Sunfire.
I have had these things done:

K&N drop in filter
2 1/4" turbo muffler
2 1/4" piping all the way to the down-pipe
2 1/4" cat
2 1/2" resonator (went a hair larger because of the baffles)
Ground wire kit with (7) 8 guage wires

I want to get more lows and mids.

I also want to get the B&M Shift + kit soon along with a tranny cooler.

I am confused on what brand header to buy, as Tsudo and Pacesetter sounds like hit or miss. I do know I want a 4:2:1 header and 2 1/4 downpipe.

The intake side of the car I wanted to go with light mods.
I literally might match port and smoothen any burrs and use the tb to shift my powerband hopefully lower. I just worry about throwing a CEL due to lean conditions from going to wild with adding more air.

I never need to go over 80mph anyways, so the power up can come down and help the lows and mids.

Any other ideas on how to obtain that result?

Getting a bigger TB wont move your powerband lower, just higher. If you want low end, buy a long-tube header. :twothumbs

don't those have blowers available? i could very much be wrong though.

They should have a supercharger kit...

adam (njhk) has done a lot of modding to a sunfire... AND EVEN MORE RESEAECH!!! turbocharged it so hes a good one to ask about for that car atleast

get different grinded cams if you want lower... im not sure if they sale them but u can get blank cams n have them grinded.... dont know ur spending or time limit

I have a blown sunfire. Options for the 2.2 are endless, but you need to do more than attacking your tb with a dremel to 1. go lean lol and 2. to make power.

Bigger isn't always better. A larger tb with a stock manifold, head and cams isn't worth it. It's like wiring up a boost gauge with no boost. CHECK out patriot performance's site and or level zero motorsport's site. Ideal for cams.

Also bigger tb isn't for lows and mids. If you want lows and mids I'd suggest the tsudo. I have a weapon R header which is the same basic design. 4-2-1. Love it.

Thanks you guys for the input.

I guess I will keep the TB stock and just get that 4-2-1 header.

Has anyone gotten a lean code on their Sunfire 2.2 Ecotec with a CAI?

The only reason I ask is because so many have with their Cobalts.

I think for my Cobalt though I might just get the GM Performance intake, of which I know it is not much of a gain, but down the road I may add the hood scoop and have a small removable door so during the winter I can close it off so it wont run lean. I also want the touring model GM Performance exhaust and exhaust manifold. I do not want this car to look like I am tricking it out, nor sound like it. I hope that touring exhaust is pretty quite. The videos on YouTube make it hard to tell.

I might also run a ground wire kit on the Cobalt, and I do realize the battery is in the trunk . I have thought about it and I can go off the ground wire that leads into the engine compartment then stem it from there. I have had two cars so far that I have used ground wire kits and they did make a very positive difference in up and go and idle quality. A lot of people believe they do absolutely nothing, but that is fine as I am actually very surprised myself that it made such a difference both times. I thought the first time was because the car was old and the grounding was going bad due to age, but the 03 Sunfire had the same boost in responsiveness.

I have never used a voltage regulator though, has anyone here used one?