HAVE 94 CAMARO LT1. WITH A 58 THROTTLE BODY, K&N AIRFILTER PACK KIT, MARCH PULLEYS, HYPERTECH PROGRAMMER AND 160 THERMO, HEADERS, 410 GEARS, WHAT SIZE OF INJECTORS SHOULD I UPGRADE TO. I WANT TO PUT THE BIGGEST SIZE ON MY CAR TO FIT THIS APPLICATION? - MIKE

 

stock injectors are fine for your application. when you go heads/cam you might need to upgrade then.

 

You seem to subscribe to the "bigger is better" approach to mod'ing your car. Not necessarily the best way to go. Just using a 58mm TB on a relatively stock setup is questionable - I've seen at least one dyno test where a 58mm lost 10HP compared to the stock TB.

Stock injectors will easily support 400HP, and you aren't quite there yet. There is no benefit to going to a larger injector than you need. And, you would need PCM tuning to accomodate the larger injectors.

 

I DONT KNOW WHY YOU WOULD THINK A LARGER THROTTLE BODY WOULD DECREASE HORSPOWER. THE MORE AIR - MORE HORSPOWER. WHAT DO YOU THINK SUPERCHARGERS DO???

 

Are you serious?

 

detroit1994z28 turn your caps lock off, its annoying.

bigger isnt always better

stock injectors will work fine with your application.....

look for power elsewhere, maybe a cam?

jesse

 

You can open the door wider all you want but the hallway is only so big. Blower is different. We're forcing air through the door and into the hallway. Stock motor doesn't need a 58mm and probably hurts velocity.

 

YOU PROBABLY DIDN'T PORT MATCH YOUR INTAKE FOR THE 58MM TB EITHER. IT IS DYNO PROVEN THAT A 58 MM TB ON A STOCK ENGINE IS NOT GOING TO PRODUCE GAINS, AND WILL MOST LIKELY HURT YOU LIKE ALREADY STATED.

Oh yeah, and turn the caps off.

 

Hahaha, he doesn't know Fred very well does he?

 

Let me try and help you over the misperception that simply enlarging a component will increase air flow. The engine air flow is determined by three things.... displacement, RPM and volumetric efficiency. You can only increase air flow by changing one of those three. Changing a RESTRICTIVE inlet track component has the possibility of increasing volumetric efficiency. But if the component is not a significant restriction (read that "pressure drop") to air flow, making it bigger isn't going to have an appreciable effect on volumetric efficiency.

I always like to give a real world example for the non-believers.... my 381ci stroker redlines at 7,400RPM. It is breathing through a very healthy set of ported LT4 heads .... close to 300cfm at 0.700" lift, and a mild solid roller cam with a shade under 0.600" lift. The engine breathes through a Holley 58mm throttle body. The air demand on this engine is going to be quite a bit higher than a relatively stock 350ci engine.

In tuning this engine on an engine dyno, where it is possible to measure variable like air and fuel flow, we found that engine air flow reached its maximum at only 77% throttle opening.... opening the blades further did not materially increase air flow. The 58mm TB was not a restriction. In fact, if you do the math, a 52mm TB would be all that I really need for my setup.

How could an oversize TB "hurt" performance..... the programming uses a variety of inputs to detemine the wide open throttle (WOT) A/F ratio.... also known as power enrichment, or "PE" mode. Things like throttle position, the rate ar which the throttle is opening, MAP and airflow from the MAF are all taken into consideration, in one way or another to set the target A/F ratio and to find the operating point on the ignition timing maps. Alter one of those inputs - e.g. thorttle position - to the point where it no longer represents the true airflow potential of the system, and the PCM gets thrown "off".... a smaller diplacement in throttle movement is causing a larger increase in air flow and hence MAP levels, to the extent the PCM is being mislead. This can cause a reduction of power production, if the PCM is not targetting the correct A/F ratio, and using the correct timing settings.

Again, my comment regarding loss of 10HP when a 58mm TB was installed on a (properly ported) intake, on a relatively stock engine was taken directly from a chassis dyno test run specifically to measure the possible gain or loss of using the large TB on a stock engine.

http://www.ws6zxr.com/showthread.php...+throttle+body

I also have a dyno chart of an application that put a 52mm TB on a "roughly" 300rwHP bolt-on motor, and the HP gain was 2.5, and torque increased by 3.2lb-ft. The area of the TB increased by more than 17%, but HP increased less than 1%.... so there goes the theory of "a bigger TB flowsa lot more air". Also note that GM saw fit to use the same 48mm TB on their 502 cubic inch, 502HP Ram Jet crate motor.

I'm not trying to bust your 'nads here.... I'm tryuing to help you spend your $$$$ in a location where it will produce the best HP gains.