Big Bore Throttle Body - Part 2

[82-T/A]

Hey guys,

I just wanted to revisit this quickly. I'm pretty close to getting the big bore throttle body, but before I spend the money I wanted to hear from some of the people who already have it. What kind of performance gains did you see? Specifically, I'm guessing that you saw an improvement in mid to upper rpm power, right? One thing I'm concerned with though is the low-end. Off the line, what kind of power improvement did you see? Or... did you LOSE low-end power?

Physics and flow being what they are, it would make sense to me that the velocity of the incoming air would be less in the lower rpms and probably hurt the off-idle performance... although, if it makes up significantly in the upper rpms, that might make it worth it.


Thanks guys!!!

[Bruce]

The response becomes very quick and I believe much faster off the line with the throttle body.

Add a CAI and dual exhaust and you will really notice some difference.

[82-T/A]

Originally Posted by Bruce

The response becomes very quick and I believe much faster off the line with the throttle body.

Add a CAI and dual exhaust and you will really notice some difference.

Thanks! I appreciate the response. I already have the Clear Image Header, Hi-Flow Cat, and the GM Cold Air Intake.

I figured the larger throttle body might be the next step.


Thanks!!!!

[cerberus]

Welcome to the other side There's a few folks here who replaced their throttle bodies. Looks like they're out havin fun or something right now. I dont' want to just say "use the search", but there's posts out there with reports. Generally good responses if I recall correctly.

SMS Big Bore Throttle Body

Big Bore Throttle Body

and probably more...

[Gerry]

Since the throttle body meters only air, a larger body will allow more airflow where the engine can use it. Going way too big, like say a 1000cfm body, means that you will have an overly sensitive throttle (very big response for a small throttle input) and some difficulty correlating the throttle position sensor to air flow. It's not a huge problem in mass airflow systems. You're also bleeding some old technology over in what you're heard. On a carbureted engine, having too large a venturi area for the airflow needs of an engine makes for lazy boosters, which does affect low rpm behavior. Obviously not the case here.

I've never seen the flow numbers for the intake so I can't say that you have a flow restriction in the TB. It's certainly possible to put on a larger TB and see no improvements if there is no restriction there. An easy way to test this is to hook a vacuum gauge to the intake and do a heavy-load full-throttle accelleration run. Have someone else monitor the gauge. At your horsepower peak, you should see a vacuum reading no higher than 1.5"hg. Higher than that and you have a restriction in either the TB or the air intake.

Of course, you could just get the big bore TB and test it with the ol' butt dyno.

[seal9]

I have the Clear shorty, H/F Cat, and KS1 with the SMS T/B what I experienced was a smoother acceleration but not really more power...I don't think there will be a HP change just smoother acceleration....Seal9