I saw a kit to bypass the throttle body/coolant passage....are there any real performance benefits to doing this? Why is it there in the first place?

Flash :flag

 

the factory puts it there to prevent icing in cold,damp weather.i've heard there is no real gain in bypassing it.i haven't seen anybody report any gains on the dyno.i can't see where it could hurt though.

 

No horsepower gains; bypassing the throttle body just improves throttle response (at least I'm pretty sure on this).

Matt

 

I doubt if there is any real benefit to power, and increased throttle response is just a myth. You're better off leaving it be to prevent throttle icing, especially if your climate. Cool damp winter/spring conditions in So Cal are perfect conditions for throttle icing.

Duke

 

It is one of those "can't hurt" sort of things. I think the air spends SO little time in the TB that it really doesn't matter. :)

 

It prevents you from losing power as the engine gets hot. It does not increase power.

 

I have the kit but I don't think I'll install it. All it takes is for the throttle to stick open one time to total your car. I would do it in my LT-1 Z28, but the composite intake on the LS6 doesn't transfer heat to the throttle body. Increases the chance of icing.

Jeremy :seeya

 

Well, let your climate be your guide. If you drive in potentially freezing conditions (brrrrrr!), then don't do it.

I live in Central Florida so I have no fear about "icing up" the throttle body. It might not noticably help increase power, but I for one prefer lower intake and engine temps however I can get it, especially on easy, low-buck mods like this one.

 

Not so! Idle and low speed when the thottle is near closed is when you are most prone to get ice due to the large pressure and temperature drop past the throttle blade. At WOT the air passes through the throttle body so fast it's not heated up. Net benefit of bypassing the throttle body coolant line is therefore more likely to be negative than positive.

Light airplanes have a "carburetor heat" **** that you pull every time you back off the throttle to low revs or idle for decent. This runs the carb inlet air through an exhaust manifold heater to prevent carburetor icing. They use this system since the engines are air cooled. The worse conditions for carburetor icing are temperatures of about 30 to 50 degrees with high humidity.

As mentioned in an earlier post, the composite manifold is a good thermal insulator, so engine heat is not readily transferred to the throttle body to keep it from icing up. That's why GM installed the throttle body heater line. Believe it or not, GM engineers actually know more than most of the amateur rocket scientists on this board.


Duke




[Modified by SWCDuke, 12:15 PM 4/29/2002]

 

Believe it or not, GM engineers actually know more than most of the amateur rocket scientists on this board.

It also helps with keeping the TB clean, they can get gummy if you bypass, just ask EVERY 5.0 Mustanger.


[Modified by SWCDuke, 12:15 PM 4/29/2002][/QUOTE]

 

Very true, but some things they do are for mass production reasons that protect GM and their products. They are very smart, but it is well proven that a cold air intake and tube headers will pick up 20 - 25 rwhp. So if they are so smart, why don't they put them on at the factory? They obviously have downsides, but many owners are willing to accept the down side as long as the engine is not going to be hurt in the transformation, under the driving conditions that the owner knows he is going to be operating.

 

The earlier intakes had a restictive inlet, but it's debatable if an aftermarket intake and/or air filter makes more peak power (outside the range of dynamometer accuracy/repeatabilty,which is about two to three percent) than the '02 intake and paper filter. As far as headers are concerned, if properly designed they will make more power, but are not emission legal. Depending on your state, you might get away with them, but probably not in California. Everything up to the converters is considered part of the emission control system.

The big issue in emission certification today is catalyst and O2 sensor lightoff since about 80 percent of total emissions generated during the certification test are produced in the first couple of minutes until the O2 sensor and catalyst are hot enough to function as designed. The exhaust system is designed with heat retention and minimal thermal mass in mind. Headers radiate a lot of heat because there is a lot more hot surface area, so they might bust the certification test due to slower warmup of the O2 sensor and catalyst, and many have found that they create other problems, like boiling the clutch hydraulic fluid.

There are many government and corporate standards that designers and engineers must meet, but with today's technology, they are able to optimize the car quite highly, and there are few compromises that have to be made. Bottom line: It's tough to "improve" on the basic car without suffering some other consequenses or spending a very large sum of money for a signficant increase in power output.

You can get at least as much power increase that headers yield with a set of reworked heads. The torque/power increase will be across a broader range, which means more average power through the operating range. The benefit of headers is limited because of the mild valve overlap. When you design an engine to use headers, particularly if you can run open exhaust, you set up the valve timing with a lot more overlap, and if you have optimized the design there are substantial benefits, but the benefits of headers are limited on street engines because of their mild valve overlap and the exhaust backpressure inherent in even the best street legal exhaust systems.

Duke



[Modified by SWCDuke, 4:17 PM 4/29/2002]

 

SWCDUKE, Thay had the coolent going through the throtle body on my l98 90 vette with an aluminum manifold also. I don't think it helps as much as it used to now that it's composit for performance, but since the throtle body stays much cooler now than thay used to, I am not comfortable leaving it bypassed in the winter month's. 10min and pliers to put it back to stock in oct. Ric