CamaroX84

I've seen it in people's sigs, but what is a TB coolent bypass? How do you do it? Is it beneficial? ANY help would be greatly appreciated. Thanks.

Ski89Z28

CamaroX84,
The TB (Throttle Body) coolent bypass is one of those free mods you can do. This site has a tech articles that you should read to find out cheap and easy mods you can do to your car and get a few extra HP.
In this "tech articles" they tell about the TB coolent bypass click on this: https://www.thirdgen.org/newdesign/t...ntbypass.shtml

Some say doing this will lower the air temp coming in an therefore, cooler air is denser and more air in the cylinder chamber hence more HP. Others will say in very cold climates it could cause moisture to freeze up in the TB. But I read threads on this from guys in Canada and they had NO problem. So go figure.
I did it but after I got my time at the track so next spring I'll go again and see what happens. Did I fell more power? Maybe but very little but the more mods the more these little mods help give you more HP.
Hope it helps.
Good Luck




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89 IROC 350 Auto
Custom DUAL Exhaust
Edelbrock Performer 6085 Aluminum Heads
ZZ9 Cam
TPIS Level 5 Chip
14.01 @ 97.0mph with 2.77's gears and a bad ignition control module!
And Free mods.

Grim Reaper

As Ski said, the intent of bypassing coolant from flowing throw the TB is to make the incoming air charge cooler. For every 10*F drop in the intake temperature there is a 1% increase in HP. That is why guys will get quicker times during the spring or fall than in the summer.

The benefit of coolant flowing through the TB in cooler climates is to prevent icing of the TB in cold climates. I personally have never experienced this and I have driven around when the temperature has dropped to 0*F. But there are couple of other reasons besides this.

If the temperature of the MAT remains below -40*F for more than 5 minutes, it will trigger an SES code. The GM eprom cannot handle any temperature below this. In extreme colld, this will heat the temperature enough to avoid this from occurring.

Another reason is that the EGR ceases to function if the MAT goes below 5*C (about 41*F). It takes about -10*C (15*F) for this to occur with the TB bypassed on a hot engine as the EGR does warm the plenum itself. Below that, the EGR stops functioning and the plenum will "super cool" to the ambient air temperature.

Lastly, I have done a variety of tests with the MAT and I find that the GM eprom calculates the adjustmet to the injector pulse width by the difference between the MAT and CTS. With the TB connected as GM intended, on a fully warmed engine, this difference is not that great and the GM eprom will adjust the injector pulse width correctly. But with the TB bypassed, the difference causes the GM eprom to overcompensate as this is not how GM intended it to function. The eprom thinks that when the difference is great that the engine has just been started and that while the coolant is at the intended temperature, the block itself is still heating up...so the ecm adds more fuel as it thinks it is still warming up.

The net result that for every 10*F, instead of adding about 1% more fuel, the ecm actually adds about 2.5%. This results in running way too rich in colder climates. This is why many people will complain that their car appears to burn more gas during winter...and often they have a hot t-stat, but the TB is bypassed.

So if you want to use this mod in a colder climate, you either have to reduce the fuel pressure or shorten the pulse width to get the correct amount of fuel. The temperature only has to drop to 40*F for this over compensating to occur.

CamaroX84

Thanks for all the info. So, then, with this in mind, is it even worth it? Thanks.

theformula

Is it worth it? Who knows. After talking to Glenn, I'm seriously considering re-routing the heater hose through the TB again. The computer relies on certain factors to make it's calculations correctly..I sure as hell don't want to screw that up.

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91 Formula
305 TPI 5speed
1LE/G92/WS6
Cold air ind. w/K&N, SLP airfoil, ported/polished plenum, March pulleys, TB coolant bypass,Crane AFPR(43psi),Crane Gold 1.6rrs,MSD coil,MSD6AL, Holley 9mm wires, fastchip, Bosch O2sensor, SLP headers & catback,short shifter,3:73s w/Auburn posi,160* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

GMTech

I have done it to my car, and really don't experience any problems. As for the difference in MAT and CTS, there are alot of variables involved.

If you want to do it, here is what I consider the "ultimate" bypass. Please note, this is permanent. TB Bypass

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Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
-->14.97 @ 94.9 MPH<--

'97 Bonneville SSE

[This message has been edited by GMTech (edited January 21, 2001).]

85F-body

i have a 1985 camaro and you name syas 84 and i don't think that they made a tpi in an 84 camaro but any way you can get a small amount hp out of a free mod i say do it you can't ever have enough power i just got a 10" anti freeze hose and disconnected the hoses completly and made it come from the vent to the intake manifold it only adds like 1% like that other guy said cause it is a free mod

JoelOl75

I did this mod not by choice but by necessity. The new TB usits don't come with the coolant/IAC plate and mine broke trying to get it off, luckily just the coolant part broke off. I had no probs without coolant flow and its cold here.