throttle body coolant bye-pass

grumpyvette

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Staff member
if youve got a third generation camaro visit their site!

http://www.thirdgen.org/coolantbypass


http://www.ws6.com/mod-8.htm

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Here, the dyno shows a 6.3 horsepower and 7.1 ft/lbs torque difference between having coolant run through the throttle body and bypassing it, with an average gain of 5.6 horsepower and 6.8 ft/lbs torque. I made the first test after driving the car for approximately 15 minutes. I monitored Coolant Temp and Intake Air Temp while making the run. At the beginning of the baseline run, the coolant was at 178F, intake air was at 80F, and the throttle body itself had a surface temperature of 102F. After bypassing, I again brought the car to temperature and repeated the test. This time, the coolant was at 180F, intake air was 80F and the throttle body was at 82F. To make sure the runs were accurate, I set the cruise on the dyno to 70mph in 6th and let the car run for about 6 minutes. After this time, the throttle body had reached 100F. I let the car cool to 185F coolant temp, and 88F intake air temp. Running the car again with these elevated heat readings yielded another .2 horsepower and -.2 ft/lbs torque compared to before heat soaking the engine. Check out the Dynojet Race Routine between the stock vehicle, the stock throttle body coolant routing and bypassing the throttle body coolant.



By IROCZDave(iroczdave@aol.com)

This procedure is considered a "free modification."
After doing this myself on my engine (88' 350 TPI) I noticed a difference in the throttle response right away, as far as horsepower, well I've heard you may get 5 additional HP out of this.

From what I have read GM incorporated this into the throttle body to prevent any kind of freezing of the TB valve in extreme cold conditions by having water from the cooling system run through it.

This heats up the throttle body quite a bit (just try touching the "Tuned Port Injection" plate after a long drive) and from what I understand there is a possibility that the incoming air may be warmed slightly.

You want the air going into your intake system as cool as possible I've heard, cooler air has more density, that's all I know.

There are two ways to do this, both have the same results, I will cover both in this article and you can decide which is to your liking.

NOTE: If you live in an area where extreme cold conditions exist I would not recommend this procedure.

coolantbypass.gif


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The above diagram shows the "quick" method using a hard tube (approx. 5\8") to connect the existing hoses using clamps.

This takes little time to do, however if you are a stickler for details as I am this looks like a quicky job.

http://www.circletrack.com/enginetech/c ... index.html

I simply got a new piece of 5/8" hose with a built in (90 degree) elbow, and ran it from the black plastic heater control valve/diverter and down to the intake manifold outlet this took about 10" of hose to do and looks much better!
NOTE: Place the elbow end of the new hose at the intake outlet.

Now after you have everything back togther take you car out for nice long drive and when you get back, open the hood and feel the TB, it's cool to the touch!

hosebarb.jpg


THESE ARE AVAILABLE IN THE PLUMBING SECTION OF HOME DEPOT FOR UNDER $4
always measure carefully before you buy parts to be certain but you generally need a double 5/8" hose barb

http://www.discounthydraulichose.com/pr ... 178-xx.htm
You can leave the water outlets on the TB open if you wish, or do what I did!

I got some new 5/8" hose and from the left side TB water outlet ran the hose over past the battery through the fender and down under the battery tray , attached a small pickup funnel to the end of the hose and mounted it to the fender support bracket facing forward for maximum air pick up.

Then another piece of 5\8" hose from the right side TB water outlet ran next to the upper radiator hose, down next to the radiator and under the car, pointing rearward.

What this does basically is "air cools" the TB housing while your driving, I don't have the air volume specs if there is any to take in the first place, it's just an idea I had and I decided to try it.

watercavitiy2.jpg

TBcoolmod.jpg

keep in mind with some aftermarket efi intakes the throttle body coolant component of the IAC throttle body housing must be removed to allow the t-stat housing to fit
 
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Re: tb coolant bye-pass

BTW while were discussing engine mods.....
many guys notice that the stock aluminum corvette TPI heads dO NOT HAVE an exhaust cross over
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but some aftermarket heads do, and they worry that the extra heat will hurt performance, well ,in cold areas both the heat from the exhaust in the lower runners and the throttle body coolant passage heating the plenum tend to help low rpm fuel atomization ,that tends to help drive-ability and mileage.
AFR4.jpg

it won,t cause any problems at all. many TPI intake bases have the matching port that allows the exhaust heat to warm the lower intake runners during cool weather, but the upper runners flow air at about 200feet per second, plus at high rpms so theres hardly time to absorb much heat from runner walls at higher rpms
portedbase.jpg

but if you block off the exhaust cross over and modify the throttle body so hot coolant no longer flow thru them its worth several extra horsepower , as the engine gets a cooler and denser fuel/air mixture into the cylinders, but at the cost of a longer wait for the engine to reach operational temps and a bit less drive-ability until the engine reaches normal operational coolant temps near 190F-200F
the stock chevy L98 roller cam is a very poor choice when upgrading the performance on an early L98 ! and the stock heads and intake manifold are a HUGE restriction to making more hp.
youll also notice true performance intakes like the HOLLEY stealth ram, and most single plane performance intakes don,t have a cross over to heat the runners

Id talk to both CRANE and crower

CRANE 1-386-258-6174 Tech Line

crower 1- 619-422-1191

a cam similar to these makes a better choice

http://www.crower.com/misc/cam_spec/cam ... &x=41&y=10

http://www.cranecams.com/?show=browsePa ... vl=2&prt=5

other mods

http://www.lbfun.com/warehouse/tech_inf ... ooling.pdf

http://www.ws6.com/mycar.htm

http://www.eecis.udel.edu/~davis/z28/ecm_swap/

http://www.thirdgen.org/newdesign/tech/tpimod1.shtml

http://www.thirdgen.org/newdesign/tech/ ... pass.shtml

http://www.thirdgen.org/newdesign/tech/ednitrous.shtml

http://store.summitracing.com/default.a ... &x=23&y=12
 
Re: tb coolant bye-pass

you may want to do a bit of research on TPI intakes and options, the stock TPI was designed to maximize torque on a 305 SBC displacement and the port cross section is very restrictive, and theres not much material for extensive porting
if you want to start with a better casting the EDELBROCK BASE and ANY OF SEVERAL AFTERMARKET HIGH FLOW RUNNERS HAS POTENTIAL
PDRM0377L.jpg


stock vs high flow ports
the High-Flo TPI intake has larger runner (round) and intake (rectangular) ports than the stock TPI intake base, BUT still can be ported for larger/better air flow. Casting bumps, etc. should be removed. Some measurements are:

Stock Base runner ports = 39mm diameter (1195 sq mm) (1.470", 1.697 sq in ) *Measured
Stock Base intake ports = 29mm X 44mm (w X h) (1276 sq mm) (1.73"x1.15", 1.986 sq in ) *Measured

Edelbrock Base runner ports = 41mm diameter (1320 sq mm) (1.609", 2.033 sq in) *Measured
Edelbrock intake ports = 29mm X 48mm (w X h) (1392 sq mm) (1.883"x1.13", 2.138 sq in) *Measured

Ported Edelbrock Base runner ports = 45mm diameter (1590 sq mm) (1.757", 2.425 sq in) *Measured
Ported Edelbrock intake ports = 32mm X 52mm (w X h) (1664 sq mm) (1.26x2.05", 2.583 sq in) *Measured

ZZ4 (Vette L98) intake ports = 31mm X 49mm (w X h) (1519 sq mm) (1.220"x1.929", 2.353 sq in) *Measured

The Edelbrock base has some "gotcha"s that you should be aware of...

One is that some of the runner bolt-holes have been known to penetrate the water jacket. Its best to check your install with a water-filled coolant system before installing the runners. Use a quality thread-sealant on any bolts that are used in these "leaky" bolt-holes..

Second, the intake has many options for use on various F-bodys and Vettes.. You will have to block off one of the two EGR ports, depending on your application. Use a high-temp gasket maker to seal the unused EGR port blockoff plate.

Finally, there is a sensor port back near the distributor hole that is also into the water-jacket. Fbodys don't use this port and it must be blocked off with a 3/8"x24 NPT plug and sealant.

Both the vette EGR block off and the 3/8 NPT sensor hole can be seen in here

tpi1.jpg



tpi4.jpg

tpi5.jpg


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tpi4h.jpg

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read these threads, as usually a great deal of infos in the related threads

viewtopic.php?f=55&t=823&p=1214#p1214

viewtopic.php?f=55&t=1509

viewtopic.php?f=55&t=1745

viewtopic.php?f=55&t=1202

viewtopic.php?f=52&t=462&p=11960&hilit=porting#p11960

viewtopic.php?f=52&t=3143&hilit=shrouding

viewtopic.php?f=52&t=2630&p=6788&hilit=shrouding#p6788
 
The heated tb does serve more than one purpose, it actually is said to increase part throttle response, mpg and reduce emissions. These at the expense of moderate to full throttle power.
 
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