C4 bypass surgery
Thread Starter
Intermediate
Joined: Sep 2013
Posts: 49
Likes: 3
From: TEMECULA CA
C4 bypass surgery
Hello All,
On the '88 C4 i have in SoCal I discovered that the heater was bypassed, which is fine with me, but I have also been told since I live in a consistently warm climate I can bypass the TB too.
Any issues with bypassing both the heater and TB?
Anything to be concerned about w/TB if I get into cold weather?
Are there any performance gains?
C4 awesomeness!
On the '88 C4 i have in SoCal I discovered that the heater was bypassed, which is fine with me, but I have also been told since I live in a consistently warm climate I can bypass the TB too.
Any issues with bypassing both the heater and TB?
Anything to be concerned about w/TB if I get into cold weather?
Are there any performance gains?
C4 awesomeness!
Le Mans Master
Joined: Jul 2004
Posts: 6,228
Likes: 698
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Hello All,
On the '88 C4 i have in SoCal I discovered that the heater was bypassed, which is fine with me, but I have also been told since I live in a consistently warm climate I can bypass the TB too.
Any issues with bypassing both the heater and TB?
Anything to be concerned about w/TB if I get into cold weather?
Are there any performance gains?
C4 awesomeness!
On the '88 C4 i have in SoCal I discovered that the heater was bypassed, which is fine with me, but I have also been told since I live in a consistently warm climate I can bypass the TB too.
Any issues with bypassing both the heater and TB?
Anything to be concerned about w/TB if I get into cold weather?
Are there any performance gains?
C4 awesomeness!
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
If you've never driven a car without a heater, you'll hate yourself if your ever stuck in the cold.
If I was to buy a C4 with the heater bypassed, I'd take $1000 off the price.
Instructor
Joined: Oct 2008
Posts: 193
Likes: 19
From: Stevenston, Scotland, GB
More power and better running is a combination of all these tricks. I have:
1. TB coolant bypassed
2. TB airfoil
3. Smooth TB/MAF tube
4. Descreened MAF
5. Relocated MAT sensor
6. AC delete
7. A.I.R. delete
8. Open air box
9. itg free-flow filter
10. 60mm dual exhaust with no boxes or cats
11. Fuel/ignition totally refurbed end to end
12. About 150lbs of dead weight removed.
Just backyard tinkering for me, but my '87 does run very well as I suspect, due to the combination of all these items, but not any single one.
1. TB coolant bypassed
2. TB airfoil
3. Smooth TB/MAF tube
4. Descreened MAF
5. Relocated MAT sensor
6. AC delete
7. A.I.R. delete
8. Open air box
9. itg free-flow filter
10. 60mm dual exhaust with no boxes or cats
11. Fuel/ignition totally refurbed end to end
12. About 150lbs of dead weight removed.
Just backyard tinkering for me, but my '87 does run very well as I suspect, due to the combination of all these items, but not any single one.
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Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
The throttle body coolant bypass isn't usually done for added hp, it's done to make it easier when the engine needs to be worked on...With it bypassed you don't need to worry with coolant leaking when removing the TB... As far as bypassing the TB causing any problems in cold weather, it would have to get very very cold for it to affect the car , and unless you live in Alaskan type weather I don't think you will have a problem....
....WW
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....WW.
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Last edited by WW7; Apr 27, 2016 at 06:25 AM.
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
Hello All,
On the '88 C4 i have in SoCal I discovered that the heater was bypassed, which is fine with me, but I have also been told since I live in a consistently warm climate I can bypass the TB too.
Any issues with bypassing both the heater and TB?
Anything to be concerned about w/TB if I get into cold weather?
Are there any performance gains?
C4 awesomeness!
On the '88 C4 i have in SoCal I discovered that the heater was bypassed, which is fine with me, but I have also been told since I live in a consistently warm climate I can bypass the TB too.
Any issues with bypassing both the heater and TB?
Anything to be concerned about w/TB if I get into cold weather?
Are there any performance gains?
C4 awesomeness!
Make sure you post back what your experience is if you do it.
Team Owner
Joined: Aug 2005
Posts: 34,988
Likes: 515
From: Riverside County Southern California
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
2017 C4 of Year
2016 C7 of Year Finalist
St. Jude Donor '09 thru '20
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
When it comes to drag race competition, nobody would argue against bypassing the tB - the theory being "every little bit helps"!.
Icing...is the issue the heat is intended to prevent. And, it doesn't have to be below freezing either - humidity, e.g., a cold foggy morning, plays a huge role in concert with low temperature.
So, it is a trade-off between benefit and liability. What practical benefit is gained, and at what cost in terms of detriment.
The ONLY time air density (DA) is a factor in total engine output is at WOT; less than WOT and the motors output is controlled by throttle opening %. And, at WOT, air velocity past the TB (and that includes runners too) is such that there is very little time for heat transfer and therefore little if any practical change in DA occurs as air rushes past the TB.
I live in northern IL, my TB is bypassed, and I occasionally drive in sub-freezing temps, and have had NO issues with TB freeze-up. But, I must add that it was on clear, dry (air) days, i.e., not humid or foggy, etc.
My reasons for bypassing were two:
I bypassed my TB for those reason (above), but did not expect or detect any difference in WOT performance, what-so-ever.
If someone wrote about a 5-6 hp gain (on an L98 especially) after bypassing the TB, I'd want to see the data before accepting it on face value.
Icing...is the issue the heat is intended to prevent. And, it doesn't have to be below freezing either - humidity, e.g., a cold foggy morning, plays a huge role in concert with low temperature.
So, it is a trade-off between benefit and liability. What practical benefit is gained, and at what cost in terms of detriment.
The ONLY time air density (DA) is a factor in total engine output is at WOT; less than WOT and the motors output is controlled by throttle opening %. And, at WOT, air velocity past the TB (and that includes runners too) is such that there is very little time for heat transfer and therefore little if any practical change in DA occurs as air rushes past the TB.
I live in northern IL, my TB is bypassed, and I occasionally drive in sub-freezing temps, and have had NO issues with TB freeze-up. But, I must add that it was on clear, dry (air) days, i.e., not humid or foggy, etc.
My reasons for bypassing were two:
- I no longer have to drain some coolant to remove the plenum
- The main reason is the ignition module is heat-sinked to the plenum and the plenum temperature runs significantly cooler w/ the TB coolant bypassed.
If someone wrote about a 5-6 hp gain (on an L98 especially) after bypassing the TB, I'd want to see the data before accepting it on face value.