thermostat house interfers with boost bypass actuator (Page 1/2)
Charlie1963 AUG 29, 07:50 PM
Working on my 3800 swap modifying a stock v6 thermostat housing. I cut out the section with the small hose bibs and now trying to determine the correct orientation of the flange holes with the large coolant hose before welding the pieces back together. The problem is the boost bypass actuator vacuum line fitting is hitting the tstat housing.

I want to keep the bypass so is it possible to move the bypass actuator maybe by modifying the bracket? It would need to move about an inch maybe a little more to be out of the way.

The ECU has already been programmed to keep the bypass but how would the engine run if I remove the bypass without getting the program changed?

thanks
Tweeder AUG 29, 10:26 PM
I just used the thermostat housing that came on the 3800 and added a fill point there and the other end attaches to the fiero coolant system.

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86 SE Convertible 3800sc 4t65e HD.

olejoedad AUG 29, 10:58 PM
I've always used the 3800 t-stat housing with no issues.....fill the block, install the t-stat and housing and the hose. Use the bleeder to burp air from system and keep the coolant tank full....

[This message has been edited by olejoedad (edited 08-29-2014).]

Charlie1963 AUG 30, 03:06 PM
Thanks for the responses. I like the Fiero tstat housing for the ease of getting to the thermostat. Since I've already got the housing cut and ready to weld I'm going to try to move the boost valve out of the way by modifying it's bracket.
Lou6t4gto AUG 30, 03:39 PM
I'll be watching This. I've got a 2.8 housing ready to cut, but was Also wondering about the By pass valve.
Dennis LaGrua AUG 30, 06:20 PM
It is possible to cut and re-weld the thermostat housing to fit but keeping the BBV actuator in place requires very careful modifications. You can use the stock 3800 thermostat housing as Joe has said but you will need a high fill point to pour in the coolant . An easy solution is to use a Moroso inline fill housing with a 25lb cap. IMO, the fill cap or the Fiero housing is important if the engine requires adding coolant.
You can also run using a modified Fiero thermostat housing w/o the BBV actuator but the supercharger will make slightly more noise and you will lose maybe .5-1 mpg of gas mileage. I have run my 3800SC without the BBV for three years with no harmful effects. There are those here who will disagree but a pinned BBV works on this end.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Charlie1963 AUG 30, 06:40 PM

quote
Originally posted by Dennis LaGrua:

It is possible to cut and re-weld the thermostat housing to fit but keeping the BBV actuator in place requires very careful modifications. You can use the stock 3800 thermostat housing as Joe has said but you will need a high fill point to pour in the coolant . An easy solution is to use a Moroso inline fill housing with a 25lb cap. IMO, the fill cap or the Fiero housing is important if the engine requires adding coolant.
You can also run using a modified Fiero thermostat housing w/o the BBV actuator but the supercharger will make slightly more noise and you will lose maybe .5-1 mpg of gas mileage. I have run my 3800SC without the BBV for three years with no harmful effects. There are those here who will disagree but a pinned BBV works on this end.




It would appear to be fairly easy to move the bbv solenoid to the left away from the tstat housing by modifying the bracket. Doing so however will change the angle between the linkage and the arm. This will cause the valve to open a little bit less.

It looks like the valve would open about 1/8" - 1/4" less by moving the bbv solenoid. Would this small amount make a difference in the performance of the engine?
Charlie1963 SEP 01, 07:56 PM
Here's the modified bracket. I cut off the original mounting holes then made a new part to weld on.



Here it is installed.



Plenty of clearance now between tstat housing.
Dennis LaGrua SEP 02, 03:25 PM

quote
Originally posted by Charlie1963:

Here's the modified bracket. I cut off the original mounting holes then made a new part to weld on.



Here it is installed.


Creative fabrication. Good work!!!!

Plenty of clearance now between tstat housing.



------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Lou6t4gto MAY 19, 01:23 PM
no reason to move it if the thermostat housing is made right. just made 3 of them. look at Ebay. ( 3800 thermostat housing) pictures to show you "orientation"