My 2007 h2
#61
05-21-2019, 02:32 PM
The high flow cats on the OBX long tubes I bought do not do much. Occasionally the check engine light will even come on for a few minutes due to them and dont plan on standing behind it when its running for long. You will choke.... lol
#62
05-21-2019, 02:37 PM
Do you have the 02 bung extenders on the second sensor? I worry more about the visual because I can replace my cats if the factory cats are failing. I here a rattle I think? Hahaha do you have to take the sniffer test for your smog test?
#63
05-21-2019, 07:49 PM
I have been thinking about my H2 and I’m just not satisfied without cam and Headers. I want a stage 3 BTR cam but after several emails, I don’t get a reply and finally I did and it didn’t address my needs or concerns. I think BTR has the best stuff for our Hummers but customer service doesn’t seem to be very good. I’m begging to buy something from you and I don’t get any technical help and I can’t even find a phone number to call! After a little research I think stage 2 will be better because I don’t need to worry about adding a higher stall converter.
Last edited by maxjeep; 05-22-2019 at 08:56 AM.
#64
05-22-2019, 08:49 AM
We have no vehicle inspections here in South Carolina... No I did not use any sort of a bung extension. The sensors are just installed in the pipes like normal.
A stage 3 cam is going to be very choppy and not very well mannered for a daily driver. Also going to that level you will need to replace all the rockers, springs, and pushrods and with the weight of these, once you start going to those levels you will quickly trash the transmission and will need to get a very high performance heavy duty rebuild done or look at converting it to a heavier duty 4L80. The H2 is just not very well suited to be a high performance race truck without doing a lot of work. For performance tips and reading head over to the forums at performancetrucks.net as there will be a lot more info available there.
I'm planning on probably going with a Sloppy Stage 1 cam eventually. With that, it is pushing it a little but you can get away with just the cam only and run it with the stock springs, lifters, and rods.
A stage 3 cam is going to be very choppy and not very well mannered for a daily driver. Also going to that level you will need to replace all the rockers, springs, and pushrods and with the weight of these, once you start going to those levels you will quickly trash the transmission and will need to get a very high performance heavy duty rebuild done or look at converting it to a heavier duty 4L80. The H2 is just not very well suited to be a high performance race truck without doing a lot of work. For performance tips and reading head over to the forums at performancetrucks.net as there will be a lot more info available there.
I'm planning on probably going with a Sloppy Stage 1 cam eventually. With that, it is pushing it a little but you can get away with just the cam only and run it with the stock springs, lifters, and rods.
#65
05-22-2019, 09:03 AM
Mixman I believe you are 100% right and it’s just going to open up a can
of worms and it will still need to be tuned. I just don’t want to take it back apart again and I’m trying to get all I can while it is down.
of worms and it will still need to be tuned. I just don’t want to take it back apart again and I’m trying to get all I can while it is down.
#66
05-23-2019, 01:31 PM
Boxed up nicely
Really nice welds all around
All the brackets look great and seem to be in the right location
I can’t believe how much smaller the core is on the OEM radiator
FedEx just delivered my radiator new and old. I can’t believe the side by side difference. Build quality seems to be very nice and hopefully it will fit like it should. It’s really thick and I like it but I will breath easier once it’s in.
#67
05-23-2019, 09:24 PM
Looks huge installed
Really big radiator! It fits pretty good but the core is twice as thick and the tanks are square compared with the rounded oem. I am not touching anything but it took some massaging. The shroud doesn’t fit because the core is wider and it went inside the oem radiator and it really needs to sit on top of the new radiator and that makes the fan contact the bottom of the shroud. I cut the upper flange to allow it to sit lower but it will need to be spaced 3/8” away from the mounting surface but will be against the radiator. I’m going to do a little research on electric fans because then it wouldn’t matter if it 1/2” higher or lower. The transmission cooler lines fit really good and everything lined up really good.
Last edited by maxjeep; 05-23-2019 at 09:27 PM.
#68
05-24-2019, 10:49 AM
To do electric fans properly and have them reliable is not simple. I actually have everything to change mine over and will be doing it later this summer. I've done it on my GMC truck already.
Proper control of electric fans is done through the PCM. From the factory, electric fans shut off above a certain speed (around 35mph) since the natural airflow makes it pointless to run them. Also factory electric fans in relation to the AC cut on and off based on the AC head pressure. Of course they also cut on/off based on temps as well. All of this can be setup with a custom tune as GM already has all of that in the software as some of the trucks and the 08/09 H2's come with electric fans from the factory. There is also a series/parallel 3 relay setup used to run them at two speeds. You can get the relay module from certain GM trucks from a junkyard and there is actually a place on your underhood fusebox where it mounts specifically for that.
Aftermarket controls generally are not terribly reliable. They also do not disable the fans above a certain speed (except one, which is a setup from Dakota Digital and is not cheap but it is good). Aftermarket ones also just cut fans on high whenever the AC is on (tied into the compressor clutch) regardless of whether the AC really needs them on or not.
I've done a LOT of research on electric fans conversions on full size GM trucks... Best is to get the factory harness with the relay block, the 7/7 blade HD truck factory fans, and get a custom tune done to enable them. In your scenario though I'm not sure if the factory fans will mount to that radiator as they are intended to mount to the factory radiator. There are actually two mounting holes for them in the upper brace just inside the radiator mounting holes which are specifically for the factory electric fans. Done right the electric fans setup will cool it just as well as the original clutch fan. There is also a big bonus of no more school bus roar occasionally when the clutch fan fully engages at lower speeds and you often will have a good bit more power. Not always though - there is no free lunch there.... common misconception is that electric fans free up a lot of power. Removing the clutch fan does indeed do that (also reduces wear on the water pump) however the electric fans need power too, quite a lot of it too. As such when they engage they put a big load on your alternator which increases its internal resistance to provide the power.
Another thing is you will want to be sure your alternator is sized for the additional load. I think the H2's already have a 145A alternator stock which should be okay. Some of the trucks has smaller alternators which cannot deal with the increased electrical load of electric fans.
A couple of people on performance trucks usually are also selling the factory wiring/relay setups. One guy sells just that, the other usually sells with the fans included as well. If you search online for silverado electric fan conversion you will find tons of info on doing it.
https://www.performancetrucks.net/fo...denali-550558/
There are also a few who will make up a relay harness that works the same as the factory harness too which is fine as well. I just prefer the factory one because we already have a place to mount it.
This guy (I've bought a harness from him) does a fantastic job of really making the entire harness look brand spankin' new too. https://www.performancetrucks.net/fo...y-pack-515849/
This weekend I'll take a few pictures as well as get you some measurements of the factory electric fans around the shroud and whatnot so you can measure to see if you might be able to use those.
You can also get a different underhood fuse box housing which has a removable lid on the smaller triangle section which is where the factory electric fans relays and fuse mount. https://www.ebay.com/itm/152863151850 You can see on that one, the smaller section has a separate lid. Its really not required but in the rare case you did blow a fuse, if you have the original cover you have to remove the entire fusebox housing to get to it instead of the smaller second lid.
The below is from the GM Service docs which describes the operation in a little more detail.
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
Important
The right and left cooling fan connectors are interchangeable. When servicing the fans be sure that the connectors are plugged into the correct fan.
The PCM commands the low speed cooling fans ON under the following conditions:
Engine coolant temperature exceeds approximately 94.5°C (202°F).
A/C refrigerant pressure exceeds 1447 kPa (210 psi).
After the vehicle is shut OFF, if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 3 min. regardless of coolant temperature.
The PCM commands the high speed fans ON under the following conditions:
Engine coolant temperature exceeds approximately 104.25°C (220°F).
A/C refrigerant pressure exceeds approximately 1824 kPa (265 psi).
When certain DTCs set.
At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed if required. This insures idle stability by preventing the fans from cycling between high and low speed.
Proper control of electric fans is done through the PCM. From the factory, electric fans shut off above a certain speed (around 35mph) since the natural airflow makes it pointless to run them. Also factory electric fans in relation to the AC cut on and off based on the AC head pressure. Of course they also cut on/off based on temps as well. All of this can be setup with a custom tune as GM already has all of that in the software as some of the trucks and the 08/09 H2's come with electric fans from the factory. There is also a series/parallel 3 relay setup used to run them at two speeds. You can get the relay module from certain GM trucks from a junkyard and there is actually a place on your underhood fusebox where it mounts specifically for that.
Aftermarket controls generally are not terribly reliable. They also do not disable the fans above a certain speed (except one, which is a setup from Dakota Digital and is not cheap but it is good). Aftermarket ones also just cut fans on high whenever the AC is on (tied into the compressor clutch) regardless of whether the AC really needs them on or not.
I've done a LOT of research on electric fans conversions on full size GM trucks... Best is to get the factory harness with the relay block, the 7/7 blade HD truck factory fans, and get a custom tune done to enable them. In your scenario though I'm not sure if the factory fans will mount to that radiator as they are intended to mount to the factory radiator. There are actually two mounting holes for them in the upper brace just inside the radiator mounting holes which are specifically for the factory electric fans. Done right the electric fans setup will cool it just as well as the original clutch fan. There is also a big bonus of no more school bus roar occasionally when the clutch fan fully engages at lower speeds and you often will have a good bit more power. Not always though - there is no free lunch there.... common misconception is that electric fans free up a lot of power. Removing the clutch fan does indeed do that (also reduces wear on the water pump) however the electric fans need power too, quite a lot of it too. As such when they engage they put a big load on your alternator which increases its internal resistance to provide the power.
Another thing is you will want to be sure your alternator is sized for the additional load. I think the H2's already have a 145A alternator stock which should be okay. Some of the trucks has smaller alternators which cannot deal with the increased electrical load of electric fans.
A couple of people on performance trucks usually are also selling the factory wiring/relay setups. One guy sells just that, the other usually sells with the fans included as well. If you search online for silverado electric fan conversion you will find tons of info on doing it.
https://www.performancetrucks.net/fo...denali-550558/
There are also a few who will make up a relay harness that works the same as the factory harness too which is fine as well. I just prefer the factory one because we already have a place to mount it.
This guy (I've bought a harness from him) does a fantastic job of really making the entire harness look brand spankin' new too. https://www.performancetrucks.net/fo...y-pack-515849/
This weekend I'll take a few pictures as well as get you some measurements of the factory electric fans around the shroud and whatnot so you can measure to see if you might be able to use those.
You can also get a different underhood fuse box housing which has a removable lid on the smaller triangle section which is where the factory electric fans relays and fuse mount. https://www.ebay.com/itm/152863151850 You can see on that one, the smaller section has a separate lid. Its really not required but in the rare case you did blow a fuse, if you have the original cover you have to remove the entire fusebox housing to get to it instead of the smaller second lid.
The below is from the GM Service docs which describes the operation in a little more detail.
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
Important
The right and left cooling fan connectors are interchangeable. When servicing the fans be sure that the connectors are plugged into the correct fan.
The PCM commands the low speed cooling fans ON under the following conditions:
Engine coolant temperature exceeds approximately 94.5°C (202°F).
A/C refrigerant pressure exceeds 1447 kPa (210 psi).
After the vehicle is shut OFF, if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 3 min. regardless of coolant temperature.
The PCM commands the high speed fans ON under the following conditions:
Engine coolant temperature exceeds approximately 104.25°C (220°F).
A/C refrigerant pressure exceeds approximately 1824 kPa (265 psi).
When certain DTCs set.
At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed if required. This insures idle stability by preventing the fans from cycling between high and low speed.
Last edited by MixManSC; 05-24-2019 at 11:01 AM.
#69
05-24-2019, 11:11 AM
Thanks! That’s great stuff. I have figured out my shroud after taking a step back. I started thinking just like you said and if I can’t get my shroud to fit I will have the same problem with the electric fans. I also think the oil lines will need to be reworked where they cut across the bottom corner of the radiator. I was looking at a harness from NC ECM? I don’t think I got that right but they will flash your ecm for shipping cost if you buy the harness and it’s around 150$. I think it’s going to be a winter project. It’s starting to get hot here and I have to get my gears done as soon as possible and that will be it for awhile. It’s summer and I’m a single Dad so I’m trying to finish so my Son and I can have a nice little road trip.
#70
05-24-2019, 11:47 AM
PCM of NC... heard of them but do not really know anything about them.
Doable using a third party harness. I just worry about reliability with aftermarket stuff (in regards to connector ratings, crimp quality, relay ratings, etc) for something that critical. Breaking down is no fun....
Doable using a third party harness. I just worry about reliability with aftermarket stuff (in regards to connector ratings, crimp quality, relay ratings, etc) for something that critical. Breaking down is no fun....