Its time for a V8

[Zero]

SO, as you can tell by my thread title, I think it is getting to be about that time that I start looking into an engine swap.

What i would like to do is drop in the 5.3l LH6. For a few reasons....1. The v8 engine in the EXT truck is supposed to get around 2mpg more then the inline 6 I currently have just because you dont have to drive the engine as hard to more the extra weight. This is even more true now that I have the big tires put on, and carry more weight on a regular basis. I started with a truck that was underpowered, and after some mods, and some camping gear, and passengers......the 6cyl just isnt cutting it for me.

Another thing to consider, I have a 2005 4.2l which was made before the revised 2006 6cyl was released which among other changes received a bump in power.

I would prefer to find an LH6 engine out of a trailblazer EXT because I assume it will make mounting, and plugging in sensors less of a problem.

If anyone can send me any links to someone who has done this swap, comments, or know right away of a few new parts I will need....PLEASE SPEAK UP!

I need to build up as much info as possible so I can buy the right parts the 1st time.

thanx

Z

[Philberto]

I'll be looking on with bated breath... Been thinking of a swap myself, though I'd be looking at a L99 (AFM motor from Camaro) or L76 (6.0L motor from newer Avalanches), probably L76 (VortecMax). I know you may have issues with communication between the ECM and BCM, and may want to talk to Pcm4less to find out what can be done about that. Otherwise, I'm sure you can tweak your tranny to handle the power... those trannies have ben built to handle much more in Camaros... Best of luck.

[bartonmd]

Been covered pretty extensively on Trailvoy... Nobody's done it because it's a bad idea, given that you can buy a SWB V8 for less than the difference in money that a swap costs, and have no time in it...

I have a SWB V8, and have done some looking at the I6 and V8 TBs...

- The engine mounts differently, so you'll need the V8 engine mounts.
- Because the engine is shorter, but still has to have the mechanical fan in the same place, the transmission and T-case are moved forward with the engine. This is only a big deal because the welded in transmission mount crossmember needs to be about 3" farther forward for the V8.
- The front drive shaft is shorter on the V8 (can come from donor EXT)
- The rear drive shaft is longer on the V8 (would have to have yours lengthened by ~3" or get one from a SWB V8)
- Computers won't talk... I6 uses a PCM, while the V8 uses an ECM and a seperate controller for the transmission.
- Spring rates change
- Radiator changes
- Rear axle out of EXT or SWB V8

You'd be time and money ahead to take the aftermarket stuff off of yours, sell it, and buy an '06-'08 SWB V8 to start with...

If you don't already have at LEAST 4.11 gears, preferrably 4.56 gears, and a PCM tune with all the T/M taken out, you're not to the point of making the V8 decision yet... The I6 has plenty of power. Spin it. That's what it's built for... If it wasn't made to spin, it wouldn't have 4 valves/cylinder, DOHC, and VVT...

FYI, the V8 gets about the same, or slightly less than the average I6 does... As shown in the "corrected" EPA numbers, as well... Your engine theory is wrong... The harder a gasoline engine works (while staying in closed loop control), the more effecient it is... The more open the throttle is, the less vacuum the engine is pulling, the better the volumeteric effeciency is... There was a VE/gas mileage/tire thread on either here or the other site, where James and I both explain the whole thing, so I'm not doing it again...

Mike

[The Roadie]

Personally, I agree with Mike. Until you have 4.11 gears, you ARE strangling the performance of any engine you put in, and any tune you put on top of it. Save the engine swap money for camping gear and gadgets.

[bgwolfpack]

Zero, put the stock tires back on and get the mileage you want along with more power. It may look stupid but it will get the results and wouldn't cost a dime.

[Zero]

Thanx for all of your inputs. I will have to take a look around and see what I can get into. otherwise I will look into a gear change.

[Zero]

Would you guys say it would be better worth my time and money to replace the 2005 6cyl I have with an 06 or 07? I believe they received updated heads, a bump in power, and a few other goodies. Am i correct?

[Philberto]

I'd say you'd be better off just changing the head (IIRC that's the major difference between the two engines). Have you tried a PCM4Less tune yet? I'm going to be sending mine in for a tune I bought back last Labor Day, so I'll let you know the results.

[bgwolfpack]

I'd say you'd be better off just changing the head (IIRC that's the major difference between the two engines). Have you tried a PCM4Less tune yet? I'm going to be sending mine in for a tune I bought back last Labor Day, so I'll let you know the results.

Z, Phil may be on to something here.

[Zero]

I'd say you'd be better off just changing the head (IIRC that's the major difference between the two engines). Have you tried a PCM4Less tune yet? I'm going to be sending mine in for a tune I bought back last Labor Day, so I'll let you know the results.

Yes I have a PCMForless tune. It made a huge difference. And def getting better gas millage now too. Although one problem that seems to have us stumped is they cant get the speedo to read the right speed, and , my cruise control doesnt work.

Im gona see what i can fix using something like HP tuners, maybe need a tech tool......

but other then those problems the tune is great.

I guess if I am gona stick with this 6cyl for a while I may try to look into a new head, and some headers. Especially with people cracking theirs when they go in the water.

[bgwolfpack]

Great subjects, both this and the SS brakes, but shouldn't they be in the Discussion thread instead of Fab work? My understanding was this is for completed work.

[Trail X]

Yes I have a PCMForless tune. It made a huge difference. And def getting better gas millage now too. Although one problem that seems to have us stumped is they cant get the speedo to read the right speed, and , my cruise control doesnt work.

The CC is controlled by the PCM only. Their tuning shouldn't have touched the programming one bit. However, it is my understanding that GM built in a feature that the PCM will turn the CC off if it notices something wrong with the system. This can be a fault in a sensor or similar issue that doesn't warrant a CEL. The PCM should store the code in the memory, but it cannot be read by the Scangauge. You'll need a Tech II or other advanced reader.

My speedo was never fixed either... one of the many reasons I got rid of my PCM tune. I've taken some wise advice to heart... trust the OEM engine engineers.

Especially with people cracking theirs when they go in the water.

What is this in reference to? Who's cracked what? Did I miss something?

[Zero]

I was refering to people who crack their cast manifolds when doing high water crossings.

I guess it will be off to the dealer then if I need a tech tool. I want to check though. If they go in to fix just the CC, will that in anyway lead to me losing my tune?

[Philberto]

Speedo I can live without... better gas mileage = more money = more trips offroading. I don't really use my CC either, but since I work at a dealer, I could always play around with the Tech2 and see what's up.

[Zero]

Been covered pretty extensively on Trailvoy... Nobody's done it because it's a bad idea, given that you can buy a SWB V8 for less than the difference in money that a swap costs, and have no time in it...

I have a SWB V8, and have done some looking at the I6 and V8 TBs...

- The engine mounts differently, so you'll need the V8 engine mounts.
- Because the engine is shorter, but still has to have the mechanical fan in the same place, the transmission and T-case are moved forward with the engine. This is only a big deal because the welded in transmission mount crossmember needs to be about 3" farther forward for the V8.
- The front drive shaft is shorter on the V8 (can come from donor EXT)
- The rear drive shaft is longer on the V8 (would have to have yours lengthened by ~3" or get one from a SWB V8)
- Computers won't talk... I6 uses a PCM, while the V8 uses an ECM and a seperate controller for the transmission.
- Spring rates change
- Radiator changes
- Rear axle out of EXT or SWB V8

You'd be time and money ahead to take the aftermarket stuff off of yours, sell it, and buy an '06-'08 SWB V8 to start with...

If you don't already have at LEAST 4.11 gears, preferrably 4.56 gears, and a PCM tune with all the T/M taken out, you're not to the point of making the V8 decision yet... The I6 has plenty of power. Spin it. That's what it's built for... If it wasn't made to spin, it wouldn't have 4 valves/cylinder, DOHC, and VVT...

FYI, the V8 gets about the same, or slightly less than the average I6 does... As shown in the "corrected" EPA numbers, as well... Your engine theory is wrong... The harder a gasoline engine works (while staying in closed loop control), the more effecient it is... The more open the throttle is, the less vacuum the engine is pulling, the better the volumeteric effeciency is... There was a VE/gas mileage/tire thread on either here or the other site, where James and I both explain the whole thing, so I'm not doing it again...

Mike

Over looking this, it would be easier for me to do the sawap then a short wheel base model, because I have an ext. This is something I may still keep on the back burner

[HARDTRAILZ]

fwiw...my cc never quit working and they got my speedo right on. I have no complaints about the pcmforless experience. Better shifts, mpg and drivability.

[The Roadie]

Who's cracked what? Did I miss something?

I cracked my exhaust manifold once on a Coyote Canyon water crossing what was only about 14-16" deep. Not certain how. Since replacing it, I've been through the SAME water up to about 20" with no issues. Still scary, as Zero can confirm.

[HARDTRAILZ]

I would venture to say that it was not the water crossing that did it then. It would seem coincidence that it broke during a water crossing if no one else has had that issue and you can not replicate it.

[bartonmd]

Been covered pretty extensively on Trailvoy... Nobody's done it because it's a bad idea, given that you can buy a SWB V8 for less than the difference in money that a swap costs, and have no time in it...

I have a SWB V8, and have done some looking at the I6 and V8 TBs...

- The engine mounts differently, so you'll need the V8 engine mounts.
- Because the engine is shorter, but still has to have the mechanical fan in the same place, the transmission and T-case are moved forward with the engine. This is only a big deal because the welded in transmission mount crossmember needs to be about 3" farther forward for the V8.
- The front drive shaft is shorter on the V8 (can come from donor EXT)
- The rear drive shaft is longer on the V8 (would have to have yours lengthened by ~3" or get one from a SWB V8)
- Computers won't talk... I6 uses a PCM, while the V8 uses an ECM and a seperate controller for the transmission.
- Spring rates change
- Radiator changes
- Rear axle out of EXT or SWB V8

You'd be time and money ahead to take the aftermarket stuff off of yours, sell it, and buy an '06-'08 SWB V8 to start with...

If you don't already have at LEAST 4.11 gears, preferrably 4.56 gears, and a PCM tune with all the T/M taken out, you're not to the point of making the V8 decision yet... The I6 has plenty of power. Spin it. That's what it's built for... If it wasn't made to spin, it wouldn't have 4 valves/cylinder, DOHC, and VVT...

FYI, the V8 gets about the same, or slightly less than the average I6 does... As shown in the "corrected" EPA numbers, as well... Your engine theory is wrong... The harder a gasoline engine works (while staying in closed loop control), the more effecient it is... The more open the throttle is, the less vacuum the engine is pulling, the better the volumeteric effeciency is... There was a VE/gas mileage/tire thread on either here or the other site, where James and I both explain the whole thing, so I'm not doing it again...

Mike

Over looking this, it would be easier for me to do the sawap then a short wheel base model, because I have an ext. This is something I may still keep on the back burner

OK, then you won't have to get a rear axle or big brakes from an EXT... Everything else is still correct...

If you're trying to make a V8 EXT, you'd be MUCH better off just buying the same year EXT as you have, only with a V8... I was thinking you had an older I6 and would be extra money to trade up to a n '06-'08 V8 SWB... Same year V8 difference wouldn't pay for the engine mounts, wiring, and welding you'd have to do, and that's if you get the drivetrain for free!

Mike

[Trail X]

I would venture to say that it was not the water crossing that did it then. It would seem coincidence that it broke during a water crossing if no one else has had that issue and you can not replicate it.

I've been almost tire-deep in water (and I think you have too)... no problems other than the wheel bearing ... and maybe my disconnect

However, Bill may have been working his engine harder leading up to the crossing. If you get something hot enough and get it in contact with enough water in the wrong spot, it could probably fracture, especially if it's thin enough.