[Tachyon]

So I just bit the bullet and had a GMPP HT383E swap done on my 3/4 4x4 99 Suburban.
because of the high km on the vehicle, I also put in a new 4L80E as well.
The dealer did an awesome job and so far I'm quite happy with the results.
I made a few other changes/ additions as well based on my research about this swap. I added a set of JBA shorty headers which I wrapped with DEI titanium braided header wrap. Then after the first part of the break in was complete, I programmed the PCM using a Hypertech 32000 Max Energy programmer.

For anyone contemplating this swap, it does work without any issues and I'll go into detail on the swap, tech, gotchyas, etc. later as I get time.

For now, the short version is that this works well, has minimal issues, and so far I am quite pleased with the results.

Will update and add details as I get time.

thanks,
Tachyon

 

[silveradotrailblazer]

Glad its all working out so good. Keep use updated.

 

[Tachyon]

Well, after a couple months use I have to say I'm very happy with this swap.

The HT383E engine package is very impressive. It really is a drop in replacement for the stock 350 and works with all the existing accessories and computer. The engine has great power and runs very smooth, especially for an externally balanced engine. Now that it's mostly broken in, fuel economy is getting to be quite good as well (if I can keep my foot out of it).
I have no doubt that with proper care and maintenance, I could keep, and use this truck for another 10 years. I hope so, because that's the plan.

For anyone looking to install an HT383E in their GMT400 Suburban, or similar year Tahoe, Silverado, or Sierra, I have no reservations about recommending it. This is not a hot rod engine, or a monster truck off road power plant, but for someone wanting to build a sturdy daily driver workhorse that can tow all day long, this is a great option.

Consider that you could find a great used 7-9 seat 92-99 Suburban 2500 for under $5000. Now add $7500 for a new HT383E and new 4L80E transmission. Then a couple thousand for basic maintenance (ball joints, u joints, brakes, etc.) and you have a like new vehicle that for under $15000 can replace most $50000+ new SUVs. Personally I think this is a helluva deal.

Now, here's some thoughts, tips, Ideas from what I've learned so far.

- If you do this, you really should replace or rebuild the tranny as well. Possibly also the transfer case. The power of the new engine is much closer to the limits of the 4L80E than the stock 350 and that makes it tough enough on a new transmission. Your 15 year old tranny probably doesn't stand a chance.
- Buy a PCM programmer, and make it one that can firm up transmission shifts (ie increase line pressures). Even if you don't feel you need the performance increase of the chip, you probably want the extended transmission life you'll get from the firmer shifts. The firmer shifts mean less slippage and less heat and wear on your transmission as well as the ability to better handle the increased power of the new engine.
- Install headers. This is SO much easier to do at the time of the engine swap, they are cheap and it's worth it in every way. I chose a pair of JBA shorty headers that are emissions compliant and drop right in in place of the factory manifolds so you can use the factory exhaust system if you want. More importantly, you can pass a smog test. Most of all, the new engine needs to breathe to be efficient. Both power and fuel economy will benefit. It's win win.
- Install a programmer or get a custom tune. I'm running a Hypertech Max Energy P/N 32000 programmer currently and it seems to work pretty well with this package even though Hypertech doesn't officially support it. Even though the Max Energy is designed for the factory 350, it seems to work well on the HT383E, definitely better than the factory programming.
It also allows you to increase shift firmness as mentioned before, and you can also adjust shift points, redline, speed limiter, and adjust for tire diameter changes.
The only down side is that the Hypertech (and every other tuner I looked at) requires 92 octane fuel.
Ultimately, I'd love to have some EFI Live hot shot create a custom tune for me, but for now the Hypertech is working pretty well.
- Consider also installing a cold air intake kit like from K&N and a new exhaust system. I have the feeling this engine would really come alive with better airflow.
- replace your fuel filter.
- Check your fuel line pressure and replace your fuel pump if necessary.
- Check your EGR valve and replace if necessary.
- Be careful how you route the plug wires. They are custom cut for the engine and don't have a lot of slack. Don't route them around dipstick tubes or other obstacles in such a way as to put them under tension. I've already had one plug wire come unplugged on a really bad washboard road due to pressure from the dipstick tube. I had to adjust the slack on that wire around the tube to remove the tension. A V-7 is nowhere near as smooth running and powerful as a V-8. ;')

Finally, and most important. Get a copy of the engine installation and break-in instructions from GM and FOLLOW THEM TO THE LETTER!! The break-in process is detailed in the manual and you should not just install the engine and drive off.

 

[phoebeisis]

Wow,I'm jealous.
My 1998 Suburban 1/2 ton 2wd has 216,400 on it-5.7- so I figure one day I'll have to replace the motor(even though it is running great and gets 21 mpg on long hy trips at 62mph- it is a sweet motor-lucked out paid $2950 for it 4 years ago and 21,000 miles ago)

I have been eyeballing that 383E-
My question
Can I drop in a 4L80E-just drop it in-plug in electronics-and drive off? My 4L60E certainly isn't rated for 430 lb ft so it would eat it-maybe eat the rear end also??

Must say I love my Suburban-best vehicle for the $$ I have ever owned.It can comfortably evacuate our 1-2 dogs, 4 cats,and 3 adults with plenty of stuff just in case of another hurricane.It makes a great second car-we try not to put lots of miles on it because of the 13-14 mpg city, but considering its versatility and HUGE cargo capacity 13-14 mpg city isn't bad.

Yeah I'm jealous
You are right-older Suburbans are dirt cheap, parts are cheap , they are relatively easy to work on-hard to beat for what they can do for not a lot of $$.Put $10,000-$12,000 in one and you have a $50,000 vehicle for 1/3 the price.Or cheapout like me and put $1200+$2950=$4200 and still have a competent vehicle-not as much fun of course-or as reliable.
Charlie

 

[silveradotrailblazer]

Sounds like you have a sweet running 'Burb with those mods. Any engine bay pictures?

 

[stephan]

X2 on the 383 ci for towing Tachyon. I'll bet you're enjoying the extra torque. Good write up!:great:

 

[Tachyon]

Wow,I'm jealous.
My 1998 Suburban 1/2 ton 2wd has 216,400 on it-5.7- so I figure one day I'll have to replace the motor(even though it is running great and gets 21 mpg on long hy trips at 62mph- it is a sweet motor-lucked out paid $2950 for it 4 years ago and 21,000 miles ago)

I have been eyeballing that 383E-
My question
Can I drop in a 4L80E-just drop it in-plug in electronics-and drive off? My 4L60E certainly isn't rated for 430 lb ft so it would eat it-maybe eat the rear end also??

Must say I love my Suburban-best vehicle for the $$ I have ever owned.It can comfortably evacuate our 1-2 dogs, 4 cats,and 3 adults with plenty of stuff just in case of another hurricane.It makes a great second car-we try not to put lots of miles on it because of the 13-14 mpg city, but considering its versatility and HUGE cargo capacity 13-14 mpg city isn't bad.

Yeah I'm jealous
You are right-older Suburbans are dirt cheap, parts are cheap , they are relatively easy to work on-hard to beat for what they can do for not a lot of $$.Put $10,000-$12,000 in one and you have a $50,000 vehicle for 1/3 the price.Or cheapout like me and put $1200+$2950=$4200 and still have a competent vehicle-not as much fun of course-or as reliable.
Charlie

Well, the HT383E is actually designed for the half ton models, so I assume they take into consideration the fact that those have a 4L60E in them. That said, I'd look into alternatives.
You could swap in a 4L80E, though I'm not sure what would be involved in that. Probably wouldn't work with the factory computer so you'd need the GMPP standalone controller module. Then you'd be stuck always looking at a lit up MIL unless you could find a programmer to disable it. Another option might be to get a built third party 4L60E that can handle the torque.
I don't really know what to say because the HT383E is clearly rated for more torque than the 4L60E is supposed to be rated for so something is up. I'd look at the GMPP 4L70E Supermatic Transmission. MIght be a good alternative option.

As for the engine, yeah, it's pretty much drop in and go.. Works with the factory everything. Computer, wiring, etc. That said, I'd still highly recommend headers and a programmer.

---------- Post added at 03:11 AM ---------- Previous post was at 03:07 AM ----------

Sounds like you have a sweet running 'Burb with those mods. Any engine bay pictures?

I could certainly take some, but it's pretty boring under the hood as it looks exactly like the original factory engine, just cleaner and newer. If I hadn't added headers, you wouldn't even be able to tell anything was different.

 

[2COR517]

Would you describe the GM spec break in procedures as "drive it like you stole it" or more like "drive like grandma"

A custom tune from Black Bear or some of the others would get you back to 87 octane.

 

[Tachyon]

HT383E Break In procedure

Would you describe the GM spec break in procedures as "drive it like you stole it" or more like "drive like grandma"

Decide for yourself...

Start-up and Break-in Procedures
1. After installing the engine, ensure the crankcase has been filled with 10w30 motor oil (non-synthetic) to the recommended
oil fill level on the dipstick. Also check and fill as required any other necessary fluids such as coolant, power
steering fluid, etc.
2. The engine should be primed with oil prior to starting. Follow the instructions enclosed with the tool. To prime the
engine, first remove the distributor to allow access to the oil pump drive shaft. Note the position of the distributor
before removal. Install the oil priming tool, GM part number 12368084. Using a 1/2" dill motor, rotate the engine oil
priming tool clockwise for three minutes. While you are priming the engine, have someone else rotate the crankshaft
clockwise to supply oil throughout the engine and to all the bearing surfaces before the engine is initially started. This
is the sure way to get oil to the bearings before you start the engine for the first time. Also, prime the engine if it sits
for extended periods of time. Reinstall the distributor in the same orientation as it was removed.
After the engine has been installed in the vehicle, recheck the oil level and add oil as required. It is also good practice
to always recheck the CMP offset after removal and reinstallation of the distributor. See step 4 or engine specifications
for the proper distributor information.
3. Safety first. If the vehicle is on the ground, be sure the emergency brake is set, the wheels are chocked and the car
cannot fall into gear. Verify everything is installed properly and nothing was missed.
4. Ignition timing is non adjustable on this engine. The high voltage switch (distributor) must be installed correctly for
proper camshaft position (CMP) retard offset or the service engine soon light will be illuminated and DTC P1345 will
be set in the powertrain control module. (see GM service information for details)
5. When possible, you should always allow the engine to warm up prior to driving. It is a good practice to allow the oil
sump and water temperature to reach 180°F before towing heavy loads or performing hard acceleration runs.
6. Once the engine is warm, verify correct camshaft position (CMP) retard offset using a scan tool.
7. The engine should be driven at varying loads and conditions for the first 30 miles or one hour without wide open throttle
(WOT) or sustained high RPM accelerations.
8. Run five or six medium throttle (50%) accelerations to about 4000 RPM and back to idle (0% throttle) in gear.
9. Run two or three hard throttle (WOT 100%) accelerations to about 4000 RPM and back to idle (0% throttle) in gear.
10. Change the oil and filter. Replace with 10w30 motor oil (non synthetic) and a PF25 AC Delco oil filter. Inspect the oil
and the oil filter for any foreign particles to ensure that the engine is functioning properly.
11. Drive the next 500 miles under normal conditions or 12 to 15 engine hours. Do not run the engine at its maximum
rated engine speed. Also, do not expose the engine to extended periods of high load.
12. Change the oil and filter. Again, inspect the oil and oil filter for any foreign particles to ensure that the engine is functioning
properly.
13. Do not use synthetic oil for break-in. It would be suitable to use synthetic motor oil after the second recommended oil
change and mileage accumulation. In colder regions, a lower viscosity oil may be required for better flow characteristics.

Regarding the oil recommendation, I intend to switch to Amsoil 5W30 at my upcoming third oil change.

A custom tune from Black Bear or some of the others would get you back to 87 octane.

I might just take a look at that in the future.

 

[Tachyon]

Update - Added intake and exhaust systems.

The work on our old faithful '99 continues. The HT383E is a year old now and runs well but hasn't been able to breathe through the factory intake and exhaust systems so I've been addressing that as funds and time allow.

First, a few months ago, I installed a K&N cold air kit. This was a fairly straight forward install, though getting the stock system out was a pain.
The K&N system made a huge difference in the vehicle and noticeably improved power and performance. Plus, it sounds cool when you floor it. ;')

Just this week, I addressed the final piece of the puzzle, the exhaust system. I ordered a Magnaflow cat replacement and Y-Pipe as well as a Magnaflow cat back system. I found an awesome shop in our new hometown of Edmonton, Promax Performance ( http://www.promaxperformance.com/ ), and they not only got me a great price on the parts, but they did excellent work on the install.

The obvious question is, how does it all perform now? Well, I can't honestly say yet. I've only been able to drive around town in mostly stop and go traffic. Plus the computer is now in re-learn and I believe the cats will have a sort of break in period before they are at full efficiency. That said, seat of the pants feel is good and the sound of the Magnaflow system is awesome. It's just what I wanted. Not too loud or annoying during everyday driving, just a cool burbling tone. And when you get in it, it makes a sweet, deep toned muscle car sound. Nice.

I've added some pictures which I'll try to describe.

First a couple of pics of the old factory system which had seen better days.
The rest show the Magnaflow system and how nicely it fits in place of the factory system. It actually looks factory, except better. You can also see where the passenger side of the Y-pipe mates up to the JBA shorty headers which are wrapped.
You can also see a few pics that show how Promax Performance did an awesome job rerouting the O2 sensor harnesses to the new cat locations. They even added some heat shield to protect the cables. This was necessary because the Magnaflow cats both fit in the space where the factory front cat was located.

 

[rileyjr16]

The work on our old faithful '99 continues. The HT383E is a year old now and runs well but hasn't been able to breathe through the factory intake and exhaust systems so I've been addressing that as funds and time allow.

First, a few months ago, I installed a K&N cold air kit. This was a fairly straight forward install, though getting the stock system out was a pain.
The K&N system made a huge difference in the vehicle and noticeably improved power and performance. Plus, it sounds cool when you floor it. ;')

Just this week, I addressed the final piece of the puzzle, the exhaust system. I ordered a Magnaflow cat replacement and Y-Pipe as well as a Magnaflow cat back system. I found an awesome shop in our new hometown of Edmonton, Promax Performance ( http://www.promaxperformance.com/ ), and they not only got me a great price on the parts, but they did excellent work on the install.

The obvious question is, how does it all perform now? Well, I can't honestly say yet. I've only been able to drive around town in mostly stop and go traffic. Plus the computer is now in re-learn and I believe the cats will have a sort of break in period before they are at full efficiency. That said, seat of the pants feel is good and the sound of the Magnaflow system is awesome. It's just what I wanted. Not too loud or annoying during everyday driving, just a cool burbling tone. And when you get in it, it makes a sweet, deep toned muscle car sound. Nice.

I've added some pictures which I'll try to describe.

First a couple of pics of the old factory system which had seen better days.
The rest show the Magnaflow system and how nicely it fits in place of the factory system. It actually looks factory, except better. You can also see where the passenger side of the Y-pipe mates up to the JBA shorty headers which are wrapped.
You can also see a few pics that show how Promax Performance did an awesome job rerouting the O2 sensor harnesses to the new cat locations. They even added some heat shield to protect the cables. This was necessary because the Magnaflow cats both fit in the space where the factory front cat was located.

Thats a very nice mod. I wanted to replace my old 4.3 with a big old 383 when I had my 97 but never had the money nor the time.

Just gotta ask though, who beat up the transmission pan? :lol:

 

[Tachyon]

Thats a very nice mod. I wanted to replace my old 4.3 with a big old 383 when I had my 97 but never had the money nor the time.

Just gotta ask though, who beat up the transmission pan? :lol:

Heh, yeah it does look like it doesn't it. No it's fine. I had a new 4L80E put in when I did the engine swap. The replacement tranny's come with that pan. My guess is that some other model requires that indentation in the pan so they just put that pan on all the replacement tranny's to reduce the part numbers they have to stock.
But every time I look under there, I think the same thing for half a second "Aww crap, what'd I hit...oh wait..."

The dent in the factory muffler and crossover pipe on the other hand, I'd like to know the story on those. They were there when we bought the vehicle so they're a mystery.

 

[Tachyon]

UPDATE

One thing I didn't mention in the previous post is that when the exhaust system was installed, we discovered a problem with the header on the passenger's side. We think the bolts weren't torqued properly at install because two were missing! We had developed a bad exhaust leak around the header flange and it made a terrible racket and affected performance.
I went back this last Saturday and the awesome team at Promax Performance took the header off, cleaned off the head, straightened and belt sanded the flange flat and re-installed with a new Mr. Gasket gasket and some copper seal. They also checked the driver's side and found several loose bolts there. Fortunately no gasket damage or leak was found on the driver's side. After they buttoned the whole thing back together and it's now leak free.

I took it on it's first real road trip today on the highway and included an couple of full power on ramp merges.

WOW!! What a difference. It's like a whole new vehicle. The engine is now silky smooth and the exhaust has a smooth, mellow bass tone that's not too loud. When you go full throttle it's a smooth bass howl. The best way I can describe the exhaust tone is that it's like Barry White calmly saying "OK baby, hang on, we're gonna go fast now, oh yeah".
I am now super impressed with the Magnaflow system. It's a perfect match for the rest of the power-train. In fact the power-train package as a whole is complete now. It feels perfect. Smooth, powerful, integrated. It's like it came from the factory this way, but from a secret cooler factory where they all love cars and hot rod and cool jazz.

Suddenly it feels like I have a brand new, off the assembly line truck with a hidden label somewhere that reads something like GT, or Limited Edition.

At this point I can't possibly overstate how happy I am with this powertrain combination. The K&N Intake, the HT383E engine, the Magnaflow exhaust and the Hypertech program are now like a bad ass jazz quartet that's been playing together for years.

Oh, and one more piece of awesome. I was heading down an on-ramp this morning, it was a two lane ramp that merged into one lane just before merging onto the highway. We were going from a stop light to the 110Km/h speed limit and there was a Navigator in the merge lane that thought he would just jump out of the light in front of me and beat me to the merge point. Man was he surprised. He was 3 truck lengths back by the time we got there. Ha, suck it Ford!

 

[phoebeisis]

THANKS for the extensive update!!
So in short- you love it- it is a winner-no real downside.
Any chance you have any HY MPG numbers?
Yeah I'm a mpg nut-
Little odd owning a Suburban- but mpg improvements on 1/2 tons save a lot more gas and $$ than mpg improvements on most cars.
Do you think it get maybe 15 mpg at 60 mph-that would be pretty good-roughly stock-mpg considering all the utility of a large 4x4 tow capable 3/4 ton vehicle
"Someday" Ill upgrade my 1/2 ton 2wd 98 Suburban-new motor-or maybe by a used 2004 when gas spikes and folks stupidly bail out of their Suburbans-like they did in 2008 and in 1979.1980.
Yeah-thanks for the update.It is REALLY HARD to beat an OEM genuine GM engine for reliability. You can get more power for less-from the aftermarket-but it just won't be as reliable-simple as that. Reliability is worth another $1500 spread over the 10-years of its extended life.
And the aftermarket crate motor builders-LIE about their HP torque-their claims are never checked-and usually require extensive intake and exhaust changes.
And they break-more power-means more breakage
Yeah-smart move
For $15,000 you get new upgraded drivetrain-with more or less the same Suburban utility and road trip comfort(we use ours for road trips-and evacuate 2 dogs 5 cats 3 adults-4 miles W of NOLA). The only thing you are shorted on is the somewhat better mpg of the 2007 ons-maybe 3 mpg hy-2 mpg city
but for $35,000-you can buy LOTS of gas.

If you get a chance let us know hy mpg- or just regular fill up mpg-which I would guess would be about 10-11 mpg in mixed city suburban hy driving.

Thanks
Charlie

 

[Tachyon]

The Fuel Economy Question

THANKS for the extensive update!!
So in short- you love it- it is a winner-no real downside.
.
.
.
If you get a chance let us know hy mpg- or just regular fill up mpg-which I would guess would be about 10-11 mpg in mixed city suburban hy driving.

Thanks
Charlie

Regarding your first part. Yes, I am extremely happy with the final outcome of this long powertrain journey. I also really can't point out any downside other than not having the money to do it all at once and having to spread it out over a year and a half. But like I said before, given what I've now spent on the vehicle and the results I've obtained versus buying a new vehicle and still having payments on it, it's a no brainer with a win/win outcome IMO.
I think that taking the time to do a lot of research and finding the right people to help is what has made this go so smoothly and why I'm so happy with the outcome.

Regarding Fuel Economy.
I've wondered about this too. I do keep a fuel log so I have fuel economy information. I've assumed that at this point I should see some MPG improvements in normal driving and especially highway driving IF I can keep my foot out of it. At this point it's not only responsive, but it's smooth so you forget and drive it like a car, a fairly sporty one, and you don't notice you're doing it. It will be hard to do a full tank without any peppy driving.

I fully intend to track fuel economy both with driving my normal routine, and on a highway trip. I'm also very curious to see the numbers.
That said, I'm not going to count this first tank for two reasons.
I) The computer is in relearn so it will be a few hundred km before I feel it's settled in.
II) The new cats are not "broken in" yet. I think this will also take a few days.

That said, I filled it up the night before the header repair and drove it to the shop the next day. I think it had 14km on the trip by the time they got it. I took one short 45km highway run and a run through the city to test it it out get everything up to temp etc. I now have 145km on the trip and have used an eighth of a tank so far! This is really good compared to previous fuel use. This puts me on track for 17MPG (US gallons) and 21MPG (Imperial Gallons). Not that I expect it to end up that high, but it's impressive anyway even for a rough estimate.

I'll certainly update once I get some real numbers.

 

[rileyjr16]

we use ours for road trips-and evacuate 2 dogs 5 cats 3 adults-4 miles W of NOLA).

Did yall evac for this one?

 

[Skippy]

I love the fact you've updated this post periodically. It's a great testament to the upgrades you've made.

Well done.

-Skippy

 

[Tachyon]

I love the fact you've updated this post periodically. It's a great testament to the upgrades you've made.

Well done.

-Skippy

Well I hate when I'm looking for someone's experiences on something and I find posts related to the topic online somewhere and they post something like "So I'm going to try it tomorrow...." and that's the last post and it's a year old.

I know I am very careful about how I part with my hard earned money so if I can help anyone else learn from my experiences and my mistakes then I'm happy to share the info. Actually I was worried someone would be thinking "I wish he'd shut up already and stop updating this old post". ;')

 

[Skippy]

HAHAHA! Me too! It's why I posted here, and stay active with my account... to periodically update my towing experience with my rig.

I despise the "I'll update when I get them put on!" and that was listed in 2008. Yeah. Promises promises.

It's why I took the time to thank you for your updates. Too often people come in and read and appreciate without saying anything.

Cheers!

-Skippy

 

[Tachyon]

Future

Powertrain wise, I'm very happy with this upgrade and consider it pretty much complete. I have lots more plans for the rest of the truck, but I prioritized on the powertrain and got it done first.

However, there is one thing I've been thinking about doing and that's to replace the Hypertech program with a custom tune. That said, I don't really have the time and experience to mess with EFI Live at this point (or the funds for that matter). Maybe down the road. If I come into some cash maybe I'll look up someone that does them locally and just pay for a pro to do it. Don't get me wrong, the Hypertech is great. But it's designed for a stock 350 and stock powertrain. At this point I feel like there are efficiencies being left on the table and I think there's power and economy that can still be wrung from the system.

Also I'd like to dyno the system A) to satisfy my curiosity about the power output B) to find the power and torque curves so I can optimize WOT shift points.