Engine builds...Why so hard?

[Amelio]

I have been curious to know about the difficulties of the engine rebuilds in our cars. I have been hearing for years that just an ordinay engine shopp can not build them correctly. I am lost...........

I have built 5 of these engines along with some SBC and pontiac and some imports. I want to know what I am missing or maybe what I have over looked?

The first time my first GN needed a build I payed some one because all I heard was they are special and not just anyone could do it. when that engine broke I rebuilt it myself with no issues.

Some one please clue me in.............

 

[Camfreek]

I am not sure but......

I think the reasoning lies with the fact that most engine shops really only build up natuarlly aspiarated motors, and the other thing I really noticed is the fact that all Chevy and Ford parts are really a dime a dozen. Turbo motors are completely different motors compared to others. Feel free to correct me if I am wrong on this. I have been building motors myself for many years, but I really only deal with carbed motors and some with superchargers. I can tell from doing all of this turbos are a different ball game and can go down hill much faster then others. The biggest problem I have noticed and always will being so picky like I am:wink: Most engine shops think they know everything out there that there is to know, and that is far from the truth I had an old Ford 351C and took it in and asked the guy to punch it out 10 over seeing that I had the pistons and I know how weak the castings are on these motors. Well come time to pick it up and mic everything out, the dumbass punched it 30 over and boy was I pissed and I still am Not to easy to find a 351C block anymore. Long story short we had a few words and he ordered a set of pistons for me and we called it even and he said the motor would last five seasons at the track, well I guess he knew everything cuase on the 3rd pass it cracked the block right in the cylinder wall like I know it would Bye bye hard earned money and what could have been a good motor if he would have listened. That is why I will only take my car somewhere where thay can prove how good they are and there are not to many around here

 

[RmvBfrFlght]

The only answers I can provide is from what I've read here. Myself, I've built my fair share of SBC's and Pontiac motors. However, not a Buick turbo (yet).

One item that stood out from posts here is fitting of the main & rod bearings. The clearances need to be on the tight side. Run them loose like a SBC and they go away.

I think another area is the head bolt alignment. Apparently some blocks are not drilled and tapped parallel to the bores. This causes issues with clamping the head down.

Of course as for any turbo engine, the ring gap needs to be larger. And the piston to wall clearance needs to be set up for the added heat. A regular shop doing a rebuild may not even realize that 'little' 3.8l V6 is going to see 15 to 30 pounds of boost. And when not accounted for the engine doesn't hold up.

RemoveBeforeFlight

 

[Amelio]

Good points.....

I agree with the fact that the tolernces on these engines are tighter than an SBC but when I build an engine and maybe its just me I check all my tolerences with plastigauge and the proper specs....I have had engines break and 4 cams in this little V6 go flat but I know nothing was due to my work. I have never had a shop build one of my engines but I obviuosly send the blocks out for machine work. I heard that not all machine shops could properly prep these engines.

Yes these engines see lots of stree under boost but boreing, line boreing and other basic machine work is the same to me with this 3.8 or a big inch chevy.

I know lots of people put these engines together and trust that the machine work was done properly then they wipe a bearing and wonder what happened...

It could just be the voodoo of the Turbo 3.8 LOL

 

[gnxtc2]

The bearing clearances are set up on how you are going to use the motor.

If you set the clearances on the tight side, watch out. Tight clearances are less forgiving.

Billy T.
gnxtc2@aol.com

 

[2 QK 4 U]

I really can't add to anything that's already been said. I've built 3 including the one that is in my car now. It's been in service 4 years with no issues.

When the mains/rods are setup they need the proper clearances to maintain good oil pressure. And your machinist should bore the cyls to match the pistons with proper clearance. So use a machinist that has knowledge with the our engines.

 

[2 QK 4 U]

From gnttype.org

Rod bearing clearances - .0005 - .0026

Main bearing clearances - .0003 - .0018

 

[cool 84]

I went to a machine shop back in the late 90s to get a set up heads surfaced and saw a turbo motor in the shop. They were just throwing it together with the cheapest pistons and headgaskets they could find. The owner had the nerve to tell me that it would never make over 200hp and if it did the stock crank would break first. I think this is the attitude of a lot of shops. It's sort of like when me and my dad went to buy our first set of slicks for his GN. The store owner looked confused and asked why we needed slicks for a V6.

 

[BlackBandit]

As much as allot of people want to believe that building an LC2 is voodoo magic it's not. Just like any other engine it has it's nuances but it's still just an engine. There's alway going to be discussion about what works "best" but the info is out there. I can see a Chevy guy f'ing one up but I could also see a Buick guy f'ing up a small block. (assuming they had only built one or the other and just figured that's how you build an engine) Know your platform and you'll be fine. FWIW I think over the years allot of guys have just screwed up trying to build an engine when they shouldn't even have been changing head gaskets and rather than acknowledge that they didn't know what they were doing they chalk it up to it being a "special Buick turbo motor"

 

[usetaboost]

So use a machinist that has knowledge with the our engines.


Hell that's the truth. I get one hardcore race shop telling me my motor is "just like any other motor, doesn't matter if it's n/a or turbo, carbed or fi"
Then I go to el cheapo uh oh Reilley's and I walk in and get help carrying stuff out of the car and the guy helps me with the block and says "buick v6 huh?" I said YUP. Then I brought the crank in and gave it to him and he says "oh it's a turbo!" Guy was probably in his 50s. So I let him go to town on it. The motor didn't get the full monty but whatever wasn't right was made right and all tolerances were checked by the shop and checked by me. Everything was dead on from what they said. Gave me discounts beings I found out my uncle's brother's father's cousin works there . Next motor going there for sure, and so are a set of heads for them to work-I could care less if they have a flow bench with 2 knowledgable buick guys in there, a "relative" and I saw another turbo 6 in there when I picked mine up. Where the hell are all these area sioux city guys at???? Bugs the crap outta me!

 

[Blown&Injected]

From gnttype.org

Rod bearing clearances - .0005 - .0026

Main bearing clearances - .0003 - .0018

While those are the published Buick specs...Set up an engine anywhere near the tight side of those specs and the engine will die = period!

As mentioned, it is just an engine and anybody can do it. Just like any SMC, there are lots of things to look for and check - NO VODOO

 

[usetaboost]

I think my mains are .0010 and the rods are .0020 if I remember correctly. The 100 of the 200 miles I've put on my motor were WOT pretty much. The rest was from driving place to place. I hope it doesn't start knock 10 miles later when I get the car finished

 

[Alky V6]

As already mentioned, many tolerances and part specifications of an engine will change depending on the use of the engine. No matter what type engine you're talking about. If an engine builder recognizes that and takes the time to do a lot of research on the particular project at hand, he should be fine. It's finding that type of engine builder that's the hard part.

There are a wide variety of options that come into play as you move from building a 300hp street stomper to a 1,600hp record setter. Some of the knowledge that engine builders have learned have come about by learning first hand what works and what doesn't. It's called the school of hard knocks. Because of the expense of making bad judgement calls, I don't know that I would suggest that someone fresh out of auto shop should build a 1,600hp Buick V6.

 

[usetaboost]

That GN of yours still hot air? That sucker is quick!

 

[Alky V6]

That GN of yours still hot air? That sucker is quick!

No. It's not hot air any longer. The only thing stock under the hood is the radiator.

 

[Lee Thompson]

While those are the published Buick specs...Set up an engine anywhere near the tight side of those specs and the engine will die = period!

Sorry, have to challenge that statement. I run my rods and mains @ .001 with some of the rods a couple tenths less. Makes for good oil pressure. Just have to give it some break in time.

 

[Blown&Injected]

WOW, that is tight, but it is still 300% looser then .0003. I can't believe they even go there - that is like a press fit for a balancer