Thread: Thinking of buying a spare. motor to build

Originally Posted by ADecker

I have heads and and ST5 in my basement, along with a double roller. Head studs on the way then the 600+ wHP fun begins.

Git-R-Dun

GTP rods are stronger than NA rods, gtp crank is better as well, we used gtp bottom end and put diamond racing dished pistons with a t66 up top on my buddies impala.

the gtp rods are stronger for sure, it was an NA block.

Also for reference we had done a quick fun run and my Z28 was a mid 11 second 1/4 daily driver and the impala put buss lengths on me and he had subs/box/tools/full interior... Since the car never ran at the track our best estimate is it was at least a mid 10 second car.

Originally Posted by ls1adam84

GTP rods are stronger than NA rods, gtp crank is better as well, we used gtp bottom end and put diamond racing dished pistons with a t66 up top on my buddies impala.

the gtp rods are stronger for sure, it was an NA block.

Also for reference we had done a quick fun run and my Z28 was a mid 11 second 1/4 daily driver and the impala put buss lengths on me and he had subs/box/tools/full interior... Since the car never ran at the track our best estimate is it was at least a mid 10 second car.

GTP crank is the exact same crank as the NA crank. Rods are made of same materials.

Originally Posted by ADecker

I have heads and and ST5 in my basement, along with a double roller. Head studs on the way then the 600+ wHP fun begins.

Originally Posted by Scottydoggs

JUST NO! like said earlier, dont touch the bottom end. or you'll just waste it. thats called a 200 mile engine.

your also gonna want a way to tune it when done. it should run on a gtp stock pcm, but a tune will help it out.

Question: What the hell? Why do people have issues building a short block? I don't understand. I have built everything from Briggs and Stratton and other small engines, 2 cylinder 2 stroke Rotax, Lycoming I/O 360, LS1's, several Chevy 350/383'sQuad 4, Ford 3.8 SC, 3.1/3.4's and never had any issues with an engine coming apart. Not to say everything has gone perfectly, but come on a 3.8 Buick? What's the deal? Not trying to be a smart ass or anything just seems really odd that messing with a bottom end would be a 200 mile engine unless you do like my dad did on a VW engine and torqued the mains and rods without using a torque wrench and seized the engine after about 5 miles that was in the early 70's when he was becoming an aircraft mechanic in the Army and thought it's just a car engine it doesn't need to be held to the standards that aircraft do.

Jeff

Don't want to go with a turbo yet I'd like to stay with my blower to c where I stand with the guys round here

Originally Posted by J57ltr

Question: What the hell? Why do people have issues building a short block? I don't understand. I have built everything from Briggs and Stratton and other small engines, 2 cylinder 2 stroke Rotax, Lycoming I/O 360, LS1's, several Chevy 350/383'sQuad 4, Ford 3.8 SC, 3.1/3.4's and never had any issues with an engine coming apart. Not to say everything has gone perfectly, but come on a 3.8 Buick? What's the deal? Not trying to be a smart ass or anything just seems really odd that messing with a bottom end would be a 200 mile engine unless you do like my dad did on a VW engine and torqued the mains and rods without using a torque wrench and seized the engine after about 5 miles that was in the early 70's when he was becoming an aircraft mechanic in the Army and thought it's just a car engine it doesn't need to be held to the standards that aircraft do.

Jeff

Because on these motors, once you take the main caps off and pull the crank the block twists. You need to line bore the block to be sure it is straight before you reassemble everything or it won't last. I'm sure there are some other things that need to be done but this one is for sure. Can't be done like your average smallblock chevy.

What's a "blown motor" is that thr same as "it's broke, it don't work". Come on guys there is no technical discussion on these issues it sounds like a bunch of kids that hear something from one or two sources and take it as gospel. I'm interested in root cause analysis not conjecture. This is the technical discussion area correct?

if I remember my 3.8L history correctly the Ford 3.8L is a copy of the Buick 3.8 with a few changes. So you mean to tell me that Ford can make a better copy than GM can make original?

Jeff

Thank you Redcompg, that's a much better answer. But I would still like to know what failure modes they have seen. So what makes this any different from the 3.8 Buick engine used in the grand national and regal T type?

regarding the Ford 3.8, yes the head gasket monster is alive and well on those engines, though my 95 Taurus has 175k and been a great engine. My Tbird was a PITA, but running 13psi bone stock with a restrictive exhaust isn't helping along with Aluminum heads and most people's lack of being able to properly bleed the cooling system. We used copper then Comitec (sp) head gaskets and they are much better than the originals. Currently there are several under 10 second cars on the forum and at least 14 that are 12 or under. It's not a bad engine if you know what you are doing. Aluminum headed, sequential fuel injected supercharged AND intercooled from the factory in 1989 no less.

The main reason these engines fail during rebuild is people neglect the fact that if you take out the crank, you have to have the block checked for proper straightness on the crank journals due to the design of the crank main caps. Over a period of heating and cooling cycles, the block wants to "warp" and the only thing keeping it from doing that is those caps. You can put rod bearings in all day long as long as you pay attention to the production date on the block (you can't put rod bearings in a 95 block...the thickness is wrong...I've measured this on multiple early block 3800.) If you have a block dated year 97 and up, you can put rod bearings in as long as you measure properly...and I'm not just talking plastigage...the rod journals and the big end of the rod must be measured as well. Good luck with your rebuild.

Sven,

That at makes more sense. Basically it boils down to improper attention to detail. I'm not new to engine building so I do understand proper procedures. I just think that in the technical forum should have higher standards. Discussion from knowledgeable people about the subject in question. You have a guy that wants to know manifold air temp which I think is a valid question and I would think that as long as these cars have been out you guys would have all kinds of data. There isn't, he basically gets laughed off the board. When you are trying to get the most out of any engine you need to know everything going on. Guessing is grenading is what I like to say.

I'm not planning a rebuild. If got to figure out why it's not running right first. (Suspected Knock sensor)

Jeff

Originally Posted by Sven The Baldman

GTP crank is the exact same crank as the NA crank. Rods are made of same materials.

Sorry I realized I did not specify, we used the crank and rods from a gen 3 gtp. Although I think there were some differences between 2004 to 2005. I apologize for that I guess that's what I get for sitting here at work with 4 tasks to do and trying to read stuff here, I am getting too old for this multi tasking crap.

Originally Posted by ls1adam84

Sorry I realized I did not specify, we used the crank and rods from a gen 3 gtp. Although I think there were some differences between 2004 to 2005. I apologize for that I guess that's what I get for sitting here at work with 4 tasks to do and trying to read stuff here, I am getting too old for this multi tasking crap.

Yeah, that was the series 2/series 3 changeover. However the only thing different still was the rods...they went from cast to powdered metal. Cranks remained the same for gen 2 and 3 though.