GM crate engines?

[Christian Steffen]

TBI can take the 383, and self adjust just fine.. I imagine vortec computer can do the same. You don't need a tune.. your computers do that on their own. That's why you have an O2 sensor. The "tune" part, is telling the computer to handle what it sees differently. More timing, more fuel, etc. The factory original tune is the "safe" tune. GM does that for warranty reasons, and frankly, extends the life of your motor. There's allot of "performance" left on the table with all the C/K motors. Anyway, so long as your injectors and fuel pressure can keep up, the computer wont get scared.

The computer can account for some of the changes via the o2 sensors, the MAF helps a lot too, but that doesn't mean you should just ignore the computer when making large changes. The o2 sensors only work around stoich, what happens when you enter PE? LTFT's don't carry over into PE mode with the black box AFAIK, so you WOT fueling will not be corrected by the o2 sensors.

What if you greatly increase your CR? Stock timing tables might not be safe anymore even though they are quite conservative.

Yes a stock tune will work fine for minor changes, but you will be leaving power on the table. Hence if you're spending 5k on an upgraded engine, spend the extra money for a tune.

 

[s98gmc]

The computer can account for some of the changes via the o2 sensors, the MAF helps a lot too, but that doesn't mean you should just ignore the computer when making large changes. The o2 sensors only work around stoich, what happens when you enter PE? LTFT's don't carry over into PE mode with the black box AFAIK, so you WOT fueling will not be corrected by the o2 sensors.

What if you greatly increase your CR? Stock timing tables might not be safe anymore even though they are quite conservative.

Yes a stock tune will work fine for minor changes, but you will be leaving power on the table. Hence if you're spending 5k on an upgraded engine, spend the extra money for a tune.

My stock 350 Vortec put another 20 horsepower to the wheels with a tune. I can't imagine skipping it after the expense of buying and installing an upgraded crate engine.

 

[PlayingWithTBI]

The computer can account for some of the changes via the o2 sensors, the MAF helps a lot too, but that doesn't mean you should just ignore the computer when making large changes. The o2 sensors only work around stoich, what happens when you enter PE? LTFT's don't carry over into PE mode with the black box AFAIK, so you WOT fueling will not be corrected by the o2 sensors.

What if you greatly increase your CR? Stock timing tables might not be safe anymore even though they are quite conservative.

Yes a stock tune will work fine for minor changes, but you will be leaving power on the table. Hence if you're spending 5k on an upgraded engine, spend the extra money for a tune.

X2

 

[Tachyon]

Yeah, "Do I need a tune?" and "Will I benefit from a tune?" are two entirely different questions.

You can do a LOT before you need a tune. But you can benefit a lot from a tune even if you've done little else.

In the case of the HT383E swap, even GM suggests a tune to wake up the power hiding in this system.

I added a cold air intake, headers, freeflow exhaust system and performance cats, and a tune. The difference from "stock" (IE just the engine swap) was huge. Now, one those rare occasions when I remove the tune to take it to the dealers etc, I really notice the difference in performance.
But mainly, the biggest thing is that those things together add up to way more than the sum of their parts. It's about the system as a whole.

 

[GregB]

I ordered the 2 bolt main engine for my Tahoe. PIcking it up Saturday in Montana and it will be installed next week.. I just couldn't justify the price diff to the 383E. Im in Canada and the best price I could get here in Saskatchewan was 4100 plus taxes of 11%.. At 1999.99 US and even with paying the rip-off 37% exchange rate the engine cost me 2750. Canadian. About 200.00 to go to Montana to get it and the 11% at the Border which brings it to about 3200.Canadian . I saved about 1300.. getting it from the USA. Still trying to fugure how that dealer can sell that engine for 1999.99 and ship it from Lubbock Terxas to Plentywood Montana for free and still make a profit..

 

[Christian Steffen]

Yeah, "Do I need a tune?" and "Will I benefit from a tune?" are two entirely different questions.

You can do a LOT before you need a tune. But you can benefit a lot from a tune even if you've done little else.

In the case of the HT383E swap, even GM suggests a tune to wake up the power hiding in this system.

I added a cold air intake, headers, freeflow exhaust system and performance cats, and a tune. The difference from "stock" (IE just the engine swap) was huge. Now, one those rare occasions when I remove the tune to take it to the dealers etc, I really notice the difference in performance.
But mainly, the biggest thing is that those things together add up to way more than the sum of their parts. It's about the system as a whole.

Need is relative. If the need for tuning is just at the point where the engine wont run or the engine self destructs without a tune, then yes the "need" for tuning is greatly diminished. Personally I move the line much farther back, but to each their own.

Otherwise i agree with what you're saying, the entire system needs to be considered.

 

[df2x4]

Those of you who say you're running non-stock engines without a custom tune, are you monitoring your air/fuel ratios at all? If not, I'd really recommend checking them. I can tell you from (expensive) experience that even if the vehicle seems to be running fine, your air/fuel ratios could be way lean. Lean under load is bad, like melt holes in stuff bad. Personally I can't see the logic in dumping thousands of dollars into an engine and then running it with non-optimal air/fuel mixtures which could result in premature wear.

 

[Owenst7]

I installed the 4 bolt (GM 12681431) in my DD in 2015 IIRC. The original engine had 230k on it and the lower intake manifold seal failed (The dealer told me they were installing the correct one at 20k).

The original had 2 bolt mains and I didn't see need for the inconel seats upon inspection of the heads (found cracks in both though). I just wanted the tougher engine since I'll be keeping that engine long enough to rebuild it some day.

The long block went in without a hitch and I'm at 265k now. Runs just like the first engine did when it was new.

The Mac's engine leveler w/ adapter for the L31 works freaking awesome. Fit like a glove.

 

[PolyMatt]

What is a good reseller or company to purchase reliable l31’s from? Good price too


Sent from my iPhone using Tapatalk

 

[letitsnow]

What is a good reseller or company to purchase reliable l31’s from? Good price too


Sent from my iPhone using Tapatalk

I bought mine (new GM) from Speedway Motors. All went well.