I was wondering. we wont debate over the "GMS2 + 2.78 pulley - it is safe or not". That has gotten pretty stale and I bet even heated discussions over it....LOL

What I want to know is if I add 60lbs inj. to my GMS2 and 2.78 pulley will that run safely without changing the GM Stage 2 reflash?

 

No it won't run right. The pulse on the injectors are different.

 

I think you need to tune for the new injectors

 

Have to tune it for the right injectors, might as well go with a 2.6-.7" if you are going that route.

 

What everyone else said, tuning is required.

 

has anyone done it? what was your A/F ratio? I know I wont have the best power, but could it be safe?

I am getting 60lbs'ers and currently have GMS2 with the 2.78 pulley. I plan on getting HPT's as well. thought maybe I can run this way till I get it. PERHAPS that is why I am asking. I hope to hear someone has actually tried it and rather than I think it needs a tune or the all over powering "YES IT NEEDS A TUNE" with out an explanation.

If you have tried it, someone, then say so. and tell me what you found. thanks.

 

You try it and tell us what you find....because I don't think anyone on here has enough guts to do that because it would be stupid....no offense, I bet you that you would damage the engine...but try it out for us

 

lol.... The dealer had me install my GMS2 on stock tune. drive it 30 miles on a highway so they could flash it. no damage. putting on 60lbs at most would at more fuel but since I am running with a 2.79 pulley the theory is that is may balance it out.

but you are entitled to your opinion. and I dont have one. I am not judgemental about it. It was a idea and I thought maybe someone did it already.

thanks for e1s input. later.

 

It would run really rich which could cause fuel to build up in the cylinder and possibly leak past the rings, breaking down the oil and destroying the bearings and other improtant parts that require lubrication.

The 60's require quite a bit of tuning unlike the 42's since the computer is not designed to run anything larger than 42's. You have to tweak the MAF, VE tables, timing tables, spark dwell, and more to get them to run properly.

 

If it was that rich the car would not run. impossible. and you would see black big time out the back it is was really bad and could possibly run.

I not going to do it unless someone says it can be done. the next thing I would do is to do two or three dyno passes with A/F monitoring to see where I am at. the other thing I would do is purchase a wideband.

personally I think the first thing that would be damaged is the Catylitic. But what ever, it is not safe and the car cannot be run this way. thanks

 

I'm not saying this to be an ass, but it would run. Not the greatest, but it would run. My Dad actually ruined a motor as a teen by using Holley 750 double pumper on a stroked 283 small block. The oil thinned enough that the moving parts actually started to touch and wear.

You were talking about using the injector with a tune set up for 42# injectors, you would be getting approx 33% more fuel then you should be. I was just trying to help explain that it was a bad idea. I'm sure your cat would suffer pretty bad in that scenario, but it's cheap and easy to replace compared to tearing down and rebuilding an engine.

I'm just trying to be helpful and save you the money and trouble of running the car improperly tuned. I'm not on the attack, just trying to help.

 

First off, I dont think anyone is attacking me but helping me. seeing if it is worth a try and what the dyno does. thought the PCM may sense that it needs to cut back on fuel as it is running to rich therefore making the injector pulse shorter. that is what it does moving from cold weather to warm weather. Our fuel economy goes way down when we hit -20F. the engine sense what it needs automatically which is the beauty of fuel inj and PCM controlled. It is technology that is embraced by snowmobile and motorcycle enthusiates as they no longer have to spend big money on jetting and balancing carbs for all cylinders.

I ran a 355 chevy small block with a Holley 750 double pumper. no problems. Yeah it is possible to get gas in the crank but that usually happens on a cold no start day and the owner keeps trying till the battery is dead. I still would find it amazing the car would run with raw fuel going in like that. you need a certain ratio a/f ratio and the fuel to be vaporized to run. raw fuel with little air and a small spark just does not go.

The whole Idea of this post was to find someone who said "yep, I thought of it, dynoed and check a/f and it was bad" or "it was not bad but it can be better, then hp tuned".
you know some real experience for trying. I mean come on. I sure someone bought a pulley, 60lbs'ers, hptuners, put it all on and the car ran. then they logged 30 mins and then went on to tuning it. If it did not run or poured fuel in with risk of screwing the engine I am sure we would have heard that one. you have to start somewhere when you get this set up.

 

Seriously, do not run the 60 lb/hr with out a tune. For like 30 min to go get a tune... maybe, but your going to run soo rich that the fuel trims will max out, leaving you rich even after it learns, and that will also cause a CEL. It's just a bad idea, always get a tune with new injectors period. Things like pulley swaps can be ok with out a tune, but injectors are NOT something you can get away with changing like that.

 

Most people with 60lb would flash first befor they start. It is just safer. I really do not think the car would run too well at all with 60 2.79 and no tune. But hey if some one did and found out what the IDC is along with the A/F then that would be nice to see since most of us will go to the 60lb.

 

There is no way that the IDC would be anywhere near correct, it's just how the system works. The ECM has a chart to know how much fuel is being flowed at all times, and it would be nearly 50% off. Meaning it would be flowing %50 more fuel than it needs to, that's a SCARY amount. Please, no one try this. You will flood your engine!

 

Now we are getting somewhere with explanations, some what. thanks.

Flash with what? what tune are you starting with? can you expand on that?
In case you didnt notice the car has a GMS2 tune.

SO if I get the 60lbs and HPtuners then what are the things I would do before I start the car? I would have thought I would have to start to get a baseline of info to work with?

 

Read my explanation as to WHY not to just swap injectors with out a 'tune'

Here is what you do if you have HPT. Install injectors, take the stage tune and increase the 'injector flow vs kPa' chart by calculating the flow for the injectors you have.

Now don't take offense to what I say next, because it is not meant to do so: If you are asking questions like these, you need to research on your own more before doing this. Yes, you can still do it by asking and having someone walk you through it, but if you don't LEARN how and why, then do not do this by yourself, as you can really cause problems if you do not know what you are doing. This happens way too often, and then everyone whine on how 'The LSJ sucks/blows up pistons/falls apart/blows head gaskets/unmoddable'. It's not that the engine is hard to mod, just that people try to mod it with out understanding it, and then whine when something goes wrong.

My suggestion to you: Go to www.hptuners.com , go onto their forums, and read as much as you can, download the user manual, and learn what it takes to tune the car.

It's good to know that you want to know why people are giving this answer, that shows that you at least want to learn!

 

you need a custom tune to run the 60 lbers

 

I would not put 60lb until I get my PMC flashed by TAG and they used HP along with other software to come up with the good tune with the 60lb and 2.79. So this is the best practice for the engine. If a good tuner installs the 60lb and then goes on line and talks to HPs fourms to find a good starting point to tune from. Then from there they would feel better then just starting from scratch. Another method would be to do some math and calculate the IPW and other setting and then start from there. This would be a lot better then just installing the 60lbs and seen what happens. That might be good for tigger but not most people with a brain.

 

You definetly can use the stock tune as a 'starting' point. The only thing you need to do is change the 'Injector Flow vs. kPa' chart to accommodate the new injectors, and then log and tune from there. You can't get tuned WITH out the change either, they must be done at THE SAME TIME.

 

That is what I am saying. You are just being more spacific. Cool. I was just making a point that it is not good to start from scratch. You need to make a change befor you start running and tuning. Ball parking a system before you turn it on is always a better idea then just starting from scratch.

 

Not sure what you mean by 'starting from scratch'. There is no starting from scratch with HPT, you have to start with SOME tune from SOMEWHERE, usually what ever you pull off the ECM is what you start from.

 

No what I mean from starting from scratch is starting with no adjustments at all and no HPt at all. Just put the 60 and 2.8 on and start up with a normal stage 2 flash. That is what I mean from scratch. No tune at all.

 

$1 to the person who throws 60lbs on a stg 2 car and gets a vid of them TRYING to drie around

 

well, there is a 'tune' just not a good one for the setup!


And Dan, I agree! I started up my car once when the target AFR was set wrong on my LC-1 and HOLY **** did it get REALLY pissed off. No way it was even rolling down the drivway like that.