ok its go time now..

time to tune my car, eco motor, gm s/c, factory setup (for now, plan on going bigger later)

I have a guy willing to do the tuning for me, at a local dyno using hpt, downside, this is his first time using hpt, although he has tuned quite a few much more valuble cars in his lifetime...

or do i just take my spare ecu and get the gm reflash for a temp setup..

pros and cons?

anything i need to know if we go the hpt route?



** FOR SALE** http://www.j-body.org/forums/read.php?f=24&i=110879&t=110879

The GM tune runs a bit rich which gives some flexibility for running more power, ppl have gotten 240whp with it

Doing the fake 2 bar thing, even though you can tune it, its limited, i could never get the car to run right with it

I wouldnt trust a shop thats never used HP tuners much less one thats never done a "fake" 2bar tune, Id put that money to better use getting yourself a heat exchanger, pulleys, and a ported blower, dual pass end plate for the intercooler, water methanol injection. Heat is going to be your enemy alot worse than what fuel will be. Pretty much the entire cobalt aftermarket can be used.

Heres some links for parts you really should have running an M62
Dual Pass Intercooler plate Theres some various plumbing accessories you will need.

You can find 03-04 Mustang Cobra heat exchangers on ebay they are very effective they deliver 15-20IAT drop over even the stock heat exchanger thats on cobalts, heat exchanger is just a must with a Heaton Supercharger

A good water meth kit with a 150psi pump can be got for under 200 bucks, spray pre blower and its another 15-20 degrees under load reduction in IAT, dont let anyone give you crap about the rotors, you could spray raw fuel from a wet shot of nitrous into a Gen V heaton and it would be just fine, they dont use the same stuff the older 3800s did that had problems

I wouldnt go past a 2.7 or smaller pulley as that spins the blower past its max rpm and you end up making more heat than power, all the tools that use 2.5s are blowing up and wondering why

Supercharger porting Worth every penny and again delivers more of a drop in IAT



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

i have the heat exchanger now, Im about to go find the last little parts i need..

its not a shop thats duing the tune, we have access to a dyno.. they have hpt, so I assume they have used it before, but on what application? Couldnt tell ya

its a guy i know that works for mallett.. he spends all day tuning 700+ hp vettes... and is certified by gm to recalibrate their computers.. But as i said, that doesnt mean he can tune an eco with hpt..

I like the idea of using hpt, especially for the neat little aspects ( limiter, controlling cels, getting a real tune etc..)

but i also have less than a week to get this thing running, and a spare ecu.. maybe the gm reflash is the way to go for now?

bah, I am so lost





Edited 1 time(s). Last edited Friday, July 20, 2007 5:16 AM


** FOR SALE** http://www.j-body.org/forums/read.php?f=24&i=110879&t=110879

Since you have less than a week, here's one possible solution: Get the reflash for now, and it doesn't have to be on a spare ecu if you don't want it to be, it can be on the stock one. You can always get a spare ecu later and tune with hptuners on the spare. Either way will work, it's up to you. For information on how to use hptuners with the s/c, just check back on my How To post (which I saw you found already since you posted on it). As far as hptuners, I definetly think it's worth getting, maybe even worth it even if you don't tune with it. Here's a link showing how much I liked it and why months before I ever got to tune with it (Post #8 on page 1)

On another note, all the mods Rodimus Prime mentioned are definetly a good idea. The s/c definetly creates a lot of heat. It was actually HP Tuners that showed me just how much. I would see iat's (intake air temperatures) of over 230 degrees Fahrenheit, and that was with the stock pulley. Yes, 230, hotter than the ect's (engine coolant temperatures) should be! Granted that was in the summer, but probably only in about 90 degree weather. From there, I made getting the intercooler hooked up a high priority, and I was very impressed. IAT's dropped considerably and speed increased If you need help getting this set up, Phlatcav made some very nice posts about it, or you can ask me or anyone else that has it.

A dual pass sounds like a good idea too, but I haven't gotten around to that yet. Admiral Jedi did his successfully when he was running the s/c, so he might be someone to ask for more help, or I'm guessing there are people on the cobalt ss forums that could help.

As for the methanol injection kit, again something I would like, but just haven't gotten hooked up (although I do have most of the parts). I'm not sure who off the top of my head, but I believe someone made an alcohol injection FAQ one time.

As for the s/c spinning too fast, here's a little proof/equation for finding how out s/c rpms from a post i made a while back on another forum:

Quote:

RPM's are basically equivalent to a physics term of rotational speed, similar to angular velocity. Keep this in mind for later. Next, we know the diameter of the crank pulley (6.25"), the diameter of the s/c pulley (whatever you want it to be), we can throw in a given engine RPM. Somehow with that information and the fact that the crank drives the s/c using a belt, we need to find the s/c RPM.

Since it's a belt driven system, we know the belt will have the same tangential, or linear, speed everywhere. This also means that the pulleys at their outter edges will have the same tangential, or linear speeds. So, we can set their linear speeds equal to each other...v1 = v2...but that doesn't do us much good as it stands. That's where another equation comes into play...

v = omega * r

or in english... velocity(linear) = angular velocity * radius.

so we can now replace each v with an omega * r....

omega_1 * r1 = omega_2 * r2

Note: the equation says to use the radius instead of the diameter. However if you notice, converting to the diameter would be multiplying each side of the equation by 2, so nothing is changed. so....

omega_1 * d1 = omega_2 * d2

omega_2 is the rotational speed of the s/c pulley, which is what we want, so solving for that we get...

omega_2 = (omega_1 * d1) / d2

Now, let's use values from one of the previous posts..7,400 Engine RPM's and a 2.5" pulley.

so s/c RPM's = (7400 * 6.25) / 2.5 = 18,500 RPM's.
So, that's a little proof if anyone's interested.

A clarification:
It was talked about a little in the rest of that post, but pi (3.14159...) would be involved in the equation as well. However it cancels out on both sides of the equation so I left it off. If you notice, I substituted RPM's in for omega. In reality omega is supposed to be in radians (a measurement of angle from 0 to 2 pi) per second. However, since there are 2 pi radians in each revolution, you could just multiply the rpms by 2 pi and then divide them by the number of seconds (convert from minutes to seconds). However the 2 pi's will just cancel out by dividing them on both sides, and the seconds will cancel out by multiplying them on both sides (since they are in the bottom of the fraction). So after all that being said, you can just end up leaving it in terms of RPM's.

If you have any more questions, feel free to ask.

John02 wrote:
On another note, all the mods Rodimus Prime mentioned are definetly a good idea. The s/c definetly creates a lot of heat. It was actually HP Tuners that showed me just how much. I would see iat's (intake air temperatures) of over 230 degrees Fahrenheit, and that was with the stock pulley. Yes, 230, hotter than the ect's (engine coolant temperatures) should be! Granted that was in the summer, but probably only in about 90 degree weather. From there, I made getting the intercooler hooked up a high priority, and I was very impressed. IAT's dropped considerably and speed increased If you need help getting this set up, Phlatcav made some very nice posts about it, or you can ask me or anyone else that has it.

so i can actually use HPT to datalog with the gm reflash? will it actually show me IATs, timing, etc? i've heard a bunch of mixed answers on that one. some say yes, some say no. If the answer is yes, I'll be picking up HPT in a few weeks then.

well i already have a spare ecu.. and I got everything wired and plumbed for the intercooler / heat exchanger today..

I am going to get the car flashed at the dealer ship on monday... I'll worry about hpt at a later date when it is more nessisarry

thanks for the input guys



** FOR SALE** http://www.j-body.org/forums/read.php?f=24&i=110879&t=110879

alias1429 wrote:

John02 wrote:
On another note, all the mods Rodimus Prime mentioned are definetly a good idea. The s/c definetly creates a lot of heat. It was actually HP Tuners that showed me just how much. I would see iat's (intake air temperatures) of over 230 degrees Fahrenheit, and that was with the stock pulley. Yes, 230, hotter than the ect's (engine coolant temperatures) should be! Granted that was in the summer, but probably only in about 90 degree weather. From there, I made getting the intercooler hooked up a high priority, and I was very impressed. IAT's dropped considerably and speed increased If you need help getting this set up, Phlatcav made some very nice posts about it, or you can ask me or anyone else that has it.

so i can actually use HPT to datalog with the gm reflash? will it actually show me IATs, timing, etc? i've heard a bunch of mixed answers on that one. some say yes, some say no. If the answer is yes, I'll be picking up HPT in a few weeks then.

That is correct, you can use HPT to datalog with the gm reflash, IAT's, timing, fuel trims, knock retard, tps, O2, commanded AFR (and other commanded items), trans fluid temp, and all the basics of course just to name a few. plus you can set up custom ones based on other sensors such as AFR error, and you can have 0-5v inputs as well (needed for widebands). I can send you a better list, or screenshots if you want.

John02 wrote:
That is correct, you can use HPT to datalog with the gm reflash, IAT's, timing, fuel trims, knock retard, tps, O2, commanded AFR (and other commanded items), trans fluid temp, and all the basics of course just to name a few. plus you can set up custom ones based on other sensors such as AFR error, and you can have 0-5v inputs as well (needed for widebands). I can send you a better list, or screenshots if you want.

no need to send screen shots. i just wanted a definite answer from someone thats actually datalogged the reflash with hpt. thanks for the info, i'll be ordering hpt next week