Our LNF turbo upgrade ECM has fuel pressure logging capability.

But yes, that is for the DI rail.

 

Good stuff. Through TF or HPT? I never really desired to log it much, when i was on the stock turbo, so never really tried.

 

I built a custom PID and added it to the table & chart in HPT... Fuel Pressure (psi) hopefully I can log it. I know Vince told me ups the pressure setpoint >160% load. I really would like to get this thing on E85, mixing 1:1 pump gas & E85 is getting old. We'll see.

 

Gotcha, lemme know what works for you! I tried setting up a PID, but IDK... I suck at custom PIDs. Took me a week to figure out how to log boost beyond 22.5 (before it was the cool thing to do).

 

Set up a simple custom pid...=[SENS.34.psi], nfg, came back as unsupported parameter. Oh well. It's in the sensor list but apparently got lost in the translation.

 

Agreed. Alcohol loves the slow rich burn a lot more than gas so provided there is no knock it should not be a big issue.

 

Question for you ZZP guys. Why not go back to LNF trans for better gearing, and swap to the 6 speed?

It will balance all the gears, and bring 4th out of overdrive and actually make it useful.

Is it simply because of the cost?

 

I'm not sure what you mean by going back to the LNF trans and swap to the 6 speed.

Honestly, this trans is great. Driving around town, it feels much better. With 24.5" slicks, the gearing will be great for the track. Sure 1st could stand to be taller, but I still put down a 1.71 sixty foot having to shift in that time. It must not be hurting the short time too bad.

 

When you go back to the larger turbo, the LNF 3.82 will give you a better powerband. Then toss the Quaife 6 speed gear set in. Will balance out 1-2 and now your 4th won't be an overdrive.

This would give you a lot better time at the track. Didn't think you guys ran a 24.5" slick, though.

 

I guess if the Quaife setup was affordable, you would be making a good point. Then again, you wouldn't need to, because we would already be running it.

I'm not running 24.5s, but should be on the stock turbo.

FWIW, though, the 3.82 will not do anything to help the larger turbo perform better.

 

I only mention it because with these large turbos some of you guys are running, the 4.45 has be to hurting your spool/powerband by a decent amount.

But I figured you guys did it so you can use 4th gear more and cross traps at top of 4th. Instead of shifting right into 4th then letting right out at traps. Wasting a shift.

 

As I added in to my post above- the 4.45 diff is not hurting times. I would say it is the opposite. The 4.45 makes the larger turbo perform better. The only way it would hurt performance would be if I shifted extra slow and couldn't afford to add another shift.

The added benefit to the 4.45 is that the trans holds up much better as well.

 

Since the 4.45 is a higher gear, it helps lessen turbo lag, because the engine is revving faster. A quick shift won't drop boost, and IDK if you have seen Matt M drive, but he can drive!

 

Lol, that isn't how gearing effects Turbo spool. But okay.

I won't argue against time slips. Obviously whatever you guys are going, works. You have all the records for a reason. But I just think you could improve those times even further with different trans-axle setup. However, spending 3k+ on a gear-set isn't exactly practical and most likely not worth the money.

 

Cool story brah. What's your theory then? Throw in a higher gear and let the engine bog to death?

 

If you already don't understand how it works, then you probably couldn't comprehend it anyway.

 

Lol, ok. If you say so. Way to contribute to the worthlessness of holding in secrets (aka css).

 

Lol wow, it's not a secret... It's Car Modifications 101. Cobalt's aren't magical machines where basic car knowledge differs from any other car.

 

So, I am right. Ok. Lol... you don't know me, so don't be so quick to discredit my knowledge. Thanks.

Think about it, the faster a motor revs, the faster the exhaust gases are created and evacuated. Turbo is spooled by exhaust gases, so the quicker you get more exhaust out the tail pipe, the faster the turbo spools. But, to get exhaust out the tail pipe, you have to rev the motor. Higher gearing revs the motor faster, hence creating exhaust gases faster. Its simple knowledge. Now, present your point, please.

 

With a shorter gear you are putting less load on the motor = less spool.

With a longer gear like the LNF 3.82, at any given point in the RPM range, the motor will see more load and will be in that RPM range longer. So the turbo will see more exhaust from the extra load/time and spool faster.

If you don't believe. Search any Mustang forum for example and see what gearing all the Turbo guys run. Also read them talk about it.

If you still don't believe. Go dyno a large turbo car in 1st gear, then in 4th. Then come back and tell me gearing doesn't effect spool.

 

Also, why else do you think GM went from a 4.05 final drive to a 3.82 when they went Turbo? For the fun of it?

 

This is true to a point, but I really don't see the difference between the 2 being that great. Its all a balance of gear ratios here. What works in a Mustang, won't necessarily work in the Cobalt. Sure, the theory is there, but notice the mustangs don't run a 3.03 gear. They run a 4.10 instead of a 4.70 (for example, IDK what ratios they really run). Too low of a ratio, and the motor will bog, like I said up there ^ . Bog is not our friend.

And GM went to the lower gear for a number of reasons in the LNF. It wasn't for drag racing, thats for sure. It compliments the rest of the ratios better, and it is a better cruising gear. Ever notice that the LNF will get alot better fuel mileage than the LSJ?

But, were both arguing valid points, its just finding, and proving, which point is most valid here.

 

You are both right in some regard, and wrong in others.

They went to taller gears in the LNF because it makes a lot more torque than the LSJ. The short gearing is not needed or beneficial for anyone running street tires and a stock turbo.

As far as taller gears spooling a turbo better- yes that is true from an RPM standpoint. Taller gears will get the turbo spooled at a lower RPM than shorter gears. However, you obviously don't need the turbo to spool at a lower RPM when the shorter gears put you at a higher RPM.

Also, the Mustang guys that you are referring to are most likely running automatic transmissions. In that case, both cars will be at or near the same RPM based on the torque converter. Now the taller geared car can take advantage of the greater load off the line without the disadvantage of lower RPMs. FWIW, I run a 2.93 trans in my Grand Prix along with 28" slicks, and it works well for me. If it was a manual trans, this wouldn't work so good.

 

Thanks for clearing that up Matt. I am thinking more from a mechanical diesel standpoint, I think, where the more exhaust, the more fuel, the more boost, the more power. But, can ya blame me? Been working on this damn diesel for the last 6 months, trying to get it going before winter!

 

I assume you mean launches? Because final drive doesn't change shift points or gear ratios between gears.

I only mentioned Mustangs cause two of my buddies have S197's and both looked deeply into going Turbo. The Mustangs I was talking about are all manuals. For instance, all the N/A and Blower guys use short gears such as 4.10+. But all the turbo guys go down to a 3.27/3.55 set. You will see all the top10 turbo cars are all tall gears. Like I said, I only mention Mustangs cause I know a good bit about them since I work on them. Would be the same for any car, FBody, Hondas, 240s, etc...

This is all mute point since you are back on stock Turbo. K04 spools so fast, gearing doesn't really matter. But once you start getting into the 600+ range with large turbos. Could be the difference between a 9 and 10 second run.