LT4 Hypertech + LT4?

[Skant]

I'm buying a Hypertech Programmer III for my LT4 because of a rear end change from 3.45 to 4.11. So I needed it for that purpose.

But as long as I have it... what do people think about their performance program on the LT4? I've searched the forums and see mixed reviews on the hypertech... some say its great, some says it's very little difference, and a couple even say it was worse than stock. (However, I think the latter had other mods to their vehicles where Hypertech specifically says that you should not use their enhanced programs if you've made alterations other than improved air box and exhaust... they even specifically list MAF changes (descreening or larger MAF) as something they won't work well with)

Hypertech actually has dyno charts on their site for the LT4 showing an 8hp increase (which sounds about right really). Interestingly, they have none for the LT1 which I think is where I hear people saying it made no real difference.

So it seems like since I have the programmer anyway... and all I have is an air rammer intake and borla exhaust... that should be ideal for their enhanced program... I aught to just put it on.

They do say it's for 93 octane fuel... or the best fuel available in your area... well, in the bay area here 91 octane is the best you can find. Will that present a problem? Nullify the advantages maybe?

Also... they talk about 160 degree and 180 degree thermostats to go with it. I may get one of these. On the forums I see some comments that 160 may be too low in cold climates. But I live in California. It should still be okay with 160 thermostat for smog?

I might buy the 160 degree thermostat and do the coolant bypass and thermostat at the same time.

Thoughts?

 

[Skant]

Just talked with Hypertech about the octane... they say the 93 octane is a must. If 91 octane is all that's available around California, I'll need an octane booster. Don't try to use their power programs with less than 93 octane gas.

Dunno if I want to carry around octane booster for each fuel stop...

 

[Skant]

Well, I got the Hypertech in and programmed my car. It's a nice device. Very easy to use. Takes it about 15 minutes to program the car.

I set it for 160 degree thermostat, even though I don't have one. So the fan settings are 185/192 now. And it seems to be able to keep the coolant in this range... at least for now. So maybe I don't even need the 160 stat.

Anyway, I programmed the car for Hypertech's power tune briefly and gave it a drive. It did not seem to cause detonation. And I might have felt a slight more power there somewhere, but any difference would really be too small to feel by the seat of your pants according to what they're claiming you'd get on an LT4 (8rwhp). However, since Hypertech advised me not to use their power tuning program on less than 93 octane fuel, I backed it out and am using the stock tuning.

At some point, I'll borrow a friend's G-tech meter or something and give it back to back tests on stock versus hypertech tuning. I just need some sort of nonsubjective way of measuring what it does.

Btw... if I do decide to go with it and use octane booster... gaining 2 points doesn't require much, I don't think. But do octane boosters really work?

 

[garycr14]

Hypertech

I've been using the Hypertech on mine for over a year on California gas. I do use an octane booster, I'm running AFR LT4 heads with slightly higher than stock compression. Make sure it is a potroliem based booster. I've been using about 1/2 bottle per tankful with no problems. I say use the programmer! Every little bit helps.

 

[Gman]

I was thinking about getting the programmer as well. I didn't know about the 93 octane requirement. We have 93 octane available but if it begins disappearing, I'm not sure I want to use a booster.

 

[garycr14]

Octane

I read the Hypertech manual, and what is say's about fuel is to use premium, 93 octane, or whatever is the best available. I used the Hypertech on my LT1 prior to putting on th ported AFR LT4 heads, and had no ill effects what so ever, without using octane booster. I started using the booster because with the mods on my car the compression is around 10.6-10.7, so the 91 octane is a little weak.

You might want to consider getting a custom program done on your computer, or a spare computer. Should be able to give you more noticable gains with proper programming.

 

[Skant]

Alright... I managed to borrow a friend's G-tech pro comp meter.

Since I didn't feel like going to jail, I did 0-60mph runs... well, actually to the top of 2nd gear... which is just over 60mph with the 4.11's on this car.

I did 9 such runs. 4 with the stock program and 5 with the hypertech program. I stopped after I had two good solid runs for each. I threw out all the weak launches (and I did note that I got wheelspin more easily with the hypertech program than with the stock program, which in itself indicates more power).

My best 0-60mph time was 4.373 seconds with the hypertech program. My best with the stock program was 4.558. This was 10PM at night... might get better hookup during the warm day.

0-60mph time is heavily effected by the efficiency of the launch. So my primary comparisons were the time delta between 60' and 330'. And the time delta between reaching 50mph and 60mph (which is the middle upper of my 2nd gear... no shifting and no wheelspin involved between those speeds).

Averaging out all of these delta times and expressing the difference as a percentage works out to a calculated increase of 14hp. Which seems to be quite inline with Hypertech's own dyno chart claim of 10hp increase on a totally stock LT4... whereas mine has most of the alterations Hypertech recommends as working well in combination with their program.

This testing is not extensive or solidly conclusive as to the specific amount of gain. But I am satisified that there is indeed a gain present. And it seems to be inline with the manufacturer's claims.


One thing this testing has done is make it very clear to me that I'm losing my 60' time to my tires. The car pulls a maximum of about 0.72g acceleration in 1st gear limitted by traction. The tires slip even after the initial hookup... a little too much torque for them being dished out by those 4.11 gears...

 

[LT4man]

I have one of the first Power Programmers that was built by Hypertech. In fact I am selling the Programmer. Worked great on my car until I did too many mods. Power was there and a lot smoother, too. Having the fans come on sooner really is a great idea. I have the 160 stat, but I also waited a little while before I changed the original stat. I live in Chicago and only park my car from December to March. Car heats up fine. The best thing about Hypertech is the fact that they deal with the whole RPM band and not just WOT.

 

[Kevin Doyle]

Skant tell me about your gear change cost any noises or vibration.Thanks Kevin

 

[Skant]

I had several other things done at the same time... I think just the 4.11 change was $1000-$1500 all told.

I am currently dealing with some sound issues after the change... however, at the moment it looks like it may actually be from worn out rear wheel bearings/u-joints. It looks like the switch to 4.11 may have just made the existing problem much more obvious. We'll know for sure once it's all settled here. But at the moment, it's looking like the new gears themselves are pretty quiet.

- Skant

 

[Kevin Doyle]

I had several other things done at the same time... I think just the 4.11 change was $1000-$1500 all told.

I am currently dealing with some sound issues after the change... however, at the moment it looks like it may actually be from worn out rear wheel bearings/u-joints. It looks like the switch to 4.11 may have just made the existing problem much more obvious. We'll know for sure once it's all settled here. But at the moment, it's looking like the new gears themselves are pretty quiet.

- Skant

Thanks for the info Kevin.

 

[nearmiss]

I had several other things done at the same time... I think just the 4.11 change was $1000-$1500 all told.

I am currently dealing with some sound issues after the change... however, at the moment it looks like it may actually be from worn out rear wheel bearings/u-joints. It looks like the switch to 4.11 may have just made the existing problem much more obvious. We'll know for sure once it's all settled here. But at the moment, it's looking like the new gears themselves are pretty quiet.

- Skant

HI Skant, You mentioned that you were looking at the Hypertech because of the switch to 4.11's among other things. Do you need to reprogram the ECM when you do a gear ratio change? ALso, did you find out about the noise?

 

[LT4BUD]

HI Skant, You mentioned that you were looking at the Hypertech because of the switch to 4.11's among other things. Do you need to reprogram the ECM when you do a gear ratio change? ALso, did you find out about the noise?

ECM needs to be reprogrammed to correct odometer/speedometer. Hypertech does this nicely.

They are $349 plus at Summitracing. I have a Hypertech Power Programmer III for the LT4 and it is for sale. I used it for my 4.10 gears, 160 stat, and power program. My new cam is beyond the Hypertech, thus it is for sale.