When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I am new to the Forum and I am so glad I found a place where we all can share and talk about our passion :-)
Without any further due, I'll get to my topic...
I installed the following on my 2015 C7 Z51 A8:
* Halltech Cold Air Intake
* 103mm Nick Williams Throttle Body
* MSD Intake Manifold
* Straight Piped - No cats, no resonators, no mufflers
* DSX E85 Flex Fuel sensor
* RX Performance Catch Can
Once I installed everything, I took it to the reputable tuner for the first dyno tune ever. So "Stock" numbers, I don't have unfortunately, but the Dyno sheet is attached and here are my concerns:
As far as I know, these LT motors make way more Torque then Power... either way on 91 or E85... So how come these results?
1) The car made almost the SAME amount of Power as Torque on 91 Pump gas...?
2) Then the switch to E85 gained 33 whp and ONLY 13 Torque??
3) The tuner has a DynoCom, which he mentioned reads lower number compared to a DynoJet... More like a Mustang Dyno. With that being said, it seems that overall even if I add 5% to numbers to match DynoJet numbers... overall results (hp & tq) seems to be a little on the low side of things...
4) What's that small dip around 5k rpm on pump gas 91?
I would like to get your opinion guys as it really baffles me...
Thank you for any assistance as I would really appreciate any input from you guys!
Warmest regards,
Last edited by BigMuscles91; 02-28-2019 at 09:43 AM.
I wouldn't worry too much about Dyno numbers. There all over the place from 0-30 hp. Run your car in the 1/4 mile in then you'll see the difference the mods made. The numbers don't seem that low considering you don't have headers. My car only dyno 426 hp / 436 tq with a tune, Mid lenght headers, two hi flow cats, X-pipe w/o cats, ported Int manifold & throttle Body.
I wouldn't worry too much about Dyno numbers. There all over the place from 0-30 hp. Run your car in the 1/4 mile in then you'll see the difference the mods made.
The numbers don't seem that low considering you don't have headers. My car only dyno 426 hp / 436 tq with a tune, Mid lenght headers, two hi flow cats, X-pipe w/o cats, ported Int manifold & throttle Body.
I see what you mean, however even you have higher TQ number then your HP and that what throws me off... Knowing that there is more Torque left out there that can be utilized will definitely yield more power to go along with it.
Since Torque creates Power and not the other way around...
We would all be speculating without seeing a log from the dyno run or a log from you out on the street at WOT. Alot of tuners that don't tune the LT platform much have issues with keeping the throttle open because of all the torque management stuff.
Did you install all these parts and then take it to a tuner to tune? Sounds like you did?? I bet the tuner just didn't throw all he has at it and it left the shop with moderate timing and fueling and such. A tuner that didn't build the car isn't going to spend a whole lot of time tuning a car.
As others have said though. Don't chase a number. If the car feels good that's all that matters.
I see what you mean, however even you have higher TQ number then your HP and that what throws me off... Knowing that there is more Torque left out there that can be utilized will definitely yield more power to go along with it.
Since Torque creates Power and not the other way around...
You didn't mention if you have Headers. That could probably be why my TQ is slightly higher. Again though, try not to get caught up in the numbers. My C6 LS2 N/A Heads & cam, Ported Fast I/M with 4.10 gears Dynoed 512 rwhp, and only 436rwtq, but I manage to run 10.48 @134.08 mph in the 1/4 mile, and consistent 10.50s.
We would all be speculating without seeing a log from the dyno run or a log from you out on the street at WOT. Alot of tuners that don't tune the LT platform much have issues with keeping the throttle open because of all the torque management stuff.
Did you install all these parts and then take it to a tuner to tune? Sounds like you did?? I bet the tuner just didn't throw all he has at it and it left the shop with moderate timing and fueling and such. A tuner that didn't build the car isn't going to spend a whole lot of time tuning a car.
As others have said though. Don't chase a number. If the car feels good that's all that matters.
The tuner actually specialized only in GM vehicles, so that's all he does and he is reputable as far as I can tell... I did install all the parts alone and brought it to him for tuning.
I can't tell if the car left the shop with anything left on the table but when I did ask him my concerns and what I recall he mentioned that AFR was set somewhere around 12.5 or 12.8 (91 pump gas)... but don't quote me on that.
Then I remember he mentioned regarding Timing, he said he pulled 2 degrees from his max point since the gas here in California sucks, especially in the summer...
Regarding Torque management, I know asked him the next day to firm up the shifts since I love how the car would "Jolt" when it shifts... So he did it with his laptop and for a fact I know he firmed it up and then disable the Torque Management... But that was Transmission section type of tuning so I can't tell if anything regarding Engine calibration was done in that department (if applicable at all... since I would assume and believe that Torque management is a Transmission only type of calibration and wouldn't think it would influence WOT dyno results in the same gear... Correct me if I'm wrong?
Originally Posted by phantom1
You didn't mention if you have Headers. That could probably be why my TQ is slightly higher. Again though, try not to get caught up in the numbers. My C6 LS2 N/A Heads & cam, Ported Fast I/M with 4.10 gears Dynoed 512 rwhp, and only 436rwtq, but I manage to run 10.48 @134.08 mph in the 1/4 mile, and consistent 10.50s.
No Headers, just straight piped as my future plans for it is to turbo it so I don't want to spent the $ on headers that will go away later on...
Side note... As far as I know, Long Tube Headers can actually hurt TQ down low but will compensate for it with top end HP, no?
Last edited by BigMuscles91; 02-28-2019 at 06:29 PM.
Torque management is how this entire platform is tuned. Completely different than LS. Predicted torque, and then actual. If actual is higher than predicted, it could cause torque management to do certain things like close throttle body some, pull timing, etc. It is a torque based platform.
I see what you mean, however even you have higher TQ number then your HP and that what throws me off... Knowing that there is more Torque left out there that can be utilized will definitely yield more power to go along with it.
Since Torque creates Power and not the other way around...
That is too big of a throttle body and intake manifold for a stock LT1 without other supporting mods, especially headers. That is where your torque loss is. Essentially you are slowing down the intake velocity too much and the lack of headers just makes it worse. To be honest, I hope you have more mods planned. Even a full bolt on LT1 doesn't need a 103mm TB. That would be for a heads/cam car with a ported MSD.
When modifying your car you have to look at the end game goal, and mod based on this. Bigger is not always better in every scenario.
Last edited by Internets_Ninja; 03-01-2019 at 10:39 AM.
I’m sorry for my bump over here but I’ve been quite busy with things going on around...
With that being said, I managed to go to the track last weekend and the results are for you to judge below.
So how does it look? Am I where I should be with my Tourqe and Power?
The outside temperature was around 60’s and pretty humid as it was raining that week and actually sprinkling that day so we actually had to wait a little for the track to dry.
I didn’t warm up the tires at any run, and every launch was from ~1,500 on the RPM, literally basically almost from idle... Traction control was on and still the car was pulling power the entire 1st gear.
My last run was with TC off but got a flat 12 ET so...
That is too big of a throttle body and intake manifold for a stock LT1 without other supporting mods, especially headers. That is where your torque loss is. Essentially you are slowing down the intake velocity too much and the lack of headers just makes it worse. To be honest, I hope you have more mods planned. Even a full bolt on LT1 doesn't need a 103mm TB. That would be for a heads/cam car with a ported MSD.
When modifying your car you have to look at the end game goal, and mod based on this. Bigger is not always better in every scenario.
Is it really too big to that extend at the moment to hurt the Tourqe?
Yes, I do have plans to go Turbo, but we’ll see when I’ll be able to make it happen... That is why I did the Manifold, Thottle Body, E85 sensor and didn’t do long tube headers but just straight piped it for now :-)
Last edited by BigMuscles91; 03-13-2019 at 12:02 AM.
Torque management is how this entire platform is tuned. Completely different than LS. Predicted torque, and then actual. If actual is higher than predicted, it could cause torque management to do certain things like close throttle body some, pull timing, etc. It is a torque based platform.
OP, above is 100% true. I would consider finding someone with HP tuners to datalog some runs or even short hits, with the proper torque management layout logging all PIDs related to predicted, commanded, and actual torque among other things. There are several hard limiters in the ECU (and tcu if a8) that WILL partially close the throttle body as well as reduce timing to keep the engine on target with what it’s allowed to do with current calibrations. Being an “Ace” LSX tuner does not mean that your an ACE with our e92 ECU. If you have HP tuners, I can help you with the PIDs you need to log.
By doing this, and posting the logs here or on the tuning forum, you’ll find plenty of knowledgeable people willing to help, and in the process, learn. Win win
edit: I see that 60’ time, log pedal position and TPS, I’ll bet you stab it out the hole and only get 35% throttle until 1.7 sec later when it’s fully open. Going to need to tune the trans as well.
OP, above is 100% true. I would consider finding someone with HP tuners to datalog some runs or even short hits, with the proper torque management layout logging all PIDs related to predicted, commanded, and actual torque among other things. There are several hard limiters in the ECU (and tcu if a8) that WILL partially close the throttle body as well as reduce timing to keep the engine on target with what it’s allowed to do with current calibrations. Being an “Ace” LSX tuner does not mean that your an ACE with our e92 ECU. If you have HP tuners, I can help you with the PIDs you need to log.
By doing this, and posting the logs here or on the tuning forum, you’ll find plenty of knowledgeable people willing to help, and in the process, learn. Win win
edit: I see that 60’ time, log pedal position and TPS, I’ll bet you stab it out the hole and only get 35% throttle until 1.7 sec later when it’s fully open. Going to need to tune the trans as well.
Yes. But you don't spend much time in that area at the track except for launch so it doesn't hurt you that much. If you plan on boosting the car then you put the right mods on up front. But on the dyno, your low end torque will suffer but you will make more peak HP. Same mods on an LS7 don't have such a low torque effect down low since the additional cubic inches can actually use that much extra air.
Please understand that shaving .2 off the 60 foot will get you close to .5 in the 1/4 mile. It’s all about getting the mass in motion, and being at a progressively higher mph at every point along the way
1) The car made almost the SAME amount of Power as Torque on 91 Pump gas...?
All engines make more torque than horsepower until 5252 rpm. For the purposes of dyno graphs, in general, for several reasons, we do/will not care about any horsepower number (because it obscures our desire to compare cylinder pressure by including rpm)
In other words,
Torque is a useful curve, whereas power is merely torque obscured by the inclusion of a rotating (pie or 3.14xxxx) circular object with exactly 1 foot radius at some exact RPM (Instant).
in other, other words
Our goal is to increase engine performance safely, and to do this we are interested in effective cylinder pressure and the behavior of the process of combustion, which is given by the torque curve over a frequency range (revolutions/minute is a frequency, how many times per minute or second or millisecond etc...) which we will consider as "work" (torque is work). Power (the rate of doing work) on the other hand is independent of cylinder pressure, and when we seek performance gains what we are really looking for is safe improvements to effective cylinder pressure (torque) at any given frequency, but more specifically over the whole range of frequencies (area under the curve or the integral from 0rpm to maxrpm of a function of torque).
2) Then the switch to E85 gained 33 whp and ONLY 13 Torque??
E85 is incredible racing fuel, any gains are due to density improvements and it's resistance to detonation timing advantage.
The timing component advantage is only a severe advantage if timing was severely limited on the lower quality fuel to begin with. For example if you had a 12:1 compression engine and tried 93 but it would only go WOT with 7* btdc of timing without pinging and barely made 310hp. Then you tried E85 and were able to squeeze 24* of timing in and now it picks up close to 100hp. The E85 didn't "add 100 power", all it did was correct the fuel quality issue so the engine could run 'properly' (with enough timing advance and a slow enough combustion reaction rate to take full advantage of the compression ratio).
In other words, if an engine is severely fuel limited on 93 (or 87, etc...) then switching to better fuels like E85 'clears up' the fuel quality issue and allows the engine to 'make more power' even though its still doing the same thing it was doing before (it doesn't flow any extra air which is how power is usually increased, instead it just became a more efficient engine).
Likewise if you have a 9:1 compression engine on 93 octane, and it runs great at 24* of timing (modern LS variant), switching to E85 and trying to push even more timing (25, 26, 27, etc) isn't going to do much because there isn't very much power to be gained by slowing an already adequate combustion event down and simultaneously starting it sooner. All you are doing in that case is shifting the pressure curve around "looking" for minute changes (small differences) in output due to the current operating conditions (the combustion reaction will change speed if the engine's internal components become warmer so gains in one setting may be losses in another as the curve behavior changes with temperature). The E85 will help cool things off though so there is usually at least some kind of small benefit (if just that).
3) The tuner has a DynoCom, which he mentioned reads lower number compared to a DynoJet... More like a Mustang Dyno. With that being said, it seems that overall even if I add 5% to numbers to match DynoJet numbers... overall results (hp & tq) seems to be a little on the low side of things...
I will explain what we are interested in when reading dyno graphs and it isn't the exact numbers
4) What's that small dip around 5k rpm on pump gas 91?
lets analyze the dyno graph now [/QUOTE]
Torque starts off very high(compared to the peak) at 3k rpm which indicates a 'smallish' camshaft.
In other words, cylinder VE or cylinder effective pressure (torque) is dropping somewhat linearly to redline, which is acceptable if the engine really does have a 'small' or 'stock' cam.
~430ft*lbs of torque appears to be near max cylinder pressure for your elevation and ambient temperature. Note this number so when or if you take it to a dynojet you can make a comparison.
The dip, sometimes this is caused by a resonant frequency in the intake manifold (Helmholtz effect), sometimes it is caused by the activation of some kind of solenoid (VVT or VVL or V-whatever), sometimes it is a fluke in the tune (maybe it goes very rich there or timing drops out for a second, we have no air fuel curve or timing curve to examine so nobody will know). What does it mean? Its a soft spot in the torque output, a reduced cylinder pressure for some reason.
Now,
there is no air fuel curve. And no timing curve. So diagnostics is extremely limited. Also there isn o mention of smoothing being used, which further makes it difficult to get useful information from the curves.
If you take the car to a dynojet and use SMOOTHING:0, And get an air-fuel curve, then the diagnostics of torque curve becomes far more valuable.
02-28-2019, 12:11 AM
Dyno tune results seems off - Need 2nd opinion
If you bring that 60' down into the 1.7-1.9 you'll be mid to low 11s.
