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Organized Drag Racing and AutocrossDrag racing and autocross discussions and questions. Techniques, tips, suggestions, and "what will I run?" questions.
I'll start this off by saying I am going to make this post as detailed as possible.
I have a 87 TA that has essentially a cammed LS2 with a 3400 stall converter that is only running 12.66 and trapping 108mph in the quarter(with passenger). This was on the street with a Dragy cutting a 1.98sec 60 foot(with a passenger). At the drag strip it ran 12.9 @105 while cutting a 1.7 60 foot on a very hot day(150* intake temps) with the previous fuel setup.
With those times and the cars weight, Wallace racing calculators put me at 355hp. An LS2 has 400hp factory and this engine should be somewhere around 470-490 crank hp based on other similar setups, so something is certainly wrong.
Are these calculators complete BS? Or is this a normal time and trap speed?
Mods that matter:
3450 pounds with driver
iron 6.0ls 799 heads
216/220 .560 114LSA cam
TBSS intake with 92mm tb
speed engineering longtube headers to 3 inch single straight pipe out the back
9 bolt 3.27 gears
275/40r17 mickey et street ss
Flex fuel system with 525lph in tank pump
50lb hr flex fuel truck injectors (cleaned and flow matched)
Holley Terminator x max street tuned by me
3400 stall 4l60e, converter is a Boss hog street bandit something rather 9.5inch diameter.
I am having difficulty uploading my datalog so its currently in a google drive folder, I am unsure if this will work. I can also PM those who are willing to look at it. Datalog
I am suspecting the stall converter to be my issue as it seems to be too loosey-goosey. This is my first stalled go-fast car though.
What gives? For those that offer insight, thank you in advance.
Regarding your calculator question.
Keep in mind that your quoted HP numbers for your LS are peak HP. The calculators can only estimate the power to the wheels over the entire run. So it's an average rather than peak.
If you were to possibly equip your car so that RPMs where in a 1000-1500 RPM window, then your ETs and MPH will improve without any changes to the engine.
Also, improving the 60' will have an effect on the top end. It's said, at this level of racing, that a tenth in the 60 is worth two tenths at the top.
For the record, based on your results when compared to my own (12.4x@108) ,I'm suffering from the same malady as you. If I were to step up from the TCI off the shelf 10" converter and got a properly spec'd Yank converter (for example), I'd find, as I have in other cars, that the ET and MPH will improve as the shift recovery is much better and the engine stays in a tighter RPM range for the entire run.
Also too, consider the weather on race day. A poor density altitude will kill your results. For reference, try the Drag Times DA calculator and reconcile your results to seal level.
I always thought the calcs were flywheel rated. They always worked fairly decent for me based on flywheel.
i will say those numbers do seem way off what id expect this combo to run. That cam is small for a ls2 but should make real decent power, like closer to 380-400 whp.
I always thought the calcs were flywheel rated. They always worked fairly decent for me based on flywheel.
i will say those numbers do seem way off what id expect this combo to run. That cam is small for a ls2 but should make real decent power, like closer to 380-400 whp.
at 3450 lbs that should be in the 11’s at 115-117
Some of the Wallace calculators will provide both flywheel and rear wheel data. Some kind of magical math wizardry that you have to accept with some skepticism.
But it's an average just the same.
My shift drop with the converter is about 1400 rpm meaning the lowest rpm I see during a run is about 5000. Would locking my converter at WOT be worth a shot or would that be a bad idea in regards to the life of the converter clutch?
My shift drop with the converter is about 1400 rpm meaning the lowest rpm I see during a run is about 5000. Would locking my converter at WOT be worth a shot or would that be a bad idea in regards to the life of the converter clutch?
Have you data logged that result or is it observed on the tach?
Whose converter do you have and do have a PN?
Typically, or at least from understanding, lockup and WOT isn't a good idea unless the converter is designed to handle the torque.
I believe the datalog is linked in the OP. The rpm drop is observed on the datalog and the tach.
The converter is a Boss hog Street bandit 3200-3600 9.5" converter.
Boss hog PN 49454
Summit racing PN APE-49454
I after a single 1/4 mile hit on a 80* day, trans temps can rise more than 10*
For those without holley software, here are some pictures of a quick hit on the highway onramp last night. Different parameters selected in each to be easier on the eyes.
Just used the wallace racing calculator for converter slip and I am coming up with 22%.... ouch!
I might try a single pull with the TCC locked at WOT to see if I pick up a few mph to confirm if the converter is my issue...
Just used the wallace racing calculator for converter slip and I am coming up with 22%.... ouch!
I might try a single pull with the TCC locked at WOT to see if I pick up a few mph to confirm if the converter is my issue...
Yikes. From what I've seen, that's a big number for slip.
You're shift RPM drop is impressive (at least from my perspective) but maybe that slip, with that converter, is what you're giving up.
Good luck with the lockup.
Somewhere someplace, I believe Orr has some experience experimenting with the lockup. Might be chassis dyno but still something to draw on.
Orr...?
For those without holley software, here are some pictures of a quick hit on the highway onramp last night. Different parameters selected in each to be easier on the eyes.
Am I seeing shift at about 6500 and recovery just below 5000?
Is there wheelspin accounted for in there being a street surface and all.
I found the track combined with slicks really pulls the shift RPMs down hard. If I pin it on the street, I can be at 6500 RPM flat right into third gear. And that's not WOT either otherwise I'd be swapping ends. Hard on the tires too!
I think you're on to something with converter slip though. It would certainly kill the trap speed.
What rear gear in it? Weird to me its dropping that much on shift but still 22% slip. Sometimes more gear can help reduce that but sounds like its not tight enough
i have played with lock up. It may help you alot more than me as i never had a converter that slipped as much as that one, but i saw a half mph to 1 mph gain locking mine. Its been 10-15 whp on mild setups on the dyno. my L98 and 383 both didnt seem to do any better with it locked. ET slowed and mph only increased a hair on some occasions. It was sensitive to when you locked it.
Base fuel map In 3D! ethanol base fuel offset timing table
Unless I am missing something huge in the tune, I believe I'm just not putting the power to the ground.
There's a lot to say, I think it's best that you get a professional tune. I think it's going to be worth paying for.
The volcano at high rpm in your fuel map indicates you have a fuel supply problem, probably holding back your engine. Volcanoes are formed by the self-tuning feature when the injector duty cycle starts to go up trying to compensate for low fuel pressure.
Thank you for the input.
I understand what you are saying about the learn feature adding fuel, but I that will only happen if you hit "apply to base" while in the learn table. I have not done that.
Learn is currently off and has been for a while, it always says I need to add fuel but my AFR seems to be ok.
I intentionally put the little hump in the graph near/around peak torque because that is what made sense in my head. That my not be right, I have alot to learn.
I have not changed the tune much since replacing my inline 255 fuel pump(not enough output) with the aforementioned in-tank 525. With the inline fuel pump it made the 12.9 second run.
I think I will start playing with lockup first and then adjust base fuel to make one change at a time.
No, not if you are referring to gas scale on wideband sensors.
stoich changes but lambda does not, which lambda of 1 is always stoich, or 14.7 for air fuel for regular gasoline. Its like 9.6-9.7 i think for e85.
So yeah more ethanol you have stoich gets richer but widebands only look at lambda and convert. Leave the holley software in gas mode. So idle and light cruise target lambda is typically .95-1.05. Or afr 14-15.4.
max power is typically lambda .83-.89 or 12.2-13.0. High ethanol over 51% can usually run richer and not lose power so can be slighty richer than gas but yours is way rich for a na car
Holley I think will show lambda if you want. If you already know gas scale very well then you kinda dont need to worry about it. The engine is going to tell you what it wants. The number doesnt really matter too much. Leave it on the richer side of max power and best manners usually works well in the long run. Mpg tuning likely is gonna be leaner than stoich, and require messing around
I pulled some fuel out of the base map and adjusted my Target AFR. I will add those pictures below.
Ill be going out again tonight using the dragy to log 1/4mile times, I will update soon. I will be only adjusting fuel and leave the lockup stuff for later.
Here is an attempt to upload my tune using google drive because TGO says the .terx files are not accepted.
I essentially just pulled 5 points of fuel from the higher MAP ranges in the base map, leaned target AFRs, and pulled 1% from ethanol offset table. I hope this makes a change!
Regarding timing, I think that 25 degrees is enough for an LS2, no need to push it. On higher ethanol content I have a table that adds like 2 degrees of timing.
The target afr change table you are referring to is to offset my target afr based on my ethanol content. So the computer will target richer afrs when ethanol content is higher.
Holley has a video on how to use a flex fuel sensor and I basically just followed the steps on that to the T.
Thank you all for the input, I will be updating with those datalogs and dragy 1/4 mile times soon!
Oh ok. Yeah i would delete that table. The afr doesnt need to change with ethanol content, just the amount of fuel changes, being that more ethanol is needed. Hence the ethanol fuel flow multiplier. The closed loop function will correct to target air fuel. Just leave it allowing like 10-15% corrections and tune your fuel flow multiplier for known ethanol content fuels
Good news.
With ONLY the fuel changes, I picked up 2mph even in 25 degree warmer weather. The car feels more responsive.
12.62 @110mph
Now to after the pull. I noticed that with new fueling map the engine likes to idle with about 28* timing, 6 more than before. Keep in mind my reluctor wheel was welded on by the shop that built my shortblock, so it wouldnt surprise me if it was a degree to two off. With that in mind I added 2 degrees up top in my base timing table, now around the 27 number that Orr had mentioned before. I will do another pull tonight once it is a little cooler and hopefully I can pick up a few more mph.
I also recalculated my converter slip with the new info from the datalog, it is now at 16%
I also noticed that I am not at 100% throttle until about 35mph in the most recent pull, but my MAP reading are still 90+, so I think that wont make too much of a difference. Just need to be heavier with my foot.
I have since changed transmissions, (now built 4l80e, the 60e let go) and haven't done any draggy or dragstrip runs. I hope to change that in the next few weeks though.
I think the converter killed the trans.
Ill report back with data.
I don't have any draggy data to back this up, but with the new trans setup, I seem to be going much faster. That converter on the 60e was junk. Not putting any power down.
I have since added a turbo as well, 7psi and and I am slowly turning it up. The car is responding very well and is very fast. I have also learned so so much in regards to tuning, fixed a bunch of self inflicted problems by trail and error with lots of hours behind the keyboard. Lesson of this thread - Don't get a cheap converter! and there is always more to learn
10-05-2022, 09:20 PM
