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.
[Z06] The Blue Bullet Project: My Quest for a 600-hp Street-Drivable LS7
C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Hi Hib, I had my PSI 1511 springs replaced a couple months ago and had new Ti retainers installed, but have not taken an oil sample since. I would expect the new Ti retainers would wear just as the prior ones did and put Ti into the oil, but at fairly low concentrations of 5-8 PPM. As you may remember, I had the bottom end fully forged, partly because of Ti, but also because I was seeing some strange low oil pressure excursions. The engine seems to be working fine and I don't anticipate doing an early oil change or taking an early sample to see if there is Ti in it. I have not gotten any spring pressure tests back on my old (22K mile) PSI springs. I was hoping to have those to compare with your results.
This Fall I'm going to have to do some testing. I'll remove some parts which don't have EOs, for example: I'll reinstall the stock throttle body and the stock air filter assembly. Then I'll flash the ECM with my stock calibration then road test. If the engine meets the idle stability necessary and will set the I/M monitors, I'll go test.
Hi Hib, I have had my oil checked every 2K miles. After the head work the TI went from 0 to just registering, new retainers, and the following 2K miles was gone again and every 2K since then. I think this is an indication that this milage is okay for seeing changes.
Good Luck with your TI issue! 🤞🏻
I have not worked on that project, yet. My registration renews in May so I have some time.
The obvious questions are: once I have the stock cal reinstalled....
1) Will the engine run well enough at the stock idle (about 600 rpm as I recall) to not misfire excessively?
2) Will it run well enough in closed loop to set all the OBD2 readiness monitors?
Last edited by Hib Halverson; 02-18-2022 at 10:35 AM.
I have not worked on that project, yet. My registration renews in May so I have some time.
The obvious questions are: once I have the stock cal reinstalled....
1) Will the engine run well enough at the stock idle (about 600 rpm as I recall) to not misfire excessively?
2) Will it run well enough in closed loop to set all the OBD2 readiness monitors?
Might b worth some experimenting around the CVN(?) values.
Does turning emission monitors off change that number?
Don't think there's any bandaid for the idle speed.
Good luck.
Been through enough BS with that car already!
Hi Hib, I had my PSI 1511 springs replaced a couple months ago and had new Ti retainers installed, but have not taken an oil sample since. I would expect the new Ti retainers would wear just as the prior ones did and put Ti into the oil, but at fairly low concentrations of 5-8 PPM.
How did you decide that 5-8PPM was "fairly low"?
As you may remember, I had the bottom end fully forged, partly because of Ti, but also because I was seeing some strange low oil pressure excursions. The engine seems to be working fine and I don't anticipate doing an early oil change or taking an early sample to see if there is Ti in it.
I know you went to forged pistons and forged steel conn rods. What brand and CR of pistons? What brand of conn rods? What was done to rebalance the rotating assembly for the additonal mass of the steel rods?
I have not gotten any spring pressure tests back on my old (22K mile) PSI springs. I was hoping to have those to compare with your results.
I'm on a road trip right now in Southern Nevada and away from the info at my shop. I tested all the old springs then called PSI and gave them the pressures I tested. They said the springs were "borderline", so I bought new ones. When I get back, I'll see if I still have the spring test data.
Originally Posted by Pacha's Z06 RF
Hi Hib, I have had my oil checked every 2K miles. After the head work the TI went from 0 to just registering, new retainers, and the following 2K miles was gone again and every 2K since then. I think this is an indication that this milage is okay for seeing changes.
Good Luck with your TI issue! 🤞🏻
'Preciate your comments, "Pacha's ZO6"
Originally Posted by grpweld
It will show & give a good indication but you will need to figure a your % comparatively. (4k 1st sample vs. 2K 2nd. sample=50%) so just do the math
How did you decide that 5-8PPM was "fairly low"? I know you went to forged pistons and forged steel conn rods. What brand and CR of pistons? What brand of conn rods? What was done to rebalance the rotating assembly for the additonal mass of the steel rods? I'm on a road trip right now in Southern Nevada and away from the info at my shop. I tested all the old springs then called PSI and gave them the pressures I tested. They said the springs were "borderline", so I bought new ones. When I get back, I'll see if I still have the spring test data.
t!
5-8PPM, just a guess, none of the bearings were in real tough shape and the scuffing on the Ti rods was not bad, but I was seeing some low oil pressure excursions at idle including the day I drove the car down to CPR, so I am happy I had all the work done.
Diamond LS shelf forged pistons, ~ stock CR so with the .030 shaved heads about the same as before 11.7:1, dyno'd and tuned for 91 octane gas as befor. Callies Compstar 4340 H-beam con rods, Compstar forged crankshaft. I don't know all the balancing they did as WFO did the whole bottom end, but the crank and pistons are lighter than stock, dyno after the work was virtually the same as before, which is what I expected.
I saw your spring test post earlier and, while I had that in mind, your results confirmed I should had the springs/retainers/seals replaced as I run the engine harder than you do and CPR agreed 20-25K miles is about the max you would want to run the springs with the .660 lift of the K501 cam. I asked to have CPR test the old springs but do not have any results if they have been tested.
5-8PPM, just a guess, none of the bearings were in real tough shape and the scuffing on the Ti rods was not bad, but I was seeing some low oil pressure excursions at idle including the day I drove the car down to CPR, so I am happy I had all the work done.
Do you remember how many miles were on the Ti rods at the time you removed them?
Diamond LS shelf forged pistons, ~ stock CR so with the .030 shaved heads about the same as before 11.7:1, dyno'd and tuned for 91 octane gas as befor.
I might have asked you this before, but if you're using 91-oct gas, why did you mill the heads? Wouldn't it have been better to take less CR and more spark?
Callies Compstar 4340 H-beam con rods, Compstar forged crankshaft. I don't know all the balancing they did as WFO did the whole bottom end, but the crank and pistons are lighter than stock, dyno after the work was virtually the same as before, which is what I expected.
Ok, so your rotating assembly has less mass than before, but what do the rod/piston assemblies weigh now and what did they weigh before? A forged steel conn rod usually weighs more than a Ti rod. To have the rotating assembly weigh less than stock means mass had to come out somewhere. I'll add that my belief has been that, since GM admitted that the Ti rods were in LS7s to reduce the effect of the piston/rod assembly's mass' on oil film strength at BDC and TDC, going to a heavier steel rod is ok as long as you, also, go to a better oil–say...Red Line 0W40 rather than Mobil 1 5W30–and that the effect of slightly higher rod piston mass doesn't slow the engine's ability to acceleate that much.
I saw your spring test post earlier and, while I had that in mind, your results confirmed I should had the springs/retainers/seals replaced as I run the engine harder than you do and CPR agreed 20-25K miles is about the max you would want to run the springs with the .660 lift of the K501 cam.
Considering your cam is far more aggressive than what I run, I'd have replaced the springs and etc, at 25K-mi, too.
I asked to have CPR test the old springs but do not have any results if they have been tested.
Bummer. It would have been interesting to have those numbers so we could call PSI and ask their opinion.
As far as the Ti content in my oil–I took the car on a 2024 Caravan prerun trip i to Nevada. Was over to Henderson then out to Pahrump and finally back to Goleta. I now have about 1800 miles since the last Blackstone test. This Sunday I'm going to put another 150-200 miles on the car on a Corvette Club trip and then I'll sample the oil. If the Ti content goes down, I'll rule-out the rods.
X'ing my fingers.
Last edited by Hib Halverson; 02-22-2022 at 02:35 PM.
Do you remember how many miles were on the Ti rods at the time you removed them? 57,000 miles, about 24 track days and a good number of extended high speed runs and trap speed events.
I might have asked you this before, but if you're using 91-oct gas, why did you mill the heads? Realistically had the heads milled so if I sold it to an area with 93 octane, just a tune to pick up a little more power.
Wouldn't it have been better to take less CR and more spark?Ok, so your rotating assembly has less mass than before, but what do the rod/piston assemblies weigh now and what did they weigh before? A forged steel conn rod usually weighs more than a Ti rod. To have the rotating assembly weigh less than stock means mass had to come out somewhere. I'll add that my belief has been that, since GM admitted that the Ti rods were in LS7s to reduce the effect of the piston/rod assembly's mass' on oil film strength at BDC and TDC, going to a heavier steel rod is ok as long as you, also, go to a better oil–say...Red Line 0W40 rather than Mobil 1 5W30–and that the effect of slightly higher rod piston mass doesn't slow the engine's ability to accelerate that much. I haven't used M1 5W-30 since my first track day ( at ~ 13K miles) and 260*+ oil temps. I usually run M1 0W-40 Euro formula or Amsoil 5W-30 when it comes back from CPR. Just about the same power before/after the bottom end work and still 160 MPH trap speeds in the 1/2 mile and just at fast at 7500'DA up in Ely NV in the 1-mile trap.
Considering your cam is far more aggressive than what I run, I'd have replaced the springs and etc, at 25K-mi, too.Bummer. It would have been interesting to have those numbers so we could call PSI and ask their opinion. Springs replaced at 22K miles based on your test results, thanks. CPR normally would want the springs replaced in their modded engines that are really used at between 20-25K miles and I had no problem doing them at that time given my use..
As far as the Ti content in my oil–I took the car on a 2024 Caravan prerun trip i to Nevada. Was over to Henderson then out to Pahrump and finally back to Goleta. I now have about 1800 miles since the last Blackstone test. This Sunday I'm going to put another 150-200 miles on the car on a Corvette Club trip and then I'll sample the oil. If the Ti content goes down, I'll rule-out the rods.
Hib, attached are the before/after dyno runs from the HCI run in April 2018 and the forged bottom end in September 2018, same dyno, very close on power and torque. The April tune looks like it was just a little more aggressive, but the car drives and traps just about the same.
Last edited by AzDave47; 02-26-2022 at 10:55 AM.
Reason: HP-TQ on same vy-scale
Clearly, your April fuel calibration was just a bit on the lean side, especially below 4500RPM. That makes a little more torque, but it also puts more combustion heat into the chambers. For the type of duty your engine sees–1/2-mile runs at WOT and so forth–you were smart to give up a very small amount of torque with half a ratio less AFR in exchange for a little less combustion heat, less tendency to detonate and better reliability/durability.
Since you posted the results as an image file, I downloaded it. I opened it with my image software, so I could use the app's "guides" to measure the differences. In the midrange, you've given up about 12-lbs/ft by adding some fuel. At peak torque, you were down about 10-lbs/ft. By 5500 there was almost no difference in torque.
Looking at the AFR data, the significant differences are below 4500-RPM. If your tuner wants to get into "splitting hairs", you could have him/her lean slightly below 4500, but not as much as it was leaned in April, but leave the fuel schedule above 4500 alone.
Two questions: t
1) Was anyone taking engine controls data during the test. If so, was there any knock retard?
2) There is just a slight difference in the correction factors–1.04 vs 1.03. It's been a really long time since I've run on a Dynojet so my lack of current knowledge of Dynojet's Winpep software has me not understanding why the slight difference exists. Can you shed any light on that?
3) So I clearly understand your use of the term "forged bottom end"...previously, your rotating assembly was stock, ie: cast-aluminum pistons, forged titanium rods and a forged steel LS7 crank. Your rotating assembly now, is Diamond forged-aluminum pistons, Calles forged steel rods and a Calles forged steel crank shaft. Have I got that right?
Last edited by Hib Halverson; 02-26-2022 at 11:54 AM.
Hib, attached are the before/after dyno runs from the HCI run in April 2018 and the forged bottom end in September 2018, same dyno, very close on power and torque. The April tune looks like it was just a little more aggressive, but the car drives and traps just about the same.
Question for you on this - did the tuner request a flat enrichment table and it came out wavy like that? Or did the tuner make their cal wavy purposely?
Hib, you got my builds right. As far as adjusting down below, When I do straight line event I'd I'd only be below about 4800 RPM on the start in first gear, thereafter the shifts drop me back into the 4800-5100 rpm range. On a road course I suppose it could be enriched below 4500, but I don't spend too much time there. NicD (the tuner throughout my build adventures with CPR) knows I run 91 on the street and the engine is tuned for that. When I do events I do try to get some 100 octane to boost tank octane to 93-94 to minimize the likelihood of detonation. The pistons that came out after 57K miles did not show evidence of knock.
On the 1.04 vs 1.03 adjustment to SAE, on the April run it was 74*, 28.5 in-hg and 33.4% humidity; on the October run it was 74*, 28.76 in-hg and 52% humidity. It is quite possible that the one correction factor was 1.0345 rounded down to 1.03 and the first was 1.038 rounded up to 1.04, so perhaps not a full 1% difference.
Apocolipse and Hib, the tuner is one of the best LS tuners (and generally) in AZ. I know virtually nothing other than you don't want the Air/fuel ratio too lean. I tell him the type of performance events I do, the elevation (800' to 6500' for different events) and he does the tune that should work for me on the street and at events. I do know that cam'd LS7s do have that wavy torque curve, particularly in the 2000-5000 range. I had Pfadt 1 7/8' Tri-Y headers several years ago before I went to 2" ARH, now with OR X-pipe. The ARH had one big wavy torque in the 2000-3000 rpm range that the Pfadt's did not have, but the ARH were more than 50 lb-ft of torque stronger down low than the Pfadts.
Hib, you got my builds right. As far as adjusting down below, When I do straight line event I'd I'd only be below about 4800 RPM on the start in first gear, thereafter the shifts drop me back into the 4800-5100 rpm range. On a road course I suppose it could be enriched below 4500, but I don't spend too much time there. NicD (the tuner throughout my build adventures with CPR) knows I run 91 on the street and the engine is tuned for that. When I do events I do try to get some 100 octane to boost tank octane to 93-94 to minimize the likelihood of detonation. The pistons that came out after 57K miles did not show evidence of knock.
Detonation has to be significant for pistons to show signs of it. Also, looking at pistons after 57K may not tell you the whole story because, unless the detonation occurred shortly before you tore down the motor, evidence of previous detonation that was short of softening the aluminum, might have disappeared. Your best bet is to be recording knock retard data when running on the dyno or running an event. Even a cheap, consumer-grade scan tester can save data. Second best is to look at plugs. In my experience, it takes about 95-96-oct for me to stay out of detonation if I am running E10 gas (usually runs about 7.5% ethanol) and shooting for .86-.85-lambda. That said, there are differences in our engines and duty cycles: 1) dynamic cylinder pressure. My cam is milder than is yours, so it's going to make more cylinder pressure, increasing the engine's tendency to detonate, particularly around peak torque. 2) DA. Most of my octane testing has been at sea level on cool to warm days. You're typically operating at somewhat to much higher altitudes, so, even though your CR is higher, your need for octane is likely less .
On the 1.04 vs 1.03 adjustment to SAE, on the April run it was 74*, 28.5 in-hg and 33.4% humidity; on the October run it was 74*, 28.76 in-hg and 52% humidity. It is quite possible that the one correction factor was 1.0345 rounded down to 1.03 and the first was 1.038 rounded up to 1.04, so perhaps not a full 1% difference.
Copy that.
Apocolipse and Hib, the tuner is one of the best LS tuners (and generally) in AZ. I know virtually nothing, other than you don't want the Air/fuel ratio too lean. I tell him the type of performance events I do, the elevation (800' to 6500' for different events) and he does the tune that should work for me on the street and at events.
Does NicD come to the chassis dyno venue and does the cal work there? Also, if he's at the dyno, does he take engine controls data? I ask because, since you run 91 a lot of the time, I'll interested to look at your spark and KR data from when you are doing dyno pulls on 91-oct fuel.
I do know that cam'd LS7s do have that wavy torque curve, particularly in the 2000-5000 range. I had Pfadt 1 7/8' Tri-Y headers several years ago before I went to 2" ARH, now with OR X-pipe. The ARH had one big wavy torque in the 2000-3000 rpm range that the Pfadt's did not have, but the ARH were more than 50 lb-ft of torque stronger down low than the Pfadts.
"Wavy" they are, indeed. Mine is "wavy" from 3500-4800.
Finally, I was just looking at chassis dyno data from my car, and you're about 50-hp up on me because of your cam and your headers. I'm making about 545 SAE at the tire at 6200 and you're making 592 SAE at 6600.
NicD is there in the driver's seat with his laptop hooked up on every dyno run (probably 24-30 over 3-4 years). It is likely he has/took/saw that data, but I do not have it. I did get the Dynojet files of all the runs on thumb drives and have them on my computer, but don't know if those contains any info you are asking about. If you think it does, I can send you a couple files to your normal email address (I think I have it) for you to look at Hib.
The DynoJet run files won't help me. What I'd like to see is the engine controls data NicD logged during the runs, but it could be that he's not willing to share that stuff.
02-16-2022, 09:18 PM
