BUILD THREAD 86 GP 2+2~Blown 6.0

81cutlass

Comic Book Super Hero
Thread starter
Feb 16, 2009
3,279
113
Western MN
Fiddled with some tune stuff and took the car for a spin.

I THINK the spark smoothing that I turned off fixed my choppy idle when I am coasting in neutral. It seems better. My mid throttle low load high RPM limp mode issue also seems solved. The cruise not working is still an issue I need to work on.

In other news my aftercooler water temp circuit temp sensors work great! At at least with short bursts the heat exchanger is doing a good job. Post blower IAT crawls up to 115F on short pulls and the water temp going out of the aftercooler tops out at 78F while the post heat exchanger is rock solid at 62F. It was 60F outside tonight so that tells me the heat exchanger is pulling all of the ~20F of temp rise out of the water and the aftercooler in the intake is just not 100% keeping up, which is the only thing in the system I can't really do anything with.

Seeing fuel pressure is also nice. It doesn't move around as much as I thought. Maybe the regulator is sticky? I intended to target 4 BAR (60psi) but it sits at 70psi at idle, which is honestly like 20PSI high. It should be 60psi at atmospheric pressure, 50PSI at idle like 15 inches of vacuum, and 70psi at 10psi of boost. I do get 1:1 rise under boost, 10PSI of boost results in 80PSI of fuel pressure at first, but through 3rd gear it starts to drop. Possibly a wally 450 is running out of flow at 80psi with my flow requirements? You can see the plot on the green line in the 4th column my FP (psi) is 81 at the start of 3rd gear and trails down to 70psi at the end.

I did find out my stewart warner pressure gauge I set the fuel pressure with initially 4 years ago is off. I trust this sensor more than that old stewart warner gauge. I might toss my mechanical gauge on too to double check.

I'm not sure if I should fix my fuel pressure or leave it as is. The fuel map is kinda set for 70 psi base now, and changing it to 60 is going to screw it all up, but the fuel table is far from expertly calibrated by any means.

Oh and my timing is way conservative. 12 degrees on 10psi on E65 is laughable. It would probably be safe with 89 octane. Holdener ran 23 degrees on e85, 12 PSI on an M122 4.8 he tested a few months ago and the local tuning guy I want to hire said he would put 8+ in it without a second thought.

And it still annihilates the tires in 1st and 2nd gear without trying.
1619753381303.png

70
 

motorheadmike

Geezer
Nov 18, 2009
7,083
113
Ottawa, Ontario Canada
Fiddled with some tune stuff and took the car for a spin.

I THINK the spark smoothing that I turned off fixed my choppy idle when I am coasting in neutral. It seems better. My mid throttle low load high RPM limp mode issue also seems solved. The cruise not working is still an issue I need to work on.

In other news my aftercooler water temp circuit temp sensors work great! At at least with short bursts the heat exchanger is doing a good job. Post blower IAT crawls up to 115F on short pulls and the water temp going out of the aftercooler tops out at 78F while the post heat exchanger is rock solid at 62F. It was 60F outside tonight so that tells me the heat exchanger is pulling all of the ~20F of temp rise out of the water and the aftercooler in the intake is just not 100% keeping up, which is the only thing in the system I can't really do anything with.

Seeing fuel pressure is also nice. It doesn't move around as much as I thought. Maybe the regulator is sticky? I intended to target 4 BAR (60psi) but it sits at 70psi at idle, which is honestly like 20PSI high. It should be 60psi at atmospheric pressure, 50PSI at idle like 15 inches of vacuum, and 70psi at 10psi of boost. I do get 1:1 rise under boost, 10PSI of boost results in 80PSI of fuel pressure at first, but through 3rd gear it starts to drop. Possibly a wally 450 is running out of flow at 80psi with my flow requirements? You can see the plot on the green line in the 4th column my FP (psi) is 81 at the start of 3rd gear and trails down to 70psi at the end.

I did find out my stewart warner pressure gauge I set the fuel pressure with initially 4 years ago is off. I trust this sensor more than that old stewart warner gauge. I might toss my mechanical gauge on too to double check.

I'm not sure if I should fix my fuel pressure or leave it as is. The fuel map is kinda set for 70 psi base now, and changing it to 60 is going to screw it all up, but the fuel table is far from expertly calibrated by any means.

Oh and my timing is way conservative. 12 degrees on 10psi on E65 is laughable. It would probably be safe with 89 octane. Holdener ran 23 degrees on e85, 12 PSI on an M122 4.8 he tested a few months ago and the local tuning guy I want to hire said he would put 8+ in it without a second thought.

And it still annihilates the tires in 1st and 2nd gear without trying.
View attachment 174268
70

Drop it down to the 58psi it's supposed to be. Less base pressure gives you more headroom for power or error. You are losing about 20 percent of that window between your pump and injectors.

I prefer to use IDC/PW to add fuel over mechanical pressure. I remember tuning with an AFPR and a NB02 with my Buick and it was a stupid concept then, as it is now.

You have the means... fix the tune.
 

81cutlass

Comic Book Super Hero
Thread starter
Feb 16, 2009
3,279
113
Western MN
Drop it down to the 58psi it's supposed to be. Less base pressure gives you more headroom for power or error. You are losing about 20 percent of that window between your pump and injectors.

I prefer to use IDC/PW to add fuel over mechanical pressure. I remember tuning with an AFPR and a NB02 with my Buick and it was a stupid concept then, as it is now.

You have the means... fix the tune.

I know you are right, I just don't wanna lol.

I'll fix it....
 

motorheadmike

Geezer
Nov 18, 2009
7,083
113
Ottawa, Ontario Canada

Supercharged111

Royal Smart Person
Oct 25, 2019
2,170
113
Colorado Springs, CO
Drop it down to the 58psi it's supposed to be. Less base pressure gives you more headroom for power or error. You are losing about 20 percent of that window between your pump and injectors.

I prefer to use IDC/PW to add fuel over mechanical pressure. I remember tuning with an AFPR and a NB02 with my Buick and it was a stupid concept then, as it is now.

You have the means... fix the tune.

I remember tuning a friend's R32 Skyline with big turbo, an Apexi Super AFC, and an AFPR to try and make it happy. Thing pulled pretty damn hard, but 81 has a bit more at his disposal than we did that day.
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
2,928
113
Upstate NY
Oh and my timing is way conservative. 12 degrees on 10psi on E65 is laughable. It would probably be safe with 89 octane. Holdener ran 23 degrees on e85, 12 PSI on an M122 4.8 he tested a few months ago and the local tuning guy I want to hire said he would put 8+ in it without a second thought.

And it still annihilates the tires in 1st and 2nd gear without trying.
Regardless of what anyone else tells you, be careful of the timing. I do agree that you could use more, M122 on a 4.8 and an LSA on your 6.0 are not the same build. Rod to stroke ratio and stroke to bore ratio are BS topics most of time EXCEPT in timing. The burn rate at the same boost level with a different blower will not be the same, and the amount of timing lead with both a bogger bore and different piston speed will not be the same.

So if you were to add another 8 degrees of timing and pickup 50-100whp, what will be accomplished? Sounds like it's silly fast already if you can destroy tires at will. I can't remember what your RPM range in the last 1/8 mile of the track, but I'll guess it's alot larger than someone with an auto - probably double. That's where the tricky part of the tune is with a stick car.

Personally, I'd hold onto those extra degrees to use once you can get it off with the line. My two cents - take'm or leave them.
 

81cutlass

Comic Book Super Hero
Thread starter
Feb 16, 2009
3,279
113
Western MN
I checked my logs and I am only at 70% injector duty cycle on E70 with 80lb injectors at probably 70 PSI, so I am good. I am going to turn my base pressure down.

My injectors have more headroom than the pump so I'll just add injector pulse time and reduce pressure.

Mike is right.

Regardless of what anyone else tells you, be careful of the timing. I do agree that you could use more, M122 on a 4.8 and an LSA on your 6.0 are not the same build. Rod to stroke ratio and stroke to bore ratio are BS topics most of time EXCEPT in timing. The burn rate at the same boost level with a different blower will not be the same, and the amount of timing lead with both a bogger bore and different piston speed will not be the same.

So if you were to add another 8 degrees of timing and pickup 50-100whp, what will be accomplished? Sounds like it's silly fast already if you can destroy tires at will. I can't remember what your RPM range in the last 1/8 mile of the track, but I'll guess it's alot larger than someone with an auto - probably double. That's where the tricky part of the tune is with a stick car.

Personally, I'd hold onto those extra degrees to use once you can get it off with the line. My two cents - take'm or leave them.

I hear you on that. I agree there is some timing overhead left, but would prefer to test results either at the track or on a dyno and not just toss in timing blindly. I forgot rod ratios and bore diameter matters on timing. Last I messed with timing at the track for an apples to apples comparison it I was on 91 and less boost. I had 14 degrees in it and went to 16 and it slowed down, but honestly its been 2-3 years and I forgot what parameters I used.

Gaining 50-100hp especially down low wouldn't help. I had planned to start feeding timing in last fall on drag weekend, but blowing the rear up but the stop to that. I have about 2 more PSI to put in also with a smaller pulley. Now that I have a good handle on my IAT's, I am going to put more boost in and see if it stays cool. If it does, then I will start adding timing until it slows down.

I've always wanted to get it to hook before I put more power in, and just never have had success launching.

I see 4100 rpm on the low side in 3rd and 4th gear and run through the traps at 5500 rpm in 4th. I shift into 4th just after the 1/8 mile so its in 4th gear essentially the entire last 1/8 mile.

Looking at my tune I also only have 5-8 degrees of timing in 30-50% TPS 0-3 psi condition and it's falling on its face. I have reached out to the well respected local LS tuner (the one that recommended adding timing last drag weekend) about hiring him to tune my car, and got zero response. I might reach out to the other tuning guy in the area with a dyno and buy some time on his dyno where I dial in the mid boost, mid rpm condition timing and fuel.

I think a good plan for the summer is
1. Get the car to hook with the power it has
-I have already fixed a few things. Took a lot of slop out of the upper control arms (wheel hop?), fixed my instant center (wheel hop?), ordered adjustable rear shocks (wheel hop), working on the clutch clamp delay valve. Possibly add timing in the WOT, mid boost, mid RPM range, the tuner said low timing there will make it feel like the car is bogging and out of the power range when really it just needs more timing, if it makes too much power there I just need to turn the 2 step RPM down or slow the clutch delay valve down when I get that working.
2. Add boost and keep boost if the IAT's stay under control
3. See if the car still hooks
4. Feed in timing


Thanks for the helpful comments guys. It's good to hear others viewpoints and make better decisions from it. I think a LOT of problems I see are people getting stuck in their own heads and doing the same (dumb) things when really doing something that takes some time will help solve the issue.
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
2,928
113
Upstate NY
I see 4100 rpm on the low side in 3rd and 4th gear and run through the traps at 5500 rpm in 4th. I shift into 4th just after the 1/8 mile so its in 4th gear essentially the entire last 1/8 mile.
Geesh, be careful with that area. Putting much of any timing to it before 5000-5400 will help you join the bent rod club. Seeing that you're dropping into the 4000's when you shift, I'd not be adding any timing. If anything, spin it to 6500 to drop the lower end to 5000.
 
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motorheadmike

Geezer
Nov 18, 2009
7,083
113
Ottawa, Ontario Canada
Mike is right.

Showed this to Natasha and she immediately frowned, glared at me, and in a very accusatory tone said: About what?

Ouffff GIF by memecandy
 

81cutlass

Comic Book Super Hero
Thread starter
Feb 16, 2009
3,279
113
Western MN
Showed this to Natasha and she immediately frowned, glared at me, and in a very accusatory tone said: About what?

Ouffff GIF by memecandy
You are welcome!!!

Geesh, be careful with that area. Putting much of any timing to it before 5000-5400 will help you join the bent rod club. Seeing that you're dropping into the 4000's when you shift, I'd not be adding any timing. If anything, spin it to 6500 to drop the lower end to 5000.

I was not aware timing in the sub 5k rpm was bendy rod territory. I know the max effort SBE guys spin the engines high and just ride the converter but didn't realize it had any correlation to timing and making the motor live.

I usually shift at 5800 because the factory rev limiter is set to 6000 and I just try not to smack the rev limiter. Never had a reason to change the rev limiter RPM.

I'll bump the rev limiter to 6500 and move the shift light to 6300. That should get the low RPM shift at 4600. If it's happy I might go a bit more RPM. I have BTR 660 valve springs so I shouldn't float the valves.

I get a bit sketched out spinning the motor that fast but Dad comes from the Diesel world and I spent my younger years with him telling me to not spin the engine so fast.


In other news I checked my injector flow rate in my tune (and it was 104 lb/hr) so somehow I knew my base pressure was 71ish PSI a few years back and never addressed it? I changed it to 62 PSI and set the flow rate to 94lb/hr. I tried getting the base pressure to 58 or 60 and it wouldn't go any lower. I think the stock 3/8 feed line that I am using as my return is too small, which explains why the vacuum side of the regulator doesn't work. At 15 inches of manifold vacuum it should reduce the fuel pressure to ~50 psi gauge which would be 60 PSI effective but it never goes below 60 which is a hint the return line is too small.

I have -6 from the tank to the firewall and -8 from there to the rails, and then -6 from the regulator to the ethanol content sensor and then 3/8 GM hardline back to the tank. I might have to think about using my current -6 feed and converting it to return and then pulling a new -8 all the way from the tank up to the rails.

Seems fishy though, I might toss a pressure gauge in the return line and see what's up.
 
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