first n2o passes do not result in new best ET - Chevelle Tech
Performance Our High Performance area

 10Likes
Reply
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 25 (permalink) Old Nov 26th, 19, 6:30 PM Thread Starter
Tech Team
Bob
 
Join Date: Jul 2010
Location: Lake St Louis, Mo
Posts: 624
first n2o passes do not result in new best ET

Where do I begin ... this could be long.
Fall 2019 weather in the metro St Louis Area has been awful and at least 4 race dates I intended to make my first n2o passes were cancelled.
I cruise the internet and saw that a mere 6 hours away in Tulsa they were having a test and tune on 11/24. I rented a trailer and made a day trip out of it.
The game plan going in.
I put together a standalone fuel side with holley blue pump and Quickfuel regulator to deliver VP 110 gas from a 1 gallon cell. The nitrous kit is an NX Express hitman plate, 100 hp jets, and maximizer EZ progressive controller. The timing is contolled bu MSD digital 6 plus and the plugs were NGK R5671A-9
I had hoped for at least 2 passes and that I'd be in the 9s for sure. the thought was 2.5 second delay and pull 3.5* of timing. the progressive starts at 20% and brings in the rest over the time. If the track could hold 2.5 then I wanted to drop it to 1.5.
What happened:
While I was swapping a few plugs and getting into race trim a guy started talking to me. As he was about to leave I asked how the track looked. He said the small tire guys were struggling. I run a 255/60 drag radial so I immediately went into concern mode. My car has had issues open headers at times with tire spin. Adding a 100 shot made me feel like that would be a huge concern. The new game plan was to set the progressive to 4 seconds on pass one.
Pass 1: pull 3.5* with 4 second ramp on progressive. forgot to data log
result - 1.577, 4.305,6.538-110mph,10.096-138.00 mph
Pass 2: pull 3.5* with 3 second ramp
result: 1.552,4.294,6.535-109.50mph,10.108-137.61mph
I started the data logger but shut the car off before ending the logging session so I could get a good plug read. this caused fitech to not log the that or any other passes for the day. I had to delete a file to clear up but not until I was home.
While in the pits getting a second bottle ready they said 20 minutes left for the day. This was roughly 75 minutes earlier than it was supposed to close. there was no chance to swap jets and turn the car around.
pass 3: pull 3* and 2.5 second ramp
result: 1.55,4.33x,6.591-109.05mph,10.169-137.58
drove straight back to the lanes to make a 4th run NA.
Pass 4: NA, no timing pulled
result: 1.56,4.325,6.660-104.9,10.408-130.87
I made a video on the way there.
https://youtu.be/41E4oE5N7xg
Initial reaction video:
https://youtu.be/5rGdkvi5Q7s
deeps thoughts postmortem:
1. Was I really getting 100 HP?
2. Does the MSD really pull the correct timing based on the dial setting (was not tested)? could 3* timing when adding 20% power inthis case 20 HP actually slow the 60' over NA?
3. Do I need a taller hood or should I cut a hole and add a scoop like Troy Lacrone and many other n2o racers.
4. How is my NA 660" only 3 tenths slower when NA from any pass that should have been full power on the nitrous varying from 4-2 seconds?

Bob
1972 Nova
496 AFR315
Straub Custom HR 258/260 108 lsa
MT 255x60x15 drag radials, Fitech 30012 power adder
1/4 10.067 10/24/2018
1/4 138 MPH **NEW** 11/24/2019 (100 shot)
60' 1.446 10/24/2018
Best 1/8 - 6.404 10/24/2018
Best 1/8 110.11 MPH **NEW** 11/24/2018
Dragweek 2015,2017,2018 SME
2016,2017 RMRW 11.0 index
Supernova72 is offline  
Sponsored Links
Advertisement
 
post #2 of 25 (permalink) Old Nov 26th, 19, 7:00 PM
Tech Team
 
Join Date: Feb 2019
Posts: 905
Re: first n2o passes do not result in new best ET

Anytime I used to use n2o I always picked up a lot. I was running a 396 in the car and it was hitting 11.70's N/A and with a 100 shot the car ran 10.90's, with that said it is hard to hook a lot of power with drag radials IMO. On a small shot I never retard the timing as I don't think it's needed at that amount. Also is your car setup for n20 (camshaft) as that makes a difference also, I see your cam is on a 108 LCA and that makes a big difference. my old 358 SBC was in the 11.70's N/A a few years ago with a 110 LCA cam and with a 200 shot on the car it ran the best of [email protected], that was with a cheater system. Too bad where I live filling the bottles is cost prohibitive so all the n20 sits in the basement inc. the fogger I got this year.
68Chevele is offline  
post #3 of 25 (permalink) Old Nov 26th, 19, 7:57 PM
Lifetime Premium Member
MARK
 
Join Date: Jul 2007
Location: CO/TO
Posts: 4,288
Re: first n2o passes do not result in new best ET

What is your top ring gapped at?
dragginwagon406 likes this.

Machined GM production heads
Oil pan modifications
VORTECPRO is offline  
 
post #4 of 25 (permalink) Old Nov 26th, 19, 8:19 PM
Lifetime Premium Member
Jason
 
Join Date: Sep 1998
Location: Highland Village TX, USA
Posts: 3,138
Re: first n2o passes do not result in new best ET

On the nitrous system, what nitrous/fuel jetting and fuel pressure?

What was base timing that you were pulling 3.5 deg. from?

Jason Gore
AKA DragRacer
Naturally Aspriated 450 SBC - 915 HP / 714 lb-ft
3370 lbs
1.36 - 60', 5.93 @ 116.7 MPH - 1/8th
DragRacer is offline  
post #5 of 25 (permalink) Old Nov 26th, 19, 8:31 PM
Team Member
George
 
Join Date: Feb 2010
Location: Upper Sandusky, Ohio
Posts: 2,755
Re: first n2o passes do not result in new best ET

You were ramping it in way too slow...if you think about it, your 1/8 it 6 secs and your ramp was over half of that. Nitrous makes the most difference right off the line.

Also depending on the kit you have the factory tunes are pretty fat. Mine is a cheater plate which called for 53/47 fuel and nitrous for 100 hp...a/f was 10.0 all the way down track. Went to 47/53 and lowered fp down to 5.5 and got to 12.0..dropped the fuel jet to 45 and got to 12.5. Reading the plugs I started pulling timing at 4* with my msd. Plugs wanted 2* more.

I have a NX progressive box that only has the time adjustment. Started mine at 1.5 sec which is almost my 60. Car launched good then went sideways at the 60.

Last time out on motor was 7.40s. With a 1.61 60. Turned the progressive down to 1 sec with only about 850 psi. Launched the spun then hooked...same 1.61 60 6.94 @100 and [email protected] Pretty cold nite.

But ramp that nos in alot sooner and you should see a better result.

'71 Malibu
3580 #, Carbed 6.0l LS swap in process
T-350, PTC 9" converter, 12 bolt, spool, 3.90 gears, MT ET R 275/60/15

355 [email protected]
125 [email protected]
388 Mud Motor- [email protected]
100 shot [email protected]
'72 Greenbrier Wagon: 454, 700R4, 12 bolt with 3.73
Geo71 is online now  
post #6 of 25 (permalink) Old Nov 27th, 19, 5:55 AM Thread Starter
Tech Team
Bob
 
Join Date: Jul 2010
Location: Lake St Louis, Mo
Posts: 624
Re: first n2o passes do not result in new best ET

**correction NX Express mainline**

Quote:
Originally Posted by VORTECPRO View Post
What is your top ring gapped at?
.026, I am trying to confirm the rings and their spec but when it went to together it was for a 200 shot. the pistons have a 1.5/1.5/3mm

Quote:
Originally Posted by DragRacer View Post
On the nitrous system, what nitrous/fuel jetting and fuel pressure?
The kit calls for 52 - n2o, 47 fuel @ 8PSI fuel pressure

What was base timing that you were pulling 3.5 deg. from?
The kit calls for 52 - n2o, 47 fuel @ 8PSI fuel pressure
Timing was not touched since summer NA passes and that was 36-37* if I recall. I will check it when I test the MSD later today.

Quote:
Originally Posted by 68Chevele View Post
Anytime I used to use n2o I always picked up a lot. I was running a 396 in the car and it was hitting 11.70's N/A and with a 100 shot the car ran 10.90's, with that said it is hard to hook a lot of power with drag radials IMO. On a small shot I never retard the timing as I don't think it's needed at that amount. Also is your car setup for n20 (camshaft) as that makes a difference also, I see your cam is on a 108 LCA and that makes a big difference. my old 358 SBC was in the 11.70's N/A a few years ago with a 110 LCA cam and with a 200 shot on the car it ran the best of [email protected], that was with a cheater system. Too bad where I live filling the bottles is cost prohibitive so all the n20 sits in the basement inc. the fogger I got this year.
Chris knew I wanted up to a 200 shot of n2o and despite the LSA value the cam he came up with is said to take a 400 shot. My car unloads a little fast NA so I wanted to be conservative with how quick it came in but the car has been 10.20s-10.30s NA in similar DA in the past. my 330 was about the same whether I was all in at 2 seconds, 4 seconds, or NA.

the time slips are first to last from right to left. I wish the ink was darker.
Attached Thumbnails
Click image for larger version

Name:	tulsa_slips.jpg
Views:	15
Size:	48.5 KB
ID:	609326  

Bob
1972 Nova
496 AFR315
Straub Custom HR 258/260 108 lsa
MT 255x60x15 drag radials, Fitech 30012 power adder
1/4 10.067 10/24/2018
1/4 138 MPH **NEW** 11/24/2019 (100 shot)
60' 1.446 10/24/2018
Best 1/8 - 6.404 10/24/2018
Best 1/8 110.11 MPH **NEW** 11/24/2018
Dragweek 2015,2017,2018 SME
2016,2017 RMRW 11.0 index
Supernova72 is offline  
post #7 of 25 (permalink) Old Nov 27th, 19, 6:55 AM
Lifetime Premium Member
 
Join Date: Oct 2005
Location: CT,USA
Posts: 13,067
Re: first n2o passes do not result in new best ET

Quote:
Originally Posted by Supernova72 View Post
Where do I begin ... this could be long.
Fall 2019 weather in the metro St Louis Area has been awful and at least 4 race dates I intended to make my first n2o passes were cancelled.
I cruise the internet and saw that a mere 6 hours away in Tulsa they were having a test and tune on 11/24. I rented a trailer and made a day trip out of it.
The game plan going in.
I put together a standalone fuel side with holley blue pump and Quickfuel regulator to deliver VP 110 gas from a 1 gallon cell. The nitrous kit is an NX Express hitman plate, 100 hp jets, and maximizer EZ progressive controller. The timing is contolled bu MSD digital 6 plus and the plugs were NGK R5671A-9
I had hoped for at least 2 passes and that I'd be in the 9s for sure. the thought was 2.5 second delay and pull 3.5* of timing. the progressive starts at 20% and brings in the rest over the time. If the track could hold 2.5 then I wanted to drop it to 1.5.
What happened:
While I was swapping a few plugs and getting into race trim a guy started talking to me. As he was about to leave I asked how the track looked. He said the small tire guys were struggling. I run a 255/60 drag radial so I immediately went into concern mode. My car has had issues open headers at times with tire spin. Adding a 100 shot made me feel like that would be a huge concern. The new game plan was to set the progressive to 4 seconds on pass one.
Pass 1: pull 3.5* with 4 second ramp on progressive. forgot to data log
result - 1.577, 4.305,6.538-110mph,10.096-138.00 mph
Pass 2: pull 3.5* with 3 second ramp
result: 1.552,4.294,6.535-109.50mph,10.108-137.61mph
I started the data logger but shut the car off before ending the logging session so I could get a good plug read. this caused fitech to not log the that or any other passes for the day. I had to delete a file to clear up but not until I was home.
While in the pits getting a second bottle ready they said 20 minutes left for the day. This was roughly 75 minutes earlier than it was supposed to close. there was no chance to swap jets and turn the car around.
pass 3: pull 3* and 2.5 second ramp
result: 1.55,4.33x,6.591-109.05mph,10.169-137.58
drove straight back to the lanes to make a 4th run NA.
Pass 4: NA, no timing pulled
result: 1.56,4.325,6.660-104.9,10.408-130.87
I made a video on the way there.
https://youtu.be/41E4oE5N7xg
Initial reaction video:
https://youtu.be/5rGdkvi5Q7s
deeps thoughts postmortem:
1. Was I really getting 100 HP?
2. Does the MSD really pull the correct timing based on the dial setting (was not tested)? could 3* timing when adding 20% power inthis case 20 HP actually slow the 60' over NA?
3. Do I need a taller hood or should I cut a hole and add a scoop like Troy Lacrone and many other n2o racers.
4. How is my NA 660" only 3 tenths slower when NA from any pass that should have been full power on the nitrous varying from 4-2 seconds?
Bob, so going by your post signature, you went from 1.4 second short times naturally aspirated, to a 1.56 with the spray? Am I getting that correct? I don't think you explained that, (unless I missed it). Can you say if you were getting tire spin off the line, or no? I have to ask you that because I don't want to assume that the slower 60 foot time was actually due to being down on power off the line.

If you're sure it wasn't due to tire spin, then I'd be inclined to conclude that you pulled too much ignition timing, or at least you had the advance curve coming in too late. I'd also want to ask you if you have main jet extensions installed in the secondary carb bowl. If you don't, then maybe the jets are being momentarily starved for fuel. Although Imust admit that I'm not at all sure if that applies just as much to a motor on spray as it sometimes can on a N/A motor.

But if it's possible that you did get tire spin off the line, then the first question I would ask is exactly what tire pressure were you running, and what drag radials do you use?

Note: based on what's been said in this thread so far, I'm leaning to the ignition timing changes you've made as being the culprit but I think it would be a good thing to rule out the other simple things I've mentioned first. I like to start with simple things first to make sure I don't end up chasing my tail

70 Chevelle SS clone (632 CI powered).
BillyGman is offline  
post #8 of 25 (permalink) Old Nov 27th, 19, 9:29 AM
Tech Team
 
Join Date: Aug 2017
Posts: 58
Re: first n2o passes do not result in new best ET

Make sure you are not triggering your timing retard until after the progressive is flowing a substantial amount of nitrous.

Grant

Grant
website-
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

We make your non-adjustable clutch...ADJUSTABLE!
sr530 is offline  
post #9 of 25 (permalink) Old Nov 27th, 19, 9:38 AM Thread Starter
Tech Team
Bob
 
Join Date: Jul 2010
Location: Lake St Louis, Mo
Posts: 624
Re: first n2o passes do not result in new best ET

Quote:
Originally Posted by BillyGman View Post
Bob, so going by your post signature, you went from 1.4 second short times naturally aspirated, to a 1.56 with the spray? Am I getting that correct? I don't think you explained that, (unless I missed it). Can you say if you were getting tire spin off the line, or no? I have to ask you that because I don't want to assume that the slower 60 foot time was actually due to being down on power off the line.

If you're sure it wasn't due to tire spin, then I'd be inclined to conclude that you pulled too much ignition timing, or at least you had the advance curve coming in too late. I'd also want to ask you if you have main jet extensions installed in the secondary carb bowl. If you don't, then maybe the jets are being momentarily starved for fuel. Although Imust admit that I'm not at all sure if that applies just as much to a motor on spray as it sometimes can on a N/A motor.

But if it's possible that you did get tire spin off the line, then the first question I would ask is exactly what tire pressure were you running, and what drag radials do you use?

Note: based on what's been said in this thread so far, I'm leaning to the ignition timing changes you've made as being the culprit but I think it would be a good thing to rule out the other simple things I've mentioned first. I like to start with simple things first to make sure I don't end up chasing my tail
My best NA pass in my signature was with a 1050 4150 carb in roughly -200' DA. I made a pass with the Fitech in similar DA this spring and went 10.12.
At my last home event on 9/15/19 the car went 1.537,4.357,6.709-104.74 mph,10.457-130.94 mph @ 2400' DA.

At Tulsa my car went 1.56,4.325,6.660-104.9,10.408-130.87 NA @ 1500' DA
My 50' times same day with n2o 1.55 and without 1.56.
Between my ass and the footage it doesn't appear to spin.

Drag radial is the SS MT 255/60/15 @ 15 psi. I usually run16 but the tought of the track not being there I went down a pound.

**one thing not mentioned yet (shame on me)** within the fitech software I set the target WOT from 12.8 NA to 12.2 for n2o. On pass 3 I bumped down to 11.85 with the timing change to -3*. Since I botched the data logging I have nothing bu the in car video which I hope I can zoom in on the handheld.

Bob
1972 Nova
496 AFR315
Straub Custom HR 258/260 108 lsa
MT 255x60x15 drag radials, Fitech 30012 power adder
1/4 10.067 10/24/2018
1/4 138 MPH **NEW** 11/24/2019 (100 shot)
60' 1.446 10/24/2018
Best 1/8 - 6.404 10/24/2018
Best 1/8 110.11 MPH **NEW** 11/24/2018
Dragweek 2015,2017,2018 SME
2016,2017 RMRW 11.0 index
Supernova72 is offline  
post #10 of 25 (permalink) Old Nov 27th, 19, 11:47 AM Thread Starter
Tech Team
Bob
 
Join Date: Jul 2010
Location: Lake St Louis, Mo
Posts: 624
Supernova72 is offline  
post #11 of 25 (permalink) Old Nov 27th, 19, 11:52 AM Thread Starter
Tech Team
Bob
 
Join Date: Jul 2010
Location: Lake St Louis, Mo
Posts: 624
Re: first n2o passes do not result in new best ET

Quote:
Originally Posted by sr530 View Post
Make sure you are not triggering your timing retard until after the progressive is flowing a substantial amount of nitrous.

Grant
Timing retard is getting signal from wot switch and in this case only 20% of 100.

Bob
1972 Nova
496 AFR315
Straub Custom HR 258/260 108 lsa
MT 255x60x15 drag radials, Fitech 30012 power adder
1/4 10.067 10/24/2018
1/4 138 MPH **NEW** 11/24/2019 (100 shot)
60' 1.446 10/24/2018
Best 1/8 - 6.404 10/24/2018
Best 1/8 110.11 MPH **NEW** 11/24/2018
Dragweek 2015,2017,2018 SME
2016,2017 RMRW 11.0 index
Supernova72 is offline  
post #12 of 25 (permalink) Old Nov 27th, 19, 12:50 PM
Lifetime Premium Member
 
Join Date: Oct 2005
Location: CT,USA
Posts: 13,067
Re: first n2o passes do not result in new best ET

Quote:
Originally Posted by Supernova72 View Post
Hmmm, yep you're right. No tire spin seen there. Just for haha's, what rear gear and trans first gear ratios do you have? And what about vehicle weight? I'm just trying to get a good sense of your entire combination

70 Chevelle SS clone (632 CI powered).
BillyGman is offline  
post #13 of 25 (permalink) Old Nov 27th, 19, 12:53 PM
Lifetime Premium Member
Jason
 
Join Date: Sep 1998
Location: Highland Village TX, USA
Posts: 3,138
Re: first n2o passes do not result in new best ET

From the videos, doesn't look like it is spinning at all. If you can turn the N2O on sooner you will have your 9.

Jason Gore
AKA DragRacer
Naturally Aspriated 450 SBC - 915 HP / 714 lb-ft
3370 lbs
1.36 - 60', 5.93 @ 116.7 MPH - 1/8th
DragRacer is offline  
post #14 of 25 (permalink) Old Nov 27th, 19, 3:46 PM Thread Starter
Tech Team
Bob
 
Join Date: Jul 2010
Location: Lake St Louis, Mo
Posts: 624
Re: first n2o passes do not result in new best ET

Quote:
Originally Posted by BillyGman View Post
Hmmm, yep you're right. No tire spin seen there. Just for haha's, what rear gear and trans first gear ratios do you have? And what about vehicle weight? I'm just trying to get a good sense of your entire combination
3.25 rear gear, factory th400 first can't remember if that's 2.48 or 2.51. the car weighed about 3550 before adding the bottle and standalone kit.
68Chevele likes this.

Bob
1972 Nova
496 AFR315
Straub Custom HR 258/260 108 lsa
MT 255x60x15 drag radials, Fitech 30012 power adder
1/4 10.067 10/24/2018
1/4 138 MPH **NEW** 11/24/2019 (100 shot)
60' 1.446 10/24/2018
Best 1/8 - 6.404 10/24/2018
Best 1/8 110.11 MPH **NEW** 11/24/2018
Dragweek 2015,2017,2018 SME
2016,2017 RMRW 11.0 index
Supernova72 is offline  
post #15 of 25 (permalink) Old Nov 27th, 19, 3:53 PM Thread Starter
Tech Team
Bob
 
Join Date: Jul 2010
Location: Lake St Louis, Mo
Posts: 624
Re: first n2o passes do not result in new best ET

I feel like the MSD is why the results aren't there. I activated the WOT switch while checking the timing a little while ago and it was 36* full advance and it dropped 3* but it was popping a bit when the MSD dropped the timing. I think that is the soft touch. Either way it didn't sound clean. Unfortunately it will likely be months (early 2020) before I run it again.

If the track would have been fully prepped I would have had no issues trying a 100% from the hit but my car unloads a bit faster than I'd like and the fear was blowing the tires off. that was the point of the maximizer EZ, come in when I can use it all.

Bob
1972 Nova
496 AFR315
Straub Custom HR 258/260 108 lsa
MT 255x60x15 drag radials, Fitech 30012 power adder
1/4 10.067 10/24/2018
1/4 138 MPH **NEW** 11/24/2019 (100 shot)
60' 1.446 10/24/2018
Best 1/8 - 6.404 10/24/2018
Best 1/8 110.11 MPH **NEW** 11/24/2018
Dragweek 2015,2017,2018 SME
2016,2017 RMRW 11.0 index
Supernova72 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome