Dyno tuned my Paxton '06 coupe today

[Nine Ball]

I had the guys at Late Model Racecraft in Houston ( Late Model Racecraft - Welcome ) do a dyno tune on my '06 Viper today.

Modifications:
Paxton supercharger with stock pulley and Split-Second (8.5 psi boost)
Custom 3" exhaust with high-flow cats (stock exhaust manifolds)
Computer tuning via SCT XCalibrator 2 tuner module and custom tuning software

Prior to tuning, the lower rpm was very lean and the throttle response was crappy. The engine did not rev smoothly in the midrange. This could also be felt when running the car hard. The custom tune added fuel in the lower rpm range, and added more timing at the higher rpm range. The result is now better drivability, smoother revving throughout the rpm range, and better throttle response at all rpm. It feels like a different car now, I'm pleased.

You must be registered for see images attach

Video: YouTube - Late Model Racecraft's 06 Supercharged Viper!

Next up, they will be pulling the engine out and building it to handle more boost. Plans call for forged pistons and rods, stock crank, and billet mains. I'd like to get 850-900 rwhp out of the Paxton. The engine will be built to handle 1200+ rwhp, just in case I decide to go twin turbos later on.

Tony

 

[shooter_t1]

I took mine there yesterday. Great bunch of guy's Some seriously fast cars at that shop. Steve made a video of mine also. I don't know if he's posted it yet though. Although aside from the wheels, pretty much the same as yours.

Gonna have them install a methanol kit next month.

 

[Nine Ball]

Haha, they told me my car's twin sister was in there earlier. I didn't realize it was you!

 

[shooter_t1]

Judging by the cars in your sig, you must have felt right at home

Did they fire up that black f-body(no front bumper)?. Absolutely bad*ss!.

 

[Tiago]

great results!

 

[hou99gts]

Rob, you were 1 minute from my house and didn't stop by? Shame on you! Same goes for you Tony! LOL!

I guess I need to stop by LMR now that they are a few Vipers up there..

 

[FastZilla]

Steve called me back today - said he couldn't tune mine because he had another B/W `06 on the dyno. Wholly crap

Well I'll just stink you all out at TWS running my 9.3:1 AF. I think my Vec2 scared him off. He used the terms "old" & "archaic" - might have said something about having to pull out the Rosetta stone to decode the Vec2. Hopefully he'll call back tomorrow and I can get it tuned on the way to the track.

 

[plumcrazy]

aint nothing wrong with 500rwtq @ 2500 rpms....

glad to hear it worked out for ya

 

[ViperGeorge]

Hard to tell from the graphs but what A/F are you at? What's the leanest number you hit under boost? Hope its in the 11's though. Mine hit 12.2 and it blew up at the track.

 

[Nine Ball]

Hard to tell from the graphs but what A/F are you at? What's the leanest number you hit under boost? Hope its in the 11's though. Mine hit 12.2 and it blew up at the track.

The dashed line is the optimal A/F ratio of 12.8 at wide open throttle. If you hit 12.2, that means your car was running richer than optimal. Usually going rich doesn't hurt, going lean will burn things up. Look at my A/F data, the tune in my car now is actually safer and it makes more power.

 

[mjorgensen Woodhouse]

The dashed line is the optimal A/F ratio of 12.8 at wide open throttle. If you hit 12.2, that means your car was running richer than optimal. Usually going rich doesn't hurt, going lean will burn things up. Look at my A/F data, the tune in my car now is actually safer and it makes more power.

WRONG, with stock internals you may see a power increase but anything over 12:1 is just insuring real trouble, and looking at the graph I would say you are.

IMHO of course, We have built 140+ Paxton systems and I know what will "live" and what won't...12.8:1 is an N/A ratio and that's it.

 

[Nine Ball]

Wow, what a somewhat rude response from a vendor. Look at my pre-tune A/F ratio, it has lived at that for over 6,000 miles now, including a few track days. My tune is now safer than it was before. But what does this shop know about forced induction, they have only built multiple 7-second quarter mile cars pushing 1800+ hp. Dozens of street cars putting down well over 1000 rwhp. How many cars at that level have you built at a Dodge dealership?

2001 Chevy Camaro Z28 - GM High-Tech Performance

 

[mjorgensen Woodhouse]

Wow, what a somewhat rude response from a vendor. Look at my pre-tune A/F ratio, it has lived at that for over 6,000 miles now, including a few track days. My tune is now safer than it was before. But what does this shop know about forced induction, they have only built multiple 7-second quarter mile cars pushing 1800+ hp. Dozens of street cars putting down well over 1000 rwhp. How many cars at that level have you built at a Dodge dealership?

2001 Chevy Camaro Z28 - GM High-Tech Performance

Sorry for the perceived rudeness, but the answer is NONE. We don't build drag cars we have to build cars that are reliable and safe. 12:1 is safe is all I'm saying and I think that most "tuners" on this site would say the same. I am sorry for sounding rude I was just trying to look out for you.

 

[Nine Ball]

FYI, I only mentioned the 12.8 line because the guy above had a hard time reading the graph. I mentioned the 12.8 dashed line as a reference, I didn't mean to say it was optimal for all combos. On dyno graphs, 12.8 is just typically the "optimal" line shown. My tune is in the 11-12 range for the most part. Compare the red (tuned) line to the blue line, do you not agree it is safer?

BTW, the guy who does the tunes here also did tunes at RSI and Hennessey for years prior to being at LMR. I should be okay, this combo is only temporary for a few more weeks.

 

[mjorgensen Woodhouse]

FYI, I only mentioned the 12.8 line because the guy above had a hard time reading the graph. I mentioned the 12.8 dashed line as a reference, I didn't mean to say it was optimal for all combos. On dyno graphs, 12.8 is just typically the "optimal" line shown. My tune is in the 11-12 range for the most part. Compare the red (tuned) line to the blue line, do you not agree it is safer?

BTW, the guy who does the tunes here also did tunes at RSI and Hennessey for years prior to being at LMR. I should be okay, this combo is only temporary for a few more weeks.

Enough said

 

[Magnus_]

Looks good Tony!

 

[FLATOUT]

Awesome Tony! Can't wait to slap a Paxton on mine! I need to get over and check that thing out. I need to give FR racing a call as well.

Andy Wheeler

 

[ViperGeorge]

Let me clarify my previous post. When my Paxton was first installed the A/F was around 11.5 or so at WOT. More fuel is safer for a blown application it keeps the internals cooler and helps prevent detonation. However it can raise the side sill heat because the cats are working harder. Given this I subsequently installed Random Tech high flow cats and Corsa exhaust to lower side sill temps. After doing this the A/F went to 12.1 or so at its leanest at WOT. At this ratio you will likely make more power but the risk is higher. The dyno shop (a very well known and respected one near me in New England) said it was fine at this ratio. They were wrong. The engine blew up on the track. After being torn down there were obvious signs of detonation. So if your in the 11s for A/F at WOT I would say you are probably ok. If you're anywhere in the 12s you're not. The car also will run leaner on the road under real load. It tends to run somewhat richer on a dyno, I guess because there isn't as much air being forced into the engine. Either way I would listen to Mark at Woodhouse or Dan at DC Performance. They know what they're talking about for Paxtonized Vipers. Good luck with the car.

 

[plumcrazy]

always trust the respected viper tuners on this site.

sorry to hear this. could it have been from the actual racing ?

 

[Tiago]

12.8 is LEAN under boost

 

[2002_Viper_GTS_ACR]

TRUST mjorgensen ...He knows *** he is talking about.. His guidance is invaluable. He doesnt like to fight/aruge, so if you push him in a corner he'll bow out gracefully... but you will have turned off an excellent source of knowledge. Expand your A/F graph or pass along the dyno files to someone who can (just takes a free download from dynojet), and repost the bigger graph. A/F is critical, my gen 2 paxton went Kaboom because of how wrong it was, my gen 3 has 26k total miles on it ALL under boost (thanks to Mjorgensen and Woodhouse's Paxton install) and it makes 700+ rwhp. (and DC Performance.. woops.. left off the great tuning guru in my koodos)

No one is trying to fight with you, just trying to keep you safe. If A/F is not tuned right, you can have an unfortunate outcome that no one wants to see you have.

Jon

 

[Jroc]

12.8 is crazy lean for FI

 

[Nine Ball]

Where are you guys seeing 12.8? That is just a reference line on the graph, not the A/F ratio. READ the entire post!

 

[Bobpantax]

I had the guys at Late Model Racecraft in Houston ( Late Model Racecraft - Welcome ) do a dyno tune on my '06 Viper today.

Modifications:
Paxton supercharger with stock pulley and Split-Second (8.5 psi boost)
Custom 3" exhaust with high-flow cats (stock exhaust manifolds)
Computer tuning via SCT XCalibrator 2 tuner module and custom tuning software

Prior to tuning, the lower rpm was very lean and the throttle response was crappy. The engine did not rev smoothly in the midrange. This could also be felt when running the car hard. The custom tune added fuel in the lower rpm range, and added more timing at the higher rpm range. The result is now better drivability, smoother revving throughout the rpm range, and better throttle response at all rpm. It feels like a different car now, I'm pleased.

You must be registered for see images attach

Video: YouTube - Late Model Racecraft's 06 Supercharged Viper!

Next up, they will be pulling the engine out and building it to handle more boost. Plans call for forged pistons and rods, stock crank, and billet mains. I'd like to get 850-900 rwhp out of the Paxton. The engine will be built to handle 1200+ rwhp, just in case I decide to go twin turbos later on.

Tony

Based on the chart above, the red broken reference line is at 13/1 A/F or just below it. The run evidenced by the blue line is too lean in general and way too lean from 5000RPM up. In the run evidenced by the red line you are above 12/1 for a good part of it and from about 5650 RPM until pedal lift at 6000 RPM you are well over 12.5/1. Look in particular from 5750 to 6000. I assume that you have stock internals. If so, you need your tune revised if you want the engine to last under spirited use. I assume that you are aware of the DC Performance tunes available. I have their blower/track tune. It has proved flawless and safe.

 

[Nine Ball]

My engine has nearly 6,000 miles of spirited abuse with the blower. Including three track weekends. That was also with the old (blue) tune on it. The new (red) tune is actually safer. When you actually zoom in on the A/F chart, most of the line is under 12.0. This graph is distorted because it is shrunk down. The lower rpm range isn't seeing boost yet, remember this is a centrifugal blower and it requires higher rpm to build boost. Those curves down there are mostly all-motor, and still using the stock fuel pump. Then the curve dips down, that is when the FMU senses boost and the external inline Paxton fuel pumps kick on.

 

[Bobpantax]

My engine has nearly 6,000 miles of spirited abuse with the blower. Including three track weekends. That was also with the old (blue) tune on it. The new (red) tune is actually safer. When you actually zoom in on the A/F chart, most of the line is under 12.0. This graph is distorted because it is shrunk down. The lower rpm range isn't seeing boost yet, remember this is a centrifugal blower and it requires higher rpm to build boost. Those curves down there are mostly all-motor, and still using the stock fuel pump. Then the curve dips down, that is when the FMU senses boost and the external inline Paxton fuel pumps kick on.

Thanks for the clarification. The red tune is certainly safer. But even if the chart is a bit distorted, from 5750 RPM up to 6000 RPM the red tune seems too lean. I would guess that you rarely, if ever let the RPMs get that high on the track. Am I correct?

 

[ViperGeorge]

I have several dyno runs on my car. Some before and some after the addition of the new exhaust. If I can figure out how to get them scanned I will post them here. My graphs have a much finer scale than the ones posted here so it is easier to see exact A/F at any RPM. Before the exhaust mods the car was running in the 11s after 3200 RPM (when boost kicks in on a Paxton). From 3700 RPM up it was below 11.5:1 to lift off. Average about 11.2:1. I actually thought it was too rich as it did smoke some on the track. It was safe though.

After the exhaust mods the A/F was in the high 11s hitting 12.2:1 at 5100 RPM. Remember that this will lean out further on real roads with more air being forced into engine via the ram air effect. Also it will get leaner as the car heat soaks. I can actually see this on three dyno runs before exhaust mods. A/F got leaner after each run but was still plenty safe.

Running leaner may be ok for short bursts and for tracks with lots of twisties and short straights as you're not in boost for long periods. However if you run it for extended periods on warm days on tracks with long straights (like some super speedways - Pocono, MIS, Daytona, etc.) then you have a higher likelihood for problems. My blow up took place on one of these tracks that has extremely long straights. Now I'm doing forged internals and have already had DC Performance redo the PCM to be richer.

Again I'm not saying you are in fact running lean, I can't honestly tell because the scale on the dyno run is not fine enough. I would call the shop and ask if they can print you a graph of just A/F with a finer scale. Each block on my graphs is 0.1 That way you would know for sure. But if you are in the 12s on a dyno I would say you are in fact too lean. That's from a rather expensive lesson learned. Good luck either way.

 

[Late Model Racecraft]

WRONG, with stock internals you may see a power increase but anything over 12:1 is just insuring real trouble, and looking at the graph I would say you are.

IMHO of course, We have built 140+ Paxton systems and I know what will "live" and what won't...12.8:1 is an N/A ratio and that's it.

This car came to us with an A/F in the range of 12.4 and left with an average A/F of 11.6. We actually picked up HP by making the car safer. Hope that helps. Please let me know if you would like me to make the A/F graph alot larger for yalls viewing needs.

 

[eucharistos]

This car came to us with an A/F in the range of 12.4 and left with an average A/F of 11.6. We actually picked up HP by making the car safer. Hope that helps. Please let me know if you would like me to make the A/F graph alot larger for yalls viewing needs.

welcome aboard

 

[2002_Viper_GTS_ACR]

This car came to us with an A/F in the range of 12.4 and left with an average A/F of 11.6. We actually picked up HP by making the car safer. Hope that helps. Please let me know if you would like me to make the A/F graph alot larger for yalls viewing needs.

Why not. I'd be interested in seeing the details of it. Thanks!

Jon