Paxton vs PD Blower - my Z06 vs my Viper

[Nine Ball]

As a continued discussion from this previous thread, I would like to ponder some ideas about putting my Viper back on top of my Z06, in a roll-on race.

Current situation, I ran my Z06 against my Viper (buddy driving one vehicle) and the Z06 put 2.5-3 car lengths on the Viper from a 60-160 mph roll. This was when the Z06 was making 60 less rwhp than it does now. When we nail it at 60 (whether we use 2nd or 3rd gear, similar outcome) the Z06 would instantly jump out one car length. The Viper would begin to creep up on the Z06, until it had to shift at 6K rpm. That would result in another car length for the Z06, as it merrily pulls to 7K rpm. Same thing happens between each gear.

Info on the cars:

2006 Viper coupe
Paxton supercharger (stock pulley)
9 psi boost
Stock exhaust manifolds, custom catback with high-flow cats
Custom dyno tuned with SCT software
3500 lbs

2009 Corvette Z06
MagnaCharger TVS2300 supercharger w/ 3.4 pulley (3.6 was stock)
8 psi boost
1-7/8 longtube headers, with cats, stock mufflers
Custom dyno tuned with HPT software
3250 lbs

As you can see, the cars are closely modded. Here is the dyno graph comparison as it sits today. I will run them again soon, but the Z06 will likely put 4-5 car lengths on the Viper now, since I added roughly 60 rwhp to it over the weekend with headers and a pulley. I put colored dots on the graphs, showing the racing rpm powerband for each car. Both cars currently average 600 rwhp in that range, but the Z06 is always above 600 rwhp. That is a huge difference!

It seems I need to boost the Viper up to at least 700 rwhp, but also need better midrange boost too. Some say pulley + restrictor plate. I simply don't have enough feedback on what exactly to use for this. Who sells a kit that will deliver another 40-50 rwhp, while also improving midrange boost?

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Here is how my Z06 compares to a stock ZR1:

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So, what is it going to take to put the Viper back on top in this match up? Hopefully not something extreme like a built engine and turbos. I'd like to use the Paxton, if possible.

Tony

 

[VIPER GTSR 91]

The Vette forum guys will love this. Your 250 lbs. more weight does not help in the Viper. How about different gearing? Nice cars !!

 

[Phun70]

Gearing! for sure!

 

[Nine Ball]

Gearing won't make a difference when roll racing. It is a pure HP battle at that point (and wind drag, and weight). Putting a more aggressive gear in the Viper would just mean shifting earlier, with likely the same result at the end. I'm mostly intrigued by people mentioning smaller blower pulleys and restrictor plates, and if anyone has any before/after dynos of that on a Viper.

This comparison just proves that dyno numbers do not win races. Look at the area under the HP/TQ curves for that roots blower. Someone needs to build a roots kit for the SRT-10.

 

[V10TT]

Nine ball, try plotting a graph of each car of rwhp vs. mph. This will show the difference clearly.
It will take into account the different gears, and the diffrent red lines.

For example at 60 mph both cars in 2nd gear, the viper is at 4100 rpms, and the Z06 is at 4650 rpms.
Look at the HP on the graph for each car at that point(beginning of the race).
Viper is making 440 rwhp, the Vette is making 520 rwhp, get the picture?
Also the vette can pull the gears a little longer than the Viper, that also helps it out.

AT 130 mph, both cars in 4th gear, the Viper is at 5000 rpms making 560 rwhp, the z06 because of its 3.42 gearing is at 5600 rpms making 580 rwhp...

Gears will not help the viper. It will make you shift earlier than now and as soon as you grab 5th gear about at 125 mph, the z06 will just be getting out of third gear and into 4th. Viper in 5th vs. the Z06 in 4th... I'm sure you get the picture...

I think one of the problems is the SC paxton car by the time it gets into the race is probably making less hp than what it did on the dyno, and it probably losses some more in the 4th gear pull.

What about Water **** injection. It will cool the intake charge a bunch, allow you to run more timing, and make consistent horsepower.

 

[V10TT]

Usually trap speed tells the story.The Z probably should trap 135-137 mph in the 1/4 as it seats now with more hp.
Will the viper break 130 traps in the 1/4 with that set up?

 

[georgethedog]

Keep racing them... the Chevy will fall apart soon and then the Viper will win...

 

[Bobpantax]

Please post the difference, if any, in the transmission gear ratios between the two cars. Many people talk about the differential ratio but, to my knowledge, no one has experimented with the transmission ratios to maximize the sweet spots/shift points for a Paxtonized Viper. I know that when I changed out my fifth gear from .74 to .8 and my sixth from .5 to .63 it made a world of difference on the top end of things.

 

[ROCKET62]

Maybe the Paxton experts can chime in on your boost level. It appears to me that at 3000 rpm your only adding 2 lbs of boost and somewhere near 6 lbs at 5000 rpm. I understand the differences between the centrifugal vs roots type blowers, but 2 lbs of boost at 3000 rpm's seems low

 

[Roysviper]

Get rid of the Paxton and get a ROE!!!!

 

[rw99]

Maybe the Paxton experts can chime in on your boost level. It appears to me that at 3000 rpm your only adding 2 lbs of boost and somewhere near 6 lbs at 5000 rpm. I understand the differences between the centrifugal vs roots type blowers, but 2 lbs of boost at 3000 rpm's seems low

This really is a cool comparison, between the V8+Roots blower and the V10+centrifugal... we're all used to seeing SBC, Ford, and Hemi V8s and the impressive low rpm rwtq for positive displacemtnt roots/screw blowers. Much more area under the torque curve when compared to centris with same peak boost levels. Here's a case where the V10 already makes a bunch of grunt down low, and with the centri blower added ends up looking very similar to the magnacharged V8. I'd think that we're looking at or near the limit of useable power with those torque curves, where traction becomes limiting. The roll-on comparison makes that less of an issue, though...

For V8's, the conventional wisdom is that the fastest drag cars will have big centrifugal blowers, appropriately mated to stroked and/or bored motors. Moving more air at the same psi. I'm not acquainted with the Paxton line for Vipers, so I don't know if they have larger centris available.

The drive pulley swap on a centri is obviously the quickest route to increased boost, with re-tuning of course. And as V10TT mentioned, not a bad time to consider adding a methanol injection system. It might be instructive to log both cars' knock retard/timing during your runs; it's possible that the Viper is pulling some timing while the Vette isn't...

The Vette will always pull that instantaneous leap in your roll-ons, I think, because of its FI delivery... nearly instantaneous delivery of boost.

 

[ILLSMOQ]

Get rid of the Paxton and get a ROE!!!!

What a great idea

 

[SquadX]

Great comparison. Z06is making more power under the curve which wins races. Not peak power which you have to shift when it's reached. Also the vets rpm range is what makes another big difference. Because as you stated the viper will catch up/pull on the Z06 until it has to shift. Ain't no getting away from that. I'd love to see this same comparison with a roe viper thrown in.

 

[Nine Ball]

Nine ball, try plotting a graph of each car of rwhp vs. mph.

Good point, I'll do that next time I visit the shop. I'll be getting a tune on my CTS-V in the next couple weeks, adding a pulley/cam to it too.

Will the viper break 130 traps in the 1/4 with that set up?

My Viper's highest trap was 134.8 mph, but it usually averages around 132-133. The higher trap was a cool night, long cool down period on the engine. Z06 trapped 125 when it was 100% stock, I'd expect mid/high 130s no prob now.

Please post the difference, if any, in the transmission gear ratios between the two cars.

Both cars are still on factory, unmolested trannys.

2006 Viper = T56
2009 Corvette = TR6060

The Viper is a huge pig in 5th gear, I learned that at the Texas Mile event. It went 180 mph there, the same as stock ZR1's were running on the same weekend. 1-4 gears are a blast, 5th was horrible with the rpm drop and not much boost. Felt like slow cruise control on the big end of the track. I'm thinking the Z06 might go 185-190 no problem, and I hope to find out in March. It also has the crappy 5th gear, but since it makes full boost at 2.5K rpm, it isn't as affected as the Paxton is.

Methanol kit has indeed crossed my mind - for both vehicles. I'd still prefer to rely on a mechanical fix though, with the **** being a secondary fix.

Tony

 

[SquadX]

Also to the point of the Paxton only making 2lbs at 2k. Sunds about right as my old gts only made 4-5 lbs at 5800 rpms. I think this is were head cam work work so well with the Paxton cars as your getting the power of a NA car down lie with the power pull of a blower up top.

 

[coupe]

...I'd still prefer to rely on a mechanical fix though, with the **** being a secondary fix.

Twin turbos would be a mechanical fix, wouldn't they?

 

[Roysviper]

Twin turbos would be a mechanical fix, wouldn't they?

NOW YOUR TALKIN!!!

 

[plumcrazy]

water/**** would be a last resort for me. id stay away from it unless you really have to.

 

[ViperPWR]

You can also look at the tune. Unless both are dialed to the same timing and AFR you are not comparing things on an even playing field. There are a lot of variables in a tune....

The added weight of the Viper doesn't help at all....

 

[Bobpantax]

A check of the gear ratios of the two transmissions shows that first through fourth are basically the same. Since the power band of the two engines is different, to really take full advantage of the effect of the Paxton it would probably be necessary to experiment with the gear ratios. They were designed for the original power distribution of the stock engine. I wonder whether anyone has done this. For instance, I wonder what a Paxtonized car would do with a first gear that allows a shift to second at 6200 ( the redline with the DC blower tune) at about seventy MPH with additional gear changes that reduce the rev drop between gears. This would allow the Paxtonized Viper to stay in its sweet spot.

 

[hou99gts]

How about adding headers to the Viper? Maybe a cool air charge from the front of the car thru a fog light opening, etc?

 

[Nine Ball]

You can also look at the tune. Unless both are dialed to the same timing and AFR you are not comparing things on an even playing field. There are a lot of variables in a tune....

The added weight of the Viper doesn't help at all....

Tuning was performed by the same guy. He tunes most of the high performance cars in the Houston area, even some 7-second 200+ mph drag cars. I watched the tuning process, we kept both cars safe as far as A/F ratio and timing. I prefer having reliable fun cars, not cars that push the boundaries of kaboom-ing.

Viper is heavy indeed. In stock form, they are already about 250 lbs heavier than a Z06 is. I did lighten both vehicles up with HRE wheels and 2-piece rotors, but the blowers added weight right back to both cars.

 

[FLATOUT]

Tony the restrictor plate could really help with the mid range. Keeps full boost where you want it but the smaller pulley with restrictor should allow you to make more boost sooner, more like a PD blower.

I would talk to Doug at at ECS in Jersey a's they have done wonders with Novis with restrictors on the Vettes.

Super cheap and worth a shot.

Andy

 

[mnc2886]

Guys, I work in NG compression, so I am going to give my theory on the issue based on what I do for a living. I think the problem isn't gearing as much as it is compression ratios. For instance, his Viper is a 9.6:1 compression ratio while his Z06 is 10.5:1. He is going to create power more immediately in his vette because of that fact which gives him the jump. Because of the lower compression ratio in the viper,there is a lower volumetric efficiency until higher RPMs, which in turn prevents him from making serious power until higher RPMs.

 

[FLATOUT]

Guys, I work in NG compression, so I am going to give my theory on the issue based on what I do for a living. I think the problem isn't gearing as much as it is compression ratios. For instance, his Viper is a 9.6:1 compression ratio while his Z06 is 10.5:1. He is going to create power more immediately in his vette because of that fact which gives him the jump. Because of the lower compression ratio in the viper,there is a lower volumetric efficiency until higher RPMs, which in turn prevents him from making serious power until higher RPMs.

Or it could be the fact that positive displacement blowers create a totally different power band than centrifugals. Consider the power band and delivery of a centrifugal blower and a turbo system. PD blowers make more sooner, centrifugals are more "peaky" . Restrictor plates can improve the problem.

I think in Tony's case here, it's several smaller issues combined to cause the difference between the two cars, including things like compression mentioned above.

1. Weight
2. Trans gearing up top
3. Also at STOCK power levels the Z06 traps 4 mph higher, so the viper all things being equal would still have to make more power to run even with it.

Not sure what the viper ran stock but It probably went from 121 to 134 in trap speeds, an increase in 13 mph through the traps. His Z06 went from 125 to 138'ish, so it probably gained about the same mph a's the viper does.

Since it creates the same gains with less power it points to weight, gearing, and power band to me.

 

[mnc2886]

Or it could be the fact that positive displacement blowers create a totally different power band than centrifugals. Consider the power band and delivery of a centrifugal blower and a turbo system. PD blowers make more sooner, centrifugals are more "peaky" . Restrictor plates can improve the problem.

I think in Tony's case here, it's several smaller issues combined to cause the difference between the two cars, including things like compression mentioned above.

1. Weight
2. Trans gearing up top
3. Also at STOCK power levels the Z06 traps 4 mph higher, so the viper all things being equal would still have to make more power to run even with it.

Not sure what the viper ran stock but It probably went from 121 to 134 in trap speeds, an increase in 13 mph through the traps. His Z06 went from 125 to 138'ish, so it probably gained about the same mph a's the viper does.

Since it creates the same gains with less power it points to weight, gearing, and power band to me.

I completely agree. I guess what I was trying to say was that the lower compression ratio was making the power lag worse.

 

[FLATOUT]

I completely agree. I guess what I was trying to say was that the lower compression ratio was making the power lag worse.

I'm with ya I agree.

 

[tucker]

If Furman drove your Viper, that Vette would get smoked, even if the race wasn't at Englishtown.

1BadGTS has carried on a rather Chuck Norris like legacy.

 

[Twister]

sold the paxton on my nsx a year ago and never looked back. You are in for a looseing battle. Id put my money on a 575 rwhp ROE supercharged 1996 GTS over a paxtoned 650 rwhp 2006 srt10 any day of the week....Let alone a roots style Z06..Theirs no easy awnswer here..A rescritor plate slightly helping on the low end and a smaller pulley at 700 rwhp will get you to where your Z06 was before you added the 60 rwhp to it. Thats it..

after that you are maxed out as anything over 710 rwhp on a gen 3 stock internals is asking for it

So unless your gonna spend the coin for forged parts ect. Just forget about it and except the fact that theirs always gonna be a faster car..In this case your lucky enough to own that one as well..

Did your drag your cts-v yet?

 

[Seb]

your not going to beat the response of a twin screw blower like a opcon auto rotor/ whipple= ROE

On the shift where does rpm drop to?

Weight? not helping you at all.

Engine rpm limit? you loose alot on the shifts I bet

Easy answer.....spin your engine to 7000rpm. The less shifts you make the better off you will be. Or you can just put a sequential tranny in it and make the ratios a bit closer.