roe sc drivability

[jwbond]

I am sure I will fall in love with the extra power from a roe install, but am concerned about losing drivability. Is the car still easy to drive at low speeds or does the added low end torque make it clunky when going slow (I know, who goes slow...but I mean through a city w/ traffic lights)?

I'm all about extra power, but don't want to downgrade in other areas.

 

[viperdude118]

Can't speak personally since I don't have a supercharger....yet. However those I've spoken too say and I believe most will agree, that an added supercharger with a proper tune will improve overall driveability in all driving conditions, slow or fast. Reports of smoother idle and day to day driving is much better than stock.....

 

[jwbond]

Really? Well that pretty much seals the deal then...I have a new winter project for 07-08!

 

[Madduc]

Why wait till winter? About to finish mine up hopefully today. Today will be the Jesel's and button up a few odds&ends. So far it's only taken two weeks, and that's not working on it every available day. The instructions provided make it so easy, even a caveman could do it!

 

[jwbond]

I neglected to mention, I am half cave-man. I also don't have much time on my hands and am concerned it will take 3 weeks or so being that I will only be able to work on it here and there.

3 weeks is too long to stay away from my boy petey!



what pulley are you running? keep me posted on the outcome!

 

[JohnnyBravo]

I've had my Roe blower on the car for almost 2 years. I had the car about 90 days before I installed it. There is absolutely no change in drivability with the blower. The car starts, idles and putts around in traffic just like it did when it was bone stock.

You will definitely notice a difference in power when you stand on it, even at 1,500 rpms. It's not like a Paxton or other centrifugal blower that builds boost as the rpms rise. The Roe makes full boost immediately. In my opinion, that's what makes it so much more fun to drive. The power is instantaneous. Long gone is the need to run the car up to 6,000 rpms to make power. But if you don't put your foot in it, you would barely know it was there.

You won't be disappointed with the Roe. I've had absolutely ZERO issues with mine and I've put 6,000 miles on the car and been to the track a handful of times. Joe Donovan in St. Louis tuned the car for me around Christmas of 2005. We had a Viper dyno day here in KC in May of 2006 and the car dyno'd 610/665 off the methanol. We had a Viper dyno day last month (May 2007) and the car dyno'd 612/665. I was shocked. It dyno'd basically EXACTLY the same as it did the year before without ever touching anything. That's a testament to the reliability of the system and a good tune.

 

[X vetter]

Absolutely no disappointments with the Roe...just remember to make sure you've got it pointed in the right direction before you stand on it

 

[jwbond]

great news! sounds like the roe is exactly what im looking for. What pulley were you using for the 612/665 dyno pulls? I am looking at the 6.5 and am curious as to what power I can expect (the roe site seemed to only have 8lb pulley dynos).

 

[plumcrazy]

the NY/ct has pleanty of roe cars in it that drive on a weekly basis. i never heard one of them complain of anything to do with the roe. and they put lots of miles on them

 

[DEADEYE]

great news! sounds like the roe is exactly what im looking for. What pulley were you using for the 612/665 dyno pulls? I am looking at the 6.5 and am curious as to what power I can expect (the roe site seemed to only have 8lb pulley dynos).

Those 6xx numbers are usually had with 8 and 10 lb pullies. I think you can expext mid 500's with a 6.5.

 

[Bobpantax]

Below is a slightly edited prior post that I thought would be helpful to you. For the whole thread, go to the thread started by me entitled "Its Here!". The thread is in the SRT 10 forum.

1. No w/m on old car. Supercharger and VEC II installed and tuned by Sean Roe.

2. From zero to sixty the Roe GTS was more dramatic and very difficult to launch on street tires without losing traction. This was the result of the lower RPM /torque curve. The Paxtonized SRTC is just as fast but the power is more easily controlled. Part of this is due to the suspension mods I had done. My GTS had a stock suspension. On the high end, above 4000RPM, the Paxton is the clear thrill winner. The Paxton keeps getting stronger and stronger all the way to redline. It is one high adrenaline ride! The Roe GTS's peak torque was at 3500 RPM's with its peak HP at 5450 RPM. The peak torque for the SRTC Paxton per the dyno immediately after installation was at 5450 RPM and the peak HP kept climbing all the way to redline. The torque for the Roe was above 500 ft lbs at 1800 RPM. The torque for the Paxton is above 500 ft lbs at 3900 RPM.

3. The GTS had forged pistons. The SRTC has stock cast pistons. With the stock Paxton installation, the stock pistons are sufficient.

4. I do not know what the stock Paxton setup generates on a Gen II. My 8lb Roe GTS generated, without water/**** and already well broken in, RWHP of 546.9 and RWT of 613.72 on a dynojet dyno on a conservative tune. The Paxton SRTC numbers, also on a conservative tune, converted to dynojet numbers from Mustang dyno numbers, generated 649.2 RWHP and 602.3 RWT when the car was brand new right after installation by Woodhouse and only 19 miles on the clock. The SRTC, which is now well broken in, now feels much stronger than it did when I first got it.

5. Anyone thinking of supercharging should keep the A/F ratio safe unless they like metal fragments. They should also adjust/modify the suspension for the difference in weight caused by the supercharger and the difference in power. It really is worth it to get the car corner balanced if any spirited driving is anticipated. It reduces the probability of what I call the "ass around syndrome".

I hope the above is helpful.

Bob

 

[jwbond]

They should also adjust/modify the suspension for the difference in weight caused by the supercharger and the difference in power. It really is worth it to get the car corner balanced if any spirited driving is anticipated. It reduces the probability of what I call the "ass around syndrome".

thanks Bob, great post!

How do you go about modifying the suspension? I would assume this can't be done by anyone and can't be done without track testing. Or is there a standard rule of thumb that others have gone by?

 

[Steve 00RT/10]

JohnnyBravo states it well........here's a litte more: Almost 15,000 miles since self installed and tuned last year. 5 pounder/ no water ****. (don't want to lose the trunk room for travel...a definite consideration if you travel) I'm guessing 580+ RWHP based on our other car's dyno of 554 with basically the same set up......and also given the dyno tune from 2003 on this car was running low 10s AFR to get 554 HP. WAAY rich. I've improved on that some this past spring. Our 2000 RT/10 is quite a bit stronger than the 2001. I do have 1.7 HS roller rockers in the 2000 car and no cats.

Drivability issues: slight idle quirk, not necessarily due to the blower, although conincidentally it started 100 miles after install. Certainly not a show stopper by any means. Other than a slight whistle around 1200 RPM, you would have no idea it was on the car--until you mash the gas . Even with a stock rear end 5th and 6th gears become much more usable. I have a light flywheel in both cars, Belanger headers, 3" exhaust (different types), and a 3:45 rear end from Unitrax in the 2000. ZERO traction problems with the 3:45 gears. (but then I don't drag race and 0-60 is nothing I really ever do.....I feed the gas in...quickly...works just fine)I would do the same thing, the same way, over again. Personally I like the idea of making the big torque down low and keeping the rpms down on the engine. I've now done a couple track events (flawless performance in 4th gear) and a few autocrosses. No suspension mods. 90+% of all drivers will not need to modify their suspensions for the limited use their cars see. If your car sees a track only a time or two a year, or not at all, you'll never be good enough to out drive what the car came with from the factory. I did add a little brake upgrade to the back (Tom Hayden's 40MM caliper set up--excellent!). If money was an object, I would do the back brakes before tweaking suspension. The OEM brakes on the old Vipers were 'not good' so to speak. I figure the SC adds about 40 pounds to the front end. You can have a larger differential than that between the front and back just with your gas tank.

Go for it! You won't be disappointed. If you like, I can supply some added tips on the install from a daily journal I kept. I had never tackled anything like this before and wanted to write it all down.

Steve

 

[Bobpantax]

thanks Bob, great post!

How do you go about modifying the suspension? I would assume this can't be done by anyone and can't be done without track testing. Or is there a standard rule of thumb that others have gone by?

This data may be helpful to you. it is an explanation of "corner balancing" from Mark Jorgenson at Woodhouse Dodge. It describes the procedure that he used after he put Eibachs and Moton shocks on my new SRTC.

"When we corner balance a car we start out by driving the car for a short distance to seat in the springs and shocks, then once on the rack we loosen all the bolts slightly to insure that there is no binding and set the overall ride height front and rear and the rake. From there we put the car up on the scales and adjust the corners to get the weight at the cross corners as close to 50 -50 as we can with the drivers estimated weight in the seat. This process will change the look of the wheel well heights on each corner slightly but is necessary to balance the car. After all the balancing is done we start the alignment process insuring the settings are where we need them and the toe patterns are good front and rear through the bump curve. With all the specialty tools to do this job it is very time consuming and when done right really transforms the handling of the car."

Mark also said that done properly it takes about six hours by someone skilled in doing it.

 

[Schulmann]

Drivability ?!

I put over 20000mi on my supercharger. It drives perfectly in city and on hwy when well tuned. Pay attention to the AFR. If AFR is too lean above 16 AFR your engin will hesitate espetially between 2000rpm and 3000rpm.

I had different programs for hwy and city. On hwy I privileged the fuel consomption. I was able to get as high as 30 mi/g ( I was driving at 16.5AFR). In city I priviledge the drivability in all rpm ranges. VEC2 is like the best video game. You can tune the engin as you want. You can adjust the setting according to any preference, fuel, temperature so on. So drivability is not an issue at all from my point of view.

Then I had programs for track events and drag races. Those programs were also different. Usually during drag races you have to lean out the normal race program because of the engin's temperature.

The only issue that I noticed was when temperature changed suddenly from 90F to 30F. Sometimes I had to load a new program juste to start the engin. But for this issue you have to be deep in the North.

 

[GR8_ASP]

Just finished the Motor City Dyno Day. We had both a Roe (Gen I version) and a Paxton (Gen III version). Also several Gen II and Gen III cars for comparison. Only 1 other Gen I for comparison, and it was heavily modified.

On the graph below the top 2 curves are the Roe and Paxton. You can see below 3750 rpm the Roe has more torque/power. Beyond that the Paxton is stronger. A Gen II Roe is similar but somewhat higher torque and power, but th egeneral shapes are similar.

 

[Bobpantax]

I am sure I will fall in love with the extra power from a roe install, but am concerned about losing drivability. Is the car still easy to drive at low speeds or does the added low end torque make it clunky when going slow (I know, who goes slow...but I mean through a city w/ traffic lights)? I'm all about extra power, but don't want to downgrade in other areas.

A few things to note with the Roe.

1. The first mile or so after start up tends to be a little rough until the plugs heat up. This is normal. I do not know whether anything in the VEC III changes this behavior. My old GTS had a VEC II.

2. The car will be louder. If it is for offroad use and you modify the cats - high flow cats or no cats, the sound is almost painful unless you add some sort of low resistance extra bullet muffler and cones. Please read Sean's websit FAQ's egarding air fow requirements and cats.

3. You really have to be very, very careful you do not slip and hit the pedal too hard. The power is there at 1800 RPM. Pay attention to the surface you are on. Any sand, gravel, oil, etc. in the road is not your friend.

4. If your tires are old and hard, get rid of them even if there is alot of tread left. Old, hard, cold tires plus foot to the pedal equals spin and/or wreck. Even with new tires be sure they are heated before you play.

5. If your brakes are stock, upgrade them. The stock brakes are not enough assuming you are going to use the added power and the Roe is not just for show.

6. If you do add the Roe, take the car somewhere very safe and wide and practice. With the supercharger, the car is a very different beast. Don't believe anyone who minimizes the difference. The lowend torque produced by the Roe is fun if its effect on handling is respected. Shift points and pedal modulation have to be relearned. Have fun.

Bob

 

[GTSPOWERED]

I have had my ROE for 2 summers and no problems and today I put around 150 miles on it just driving around and not a single issue. I love the low end power.

 

[RedEnuf93]

Over 5000 miles with my Roe, no issues with blower drivability. It is actually better, car pulls GREAT and is an absolute hoot to drive on curvy roads. This was the reason I went with ROE, not Paxton or TT. With Paxton or TT you can make a ton of more HP. I thought that around 550-600HP from stock GEN1 motor with Roe is enough for me.

I did however change to a 17lbs chrome moly flywheel, that WILL cause the car to **** quite a bit at lower RPM's (500-900). It does not bother me, but I can see how it would bother someone else...

 

[GR8_ASP]

I disgree completely with the reasoning. A Paxton, or similar centrifugal SC, is easier on the drivetrain for any given peak HP as the peak torque will be lower. Also, as a Paxton measures actual engine inlet air temp (SC/intercooler outlet) the computer keeps the a/f correct regardless of the environment. Also the addition of a intercooler keeps the inlet temps lower reducing the potential for detonation. I have also found the throttle response to be near linear and perfect for the track. You may have less fun factor (due to torque peak low on Roe) but more cewrtainty about approaching the tractive limit just by throttle position.

Note I have 2 1/2 years and 14,000 miles on mine.

My $0.02

 

[jwbond]

thanks for the input gr8_asp, always good to hear contrasting opinions before a big purchase. However, I think you further convinced me, that the roe is the choice for ME. Fun factor is what I am looking for, not better track times. (forget torque curves, I want a toque line on the dyno w/ max power down low baby!)

I always love the fact that I should be able to do the install, no drilling, and a much cheaper solution.

 

[plumcrazy]

sounds like thats your answer then. enjoy the roe !

 

[Purdue_Boiler_Viper]

I've had my Roe on for about 2 months. I also have high flow cats, RT cat back, Jesel rockers, and a Hurst shifter along with the standard smooth tubes and air filters. Suspension is stock, tires are 7 years old. I stuck with the stock spark plugs, as Roe recommends them unless you are doing a lot of WOT.

My 01 drives pretty much the same as before the install, except when I really jump on the gas. Then the fun begins. You don't need suspension, drivetrain, or brake upgrades unless you're tracking your car, or drive on the street like you're tracking your car. You control the torque easily with the gas pedal.

You won't even know that it is there, until you jump on the gas or open the hood to show others. This is the biggest difference. You will have to show the guy next to you at the gas station. Be aware that he will drool.

As far as install goes, not too bad. With help from us guys here, you can get it done. I did it by myself, with only a little help from the wife. It took me about 3 weekends. The crankshaft pinning is the hardest part. You might want to consider changing the power steering pully and bracket while you are at it.

 

[viprvenm]

I've got about 7k miles on mine and have not had any problems with the S/C itself.
I have blown two header gaskets and a head gasket about one year ago... and now have an exhaust leak, but it is a small price to pay for HIGH HP!!!

Jason

 

[jwbond]

I've got about 7k miles on mine and have not had any problems with the S/C itself.
I have blown two header gaskets and a head gasket about one year ago... and now have an exhaust leak, but it is a small price to pay for HIGH HP!!!

Jason

you are making some crazy power, but I think I would prefer reliability over crazy numbers. What size pulley are you running?

 

[Steve 00RT/10]

I disgree completely with the reasoning. A Paxton, or similar centrifugal SC, is easier on the drivetrain for any given peak HP as the peak torque will be lower. Also, as a Paxton measures actual engine inlet air temp (SC/intercooler outlet) the computer keeps the a/f correct regardless of the environment. Also the addition of a intercooler keeps the inlet temps lower reducing the potential for detonation. I have also found the throttle response to be near linear and perfect for the track. You may have less fun factor (due to torque peak low on Roe) but more cewrtainty about approaching the tractive limit just by throttle position.

Note I have 2 1/2 years and 14,000 miles on mine.

My $0.02

Ron,

As long as the tires remain the shear pin, there should be no drive line issues at all. You are the bearer of that knowledgew to me........and I adhere to it by going through a set of rears per summer. Of course I did the same for several yrs. before adding the Roe

Isn't it also true that the stock Viper valve train springs don't care for continued high RPMS? ......which is where the centrifugal blowers shine-----at the very top. I always try to shift between 5000....5500 RPM.

Hard to argue the intake temp/intercooler thing--it's a better set up, although the new VEC 3 feature allows for percent fuel add/subtract in a linear fashion and seems to be working quite well for me. If my logged AFR is about where I want it as the temp rises or falls through the airbox, then doesn't the actual supercharged air becomes a relative number to the IAT air box temp and my percent fuel add/subtract?. I also think sticking with the basic 5 pounder makes the Roe equation much less complicated, easier to tune, and more troublefree. I wish I could have an intercooler, but can't to date.

I'm also not sure there is a Paxton DIY kit for novices out there for a GEN II car. At least not 1.5 yrs. ago. There were a couple horror stories on this forum about the same. The ROE is definitely able to be installed by regular novices--like me. I've logged 15,000 miles in 14 months with no blower related issues so far.

At the track, my 4th gear(with 3:45 gears) was pulling equal to, or slightly harder than, the stock Viper 3rd gears, allowing me to run all day between 2000-4500 RPM. With 3:45s, my 3rd gear is done at 95 MPH. Lots easier just to leave it in 4th. I have had zero tractive limit problems with my set up--other than when I wanted to.....like today at the autocross. I started all but the first run in 2nd gear...smoking the tires for a little show all the way to the first corner one time when the 'crowd' wanted to see a little extra action on my last run. I had to modulate the pedal in 2nd gear to keep from hitting the rev limiter.

Steve

 

[plumcrazy]

the paxton kit is not that hard to install. if i could install a DLM paxton...anyone can...

 

[TexasPettey]

I had my '95 for 8 years before moving up to a ROE kit. I've had my ROE kit on my Gen1 for about 3 months at 2K miles. It made 600RWHP-600RWTQ with heads, cam, exhaust, and a 6.5lb pulley.

The car is much different. It was a beast out of the factory. Now, it is an ancient titan spewing venomous fire with every breath. Damn I love it! With so much power at the low end, I launch at a very low RPM to minimize wheel spin. It takes a bit of throttle control, especially under the changing conditions of the street. I don't go full throttle on the street, unless I pointed in a straight line with good conditions.

One other thing I love about the kit is the way it looks. At every car show I go to, as many folks oggle over the engine bay as the exterior.

The only issue I had with drivability is that at first I had some 'surging' at part throttle around 1500RPM. I had my tuner adjust the waste gate profile, and it went away.

 

[GR8_ASP]

Hi Steve. You are correct that I said the tire is the "fuse or shear pin" in the system. But that is just one thing.

In essence the peak torque the driveline will see is the tire resistance plus the torque to accelerate the driveline and wheels. So in first gear the engine torque will not result in a large increase in driveline torque, given that a stock car also spins the tires. But that is only the maximum case for the differential, propshaft and halfshafts. The transmission has a different torque handling capacity in each gear, and gears above 1 will indeed observe full or near full engine torque. The clutch will also see full engine torque. So the trans and clutch are directly impacted by the increase in peak torque. and all components have an increase in duty cycle. that is the amount of time that they will see tire adhesion level of torque or higher.

So to say a peak torque higher will not cause damage is not exactly true. Though the most susceptible portions (differential and halfshafts) are limited to tire adhesion torque. But of course change the tires to stickier rubber and the equation changes.


Now back to that old statement that Paxtons shine at high engine speeds. Not really true. Look at my dyno traces. You will see torque is quite stable from 3000 to 6000 rpm. The feel at 3000 is pretty closeto that at 6000, and 3500 is near equal. Peak vehicle performance does require the use of the top end of the rpm band (especially in 3rd gear and higher). But that is the same as all Gen III's. Cyclic fatigue is indeed increased but other aspects are not affected as they are more affected by peak cylinder pressures than engine speed. Piston, conn rod, crankshaft, and even the head gasket are all more affected by the cylinder pressure, for which the Roe is decidely higher for the same peak power. Bearings are affected by both speed and power and which one is more damaging is not clear.

So that is my $0.02 for Sunday night.