Question on my Super Charger

[Blue Streak]

I am very happy with my DLM SC but Ive got a question on a SC Viper. Need some enlightenment. There's a lot I don't know about a SC. I am learning a lot and Viper alley members have been very helpful.

The SC is to come in some where around , give or take, 3400 rpm. I was expecting the SC to at least come in at 3/4 throttle but it only comes in at heavy WOT. In other words you have to stomp it hard but yet the Viper is running much stronger in all gears after the SC install.

I am mentioning this considering boost figures. In first gear under wot about the best I can do is 3-4 lbs of boost and this is probably ok. Second gear about 5-6 lbs and about the same in other gears. Maybe 7 in third gear under wot. Believe me the boost gauge and connections are ok .

These boost figures are without hitting the rev limiter. Now if I knock the tar out of the rev limiter then I can get the higher boost. I hate to hit that rev limiter with the SC - scares the you know what out of me and at my age you don't want this to happen -things can get a little messy. Now in other words the high boost numbers are so close to the rev limiter rpm that I cant stay out of it.

I do have a light weight fly wheel and 3.55 gear. The SC computer system is split second. The exhaust is DLM with 2 hf cats. Sounds mean.

I could be wrong, but with the 3.55 gear and lw fly wheel the rpm winds up very very quick and this could be the reason I am experiencing this situation. But WOW does this Viper respond quickly when you hit the gas pedal-and I like that.

Don't get me wrong -I am very happy with my Viper and the SC. The Viper runs like a bat out of you know where. Just some questions that some of you may help me with.

Another thing I will make comments about on this thread is the Hoosier 19" A6's on the rear. Unbelievable how the Viper hooks up with these tires. Absolutely no fish tailing in any gear. Under WOT the Viper hooks up and goes straight as a arrow.

[Richie-SRT10]

Gene I am interested in more info about the Hoosiers.

I have the stock gears and can hit max boost in every gear. If you are not wide open after 4,000 rpms I know you can not hit max boost. I like to boost normally between 5 & 10 lbs and have learned to control it. I do not know if I ever was able to make 15 lbs under 4500. Next time I drive I will do some checking for you.

Now about the tires...

[Blue Streak]

Thanks Rick-I think I have to learn how to control it. But again the gears and fly wheel are probably the reason for this condition.

Rick the tires are absolutely amazing. Its like driving a different Viper. A few drawbacks for the street -tread life and driving on wet roads and being careful what you run over. I would say normal driving will get you 6000 miles but spirited driving 4000. I got caught in the rain a few times and with very careful driving everything was ok.

A must is the 3m in strategic places. The tires have such a soft compound that they pic up every little pebble and could sand blast under neath the rear fenders. Of course I got that a little with regular tires but much more with Hoosiers.

For normal driving or for a little trip I put in about 30lbs but for best grip 26-27 lbs. Warms up very quick-just a little spin in my drive way and their ready to go. Very little warm up is needed.

Rick- in 1st gear under wot just a little spin then it hooks up and goes straight without fish tailing. I cant make it fish tail in 2-4 gear. It just hooks up and flies. I don't know how the tires would perform with all the power you have but I can't imagine running regular tires with the HP power of your Viper.

I may consider the R6 the next time around. Hoosier wants me to try them. Harder compound so they will need more warm up. But you could get lot more miles out of them. I hesitate because the A6 is absolutely a real performer.

I don't know what I will do if I have a blow out with no spare. I carry the green stuff kit just in case but that wont help if I slice a tire or blow one out. I guess the best of two worlds is to have a extra set of rims and put my 19" Pirellis on when I go on a trip-but I don't go on long trips anyway.

Taking in all the pros and cons for my situation I believe the A6 is the best. Rick you wont believe how your Viper will perform with these tires. Get you a pair and try them. You wont go back. Think about it Rick no fish tailing.

[The Former PFR]

Unless Doug has set the bypass valve for boost by gear, you should be able to make full boost in every gear-- its not a turbo, its a centrifugal blower which given the same RPM level and throttle position, should make just about the same boost

P.S.-- make sure your belt is tight too!!

[plumcrazy]

check the belt first.

and dont you have to be WOT and a bit higher in the rpm's to see full boost ?

[Blue Streak]

Ive checked the belt quite a bit. Seems to be tight. Yes I would think one would need to be wot in higher rpm.

Those of you who are running SC under wot how much rpm does it take to hit max boost?

Maybe at times I am not getting in to it hard enough but when I do get into it hard the max boost is so close to the limiter that I cannot keep from hitting it. I have a shift change light set at 5800 rpm and by the time the gear is changed rpm is higher- max boost under wot will not be there at 5800-I have to go above this a few hundred or more, especially in first gear, then I hit limiter. Now this could be normal and I may need to power shift better or as mentioned above learn to control it. But I still think the 3.55 and the fly wheel is in the picture.

Talking about all this-makes me want to go out on a little hunting trip. I love my Viper-My wife first then my Viper - Heck she is in Hondruas on a mission trip so I may ,till she gets back ,reverse this.

[redlineviper]

It sounds like you are getting a little belt slippage. There are two causes for belt slippage on a belt driven supercharger. One is the resistance to movement because of the force on the turbine in the compressor and the other which is usually only noticed in first gear like in your case is that the engine revs up quicker than the belt can effectively spin the compressor up to speed. In second and third etc your engine speed increases slower and slower which then makes the belts only duty to fight against the compressor. If you were to slowly rev your engine to max boost (6000 rpm) or so in first gear then floor the throttle you should see the same boost level achieved in third gear because the compressor is already turning at max speed. I would not recommend doing what I just described as it puts your bypass valve, throttle body, and engine under undue stress. Rather just trying to explain what is likely to be causing less boost than desired.