As I'm new to the Vortech SC, I'm wondering if it's normal to not be able to build boost unless throttle is at or near WOT. At 1/2 throttle or somewhat more, for example, BOV closes and boost goes to 0-1 or so but plateaus around there and even drops back to vacuum even as RPMs keep climbing.
Serp belt feels tight and doesn't squeal. BOV is a new replacement (the one that came with my kit was definitely defective) with ~7 threads showing. Closes at 4" or so of vacuum. Power seems fine, but boost only really comes on with WOT. This doesn't really make sense because, once the BOV closes, it seems to me that no matter what position the throttle plate is in, boost should just continue upwards in a linear fashion as long as you don't let off the pedal.

Are you able to continue steadily building boost at 1/2 throttle as RPMs go up--without flooring it--or does your boost seems stuck around 0-1 lb unless WOT? I posted this question in another thread about BOVs, but didn't really get a clear answer.

 

This is the latest datalogging image I have from my lastest dyno run. As you can see, "boost" did not increase until WOT. Keep in mind, this is Zeitronix data. Boost at 6000 rpm of 3.0 is closer to 7.0-8.0. I will try and go in and gather data at point where "boost" increased (i.e. rpm / boost value) then post.

 

As soon as your BOV closes the boost will build relative to your rpm . And if you dont continue to build rpm AND keep load on the motor , the boost will level off and drop off till the BOV opens again under vacuum

 

That's exactly what one would think should happen. But, even though RPMs keep going up along with speed, unless at or close to WOT, boost doesn't get up to more than 1 or 2 and then drops off. But, at WOT--no problem as long as the pedal is kept to the metal.

Now, with the Zeitronics tracing, I assume you read it from right to left. It appears that you go from no throttle to WOT. I'm curious about what happens at 1/2 or 2/3 throttle. Will boost continue to build linearly without going to WOT but just holding it at 1/2 to 2/3?

 

That's exactly what one would think should happen. But, even though RPMs keep going up along with speed, unless at or close to WOT, boost doesn't get up to more than 1 or 2 and then drops off. But, at WOT--no problem as long as the pedal is kept to the metal.

Right...mainly because the load on the motor starts to drop off .

 

Why does load drop off if you keep it at 1/2-2/3 throttle? As you accelerate load should increase because of wind and road resistance--not drop off. There's obviously something in the equation that I'm just not getting. I've got Corkie Bell's (? new) book on supercharging on order. Maybe that will explain it.

 

"booger" is right! As long as you are under load (i.e. WOT) your boost will increase. As soon as you backoff your boost will immediately decrease. Fairly easy to see with the Zeitronix, as the #'s on the LCD are constantly changing. Unless you are WOT, you will usually see #'s with minus values.

I am attaching pic while on a dyno as we are going into WOT. RPM is 2784 with 54% throttle. It is not at 100% throttle until it reaches the plateau. As a result of the altitude here in Albuquerque, I know the -6.6 boost shown is actually -1.6. If you would like to see a value at a different RPM, just yell.

 

Your RPMs stay stuck even when you go to WOT. Is this a function of the 5AT?

In a manual in, say, 4th gear at 65% throttle, RPMs should steadily increase as the speed of the vehicle increases. Assuming that the BOV closes initially: as RPMs increase, blower speed increases and, therefore, boost should increase, at least to a steady state--counterbalanced by the engine's ever increasing vacuum. Perhaps the drop off in boost and return to vacuum I'm seeing with partial throttle is caused by engine vacuum overcoming blower pressure--leading to BOV opening when vacuum hits about 4" and then a big drop off in boost. Follow me here--the engine's vacuum increases linearly with RPMs, but the blower's increasing pressure is partially blocked by the half-closed throttlw plate. So, eventually, intial boost turns to later vacuum. That's got to be the reason that boost drops off and goes negative unless the throttle is wide open.

 

Not sure I am following the "stay stuck". That white line you see is a cursor that I can move and view values at a particular rpm. While it is not shown, the time at WOT on the dyno is very short. Your in manual mode and shifting through 1st, 2nd and 3rd and dynoing in 4th. Once you reach 4th you got WOT and start recording and datalogging. That steep rise you see prior to the plateau is very short in time. The plateau is also short in time as is going from 2784 rpm to 6000 + rpm. You are also at 99%-100% throttle during that time

 

Your RPMs don't increase much when you stomp on the pedal. Why is that?

 

The conditions you are recording on the dyno and datalogging with Zeitronix are different than what you might experience at the track or on the street. You are slowly progressing to the gear that in which data is going to be recorded. I believe for the MT it is 5th, while for the AT it is in 4th. Also, to the best of my knowledge and perhaps unfortunate, you don't datalog the time that it took to get from 2784 to 6000+ rpms.

While you are on a dyno in 5th, how fast did you rpms increase?

 

I think he may be refering to the blue rpm line . With Zeitronix the rise in the line is gradual . SO it doesnt look like it goes up real fast like the TP line does

 

You are probably right Bill! The load on the dyno and the experience you might see on the street is a lot different. The TP curve and the RPM curve would be much different if I was logging while sitting in my garage and going WOT.

How are you doing with your Zeitronix? Have you gotten to the point of doing some tuning with the Zeitronix and R4? For me, awaiting delivery of PE380's and completing my other "Z" project.

 

Yes ive done some tuning , for the second time . I got the TS flash for the 550's and have totune it all over again . But I wasnt done anyway . The eitronix is working great

 

Do you think I will have to do anything with the 380's? Based on a previous post of yours and a PM hoping to adjust A/F with R4 and Zeitronix data. Currently have the "limited Flash".

 

YES....you will have to scale them back , if TS didnt flash for the 380's...I strongly suggest doing the TS flash . It makes a big difference on how the car responds . Im real close to being done on the street tune. I did 8 runs today and got the A/F at 11.5 to 11.8 . Next week comes the smaller pulley , if the weather is nice enough to tune it . Once I get the pulley on and the A/F right for it , I'll hit the dyno and make sure its right and take some timing out . I got a bunch in it now to be safe

 

Sent an e-mail to Danny at TS asking when would be a good time to return my ECU to them for reflash for the 380's. Hope they leave what they have already done alone (i.e. rev limiter, throttle and speed). I know you were having a problem with TPS showing 85% Vs 100%. Did they correct that? From your posts, it sounds like when they get done adjusting for larger injectors, what you have to do with the R4 is minimal. Did you end up setting all cells back to 10.2 nd then adjusting up or down?

 

When you send it in ...fill out the form you print out from there web site . Tell them to leave in what you want left in and tell them what to add.
My TPS is right...wasnt sure if it wasnt...dont know for sure .
I put back all the cells in the vacuum side of the map back to the stock Vortech settings...Mine was 10.2...some are 10 , 10.4 ,
I still had to tune the boost side of the map

 

Thanks for the info! I like what I have (i.e. rev limit 7200, 100% throttle and speed limiter removed), just need them to adjust for PE 380's.

When was the last time you looked at the "Split Second" site? For me it has been a while. They now have, detailed instructions that can be downloaded on "U-Tune Aftermarket Performance Tuning" for the R4 Software. I know back when you and I got started with this it was a self learning project unless you had a tuner that knew R4 like the back of his hand.

 

Hey I just looked at Superchargersonline.com They say the ..V2SC blower will spin faster than 70,000rpm's....Hmmmm...Vortech says 58,000 for are cars .