Vboost or no Vboost

Forgot I made this video. With the vboost disconnected you can see the idle changes from having the butterfly valve left open. I didnt ride it like this, but I would assume that it would be soggy.

Hence the reason why you see the vboost tuner kits that let you open your vboost sooner, make the bike slower. The optimal place is right at the factory setting.

https://www.youtube.com/watch?v=SZ3J7MIa7vc

The only time I could see having the V-boost open earlier as an advantage would be if you went with a larger displacement engine, and needed more air earlier in the RPM range. I agree with you that the stock RPM setting is best

Mine is locked open all the time except when i sync the carbs.
Just depends on how you tune it as to how it runs.

blaxmax said:

Mine is locked open all the time except when i sync the carbs.
Just depends on how you tune it as to how it runs.

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Same here, I got am Edelbrock sync gauge for Christmas last year that works well with the V-boost open or closed.
Steve

There is absolutely NO doubt that my bike is more punchy/responsive at 4000RPM+ with the v-boost open than closed. People will argue both ways and give charts and numbers and such. The fact is that numbers do lie! how many times have you heard someone say, "Well on paper", that one should have been, better, faster, stronger etc... and then scratch there head trying to figure out what happened and why? Real life is different than on paper, and each bike may be a bit different from another. Maybe The stock setting is best on some bikes or set ups and not on others. Even where you live can change how your bike runs, Living in Denver or Miami is a huge difference in carb settings and I would guess also when it would be best for the boost. You are already getting much more air at sea level than at altitude, maybe at 5 or 6 thousand feet it would be better for it to open sooner? I don't know for sure, but I do know I like mine open earlier but admit that mine doesn't idle well with it open all the time, I've tried.

Matt

sdt354 said:

Same here, I got am Edelbrock sync gauge for Christmas last year that works well with the V-boost open or closed.
Steve

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I had a chat with dannymax and he suggested syncing with the vboost closed.
I have done it multiple ways and it does get a different response when synced open or closed.
As far as making it slower i suggest you try riding it first-
I have had quite a difference in 1/4 mile times.
Running 2 carbs per cylinder vs 1 carb with factory boost set at "kicking in" does not compare. It is how you tune it. Mine idles just the way i want it to and pulls perfect from 0 to top end. Take a listen -- it sounds like a freight train!!

https://www.youtube.com/watch?v=AvwUh1A6Jbw

With it open you do get more bottom end torque but with the stock servo set as is the bike will 1/4 mile better on most bike's with stock engine bore and cam's. And that's all i'm gonna say on that. LOL.

VMax-Mike said:

With it open you do get more bottom end torque but with the stock servo set as is the bike will 1/4 mile better on most bike's with stock engine bore and cam's. And that's all i'm gonna say on that. LOL.

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I was labeled the "FORREST" of this forum- i beg your pardon!!:rofl_200:

blaxmax said:

I had a chat with dannymax and he suggested syncing with the vboost closed.
I have done it multiple ways and it does get a different response when synced open or closed.
As far making it slower i suggest you try riding it first-
I have had quite a difference in 1/4 mile times.
Running 2 carbs per cylinder vs 1 carb with factory boost set at "kicking in" does not compare. It is how you tune it. Mine idles just the way i want it to and pulls perfect from 0 to top end. Take a listen -- it sounds like a freight train!!

https://www.youtube.com/watch?v=AvwUh1A6Jbw

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That is one nice Max you got there Blaxmax! Very clean, looks good and you're right, sounds nice too. I would think that if you were going to run with it open that it would be better to have it synched that way? What's the point of synching it closed, and then opening it which then changes it? I think you've got me thinking of trying it open again and spending more time tuning.

Matt

Hellboy said:

That is one nice Max you got there Blaxmax! Very clean, looks good and you're right, sounds nice too. I would think that if you were going to run with it open that it would be better to have it synched that way? What's the point of synching it closed, and then opening it which then changes it? I think you've got me thinking of trying it open again and spending more time tuning.

Matt

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Matt, first thank you for the compliment, i have worked really hard to get it this way and have have it 6 months now. Don't get me wrong as i thought in the beginning the same as you are thinking and i was quoting dannymax. I have quite a few ways of doing the syncing. Even use a lazer thermometer on each exhaust sometimes. I usually slot degree my own cams and certainly tune my own carbs. I use a carbtune to set my a/f mixture. Always index my plugs and have a cops setup that cannot be beat.
There is no doubt you can make it run better than just letting the vboost kick in when it is "supposed" to. That is what mechanics are all about.
If you take a look at my gallery you can see that i have been around the block a few times or rather down the strip- started when i was 16 years old.
By the way this is the 161st vmax built and had 10,000 miles on it when i got it.

Sounds like you are a fair bit more able than I am. I've rebuilt my own carbs and use a carbtune as well but I am certainly no mechanic. Mine is running very well and I am happy with the V-boost coming in a 3000-4000Rpm so I might just leave it as is. I'm off to change the oil now.

matt

I have a toggle switch on mine that when you first turn the key and the servo cycles open you can flip the switch and kill the power to the servo and stick the butterfly's open, gives you the choice of boost or no boost, I've ridden it around both ways doesn't seem to make a noticeable difference on the road haven't tried at the strip, the idle does sound different, sounds lopey like a cammed out 350 chevy has a cool factor when you pull into the parking lot, maybe that would be an option for you I'm sure there's a thread on here on how to do it, mine came that way

I still have my boost at stock setting but you don't feel it much with the way I have it set up with the stage 7 it's really a smooth transition.

In the drag strip real world testing, there is no difference in power. Because your above the point of the vboost opening 98% time. Your only out of the vboost at launch, which your at 4200 rpm at launch ( at least you should be ). So the actual power difference is nothing.

Basically what your doing is letting two carbs become one and over carb the motor at low rpm.

Running no vboost setup on a stock bike with no aftermarket mods will decrease performance down low in around town city driving.

If the factory found that vboost was beneficial at lower rpm's then would have lowered the opening point.

Adding aftermarket components to the mix then changes things and having it open all the time can be benecifical. But in my personal testing on several bikes, it made no difference other than sound cool and needing to be tuned differently to run better.

My first Vmax I didn't touch the Vboost, but on the next 5 I tried them all in various states and even though I had stage 7 carbs and Dale Walker exhaust on my fastest bike ( 10.80's ) I found it more beneficial to run it with the Vboost operational at the factory setting.

The idea is that the volumetric efficiency and valve timing at rpm levels set at the factory, the factory found the setting that they can achieve proper atomization and function without overwhelming the proper function of the carb. If you open the v boost too soon without properly supporting the change in cv function of the needle position you'll throw it out of whack.

I am sure Dannymax might be able to explain it better than I can since he is a carb guru. Sean Morely if I recall correctly pretty much says the same thing, stock seems best.

There was a post going a few years ago. Many notable members commenting on the idea there. FYI.

http://www.vmaxforum.net/showthread.php?t=23503

The consensus is it feels faster, but reality and dyno shows its not. Obviously everyones bike is different. I ve tested it enough on my past bikes to not bother with it. If you want to run without vboost, go flat slides!

Hellboy said:

Sounds like you are a fair bit more able than I am. I've rebuilt my own carbs and use a carbtune as well but I am certainly no mechanic. Mine is running very well and I am happy with the V-boost coming in a 3000-4000Rpm so I might just leave it as is. I'm off to change the oil now.

matt

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Don't forget if you are changing the filter also the 2 tabs on the cover go at the top.

scuff said:

I have a toggle switch on mine that when you first turn the key and the servo cycles open you can flip the switch and kill the power to the servo and stick the butterfly's open, gives you the choice of boost or no boost, I've ridden it around both ways doesn't seem to make a noticeable difference on the road haven't tried at the strip, the idle does sound different, sounds lopey like a cammed out 350 chevy has a cool factor when you pull into the parking lot, maybe that would be an option for you I'm sure there's a thread on here on how to do it, mine came that way

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This is where a problem arises-If you unplug the servo as customs does on his video
you cannot be sure where the venturi stops. It could and probably will not be open all the way. With the carbs off i did this and then reach down and opened it up directly across the port- that showed me that it did not open to it's fullest.You are assuming it is unless you have the carbs off and then it could still be off a bit.
If you are going to run it full open all the time the ultimate would be to take the venturi's out all together as they are causing some restriction to the port. Of course modifications would have to be done for that. I did mine with a 1988 model manifold because it was 1 mm larger than the '85. I do not have to worry about where the venturi stopped when unplugged and i have absolutely no restriction.
Anyone that says it does not help or provides a quicker ET at the track is doing something wrong.
Why do you think a tunnel ram with dual quads was invented?
Fact is factories are limited-that's where modification and creativity come in.

Blax the reason you won see any increase is because it's wide open after first gear.

I was consistent enough bracket racing on my vmax that it showed no difference at the track at all. That may change between other bikes and other riders, but none of my Other vmax's made any dIfference.

Now if you clutch or short shift below 9000 rpm then you might see some gains, because your already slowing yourself down. The servos slow to fully open, but solid enough after second gear that it won't close.

This all actual personal experience and not hear say info.

Others will chime in as well I am sure.

All i know is if you trick it to stay open I can pull the tire up in 2nd gear essayer. So that tell's me i have a little more bottom torque. Or maybe at the rpm cam range in 2nd gear at that speed the torque has a better sweet spot to make it essayer And when it was open running the 1/4 mile on it did not go any faster. My fastest time's was with it closed and rpm at 4000 at launch I'm talking about a piped and dyno tuned stage seven bike. When i pulled 2nd gear wheelie's I would twist the throttle back and forth at about 40 45 mph just before the road had a sweet wheelie spot in it and than when it felt right i cracked the throttle wide open pulled up on the bars a little and up it would go. It was all about timing speed and rpm on the sweet spot of the road. And with the v-boost open all the time the sweet spot was better. Look what i can do Scuff. And Thank you so much for this great video Chad.................vmax-mike unk:


https://www.youtube.com/watch?v=NFQjElgP744

This all actual personal experience and not hear say info.
I didnt ride it like this, but I would assume that it would be soggy.:ummm:

There must be a reason i am so successful at drag racing :rofl_200:

Soggy from keeping it open? Not sure what you are referencing there?