Hey guys,

I did a search but terms like boost, vortech bring up hundreds of pages. the search needs to have an "all words" function..

anyhow....

so when building boost on a blower (assuming its installed correctly, tight belts etc) , is that solely dependent on a the cog and pulley sizes? In other words, if everything is tight and you are only pulling say 5 psi (on a 6 psi pulley), would a better tune (fuel, timing etc) allow you to pull more boost than that?

 

NO!

supercharges are a unit that create boost based on a ratio of turns (RPM) vs the fin design of the unit itself. The only way to effective create more boost (without swapping out head units) is to change the size of the pulley to effectively change that ratio.

 

BUT wastegates can be used to effectively reduce boost so you can use a 9psi pulley for faster response but effective allow the wastegate to dump anything over lets say 7psi to keep your car safe.

 

Your breathing mods may affect the amount of boost that you run. Extremely high flowing exhaust will probably drop your boost a tad, like Hexxum's problem he had.

 

ahh, thanks! so if a person has test pipes, their absolute boost might be lower but their total HP might be higher?

also, after looking at a few dynos it appears you have to really have to be on the gas and revs to start seeing higher boost (like above 6psi) even with a 2.87 pulley.

i guess my biggest challenge with my Vortech will be starting to shift at higher then 4k rpms

 

Exactly. I was hitting almost 11 psi on the 2.87 pulley with the HKS exhaust (2.25 inch piping) as my only breather mod. I dynoed at 384whp. Then I switched to the GReddy Evo TT exhaust (2.75 inch piping), added a 5/16 inch MD plenum spacer, Fast Intentions FHC's and the Aquamist water/meth kit. My overall whp increased but I wasn't able to boost past 7psi. I knew I would lose some boost but I didn't think I would lose this much. It seems the piping of the GReddy exhaust was just too big. I switched it out to the Fast Intentions Intimidator exhaust and I regained some of that boost. I still have to go back to GTM to see what I dyno at. 400-410whp is anticipated on a conservative tune.

 

good deal Hexxum. My setup is close to yours so I will know what to expect.

Thanks!

 

Isn't that is what you want? You want the highest whp you can get on the lowest boost possible?

 

Of course but don't you think that an almost 4psi drop is too much?? I would think maybe 1.5-2psi at the most.

 

Its all about finding a happy medium. There comes a point when too much flow actually starts to sacrifice power also. You still need boost to be withheld in the cylinders in order to make power, while being efficient with extra flow at the same time. When there is too much flow, boost pressure is wasted and optimal power is not acheived. But for the most part, less boost and more power is of course better .

 

I may have to try this.......

wastegate with 7.5 psi springs
boost controller (to hold up to 10psi)
2.87 pulley to build pressure faster

Tune to hit 10 psi max map but also have a 7.5psi map. Use the wastegate to limit the peak psi, but if used in conjunction with teh 2.87 pulley ill build boost faster.........

 

im boosting 10 psi on a 3.13 pully but at 7200 rpm, but i tone it down to 9

you cant increase boost by tuning. also the back pressure plays a big role.

 

I agree. I think I have found a happy medium with the FI Intimidator exhaust. My boost is up to about 8-8.5psi now. When I take it in to have it put on the dyno, I'm just gonna have Sam check everything real quick to make sure that there are no leaks anywhere. They did check before and I also have checked. But booger brought up a good point to me, sometimes the leak happens only when you are in boost so you may not necessarily be able to detect it if the car is just idling or in vacuum. We'll see though. The car feels strong and is running great right now.

 

Um, holy crap!... shifting at 4k rpms could be s HUGE problem! Get on it and drive it like a b!tch you picked up at a local pub for a one night stand!!

 

But in Hex case, power wasn't comprimise...... what is the normal WHP on a 2.87 pulley? If he's on par with that power and the tune is conservative then I would welcome the drop. Heck if I can make 400whp on my 8psi then I'll be jumping for joy!!! Do sentry has the 2.87 pulley or T-trim?

Hex,
with a smaller exhaust were you able to boost higher and make more power?

 

I use the 2.87 with stock blower
I just have a bunch of other things done

 

If I had made 400whp at 8psi, I would have been fine with that. But my boost never got passed 7psi and I never got to 400whp. Sam checked for leaks and belt slippage and everything looked good. I have also checked a couple of times for my own satisfaction, and I can't detect a leak anywhere. So he suggested that maybe my exhaust was just too big and it made complete sense. I switched to the FI Intimidator exhaust and I instantly saw my boost go to between 8-8.5psi. I don't know what kind of power I am putting down now cuz I haven't been back to GTM to dyno my G. But as soon as I get a chance, I will do so. I'm pretty confident that this will push me over the 400whp mark.

 

A 2.87 pulley on a revup kit is basically equivalent to a 3.12 pulley on a nonrevup kit. About 9.5psi expected at redline.

 

if you want to increase boost on a rev-up kit the best thing to do is configure it to the non rev up spec's such as i did. 32 j/s cog, 28 s/c cog and 2.87 serp pulley. at 6600 rpm i am making 11lbs of boost, at 7100 i am making 13 lbs of boost. once i get my s/c back from vortech with the Si trim upgrade i will then have to do some testing to see how it affected my boost curve and max boost( i will be the first with the Si trim upgrade). ultimately if i run a 43 j/s cog, 28 s/c cog, 2.87 pulley i should be making some high boost numbers ( to much for stock block).so if i decide to cog the s/c this way the waste gate idea may be benificial to me to maintain boost at 11 to 12 peak(with the stock block). and in turn i will be making decent boost low in the rpm range. right now i am making 5lbs at 4000rpm, this could turn out to be a good thing for us vortech guys.i will be willing to do some R&D on my setup to see the negative and positive aspects of running a wastegate setup. seeing my z is not my DD i will have time to play around with this idea.

 

JET MECH-Any word on when you will be getting your Vortech back??