^ however they'll require retuning and I'm unsure as how it'll run out of boost.

also for those of you who don't know the 2.87 on my revup will make only 8-9lbs or so of boost so that's similar to a 3.12 on a nonrevup.

my questions were based upon that: 8-9lbs, need new injectors or not?

 

I am currently runing between 9-10 lbs boost consistent on the 3.12 pulley @ 5800 rpm. Seems like I need more power man, **** is addictive.

 

I have a few questions.

What causes more stress on the blower, a larger cog pulley or a smaller serp pulley?

Also, how are ppl seeing 14-17psi when they are only on the 2.87 pulley? Isn't the pulley acting like a wastegate for a turbo set? IE. If your wastegate spring is 9psi then u will only see 9psi no matter what size of turbo u add on so how is it possible to see more psi when the 2.87 is rated for 12-13psi only?

 

all depends on the motor and how restrictive it all is. boost is just a measure of backpressure. if your motor runs way hot, you'll have more psi (gas law, same reason you heat a NO2 tank before runs)

you get more mechanical advantage with smaller cogs.

and where has vortech every said that the 2.87 is 12 psi? that has just been forum hearsay.

 

Vortech site says it's 1-2 psi between each pulley so not sure how u are seeing 17 psi with the 2.87 and no belt slippage at that boost level unless u altered the cog setup or u running stock headers, cats and exhaust.

 

I dunno, but here's the graph from the log. As you can see, no belt slip. Sharif was quite happy with how perfectly linear the boost was on his dyno. I have plenty of other 16.5+'s as well. Doesnt really matter. I;d rather make 520 at 12.5 psi than 460 at 15psi

 

I want to make 14-16psi but from calculating the impeller speed with the 2.62 pulley at 7000 rpm ill be at 63XXX and the t trim is rated max at 55000. Is this still safe?

 

i guess in the end it doesnt matter, as there's no warranty in the T-trims anyhow.

i'd do it in a second if my built motor was in. its got the HD gear case and seals.

http://www.vortechsuperchargers.com/product.php?p=4
Warranty Information

No Warranty
No warranty on race/heavy-duty superchargers.

 

So, your making 17PSI@6300RPM on a Stock Block?

 

Since we all asking questions I might as well ask 1 myslef.
I have a non revup with the 3.12 pulley making 374.3 @ 10 psi. The only upgrades I have is the 2.5 test pipes and 2.5 exhaust. As we know we all want more power.

Question. If I upgrade my cog to a 34/28 teeth and/ or 2.87 pulley. What kind of gains could I see? Take in mine I will have 1 hell of a tuners so over spinning the SC will not come in to question.)
AND What other upgrades I can do without either the cog and pulley to achive 400rwhp?Thanks

 

You need to be concerned with overspeed of the blower with combining the 34T cog and 2.87 pulley...With a shift point of 6600 rpm this combo will overspin the blowers rated rpm by about 6k rpm..With the 2.87 and 32T cog pulley the overspedd is about 2.5k rpm...

 

Thanks for the info. I see you have the 3.12 and the 34/28. What is your whp?

My car is dyno to 6500 rpm and the rev limiter it set to 7k. If I do the change ill have to lower rev limiter to provent over spinning. I was asking what was my gains and other ways of gaining power.

If I change the cog and jackshift I'll have to tune lower then 6k rpm. I'll have to do resreach and see what kind of area under the curve it will make. Furthermore, to see if that setup can make a safe tune.

 

Go with the 2.87 32/28 You'll be glade you did....

You will gain 15 to 25 whp.

I have this set-up and rev to 7100rpm
I had this set-up and reved to 6600rpm for 35,000 miles.

Do not lower your rev limiter...

All Serp Belts slip by Design, you can have "Limited slip", but not "No slip" Serp Belts.

 

Thanks for the info. So 34/28 and the 2.87 is a bad combo? I know I'll get gains with just replacing the jackshift, but I want to get the most out of my v2 without over spinning.

 

Not saying it's a bad combo, I might do it......

There are a couple of guys that did a 2.62 with no problems

Static calc's, no slip
2.87 32/28 6600rpm blower 54,554 rpm
2.87 34/28 6600rpm blower 57,964 rpm
2.62 32/28 6600rpm blower 59,760 rpm

the 2.62 needs a small relief cut in the back side to clear the jackshaft housing.

 

The 34/28 2.87 pulley with the GTM pulley kit looks like my choice. I'll have to lower the rpm to keep from over spinning but at the same time I'll get more low end power.
I'll talk to my tuner and see if it will be healthy for my v2. Thanks for the help.

 

My setup 2.87 32/28 7100rpm blower 58,687rpm static, is more that what you will do @ 6600rpm.

By lowering your rev limiter, you make it very hard to stay off the limiter.

@7100 the car is much more of a joy to drive.

the gtm pulley kit is not a cure all for belt slip, you'll do best using my belt modifcation also. do a seach for TimRod1011 Belt Slip correction, in 2004

 

you wont gain any more low end power. Chef-j just posted his 3.12 to 2.87 pulley dyno. they are basicllly the same til ~4000 rpms. Thats the same thing i saw and the same as a couple other pulley upgrade dynos.

with such a big cog combo and small pulley, you lowered rpm window will not be very fun like Oldman said.

Centrifugal SC's have a finite power limit. you can either peak out soon with a low revving car by using a big cog combo, or peak out later with a hi rev car by using a smaller cog combo.

our cars rev to over 7k, so it doesnt make much sense to get that early max power and lose out on 5-800 rpms.

If you want to make mpre power and not just move your powerband, you NEED a BIGGER blower! Its that simple!

 

I see your point. I'll look into timrod for more info. My car revs to 7k already my power drops off at 6.5k. I thought the quicker boost comes the quicker your car becomes. Right?
As far as more enjoyable to drive. You mean it is not fun if your always in boost? Sorry for sounding like a noob just tryin to get the full concept.

 

I see thanks you answered my question.