RIGHT NOW I AM HITTING AROUND 13 TO 13.5 I THINK IT IS SLIPPING I ORDER A IDLER PULLEY .
THANKS
THANKS
WHAT IS THE MAX. PSI. FOR A 2.80 PULLEY WITH NO SLIPPAGE?
- Thread starter 03BLKCOBRA
- Start date
With the 2.76 and idlers I was dead on at 15 at my last dyno session.
Typical of roots type blowers
Unfortunately, roots type blowers get less efficient at higher RPMs.
If you look at the typical supercharger fuel system setups on the top fuel dragsters (which are limited to roots type blowers), you will see that they use lean out systems that bleed of fuel and return it to the tank once the motor reaches a certain rpm (actually fuel pressure opens a return valve). The mechanical fuel pumps which run off the motor rpms increase pressure in direct relation to the rpms. As the motor speeds up so does the fuel being delivered but the blower doesn't keep up at the top end. Hince, a simple system to bleed off fuel and lean the motor back out is used.
In the top alcohol (Federal Mogul class) screw type blowers are allowed. Interestingly, they have the opposite problem. They become more efficient at higher RPMs! Thus, you have to have a way to increase fuel beyond the linear rate/rpm that the mechanical fuel pumps deliver or the motor will lean out at higher rpms. Whipple and PSI superchargers are both screw style blowers.
I love superchargers. They are consistently the most bang for the buck. Of course, with electronic fuel injection systems, precise fuel/air delivery can be maintained accross the rpm spectrum with the right programing. There is no reason, besides overall motor structural integrity, that our motors can't churn out 1000 hp plus with a good screw blower.
Unfortunately, roots type blowers get less efficient at higher RPMs.
If you look at the typical supercharger fuel system setups on the top fuel dragsters (which are limited to roots type blowers), you will see that they use lean out systems that bleed of fuel and return it to the tank once the motor reaches a certain rpm (actually fuel pressure opens a return valve). The mechanical fuel pumps which run off the motor rpms increase pressure in direct relation to the rpms. As the motor speeds up so does the fuel being delivered but the blower doesn't keep up at the top end. Hince, a simple system to bleed off fuel and lean the motor back out is used.
In the top alcohol (Federal Mogul class) screw type blowers are allowed. Interestingly, they have the opposite problem. They become more efficient at higher RPMs! Thus, you have to have a way to increase fuel beyond the linear rate/rpm that the mechanical fuel pumps deliver or the motor will lean out at higher rpms. Whipple and PSI superchargers are both screw style blowers.
I love superchargers. They are consistently the most bang for the buck. Of course, with electronic fuel injection systems, precise fuel/air delivery can be maintained accross the rpm spectrum with the right programing. There is no reason, besides overall motor structural integrity, that our motors can't churn out 1000 hp plus with a good screw blower.
thanks i hope the new pulley idler will help..
My gauge shows around 13 psi, but that is with just Ray Hilton's overlay. :shrug:
With my 2.80 I get just a tad over 13 with Ray Hiltons overlays, which I calibrated to a saleen boost guage so its pretty damn close, my next dyno session I want to have it read at the dyno as well. Some say they are making 15lb's with a 2.80 , I dont think its possible to make 15lb's with a 2.80 and offroad exhaust which is what I have!
Mine spikes 13 and holds 10.5 lbs. Inlet,php air box, catted x pipe, and a metco 100mm idler
12.5 - 13psi for me :shrug: At higher Altitude only 11.5 - 12psi.
brent mentioned about getting the dynojet stack so they could read boost while doing a dyno when i was down there sunday.with my rr 2.75 my ray hilton overlay was showing 14lbs dropping down to 12lbs at 6,500 rpms.
On a hot day, I usually see about 13-13.5 on my calibrated, modified factory gauge. On a 40 degree night, I can get 14.5-15.
Boost will drop 1-2 psi at higher rpm in both cases.
I run a homemade "JLP" dual pickup CAI with 9" K&N, BilletFlow TB, plenum, & upper idler, SFPHQ non-slip 2.80, 74" GB belt, QMP 3" exhaust with O/R X pipe, and DiabloSport Delta chip.
I feel that the "forced" cold air helps to keep the Eaton a little more efficient longer.
454/486 SAE
476/509 STD
12.02@119 w/1.91 60' on F1s
Boost will drop 1-2 psi at higher rpm in both cases.
I run a homemade "JLP" dual pickup CAI with 9" K&N, BilletFlow TB, plenum, & upper idler, SFPHQ non-slip 2.80, 74" GB belt, QMP 3" exhaust with O/R X pipe, and DiabloSport Delta chip.
I feel that the "forced" cold air helps to keep the Eaton a little more efficient longer.
454/486 SAE
476/509 STD
12.02@119 w/1.91 60' on F1s
In S. Ga. the air is so thick you can skip taking every third breath. hehe
i will re test on thrusday.
my hits 16 when you first jump on it then falls too 13 by redline. that with a 2.80 and idler.
Mine reads 14 psi and drops to 12 after 5500 rpm and that is with no belt slip 2.8 pulley with 100mm metco idler.
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