blower O-D

I have a littlefield HH delta bottom billet rotor fully stripped less teflon rotor lobe plugs. In you're opinion at what overdrive would be the max before it makes more heat than good air. I am running 30 psi at 40 over I am thinking I am almost there. thanks Craig

 

Craig,I've heard in the high 30's the effeciency falls way off.

 

Why do the fuel car guys run 50 % ??????????????

 

fuel guys

the fuel guys want the intake manifold heat !!!!! it makes it burn better..

 

I always keep my eyes open for the heat thing, but,,,
I run as close to 14,000 rotor speed as I can, it's worked for me on 8's/14's, LF's and SSI's.
We ran 68 over until the rules people decided we were too powerful so they cut us back to 50 then they cut us back to 43. Next year I'm thinking we will have to spin them backawards to suck the air out of the motor
What's your experience?

 

I've been running pump limited classes for years, so we usually don't get over 29-35%. I know we have no heat issues at 35%.

SSI 671, 464 AJPE, 7 gallon pump

 

I understand what is trying to be explained here but way back in the early nineties before psi screw blower all alcohol cars ran in the 56% overdrive. Nowdays that is gone but my biggest cuestion is how many degrees is considered the norm and the max before power falls off?

thanks in advance

 

Curious, how much cam and cubic inches?

My SSI B-rotor (full bottom opening, std helix) is pushing out 31 PSI at 27% OD on a 568....

 

Remember that the amount of fuel going thru the blower also changes the boost and temperature reading.

 

1.56 overdrive times an Engine RPM of 9000 is 14,000 rotor RPM. Were these cars running 9000 engine RPM?

 

Without supporting data I beleive the old guys that the old blowers were best run in the 30's.

We ran our 80's vintage LF 8's at 45% but I have no data supporting good or bad.

 

With more OD, the fuel to the ports should be increased to help cool the air in the blower to enable it to be cooled off by the time it hits the valves.

That is my opinion. I'm running 70/30 hat/ports in order to keep my inlet temps down.

YMMV

 

"the fuel to the ports should be increased"
then later
"I'm running 70/30 hat/ports"

So your running more fuel above the blower, correct?

 

Back then we used to leave at 5500 and run close to 8300-8600 shift

What I'm trying to explain is that at that date we only understood that more overdrive was more power . We never had a blower that we put more overdrive and became less powerfull. Then we switched to screw blower and after 10 years we are back now in promod but with HH blower and now people are telling us only 30 overdrive becase of heat but nobody has been able to tell me exactly at what point heat became an issue ....

 

Yes. I run most all the fuel up top, then tune plugs with the ports.

 

do you take a manifold temp. reading??..when you fire it up in the pits a good temp to set it at is 89.9 deg. Dave
www.myspace.com/daveloweswr

 

intake temp

I have not measured it yet lacking the funding for a data log.I have a egt logger this is in a lake/race boat less is more on electronics this engine is a 468 pro topline heads 12.5 comp intake 410@700 306 @ 7oo ex. oddy cam 722 lift and that is all I know about the cam they grind off the grind numbers seems to work ok 105 deg f and 5000ft DA made 30psi at 40 over @ 7500 just wondering how far I can go with the OD thanks Craig

 

I think I'd be sending in the blower for service, and having the tolerances checked.

That blower should be making a hell of a lot more than 30 PSI at that OD.

 

yes, mine is about 90 degrees at idle and will get to about 150 right about a 2 seconds into the run. ALlL is new right now so will need to make a full run to give actual full run info.

 

What size hat and port nozzels do you run? / are they flowed ?