Orange peel 871 blower

Hello: This is G***erman needing your help again. So I built this really neeto old 63 corvette g***er that has allot of history and it is pretty old
school I have a BBC 427 in it with a dougnash 4+1 runs great but not as
fast as it should be when I built motor 10+ years ago I thought I put it
together for 11.5 cr it turns out the heads I put on was 122cc anyway
my compression ratio is about 8.2 so I threw a Mike Kuhl 871 blower
and it is magnesium dow 7 coated and cragar intake. Ive never worked
on a supercharger but it went on great and it sounds good did a burnout
and it felt good I'm 25% underdrive I don't know what I should be running.
but i'm trying to from 11.30s to 10.50s I forgot to mention I like to go
to local cruise in on occasion it race in nostalgic cl***es. Thanks for your
help

 

Hi, what is your question?

 

more info please. And a specific question would be nice.
Is the blower stripped? you don't really want a stipped blower for streat use.

Injected or carburated? Did it behave correctly during the p***? How much boost?

 

Sorry for the lack of info but it got it started. Blower is teflon stripped
I have a 1000cfm b/g carb on it and I haven't had it down track yet
did burn out in long driveway. Thanks

 

You just want us to tell you have quick it's gonna be?

That's what the dragstrip is for

 

just wanted recomended underdrive ratio

 

teflons stripps are not for street use on a 8-71. Run it like u have it 25 % under will be fine

 

Still don't know exactly what you're asking? Are you looking for blower drive ratio, carb setup, timing, ????

Blowers are fun, but you need to know that your fuel system, timing and boost are all correctly setup. The carb should be setup for a blown application - such that if it has power valves, they are boost referenced . . . also, it is better to be a bit rich than too lean - you don't want to detonate it!

A teflon stripped blower is a race setup - normally you don't run teflon strips on the street . . . they're just going to wear out.

What cam are you running? What springs?

We need a lot more - starting with what help/questions you're asking us for?

B&S

 

Cam is 708/680 262/252 at 50 112 center carb has not been setup for blower yet springs are for 800 lift heads are dart 308 runners pistons are Kieth black rods are childs and albert crank 1969 gm steel crank headers are pro stock ****** 2.250 tubes
with Borla built in header muffler vertex magneto total advance is 38deg

 

Have you driven it enough to see how much boost it makes?

If you just have one 1000 cfm carb on it, you may need more carb.

you might also need to take some gear out of the rearend.

 

Rear gear is 433 tire diameter is 32.5

 

To finish question just trying to see what horsepower gain might be. As far as stripped blower on street its about 6 miles to cruise and take 3 times a year for
racing I only go about 6 times a year buget doesn't allow for anymore thanks for all the help

 

25 under with a 8-71 on a 427 should make only about 6 psi boost, which should increase power by roughly 30%.

If you set everything up right, it should do what you want. There's only one way to find out

 

At 12% under mine probably takes more HP to turn than it actually produces. You have low enough compression to up the boost some. Get it out and play with it, but... if you have not already done so make sure someone set up the carb for a blower. You do not want to run lean on the big end. (you already knew that didn't you?) If you are really looking for someone to give you a HP# I suggest you talk to one of the blower shops. You will have to know the boost number to even guess.

 

Just ran a psi gauge on it when in burn out went about 6500 rpm made about 6psi
will call shop tomorrow ask about carb just had that one on shelf and had to start it

 

I guess that chart I looked up on google was pretty accurate.

I'm getting about that much boost with a 3% over 6-71 on a 454. I've run my car with the blown engine and an almost identical unblown, there was 1 second difference in ET

 

Just what I was gonna say...

 

38 degrees total timing u will melt that bbc. try 28-32

 

thanks for your input if you are wondering why I bought a stripped blower it had just been rebuilt at dyers and the peice was right if I wear it out I probably can get new
rotors without? and it looks cool on the old school motor

 

I'll set timing down tomorrow thanks

 

B&M street blowers have Teflon in the rotors.

 

1000 cfm is plenty for 427" that is street and strip, it will cruise around nice and if properly tuned not loose much more et than two 750's on the track.

 

b&m blowers do not move the volume of air a 6-71 and up do. The bigger volume of air and psi the more heat you generate, on the street no good. Race and alky no preoblem.

 

Maybe, maybe not. If the heads have a modern chamber design, then 30 degrees would be about right. The old chambers can tolerate a lot of advance.

 

Okay - here is a stab. If you really want to make a bit more HP, then you'll want at least dual 750 HP style carbs - setup with fuel curves for your engine, cam, etc.. Blowers need lots of CFM to make HP - right now you're choking it off. I'd talk to Patrick at Pro-Systems . . . he'll make you a custom pair of them for just about what you'd pay for stock units at Jegs.

Hopefully those pistons are forged ones . . . and not any of the hyper or cast stuff - of you're asking for trouble. Keep the timing down initially and if you can afford it, think about some timing control to pull out some timing as the boost comes up. I'd probably start with about 30 - 32 total advance . . . to reduce the chances of detonation.

I think you should be able to reach your performance goals - as long as you can hook it up.

One last thing: After you run it a few times, check your bearings and see how the bottom end is looking. On a blown motor, I'd prefer to see some softer bearings and more oil clearance than you were probably running before. If it was mine, I'd run .00325 to .0035 or so on the front four and closer to .00375 to .004 on the rear. You want a lot of oil flow to cool the bearings -- and heavy oil. You can always put a new set of .001 LARGER clearance V series bearings in it - just depends how tight it is now.

 

Plus teflon hates ethanol. Won't last too long on pump gas and then the boost goes away. That is why you see a lot of B&M blowers that need to be rebuilt.

 

Running 6 lbs boost ain't gonna hurt much, guys....sheesh

 

here's the bearings out of my blown 454, after 40,000 miles on the street and a dozen or so p***es down various drag strips. around 6 psi boost, stock clevite 77 bearings, walmart oil, but it never saw much over 6000 rpm. Running around 35 degrees advance, plus vac*** advance, and no boost reference on the Holley 4777 carbs.

It's not rocket science.

 

Just depends how hard you flog it, what parts you have in it and how much boost! Lots of guys start out conservative, but they get the 'itch' to maybe just swap the pulleys and see what it does.

Best of luck, let us know how it goes!

 

I see a little pitting or flaking on the thrust cap bearing..... Maybe it's just a little dirt..