im saving up money to build a pontiac 400 into a 472 stroker, but i want it blown, with a roots style. i wont be running a hood either. my question is that what makes the blower whine "lope" and sound like it almost cuts off the engine for a second? i hear 6-71's and 8-71's with a constant whine, but what makes the engine nearly "cut-off", is it the teflon stripc, the size of the blower, or the screws?? please school me on this, i want to get a blower thats very intimidating at a stoplight, im not too worried about the driveability, she will only be driven to the track and local shows which are all very very close to me. and can this be done on pump gas or 100 octane?
i think what you are referring to is when the engine sounds like it's revving up, and down at idle...making the blower whine speed up and slow down. i think that is caused by cam choice...i don't think it has anything to do with the blower itself. by no means am i an authority on blowers...i've never owned one. i just think it's the cam that makes it sound like that.
The blower whine is actually created by the choice in belt(s). As beetlejuice55 said, the "lope" you are refering to is a result of the cam grind. To achieve what you described, I believe that a substantial fast lift is needed. We had a mud racer that did just this. The cam lobes were not egg shaped, they were neary rectangular with rounded off corners and offset. Pretty wild cam to look at.
it would be the cam that affects the idle sound, so when you go to buy your cam just tell them what youre lookin to do with the idle sound and they should be able to get you a cam that will work with the build and also give you the sound you want
from superchargersonline.com "Compressor surge is a problem that affects most superchargers and develops when the supercharger is creating boost, but the throttle shaft is closed." So besides the cam, if your idle is way down, how you carb is set up (small idle feed restriction), and you are creating boost, you will get the surge. If you really want to hear a loping engine, y'all need to get to some drag boat races. Those engines are a whole lot nastier than anything I have heard at major drags (gators, or winter), or nostaligic raceing ie: bakersfield, it probably has something to due with the drag boats real low idle the only car I have heard that even comes close to those is the pro-lube pro-stocker that hits some of the shows in CA. I think comp cams now makes something called the thumper, to give you that lope, like someone suggested talk to the cam manufacture and see what they say. Good Luck Mike
Another factor is how the blower is sized & then over/under driven for that engine. A big blower, underdriven will do this more than a small blower overdriven. The actual whine comes from the belts - some folks actually drill holes in the lands of the pulleys to reduce the whine...
On mechanical injection barrel valve adjustment will cause this.On EFI Idle AIR Controlve adjustment will cause it.On carbs not enough idle fuel. Gemini EFI
yes - I have a very small cam in my 283 with a 471 and it will surge when you slow the idle RPM below 800 RPM. It will almost cut off and then surge. I have heard a blower will calm the idle of a cam that would have a nasty idle normally aspirated.
Gemini & Tudor nailed it. Idle mixture & rpm effect idle quality, or as your goal seems to be, lack of idle quality. Odd to see people say that supercharger "whine" comes from the belt. Is this true? I always assumed it comes frome the gears in the front of the case.
Yup, the gilmer belts and the cogs on the pulleys make the whine. I can hear the rotors turning in mine if I listen for it. I think the V-belt drives run quiet. The gears probably make some noise too. I think the looser the belt the less noise it makes too. I think I remember reading on here the noise comes from the air getting trapped between the pulley and belt cogs. That is why they drill holes in the pulleys to make it quieter. I think they said it only reduces the noise by half. If I walk to the street when mine is running, I can only hear the whine and I've got zoomies! Its loud
I did not know that! Folks drill holes to make it quieter? Wow! why would ya do that? I like my shit to be noisy!
I think the air under the belt steps might actually lift the belt off the pulley in an extreme racing deal. So drilling relieves the pressure. And the Gears in the GM blowers have a pretty steep helix, So they would be very quiet, unless worn. The air going into the blower is also very noisy at WOT. Frank
Yeah, thats true. They are not straight cut gears, but I always assumed that this was the source of the lovely noise. Funny thing is, my exhaust is SO LOUD, it has gotten hard for me to hear the whine from behind the wheel. Folks hear it coming but not so much going. At least I couldnt. So I installled a "noisy" gear drive to make some extra racket. Even I can hear it now
Hmmmm....Kerry has V-belts and his wines. Doesn't it? Hell, come to think of it, it might not.... SSCatalina. Go to the Performance years Pontiac board (performanceyears.com) and find Pontiac Dude. (Kens Machine, Melbourne Florida) He is a big time Pontiac guy and is a dealer for BRC pistons. Scrape up 600 bucks and have him order you some bad ass pistons. Custom built to your head cc with extra thick top ring lands. Honestly, a regular 400 inch Poncho at 10lbs of boost will make you shit your self with out the extra expense of a stroke kit. Spend your money on the bad ass pistons and some good rod bolts and you will never notice the missing stroker kit. Unless you have lots of cash, then get the pistons AND the stroker... PS. My 400 inch Poncho was only at 7lbs of boost at teh HAMB Drags and ran 121.5mph spinning the length of teh track. Good luck and holler if you need anything. -Abone.
When we used chain drive (way back when) the blowers whined. I think it comes from the gears, but not sure. I am sure that the surge in idle speed comes from a lean condition caused by the boost and mixture. Fatten it up and this will stop, but plugs may get fouled.
Blower surge is a rich/lean condition. Blower lope is the cam, compression and idle speed. The gear whine is from the gears(2 sets of them) The blower sucking in the air at rpm is another sound you get as with the belt. Its not good to let you it surge at 800rpm or less.
this is from BDS's website - <TABLE cellSpacing=2 cellPadding=2 width="95%" border=0><TBODY><TR><TD class=boldblack vAlign=top align=right bgColor=#d2e1fc>Can blower whine be eliminated or made louder?</TD><TD bgColor=#efefef>Blower whine can be increased or decreased by tightening or loosening the blower belt tension. CAUTION! Improper belt tension can cause severe belt, blower, and engine damage. It is not recommended to adjust the belt to get the sound you want. Worn pulleys and belts as well as mis-machined pulleys can contribute to blower whine.</TD></TR></TBODY></TABLE> I am not sure what it is!! I just like it!! ha ha A 400 inch Poncho with 10 lbs of boost will make you shit yourself! that's great.
Just put in one of those dumb gear drives and work the pedal when you are cruising, its the cheaper way to get that poser sound.
S/SCat check with the guys at pontiacheaven.org to get the 411 on blown Pontiacs. Gary Dyer at dyersblowers.com can build you anything you want in the way of blowers. Hope this helps. The surge is mostly cam.
http://www.youtube.com/watch?v=JPI0aAXI6KY if this link works, i love this sound...maybe not so crazy since i cant afford a motor like that but i love the lope it has....thanks for all the information, i will check out that pontiac engine builder and head down to the speed shop and ask about the cam choice.....cant wait to take my car out to the sonic here with a blower and crazy idle hahahahah . time to scrounge some money......
http://www.youtube.com/watch?v=4m2FXFuMFJk&feature=related http://www.youtube.com/watch?v=zkiPUNSLeTQ some drag boats, love them too, crazy motors
Friend of mine built a T-bucket in the 60's and put a gutted 6-71 blower on it and a Holley carb inside the case. No gears, no rotors and that gilmer belt whines just like a "real" setup. You can't tell it from a functional one, noise wise. Frank
There are many different whines from the blower - the loudest is the cogged belts. The gears are deep helix, so do not whine much (just like transmission gears).
From the videos you posted, what you are looking for is the rapid increase/decrease of the idle RPM. Mostly, what you are hearing is the air/fuel mixture going rich/lean...rich/lean. My blown Poncho will do that if I set the idle rpm too low. In my situation, it is the Carter carbs needles coming off teh seat looking for more fuel. Then, it has enough and shuts the needles again. Over, and over, and over.... While it sounds kinda bitchn...it is a total pain in teh ass on the street, as sometimes it will die when I put her in gear or roll up to a stop light. To remedy this situation, I bump the idle up to about 1000rpms. She idles nice and smooth, and is waaaay more driveable. Good luck, -Abone.
Lemme try this... http://www.youtube.com/watch?v=y4biorTaGzM Hey..I think it works... Some kind HAMBer taped my little car running at teh hotel at teh HAMB Drags. Notice the lack of idle surge...She sounds like a normal hot rod motor. Good luck, -Abone.
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