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Topic Review (Newest First)
01-24-2013 12:25 AM
F-BIRD'88 No the 8-71 is not too big. Strokin: how much horsepower is enough....
01-23-2013 10:50 PM
1932bantam way to much mass out front blower is already puttn a strain on the end without that damn big counter weight on the end of the crankhub then adding pulleys to turn other things really puts it out there. externally balanced I stay away from. blown or not
01-23-2013 07:28 PM
496CHEVY3100 A Properly machined and preped 4 bolt with aftermarket caps or straps,ARP studs in mains ,arp cap screw in good prepared forged rods ,something like C&A bearings ,high quality pistons ,good solid roller cam with maching springs & kit will live at that level.when i say Live engine producing this much horsepower has a SHORTER life than say 400 hp Also i think a $1500 assembly will not cut it.
01-23-2013 06:50 PM
strokin I do have a mid 70's block 4 bolt never been bored that I can use for this build, but just thought when buying a $2000 rotating assembly is another 1500 for a block to protect it all that much? Will a mid 70's 4 bolt take 650 hp? I would think so but always that hint of doubt. Also u mention 8-71 on sbc, is that not to big for sbc? This is all going in 87 monte ss 9" 3.89 spool, coilovers, 8 point cage, notched frame, 3" exhaust with 1 3/4 hooker headers. This car is mainly for show and street but does hit the track a few times a year. Only drive it 2 times a month if I'm lucky.
01-23-2013 05:40 PM
496CHEVY3100 Normaly the crank is not the weak link, the bolts and caps usually give up and crank gets blamed ,i agree with F bird on 383 ,mine is a two bolt big block ,but i have arp studs not bolts also billett caps knife edged crank,lightned and balanced with mallory I dont anticapet any problems with 7.9 cr alum heads and pump gas, Streetdriver, if you see this on trailor report it stolen.
01-23-2013 05:00 PM
vinniekq2
383

Quote:
Originally Posted by F-BIRD'88 View Post
A 383 crank has a inherently bad design characteristic. I won't use them in a 6-71 or 8-71 roots blown
motor, specificly, because of this. I'll build a 355 (thats just as powerfull and more reliable) or a 4.125" bore 400 block based 377 or a 406. Or go 427-454 BBC based.

I'd trust a stock cast GM 350 crank more than a 383 stroker crank in a roots blown application.

Engine builders will sell you what ever you want, cause thats what you want.
If they don't or won't, the next shop down the street will...so...

But....

If someone comes to me and wants me to build them a 383 stroker motor for a roots supercharger, I will pass on it. No thankyou.. I'll offer to build a equally power full 355 based roots blown sbc motor or a roots blown BBC or not at all.
first question, "why"?

second question: how do "you" build a 355 equal in power to a larger 383?
01-23-2013 01:32 PM
F-BIRD'88 A 383 crank has a inherently bad design characteristic. I won't use them in a 6-71 or 8-71 roots blown
motor, specificly, because of this. I'll build a 355 (thats just as powerfull and more reliable) or a 4.125" bore 400 block based 377 or a 406. Or go 427-454 BBC based.

I'd trust a stock cast GM 350 crank more than a 383 stroker crank in a roots blown application.

Engine builders will sell you what ever you want, cause thats what you want.
If they don't or won't, the next shop down the street will...so...

But....

If someone comes to me and wants me to build them a 383 stroker motor for a roots supercharger, I will pass on it. No thankyou.. I'll offer to build a equally power full 355 based roots blown sbc motor or a roots blown BBC or not at all.
01-23-2013 12:23 PM
cobalt327 That's my point. A 383 crank is not inherently bad. There are good and bad "383" cranks just like there are good/bad cranks of any stroke for any engine.
01-23-2013 11:27 AM
F-BIRD'88 The stroke length it self is not the issue. There is more to it than that.
01-23-2013 10:24 AM
cobalt327
Quote:
Originally Posted by techinspector1 View Post
Read this from Blower Drive Service...

"Flat tappet and roller cams are recommended for high performance applications especially where the engine will see high RPM's.
I'm thinking they left out Solid lifter, as in "Solid lifter flat tappet and roller cams are recommended for high performance applications especially where the engine will see high RPM's."

As long as the crank is good quality, there's not a thing inherently "wrong" w/using a longer stroke.
01-23-2013 08:48 AM
1932bantam yes i agree . he already had engine , so we tried it
01-23-2013 08:39 AM
vinniekq2 Many reputable crate engine builders will build 383/406/434 turn key blower engines.They use a callies crank.Just dont try to build powerful and cheap,leave that for the low horse power guys
01-23-2013 08:01 AM
F-BIRD'88
Quote:
Originally Posted by 1932bantam View Post
thing about the 400 you got to run that big heavy crankhub for ex balanced that and pulleys for alt etc. puts alot of strain on the end of the crank. As far as quench no need to worry about it on a blown engine. We just had a crank hub twist off, bent end of crank on 383 idling was running a spacer behind blower pulley, not a good setup
I would never use a "383 crank" in a 6-71 8-71 blower motor.
Any 383 crank. But especially any off shore crank.

And a lot for just these reasons, and more.
The stroker crank just does not pay off in a blower motor.

If I was going to build using a 4.125" bore block I would just use a 3.48" stroke 350 crank or the stock GM 400 crankshaft.

The 355 engine base is the way to go.
If you must have more than what this will deliver, jump to a big block engine.

If you are starting from scratch and don't have a 350 engine core the GM ZZ4 350 short block is a great base-start point for the build.
01-23-2013 07:42 AM
1932bantam thing about the 400 you got to run that big heavy crankhub for ex balanced that and pulleys for alt etc. puts alot of strain on the end of the crank. As far as quench no need to worry about it on a blown engine. We just had a crank hub twist off, bent end of crank on 383 idling was running a spacer behind blower pulley, not a good setup
01-23-2013 07:35 AM
F-BIRD'88
Quote:
Originally Posted by strokin View Post
So you don't see any advantage to running a 400 vs 355 even though they will all be brand new parts? Obv we've all heard of typical problems with a 400 but even with dart block and all aftermarket parts?
Adds a lot of extra cost and complexity to the build which won't be returned
in real street strip performance gain.

The 355cid "keep it simple" blower motor is powerfull and reliable and more than delivers the goods.
A after market block is not required.
You could build a big block 454 based motor for the money it will cost you.
Way better return in both performance and reliabily, with a big block . VS a big cube SB w aftermarket block etc.
Again simple cost effective brute strength and reliable supercharged power with a BBC, when you need more than 650-700
hp supercharged street power. Its hands down better to go this path.

Is 650+ horsepower and 500+ ft/lbs torque enough?
The 7.5:1cr pump gas 355 6-71 or 8-71 delivers this. Real simple to build.
Remember, this is more than enough to shread a 9" rearend. And split a trans case in half.

why make it more complex and costly than it needs to be.?

How much power/performance are you really after? how will it be used? purpose....
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