496 BLOWER MOTOR

« **on:** March 07, 2011, 06:57:02 PM »

JUST GOT A MOTOR SHOULD HAVE DONE MORE RESEARCH BEFORE I BOUGHT IT.THE MOTOR IS BBC 496 8.9 TO 1.SET UP FOR BLOWER 871.I DONT HAVE A BLOWER,BUT HAD A FRIEND MECHANIC TELL ME IM F?$#ED THE MOTOR WONT RUN WITHOUT THE BLOWER COMPRESSIONS TO LOW.SO MY QUESTION IS WHATS A QUICK FIX????I HAVE THE LONG BLOCK NO INTAKE.WANTED TO RUN CARB ON A TUNNEL RAM. HOW CAN I FIX THE COMPRESSION ISSUE..

« **Reply #1 on:** March 07, 2011, 07:07:57 PM »

Someone had a complete blower setup for $2500.....from intake to carbs....water cooler and pulleys included....

If thats not in your budget, I suggest trying to sell it and make your money back and get the right motor for your needs.

« **Reply #2 on:** March 07, 2011, 07:11:47 PM »

Buy a set of srp pistons for $600 and call it a day, or run it like that. Hell, if it were mine I'd leave it alone and run it on 87 octane....the difference between 9:1 and 10:1 isn't gonna be much more than about 20 HP. Don't worry about it...go have fun.

« **Reply #3 on:** March 07, 2011, 08:24:40 PM »

Quote from: PBWOOD on March 07, 2011, 06:57:02 PM

JUST GOT A MOTOR SHOULD HAVE DONE MORE RESEARCH BEFORE I BOUGHT IT.THE MOTOR IS BBC 496 8.9 TO 1.SET UP FOR BLOWER 871.I DONT HAVE A BLOWER,BUT HAD A FRIEND MECHANIC TELL ME IM F?$#ED THE MOTOR WONT RUN WITHOUT THE BLOWER COMPRESSIONS TO LOW.SO MY QUESTION IS WHATS A QUICK FIX????I HAVE THE LONG BLOCK NO INTAKE.WANTED TO RUN CARB ON A TUNNEL RAM. HOW CAN I FIX THE COMPRESSION ISSUE..

8.9-1 compression will run fine. If you are worried about it, and don't have a camshaft yet, let me get one ground for you that will up the cylinder pressure. I have done it before with a GN race engine that the guy wanted to run without the blower,, ran 6000 rpm in a 21' Rayson craft. You are perahaps only 1/2 a compression point what I would normally build a pump gas NA engine with iron heads for a jet boat, so don't be concerned.

« **Reply #4 on:** March 08, 2011, 07:39:15 AM »

Are the pistons dished? Flat tops with a 118cc head .040 gasket yields about 8.4-1 give or take. Changing to a shim would yield about 8.8. How are you getting the 8.9? Post a pic of the pistons. Throw down some of your specs. Combustion chamber or casting number of the heads. If you can't post a pic of the pistons paint us a verbal picture (huge dish, small dish, flat top, tiny dome, small dome) you get the picture.

A quick fix for the compression would be a 250 shot of NO2! Just my .n02!

First thing is to find out where your starting point is. Casting numbers and a description of the pistons.

P.S comp ratio was figured as 4.25 bore 4.25 stroke 4.500/.040 head gasket -.016 deck -2cc valve relief

« **Reply #5 on:** March 08, 2011, 07:44:46 AM »

I have a set of VERY lightly used 4.310 6.135 4.25 flat top JE pistons that I would be willing to trade for comparable dished pistons.

« **Reply #6 on:** March 08, 2011, 09:59:12 AM »

Quote from: HomeBlown57 on March 08, 2011, 07:39:15 AM

P.S comp ratio was figured as 4.25 bore 4.25 stroke 4.500/.040 head gasket -.016 deck -2cc valve relief

Most single valve relief pistons that I have used are -3cc.

Problem is, you (and probably he) do not know deck height or which gasket was used, or even the combustion chamber size. Figuring at zero deck with a 118cc chamber and a smaller bore gasket, it could be 8.74 to one.

My point was, it can be made to run fairly decent if he isn't needing to extract every last horsepower from it. The GN engine that I re-cammed was perhaps 8-1 compression.

« **Reply #7 on:** March 08, 2011, 10:37:16 AM »

Even at 8-1 I would run it. 87 octane is only about $4 a gallon right now. So run it low and boost it later. Did you get a cam card with it? I would be interested in the cam if it is around .630 and 114 LSA flat tappet.

« **Reply #8 on:** March 08, 2011, 05:50:22 PM »

researched the motor heads are 113cc open chamber oval ports.the pistons look flat top (looking through the spark plug) alot of porting on exhaust and intake.exhaust 2 1/4.1/4 stroke over eagle crank,.60 over cyl.,eagle h-beams,schneider cam 296 .590 lift.again had a blower on it with 10lbs boost.I am still weighting the costs im leaning blower.but if its cheaper to through intake and carb i just want water.not real familiar with blowers.but theres a first for everything.they sure look purd cool...

« **Reply #9 on:** March 08, 2011, 06:58:50 PM »

put a blower on that thing money bags

« **Reply #10 on:** March 08, 2011, 07:10:54 PM »

Custom ground cam with a longer duration on the intake, big intake manifold and smaller headers...Let Her Buck!....

It should run hard

GT

« **Reply #11 on:** March 08, 2011, 07:39:49 PM »

Quote from: PBWOOD on March 08, 2011, 05:50:22 PM

researched the motor heads are 113cc open chamber oval ports.the pistons look flat top (looking through the spark plug) alot of porting on exhaust and intake.exhaust 2 1/4.1/4 stroke over eagle crank,.60 over cyl.,eagle h-beams,schneider cam 296 .590 lift.again had a blower on it with 10lbs boost.I am still weighting the costs im leaning blower.but if its cheaper to through intake and carb i just want water.not real familiar with blowers.but theres a first for everything.they sure look purd cool...

If that motor is static 8.9:1 and running 10lbs. of boost it has an effective comp. ratio of 15:1......I hope he was (previous owner), or you do plan on running very expensive fuel.... like C12 or higher ($10 plus dollars a gal.)

« **Reply #12 on:** March 08, 2011, 07:40:09 PM »

Standard SCJB offer of $50. I'm just trying to help you out. That should solve your dilemma!

I could be interested in the cam. Do you have a degree wheel and dial indicator that you can use to measure the Lobe Separation Angle. This would help you to determine if it will be useful for your N/A application or my Forced application.

Did you get a cam card?
Oh, yeah and did you get a cam card?

« **Reply #13 on:** March 08, 2011, 07:47:02 PM »

he has a schnyder cam and yes he has a cam card ill call him right now and tell him to post specs.SUMMER IS ALMOST HERE SUCKA BETTER HURRY

« **Reply #14 on:** March 08, 2011, 07:48:26 PM »

I will be coming to Ramona soon. If you do not have a cam card, we could make one in about an hour with the heads on and not disturbing anything else. The cam info is paramount in every package and a good blower cam would not be a good N/A cam. If you would like the help let me know. I will be down around 3/15-3/18.

« **Reply #15 on:** March 08, 2011, 07:49:19 PM »

Crap I was posting while you were.

« **Reply #16 on:** March 08, 2011, 07:54:02 PM »

card reads intake &exhaust valve lift.590 duration 296.intake & exhaust camlift .347 duration @.50 camlift 262.lobe seperation 112 degree intake lobe to 110..chinese to me wtf does this mean????are you guys sayin if i get the blower at 10lbs. boost i have to run c12.

??

« **Reply #17 on:** March 08, 2011, 08:01:17 PM »

Quote from: PBWOOD on March 08, 2011, 07:54:02 PM

card reads intake &exhaust valve lift.590 duration 296.intake & exhaust camlift .347 duration @.50 camlift 262.lobe seperation 112 degree intake lobe to 110..chinese to me wtf does this mean????are you guys sayin if i get the blower at 10lbs. boost i have to run c12.??

home blown do you mind explaining the comp. ratio with boost to pbwood......I cant type worth a crap.

« **Reply #18 on:** March 08, 2011, 08:16:25 PM »

Quote from: Dirty Air on March 08, 2011, 08:01:17 PM

home blown do you mind explaining the comp. ratio with boost to pbwood......I cant type worth a crap.

oops! did not notice that homeblown57 signed out.......for every lbs. of boost you go up, your comp. ratio goes up as well with a safe max at 12.4 :1 for 91 octane pump gas witch leaves you at at about 5.5 lbs. max before detonation!....see chart http://www.blowerdriveservice.com/techcharts.php

« **Reply #19 on:** March 08, 2011, 08:51:15 PM »

ok i think im getting it.correct me if im wrong then if i ran a 871 at 8 lbs. of boost that looks like what im getting after???

« **Reply #20 on:** March 08, 2011, 09:01:43 PM »

:screwy:sh?t im a little slow.ok so 5.5 with the 871.now how much HP will that create?? and im sure this is a dump question how do i now what carb to run cfm wise???

« **Reply #21 on:** March 09, 2011, 06:43:56 AM »

PB, are you thinking of running a blower now? I think the cam is a happy medium between N/A and Blown. Others may disagree. I would like to see 114 lobe separation blown and 110 or 108 N/A. I like the cam for a tunnel ram now and blower later. You should keep it.
I think that you need to degree the cam and advance it two degrees from what is suggested for the tunnel ram. I would move the intake center to 108. Then put it back when you run the blower. Blower cams open the exhaust earlier and open the intake later.

Everyone will differ a bit on this. But if everyone chimes in, you can take it all in and make a choice based on ALL opinions.

P.S. $3000 8-71 delivered with a twin 4150 top. I am just saying! It's available.

Boost is like sex. You know it is cool before you get it. Then when you do, you can't get enough. Then it is all that you can think about. Then you want everybody to have it, BUT you always want to have a little more than the next guy!

I'm done.

« **Reply #22 on:** March 09, 2011, 07:42:54 PM »

pb is out of town right now but he wants to know if it has the pulley set up

PBWOOD

Brad @ SCJB

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