Blown BBC combination help

Newbie to the site, and would appreciate your input.
I am strongly considering selling my SC combination and building a blown BBC for my 90 Spitzer 240" hardtail. I don't get to race as often as I would like to but am ready to step up the program. I have a good Tall deck block that is 4.310 and intend to use a 3.75 stroke. I have a good set of Lunati ProMod Steel Rods 6.660 with a 1.77 rod ratio. I plan to use my Brodix Big Brodie 2's with 2.300 and 1.880's and for now and stay with a stud girdle and Crane rockers. I plan to run a Enderle Big & Ugly on alcohol and am unsure what size blower, enderle plate diam, camshaft and pistons to buy. Are the steel rods a good idea?

With this smaller cubic inch package, what compression ratio should I be looking to run, how much boost is reasonable, how much power would I realistically be making so as not to tax my PG. (JW Bellhousing, stock case, 8" converter, 1:76 set) Will a 8" live?? MW , Big pinion, 35 spline, thru bolt aluminum center section, 4:56 gears, and what kind of rpm's is this little motor going to run??

Again, I'd appreciate any help

 

Small BBC

Hi Catman, Wildcat here ! we run a more conventional setup BBC in 509 (4.5/ 4) and 532 (4.6/ 4) but would assume that there would be similarities between the combos. We run 11:1 static, 30psi boost currently with a HH 10-71. You would be fine with a good 8-71 and that should get you 30-40psi boost. We used to run steel rods but have run alloy rods for the past 6 years or so as they provide more cushioning than the steel rods. They do have a limited life span so you need to limit the number of runs based on the manufacturers recommendation. We run a fairly mild cam with 116 seperation (780 lift) and pull 8,000 rpm. I would NOT run a 8" convertor, we run a T400 with a 10" and have never had a failure and thats in a heavy car (3300lb)

 

What kind of duration on the cam? Is your 4.6 bore block solid? Any issues with cylinder distortion or ring seal with it? Thanks in advance. I agree with you on the converter, a lot of blown small blocks run a 9" converter and most of the big block stuff is 10" or bigger.

 

I've been told a 8-71 would be good, what aboutspecs?? Cast rotors or billet, stripped, hard anodized??, etc. Are they good investments??

With the steel rods, is it the loads on them or cycles?

 

I like to compare it to the difference between hitting your crank with a Steel hammer or an aluminum hammer

 

Well put... Does a smaller cubic inch combo at higher boost perform any better than a larger cubic inch package?

 

I run a cast iron std deck .060 over 427, 3.75 stroke BME rods, 11.1, bb2x heads, BDS stage 4 8.71. At 40 over i am getting high 20's to low 30's for boost (34 new) and have run a best of 6.98 @ 193. Block is stock chevy with a full fill. Only real issue is the main caps move around a bit and need to be repaired every two or three years. I also use a Milodon gear drive and a RCD crank support. I am replacing the rods at or near 80 passes, shift at 7600 and out the back door around the same or less. I do like doing stupid burn outs and get carried away sometimes, Race pak says i've hit 9000 a few times. We guess HP of around 1250, I have been using this same motor since 2004. It's now a back up as I have built a couple of bigger quicker motors since but this one keeps finding it's way back in the dragster. The good thing about running this motor is it dosen't breaks the parts around it that are built to handle the 2000hp 540 I have. I bracket race so the quickest car isn't that big a deal but it sure is more fun.

Make sure you have enough ignition, I run mine on a MSD12 but if you don't already have one buy a MSD 20 instead, with a 14.71 a MSD 12 is marginal. I am also a big fan of the MSD 7730 power grid, makes thing easier.

Steve

 

Bbc

We use a MSD-10+ and LOVE it. I know its not the preferred way but the only mag that puts out more grunt is a 44. We run a HH SSI 10-71 as the overdrive is severaly limited if we go bigger than this. We are making 30psi boost at 32% over on our 532. Cheers from down under

 

Blown BBC

A good cam for that combo going back to the mid 1970s was a Crane R288-4133. I Don't know if that profile still exist today. With a smaller BBC, you will notice when the blower begins to fall off (recommend a 8-71). I would go with aluminum rods and quality piston ~11-1 compression.

 

Look into Transmission Specialties Tech-10 series of converters. I run one on my 20 lb boosted Top Dragster / bracket car . 4.56 sounds like too much even for 1/8 mile.



GK www.MotorSportsInnovations.com

 

options

blower would be your preference, either 871 or 1471. You will max out the 8 at 40% over and only make ~25# boast for a bds stage 4 with strips. you could go with more expensive 8 but by then you could get a 14 for the same price and always have more than you need and could probably get rid of easier in the future. what ever you choose it needs strips. many of us started with 8 and now run 14 so I would probably find me a good used 14 hi helix with pie opening to start with their not that much more than a new 8 from say bds.

some thinks to consider with the drive train also determine what blower your need. if you go with the 8 your current tranny would survive with an 9.5 or 10 converter. if you go with the 14 and even though you make the same boost as the eight you will have to upgrade to ringless shaft. not sure about the stock case but you could try before you buy another. An illustration is that I went from 871 BDS to 1471 HHR (hi helix retro) and changed nothing else and broke three vasco ring style input shafts at the hit in a row.

alot of the guys on here will say 11 or 11.5 and this will be safe. but if you buy an 8 and want to get more power out of it, some have started creeping up to around 13 and are watching the boost but this is working well for most.

I would put aluminum rods in it. I change my BMEs at 100 runs and don't turn motor more than 8000, the higher the RPMs the more frequently you need to change the rods.

If you choose 8 you need a 430 gear if you choose 14 you need 410 or 390 to help kill some power on the launch and save the tranny.

your going to be making between 12-1500 horsepower. need to run synthectic tranny fluid with a good cooler to keep the temps down.

get someone like gorr or FEI (sponsor on here) to flow your system for the start and give you a tune up and you will save a lot of trial and error at the track.

 

Thanks guys, All good info for me. I'm sure youhave saved me some headaches (especially the rods)

caseyspradlin you mention going towards 13:1 CR with a 8-71.. Is that with a big domed piston or a smaller combustion chamber??

 

Blown BBC

Catman, what type of blower manifold will you use?

 

Tall Deck with burst panel. Would look to BDS or TBS for reccomendations.... Your thoughts??

 

Its looking like Iwill be going to a ringless input, and a 10"converter. Prolly have to update the front pump also for ringless. Any suggestions on mfg. and stall

I do have a 4:11 gear set also.

 

I would get that info from someone that currently uses one or the other as I am sure things RE blower intakes have changed since I last raced (stone age). Back then many believed a blower manifold just held the blower to the engine. The basic Cragar was the norm for a BBC until the Wizard came out in 1980. It was a semi-tunnel ram design and we picked up .10 over the Cragar. It was hell finding a 14mm belt to fit the taller manifold on a Rodeck (tall block).

 

manifold

Contact Roy @ PPP on a manifold. He makes the nicest tunnel ram style BBC blower manifold on the market. He can be reached at 760-427-5838

I can send you pics if you like(or anyone for that matter). E-mail me @ rlmiersch@aol.com

 

ON the Shaft, I would go with Coan... I Twisted 3 TSR's before I switched to Coan...

 

Comp ratio

Catman sorry don't know about piston style. I might call BDS and get their toughts. As I remember they are suggesting this type of combo to some.
I would recommend TCI I have good luck with their stuff. Talk to Ondra x348. Also you would have to get new pump also or maybe just new front half depending on what you already have.

If you are in the market for a block I just bought a brand new merlin 3 with billet caps that want to sell now. No machine work. Search merlin on here and you should see it. $1900.

 

Larry...tried the e-mail address and it came back?
or e-mail me at SS3raceteam@yahoo.com
thanks,
Steve