BBC is it really necessary for 4 bolts or stds good enough?



BBC is it really necessary for 4 bolts or stds good enough?

Postby riv187 » September 26th, 2014, 1:54 pm

Hi
New here to forum. I have a 1969 front engine dragster I bracket race with. Currently sbc with hilborn. This runs well and shows 560+ hp on a 400 (bored .060) 2 bolt main block with studs and Hard-blok in bottom end. Has 14-1 on methanol. Car weighs 1531 with me in it,,and 5500 stall conv. and PG tranny.

My next engine is a 496,13-1, methanol, also hilborn injected with decent roller cam. Block is 2 bolt mkIV. I bought studs for top and bottom. I'm shooting for 780hp.
Will 2 bolt block be OK with the studs? I've thought about putting homemade 4140 straps on top of caps with longer studs to match. Good idea or waste at my level? Putting Hard-Blok in bottom of BBC good like I done on my 400SBC ?

I run the sbc 7200 rpms at finish and the cam I have for BBC will like same rpms.
I've heard the 4 bolt argument vs 2 bolt,,,but have never seen a failed 2 bolt BBC. I have the block bored to match my pistons now,,,and consider adapting stock 4 bolt caps,,as well as splayed centers..but wonder if its over rated just as my SBC 440 running 2 bolt stock caps is running fine on 14-1 at over 7K. Money isn't easy and every bit saved is appreciated.
Thanks for responses.
riv187

 
Posts: 3
Joined: September 26th, 2014, 1:05 pm

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby Indycars » September 26th, 2014, 3:36 pm


First Welcome to the Forum! :)

Let me say I can't speak from experience, but below is something to
think about.

With a 4.25 inch stroke that's going to put you right at 5000 FPM Mean
Piston Speed at 7000 RPM, which is pretty high.

If you have a piston & pin that weighs 500 grams and turn that 496 to
7000 RPM, then just one piston is going to weigh over 4400 lbs. That's
4400 lbs trying to pull the rod apart. At 7200 RPM it jumps to 4670 lbs.

If you know what a good number for your pistons, then you can calculated
the stresses for your engine more precisely by using the Excel spreadsheet
linked to below.

viewtopic.php?f=99&t=6636

More calculators below:

viewforum.php?f=99

I guess you know someone is going to give trouble for not having any
pictures! :lol: And just how fast does that monster go in the 1/4 mile???

Riv187PistonStresses.jpg

PistonSpeed02.JPG

You do not have the required permissions to view the files attached to this post.
Rick
Too much is just enough!!!

- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
- Need a Dynamic Compression Ratio Calculator: viewtopic.php?f=99&t=4458
Indycars

User avatar
Forum Admin
Forum Admin
 
Posts: 4424
Joined: May 25th, 2010, 8:58 am
Location: Yukon, OK

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby riv187 » September 26th, 2014, 4:40 pm

I appreciate reply. I have Wiseco pistons, but haven't weighed yet.
I race 1/8 mile as that is what almost everything has went to in Florida. I go 130 in 1/8 with small block and 5.20s. My 60 ft is 1.18s now. Should be around 160-165 in 1/4,mid to low 8s if I went to a 1/4 track. Hoping the 496 will get me 4.70-4.80s in 1/8th. or 7.50s in 1/4 mile and 178mph.
A good source you mabe aware of for calculators.
http://wallaceracing.com/Calculators.htm

Here's pictures if they load..one before went back to wheelie bar....Stand it up and it would stay there till you lifted ..nearly flipped it over twice. Looks cool for crowd but sucks for ET and consistency. I tried adding weight to front and balancing it 2ft off at launch,,but still not real consistent. With wheelie bar it keeps front end down about 6-7" high...but all motion is forward...and reactions are more consistent,quicker 60s and ETs lower.
The BBC pictured has the heads and injection I'll be using,Hilborne and CFE cnc canfields.
I heard,go DART block,,,but the weight is a big factor for me.
Thanks for input!
Brian
You do not have the required permissions to view the files attached to this post.
riv187

 
Posts: 3
Joined: September 26th, 2014, 1:05 pm

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby Indycars » September 26th, 2014, 6:46 pm


I'm just getting ready to go in and eat, but tomorrow I'm sure I can up with
something smart to say.

Rick
Too much is just enough!!!

- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
- Need a Dynamic Compression Ratio Calculator: viewtopic.php?f=99&t=4458
Indycars

User avatar
Forum Admin
Forum Admin
 
Posts: 4424
Joined: May 25th, 2010, 8:58 am
Location: Yukon, OK

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby grumpyvette » September 26th, 2014, 10:20 pm

as Im sure your aware the difference in total weight between the SBC you ran and the BBC your thinking of running is in the neighborhood of about 80lbs-140lbs different depending on components selected, that weight is mostly from larger and stronger parts , but there are limits to what the stock component will endure over the long haul.
(even with the stronger ARP main cap studs)
Ive personally built a couple dozen 489-496 big blocks, some with stock chevy blocks, a few with DART blocks and a couple with WORLD blocks I vastly prefer the DART BLOCKS, they have at least in the examples I worked with been well machined and had zero issues.
Id advise you to be more concerned with maintaining a reasonably thick and rigid cylinder walls as maintaining ring seal , than pushing the bore size to max, and on a race engine Id get the compression ratio up in the 12.7:1-13.7:1 range.
that extra displacement of a 496 with its 4.25" stroke and 6.385" connecting rods and the increased component weight potentially increases the stress on the main caps and bearings to far higher levels than the 3.75" stroke of the 400 sbc engine
while theres no question that the chevy big block , block is fairly strong pushing a 4.25" stroke crank to over 6000rpm and expecting the two bolt main caps to still prevent movement is in my opinion asking for rather UN-reasonable demands, yes theres a hundred guys that build 427 chevy big blocks and spin them to 6000rpm plus all the time and get good results, theres even a few guys doing it with a 4" 454 crank or a 468 BBC in a two bolt block, but the stress goes up rapidly as the stroke increases and the rpms increase and stress is cumulative.
you may get away with something for months, but thats no guarantee your not damaging the bearings or stressing the block , in a way that WILL eventually cause it too fail.
there are SPLAYED MAIN CAP conversion caps to convert a 2 bolt block to a splayed 4 bolt config, these add rigidity, and tend to increase durability.
theres ZERO QUESTION in my mind that converting the center 3 main caps to splayed bolt config and using ARP main studs and outer splayed cap bolts increases block rigidity enough to be worth the added cost if your building a 496 with that 4.25" stroke and intend on spinning it over 6000rpm, and I would strongly suggest the AFTERMARKET connecting rods with ARP 2000 series 7/16" rod bolts, as a good minimum precaution
http://www.summitracing.com/parts/mil-11200

http://www.summitracing.com/parts/sca-2 ... /overview/

viewtopic.php?f=69&t=7267&p=24723&hilit=splayed#p24723

viewtopic.php?f=51&t=1014&p=24525&hilit=splayed#p24525

http://www.summitracing.com/parts/sca-6638522a


A FORGED BIG BLOCK PISTON CAN EASILY WEIGHT 600-700 grams , the connecting rod a similar weight, thats over 1200 grams, far more than the 500 grams listed in the calcs previously above, every one of those 8 pistons and rods effectively adds over 5 tons of stress to the main caps as it changes direction at 6600rpm
http://www.jepistons.com/Catalogs/Autom ... t_top.aspx

viewtopic.php?f=53&t=204

viewtopic.php?f=51&t=125

viewtopic.php?f=51&t=10472

viewtopic.php?f=53&t=852

viewtopic.php?f=53&t=510

viewtopic.php?f=53&t=1168

viewtopic.php?f=53&t=509

viewtopic.php?f=51&t=710

viewtopic.php?f=53&t=341
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby 87vette81big » September 27th, 2014, 8:11 am

Internal rotating stresses are proportional to engine rpm increases or decreases.
With a 4-1/4 " stroke I think you may find best overall performance in the 6000-6200-6500 RPM Shifting and Trap Speed range.
I think a 2-bolt Mark 4 will work OK if you stay within these guidellines.
Aluminum rods weigh slightly less than a Steel rod of similar center to center specs.
Titanium even less but its out of your budget.
Bill Miller Engineering makes the best Aluminum rods.
What I would choose to use in your Diggger.

To obtain a 178-180 Mph trap speed with the same current gears used you will have to Rev the engine much higher than 7k.
The 496 will make another 100-150 ft/lbs torque over your 400sbc.
Best to gear your Digger higher numerical.
In a Pontiac 400 , 4.10's may work best.
455 with 4.21"stroke likes 3.08-3.23. And they run faster in 1/4 mile by .50-1.5 seconds built correct.

Recalculate for gears to put you in 6200-6500.

With long strokes and cubes Pull the Gear. It will and effortless.
87vette81big

User avatar
 
Posts: 3278
Joined: February 28th, 2012, 12:34 am
Location: Central Illinois

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby Indycars » September 27th, 2014, 2:02 pm


Thanks for the photos, that must be one wild ride, especially with the wheels
5 feet in the air!!!

The first calcs were done with a 6 inch rod, which will make it looks worse
than the 6.385, but the accurate piston weight more than makes up for that.

It's just incredable to think that the piston is going from zero to 93.3 mph
and back to zero in just 4.25 inches...... Wow!

Calculations with the newest numbers at 7000 RPM.

Riv187PistonStresses01.jpg


You do not have the required permissions to view the files attached to this post.
Rick
Too much is just enough!!!

- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
- Need a Dynamic Compression Ratio Calculator: viewtopic.php?f=99&t=4458
Indycars

User avatar
Forum Admin
Forum Admin
 
Posts: 4424
Joined: May 25th, 2010, 8:58 am
Location: Yukon, OK

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby 87vette81big » September 27th, 2014, 2:17 pm

With a Short rod of 6.385 when compared to 6-5/8 or 7" common in other Tall deck Big blocks, cylinder wall loads are pretty high.
Piston speeds secondary issues to me.
Working with 2-bolt mains & limited budget $ to get the job done.
6,200 Redline work nice if possible.
87vette81big

User avatar
 
Posts: 3278
Joined: February 28th, 2012, 12:34 am
Location: Central Illinois

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby riv187 » September 27th, 2014, 6:19 pm

Hi
each I'm reading everything twice. I respect your advice as I have read and re read post to others that help me learn. I got the scat pro comp rods as they look like quality, cheap for the money,and lighter than Hs. The fact Vizard used and recommends them in both big and small blocks sold me. I use the 5.7s with std 8740 bolts in my SCB. I did not see anywhere in vizards books or articles about ugrading to arp 2000 bolts. I called ARP tech and he said 8740 is probably sufficient,,but the 2000s are nice insurance. I'm back forth on that one.
I'm counting on gaining about 80lbs going to BBC with aluminum heads vs SBC with aftermarket iron( EQ215/50ccchambers). My car bounces around in pits and on return road as the frame is long,moly,and no suspension. The extra weight may really be a nusance in the pits with rough pavment. When this car wheelied before,,it was a climbing action that went up till sparks shot from the rear frame and I lifted gently to ease it down..near 330 mark. Before the front touched I hammered it again to ease the landing. It was different than door slammers jerking a quick wheelie on line and coming back down immediately. Wish had better photos than from phone. For gears,,4.56 now and 14/32 tires. I expect i'll need 3.90-4.10 to keep 7200 rpm,,,at 15mph more in 1/8th. Maybe a 3.73 would be better and gear it for 6200-6400. May require a cam change though. It's comp cam,324IR-10. 286/286,748/714 and 110LSA. Heads are 320cc and flow 388 at 700 if I remember the sheet. The injection is smallish and would favor the lower revs with it's tiny 2 7/16th butterflies.
It is a fun ride,,as a fellow said,,you drive a RED,,you EXPERIANCE a FED. I carry a rag on my lap to wipe my shield after the burnouts so I can see tree clearly.. My new helmet looks like crap with marks on both sides from my head rattling in there,,whole thing covered with specs of rubber and vapors mists each time as the methanol boils out of the oil. Don't know how close Grumpy lives to Lakeland,,but if your able to get in,,I'm fine with a test pass...even if it's only a easy one or half track..it is a cool experience. It drives 100% better with wheelie bar so I'm safe letting others in it.
riv187

 
Posts: 3
Joined: September 26th, 2014, 1:05 pm

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby 87vette81big » September 27th, 2014, 6:41 pm

I love your DIGGER.
Everyone is low on cash $.
Trying to figure out how to go fast & reliable takes Homework.
WELCOME.

Brian R.
87vette81big

User avatar
 
Posts: 3278
Joined: February 28th, 2012, 12:34 am
Location: Central Illinois

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby philly » September 27th, 2014, 10:20 pm

wow welcome to the site and nice car!
-phil

There's never enough money to build it right, but there's always enough to build it twice!
philly

User avatar
 
Posts: 1364
Joined: December 12th, 2013, 4:08 pm
Location: Miami FL

Re: BBC is it really necessary for 4 bolts or stds good enou

Postby Wilson1 » November 22nd, 2014, 9:19 am

I have run two bolt, four bolt, and a Dart block. My 468 is a 2 bolt block that I have been running for years without any issues. If you are going to keep the car in the low 7000 RPM range, you will be fine. BUT - Yes, buy the ARP 2000 rod bolts. Every time you freshen your motor, put new rod bolts in and new roller lifters if you are running a roller cam. Buy good roller lifters, like Crower, make sure you have ARP main studs. Your cam at 748 lift won't kill springs if you use good ones. Always check your spring pressure every year.... The key to running a two bolt stock block is to not go over about .080 on the over bore, I know people will tell you that .100 is safe, but if you don't want to bring your stuff home in a garbage bag stay way on the safe side. After all I assume you are bracket racing. I would have your block sonic tested so you know where you are. I know doing all the little things is a pain, but it will give you many days of trouble free racing.

One main thing about running a BBC in a dragster is the oiling system. I assume you will be running a wet sump. DON'T run a flat dragster pan. You will starve the motor on shut down. Get a good 7" deep sump pan, yes it will fit, that has good baffles. Reher Morrison has the best set up I have ever seen. It is expensive, but I can get on the brakes at 170 with the chute out and never drop below 50 lbs.

If you don't short cut the little things, you will be a much happier camper. Even if you have to run the SBC for another year. Did I mention - Buy the ARP2000 LOL
Wilson1

 
Posts: 14
Joined: November 19th, 2014, 10:33 am




Путь к Счастью! Заработает 320 000 рублей в месяц даже нович

Postby Thomasot » February 24th, 2016, 2:15 am

Даже такой легкий способ, приносит такие большие деньги!
Скачайте курс и забудьте о каких-либо еще вложениях!
Умеете печатать на клавиатуре? ЭТОГО ДОСТАТОЧНО!
Скачайте и зарабатывайте! Все легально, все просто!
Курс - "Путь к счастью". Название говорит само за себя!

Подробности..
Thomasot

User avatar
 
Posts: 997
Joined: December 15th, 2014, 8:46 pm
Location: Россия

Next

Return to Engine: Repairs , Modifications ,trouble shooting and tunning

Who is online

Users browsing this forum: No registered users and 3 guests