70's small block durability mods for 700hp

I know there are some very fast and experienced racers on this board.

What are some of the top things that I can do to a 76' small block 360 to make it more durable without breaking the bank.

Because the bank is already broke with the purchase of below parts:
new heads ($2200)
New 78mm turbo and parts ($840)
New sniper EFI ($1250)
Machining and balance ($??)

I've acquired parts to make more HP than I think the stock block may be able to handle.
Not sure, never been there or done that. Yet.
Goal is 700 or more blown/turboed.
Both if need be.

I do have diamond forged pistons 1/16,1/16 rings
Main studs
Eagle SIR I beam rods (says good to 500hp??)
I will NOT be spinning this thing above 6000 rpms

Someone mentioned a short fill.
Someone else said I need a forged crank.
What about a main girdle?

For those of you who have done it not just hypothesized about it.
What's the STRAIGHT scoop?

Your tune will have to be spot on no detonation

Take those sir rods and heave them over the closest cliff and walk away

I know your one of the guys who has the knowledge to do it.
Any other tips or will it hold up with above parts sands the SIRs?

Before I balance what about these?
It says: 7500rpm/700hp

https://www.ebay.com/itm/291747788433

We finally hurt an engine (408) last year and something hit the block so I'm assuming a rod broke but it's not apart yet for me to see. This was a K1crank and K1 rods with upgraded bolts which I always do. It was rebuilt 3 times and in need of its 4th when my son asked to borrow it and finally let go. I particularly blame running alcohol as it's harder on bearing, bore wear, and other issues.

Do you want to trust imported rod bolts?
ARP makes several different quality and priced rod bolts, all in 7/16 diameter
The #8740 are the cheapest and weakest , their ARP 2000 are better and more expensive and their L19 bolts are the most expensive and strongest for all racing applications with a lot(500+ HP and 7000+ RPM)
The piston total weight and ring pack affect drag and weight, and the RPM they (all components)will fail at
Good luck, buy the best rods, pistons, rings and bearings you can for this build, not the cheapest

From what I know of small blocks isn't headgasket failure and issue with too much boost/compression?
Gus

Current bob weight is calculated at 1932.
I used mopar rod bolts in stock rods for 72k miles
without issue. 5800 rpm redline and 10psi.
RPM will not be over 6k, most likely 5500 so I could use STOCK rod bolts and never have a problem.

Compression strength around the base of the big end on the rod beam is what I need.
Nothing is going to fly apart in this engine. Gonna get smashed or twisted from boost first.
. :-)

$200 H beam rods will be perfect. Or just stick with the stockers. Sounds like you have it figured out.

Head gasket troubles?

I think so.
Maybe this will help.
Maybe not.

Chevy guys make 1000hp to the wheels with a junk yard base.
Lucky dogs.

Its a junkyard base yes but it has been taken apart, the rings have been gapped, the cam has been changed, fastners changed etc. Matts truck is impressive on the dyno for sure and its no slouch on the track but it doesn't spend much time there.

All fasteners and gaskets in his engine are reused against factory recommendations.
Even the "stretchy" head bolts.
Everything is torqued to 65ish lb. ft. or untill it FEELS like
it is about to snap.

Like I said.

Unfare advantage as chevy built this engine using racing technology.
6 bolt skirted block.
Cylinder bores special hardened material that does not get a ridge even after 250k miles.
Crank good to 1000hp reliably.
2nd gen rods good to 900hp.
Heads super high angle factory cast ports with excellent deck thickness.
Shorty ductile Iron headers.
Solid pistons and intake manifold.

Blah. (sticks finger down throat)

Oh well. 60 year old technology vs. a very good LS design. I guess I should be upset that I can't text with my old rotary phone.

It's an apple to orange comparison. Put a rod and piston in a third gen Hemi and give it hell.

While what you really need is a race block, I fully understand the budget issues.

I have cracked cylinder walls on half filled stock blocks with a lot less than 700 hp. However it was with over 16 to 1 compression.

I would fill the block as high as you dare. Its cheap and it will help.

Good luck!
Bill

Definitely do a forged crank, ditch the I beams and get some H beams, Also I would suggest doing the oil cross over line in the lifter valley, tap in-between 8 and 6 lifter valley and 1 and 3 lifter valley, connect them with a I believe 3/8 tubing, have done it on last two motors and it works great, oil doesn't have to travel down the passenger side to the front main up to the drivers side and back, puts oil directly on drivers side and helps aid in oiling to front main bearing, there is actually a really good article on oiling mods somewhere online, I did all I could, drilling out main passages to true 1/2'' and mains from the lifter feed to true 9/32, I was really surprised how small they got once you got 2 inches in, I always run full grove main bearings as well, the way I see it with full grove bearings your rods get oiling all the time, with 1/2 or 3/4 bearings you are restricting oil to rods to timed oil, just like the rocker arms, just a few tricks that could help it live at that power...

The 360 has the largest main bearings of Chrysler OEM V8s. I'd not put $$$ into a forged crank, buy instead a new 9000 Series from SCAT.
Also the SIR rods have been good for the last 4 years or so but I'd replace them with SCAT Pro series. There is no inherent superiority of H-beam over I-beam, and horsepower ratings for connecting rods are bogus from the start. Having said that, the SCAT have several good points, material, 7/16" bolt size, and low weight especially compared to the stock rods.

By keeping rpm low, you are extending the life of the engine.

R.

Ok.
Short block fill is on my list.


I'm having a hard time finding rods to use because of the pistons.

Must be 1.123-1.125 length. (edit 6.xxx)
Must have .927 small end diameter
Can be either 2.125 or 2.10 big end dia.
Must have big end width of .927

Most all I find that would work have a .940-.945 width.
How hard is it for the crank grinder to open up for rod side clearance?

Either that or I buy a mopar sb rod and have the small end bushed.
Is that less expensive?

Scat 9000 cranks are only $300ish.
If I bought one of those it would be a 4" stroke and I would have to throw everything else out the window. LOL

Boost will be my cubes. :-)

I'm thinking it is a lot easier to narrow the rod big ends than widen the crankshaft rod journals

First of all I have to say, depending on a used stock crank at 700hp is foolish.

Now how's it going to add up? 9.600 block, 3.58 stroke, 6.125 rods means the pistons have to be about 1.685 compression height. You said "Must be 1.123-1.125 length" which I don't understand. 4" bore pistons with a chevy pin size and 1.685 compression distance are not falling out of any trees. They're custom

a 350 chevy with 3.75 stroke and 6.000 rods needs a piston with compression height of 1.12, is that where that number came from?

Anyway, I agree with Cab that trimming the rods' big ends sounds like the right way to go.

The block can use every trick you can give it. Girdle, short fill, etc.

Good Luck!
R.

Oops, 6.123 - 6.125

14ish years ago I bought diamond forged dished pistons for use with magnum heads, chevy 6.125" eagle rods and stock stroke crank.

Most here are telling me to throw the rods I have in the trash.
For some reason these eagle SIR rods have small pin size and also have the stock width of a sbm.

First thing I would do is measure the crown thickness of the dished Diamonds you have. If they started life as a regular flat top, and were milled to get the compression down... they could be thin and not suitable for the power you're talking about...

Ask me how I know...

IMG_20140104_121106_840 (1280x720)

I think 700 HP is going to detonate your bottom end... you can try a stud girdle that may be some insurance. It might stay together with only an occasional blast down the hwy but won't last under any serious boost over 7-8 lbs. Mopar cranks are strong but they have their limits.

My 13.5-1 SBM has been o-ringed. Used Fel-pro gaskets.

Big end width is not a big concern to me. A bit narrower won't hurt anything. Stock rods will last at 6500 rpm's. My oval track motor tossed a rod when the former driver ran it with thick oil and no engine warm-up...

You can bush the small end of a stock rod... finding a shop that will work on this may be a little tuff... so many only want to do belly button engines and are afraid to bend the rules.

As mentioned before... mine is a girdled 1991 360 block, 1/2 fill, with a stock cast crank, h-beams, and custom diamond pistons. Non-intercooled on E85 I've run mine at 23psi. From the ET/MPH/Weight, that is somewhere in the 850hp neighborhood at the crank when it's turned up that high. Most of the time I run it around 9.90 which is 700~750hp range since it doesn't have a cage in it.

I made around 700hp on stock rods, before putting the h-beams in it. That was with a pretty small cam though, and never went over 6K. I've heard lots of bad stories about SIR's, but never seen one break myself.

If you can't afford to replace the parts it's going to kill if it breaks a rod... better to save up for something better now then be disappointed later.

I would say if you're going for big power that you'd want to put a girdle on it. I know that you could see really strange things on the main bearings, where the main caps were moving around a lot. The girdle definitely helped that situation.

The tune needs to be pretty good to make big power without hurting stuff.

As this is your first turbo build, you should expect to break some stuff along the way if you're going to shoot for big power (especially with low-buck parts). Just make sure you're prepared financially, mentally, and have the time to go through that WHEN it happens.

The small block is a real good platform to build 600hp out of pretty easily. 700+ is pushing it, and going to get expensive unless you have a very good handle on tuning it.

How would a person measure the piston top thickness?
Ramblings on a few things.
Stock rods look bulkier.


Old combo.
#7 was blowing air out into the crankcase when pulled apart.
Cam specs were 505/515 lift 224/230@50 110lsa
2.02 valve with 75degree deep bowl cut.
Silv-o-lite pistons blah blah

A note on the half fill, I was looking into it pretty deeply for my build (also same goals, 650-700hp for a street car while attempting to keep the RPM's low only I'm using a blower instead of a turbo).

Hughes told me don't bother with it.
My machinist, a very knowlegable NHRA super stock record holder said don't bother and stated there was plenty of meat in the lower bores of my 340 block. I had actually paid him for it and he called me up asking if I wanted a refund telling me he didn't think it would provide any benefit.
I have also talked to a few people making 600-700hp with lower rpm forced induction builds who did not half fill and had zero issues.

There were, of course, a lot of guys that I found who DID half fill and had SBM's living at 650+HP. I'm still on the fence on whether or not I did the right thing by not doing it, but I do know that it probably saved me from some potential oil temp issues.

I just don't think I've seen anyone yet who had a high HP, low RPM forced induction SBM fail because of issues that could be attributed to lower bore distortion or anything that a half fill could have prevented. I've never seen anyone talk about problems they had with a turbo/blower motor that were solved with a half fill.

Did you use a girdle? What about all the others you talk about?

I'm pretty confident in the block, crank, and pistons.

2 bolt mains make me think I need a girdle because you don't have the same clamping force as 4 or 6 bolt blocks but not sure if they really help on a sbm. I've read on here otherwise.

The rods I have unless they are made of some seriously good material seem sketchy. But who has actually seen them fail in a low rpm engine?

I know the LS guys are bending the piss out of their skinnier rods at 700hp+

I did use the girdle with mine, most of the guys I talked to making 600+hp used one.

I have heard some debate of whether or not a girdle that doesn't tie into the pan rails actually helps, but I've spoken to a few well known engine builders who say it definitely does and also have talked to guys with first hand experience using them on mopars or other brand motors where the girdles mount the same way who have fixed or at least greatly improved bearing wear issues they were having as a result of cap walk.

Many of the guys who told me it it was just a gimmick on a motor that doesn't have the girdle tie into the pan rails had no first hand experience to back up their claim, so I decided to go for it.


I have heard some good cases made for using billet caps, and if I had an unlimited budget but for some reason needed to stick to an LA block I probably would have used them. The reason I used an LA block was because I didn't have an unlimited budget though, and with the cost of buying billet caps/having the block machined for them I would have just gone R block.

I tossed the Eagle I beams I had in my 340 and went with Eagle H beams and ARP2000 bolts.

Thanks for your input 1mean340.

I've been in contact with SD-Concepts in RI and will see what they have to say.

Looking at these as next choice unless they say differently.

https://www.ebay.com/itm/331624224300

I also see this for sale:

https://www.ebay.com/itm/371660576728

I'm reading the book
MOPAR SMALL BLOCK HOW TO BUILD MAX PERFORMANCE
After skimming through and then reading up to the rod selection section it appears I will learn very little.
Not much new and less technical than the original How to hotrod small block mopars I read back in the early 90's.
A little disappointed actually.
Maybe I'm just dense.

Demand a refund!

You might go to www.moparchat.com & scroll down to & click on "circle track chat" & then read thru Sanborns' oiling/cooling mods that are in a sticky at the top of the page. it'll take you a good hour at least. definitely worth it.

Ok, I read the oiling mods link.
8k rpms is outa my league.
Also just finished reading this book @ 6am this morning.
I learned a couple things about auxiliary injection systems for cooling intake charge.
Back to the basics by Larry Shepard.

I'm putting my 383 SBM back together with 340 rods... it's had them in there for two seasons @ 575 HP and they work well unless you spin a rod bearing and keep the hammer down...

O-ringed the deck and use a copper head gasket along with good fasteners. The rest you've been already told. A spot on tune will definitely be needed.
My mostly stock 318 went from 160hp on the Dyno to 536hp on back to back pulls. Stock 2bbl and exhaust to GT45 turbo and a 800 cfm Thermoquads using C 12. The only failure was the head gasket. I O-ringed the deck and installed copper head gaskets it has held up to 26lbs. of boost at the intake.
If it See's detonation at those power levels bring a shovel and a bag. Dave

My 383 used o-rings and old style steel shim gaskets with 13.5-1 on methanol... todays MLS gaskets are pretty good.

Thanks for all the opinions and experiences shared.
Just finished reading this book.
It had a decent section on durability mods.
Really enjoyed the history of turbos section.

Charmed life of a boosted engine.
Via Supercharging performance handbook circa 2016

15psi of forced induction creates ONLY a 8% increase in rod compression forces.

6k to 7k rpm jump using standard N/A tricks to produce more HP increases rod bolt/rod forces by 36%

That is true...if and only if you have enough octane, no detonation, and the timing backed WAAAAAAAY down.

There is a reason people run o ringed blocks and cometic gaskets, and I assure you it's not only for that 8%!

707hp N/A

Look closely,
Stock Block, almost Zero oiling mods.
2 Main BOLTS per cap, NO studs.

http://www.hotrod.com/articles/small-block-big-punch/

Why you didn't show me some vids of that beast?
lol
The in car 9sec pass is insane!!!!!

Dizuster

What happen with the kit idea?

https://www.theturboforums.com/threads/who-wants-a-mopar-turbo-kit.376862/page-2

What are you doing for trans, converter, drivshaft, and differential ??
My car will only be about 100# lighter than yours.

I have a dynamic converter but 727 needs rebuilt as I think the pump went out.
It had been hack job manual shift converted and ran full line pressure at all times.

A guy w/ a nice SB Dart at the track talked to me about how Herb McCandless had stressed to him that the stock-ish oil system on his car needed some upgrades (baffled pan and I don't recall what else) to keep the bottom end happy.

If you haven't already given some serious thought to that, I'd say now's the right time. The other guy didn't take Herb too seriously at the time, and then told me later how he hurt the bottom end just like ol' Herb warned him would happen.

Hey, sometimes even free advice can actually have some value...

Yes sir,
I will heed your warning.
From reading up on some oiling mods the first thing that popped out to me is the pickup size (low pressure/suction side) and your right.
Keeping the pickup covered too.

I will weld in baffle and flair the sides of the pan while I'm at it.

After making the vid and showing my front 2 mains were worn through to the copper I originally thought it was the supercharger tugging on the crank.

After reading the oiling mods thread on moparchat I now think those front two were getting less oil than the rest.

I've decided to go e85 on this thing too so I'll have a safety barrier for detonation.
Most likely chunk the aftercooler in the corner though.

Keep the intercooler and get the jetting correct for that
You can't get the fuel air inlet temps to cold, ever

The intercooler I have is a Procharger 3" that has a 700hp rating.
I figured with e85 it would cause a couple (at least) psi drop being my goal is 750ish hp.

I also thought that the high octane e85 would not require any intercooler at all for the low boost levels I'll be running to meet my power levels. 12-18psi.

Hmmmmmmmmm

Re-reading this thread again for tidbits and just noticed you said THERMOQUAD.
Do you mind expounding on the mods that were required to run boost?
I have one in the big bore version on the shelf.

E85 doesnt need to be intercooled. Thats plenty of octane for enough boost to make 750hp.

The thermoquad setup hes referig to was an old draw through style. Youll need a good e85 blow thru carb for what your doing.

I've decided to back up on the e85 idea for a bit.

I already have a blow through carb and the cost of getting it converted, upgrading the fuel lines, and buying a new pump that can handle the added 25% increase in volume is kinda pricey.

Here is the pump I'm using but with a total of 22psi (7 base +15psi boost) it's flow is limited

http://www.usrallyteam.com/content/products/fuelpump/sx_18203.pdf

I'm planning to go 93 and Meth injection to start.

Tuning school vid says that e85 AND meth is the best of the best so if I get the meth kit now I can go e85 later and have the best of both worlds.

This is the kit I'm going to get IF they will ever send me an invoice or link to buy it.

http://www.airfuelinnovations.com/documents/AFI_MethTool.pdf

Those guys are so busy it's crazy.
They are overflowing with business it appears.
Must be doing something right.

Did you ever make any manifolds for turbo kits?
Any extras lying around? $$ lol
Trans tips for my 727?

Does effective volume mean the piston has a 34cc dish?
Or does it include how far the piston ring is down the piston too?
Maybe even total volume with standard deck height block?
Does this calculation look right?
Seems kinda low at 7.66 to 1.

Yep I ran it on a draw though setup. I went to a blowthrough and still tried the Thermoquad but above 18lbs boost the plastic float bowl blew out.( In a box it probably would work well.) Went to a Edelbrock 600 and that carb has worked well with minor mods.

You need to do some block work to increase volume, Message me if you have any questions.