ez2cdave

I've been using the Search feature and Googling, but have either been seeing "ancient" threads or conflicting information ... So, I have a few questions

Application: 1989 Camaro RS (Full Stock Weight w/AC, etc) ... 99% Street Driven, EVERY day.

I'm debating a 383 vs. a 400, using a DART SHP Block (4.030" or 4.125" bore) and am researching Rod Length, Pistons, & Compression Height . . . These are what I'm looking at so far.

383

(1) 4.030" Bore ... 3.75" Stroke ... 5.7" Rods ... 1.433" Compression Height.

(2) 4.030" Bore ... 3.75" Stroke ... 5.85" Rods ... 1.250" Compression Height.

400/406

(1) 4.125" Bore ... 3.75" Stroke ... 5.7" Rods ... 1.433" Compression Height.

(2) 4.125" Bore ... 3.75" Stroke ... 5.85" Rods ... 1.250" Compression Height.

Are 6.00" Rods possible, while still maintaining a minimum 1.250" Compression Height without going to an expensive Tall Deck, Raised Cam block ? From what I have seen, so far, it doesn't appear to be . . . The closest I can get seems to be a 1.15" Compression Height and I want to stay out of the Oil Ring land, if I can.

I found a few interesting links along the way:

http://www.stahlheaders.com/Lit_Rod%20Length.htm

http://www.rustpuppy.org/rodstudy.htm

http://victorylibrary.com/mopar/rod-tech-c.htm

http://victorylibrary.com/mopar/cam-tech-c.htm

http://www.strokerengine.com/RodStroke.html



Thanks, in advance, for you help and suggestions !

sofakingdom

iTrader: (1)

A block is always the same "height", which is, the distance from crank center to deck surface. ALL stock SBC blocks are 9.025" nominal in this dimension. The tolerance is roughly -0.000" +0.025" on that.

ALL stock SBC rotating assemblies are nominally 9.000" in "height"; which for those, is ½ the stroke, plus the rod length (center-to-center), plus the piston compression height.

Ideally, in a perfect world (you know, that universe we all love to imagine, in which there are no hypothetical situations) the block height and rot assy height would be identical. If that's true, then the piston comes up to EXACTLY co-planar with the deck at TDC. However, in the real world, that extra block height results in "deck clearance"; and those of us who pay attention to details like this and therefore our motors built out of the EXACT SAME parts list as everybody else's will STOMP theirs, get the block "zero decked" to the rot assy height, to eliminate that clearance.

So for example a stock 350 has a 3.48" stroke; half of that is 1.74"; rod length is 5.700"; piston compression height is 1.560"; add em up, you get 9.000". Likewise, a 400 has a 3.75" stroke, so half of that is 1.875"; its stock rod is 5.565"; and its stock piston has 1.56" compression height. Once again, 9.000".

So to answer your question, 9.000" - 1.875" = 7.125"; 7.125" - 6.000" = 1.125", which is the maximum possible piston compression height. Any taller than that, it will come out the top of the bore.

Not too tough really. Not even "math". Just some addition and subtraction. A 2nd grader should be able to work all this out without touching their eraser. Even I can handle it; and if I, the stooopidest blob of protoplasm to ever splat onto the face of this miserable planet in all its history( just ask my kids) can handle it, surely all you smart people out there can too.

ez2cdave

OK, what about 5.7" vs 5.85" rods ?

I What is the MINIMUM Compression Height, without putting the Wrist Pin into the Oil Ring land or positioning the rings too close to the top of the piston? I am looking for longevity here.

Also, I called Dart and found out that BOTH their 350 and 400 SHP blocks have Siamesed Bores, WITHOUT Steam Holes . . . Is this an issue, since the regular GM 400 SBC block has Steam Holes ?

I am going to be using AFR 195 heads.

articwhiteZ

iTrader: (56)

ya don't need them.. with the dart block
and why would you go so small with a aftermarket block anyway?

no Replacement for Displacement!

ez2cdave

Traction will be a problem either way ( 383 or 400 ). I briefly toyed with the idea of a 427 with 6" rods, but dismissed it when I realized the situation about the Wrist Pin location.

Now, this would not be a problem with DART's 9.325" Tall Deck block ( 4.125" Bore, 4" Stroke and 1.250" Compression Height ), BUT I am not spending $2800 just for the BLOCK on a street engine!

I wouldn't exactly call stepping up from a 170 HP TBI 305 to a 425-475 HP motor (Carbed) "small". My application is 99% Street-Driven, 40-50 miles, EVERY day, 5 days a week, plus weekend driving. There will be lots of "stop & go", plus idling in traffic, with the AC going full-blast.

I chose to avoid the "stock" GM block for reliability issues, especially with the 400 engine. Plus, I have the ability to "step it up" later, if desired, since the internals will be 4340 forged crank & H-beam rods, with forged flat-top pistons (10:1 CR +/- with the AFR 195 75cc chamber). A cam change and, possibly, heads and intake would make that simple to do.

ez2cdave

Anybody have any input about 5.7" vs. 5.85" rods ?

vetteoz

iTrader: (13)

For which block ?
http://www.iskycams.com/techtips.html#2005

The 5.85" seem popular for big cube (420 + ) SBC's
http://www.chevytalk.org/fusionbb/sh...hp?tid/150334/

sofakingdom

iTrader: (1)

OK, what about them?

I'll answer that question with another question:

What is the MINIMUM amount of life insurance you should have? This situation is not too different from that, in a lot of ways.

But, take a look at THE NUMBERS. They, at least, don't lie; even if they don't always contain the answer either.

GM thought that 1.56" was the minimum; otherwise they wouldn't have had to use the long piston and therefore the short rod in the 400. Of course, not all of us are THAT conservative and risk-averse; but FWIW.

http://www.jepistons.com/TechCorner/...rminology.aspx

The top ring is around 3/16" down from the piston crown; the upper 2 rings are about 1/16 - 5/64" thick and the oil ring is about 3/16" thick and there's about 1/8" between them, and the oil ring needs about 3/16" min below it. So that's .1875" at the top, a total of .375" or a little more worth of rings, another .250" between them, and .1875" at the bottom... right close to 1" total "height" of the ring package. The pin is .927" dia; half of that is .4635; add that to the ring package, you come up with 1.4635", approximately.

Anything less than that 1.46" or so, and you have to either (1) locate the rings closer to the piston crown, (2) make the rings narrower, (3) pack them closer together, (4) leave less space between the bottom of the ring lands and the top of the skirt, (5) move the pin up into the rings, or (6) use shorter rods. Or of course some combination thereof.

Pick your poison.

Think about what happens if the pin bore gets up high enough to get behind the rings. Since the first one it will encroach on is the oil ring, how much difference does it make, if it's there? Really? As long as the top of the bore doesn't go all the way to the top of the ring land, does it really prevent the oil ring from scraping oil off the cyl walls? Probably not... but, the ring could bend away from the upper surface of the land. So for that, there are ring support spacers available from the mfrs of the better pistons, that you put into the pin bore, and they sort of "complete" the oil ring groove.

There's no "one" "right" answer to your question; as if, if the compression height is .000001" less than whatever the "magic number" is said to be, the matter will meet the anti-matter and annihilate the entire known universe into a black hole. It's all about, how likely do you think you are to "need" any of it at all, and what level of risk or whatever, are you willing to tolerate. Kinda like life insurance.

As to the motor size, it doesn't make awholehelluvalotta sense to spend $2000 on a block, and then cheeeeeeeeeeez out on what goes inside it, eh? You'll find that, to a point, all displacements cost the same; might as well get as much as your money will buy. That's what the "small" comment is about. Although, with 195cc ports, you're basically using 350 heads, so even a 400 is going to be somewhat strangled, if this is going to be anything beyond a street motor.

Personally, having run 400s in a bunch of my cars over periods of many decades, in sizes up to 434 CID, I find the "reliability" complaints that come predominantly from people who have never had one, VASTLY overblown. From your description of what you want to do, I don't see a need for a $$$aftermarket$$$ block just yet. But that's just me. I think you'd do better to spend you cubic bucks some other way, unless you're one of those lucky folks that has a more or less "unlimited" budget. That's a nice block and all, just, ALOT of money for something that won't make much difference to the outcome of the finished product.

Frankly, for a relative n00b builder and a street motor, I'd suggest just yerbasic stock 400, except with an aftermarket forged crank and 5.7" cap-screw rods; rods like that aren't too much $$$, and that's a pretty common piston. They're long enough to permit internal balance which IMO is THE MAIN reason for using a longer rod anyway. All the Internet hooey about "rod ratio" really only applies to people who have maxed out EVERY OTHER DETAIL of their build, and they are comparing 2 otherwise identical motors side-by-side; in that kind of case, then yeah, the longer rod has a slight advantage in power etc. For a street motor that doesn't have that degree of effort behind it, the longer rod doesn't make a hill of beans worth of difference, once you get it long enough to permit internal balancing.

ez2cdave

I am asking if there is any worthwhile advantage to running a 5.85" rod vs. a 5.7" rod, in either a 383 or a 400 .

In a 383 there is an advantage to running a 5.7" 350 rod, over the 5.565" 400 rod. I am wondering if there would be further advantage to running the 5.85" rod in a 383 or 400, over the 5.7" rod and what, if any, "trade-offs" would result from doing so.

ez2cdave

What is your source of information that GM chose to use the "minimum" compression height and that the figure was 1.56" ? How does the stock 350's and other SBC's "factory" compression heights compare ?

Your explanation of Compression Height and the link to the diagrams was very helpful. Thanks !

Orr89RocZ

iTrader: (20)

Too short a rod will induce lots of side thrust against the bore. Stay away from 5.56 400 rods. 5.7 is ok with a stroker but 6" is easier to balance.

There is no big issue with a 1.125" comp height with modern ring packages and proper machine work and break in process.

I run 6" rod 1.125" dish pistons in my 800 hp soon to be 1000 twin turbo motor

ez2cdave

My main concern is longevity between rebuilds and reliable daily-driving. This car will probably be driven around 10,000 mile per year, in "stop & go" trafic, with some highway miles.

As it looks now, it might be that a 383 might be a better choice, over a 400 in my application. I had planned on using the AFR 195 Eliminator "Competition" heads(CNC ported), but the other guy said they might be too small for a 400. My maximum revs will be 6000 RPM +/-.

Personally, I think they would be OK, especially since they are available with a 75cc chamber that would give me 10:1 with flat-top pistons in a 400. They are part # AFR-1094 in the Summit catalog.

http://www.summitracing.com/parts/afr-1094

I also had my eyes on THIS, but was worried about the Compression Height.

http://www.summitracing.com/parts/drt-03124272

Thoughts ???

Thanks !

AlkyIROC

The biggest advantage to using a longer rod is that it moves the wrist pin higher up in the piston. This means the piston isn't as tall and can be made lighter. Lightweight pistons are desired for high rpm engines because it reduces the bob weight on the crankshaft. A longer rod also increases the piston dwell time at the top and bottom of the stroke but in most applications, this means nothing. I spun a short rod 383 to 7000 rpm and ran high 11's until a stock rod bolt failed and took out the engine.

The disadvantage of using a longer rod is that the wrist pin starts to get close to the ring grooves. You can't move the wrist pin into the top 2 grooves but it works fine in the bottom oil scraper groove. To keep the wrist pin out of the compression rings, a taller deck block is used when using a longer rod.

ez2cdave

Thanks for the info ! I knew about the wrist pin situation. If the wrist pin is in the Oil Ring groove, how does that affect longevity and durability in a motor?

sofakingdom

iTrader: (1)

The compression height of the 350 was 1.56".
The compression height of the 400 was 1.56".

When they invented the 400, they had the choice of doing one of 2 things: EITHER they (1) left the rod length long enough to permit internal balancing, by REDUCING the compression height; OR (2) they left the compression height were it was, and reduced the rod length, EVEN THOUGH it entailed the painful consequences of external balance (cost, dollars, money, $$$$, overhead, labor, more inventory, different part #s, $$$, ... stuff like that, that companies like GM don't take lightly).

We all know what they did.

Now I freely admit, I'm not the brightest crayon in the shed; but.... whaddya think? what did GM engineers think the compression height should be? what "source" do you need, beyond A MICROMETER?

Side loading on the bore is a total non-issue for a street motor. Becomes an issue when you want to push the power-output envelope; but otherwise, no. That's not why you use a longer rod in a street motor. You use a longer rod so you can internally balance the motor. Twin turbo motors on the strip 12 seconds at a time, one thing; drive to work in the morning, stop & go, idling around town, AC on, ... yeah.

That's only about $5000 or $6000 or so, before shipping and machine (prep) work ahd assembly and all that; no big deal. Go for it.

What heads have you ACTUALLY got?

What are you REALLY going to do with this motor?

What is REALLY your goal here?

What REALLY is your budget? (backed up of course by a bank account balance, just to keep it honest)

Pie-in-the-sky, and a bunch of theoretical rod length stuff is fine; but at some point, ya gotta whup out the credit card and start turning bolts. What are you REALLY going to be looking at, at that point?

Anywhere between NONE WHATSOEVER and ABSOLUTELY CRITICAL, depending on the answers to those other questions. How much life insurance do you "need"?

sofakingdom

iTrader: (1)

I would add to this, that it's SOMETIMES true; but OTHER TIMES, the weight of the added rod length, weighs MORE THAN the weight you lose from the reduced piston height. Quite often in fact; more often than one might think. Last one I ran across was using some KB pistons and either Eagle or Scat rods; just some real typical, open-the-box-and-bolt-it-up kind of combo that you can readily buy already pre-packaged at a favorable price from the crank & rod mfr as an "assembly". The long rod combo had MORE reciprocating weight than the shorter rod combo.

Like life insurance, there's no "one size fits all" answer to that. Ya gotta answer all those OTHER boring questions about all that flooby-dust stuff like "goal" and "budget" and "risk" before you can get at "the final answer" to stuff like "rod length". You can't just start in the middle and work your way back toward the beginning and forward toward the end at the same time.

Orr89RocZ

iTrader: (20)

Sounds like you definately arent pushing high performance with 10k miles a year type daily driving. Sub 6k rpms, a afr 195 will work fine. I ran that combo and was all done by 5800 but very torquey. Another friend ran them on a 408 and was done by 6100. Cam and intake will determine alot of that but overall those heads are good for those cubes to 5500-6000. Good street rpm.

If 400, examine piston choices for adequate street comp. 5.7-5.85 rod will work fine, if not a high performance build. Rings should end up out of the wrist pin and last long time as long as rings are properly set, cylinders are bored true and have proper finish to allow rings to set and seal. Machine work and clearances are critical

ez2cdave

I'm 52 years young and no stranger to cars, but I have no experience with stroker motors and very little with small blocks, at all. Your "tone" comes across as "condescending", but the Internet is a "funny" place and typed words don't always convey the emotion behind them, accurately.

My last "car", 25 years ago, was a 1970 Chevelle with an oval-port 454 (about 545 HP ), Turbo 400 with a 3500 stall conveter, and a 12 Bolt with 4.11 gears. I owned it from 1981 to 1988 and I drove it on the street at 6 mpg, taking it easy, (Yes, I street-raced LOL !) and ran it on the strip on Saturday nights. I used to run at Miami-Hollywood Speedway in Ft. Lauderdale, FL ( I think they closed it a few years back ). It ran 11.70's at 112 mph on slicks ... I think it was about 3800 +/- lb. with driver.

To answer your questions:

(1) Heads will be purchased when I make a decision on the motor combination.

(2) I intend to street drive this motor, just as I have said, do a little "stoplight to stoplight", and occasionally run it on the strip.

(3) I'd like to see easy mid-12's or quicker, as long as I can stay above mid-11's, since I don't want a roll bar in the car. I don't want to have an "un-streetable" combination that is a PITA in daily driving. Hence, my interest in strokers and possibly that 427 to have a milder camshaft setup.

(4) The overall "budget" is around $15,000 +/-, as follows: (Realistically, it might reach $20,000, but I doubt it )

$9000 +/- for the motor
$2500 for the Strange S60 rear end.
$1500 +/- for Suspension Mods ( LCA's, SFC's, Torque Arm / DSL, Panhard Rod, etc)
$500 for the Strange Chrome Moly Driveshaft (1350 U-joints)
I still have three TH-400's from the Chevelle. I will probably use one at first, but I'm thinking 4L80E, down the road, or putting an overdive unit on the TH-400.
$1500 - Miscellaneous ( Ignition, Exhaust, etc )

My son in law is part owner of an automotive machine shop, so that cost should be CHEAP . . . At least it BETTER be - LOL !

That assembled and balanced DART 427 short block looks like a good deal to me and would save money on assembly, machine work, and balancing ! Truck Freight runs about $180 +/- for the short block.

I'll either be installing the parts myself or my son in law will be helping me out.

So, THAT is what I am REALLY thinking . . .

1gary

Let's look at this way:

http://www.crankshaftcoalition.com/wiki/Quench

Why??. Because by doing it right is going to help you from building a turd.

1gary

BTW Sofa.Com-on,"be nice".

ez2cdave

Thanks for the link . . . reading about Dynamic Compression Ratio . . . Great info !

1gary

Try this out........

http://www.crankshaftcoalition.com/w..._compatibility

Orr89RocZ

iTrader: (20)

By all means comsider 400 if doing a shp block. Cost is exact same, get the cubes! Mild 230 deg hyd roller and afr 210 head will make 500-525 hp and near that in torque, be streetable and run mid high 11's near sea level to 1500 ft da's in a 3450 lb race weight, typical of a thirdgen.

AlkyIROC

I run 0.250" longer rods in my BBC. The wrist pin is in the oil rings and has no effect on performance especially since I have racing pistons. As for rod weight, the 1/4" longer rods will weigh more than regular length rods but when I swapped from Eagle H-beam rods to Howards billet I-beam rods, I shaved some weight off the rotating assembly and added a bunch of strength with the billet rods.

Also when I went from a piston for my 540 engine to a larger piston to make a 588, the bigger pistons were lighter because of the design so I shaved even more weight off when I increased the displacement. My pistons also have the biggest dome possible to get maximum compression but the underside of the domes are hollow to reduce the extra weight. My 588 pistons have a compression height of 1.060" and they're a gas ported piston.

ez2cdave

Will do . . . A lot of information to absorb !

Thanks !

1gary

As far as the long rod debate...........well LPE started with a 5.7,then a 5.85 and now 6' or more.If you look back to the days of Smokey who said to put the longest damm rod you can fit to the current times where it is common place for builders and OEM manufactures designs that are making engines with longer rods,there has to be something to it.I too don't like ring spacers,but honestly I have seen high mileage engines using the spacers with no problems.

ez2cdave

Since you mentioned LPE, I sure miss John Lingenfelter . . . Another "pioneer".

The links you gave me are VERY informative. I found out that I "got it right" on my Chevelle, without realizing it - LOL ! It was a +.030" 454 with 10.5 CR, running a Lunati Street Master cam with 235 degrees @ .050" . . . They still make that cam, I think . . . Pulls hard.

ez2cdave

If this was strictly a race engine, I wouldn't be too concerned about the wrist pin location but, since this is a true "daily driver" and not even a "weekend toy", longevity and reliability are paramount !

I don't want a motor that I have to rebuild every couple of years.

1gary

The question of a 383 VS a 406 is answered by we have found the 383's walls to be more stable over long periods of time.
The question of 5.7 VS 6.0 rods is answered by the fact a 6.0 rod isn't that far out of the norm.In fact LPE has been using 6.0 rods for yrs and gives a 3 yr warranty on their engines speaks volumes to the positive outcome of 6" rods.Also Howards stopped selling 5.7 stroker cranks by themselves mainly because of how the 6" rods helps prevent rocking of the pistons where they found a number of customer complaints about 5.7 rods and bore/piston wear.

ez2cdave

I assume that comparison was done using GM "factory" 350 & 400 SBC blocks, right ?

Do you think that would still hold true in an aftermarket block, like the DART SHP ?

Orr89RocZ

iTrader: (20)

No, Dart SHP has thicker walls than factory 400's from what I was told by the machinist who did my block. So if you did a Dart 400, it would likely live longer than a factory block.

ez2cdave

The SHP blocks all have siamesed bores, whether the 350 or 400 version . . . I'm curious how they manage to get away without the steam holes of the GM block ?

1gary

Thicker walls on the SHP and thicker decks as well. The issue with OEM 400's is thin walls and decks where the bores do and will move around alot.Either one I suggest with the pistons in the machinist hands final bore sizes using deck plates.We have used OEM 400 in 9.90 race cars,but we do use deck plates and block filler before any machine work gets done and before that we have the OEM blocks sonic and mag checked.

ez2cdave

Yes, deck plates should be used on any engine, in my opinion. Of course, Block Filler is not a "street-motor" item - LOL !

I've been reading a lot at the previous links you provided. It's fascinating and a real education for me !

One thing I would like to learn about is how to predict what relative effect engine displacement has on camshaft specifications. Naturally, I know that the same camshaft becomes "progressively milder" as displacement increases, but I 'd like to see formulas, tables, etc. that can accurately predict the actual effect.

Do you, or anyone else, know of any links to that kind of information ?

Thanks, in advance !

Orr89RocZ

iTrader: (20)

Its pretty simple really. More cubes is more volume per cylinder. More volume requires more time to fill cylinders, so more duration and lift are generally required to increase valve lift curve area to pass the requried flow for a given rpm. Also you can use a larger valve and large head port size to increase area to pass flow through.

Good rule of thumb is 52% of bore diameter for valve size. Programs like PipeMax can be used to determine minimum required (recommended) port areas for the head port.

So a cam with a 224 deg lobe can fill a 350's cylinder up to a peak rpm of 5500-5800 lets say, depending on lift and port size. For that same rpm range, a 400's larger cylinder would not get full with the same duration 224 deg lobe. It may not even get full with the same head port as the 350 motor, even with a large cam.

Its just filling a set volume. General rules are larger valve and larger ports for a larger cube motor, and with that generally larger duration cams for the same given rpm ranges. But not always. A better head port could peak at a given rpm with a smaller cam than say a poor head port with a large cam. Poor head ports require larger cams to make same power and/or rpm as a better head. I've seen general rules posted like for every 30 cubic inches you add, you can add 5-8 deg duration for the same rpm hp peaks. So a 350 with a 224 cam would act like a 383 with a 230-ish cam as far as RPM range goes. Thats pretty accurate given similar lobe profiles IMO. A 224 .600" lobe however may make a power curve somewhat similar to a 230 .500" cam due to the extra lift area. All depends. LSA can also have effects due to changes in overlap.

It can be complicated. Cam designers have the detailed math and sizing programs for their designs. If you had a hard time picking something, its best to call a reputable grinder and talk it over.

1gary

There is a chart in the link Compression ratio vs cam.

Take the terms on a cam card and learn what each term means and how it works.That is what I suggest you do.

A matched parts build is one that takes into consideration the big picture build and may not be the biggest build............................

ez2cdave

Thanks for the info . . . I was hoping for a "plug & play program to simulate the changes.

Orr89RocZ

iTrader: (20)

also visit speedtalk.com and look at posts done by CamKing aka Mike Jones. Good information there.

ez2cdave

I joined SpeedTalk ... They get extremely technical, way over my head. I'm going to scour the website to see what I can find. Thanks !

bwiencek

Personally - since you're daily driving 10-15k a year - and have a goal of decent enough street manners (and I'm going go guess fuel mileage) I'd stick with a 5.7" rod 383 or if you go aftermarket block - a 5.7 rod 400 and set it up with good heads that will make power in the 2200-6k RPM range and shoot for a ton of torque and it'll be a lot of fun on the street from stoplight to stoplight...

I think you've been pointed in the right directions: Pay attention to quench and the DCR for a great pump gas engine, and don't build for max hp at peak rpm but choose parts that are probably "smaller" than you would choose for racing or a max effort engine...

1gary

Excellent post bud.x2.

mmadden55

Longer rods make more torgue and have better angles particularly on stroker engines, all of which is more important than wrist pin height.

TTOP350

iTrader: (8)

I'm running a 6" rod in my 400 stroker, solid roller, AFR 245s mini ram and a lot of hard higher rpm driving (7500-8k).

ez2cdave

On a "race only" motor or where it get frequent rebuilds or "freshening", I agree, BUT what about a 99% Street-Driven car that will see 10-15k miles per year in "stop & go" driving with some freeway miles, too ?

I'd like to see 5 years or more between rebuilds, if possible. Money doesn't grow on trees at my house.

ez2cdave

Do you drive your car on the street ? How many miles per year ?

Orr89RocZ

iTrader: (20)

If you have good ring seal from proper machining and clearances, you shouldnt have a problem with longevity. Oil ring will have a support ring when it goes thru the wrist pin. Its rigid and seals fine. My motor hasnt seen mileage but alot of wot abuse over 3-4 years. On tear down everything looks clean and great as expected. Never had an oil consumption issue as far as i could tell. Leaks were another story lol but wrist pin oil ring wasnt a huge concern imo

But take a look at some modern engines, like ls vehicles. They do not have oil rings in the wrist pin but still have somewhat short compression heights, long rods and thin ring packages which last for 200,000+ miles with good maintenance.

So consider the longest rod possible that you can find a piston for. Attempt to stay out of the wrist pin but dont be too alarmed if its in there. Just run the support rails

TTOP350

iTrader: (8)

You bet I do, as many as I can!
The car has 240,000 on it and this motor has been in for almost 8K miles.

bwiencek

Just a point of reference - on "the other brand" stroker combo that had the pin through the oil ring land location and a ring support under the oil ring - it started using oil in the high 40's and by 58k was using quite a bit of oil... of course this was quite a while ago but from my experience I would avoid it. I've built several chevy 383 strokers for the street with 5.7 rods and never had one use oil (but then again sold most of them before they could get really high miles on them). I know one guy that had over 150k on his 383 in a pickup (it's a mild ~9:1 build with a 'small' 268* flat tappet cam and I think 2.02 double-hump heads so nothing radical)

For the "99% street driven" I would do a short block with a good cast crank, 5.7" I-beam rods (or reconditioned stock ones) hypereutectic flat-top pistons ~.005" in the hole (tighter clearances than forged, stronger than cast), 'standard' .039-042" compressed head gaskets and a cam in the 26x-low 27x duration range to get dynamic compression into the 8-8.25:1 range. (Don't know what heads you're planning on running - something that has smaller runners with good port velocity and good flow would be super fun to drive on the street (which is why guys go crazy for some of the AFR head designs and why vortec heads work so well with tiny runner volumes)...

As a general rule - the more exotic the parts and higher the HP the more often you'll be tearing into the engine and rebuilding/re-freshening...

Orr89RocZ

iTrader: (20)

Good info to know. Any idea of that combo or the useage? Raced alot? I didnt think oil ring in the wrist pin would hurt as much if everything was put together well but oems dont seem to do that by design so there must be something to it. 40-58k is alot of miles on any performance motor, so its still impressive to me, but i agree avoid it if possible if you really are squeezing as much mileage as possible out of the build.

bwiencek

It was a ford 5.0 stroked to 347, quick info on it was 10:1 static compression, hyd. roller cam with a split duration in the 28x/29x range .54x/.55x lift, 112lsa (have to look up to get exact specs but that's what I remember), twisted wedge aluminum heads, trickflow street heat intake, 1.6 alum. roller rockers.

Probably 75% normal driving, 10% of the time at the dragstrip, and 15% hard street miles... Ran pretty darn good for the time - probably could have gotten more out of it with a proper computer tune instead of playing with the base timing, fuel pressure and MAF calibrations to get it to run good... At that time nobody was really doing custom tunes on the dyno (heck I think there was only 1 chassis dyno in town that I recall - now I think there are 5 or 6 within 30 minutes of here)

Building a 383 to produce Mid 400 HP/400+ ft-lb of torque will be fun and plenty durable on the street - heck GM makes a ZZ383 with over 400hp and I think it has a 2 year / 50k mile warranty so you know they're not going to put out something that won't do well over the 50k miles without repair... Getting into the 5xx hp range requires turning more RPM or components that will sacrifice a lot of bottom-end torque for the gains in top end HP and engines like that start to feel lazy on the street (IMHO)