hey guys heres the deal ive been trying to decide what type of motor to swap into my 88 iroc. ive though of big blocks,LSI's, stroked 350's everything but the one i think ive chosen is to find a junk yard 400 small block. then bore it to 4.126 and install a 454 crank to make it a 427 small block. then use a highly modified TPI setup (to keep it looking original) on top. any opinions? one question. will the stock computer with custom burned chip support this engine? supercharged?

it just has a ring to it dont it?....Supercharged 427 TPI

 

A 454 crank?

 

If you get a 454 crank in a small block 400 please show me....

I think you need to do more homework....

 

As was stated above you would have to get custom components to make a 427 small block. "If" I were to use TPI on a 427 I would get the Edelbrock base and Extrude Hone it to the max. Get the SLP runners and fully siamese them and then match them to the base. Next open up the plenum to match the runners and the new throttle body. I would use a 58mm throttle body at a minimum and consider a mono blade. Yes you will need a custom chip. Supercharging is another story. Hehehe. Allen

 

I think your the one who needs to do their homework.
Have u ever heard of the Shafiroff 472 small block?
Not cheap but not impossible.

However, I dont think I would ever put a TPI on something like that.

 

The biggest sbc that I found on the shafiroff site was a 434. I looked under "crankshafts" and "rotating assemblies" and nowhere did I find anything that said Shafiroff used a 454 (and I assume you mean a bbc) crank in a small block.

IIRC there are 454 sbc engines available, but, AFAIK, they do not use a 454 (bbc) crank in those engines.

 

I was referring to a BB crank in a small block.

I just finished my Small Block 454 so yes it can be done with custom components.. As far as in intake i would stick with a HSR or just a big throttle body.

 

That's gonna have to be a highly modded TPI but you'll have some crazy TQ.

 

you can get the 427 rotating assembly from summit from the hard core parts i think, it was only around 1900 if i remember right and came with good pieces, i think their was a special cam or their was something special that had to be ordered. i went ahead and built a 388 just for the fact that i saw some advantages and disadvantages to the build. once you get that large of a bore and stroke like a 427,434,454, which i had a 434 before, it is just hard to make it reliable and not saying it cant be done but the later model 350 blocks are not as strong or have as much extra metal as a early 350 block , say a early 70's late 60's .010 350 block, i have one out of a 70 camaro and i have done the comparisons. the jeep guy with the 454 is a great example, he did his build correctly and is reaping the benefits, just make sure before you go into to anything you research every last part because you will have issues from build strength to tpi compatibility, i would guess a stock tpi would not flow enough to feed a 454 as i have been told a stock tpi will not do it for my 388. do your research and spend the money to do it correctly or plan on all kind of issues and wasted money if you dont. p.s.- my longest post ever on this site.

 

Corkvette and ski_dwn_it are running Small Block 434s in their cars using MAF and running 10s.

It can be done.
IIRC a 4.155 bore, a 6" rod and a 4.000 stroke crank will get 434 cubic inches.

I would NOT use a stock TPI on this obviously . . . but a ported and polished SuperRam and a good set of aluminum heads would work.

 

i think a 427 with TPI is like trying to make a marathon runner breathe through a McDonalds Straw while running.

as Allen stated, you would need to enlarge all the TPI components to the max, even then it might not be enough.. you should look into a Superram if you need to be Emissions legal, if not, look into another EFI set up. Such as Holley's fuel injection systems.

 

A "454" crank, would be something like an Eagle forged stroker crank with 4.000 inch throw, to be usd with 6.0 inch rods. Its internally balanced, and has a summit part # ESP-440050006000

It's to be used with a 400 block with the large bearing radius. With a 4.125 stock sbc 400 bore, it would make a 427.

As for a 427 TPI, I think it would be a torq monster and fall on it's face above 1500 rpm's. It's been done before, and the TPI just don't flow enough tp feed the engine. If stock apperance is important, consider getting a LT1 intake, mod it to fit (www.lt1intake.com) get larger injectors, and it would have a chanse to breathe somewhat normally.

 

yeah i agree i need to do more reasearch but what i have found in some books i have at home say that if you use a 400 block (4.125) and use a small block 454 crank with a 4 inch stroke and 6 inch rods it is possible and equivalent to a 427. I know that the intake setup would be a challange but i know that with modifications or aftwermarket TPI setuyps they usually trade torque for HP and shift the curve up a notch. so i figured that with the Edlebrock base and fully ported and siamezed slp runners and plenum it should support it but i could be wrong.

 

You are right about the edelbrock base, and possibly getting some siamesed runners, they all do help out. But the problem is even if you port it way out, it still won't be enough, even for a 383 compared to a miniram or equilant.

When going as large as 427 with TPI, you're throwing away hp, big time, and no matter how much money you throw at the TPI, you won't get your dollars worth. If you really manage to get a 400 block,( hard to come by these days without cracks), and start building it, forget about tpi and look for something that would not be a BIG corke in your setup.

THis is something that should be done on a car that's to be used in a "stock induction only" class. Anything else, ditch it.

EDIT: You could use most of the stock TPI unit, but swap the intake, for a lt1intake. It would make it breathe up top, where all those cubes are going to need it. It's a fairly cheap mod compared to a miniram, and although it don't performs as well, it's lightyears aheat of the stock tpi runners and base.

 

ok i think i will end up going with the HSR that would be able to support it right? also i had a couple question about the block. i know it would be hard to come by but i know i could find one. do you know of anywhere i can buy a new block? and also since its a small chevy will the mounts,bellhousing,header location, hood clearance be the same or will i have to do some modifying. i plan to build this motor up until it is complete then swap it in place of the 350 tpi. boy that will be a screamer!

 

The stock 400 block where discontinued in the early eighties by GM, but GM sells bowtie (racing) blocks with 4.125 bore. They are expensive thogh, well over $2000 just for the bare block. Others are world castings with their "motown" block, $2419 fully prepped at summit. The last one, but no worse, is Dart "Little M" block. $2305 at summit.

I guess this makes it a bit expensive, since you need all the internals as well, This is why you don't see alot of these in thirdgens.

The cheapest solution, would be a rebuilt stock shortblock from a early seventies car or van that came with it. Tose rebuilt engines are just that, rebuilt. You will have to tear it down to use it in a performance setup, since no stock 400 has ever been a performance engine, so the internals are weak.

Other major problem, is the 400 blocks have a tendency to crack, I think it is where the crank is biltet into the block. The 4 bolt version makes it even weaker in this area. The stronger engine would be a 2 bolt block, machined to use splayed caps. this and other required machining makes it almost the same as a new motown block. Your call.

All smallblock V8's got revised in -86, so you would need another flexplate, a dual to single main seal adapter, a 400 balancer, an oils stick with tube (mounted on the other side on 400's) and possibly some other bits.

 

OR, you could wait with the "high performance" for a while, and just get a cheap shortblock and try it out with the TPI. www.unitedengine.com sells really cheap shortblocks, but I have heard people had problems with them. But surely other must have been satisfied aswell. They sell a rebuilt 400 for $495 + a $200 core charge.

I guess you could find others with these kind of prices aswell, look around.

http://www.unitedengine.net/Merchant...egory_Code=SB3

These blocks are not reccomended when going with a 4." throw crank though, it doesn't have the necessary clerance, and when you grind it, one often grinds into the water jackets. A stock block would be best used with a non stroker crank, but can benefit from longer rods.

 

ok i really appritiate the info you guys have given me its really nice to use this forum and talk to guys that really know thier ****. what would you suggest other than the 427? i would like to keep the small block but have quite a bit of CI's. and also somthing slighly easy and cheap to get the block from the junkyard. that guy with the 406 what did he use as a block and crank? 396? 415? any suggestions.

 

406's is stock crank, 0.030 overbored. Your best bet for your money is a 383 or 388, 383 is a 400 crank in a 350 and this is a very common build. Forged cranks are cheap for 383's too, so for the best bang for the buck, go with a 383. If you overboore it slightly, you'll get a 388. A 350 could also be stroked to 396, not as common, more expensive parts I guess.

I don't have any other reccomendations for you, all other swaps would mean alot of modifying. If you start with a rebuilt 400, or manage to find on in the yard, I personally would go with that.

 

hay I would build what you want to build. You can make the tpi work, but it will take money big injectors possible a 9th and 10 injector. U will have to hog out the system to the max I hope you know a machinest who can do some work like custom and expermintal with the top of the induction. I would see about splitting the top and adding more volume to it and custom tallor the runners for the rpm of the motor for its air needs. I would keep it under 5300 rpms, with some good heads you can have a real stup puller.---It will require lots of cash--I personaly will never rebuild another small block for race---big block = more hpand tork per dollar spent -- you can get 540 short blocks for around $4000 in AZ--can't remember the name of the place

Just my 2 cents take it or leave it

later and
GB

rk

 

I know the cost is an obvious factor,but after I weighed it up,it was far easier to get a new Dart block.It was $1699 from Shafiroff.Eagle internals are also very reasonably priced.A few years ago,putting together this sort of motor would have been very expensive,but it's a buyers market now,with a lot of cheap hardware about.Save yourself the ifs and buts with a used standard block which might or might not break.BTW my crank is a 400 crank and I have never seen it referred to as a 454 crank?

 

For a 4" or greater stroke in any stock GM small block your going to need to do a hell of alot of clearancing on the bottom of the cylinders, and the oil pan rails. And will have to run a small base circle cam, If your thinking about this seriously I would go with the raised cam, spread rail Dart Iron Eagle block, you can go as high as a 4.25 stroke with out much problem.

 

hey "tilstad" you wer talking about that 396. thats a 350 bored .030 over? and i guessing a stroker kit that you can throw in with out any mojor machining? i originally wanted to go with a 383 but it is getting way to common i think that 396 would be a great starting point. since i heard the cost and availibility of the 400 i think i will go with the dime a dozen 350 but make it an uncommon 396. i didnt do my homework on the 396 yet but i will, so reply if you want.

 

I don't know much about larger than 383 350 blocks, and after doing a search for a 396 smallblock, I found nothing. Maybe I'm misinformed.

Anyways, If you use a 3.850 stroke crank in a 350 block with a 0.030 overbore, it would give you a 393. A 4.060 bore would be a 398.7. Almost a 400 I guess. I don't know squat about how difficult it is to get such a crank in a 350 block, you'll have to do some research, but I have seen buildups of those cranks in stock 400 blocks, and as far as I know, there isn't more clerance in the 400 block than the 350. But I can't say this for sure, do some research.

I think one reason you don't see 400 inches and larger in a 350 block, might be because builders just go with a 400 block if they want that big displacement.

If you filled the water jackets and grind heavily, and hope to not grind into the jackets, maybe if you lucky, a crank with 4 inch throw could get into a 350 block. But this is serious engine building, for pro's, who can afford to use up some blocks trying. The older block might have more meat around the water jackets, some engine builders claim this. With a 0.060 overbore, it would be a 414, but I've never heard of this, probably because it isn't possible, at least not with a 350 block. But then again, it might be.

The largest smallblock I've heard of is a 482, raised cam, spread panrails, 4.25 crank, 4.250 bore. It's all maxed out, not much strenght left in the block. I think I have a book about a guy making them, but it's costly.

 

alright thanks for all your help because i am one of tghose guys that get to anxious and just jump the gun and screw stuff up because i didnt do any resaerch. i am going to post a thread specificlly to find out what has to be done to the block to make a 396 so thanks again.

 

I think I found it, On some new crate engines to save money by not overboring the block, they go with a longer throw than the usual 383 setup. So they stuff in a 3.800 crank and with 4.000 bore they get a 383. 0.030 over nets a 388, and 0.060 over gives a 393.56.

Additionally I found a 3.875 crank in the sumit catalouge, and I guess that's supposed to be used in a 400 block, but could very well also go into a 350 with minor grinding. It makes a 389 on stock bore, 0.030 over makes a 395.4 (maybe this is what some have called a 396), and 0.060 over makes a 401.33

 

ok so if i got a 4-boklt block bored it .030 over and got that 3.875 crank with stock rods it would come out to a 396 roughly. to bad they dont make a rotating assembly for it. also this i should know but i dont what size rods are used in a stock 350? 6inch? thanks again

 

Stock 350 rods are 5.7

The thing abouth this odd size engine builds, is that some parts may be hard to get, or pricey, say for instance pistons. Or maybe you find affordable pistons, but if you ever need to overbore it, maybe there isn't any in that size. You'll have to sum up the whole rotating assembly, including rings, calculate compression and look at piston height, quench and valve reliefs. Also knowing what ind of head your gonne use is mandatory. You could get some help about some of these aspects when your bying some of the parts. But look out, change the rods, you need new pistons. Change the pistons, and you may need a cam with less lift. lot's of things to look into. A safe bet would be to copy a buildup, if you can find one you like.

 

Yoiur dreamin'
You'd be lucky to get one to bore .060. Aint no way without an aftermarket block and crank.

 

I totally agree.
Also, if this topic will continue will you PLEASE stop calling the 4" stroke crank a "454 crank" , just call it a 4" stroker. The old days they used to call the 3" stroke a 283 crank because it WAS a 283 crank .

I love the idea of the 454 sbc. Poping the hood and tell somebody it's a 454.... very funny when the fresh kid thinks he's going to correct ME, haha.

I also believe no amount of porting is going to let a 400+ cube sbc breath through TPI effectively. Like somebody said, a marathon runner with a straw. You're "torque" wouldn't be as high as some might think. Maybe at 1000rpm it'll peak but this isn't a 1 speed vehicle with street gears . Match the motor with an appropriate size of components. Don't put TPI on a healthy 400. If you build up a stock 400 and want to keep TPI than don't waste money on exotic parts. Just rebuild it with the cheapest pistons you can find.
Here's a reason to stay far FAR way from a stock style TPI on a big cube motor; BBC's like big cams and big heads, they make MORE torque EVERYWHERE than when matched up with smaller parts. So please reconsider your intake selection if you decide to build a 400. I have a friend that has a 2-bolt main 400 that we're going to build up for his mint 84 oldsmobile.

 

I think 396 SBC is a pretty common build. The block itself is a 350 block bored 30 over so it will be cheaper, and I beleive it's just a 3.875 crank with that. Does this engine require clearancing, or is about as easy as a 383 build?

 

I will confirm that a 396 (395) cu.in. SBC is a 350 block bored 30 over with a 3.875" crank. I built one this last Summer and am running it in my '87 IROCZ. You will definitely need to "burn" your own chips.

 

BTW: When I started researching my large cubed SBC project, I considered first the 383, but alot of people build these, I wanted to be different. At this time, the Magnum TPI articles came out in GM High Tech. They built a 395.7 cu in motor. I finally went that direction. But in the process, I considered several sizes, 427, 434 and 454.

The 427 SBC is a bore of 4.1875" and a stroke of 3.875".

The 434 SBC is a bore of 4.1550 and a stroke of 4.000".

The 454 SBC is a bore of 4.1875" and a stroke of 4.125".

For the above motors, I was convinced that the MoTown block had to be used for reliablibity and strenght.

If you go to www.colacranks.com, they have a nice chart given the above info on SBC cubic sizes.

 

doc, I was under the impression that most 427's were the 4.125 bore old 400 2-bold main blocks with a 4" stroke.

 

How are the characteristics of this 396 of yours? In what way do you feel it differs from other builds? Does it not rev?(lol, this could put an end to the whole 377 thing)

How much clearansing did you have to do on the block? Do you feel there is a downside to the build?

 

There are an infinite number of ways to achieve 427 cubes. On the practical side, it would depend on what the manufactures are willing to produce & market. But, yes you get 427 cubes with a bore of 4.125" (which is common) and a stroke of 4.000" ( which is also common). So I figure that the bore & stroke combo above in this post was the "first" SBC 427 in common use.

Today, a stroke of 3.875" for some reason is becoming popular in engine biulds. I am not an engine guru, but would not the 3.875" stroker 427 rev higher than the 4.000" stroker 427?

My 396 (395.422 cu. in.) appears to want to rev very well, but I was after a butt smacking torquie motor. I was planning to have the peak power come in at about 5600 to 5800 RPM. And, therefore, not rev above 6000 RPM which would give me total reliability having an all forged rotating assembly. Also, with a ported SuperRam, I am probably limited to an RPM limit of around 6500 RPM of less maybe.

As far as clearancing is concern, you need to clearance the bottom of the cylinder bores and the oil pan rails. Also, you might need to dent the oil pan itself. This would depend on your specific parts. I had an engine shop help me with the block prep and with the rotating assembly.

 

A longer stroke can affect how fast an engine 'REVS' but the weight of the rotating assembly has much more to do with it. I know of 4.5" stroke motors that rev quickly and shorter stroke setups that are sluggish.

Longer stroke engines have a limited RPM range but that limitation is only based on how good the rotating assembly is. Longer stroke = more piston speed. We have built 4.25" stroke motors and turn them 7800 and plan on a 4.5" motor that will turn over 8000.

If you use good parts and keep your stroke around 4" you should be fine going upwards to 6500.

 

To add to what TPIJeep has said, an engines RPM is almost completely independant of it's stroke. The only time a stroke comes into play is high side loading of the pistons in the bore!
The things that directly effect an engines redline are the cam and heads. Basically it's breathing ability. A long stroke engine will make more power at lower RPMs because of it's torque advantage (torque and speed being the variables in power).
Most long stroke motors were installed with heads that were small even for the SMALL unstroked engines. This in turn make the long strokers feel like dogs up high because of the air flow problems.
For heavy vehicles, or vehicles with only a few gears it's better to have the horsepower at lower engine speeds because this will generally get the vehicle moving from 0mph without lag.
If you build a big cube motor you should put big cube parts on it.
I like to remind people that heads and cam are the REAL horsepower makers. Engine displacement just dictates at which RPM you'll make that power (this is if the bore is the same size and only stroke is being compared).
So if you build a 454 small block and install heads from a 305, expect a redline lower than a diesel. If that 305 made 400hp at 6000rpm then expect the same horsepower but at a lower RPM, like 4500 or so. Remember, heads flow air, cams let the engine flow that air and horsepower is directly proportional to how much fuel and AIR you get into an engine! The reason fuel and air are directly proportional to power is because you can only extract so much energy from fuel, the more fuel you burn the more energy is released into the system. If the timing is too retarded lots of the energy goes into the exhaust and cooling system (expelled as heat). Hope this paints a good picture for the new guys reading this thread.

 

L98+t5:

How are you doing on your research and thoughts about your big cube SBC? This is your thread, how are you coming along?

 

well i started looking at the 427 as the post states. but have been looking at all of my choices. and i can get a 427 but it wont be very cheap. i would have to get a motown block and world rotating assembly. about 4,000 just for the short block. so i started looking into other combos and i know i didnt want a 383 but when i saw the 396 combo (350 bored .030 over and a 3.875 crank) i see this would be the best setup because i want somthing a little different than most people but i want it to be fairly inexpensive. and i think that it my solution . ---SC 396 SBC--
thanks for all the info guys it really gave me a couple different perspectives to help narrow it down

 

Thats pretty much how I felt, so I built a 396 SBC.

 

alrighty then thats what i think ill do. you said that you had to clearance the piston walls and the oil pan rails right. also did you buy a rotating asembly or did you have to buy all the parts separatly. i like it all forged at 8.5:1 pistons. (supercharged)

 

alright this is pissing me off i have been looking at stuff for the 396 and i keep seeing different bore sizes. so is it .030 or .060 or .090 over? i was told it was .030 over but the saw a thread where someone saifd it was .090 over? whats the deal?

 

Math, it's your frieeeeeend.
8 cylinders displace (8 x stroke x ((bore/2)^2) x pi) ci . So 396 = 8 x 3.875 x ((bore/2)^2) x 3.1416 , solve for bore .
4" bore .030 over ... is that your final answer? You've still got 3 life lines! lol
The actual displacement is 395 .

edit: I need a life line, I'd like to call a friend. That's what I get for trying to simplify this. Thanks doc for pointing out my error.

 

JPrevost:

Very sorry, but you are wrong.

A 396 (or 395) SBC is (at least the one that I built) a 4.000" 350 block bored .030" over so the bore is now 4.030"... The stroke is 3.875".

To confirm this do the math:

Cubic inches = 8 x bore/2 x bore/2 x 3.14159 x stroke

in this case we have: 8 x 4.030/2 x 4.030/2 x 3.14159 x 3.875

Which equals 395.42 cu.in.

If you go to the site that I referenced above, you will see several combinations of bore and stroke which make up many of our favorite displacements.

l98+t5: I purchased the rotating assembly as separate parts, a Callies DragonSlayer 3.875 crank, 5.85" Eagle H-beam rods, and SRP pistons (part # 148988) with compression hgt of 1.213" and dished 14cc. With 64cc chamber heads, I ended up with a compression ratio of about 10.0:1...

The DragonSlayer crank is forged and is probably the best forged crank for the money. This is the foundation of the rotating assembly, so I did not want to go cheap here.

 

Boy do I feel stupid. Big brain fart. Thanks doc for pointing out the obvious... area = Pi R^2, lol. NOT Pi D

 

Yea, I was concerned that I would pi$$ you off if I corrected you.

 

Nah... to be certain it helps to add a when ever possible. This lightens up the tone or a reply. The whole reason for smilies is to form a virtual tone of voice. Works rather well don't you think .

Anybody use the GM crank that is 3.8"? They made it so that they could offer a 383 without the overbore. Build a 350 block .060 over with the 3.8 stroke. That would be a 394 . Aren't I creative when my math works.

 

cool thanks for the help i hope it dont **** you off but im probably gunna save that list you gave me i know it might **** you off but i want to know what will work before i satrt the build because im only 17 and have like no cash! thank you guys for all your help.

 

hey doc i see you have 5.85 rods why is this? also i was wondering if i could get pistons to keep all the same stroke and bores of the 396 but bring the compression down to about 8.5?