High RPM V8's Part Two: Chevy VS Ford

"GhostZ" (GhostZ) 09/14/2013 at 21:47 • Filed to: V8s, Ask Oppo, GhostZ, Chevy 302

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Help me Oppo, you're my only hope! In my !!!error: Indecipherable SUB-paragraph formatting!!! we arrived at a pretty stout conclusion: Ford Windsor FTW. But now a new challenger has reared its head.

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The Chevy 302. The Legendary SCCA Z/28 motor. It was a 4" bore 3" stroke engine (same as a Ford 302W) with a ton of high-rpm parts. Now, obviously, getting ahold of one of these motors is pretty much impossible for a budget build. But that doesn't rule out its capability.

You see, the 240z can fit a Chevy 350 with off-the-shelf components, the support for the swap is a lot higher. And I may or may not have recently found a source for a very cheap 350 out of a mid-70s Corvete. While I hope it is a L82, it may be a L48, the base model engine, rated at 180HP or so. Let's assume it is an L82, which has 4-bolt mains, and let's assume that even if it isn't, I could acquire an L82 for the same time/cost as a Mexican block 302.

Unlike the Ford 289, a shorter stroke is readily available: for about 800$ you can have a 3" stroke. It's not as good as the 289, but it has stronger 4-bolt mains, and a taller deck height that would allow for about the same peak RPM as the 289, but with some added weight.

So now here is my question for Oppo, which bottom end would yeild the highest potential HP/dollar for 7500+ rpm? Assume that the top end is going to be quality and where most of the money is going to go. My power goals are either 350-450 N/A, and possibly 550-650 on a turbo later down the road, so I don't want to buy any aftermarket components that are good for 450, but won't take 650, so that I don't have any redundancy in parts.

Here's the two theoretical builds. Let's assume that I can get both engines for about the same price, and that the cost of the custom mounts on the Ford is about the same as the cost of the forged crank and rods on the 302, which (while available) are going to need to be purchaged for it to work, whereas the 289 could come together using easy-to-find stock parts.

Windsor: 289 CI Hybrid
Mexican 302 Block (~2" mains, 2 bolt)
289 Stock Crank (2.87" stroke)
289 Stock rods (5.110" rod)
302 Pistons: (1.6" Compression height)
Deck Height: 8.206
TDC: .061" below deck.
Compression ratio on 69cc heads, 0.03" gasket, and flat pistons (For comparison): 7.7:1
4000ft/min mean piston speed at: 8250rpm
Rod/Stroke ratio: 1.78
Bore/Stroke ratio: 1.39
Weight: -25lbs from stock
Position: About 3 inches further back and a few inches lower than the 350, almost an front-mid-engine position.
Cons: Custom, expensive engine and transmission mounts. No aftermarket crank.
Pro: Great fit if mounted properly, excellent-high RPM possibilities, sexy bore/stroke ratio.

Chevy 302 Hybrid
Chevy L82 Block (unknown mains, 4 bolt)
Aftermarket forged crank (3" stroke)
Aftermarket forged rods (5.85")
350 stock pistons (1.56" compression height)
Deck Height: 9.025"
TDC: .115" below deck
Compression ratio on 69cc heads, 0.03" gasket, and flat pistons (For comparison): 7.2:1
4000ft/min mean piston speed at: 8000rpm
Rod/Stroke ratio: 1.95 (!!)
Bore/Stroke ratio: 1.33
Weight: +25lbs from stock
Position: Significantly more forward than the stock motor (due to the rear-mounted distributor and simple-yet-cheap off-the-shelf mounts) with more weight at the top. Clearance for throttle bodies or velocity stacks could be difficult unless I raise the hood on the inside.
Cons: Heavier, worse position, slightly lower RPM, more expensive, and it's a Chevy! D= (not that big of deal, but I'd rather see the car with a Ford engine...).

Pro: 4 bolt mains. The money I save on mounts could go to some forged rods and the crank, so that between the good rods, crank, much better rod/stroke ratio, I think that the heavier, longer stroke assembly would probably be able to spin at a higher RPM due to the improved strength of the components for the same money.

So the real question is: Does the bulk, height, and not-ideal positioning of the 302 get outweighed by its much better rod/stroke ratio, stronger mains, and stronger (if heavier) rotating assembly? Could it actually reach a higher RPM with a built top end than the 289, despite the 289's short stroke?

Assume the added cubic inches are completely outweighed by the added weight and the lower compression ratio of the 302.

Assume the drop in compression ratio doesn't matter (if I plan to boost it later, that is) and it can always be adjusted depending on what heads go onto the motor, and aftermarket pistons. So I could put small-chamber heads on now to get either one to 8.5:1 easily, and then when I go to boost, drop it back down with new dished pistons.

I don't want to go Chevy, but maybe if I drop the motor in, shave off all identifying marks, and (after all of this cobbling together) I could just tell people it's a custom 302, neither Ford, nor Chevy.

Frank Grimes > GhostZ 09/14/2013 at 21:55

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There is also the chevy 305 and 307 not sure about the 307 but the 305 has limited head choices due to the small bore I believe. Basically I dont know much but it gets you the small cubes you want.

pdthedeuce > GhostZ 09/14/2013 at 21:58

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are you planning on running a 8.5 compression ratio naturally aspirated ? that seems really low . lots of people run 8.5 on turbo motors .

pdthedeuce > Frank Grimes 09/14/2013 at 22:04

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run away from 305's and run further from 307's

desertdog5051 > GhostZ 09/14/2013 at 22:06

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That is a tough call and you have certainly done your homework. About the only thing I can suggest is The Ford will be quite a bit more expensive to play with than the bowtie.

GhostZ > pdthedeuce 09/14/2013 at 22:16

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8.5 isn't low for a single cam, carburetor, OHV on 87 or 89 octane street gas. Sure, I could bump it to 9:1 and be at the limit, ot 10:1 and run 91/93 octane and probably get 10-20% more power... but I'd rather run it low for a year or so and then get boost on it.

8.5:1 is pretty bad for a modern EFI DOHC engine. Consider that the Ford 5.0 runs on 10:1 compression and 85 octane, but in order to do that, needs cylinder wall molecular coating, some pretty fancy injection technology, and state of the art heads and pistons.

GhostZ > desertdog5051 09/14/2013 at 22:18

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What in particular is more expensive?

I figure the aftermarket for the 302/289 is about as big as the 350, but are most components for a Ford 302 actually more expensive?

GhostZ > Frank Grimes 09/14/2013 at 22:20

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The 305 is much worse (long stroke, tiny bore, generally bad build quality) and the 307 had a slightly larger bore but still longer stroke than the 302, and is probably pretty rare since I don't know if it was even sold in the US.

pdthedeuce > GhostZ 09/14/2013 at 22:23

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the chevy 302 you referred to ran 11:1 compression . to run the rpms you aspire to requires better than average heads , a pretty big cam and some serious compression . I just don't think you can get where you want to go at 8.5 .

desertdog5051 > GhostZ 09/14/2013 at 22:25

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Just going off he Summit Racing catalog. Everything they list identical (or very similar) for Chevy/Ford parts, it seems the Ford is always more expensive. Do not get me wrong, I am a Ford man. If I was to hot rod a motor though, I would probably go Chevy.

BlazinAce - Doctor of Internal Combustion > GhostZ 09/14/2013 at 22:31

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Word on the street (back in 69) was that no car had more sheer mechanical presence than a properly equipped Z/28 Camaro, not even a Hemi Mopar. I remember C&D pitched the same Z/28 against two or three iterations of Ford's Trans Am entries, and it came out on top every single time.

TheLOUDMUSIC- Put it in H! > GhostZ 09/14/2013 at 22:35

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I still vote GM, even though Ranger. I've always had better luck with über high GM miles than Ford miles.

GhostZ > pdthedeuce 09/14/2013 at 22:41

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I'm not so much concerned about power losses N/A as I am later on as a turbo build. Assume I drop about $3000-$4000 in heads (300+cfm @ .7"), high duration (250-260) cam, EFI and ITBs. I could totally run a small cc head and/or domed pistons and get a reliable 9:1 or 10:1 (pushing it) on pump gas without predetonation.

But then, if I wanted to turbo it reliably, I'd need to get entirely new heads and pistons, or rods and pistons, to drop it back down.

It's possible that I could go with a longer rod and shorter piston combo and try to aim for a better deck clearance. I'll do some numbers:

1.261 Compression height piston + 6.2" rod = .064 clearance, meaning about a 7.9:1 compression ratio with 69cc heads, .03" gasket and flat top pistons, or 9:1 with a 58cc head as I said I could do, and then drop it down when I go to turbo it.

Alternatively, going with a longer rod (6.25 instead of 6.2) gets me a clearance of .014, resulting in a 10:1. That also gets me an insane 2.083:1 rod/stroke ratio! That's easily the highest HP combo I've tried so far. The problem is that, unlike going with the stock pistons, I have to buy two sets of pistons to get to the eventual turbo build, one flat-top for n/a and one dished for turbo, and I'm not sure how strong a 1.261" compression height piston is when dished, especially not against a turbo.

From that high compression combo, I would need a piston with a 20cc dish, or new heads with 30 more cc volume in order to drop the compression ratio back down to 8:1 for a turbo. It sounds temping, especially since I'd get much more N/A power, but the economist in me sees it being really inefficient having to buy new heads or dished pistons after I already bought some later on.

GhostZ > BlazinAce - Doctor of Internal Combustion 09/14/2013 at 22:46

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It has all of the qualities of being a great race engine, so using it as a guide to building an SBC really appeals to me. They were supposedly underrated at like 300HP.

But of course, it was an absurdly expensive motor to buy nowadays, so it's more of an inspiration/blueprint than a feasible drop-in.

I think the Z/28 302 was a boring production 350 built to 110% race spec at 400HP. Whereas the Hemi Mopar was a 400HP engine built to 50% of its potential output. It takes good knowledge and some skill to pull the 600-700HP that the Hemi is capable of out of a stock motor, but it can be done, but the stock motors just weren't built to the same quality specifications as the Z/28.

Frank Grimes > GhostZ 09/14/2013 at 22:47

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It was by the crap load.

GhostZ > TheLOUDMUSIC- Put it in H! 09/14/2013 at 22:49

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Mind going into more details?

This engine is going to be built to absurdly high spec, and then dialed back from its potential and going into a very lightweight car, so my goal is to actually keep torque low and manageable and RPM high. Long-term milage use doesn't bother me as much (this car isn't going to be seeing 20,000 miles a year) since most components will be replaced, however, I need a good block and base goal to start from so that when I get there, it will be able to perform reliably without tearing itself apart.

GhostZ > Frank Grimes 09/14/2013 at 22:52

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Sure enough, it was. Wiki says it showed up in the Chevelle, which means it was everywhere.

Still, it's dimensions aren't as favorable as the "hybrid" 302, but I could look into its short-stroke 3.25" crank if I wanted to build a 330-something and give up some RPM for cost.

pdthedeuce > GhostZ 09/14/2013 at 22:54

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I think I may not have made myself clear . I think you should build it at 8.5 : 1 , because that's great for the eventual turbo . I just don't want you to be disappointed if the motor is lazy and will not rev very high while N/A . I also believe 350 hp to be unrealistic at that ratio with that little displacement . Let me state that I'm not trying to troll here , I'm just trying to help out on a subject I have some knowledge and experience with .

TheLOUDMUSIC- Put it in H! > GhostZ 09/14/2013 at 22:55

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Well, I am a Chevy guy, soooooo...

I have heard that building a stock block 302 can be a problem, because I've heard of blocks splitting down the valley at 5-600ish HP.

Edit: Dont get me wrong, I still wanna throw a 302 in my Ranger, but I don't think its such a good idea for much more than street use.

GhostZ > pdthedeuce 09/14/2013 at 23:04

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Your input is valuable and exactly what I made the thread.

I think 350HP is totally possible with these motors. Remember, they're spinning to 6000+ rpm (peak power around 7000-7500 probably) on high duration cams, high lift rockers, and good ($2000) heads. They need to flow about 600cfm to easily reach that power or more at those RPMs, which isn't crazy at all. I've specced out a Frod 302 to similar specs in an engine simulator (Engine Analyzer Pro) and got it to about 375-400 with 8.7:1, heads, intake, exhaust, and cam.

The Z/28 302 made that kind of power at a lower RPM and with 11:1 compression. Drop the ratio a few points and add 2000rpm onto the top end and it looks promising.

If I put stock heads, cam, etc. on it? It would probably rev to 5000 and then quit out because of pumping losses, so yeah, that would be stupid.

Take the two motors I have put here, and put on top of them:

Solid roller cam, high duration
Standalone EFI
Individual throttle bodies + stacks
Decent headers chosen for high-RPM use.

Does that make sense? I think 350HP is more than reasonable. MPG might be low and idle might be high, but it can be done.

A vast majority of the money in this project will probably go to the top end, to get great airflow at high RPMs for when the turbo is put on, rather than spend less money and get an average mid-RPM build that wouldn't get the same gain from a turbo.

To put the entire build in summary.... "the replacement for displacement is RPMs."

On the other hand, I have the itching to make a 10:1 compression engine, and then when I get a turbo, replace the intake, fuel lines, EFI, etc. to run on E85 and put 8-10psi behind it with an intercooler. But between issues with E85 conversions, cost, and availability, that might be stupid, but very appealing for peak power.

GhostZ > TheLOUDMUSIC- Put it in H! 09/14/2013 at 23:08

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I'd keep it N/A around 350-400HP until I went with a turbo. The Windsor blocks crack around 450-500HP, so it's good to know that the SBC can take a little more abuse. I doubt I'll ever push it past 650HP, and it won't even have more than 450-480 ft/lbs. I think the problem is that most of those builds probably are making 600HP at like, 5500 rpm, where they are also taking on 550+ ft/lbs, and that torque is what breaks components.

GhostZ > desertdog5051 09/14/2013 at 23:12

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I'm seriously considering it.

My biggest drawback is the mounts. I think performance-wise, the engine is a wash, the SBC will definitely cost more to get running, but it would cost less to build all the way and to get it in the car. The 289/SBF would be cheap to get running, but cost a lot more to get it in the car and need to basically be overhauled if I want to push it past 400HP. The 289's better bore/stroke ratio is offset by the 302's better rod/stroke ratio too, so they really are in tight competition.

That being said, the Ford 289 also has way better handling characteristics in the car. It's lighter, can be mounted significantly further back (and if you do cut into the firewall, can turn the car front-mid-engined) and a few inches lower. Whereas the SBC, which probably will produce the same power (for a bit less $) is going to add weight to the nose and be tall enough to make fitting the hood difficult if the intake stacks get too long.

pdthedeuce > GhostZ 09/14/2013 at 23:14

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Good luck on your build .

Frank Grimes > GhostZ 09/14/2013 at 23:19

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have you checked out the GM LS 4.8?

(3.779") bore and 83 mm (3.268") stroke 270 horsepower (200 kW) to 295 horsepower (220 kW) and 285 lbf·ft (386 N·m) to 305 lbf·ft

It would get you a much better maybe lighter engine.

Sorry if I'm wasting your time with my suggestions I am just interested in your decision process and what you are looking for. I think I just enjoy bench racing different engines and stuff for some reason.

GhostZ > Frank Grimes 09/14/2013 at 23:25

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All suggestions are good. I'm trying to stay away from LS engines becuase I don't know if they use the same mounts as the Chevy ones, and they seem like they are more expensive to build and get ahold of. I could be wrong though, so I'll look into it.

Frank Grimes > GhostZ 09/14/2013 at 23:38

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They seem cheap to me. Well maybe not as cheap as a 350 chevy but seem like they would be in better condition and would require less machine work. I think mounts are the easy part. They are easy to make in a worst case scenario. The problems are the headers and steering shaft interference and oil pan fitting over cross members. The extra expense would be if you want to go carbed is the manifold carb and the MSD ignition control box. If you are in the USA check out LKQcorp.com I go on there all the time looking at the LS motors to swap into my mustang. There is a 4.8 out of a 2005 GMC sierra for $925. There will probably some upgrades needed to be done stuff like cam, new bearings, rings forged pistons, valve springs get the bores cleaned up if needed.

Union of Smog Techs of CA > GhostZ 09/14/2013 at 23:57

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http://forums.hybridz.org/

All V8 questions have been answered in the belly of that beast.

GhostZ > Union of Smog Techs of CA 09/15/2013 at 00:19

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Oh, I know. I've browsed a bit. But I wanted to get some Oppo opinions becuse what I'm aiming for is a bit... non traditional. I'm not really content with getting and off-the-shelf 350, stuffing it in there, and then burning tires for fun at 300HP @ 5000rpm , even if it would be simpler and easier to do.

Union of Smog Techs of CA > GhostZ 09/15/2013 at 00:44

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I know, everything and it's mother has been done, someone was making a flat plane crank awhile ago, then a guy was making a twin cam L head out of two or three KA heads, crazy guys with money, hard to be original! I spend five minutes there and I'm looking for a Vq30DET, never knew was better block!

GhostZ > Union of Smog Techs of CA 09/15/2013 at 00:46

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Haha, I saw that DOHC L engine a long time ago actually. Blew my mind. Those guys are truly insane.

I remember one build a while back was a twin turbo VK45DE in a 240z. It had about 900HP in a 2600lb car. I've also seen people try to stuff viper engines and shit into them too.

I'll try to stay on the "marginally original, without blowing the bank" happy zone with this. A high-RPM hybrid 302/289 is pretty unique for a street car, especially when cheaper builds would yield more power from the same starting point.

Union of Smog Techs of CA > GhostZ 09/15/2013 at 01:41

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There are those silly little 4.3 L99 Chevy V8s, kind of a cool tribute to og small block, could spin pretty high and use corvette intake stuff too.

Have you seen anyone do a VK50DE yet? I've never even seen an FX50 on the streets, engines probably still pretty expensive and then all the damn NATS to deal with.

GhostZ > Union of Smog Techs of CA 09/15/2013 at 02:01

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Do you mean VK50VE? (The V is for "continuously" variable valve timing, they didn't make a VK50DE) I haven't heard of any swaps from that, probably because of the difficult availability and complication. But I'm sure once the engines proliferate down to cheaper models in the next 5 years or so, they'll get picked up.

I would like to see someone get direct injection on a stateside VK45DE. I'm going to miss that engine. According to wiki, the J-spec VK45DD has an 11:1 compression ratio.

EDIT: Also, the L99 is basically the same spec as a Chevy 302, but with a smaller bore. I don't know if they can be bored back out to 4" or if the blocks won't handle it. Either way, they come from a 90s era 305-based block, so I would be a lot more wary of them compared to a late 70s corvette L82 in terms of reliability. That being said, they do offer some of the benefits of the higher-tech and stock EFI LT engine over the original 350.

Union of Smog Techs of CA > GhostZ 09/15/2013 at 02:05

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See, I've never seen it or I'd know that! Actually that makes me not want it now, I'm tired of silly solenoids and crap that can go wrong, back to VK56DE dreams.

GhostZ > Union of Smog Techs of CA 09/15/2013 at 02:08

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It's amazing how underrated that engine is though. Most people don't think "400HP V8" when they think of Nissan, but long before the 5.0 came out they were putting down numbers comparable and better to the Ford Modular block, and even higher in race trim.

Paul, Man of Mustangs > GhostZ 09/15/2013 at 02:10

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Windsor blacks can take up to 650 hp with a girdle and a few other parts, as well as a conservative tune. Do all you can to avoid detonation, so don't be tempted to advance the timing for maximum power.

Paul, Man of Mustangs > GhostZ 09/15/2013 at 02:12

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I'm a handling guy, so I'd go with whichever one gives the better handling characteristics. And is a Ford. Yep. Totes unbiased.

GhostZ > Paul, Man of Mustangs 09/15/2013 at 02:31

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Really? That's good news. I'll look into what these "other parts" are. If it means switching to a 351 and modifying it with a custom crank though, in addition to more block reinforcement, that might be out of the question since for that price I can get a good aftermarket block.

AxelTrap > GhostZ 09/15/2013 at 10:10

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Their is also the chevy 377 combo. 400 block 350 crank, 4.125 bore 3.48 stroke. With custom pistons I think the shorter 3.25 of 3.00 stroke is possible.

Paul, Man of Mustangs > GhostZ 09/15/2013 at 14:04

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I think it's primarily just a stud girdle, but I've been told that a good one will raise the hp capability quite a bit. But there's also no substitute for a blueprinted block. Which means grinding down ALL the parting lines, triple checking every tolerance, radiusing corners, etc.

MrBillG59 > GhostZ 09/15/2013 at 17:38

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Remember, a good rule of thumb. There are two ways to make horsepower, cubic inches or rectangular dollars.

So, those mountain-motor pro-stock engines produce about the same horsepower as a Formula 1 engine, for about 1/10 the cost.

You should always start with the biggest displacement that the block you chose came in, barring any weird overbores. So, why start with a 283ci Chevy when the 350ci exists (and will weigh the same finished) or a 260ci Ford when the 351ci exists. Warning there is also a 400ci small-block with siamesed cylinders, but it is considered fragile (but also 50ci more than the 350ci so it will produce more power, but probably not be as rugged).

You are also looking at some very old engine tech. Unless you are doing this to prove something, just go to a junkyard and pick up an LS7 or other LS engine or if you're a Ford fan and your engine compartment is wide enough one of those cool Coyote engines. Big HP right out of the box.

You should also study what crate engines are available from reputable builders. The back of Hot Rod magazine has dozens of offerings complete with HP and torque figures so you can choose between high RPM power or low RPM torque to fit your needs.

MrBillG59 > GhostZ 09/15/2013 at 17:40

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The Hemi Mopar was advertised at 425hp but was well known to produce more like 500hp right out of the dealer lot. It was massively underrated for insurance purposes.

GhostZ > MrBillG59 09/15/2013 at 18:31

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Good advice, but nothing very new or useful for what I'm doing.

Power is made through Displacement (how much air you can suck in) RPM (how many times you can suck that air in a certain period of time) and Volumetric efficiency (how much air actually ends up in the cylinder, boost levels, compression ratio, and pretty much everything on the top end goes into improving this). You can trade one for the other and end up with the same power.

Since I'm rebuilding the top-end anyway, starting with a 351W would be stupid . Why? Because any displacement increase I get is offset by the loss in peak operating RPM (double the stroke, you double the speed of the pistons and further increase the g-forces the stock components have to handle for an RPM), because all it has is a larger stroke. This wouldn't matter if I need more torque, but I don't. 250 ft/lbs is plenty, what I need is more power without increasing the torque too high.

To make up for this, Ford included stronger mains and a taller deck (better rod/stroke ratio reduces slightly the force on the piston) but it would be impossible to bring that stroke down low enough so that I could run it to a higher RPM and reduce the torque being made.

But that being said, I'm not looking for big HP, I'm looking for a specific kind of power application: high rpm, low torque, moderate displacement, low boost. If I take a 30% hit on displacement, that's totally fine, I can make it up later with a 30% higher boost, since we're talking going from like, 6psi on a big block vs 9psi on a small block, which (if properly cooled) isn't going to make a huge difference in its ability to run, but just might reduce engine life a little. It wouldn't surprise me if a sophisticated turbo system and well-built components could pull 15psi out of a small block before it blows. That's way better than any tempermental low-RPM stroker motor you can buy. There's a reason people ignore the Ford 460 and just get 5.0s and slap an ebay turbo on them. They can make 350-400HP for $350-$400.

I'm wary of newer blocks because of the smaller aftermarket, the obscurity of parts, and the adaptation of technology. It would be a pain in the ass to take a 2004 motor and put it into a 1970s body, I'd have to get entirely new engine management and deal with any variable valve timing, sensors, etc. on the motor that it needs to run. I'm trying to hit a balance with moderate displacement (~5l), moderate RPM (~7000, which is moderate in today's world) and moderate boost (~6psi) so that when the parts are chosen carefully to work well with eachother, I get the desired effect.

I estimate that I can put together a bare-bones-but-working Chevy 302 for around $2000 (most of the cost is in an aftermarket 3" crank) and get it in the engine bay for $1000. I could get a Ford 289 for a couple hundred, but I have to custom-make a crank with a new block if I ever want to push it over 400HP and the mounts are expensive, so the Chevy 302 looks like the best bet.

GhostZ > AxelTrap 09/15/2013 at 18:48

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With a 3" crank, that would essentially be a Chevy 302 with a .125 overbore. Google tells me that the 400 pistons had the same compression height as the 350 pistons (1.56") so if I ran it, I would need custom pistons or rods from the start, since none of the small block rods (that I know of, which isn't most) won't fit well. The stock rod is 5.7", and the 383 rod is 6", but there's nothing in-between that lets me run a stock piston. In the 302 build, I can use a 327 piston, which has a higher compression height, but with a .125 overbore I can't.

It's possible I can just go with the 302, and then later bore it and put in 400 pistons though.

Another interesting combo that was mentioned is a "327" using the Chevy Monza's 262 3.1" crank instead of getting an aftermarket 3" crank. Though finding one would be pretty difficult. If I did that on a 400 block, I could run a 4.125 bore, 3.1" stroke, and end up with a 331 with 7:1 compression since the added stroke does make up for the short rod (assuming 58cc heads and no piston dome/dish) The bore/stroke ratio is about the same as the 302, but its rod/stroke combo is pretty close (1.84 vs 1.9). I take a few hundred RPM hit in peak rpm, gain the added power of the 4.125 bore, and can still put it together with off-the-shelf parts so it comes out cheaper than the 302.

That being said, the same issues with that 3.1" crank are there: finding it, getting it to fit, and making sure it can handle the power. I'd almost rather go with an aftermarket 3" stroke on a 4.125 bore block and just use longer aftermarket rods on stock pistons. It would cost more, but it might not cost more than finding that crank.

AxelTrap > GhostZ 09/15/2013 at 19:58

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The 283 through 64 had a forged 3.00 stroke crank but its small main journals. The back yard 302 was a 327 block with a 283 crank. Here is a link to some 283 high rpm net chatter, even some talk about boost. http://www.trifive.com/forums/archive…

GhostZ > AxelTrap 09/15/2013 at 20:02

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I'm not sure how easily I could get a 327 block (more difficult than getting a 350) but that saves me the issue of finding 327 pistons too, which I would need for a 350 -> 302. I'll have to go out and price 327s and see if they are worth the cost, but I also would rather stick with the larger journals... worth looking into.

dream build here i come > GhostZ 12/24/2013 at 01:09

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i know this is a few months old

for the 289 block why not machine it to use a 3.0" stroke. that stroke crank is plentiful. perhaps you can even find a "cheaper" crank like a imperfect (blemished) eagle rod crank for cheap. and then go for something like the dss rebuild kit 5.4" rods and pistons 0.03 over bore. its another alternative to going for the 2.3L 4cyl turbo 5.4" long rods for which i've seen somewhere that srs carries pistons for that application. if you are looking for a better rod/stroke ratio why not use the longest rod for the sbf 302

as for compression ratio 8.5 seems a bit low for n/a. why not shoot for 9-10:1 and if it seems too high down the road you can have a machine shop cnc your combustion chamber for a more desired compression ratio

lastly for added strength why not opt for a main support, ive heard of oem blocks safely pushing up to 650hp. plus there is the added feature of reducing harmonics supposedly to less than that of 4 bolt mains

shuvool > Frank Grimes 01/24/2014 at 14:07

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I missed this by a few months, but you wouldn't want to use a Chevy 305 for a high RPM build since the engine is undersquare. The longer the stroke, the faster that piston has to move in order to finish its entire stroke in a given time compared to a square on oversquare engine

Boss_289 > GhostZ 10/27/2014 at 11:45

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sorry, but your Ford 289 rod length is incorrect.

289 / Boss 302 = 5.155" connecting rod

302 = 5.090" connecting rod

Don't know where you got that rod length from, but it throws your entire eequation off. And No, no one offers an 289 (2.87") steel crank at the moment. However, any current forged steel crank can be underground or destroked. A forged steel 302 (3.00") Can be ground to 2.87" 289 crank. And 2bolt main blocks are fitted with 4bolt main caps routinely these days. Just saying

WickedWedge > GhostZ 04/20/2015 at 14:17

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I would take a good look at Chrysler 340 Small Block. wi

They rev like crazy, and make fantastic power. It’s aslo neither Ford , nor Chevy.

JSHarvey1961 > GhostZ 09/03/2016 at 18:28

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I have a “298" Ford in my 1965 Mustang. It is a 4.065" (over bore of a standard 4.000") with a stock 289 stroke and crank (2.87"). It will spin to 7,000 rpm (and does regularly). All we did was the following:

Balance everything to the absolute closest to perfection one can get. Top to bottom of all connecting rods, each piston separately, all the assembled piston rods (top to bottom and overall). Once this engines gets to about 1,000 rpm it sits absolutely still in the engine compartment, almost zero vibration. Polish the crank and “knife” the crank surfaces. Deck the block, mill the heads, put in forged pistons. Do a lot of porting work on the intake and heads. Line bored the block. Make sure the springs and valves are up to the task. (Note: It has much higher compression then you are aiming for - 54 cc chambers before the heads were milled, but then opened up very slightly with the porting.)

Few normal road going engines sound quite as fun as this one when it approaches 7,000 rpm. It has dual exhaust into “somewhat worn out “turbo” type mufflers (from the 1970s) with no exhaust crossover connection, so just straight pipes to the mufflers, and then straight out the back. It’s also a convertible so one really hears the engine.

I’ve never dynoed it, but I’ve left a lot of surprised cars in the dust at intersections.