468cid vs 454cid.. How much HP difference?
 

Made the discovery today that one of my remanned 330hp engines has been bored .060. I calculated that as being close to 468ci. This is a twin engine application, so I have concerns on balance of hp production. Will be mounting the other engine on the stand in a couple minutes and will see if it too has been bored. I would be suprised if it has been, but it would be nice.

That being said.. 2 questions:

1.) How much hp difference will there be between these two engines with equal components. As a straight percentage, this is 3.1% more displacement. If the engines were 400hp as 454s, this 3.1% would make the 468ci engine 412hp. Sound right?

2.) Will this difference be noticable in the boat?

BT :cool:

What kind of boat is this in?? I really don't think you will ever notice even 12 hp in a twin engine application, even if you were getting that extra hp. Simply changing the displacement doesn't necessarily add hp as you have figured it (using your 3.1% increase in displacement). If you can't use that extra displacement by changing other components (pistons, headwork, etc...) you will not see much of a hp increase. If it did, we'd all be boring out our blocks and adding pistons.

I disagree with that. Cubic inches has a direct correlation on horse power. Take this simple example, a 454 engine making 454 horsepower equals 1 hp per cubic inch of displacement. If all things were kept the same, a 468 cu.in. motor has to make 468 hp. If not, then what is the sense of stroking motors? Why don't we all run small blocks? The key here is "ALL THINGS BEING EQUAL"
Back to BTs' question---- I don't see how that slight amount of cubic inch difference will make a big difference. We have all seen identical motors make slightly different power on a dyno.

Thanks fellas. The boat is a 30' scarab. The other engine turns out to be .040 over, so the difference is now definately neglible.

I think Checkmate is on the money with the cubes question. Unless displacement is the bottleneck, it should be a direct correlation to hp. I also believe Waterfoul is on the money in that, that change alone without considering the system at large won't matter.

The real question is, is cid directly related to hp if all else remains relatively constant, and cid is not the bottleneck? I'm trying to figure out the linear quality of cid to hp.

BT :cool:

The other side of that coin:
If the cam and heads worked just right with 454 cubic inches, they may not work as well at 468. The 468 could even make less power. Lets put it this way, theres nothing you can do about it now so dont sweat it and enjoy the boat!

bluethunder,

With all components remaining the same, going from a 454 to a 468 you might see 1hp per added cubic inch---12-14hp. However, going from a 454 or 468 to a 502 things are going to start opening up! One of the major reasons is because a going from the 454/468's smaller bore size to the bore size of a 502 has a big effect on unshrouding the valves with the Big Block Chevy. That's why BORE NOTCHING is so beneficial to a 454 and can be to a 468 as well. The 502 bore size of 4.470" will not benefit as much from a bore notching job as a 454 which has a bore size of 4.250". Getting into the 502's larger bore size will already take care of the valve shrouding problem. My engines have a 4.500" bore and we only had to remove an extremely small amount of material for the bore notching that was done to my blocks because it's not near as critical as it is with a 454. Valve size has a lot to do with it too.

With the extremely small difference in power I wouldn't go to the expense of boring out one block just to match the other---I doubt you'll see it unless of course you just HAVE to do it that way. Tell you what, use the larger cubed engine that the power steering pump and pulley will be mounted to. With the little difference between the 454 and 468, mounting the power steering on the 468 will help balance the power and even the scales a little. :)

But if you can do yourself a cheap favor and do a bore notch job on each block---it's worth about 30hp!

Mark/KAAMA

If my math is correct, I have a 463cid and a 468 cid. Great idea with the power steering pump Kaama!

BT :cool:

I agree with an earlier comment. If a 454 makes 454 hp, then a 700 cu in motor with the same cam, heads, intake, exhaust, and carb will not make 700hp. The heads will have been maxed out way before the 700hp, as well as other components.

Let's say the 700 cu in motor only shows 600hp. NOW you have a second datum to plot a hp/cu.in. curve.

The curve won't be a straight line, but you can start with one and then throw a little curve to it that favors the low side.

Bottom line is, a 454 vs a 468, all other things being equal, won't show any appreciable difference on the tachometers. Relax.

Truth be known, last year the .040 engine was showing 100-200 more rpm over the .060 engine. May have been having a little carb problem though.

BT :cool:

Notch Boring
 

Kaama,

Tell me more about notch boring...are there websites about this?

Thanks,

Kirk

Pantera24, Tinkerboater and I bore notched my 454 (+ .060" for 468cid) and it was rather easy. If you take the head gasket and lay it over the bore, you now have a great template for bore notching. The gasket will be the same as the combustion chamber....including the path of the valves. Lay a gasket on your block, see how much steel is "in the way" of air flow. If you take some of this material out, angled toward the valve, you in effect straighten the flow of air. This is more important on the exhaust side.....you want to get all the charge out of the chamber on each stroke.

Hey Kaama, I went to Jim V's websight as you suggested and checked out the bore notching. It is hard to see, but I get the idea. Question would be, I also have a 509ci 4.500" bore. Do you think that bore notching this motor will give it any noticable gain for the expense. Also, is this something that my machine shop here in Cincy willbe faimliar with, or is this less common of a procedure?? Motor is most likely coming out in a few weeks for head wrok and dyno time, this would be the time to bore notch. thanks.

Allan4, When dealing with a 4.500" bore, your pretty much at the point to where the bore is large enough that bore notching is no longer necessary. I have 4.500" bores on my engines as well and they have been bore notched only a HAIR! Maybe 1/16" of metal has been removed. However, as I have previously stated, it will make a much bigger difference on a 454 which is about 30hp/tq of difference on the bore of a 454 bore of 4.250". Whereas on a 502 bore which is 4.470" or a 509 bore which is 4.500", it will NOT make that much difference because bores are much larger and no longer has an adverse effect of valve shrouding.

Pantera24-650HP, find a thread where "JimV" has made a post and click on the word "PROFILE" a page will pop up and then click on his homepage address. When his homepage pops up click on the word "Tech Tips" and a picture will pop up with some details underneath. You have to look hard for the bore notching process. Go take a peek! :)

I was wondering about the effect of a bore job and ran it on Dyno2000 software. I think I saw about a 3 HP gain.

JimV, did actual back to back dyno tests with just bore notching alone on Earhart's dyno and found it to be worth about 30hp/tq across the entire RPM range! At least that's what he told me and besides, you can do it yourself, takes maybe 1.5-2hrs to do it and only requires a die grinder, air compressor, and some other very inexpensive tools. You can't really lose unless you REALLY BOTCH IT UP!

Wow, that bore notching looks like a piece of cake, with a little patience and attention to detail. Other than the die grinder and some emery cloth, what else is needed? I'll need to do this with piston in place, so other than obvious issues of cleanliness, are there any suggestions to do a better job? Waterfoul, what kind of result did you feel you got from the job? How much negative impact would stock exhaust have on the effort?

BT :cool:

bt, you'll need some blue scribing ink, a scribe and you'll need to use the same exact head gaskets as you plan to use when figuring where how far to grind so that you do NOT go beyond the edge of the gasket. Obviously, you do NOT want to go any lower than the highest point of travel of the top ring groove of the piston within the cylinder bore.

Kaama, I have a pretty good carbon ring on the top of the cylinder, so I'll stay .060 or so above that for safety. Got my 1027 gaskets today, so scribing is good. Thanks for the help. Any more 30hp (free) tips are welcome!!

BT/Dave :cool:

I'm not sure what kind of gains I got from notching. I changed a LOT of other things at the same time. I did it at the recomendation of KAAMA, Crazyhorse, Tinkerboater, JimV, and a host of others with more knowledge than I have!!!

If you do it with the pistons in, stuff some paper towel in the bore to catch the shavings. And do each bore with the piston at the bottom of the stroke.

Mike

I'm with you waterfoul. I was thinking cleaning the cylinders with laquer thinner, then duct tape all around. I have all winter so wtf. Keeps me away from mamas jobs!!

Thanks for the help,

BT :cool:

Yet ANOTHER use for duct tape!! Gotta love Duct tape. Hmmmm..... sounds like a topic for a new thread!! Check the General Discussion soon......LOL!!!

Mike

Just for assurance...
 

bt, Just for a precausion, I think it would be WISE to PM Tinkerboater and ask him how he does it step-by-step BEFORE you begin to do any of these bore notching mods! Tink has done several of these and is a wizz at it! I think excersize a little wisdom to at least talk to someone who has done it a few times BEFORE you get started. That way he can help you to avoid any unforeseen pitfalls and make these mods a sucess!

Oh no... don't worry Kaama. I have it all figured out. Just got done with the second engine. Had a hellova time getting all the way to the bottom of the cylinder with the die grinder, but its done now. Had to go in from the crank side. Whew, what a job that bore notching is!! Boy I hope this works!! :D :D

BT :cool:

(PS, I haven't decided if I'm gonna do it yet. Still pondering. ;) )

Seriously though Kaama, I was just looking closely at this area on my blocks and they already have notches. More of a step I would say then what JimV showed. Is bore notching simply smoothing this step into more of a chamfer?

Thanks for the advice,

BT :cool:

KAAMA, thanks for the reply. Looks like I will bypass this effort. Later:D

Yes, the factory may have done it on your block(s), but it as you say more of a; "stepped" or more of a machined look to it and appears to be crude at best. Doing the bore notching with a die grinder you can make it wider and deeper and do a much better job by radiusing it out much better and making it a smoother transision of air flow.

Allan4, I understand. They're your engines---you can certainly do as you wish with them. You guys with 454's are always looking for a little extra power and this is a very good, inexpensive and reliable way of doing it without adding any complications to the mechanics of an engine. Anytime you can increase the correct kind of air flow within an engine without adding parts is like getting FREE HP. Of course it's your decision, I was just hoping to see you guys benefit from something like this and get the most out of your 454's. :)

Yes, making it into a nice, smooth, radiused chamfer. That's the goal here. Trust me, it's easy!!! Just remember to use the HEAD GASKET you're going to use as a template.

Mike

Do you think it's even worth doing on 468s ?
Free HP sure is nice !!!!!!1

Since my engines already have the fly cut notch, and because of the .060 over, do you guys still think it is worth 30hp? Trying to weigh the risk to potential benefit.

BT :cool:

birdog and blue thunder, not trying to be short here, but at this point it would probably benefit you guys if you went back and RE-READ all of my posts within this thread.

Blue Thunder, The "fly-cut bore notch" that comes from the factory is CRUDE at best and I have already addressed it in a previous post within this thread.

Birdog, yes you will definately benefit from a bore notch with a 468 and I have pretty much already addressed it in a previous post within this thread.

Not convinced yet? Call "JimV" at (616)735-0800 9m-5pm. EST. Or PM Tinerboater and discuss it with him. It's a true and cheap horsepower maker! :)

Even at an over-bored 468, you'll be surprised how much steel is still "in the way" of airflow. As stated above, my motor is 468 and we did bore notch it.

Can anyone post a picture of what the block looks like when properly bore notched? How much material is taken out with this process? Is the material that is removed enough to cause a lose of compression by enlarging the cc's of the combustion chamber?

I have heard of this process but never actually seen it done before. This thread has started my interest in this again.

Well, here is the first of 16. Only 15 to go. Is the quality ok? Any further suggestions? Hope the answer to Checkmates compression question is negatory. As you can see I have flat tops and running what are now 115cc heads. Don't want to loose any compression.

Thanks for the help,

BT :cool:

That's what I wanted to see!! Good picture. Those reliefs don't appear to big, maybe not even enough to effect compression.

BT;

Can you measure the cc's of the cylinder before and after your relief work? That will tell you the real story on compression.

I don't have a method to cc Checkmate. I am sure this is an unmeasureable change in compression. Particularly because ther was a step notch already there from the factory. The one I have done was quite easy, but I will say somewhat nerve wracking. Hopefully as I go along I will become more skilled.

If you want to see a skilled notch job, go up a couple posts to where talk was about JimVs work and where to view it. Those are some sweeeeet notches.

Another first today was that picture. Never posted a pic before. Bought the wife (ie me ;) ) a digital camera for christmas. I'm gonna like that!

BT :cool:

Another notched pic.

Hey KAAMA, it's not that I do not want to, but I already have 4.500 bores and you seemed to think that little will be gained by notching. Is that right?? No need to spend the time or $$ if the reward will be unoticeable. Thanks, A4

Allan4, yes that is correct. The larger the bore size the less you will benefit from a bore notch job. Although I DID ask JimV to bore notch my blocks with the 4.500" bore size, but he only did just a little. He did it because I was running a 2.300" intake valve when a 2.250" intake valve is usually used on a 4.500" bore size. Next fall I will have my blocks bored out from 4.500" to 4.600" which will really unshroud the big 2.300" valves I now have.

The Merc HP450 engine which is a 454 cubic inch engine would really benefit from a bore notch as well because I think Merc used a 2.250" size intake valve in that particular engine which is kinda BIG to begin with. Bore notching would help unshroud the intake valve well.

Blue Thunder, Boy!.....I...I say boy! Ya doin' that ----I say ya doing that all wrong now son, ya heya?

Just kindin--- that bore notch is looking pretty good on your first cylinder there son. Remember, you can go out to within about 1/16th of an inch or so of the gasket you are using. If you look at JimV's example as he has pictured, it shows that he followed the gasket pattern closely and removed as much metal as he could for optimum air flow. N0 beer, coffee or cafein----All you need to do is good/accurate prep work and keep a steady hand and you'll make it home! As long as you are using the same model (part #) of head gasket and do not exceed its bounderies you'll be fine. Same goes for the TDC of each piston with the top ring within the cylinder bore---if you go too deep past that top ring and EEEE BOMBRA SEEE.......boy, you gonna find yourself in THE LAND OF NO RETURN SON!-----GULP! :et:

Tinkerboater knows his bore notching. He is also one of the fussiest people I know. He has done this to assembled shortblocks (his own) so he would be able to give you good info on best way to keep things clean. I will send him a PM to let him know about this thread.

Not sure on this but it seems like used head gasket is prefered.

Wow Kaama, you scared the chit outa me... but I must say, I do deserve it! And thanks backformore for posting that ferrari pic next to my hugo pic. :D

I am using an old gasket and it is helping a lot. I only spent about 10 minutes on that notch, so I will clean it up to look more like the ferrari notch tonight.

No beer eh? HMMM, dam.

BT :cool: