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 Post subject: Engine upgrade
 Post Posted: Fri Nov 18, 2011 5:04 pm 
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I am going to try to step my stuff up over the winter and would like opinions on a couple of things. I would like to get my 2300 lb car through the 1/4 in somewhere the 8.30 range. According to the calculators it will take somewhere around 850 HP to accomplish that and I think that may be a little low. I'm looking at going to a 420 inch combination maybe a bit bigger depending on how thick the cyl. walls are. This will be a Ford windsor based SVO 9.5" block 4.090" bore 4" stroke. Right now it's 4.030 X 3.625 with just barely over 14:1 compression ratio and some very old C3 heads.

Heads-I am looking for some D3 heads so if anyone out there has a source let me know. The heads I have on it now flow somewhere around 340 and I understand the D3s are over 400. I'm thinking around 15:1 CR.

Crankshaft-For the last 12 years I have been running a Scat billet crank and I couldn't be happier with it. So Scat would be my 1st choice for a crank. They offer 3 different weights of forged cranks with the billet being over 3 times the price of the heaviest of the forged cranks. The tech guy at Scat said the HP I want will be at the limit of what the forged crank should handle so I'm torn between saving $2K and gambling on the durability of the forged one. Currently it's internally balanced and I will keep it that way.

Camshaft-Right now I use a Comp .714 282/292 roller with 108* lobe separation. I was told the intake lobe is a hi tech and the exhaust is hi rpm, it's supposed to be easy on the valve train. I talked to a tech guy at Comp and he said this cam should like the bigger CI and it may have been a little big for a 370.

I'm thinking the bigger inch motor will want less RPM than what I turn it now but I don't know if it will be enouigh to change the rear gear? Right now I shift @ 8,200 and cross the 1/4 at about that. Keep in mind this is a stick car.

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 Post subject: Re: Engine upgrade
 Post Posted: Fri Nov 18, 2011 5:36 pm 
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850 HP in a manual car at that weight will get you 8.30's and faster. Thats what we run with a heavier car (2424lbs with driver) and auto with that power.

I would change the crank. If they say it's on the limit at the power you want then you have to consider how your going to make that power as to what its going to do with the crank. What Im getting at is you have 4" stroke and going to go with 400 CFM heads. Thats going to make a lot more torque and its torque that bends and breaks cranks. High rpm - small torque for the same HP is easy on the crank. Thats not going to be your engine.


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 Post subject: Re: Engine upgrade
 Post Posted: Fri Nov 18, 2011 7:06 pm 
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Why not get an Iron Eagle block and bore it out to 4.155? 434 ci should get you to the HP level that you want. Bob


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 Post subject: Re: Engine upgrade
 Post Posted: Fri Nov 18, 2011 8:05 pm 
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shrinker wrote:
Thats going to make a lot more torque and its torque that bends and breaks cranks. High rpm - small torque for the same HP is easy on the crank. Thats not going to be your engine.

Thanks, I hadn't thought of that.

scoop wrote:
Why not get an Iron Eagle block and bore it out to 4.155? 434 ci should get you to the HP level that you want. Bob


It's a SVO block and there might be enough material there for that size bore. I plan on tearing it down over the weekend and having it sonic tested to see how far it will go. Found a guy about 45 miles away that can test it.

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 Post subject: Re: Engine upgrade
 Post Posted: Fri Nov 18, 2011 10:56 pm 
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FYI, long arm in that block isn't going to want as much RPM as you've been use to. My 434 is about done around 7700 and these heads flow 377 and 256.

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 Post subject: Re: Engine upgrade
 Post Posted: Sat Nov 19, 2011 11:38 pm 
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imo,...I wouldn't go the 4 inch stroke route. I'd stick with a 3.750 or 3.875 stroke. With the larger bore. I'd look at trying to twist this thing up in the RPM more. I'd go with a bryant crank with the smallest journals he offers. Light rods,...GRP would be my choice. I'd seek out a spintron and spend some money towards cam and valve train development. Valve bounce causes a huge drain on the hp.

Would have to talk more about the rest of your combination to know where else you need to look. vacuum pump, dry sump, oil pan, carb choice, intake choise,...and a ton of other stuff.

Myself,...I don't like anything over a 400 ci engine in the small block package. For a number of reasons. But the biggest one is that you just can't get the heads to support the rpm needed to do what you wanting of them when running much over 400ci. Engine rpm, mixed with alot of other variables, will result in more rear tire speed on the top end.

I realize I'm not properly expressing my opinions here. But I am not an eloquent assembler of words, especially in text form. I think you know what I mean. You have my number if you want to talk more about this. Not that I am any smarter then any else around here. Just another guy with an opinion. ](*,)

Don

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 Post subject: Re: Engine upgrade
 Post Posted: Sat Nov 19, 2011 11:44 pm 
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If you could move the whole torque curve you're making now 500-800 rpm higher then you are turning now where would you be? Just a thought... :-k

Don

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 Post subject: Re: Engine upgrade
 Post Posted: Sun Nov 20, 2011 1:25 am 
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Chuck, what valve angle are the D3s? Ive messed with a buncha 23dg Chevy heads that would make way more power on a big motor (406 to 422) when I made the ports bigger, but they didnt flow any more (335 cfm or so). I had three 23dg, 406 inch motors that made over 800 hp and peaked at 8100 and another that peaked at 8200. My 422 inch sb2 now peaks at 8300 and makes another 100 hp. With 3.875 stroke, 4.162 bore and 6" rod it really wants to go to 9grand! =; If the D3s are close to the sb2s then 422cubes wouldnt be any problem at all. I never liked a lobe sep that tight, 111 to 112 with about the same duration would be my choice. And Comp has WAY better lobes than those old Hi Techs imo.


Denis


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 Post subject: Re: Engine upgrade
 Post Posted: Tue Nov 29, 2011 6:01 pm 
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The sonic test didn't tell me what I wanted to know so it looks like I'm going to have to buy another block. This one is only good for 4.060 safely maybe a little more but definitely not 4.090. I don't think I'm going to have the money for a block and a new crank but the block I'm looking at should go at least 4.165. The guy that will be doing the machine work said he has one right now that's 4.185 and he said there's room there to freshen it up a couple of times. So if I go with a 4.165 and stick with my 3.625 crank that will get me just a hair over 395 inches. Tim (machine shop guy) suggested in going with a 9.2 deck instead of the 9.5 that I have if I'm going to stay with the 3.625 stroke. He said it should work and would perform better. I can go with the Dart sportsman block for the 9.5 deck but would have to spring for another 400 bucks for the 9.2 because it's only available in the Iron Eagle. Tim said he didn't think there would be that much difference in the performance and I'm thinking if I go with the 9.5 block there's a chance I might be able to add a longer stroke down the road. Because I'm switching heads I have to buy an intake anyway so there won't be any real difference there.

Axe, I can't seem to find any info about the valve angle. I did learn today that although the C3 valves are at different angles they are not canted but the D3s are. I have heard a decent D3 will flow in the 420 range and no less than 400.

So what do you guys think? Will this combo benefit much from an extra 1/8 to 1/4 inch of stroke or will it be easy enough to achieve the performance I'm looking for with the shorter stroke? Would the performance difference in the shorter deck block be worth it? I have to buy a block and pistons anyway and I think I can swing this but if the performance gain is going to be disappointing I think I'll just put my junk back together and wait.

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 Post subject: Re: Engine upgrade
 Post Posted: Wed Nov 30, 2011 2:39 pm 
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I would go with the 9.5 deck, might hurt it a little but not worth handcuffing yourself later. Its a
shame you cant get a crank too because I bet those heads would love 420cid if they are sized correctly.


Denis


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 Post subject: Re: Engine upgrade
 Post Posted: Wed Nov 30, 2011 4:59 pm 
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I would go with the taller deck. The machinist is suggesting that the necessarily longer rod wont work as well but thats not a simple problem that can answered in a simple way like that. The rod choice has an effect definitely but not at the level that your going to be at. Its far more important to concentrate on other deign aspects and their effects on tuning needs. Most times people arrive at rules of thumb or observations of things like say the rod ratio without doing sufficient analysis of what is actually going on in the combustion. For instance a longer rod will dwell the piston more at the top range of the stroke and that creates a different environment for the flame to grow etc. Thats what matters, and thats totally dependent upon so much other stuff its not funny. Quite often in racing you do one thing that takes something forward and send some other things backwards and you end up loosing out. So its important to ISOLATE factors to understand them. Its surprising how much that is not done, even by scientists, let alone the Climate changing mob.

I figure that if your going to run the engine around its max torque in a manual car towing a massive trailer then Id go with the shorter rod to reduce detonation tendencies but this is a race engine and it will be higher up in the revs at max HP range (eg lots of little bangs )rather than max torque (eg highest cylinder pressures with a few big bangs). Its the big bangs that break stuff.


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 Post subject: Re: Engine upgrade
 Post Posted: Wed Nov 30, 2011 7:58 pm 
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If it was my money, I'd keep it like it is until you can afford to upgrade the block and crank at the same time.

If you go with a different block now with the same crank you will end up buying either pistons or rods again when you buy a new long stroke crank later.

When you buy the block and crank I'd get the 9.2" deck block. I'm not sure how big of a motor you want to build but that will make a 436ci (4.165"x4.00") real easy. It will weigh less than the 9.5" and help keep the weight lower in the car. A SBC 434ci fit a 6" rod with a 9.0" deck ht. With a 9.2 you can fit a better piston/ring pkg. That'll make 900+HP with good heads flowing 420cfm. Not sure how much stroke will fit in one of those blocks.

Rick


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 Post subject: Re: Engine upgrade
 Post Posted: Wed Nov 30, 2011 9:35 pm 
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rick360 wrote:
If it was my money, I'd keep it like it is until you can afford to upgrade the block and crank at the same time.

If you go with a different block now with the same crank you will end up buying either pistons or rods again when you buy a new long stroke crank later.

When you buy the block and crank I'd get the 9.2" deck block. I'm not sure how big of a motor you want to build but that will make a 436ci (4.165"x4.00") real easy. It will weigh less than the 9.5" and help keep the weight lower in the car. A SBC 434ci fit a 6" rod with a 9.0" deck ht. With a 9.2 you can fit a better piston/ring pkg. That'll make 900+HP with good heads flowing 420cfm. Not sure how much stroke will fit in one of those blocks.

Rick


I'm with Rick,... I think you'd appreciate the 9.2 more.

Don

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 Post subject: Re: Engine upgrade
 Post Posted: Fri Dec 02, 2011 4:26 pm 
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What do you guys think about the 7mm intake valves? One guy says he doesn't trust them in a drag race application but I have another guy that claims they are fine. The 2nd guy claims that the valves are so light you don't need much spring pressure to close them, he suggest around 240 lbs. on the seat. He claims he's ruining a similar set up himself. I have always run more than that but what he says makes sense. It will cost a little more to go with the 5/16 intake but not enough to make a difference and the exhaust are already 5/16.

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 Post subject: Re: Engine upgrade
 Post Posted: Fri Dec 02, 2011 7:32 pm 
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Alderman was running 7mm valves back in the 90s. I think they eventually went back to the 5/16 stem.

I think some time on a spin tron would be worth your time and money. I think it can be a better tool then the dyno for dialing in the upper end along with the cam. I think that's where you'll find the sweet spot of spring pressure. What rocker ratio are you running?

Don

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