Speed secret # 5

[Kevin Price]

Total ci is 417 with a 4.125 bore, 3.9 stroke on a 6 inch rod. I went with the SVO 9.2 deck block simply because I was getting a run-a-round on the 9.5.

I am running the Chevy journaled rod from Oliver. Please don't tell my chevy friends though, I hear enough from them about the trans.

[jim_howard_pdx]

Those chevy guys are losers.

When we beat them, they always have an excuse and eventually fall back to the..."but you used this chevy part or chevy idea to beat me"...

Powerglides make for awesome and consistent bracket trannies.

LOL, just tell your chevy pals that a well prepared powerglide has NO chevy parts left in it. Nowadays, even the case and control valve are aftermarket pieces.

Man I love your engine... The extra .2 deck height would not really give you enough room for a meaningful road stretch. Your rod to stroke ratio would go from 1.58 to 1.59.

I will share one thing with you Kevin, You should consider running a 3.25 inch stroke with a 6.75 inch rod for a 2.077 rod ratio 329 cubic inch engine.

With your heads and NOS, and the less weight your car can run using the smaller cubic inches, you should be capable of running all the way down to 8.2's or 8.3's.

Just because you don't see a bunch of guys doing this doesn't mean it won't work.

Most speed shops see increased displacement as the way to gain torque, but the strokers end up with these low rod ratio's like yours and then your torque range is short and with a tight peak. Then you have to add weight to the cars to compensate for the higher cubic inches in your brackets.

So a 2.077 rod ratio 329 allows you to build more torque, wider torque, and cut the weight down on your vehicle. This makes for a screaming ride! And a Chevy block will not allow this type of long rod ratio, so you can win your bracket year after year after year.....

Just some food for thought....

I just want to know what Erik4 Nitrous is doing to hit 7.5 ET's. He is going to need a pro-stock chassis to run with this monster. I think he said the engine has dyno'd at 1100 HP. TOO MUCH!!!!....I gotta get one of these.....

[Eric4Nitrous]

I plan on running mid to high 6's not 7's.lol I've already been in the 7's My new car is going to be a pro-stock style car. Motor dyno'd at 1780+hp on three stages.

[ultraflo]

Rod/Stroke ratio is a highly debated topic... some believe that rod/stroke ratios are meaningless when it comes to total power output/potential. I tend to keep an open mind on the subject, but when I first read about running a longer rod, it made sense... more dwell at TDC for a more complete burn. There was a good thread on this over at hardcore50.com some time ago...

FWIW, I used a 5.400 (1.8:1) rod in the stock block'd 306 I ran this year. Going to run the same rod length in the R-block 306 also.

I'll be happy with around 750hp to the wheels... for awhile anyhow. Not sure I'd know what to do with a setup that approaches 2000hp... soil my draws, prolly.

[jim_howard_pdx]

Eric I wish you good luck, but like the honda engine crowd, I tell them yes you can have 600 hp but for how many runs.....

Running 6's would be a much easier job for a big block and NOS. Bigger stronger parts, bigger stronger crank, bigger beefier mains and blocks.....

You are putting that poor small block on the absolute edge of its envelope. Or is this a 460 based engine you are working on for the 6's?

I expect it to take you a while to dial this set up. What transmission will you be using?

If the parachute doesn't deploy, how do you plan to stop the thing?

Man, my mind is swimming with all the stuff it takes just to drive 7's safely.....

You go....rocket man Eric 4 Nitrous!

[jim_howard_pdx]

Ultraflow,

What I can tell you about rod ratio is this, every race engine I have ever built to run 180 mph or faster had a minimum of 2.05 rod to stroke ratio, and most had 2.1 to 2.2. After 2.2, you actually do better adding extra displacement since the burn event is pretty much over in about 40-50 degrees of crank movement.

So for the Chevy crowd running 1.5 rod ratios, my 351 at 1.78 comes out of the hole much faster and revs faster too. They have trouble building the low torque, in fact their torque curve tends to be highly peaked.

Like I said, most speed shops do not know how to build a world class race engine. When Trans Am cars were limited to 302 cubic inches, we were well into the 178 mph range on these cars. When NASCAR set their limits to 355 cubic inches, almost every team was hitting 190-210 mph in the straight aways with a two barrel 500 cfm carburetor. You gotta know they were running long rods.

Hope this helps...

My 428, when it made the finals, only lost two races. One was to a 500 cubic inch chevy, and the other race was to a 426 Hemi. Both beat me by less than 48 inches at the finish line. At this proximity, it is launch quality and reaction time that determines the winner. I ate a fine cuisine of short rod big blocks in my time, and they came up wanting..... Even the 427 Fords couldn't hang with me in my bracket. (short stroke, short rod, huge pistons, this design is called "over square". It does very well on track courses where the rpm capabilities of the 427 allowed it to dominate until the 428 and then the 429 replaced it.

The 428 was a little bit of magic with its 1.88 to 1 stock rod to stroke ratio. There are very few engines before or since with these types of ratios.

Building a 10 second car is getting relatively easy. Like I said in different thread, it is getting to be like building with lego blocks.

[7000rpmisheaven]

This is new to me but I think I understand what you are saying. Would it be possible to run a 302 crank in a 351 block and just use longer rods.

It sounds like a cool idea and even something that I might want to try out. But the 15k motor you suggests is well out of my reach. Using a 302 crank in a 351 block sounds much more practical. In comparison would a long rod 302 make more power than a regular 351.

[Eric4Nitrous]

Big Block?? bwahaha who needs a big block to go fast? My motor is just a little ol windsor. Tranny is a liberty clutchless five speed, and if the parachutes don't stop it..then i'm hoping my strange brakes will.

[drtbiker]

or u could try to put your feet out lol na maybe safer to jump out

[Eric4Nitrous]

haha i think i'd rather jump

[vetteeatr]

Ok I got 2 questions.

1. Ok This seemingly is jsut plain ingenouis even if you didnt officially think of it. Too good to be true. Not that im saying oyur lying a bit though. I jsut woudl think there would be come downfalls to all that great power gain and efficiency. Any you can think of?

2. As someone metioned earlier 15k is pretty pricey for oyur average car guy or at least for me at the moment it is. What woudl be a budget buildup on a 351 form a 69 or 70 stangf with the stronger block to get a longer ratio what about a 5.0 Block?.

Using any rod pistons and crank from any make of car.
Doesnt have to be optimal but if you could maybe somehow work something out with a few forged pieces that are allready slightly diffrent for other motors allready forged it would be alot cheaper then machining everything.

Thanks

[vetteeatr]

Is there a reason that you do not try to make a longer ratio or is it the limitation of the block design?

Also how can nascar do those high ratios do they got special blocks with diffrent dimensions?(Sorry know not a thing about NASCAR)

[jim_howard_pdx]

No

a 302 crank and a 351 crank have different main journal diameters. The 351 uses a 3 inch main journal which puts enough meat on the crank to support 1000 hp or so.

What you do is offset grind the 351 Windsor crank, usually a forged crank, to get down to the destroked point where you can add the length back to the rod. On a stock crank, I usually go for a 332 cub inch engine. With a custom forged crank blank, I can get it down to a 306 or 312 and hit the 2.2 rod ratio I desire.

On a 351 piston, it is relatively easy to get a forged piston with a .5 inch taller pin location. Then take a quarter inch off the 351's stroke, and you end up with a 6.695 rod. I just bump the rod to 6.7 iches and measure to maintain a minimum .39 quench on the deck. Some modern race engines are building zero deck engines, so the piston actually pokes up through the head gasket space, but this is very dangerous, and I do not recommend it for us common folk.

With any rod, over time the rod bearing cap will elongate into an oval, and when you put that .001 inches back into a zero deck height race engine, you get catastrophic failure.

I believe a stock 351 crank, nodular iron can be cut to 3.2 safely. Perhaps lower, but I really like 332 engines, so this is where I destroke a nodular cast iron crank. Then go with the longest rod, shortest piston you can fit. 1.98 rod ratios are easy, 2.05 to 2.1 come at a price, the oil control ring land will be machined in the pin's boss, so you lose oil control. Ok with racing, not as ok on a street engine.

My extra secret to you is this. At 5,000 rpm the spark plug is firing some 30-36 degrees before top dead center, so as the mixture is compressing, the spark creates preignition, a kernal that must get the air fuel mixture to burn as fully and completely as possible. With a long rod, the piston is higher in the bore at 36 degrees btc. See why you build more torque? You have more cylinder pressure, greater quench, and less chance for detonation because the mixture has been compressed more at 2.2 than at 1.5.

Plus the longer rod accelerates the piston faster up the bore during the compression stroke. This creates more mixing of the air and fuel in the cylinder. Then at the top of the stroke, the long rod slows down and "dwells" the piston LONGER than those short ratio engines.

I should have told Ultra flow this in my response, but I wanted someone to say WHY would your 428's 1.88 rod ratio almost double the torque of that 350 small block engine with only 78 more cubic inches????

This is the reason. When the spark ignites, the piston is higher, quench is tighter, cylinder pressure is higher and THEN we get the cherry on top.

The cherry is that the piston "dwells" longer at tdc than the short rod ratio engines. So the fuel is burning and the piston is parked there as cylinder pressure goes astronomical. The pressure exerts far move leverage against the piston and crank.

See why a NOS or charged engine would put out 1700 horsepower with 420 cubic inches (like Eric 4 Nitrous's Missle Car!) Only his rod ratio is short, so he has to use three stages of NOS to compensate!!!

And the best part is yet to come. Now as the piston falls away during the power stroke, more cylinder pressure is being exerted BUT the long rod engine pulls the piston away slower at top dead center, then very quickly as you move to center bore. Since your pistons are firing 45 degrees apart, this means that the extra torque is multiplied by a factor of 8. So if you are building 10% more torque in one cylinder, it gives you 80% more torque at the flywheel or pressure plate.

You get all this for FREE, other than the cost of admission.

You use less fuel to get more torque. You get a lot more torque at every rpm range. You get mind altering results with NOS, Turbos, or Super Chargers, and you get less chance of detonation to boot.

That is why the 302 Boss ran 224 mph at Bonneville. It had a 351 Windsor block, and it had a custom forged crank that let us offset grind to a 3 inch stroke. Titanium rods and pistons kept the reciprocating energy low. Compression ran 11.5 to 1 and for the bonneville run, my Pantera buddy ran gasoline only. Later he added direct port injected NOS, and eventually went to dual turbos. I helped him with the destroked block, piston shape, head work and bolting everything together. I also helped him with the direct port NOS injection.

I am glad he had some money, cause it cost 100 grand to build this race car. 25 grand in the engine alone.

So if anyone tells you the jury is out on whether long rods are better than extra displacement tell them both sides are right. BOTH methods work. I can build a 10 second car either way. But the long rod engine will have a broader and taller torque curve, it will consume less fuel to build the target horsepower you need, and it will run without detonation. It can tolerate more advance and can take it sooner also adding to the torque levels of your engine.

So now you know the physics. Next time you build an engine, set about to maximize that rod ratio. You will be happy that you did. 1.9 is the minimum rod ratio I would want to run on any of my race engines. Next time I rebuild by 358, or build a new engine, I plan on building a 2.2 ratio engine. It may be a 460 block, or it may be a Windsor. I just want something to play with that when boosted by a Vortec or Novi blower will make 700-800 horsepower, idle like stock, get 16-18 miles per gallon, and run like a triple crown winner.

You can have your cake and eat it too, if you take the time to make it a long rod engine.

[jim_howard_pdx]

To build a 400+ horsepower engine, plan on spending at least 2,000 to 2,500 dollars on a block. To do a long rod, tall deck Windsor, you might not spend any extra money, but you will need to measure everything twice, check clearances and the like.

A 1970 351 Windsor core would be about 50-75.00 A full shortblock around 250.00. You do not need the full shortblock.

Have the engine decked for straightness and to square all 4 corners. (150.00). Take the minimum material necessary to accomplish this. Usually about .002 to .01 inches will need to be removed.

When the bore is enlarged, try to center the bore down the cylinders. Most blocks are bored off center. Try to get these centered if possible and reject any block that can not tolerate a .030 bore with a minimum of .18 cylinder wall thickness. I have punched holes through thin cylinder walls on an engine before.

Bore and cross hatch with a deck plate. Cost about 250.00.

Line hone the mains. Cost about 75.00 to 150.00 Have then chase all the bolt holes with a bottom tap, or do this yourself. Have all oil gallery plugs tapped for screw in plugs. NO PRESSED IN PLUGS.

Have all oil return holes chamfered for easier oil return. Some of my buddies swear by painting the inside surfaces for oil return. I am still on the bench on this one. I cannot see any difference on the dyno or at the track. I leave this one to you.

If using a stock crank, have the main journals cut .010 undersized to what ever they are. Maximum is .050. I just cut the minimum to keep it straight. Chamfer the oil holes. Have them offset grind the crank to 3.2 or 3.25 depending upon your pistons. I like to use extreme light weight Probe pistons or J&E custom slugs with .5 inch higher pin location and ring lands sized for thin racing rings. I like the Child and Alberts zero gap units. Slugs and rings will run about 700.00 The crank will run between 500 and 700 dollars for a stock nodular iron, and 1,000 to 1,500 for a forged steel crank. Check Summit out, they may have some ready to rumble for a great price.

I use an Aluminum Chrysler rod with Chevy journal and pin dimensions. 1.64 inches to 1.7 inches and alter the stroke to match the deck height. So I do try to get the most cubes I can with the cheapest parts I can. With good ARP wave lock bolts you will pay about 700.00 with pin and mounting to the pistons.

I like to get the pop top or dome piston 12.5 or 13.0 to one compression pistons. I then smooth them out completely aiming for .060 quench. .080 max along the top. I go 0.12 near the spark kernal to get a great preignition event. Coat your piston tops yourself (about 125.00, or pay up to 40.00 per piston to have it done (320). Or leave it raw. I like them coated but let the RULE BOOK decide this. Many classes do not allow custom pistons, or domed pistons, or coatings........

Use studs and a girdle, windage tray, crank scrapper, and high volume oil pump. 300.00.

Bolt it together yourself. With a good 400.00 harmonic balancer and new pressure plate or flyweel your short block will come in at about 3,000.00. Not bad for a set up that should deliver safe power to 800+HP with only a cam change.

The cam I leave up to you and your driving ambition. I like Cloyes true roller timing chains. They have an infinite adjustible model but I usually buy their street roller set up. Replacement chains every 100,000 miles cost you 17.95. Cannot beat that guys.

These are available in under size chains to take up the slack from the line honing. I have them aim the line hone for .010 crank to cam shortening, then order a .010 shorter chain!!!! This maintains your timing!.

Bolt on some Trick Flow street heat or R heads, a good intake set up, a good distributor and MSD or Crane ignition box and you are set to go. All together the engine will run less than 5 grand, and with a super charger it will run under 8 grand.

I have built 8 grand engines for kids to run Honda's at the 12 second et bracket. Here is an 8 grand engine that will build 650-700 hp and run easy 10's with slicks on a 3300lb Mustang.

Put some money in the transmission, clutch, and rear end. Set up the suspension for bite, and 9's can be yours from the very same engine. Plus you drive it home from the track dusting off unsuspecting turbo porsches JUST FOR THE FUN OF IT.....CAUSE YOU CAN!

[Eric4Nitrous]

My rod isn't short I don't use more nitrous to compensate for having a short rods. I use more nitrous to make more hp and to keep up with the competition.