Approximate HP help . . .

I was wondering if anyone could lemme know what the approximate HP, at the flywheel or wheels doesn't matter which, for an engine with these specs:

Stock dual relief, full flowed case w/first line bore.
76mm balanced crank w/stock rods.
94mm pistons/barrels.
Lightened flywheel.
Rear balance pulley.
Engle 120 cam w/straight cut gears.
Lightened SCAT lifters.
40x35.5 valves in 040 heads, HD single springs, titanium retainers, port on exhaust only.
1.25:1 rockers.
36mm oil pump
Dual Kads with match ported intakes.
1.58" exhaust header w/single quiet pack for back pressure.
Mallory distributor and coil.

This is up against a highway geared Pro-Street transaxle with a 4:12 R&P and Bus forth.

The little Fiat is coming in at about 1,200 pounds and I was wondering what the power/weight ratio would end up being. An approximate number for the horsepower would at least get me on the chart, you know?

Thanks ! !

TC

I would say around 125-130. And nice torque with the 76mm crank.

Mike

I come up with 95 to 100 hp, whatever it actually is, the HP to 1,200 lb weight ratio ...she'll scoot right along ~

According to every post that I read on The Samba, the Kads alone ought to bring it up to 90hp, Add an 009 and a $40 extractor and I should be pushing 120 easy.

According to the experts.

On The Samba . . .

So any way to get it up a bit more? Maybe a set of bigger venturies and jets for the Kads? Different cam? Bigger header?

Thanks

How many ccs w/ the 76x94 mm crank/pistons? That should be the first and most important clue.

TC... If you want more power...put the rest of the money into heads. You have good displacement already, headflow is the next place to gain hp. Also, ditch the 009. The advance curve sucks. (Depending on the budget of course)

Mike

Here's the "simple" formula for figureing up 4 cylinder (or less) displacement
This formula can be used with metric or inch measurements

bore x bore x stroke x 3.1416 = displacement
Evil's proposed engine will have 94mm pistons and a 76mm stroke

94 x 94 x 76 x 3.1416 = 2109.69

For anything greater than 4 cylinders:

bore x bore x stroke x .7854 x #of cylinders= displacement

An example: a Ford 302 CID engine had a 4.00 inch bore and a 3.00" stroke

4 x 4 x 3 x .7854 x 8 = 301.59

For right now, I've already spent my head budget on the medium valve low tech heads that I have. I could have the exhaust ports extrude honed easily enough, and expose more of the stem and less of the guide for flow, but I've always heard that you shouldn't mess too much with the intakes on relatively small valve heads. Not sure, but . . .

Would a pair of Magnum 44s make a big enough difference to the horse power? I can get a great used pair for some coin plus work if it's really worth it, lemme know would you? With such a short stroker, those heads might be better served by a 78mm or larger crank. Not for this engine, but maybe another next year.

MAYBE a cam change? I have a VZ15, but I kinda don't want to open the case back up unless it's totally worth it, you know?

The current distributor is an NOS Mallory dual point that will end up with a Jacobs electronic ignition module installed. I've been working on a Vega HEI distributor that will go into the engine eventually. The last bit of surface machining needs to be completed and it'll be all set to go. Some folks have been working on using the fuel injected Type II distributor with German 009 advance springs installed as a good alternative for low budget racing. I have all of the parts and info, but I'm waiting for someone to install theirs and report back. Other than these or the 010, any other suggestions for a mechanical advance distributor that I might look into?

I thought that it would end up being around 2000/2100, but didn't know exactly, thanks for the math.

Anyway, thanks for all of the info ! ! The present HP estimates are certainly encouraging. I'm just wondering what the additional gains vs coin might be?

TC

It is a diminishing returns sort of thing. The last 10% of gain can take 90% of the budget. I think I saw some pretty savvy recommendations made in another thread recently about where to get the most bang-for-buck. Cubic miilimeters and breathing is what it is all about.

Oops, I gave you some bad information The following sentence contains an error
Here's the "simple" formula for figuring up 4 cylinder (or less) displacement
This formula can be used with metric or inch measurements


It should read:
Here's the "simple" formula for figuring up 4 cylinder displacement ONLY
This formula can be used with metric or inch measurements

The second part where I give an example of a Ford V8 302 is used for anything other than (4) cylinders Which means a 1 cylinder, 2 cylinder 6, or even your Ferrari 12 cylinder etc etc

Agreed, most power gains will be found with better heads. But given the existing heads' limited upper RPM intake flow, you might want to step down to 1 1/2 headers to better compliment the usable RPM range.

And BTW, needing exhaust backpressure is a myth. You don't want backpressure in your exhaust. The reason you want to keep your header diameter small is to keep the exhaust velocity high. High velocity leads to high scavenging for better cylinder filling = more torque/power. But that must be balanced by the need to have a large diameter for ultimate flow capacity at high RPM.

Your displacement formula works for any number of cylinders, including 4. But in metric, don't forget to divide your displacement figure by 1000 to convert your millimeter bore/stroke measurement to cc's. Or by 1,000,000 for Liters.

bore x bore x stroke x PI/4 x # of cylinders = displacement

Thanks gang!

For this engine, I'll stick with the parts that I have in place, although I'll search out some distributor alternates and substitute there for sure. I'll also drop the exhaust size down to 1.5" and give it a try as well as trying the the 1.65" header.

The car is light and tiny. Like a "said" it comes in pretty close to 1200lbs with a 78" wheelbase and 52" track width.

I was hoping for a 100/120hp engine and something around 10/11 pounds per hp weight to power ratio.

I'm a little off the mark, but close enough to make some small adjustments in the engine components/compression and chassis/body weight to get a bit closer.

I know that it's just gonna be a simple driveway built shitbox, but as almost sits now, weight to power where it is, it'll be close to the ratio of some pretty respectable new factory rides:

Audi TT

This is what you're really thinking, isn't it, TC?

http://www.youtube.com/watch?v=xanvi_3o4YQ

yeah, but he wants to do that on the way to the ice cream place in downtown Kingston...

Ed-check this old Topolino out...last 20 seconds are a hoot:
http://www.youtube.com/watch?v=dQlL6WSuEmI

This engine is similar to what I designed for Merlot and built with a few changes by Pat Downs at CB Performance. The dyno test was at 145 HP!
(2058 CC)

If I got anywhere near 145hp (but I doubt it) that would put the Fiat close to the Chevy Corvette C6 at 8 to 1. That would be hysterical . . . but insane.

At 10.8 to 1, the Dodge Challenger almost seems approachable.

In a home-made Fiat of all things.

My 2 cents about the over-square engines...Cam selection is critical. Merlot's engine was designed based upon my dirt track racing experience. This type of engine is for acceleration out of turns (curves on the road) She rapidly twists the tachometer to the right. Not convinced you need 10/1 compression ratio.

I think the ratios he listed are pounds to horsepower, not static compression.

Without knowing the CC of the combustion chamber and the piston selection
(to compute CR ) , i'd sooner try to guess the number of hurricanes this season .

So , anywhere between 100 and 350 .

With the barrel shims and deck height, the CR looks be just about 8.3:1 . . . higher than I might like it, but it's a bit of a toy so I can deal with it for now.

But even a rough estimate of 100 hp is good enough to figure things out.

I think that the car is going to be plenty fast enough to not embarrass me on the highways. I have a drag car, and two track cars, and an everyday car. I want this to be a fun car, and it seems like it'll be all that and more.

Horsepower coming up where it is, all of the work gone into the suspension and brakes, weight so low, it'll be a tiny terror for sure and fit between rolling traffic lanes with ease.

Perfect !

Thanks,

TC