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Author
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Topic: Long rod 302
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SundanceKid
Gearhead Posts: 1137
From: UT
Registered: Feb 2001
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posted 03-05-2003 03:37 PM
   
Anyone done one of these? As I understand it, the longer the rod the better the rod ratio the less flow you will need in the heads due to the piston dwell at TDC..yada yada...but in the real world. Is a long rod 302 based engine worth the effort? Just looking for some opinions?
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Mpcoluv
Gearhead Posts: 1144
From: Charlotte NC usa
Registered: Apr 2001
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posted 03-05-2003 04:06 PM
A guy wrote several "Long Rod" articles in Hot Rod years ago. The chevy article was an outright lie. As of several months ago, the "Long Rod" motor was never fired up, much less perform as the article stated.
Long rods mean a lot (under 10 hp) to guys trying to squeeze the last bit of HP out of a motor limited by rules.
For a street/strip motor, it is not worth the money. You won't see much gains.
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jdsgallops
Gearhead Posts: 326
From: Naples, FL
Registered: Feb 2001
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posted 03-06-2003 12:18 AM
Hang on there, from my research not everything that Mpcoluv said is true. I don't know anything about the chevy engine, but there has been much written about a long rod engine. The 302 is already a long rod engine, with a 1.71 ratio(if I remember correctly). Long rods work best in an engine with limited breathing ability. An engine that breathes well won't see much if any benefit from going to a longer rod. A lond rod engine is also more detonation sensitive because the piston dwells at top dead center longer. This extended dwell time is also part of the advantage though as it pushes the air out longer. The detonation thing wouldn't really be an issue unless running a power adder IMO. Regardless of benefits and draw backs, think about it this way. To build a long rod engine you need new rods and a custom set of pistons. why spend $500 on rods and $5-700 on pistons, when you can buy a complete stroker kit for a small block ford now days for the same price. The longer stroker will give you more power in a more usable power range than any long rod will. Best rule of thumb I have heard on this subject is "use the longest rod available for your intended application. This goes back to stroke, deck height, and desired piston compression height(ie, power adder or N/A). With the price of a stroker kit nowdays, any arguement about rod ratio is really pointless.
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stoker
Gearhead Posts: 155
From: folsom,cal,
Registered: Jan 2002
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posted 03-06-2003 08:55 PM
sundancekid,i have a long rod 302 rotater kit with lots of extras for 450.00.if interested email me [email protected]
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Moneymaker
Administrator Posts: 21725
From: Lyons, IL, USA
Registered: May 99
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posted 03-06-2003 09:18 PM
The only time I ever saw anything with a longer rod SBF was when used with a stroker crank.
I tried some 5.250 stuff years ago with a two ring piston on a bracket 302 and it ran about the same as a similar 302. The cylinder walls did not wear any less.
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Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00,'01,'02,&'03
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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steve'66
Gearhead Posts: 7226
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 03-06-2003 10:03 PM
From David Reher's article in Nat'l Dragster, Talking to racers and customers, I've realized that drag racing lost almost an entire generation during the '70s and '80s. Many
younger racers didn't climb the same learning curve that people of my generation did. I understand why: When I was a teenager, my friends and I couldn't wait to put a new cam in a '67 Camaro or bolt a set of gears into a SS396 Chevelle. But the effects of several Energy Crises and emission regulations meant that cars became simply transportation appliances when the next generation was growing up. They were more interested in computers and camcorders than camshafts and carburetors. Now that some of the members of this "lost generation" are rekindling an interest in racing, they need the basic information that my generation learned taking apart street cars in our driveways. We also wanted to point out some of the common myths and misconceptions about high-performance motors. For example, I've seen dozens of magazine articles on supposedly "magic" connecting rod ratios. If you believe these stories, you would think that the ratio of the connecting rod length to the crankshaft stroke is vitally important to performance. Well, in my view, the most important thing about a connecting rod is whether or not the bolts are torqued! If I had to make a list of the ten most important specifications in a racing engine, connecting rod length would rank about fiftieth. Back in the days when Buddy Morrison and I built dozens of small-block Modified motors, we earnestly believed that an engine needed a 1.9:1 rod/stroke ratio. Today every Pro Stock team uses blocks with super-short deck heights, and we couldn't care less about the rod ratio. A short deck height improves the alignment between the intake manifold runners and the cylinder head intake ports, and helps to stabilize the valvetrain. These are much more important considerations than the rod-to-stroke ratio. There's no magic - a rod's function is to connect the piston to the crankshaft. Period.
******************************************* That's good enough for me. 
SteveW
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SundanceKid
Gearhead Posts: 1137
From: UT
Registered: Feb 2001
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posted 03-06-2003 11:40 PM
I didn't specify real, but I ment more towards the street and head flow side of things not full out racing and wear on the bores.
I myself agree that there is no benifit to be had, or if there is it is minor. Does anyone have any opinions on head flow?
Alex would it be legal to run a long rod engine in classes that the heads can't be ported for the nessesary flow needed ect.
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