I want to go longer rods so I can pull more hp out of the same engine. I asked about 6" rods a week or so ago and then saw that I can get 6.250" rods. Is that trying to get too much leverage? Am I going to run into clearance problems somewhere? I can get Wiseco pistons to match with -3cc dish. Or should I just stick with 6" rods.

 

Longer rods will give you a very small increase in performance. It will stay together longer at sustained rpms though. If you go too long, the pin in the piston becomes really high in the pistion--somtimes into the rings. If it was me, I would spend the money used on longer rods on something that will give you a much bigger performance boost. In a street engine, the longer rods aren't of much use. In a circle track car, sure.


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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, currant red metallic paint. Lots of other stuff...
82camaro

 

Since I am wanting to stay TBI on my new engine, I am trying to free up as much horsepower out of the motor as I can. I can get the rods for pretty much the same cost as the 6" but the pistons will cost more. I am sure with 6.25" rods the pin will be in the oil ring. Is that going to cause oil burning problems once the engine gets some mileage on it? I know by using the long rods I can yield more horsepower out of the same air/fuel intake charge but am I going to sacrifice longevity of the engine. Is there anyone else using a 6.25" rod on here? Are there any happy 6" rod users that have 60k miles + on their engine.

 

If it's your daily driver then don't use pistons that have the wrist pin going into the bottom oil ring. No, it won't cause oil burning (they've got it worked out a little better than that!) but it's not as durable a setup.

 

Not to be a twit, but with a TBI motor, both of those extra horsepower that you might get with longer rods are going to be the 2 most expensive ones you've ever bought...

That's the kind of thing you do if you're running in some situation that has real tight rules and lots of cars that all run the same like Super Stock or Winston Cup does, and there's thousands of dollars on the line, and you need an extra half a hundredth to beat the other guy with an otherwise totally identical car. You'd get probably 2 or 3 times as much improvement in ET by each one of a very long list of simple, cheap things like changing your rear end grease to synthetic, or dyno-tuning your timing and mixture, or installing a restriction-free cold-air induction instead of a "drop-base" open element, or losing a couple of pounds by putting in an aluminum water pump, or installing a set of rear LCA lowering brackets; and without every one of that sort of thing already done, you'll never even notice the minute difference that the trick rods (and their $1000 price tag by the time they're installed) is going to make.

"Pick the low hanging fruit" first before you go for the real expensive, esoteric, theoretical tweaks like non-standard rod lengths.

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"So many Mustangs, so little time..."
ICON Motorsports

 

$1000 for a set of rods is a bit much. The rods I am looking at is http://cgi.ebay.com/ebaymotors/aw-cg...item=598228209

Which for h-beam rods isn't any more expensive than 5.7 rods. But if it is not going to be as durable as 5.7 rods then I won't go that route.

 

Machine work, special (probably custom!) pistons, racing-only rings, file-fitting, balancing, etc.... that stuff adds up in a big hurry. There's always additional costs beyond just the stuff that comes in the boxes when you do things like that. What you're talking about doing is not a matter of opening the box and slapping it together, like 1.6 rocker arms or something; it's one-off custom all the way.

Rods alone are only the tip of the iceberg. Pistons are going to be $50 apiece or more, compared to $15 for hypereutectic or $25 for TRWs; and so on. I'd be surprised actually if you could make that one seemingly simple change (6.25" rods for 5.7" rods) for $1000, even if you could do all the labor yourself except balancing the crank.

My point is not so much that you shouldn't do it or that it's inherently bad somehow, although if it's a street driven motor, it will cause the rings to be short-lived. Rather, the main issue is that what you're proposing has an extremely high "buck to bang" ratio. If you evaluate your mods on a $$$ per HP basis, you'll find that it doesn't look too good compared to a whole bunch of other possibilities. For example, you're looking at costs in the same ballpark with buying a set of heads! Yet, heads will give you 20 or 30 or maybe even more HP for your $1000, while those rods might give you 2. Might. Hmmm.... I'm going to spend $1000 on some horsepower.... for my hard-earned cash I have a choice, I could either get 30 HP, or I could get as much as 2 HP maybe.... let me call my financial adviser for his wisdom on this one....

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"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited November 20, 2001).]

 

I prefer good blunt honesty. Everyones more bang for their buck. I have considered just buying a L98 shortblock from scoggin dickey for $1050 and run some AFR 190cc heads with a LT4 hot cam and my 454 TBI. Maybe I should go milder like vortec heads and LT1 cam. For the bang to buck ratio.

 

The big gain with longer rods is that a lighter piston will have to be used. A

Gotta agree with the rest, put that money into something else, aftermarket heads, TPI intake, etc....