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-   -   ANY one ever build one of the long rod engines..... (http://www.hotrodders.com/forum/any-one-ever-build-one-long-rod-engines-167754.html)

6sally6 11-02-2009 05:41 PM

ANY one ever build one of the long rod engines.....
 
Many of the magazines have article on?
I have read about many combinations but NEVER heard from anyone who actually built one!!
I am interested in the one that uses a 400SBC engine block with a 3.25" stroke(327 crankshaft) and uses the 6.123" FORD 300six cylinder rods. (Heck uva combo ,huh?!) Its SUPPOSE to produce huge torque figures on lo- octane gas. Make over 400 HP.
My pal and I are interested in building such engine for a circle-track(dirt) racer. The cu. in. limit is 350 cubes. THIS would give us the size but with a HUGE piston and short stroke.
Got lotsa questions for ANYONE who has first hand knowledge of this engine build.
Thanx
6sally6

S10 Racer 11-02-2009 06:03 PM

Quote:

Originally Posted by 6sally6
Many of the magazines have article on?
I have read about many combinations but NEVER heard from anyone who actually built one!!
I am interested in the one that uses a 400SBC engine block with a 3.25" stroke(327 crankshaft) and uses the 6.123" FORD 300six cylinder rods. (Heck uva combo ,huh?!) Its SUPPOSE to produce huge torque figures on lo- octane gas. Make over 400 HP.
My pal and I are interested in building such engine for a circle-track(dirt) racer. The cu. in. limit is 350 cubes. THIS would give us the size but with a HUGE piston and short stroke.
Got lotsa questions for ANYONE who has first hand knowledge of this engine build.
Thanx
6sally6

You are destroking a 400. There is some controversy over whether stroking a motor is really worth the cost so I would imagine the same would hold true for destroking one as well. I wish I could give you some useful info. I would think that destroking the 400 would be a screamin motor (high rpm's) but as far as more torque and over 400 hp, that's questionable. JMHO

techinspector1 11-02-2009 06:13 PM

http://www.purplesagetradingpost.com...%20engine.html

6sally6 11-02-2009 06:17 PM

Well the article..........
 
was at purplesage.com. It was all about using the looong FoMoCo rods to build the torque while maintaining the 350 cu. in. Sort of a "the engine GM should have built."
My question is.....will these long rod engines re-act favorably with long duration camshafts?! ALL the article use these short no. duration cams. I know short numbers make more torque........but will the long duration cams work well with the long rod theory in a race application?!

techinspector1 11-02-2009 06:54 PM

Quote:

Originally Posted by 6sally6
was at purplesage.com. It was all about using the looong FoMoCo rods to build the torque while maintaining the 350 cu. in. Sort of a "the engine GM should have built.

HUH? Did you click on the link I posted?

6sally6 11-02-2009 07:14 PM

That was the article that started this whole thang.........
 
I read it years ago and then again the other night! You too,huh?! Did you read my last post about cam choice for long rod engines in a RACE application?
You know.....I just thought....Winston Cup/Sprint Cup/ whatever...they do the long rod and big cam stuff don't they?!
6sally6

k-star 11-02-2009 07:18 PM

rods
 
Read this,

http://www.iskycams.com/techtips.php

Go to the tech 2005 about connecting rods. When your done open the 2 files and compair the piston locations between the rods.

I am getting some popcorn... This question comes up on every car site 2 or 3 times a year and it always gets interesting.


I got $500 to anyone that can prove to me they made more power with a longer rod. I have been offering this for the last 3 or 4 years and i still have my money...


Keith

CNC BLOCKS NE 11-03-2009 05:28 AM

We build a lot of 2 barrel circle track engines and going from a 5.7 to a 6.250 on a SBC we see both make peak power at about the same RPM about 6800 but the long rod engine at 750o PRM will make average 30 more horse over the short rod engine.

In turn we can run more gear and turn the engine more.

Most tests are done with the same cam but the engines breath different between the 2 and do require a different cam.

Tom at http://www.3vperformance.com/ use to be my old business partner years ago and he has worked for some of the top cup teams Roush, DEI and Toyota and his engines that run down south are top engines in their classes and those are all 6.250 rods in those engines.

On our SBC blower engines we run 6.300 rods in those engines 8 years in a row 1st and second.

Some of the classes we build for have a 5.7 rod lenth rule I wonder why.

oldbogie 11-03-2009 08:36 AM

Quote:

Originally Posted by 6sally6
Many of the magazines have article on?
I have read about many combinations but NEVER heard from anyone who actually built one!!
I am interested in the one that uses a 400SBC engine block with a 3.25" stroke(327 crankshaft) and uses the 6.123" FORD 300six cylinder rods. (Heck uva combo ,huh?!) Its SUPPOSE to produce huge torque figures on lo- octane gas. Make over 400 HP.
My pal and I are interested in building such engine for a circle-track(dirt) racer. The cu. in. limit is 350 cubes. THIS would give us the size but with a HUGE piston and short stroke.
Got lotsa questions for ANYONE who has first hand knowledge of this engine build.
Thanx
6sally6

This is one of those things that looks really good on paper, dyno's just enough to keep the argument alive with people thinking they saw something and continuing to chase it, basically if a little is good a lot is better kind of thing, but the result they're looking for is always just over the horizon. When you get it on the street or track, the time slips don't show anything and no you can't run it with a high state of tune at 11 to 1 compression on 87 octane unleaded moving a 4000 pound pick up with 3.08 gears. Reality is a far different place than dynamometers and computations.

Obviously there are limits on too short or too long out there on some extreme, but within reason, that being the Chevy 400 short rod and the 6 inch aftermarket rod, you'd be hard pressed to measure the difference in output or lifespan.

Bogie

SDLuck 11-03-2009 11:15 AM

Cup motors are large bore short stroke long rod,but also have large port 15 degree cylinder heads
http://www.roadsters.com/sbc/#R07

SDLuck 11-03-2009 11:18 AM

There is a guy running nhra with a rumor very shot rod and buzzes it really high.And is a class winner

Studebaker 11-06-2009 10:46 PM

Short rod.
 
You are right, Some of the nascar engines use long rods, but get real, they run 8000-9000 RPM and run one race. In a street engine the difference is so neglible you will never notice it. Longer rods weigh more, cause short piston ring stacks and higher wrist pin placement, this is not really that good for long term reliability in a street engine. Spend money elsewhere, like cylinder heads and valve train. it will be money well spent.

CNC BLOCKS NE 11-07-2009 06:17 AM

Quote:

Originally Posted by Studebaker
You are right, Some of the nascar engines use long rods, but get real, they run 8000-9000 RPM and run one race. In a street engine the difference is so neglible you will never notice it. Longer rods weigh more, cause short piston ring stacks and higher wrist pin placement, this is not really that good for long term reliability in a street engine. Spend money elsewhere, like cylinder heads and valve train. it will be money well spent.

Reread my post as we have seen from 5.7 to 6.250 a 30 horse gain at 7500 do your own reserch.

We have some engines street and strip with 1.000 compression height and no problems.

The engines you have run with the long rods what have been your problems or are you one that has never tried it and are posting just hear say.

SDLuck 11-07-2009 08:51 AM

There have been many articles written both ways on long and short rods.
Nascar guys say on restricter plate engines have better performance with long rods. There power band is different than a streetcar.Some companies switch back and forth between long and short rod in the same engines and dyno them. It was my understanding from Dema Elgin that the cams should be changed when the rods are changed and I have not seen that done in anything I have read.R & M did a article in National Dragster years ago and switching rods in a Big Block chevy did little or no difference

Studebaker 11-07-2009 01:35 PM

reply to CNC blocks
 
I currently have 2 SBC 400's one with standard stock 5.56 rods and the other with 6.0 rods. I haven't noticed any difference. These are street engines and don't turn over 6000 rpm.


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