[7178Chevyman]

I am looking to build a nice 383 for strip use only, but am still on a budget, first off I have read other posts and do not find answers I'm looking for. I would like to know if the 6" rod is better for my strip application, and I'm also looking to run an 11 to 1 Cr with a 64cc head. Will I be able to run this on a mix of 93 and 110 octane, or should I be better off with 10:7.1 cr due to fuel detonation issues, since I'm on a budget I don't need any catastrophic failure. The pistons either way will be forged. Thank you for all your help any info or opinions are appreciated.

 

[bigdog7373]

You will every one of thise answers if you search. This gets discussed here at least twice a week because nobody uses the search feature.
5.7 rods are more common.
11:1 will require fuel with higher than 93 octane. I wouldnt go more than 10.5:1 max.
Go full forged if you think you will want forced i duction, if not then a cast crank steel will be fine but i'd still use forged rods just to be safe.

 

[CNC BLOCKS NE]

I have always used 6 inch rods

Better rod ratio

Less piston sticking out of the bottom of the bore at TDC with 6 inch rods

Pistons are liter

Balancing with a crank for a 6 inch rods will be internally where some 5.7 rod cranks have to be balanced exteranally.

From what I have seen 6 inch rods in a 383 seems more popular.

 

[farmwalker]

I think 6 inch rods give you a better rod ratio. But 5.7 are more comon. And I don't think you will have to go forged unless you do nos of forced induction, and that will help your budget alot. And you will have to balence the rotating assembaly no matter what if you want any kind of performance. You don't want to build a shaker. Also you maybe able to get away with the highest octane street gas if you go with alluminum heads cause you can go a little higher in compression but not much. But that is pushing it. I had a friend who did it and it worked... But Im sure he's the exception not the rule.

 

[vinniekq2]

(I am looking to build a nice 383 for strip use only,) if its strip use then use strip gas

 

[68NovaSS]

(I am looking to build a nice 383 for strip use only,) if its strip use then use strip gas

Agreed.

The only thing I don't like about 6 inch rods is the oil ring runs through the pin boss on 383 stroke pistons for 6" rods, I've heard of oil control issues, but never experienced it, I use 5.7 rods in my blower motors. Any gains from rod ratio between the two rod lengths is miniscule, you'll find two schools of thought on that one. JMO

 

[CNC BLOCKS NE]

Agreed.

The only thing I don't like about 6 inch rods is the oil ring runs through the pin boss on 383 stroke pistons for 6" rods, I've heard of oil control issues, but never experienced it, I use 5.7 rods in my blower motors. Any gains from rod ratio between the two rod lengths is miniscule, you'll find two schools of thought on that one. JMO

You should really post factual info instead of hear say, If there was an oil control issue the piston companies would build them.

I have build many eninges with oil rail supports and so for no oil control issues!!!!

I use alot of Mahle pistons and there pistons use no oil control rings for 6 inch rods.

Rod ratio is key when building a good performance engine.

Also with the 6 inch rods there is less side loading and less friction over a 5.7 rod.

 

[lmsport]

Go with wither high or low compression. Trying to crutch the engine to use some gas concoction is just a hassle. For race only, I would got to 12.5:1 and just run straight 110. Each point of compression is about 10% more peak horsepower and an increase in torque at every RPM.

 

[ap72]

You should really post factual info instead of hear say, If there was an oil control issue the piston companies would build them.

I have build many eninges with oil rail supports and so for no oil control issues!!!!

I use alot of Mahle pistons and there pistons use no oil control rings for 6 inch rods.

Rod ratio is key when building a good performance engine.

Also with the 6 inch rods there is less side loading and less friction over a 5.7 rod.

6" rods seem to work well all around on 383's, no argument there.

But piston companies are like any other company, they sell a product to make money, not warm fuzzy feelings. Someone will sell you whatever your heart desires for the right price, pistons included.

 

[ap72]

Go with wither high or low compression. Trying to crutch the engine to use some gas concoction is just a hassle. For race only, I would got to 12.5:1 and just run straight 110. Each point of compression is about 10% more peak horsepower and an increase in torque at every RPM.

10%! Wow, that number seems to get bigger every day. Just last week it was about 2-3%.

 

[vinniekq2]

re imsport,,Each point of compression is about 10% more peak horsepower and an increase in torque at every RPM.
I bet that new Mazda engine that has 14:1 CR is a rocket then????

 

[7178Chevyman]

So basically from what I understand is use a 6 inch rod and use110 octane with an 11.1 CR. Thank you all and keep the info and opinions coming!

 

[vinniekq2]

whats your budget and goals?

 

[7178Chevyman]

I would like to stay under3 grand for sure , I would like to think I could get around 450 horses with this budget and still have a reliable but hot motor

 

[vinniekq2]

what parts do you currently own? IE crank/block/heads?

 

[7178Chevyman]

I have block and heads but I still maybe buying heads . I am looking at cast scat crank forged rods and flat tops. That said that said is about 900 bucks

 

[vinniekq2]

what heads do you own?have they been flow tested?what block?
machine work and balancing of a race engine can go as high as $800.oo,,,$250 oo for gaskets and timing chain. that leaves 2k for rotating parts,,, buy a used intake,,good carbs are $600.oo,,,fill in the blanks from here, Good camshaft and kit 375?

 

[ap72]

You can get 450hp out of a 350 on 87 octane... so why bother with a 383 and 110 octane? Seems like a lot of wasted money and effort.

 

[7178Chevyman]

I have a set of original double humps, old technology so like I said probably be buying heads also

 

[vinniekq2]

double hump what? 194s or 202s? screw in studs or pressed? list all your parts please