Question for those who built their iorn block

devilish64

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I am putting together the parts to do my first modular build in my 07 gt500. I am intending to have a local machine shop who does a lot of modular stuff do all the machine work i need on my original 20k mile iorn block. My question is to those who have built their iorn block, what bore size were you able to achieve with the block? My research tells me .030 over on a 5.4 iorn block is pretty much the max bore without sleeves. I would like to do as little boring or honing as possible to try and keep as much strength as possible. I know every block will be slightly different..... but what did you guys wind up getting away with on your blocks. Thanks in advance, chad
 

merkyworks

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^+1

Keep the bore wall as thick as possible. If you can get away with maybe a 0.005" re-hone/overbore I would do that and get pistons to match. 0.030" is typically considered the max you can safely overbore a traditional iron block.
 

HKusp

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I have a question and it may seem dumb, but bear with me. Why are you boring a block with only 20K miles on it?
 

devilish64

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i would like to start with a set of known to be perfectly round holes. So weather i need a slight hone or a bore i dont really know until i take the block to the machine shop. I intend this motor to hold 1000+rwhp
 

devilish64

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My car made 870rwhp on the stock motor almost a few years ago now.... so it is on borrowed time. Id like to not ruin my block, crank and cylinder heads. That is a main motivating factor to building the motor. Plus i love working on this car and I have just about "bolted" everything i can to it. Probably time for a bigger blower
 

FEARSNO1

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if you want to push hard on the motor, hone it as little as possible. on my last built motor, i cracked a cylinder sleeve around 1300hp. so that is a weak point that you will be making weaker. that block was stock bore also.
 

devilish64

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if you want to push hard on the motor, hone it as little as possible. on my last built motor, i cracked a cylinder sleeve around 1300hp. so that is a weak point that you will be making weaker. that block was stock bore also.
So are you saying you cracked the factory iorn block @ ~1300 crank hp? Or was it a aftermarket sleeve in the iorn block that cracked? Thanks for the information..... it sounds like it was an expensive way to learn the limits of the factory stuff. I dont know why i wanna do something similar.... but i do.
 

FEARSNO1

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It was a factory iron block, stock sleeves just upgraded rotating assembly. It was making close to 1300rwhp when it let go, it pushed coolant out the degas tank and then I also had water in the oil when I got back home. I was running 31-32 psi of boost on the KB 4.0, with some nitrous on top of it.

I still won the race though.....it was a guy that was talking a bunch of trash too so it was worth it! Lol, that motor was about 8 years old and 25k miles at over 1000hp so it didn’t owe me anything!
 

devilish64

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WOW..... now that was the info i was looking for..... thats a TON of power
It was a factory iron block, stock sleeves just upgraded rotating assembly. It was making close to 1300rwhp when it let go, it pushed coolant out the degas tank and then I also had water in the oil when I got back home. I was running 31-32 psi of boost on the KB 4.0, with some nitrous on top of it.

I still won the race though.....it was a guy that was talking a bunch of trash too so it was worth it! Lol, that motor was about 8 years old and 25k miles at over 1000hp so it didn’t owe me anything!
 

devilish64

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It was a factory iron block, stock sleeves just upgraded rotating assembly. It was making close to 1300rwhp when it let go, it pushed coolant out the degas tank and then I also had water in the oil when I got back home. I was running 31-32 psi of boost on the KB 4.0, with some nitrous on top of it.

I still won the race though.....it was a guy that was talking a bunch of trash too so it was worth it! Lol, that motor was about 8 years old and 25k miles at over 1000hp so it didn’t owe me anything!
how did you solve this problem out of curiosity? I assume its...... make less power lol
 

FEARSNO1

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No other solution but to have it sleeved, but I didn’t want to spend that kinda cash, after reviewing the logs, my alternator wasn’t putting out enough voltage and actually made the car run lean as the fuel injectors were at 130% duty cycle and AFR was in the mid to high 12’s. So I’m hoping that was a main contributor, and definitely didn’t help for sure. So I’m hoping a fresh block and a new alternator keeps it together.
 

fullboogie

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Would love to know how your datalogging showed your injector DC to be at 130%. Would you mind putting up some logs?
 

FEARSNO1

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Would love to know how your datalogging showed your injector DC to be at 130%. Would you mind putting up some logs?


Here ya go, this was when it actually let go, injector duty cycle was actually at 146%, voltage at 11.94, boost at 31 and LC-1 is AFR at 13.6! This was with 3-465’s and ID1300’s. The voltage issue just compounded the problem as I was already on the edge of the 1300’s to start with. As the voltage dropped the ECU tried to compensate by increasing injector duty cycle.
 

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fullboogie

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Thanks man - didn't know it was possible to log >100% on the DC. Good info.

By the way, fellow Lafayette guy here.
 

devilish64

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So i decided i would really like to keep this motor im building standard bore to keep as much strength in the block as possible. I am in the process of trying to locate a new 5.4 iron block wich is proving to be a little difficult. I wanted to try and put a motor together while leaving the motor running in my gt500 as to keep the downtime to a minimum. My research tells me 5.4 iron engines like in our cars use the 5.4 nvh block also found in a few other ford vehicles. Can i expect to find a lower mileage(under 100k mile) engine that was running to steal the block and expect it to be able to get away with just a hone and keep it standard bore?? Or is this not gonna happen more than likely? My gt500 is less than 20k miles but i would like to keep the factory shortblock intact if possible. I know the only one that can truely answer this is the machine shop.... but i dont want to waste the time and money on getting a new to me used block for it to not fit my goals for the build. Thanks for any help.... this is the first(and last lol) modular build i want to do for this car so i really want to get it right.
 

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