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Old 01-29-2016, 02:10 PM   #1
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Default How far can i push it on standard head bolts

As above. Ive tried every combination of search term going - Best i found was in the DIY FAQ, which only says 'somewhere above 250hp'

I want to run somewhere between 250-275hp, and if i can get away with just rods then i will. I aint made of money.

Car is to be used on track.

Thanks.
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Old 01-29-2016, 02:19 PM   #2
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Honestly that's probably going to be fine. Most people don't know where the upper limit is because going above 250whp safely requires opening the engine and spending 100 bucks on head studs when you put the head back is basically free. I was running 18 psi for over a decade, most of that time was on stock head bolts.

edit: I see you're just going to upgrade rods. I personally feel that you're pushing your luck going for 275whp on a track car with just rods. If your tune has any problems, you might have a bad time. If you lose a piston, a rod could go through a cylinder wall and you're going to be a few grand in the hole just to get the car running again.
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Old 01-29-2016, 03:52 PM   #3
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the rods are the weak link; they bend above ~250rwtq. you can just as easily kill forged pistons with bad tuning.
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Old 01-29-2016, 03:54 PM   #4
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275hp is like 250whp
You'd prob be ok with a stock engine at this point
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Old 01-29-2016, 05:24 PM   #5
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Rods will bend as low as 225 ft/lbs when driven hard on the track.

You tell us, i'm interested how long they hold up.
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Old 01-29-2016, 07:02 PM   #6
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Im fitting forged conrods. My question is about the head bolts. Wheres the limit?

Ta always broken. Im pretty confident about my abilities to tune, and have heard that stock pistons are good up to 300 without knock. Headgasket good to above 450 thnks to the head lifting thread. Only variable left is the head bolts atm
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Old 01-29-2016, 07:07 PM   #7
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You tell us. I'm interested in how long they hold up.
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Old 01-29-2016, 07:11 PM   #8
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If you torque them correctly, they'll be fine. I ran mine around 350whp and it lifted the head, but I later discovered my torque wrench put them at 40 or 42 ft*lbs. I have head studs now, but wouldn't be afraid to run stock bolts to 400whp if you have a torque wrench that is verified to work correctly.
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Old 01-29-2016, 07:25 PM   #9
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Perfect, thanks. Waayy above what im going to be running then.

I did find, on my travels, a few posts hinting that the main bearing cap fasteners need changing at ~300hp. Not sure this is worth the worry though.

Otherwise, i dont think ive got any other parts to buy. Thank god. This '1 grand build' has cost almost triple that so far...

Last edited by sparkybean; 01-30-2016 at 07:59 AM.
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Old 01-30-2016, 05:44 PM   #10
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Quote:
Originally Posted by sparkybean View Post
Perfect, thanks. Waayy above what im going to be running then.

I did find, on my travels, a few posts hinting that the main bearing cap fasteners need changing at ~300hp. Not sure this is worth the worry though.

Otherwise, i dont think ive got any other parts to buy. Thank god. This '1 grand build' has cost almost triple that so far...
I had a budget of $1500. I think I'm $6k in..
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Old 01-30-2016, 07:57 PM   #11
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I budgeted 2500. I'm at like 8 or 9 k. See a common theme here?
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Old 01-30-2016, 08:10 PM   #12
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I am actually within budget on the current build. Looks like I'll be in the 3000-3500 range including new pistons, refreshed head, new oil pump, harmonic balancer and clutch. I can't even imagine how much it would have been if I paid someone else to do it for me.

Extremely cheap engine builds don't make any sense to me, since there is a lot of small stuff that isn't part of your "list" of mods you are officially doing and it really eats into your budget. Timing belt, head gasket, bearings, etc all add up. On a 3k engine build, 500 bucks of nickel and diming doesn't really hurt that much. On a 1k engine build, it's half your budget. And then in another year or two, you're going to punch yourself because you had the engine open and you didn't take care of everything.
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