Timing from 12,5* to 20*?

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p7100

Swedish
Joined
Mar 18, 2009
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How much diffrence does this make in horsepower and torque roughly?
Also intressted to know how driveability will change??
Thanks
 
I only gained about 19 HP going from 12.4 to 25* on my then nearly stock truck.

This number was calculated from 1/4 mile trap speed differences so it reflects average gain in horsepower throughout the RPM range, not gain in peak HP.

There was a little bit of a head wind when I made the higher timing passes so it might have been closer to 25 HP gain, but that's it. Nothing monumental or life changing.

I also noticed that the truck cranked over slower with the higher timing, almost like the injection event being early slows down the cranking speed of the truck and almost stalls the starter. It still starts fine, it just turns over slower.

On a higher HP truck, I could see timing add twice as much horsepower.
 
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like stated above... tends to idle louder, tneds to loose bottom end torque and open up top-end HP... pulls higher into the rpm band
 
now if it has a small charger it will not get that good of a gain because the exhaust is stopped up.
 
P7100,

You do know the increase in cylinder pressure when the timing goes up !:doh:
The head gasket will not take that abuse for too long before it goes south without a ticket.:evil
Studs are a minimum with fire rings after that.
You should stop at 16.5 till then.$.02
WAYNES WORLD
 
You guys are too conservative on your head studs, orings, and firering recommendations. A flat block, flat head, good gasket, and really tight head bolts will hold lots of cylinder pressure.

My 95' Junker runs 25* of timing, 75psi boost, probably 100 psi exhaust drive pressure, and 2000+ EGT's. All on stock overtorqued head bolts at 150 ft lbs, and stock headgasket with 244K miles. Eventually it will probably let go but until then, I'm going to keep pushing it harder and harder till I find it's limit.

I'm confident I will see 650 HP and 1400 ft lbs to the wheels before I have head gasket issues.
 
Big Blue24 said:
You guys are too conservative on your head studs, orings, and firering recommendations. A flat block, flat head, good gasket, and really tight head bolts will hold lots of cylinder pressure.

My 95' Junker runs 25* of timing, 75psi boost, probably 100 psi exhaust drive pressure, and 2000+ EGT's. All on stock overtorqued head bolts at 150 ft lbs, and stock headgasket with 244K miles. Eventually it will probably let go but until then, I'm going to keep pushing it harder and harder till I find it's limit.

I'm confident I will see 650 HP and 1400 ft lbs to the wheels before I have head gasket issues.
Click to expand...


This comes up every time there is a timing thread or question.... I agree, 16.5* is for the whimps. My personal truck is running 24* on re torqued bolts to 130 ft lbs. My friend has 18* running on untouched bolts.

Experiment with your timing. Different trucks like different timing, mine was real fun at 21, the new motor build at 24 seems to be a nice spot.
 
alot has to do with boneheads not letting the motor come up to temp before bagging on it...
 
Kronic_187 said:
alot has to do with boneheads not letting the motor come up to temp before bagging on it...
Click to expand...

i also agree, i had 290k on a stock head gasket, never even had a retorque. 60 plus psi many times. but i also let it warm up to operating temps.
 
i popped my stock gasket... but i had "butter bolts" after i tried retorqueing stockers... so i knew it was gonna go eventually... luckily i had enough "borrowed" time to locate an IH head to get decked, new valves and a good 3 angle job done to... then a set of A1 studs and a .010+ thicker Cummins gasket... no troubles now an hits 50+ psi daily.

i think a NEW set of stocker headbolts when torqued down tightly should do fairly well, not completely sold on the necessity of 0-rings yet... i think way too many guys forget to realize that there stocker headbolts have upwards of 200,000 miles of heat cycles on them when they go to retorque.... i learned the hard way... buy a set of new bolts, then torquing them to 130 ft/lbs or so would probably have done the trick for me.

BUT, lesson learned.
 
As far as stock head bolts I touqed mine to 145 and I had about 75 psi before the n20 and had no head gasket issues. That was at about 19*.
 
Are you guys torquing immediately from stock position, or are you taking them out, lubing them and then torquing up?
 
This turned out to a really good thread. Just keep the info comming and personal experience flowing=).
 
The best way is to get new head bolts and torque it down good n tight aka german specs
 
I took mine out and put a little oil on the threads. Stock 200k bolts on new motor and 250k bolts on the old motor

Big Blue24 on here just torqued them from where they were. didnt take them out
 
I bumped my timing from 18* to 26* when I had an hx35 on it. Then installed 12mm arp's one at a time using plenty of their moly lube WITHOUT removing the head. Now I have twins, ddp4's, full cuts and 328k miles. 70psi and holding just fine.

I think a lot of it depends on how your truck has been taken care of, and how you drive it. A well maintained truck that has been warmed up before every drive, not floored when it's cold....... I could go on and on.
 
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