Stock head gasket limits. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Inabj2 · 06-07-2012, 05:56 AM

Was a consensus ever reached on how much power a stock head gasket and bolts will take before the head lifts? Doing research around the years I see numbers posted from as low as 320 whp to no higher then 350 maybe 400 rwhp. But I suspect that this estimates were made with pump or lower grade race gas, where pre detonation is most likely the factor rather then boost alone. Assuming that pre detonation is not an issue as I use E85 what do you think the maximum power a stock long block sr20det can achieve before the head lifts? What is the most power anyone has reached using a completely unopened long block? (camshafts and oil pan allowed as these are easy bolt ons.)

jr_ss · 06-07-2012, 07:07 AM

You'll lift the head thus rendering your stock headgasket garbage. Plenty of people have taken the stock gasket w/ upgraded hardware into the deep 400s. If the motor is open, atleast throw a new OEM gasket and ARPs in and you should be good to go for awhile.

Inabj2 · 06-07-2012, 07:24 AM

Motor is closed and running 20.6 psi of boost on E85, on a road tune, that was done for a previous built motor. This motor was supposed to be a temporary motor, however this has been my temporary motor for over 2 years.

I went to a dyno day recently and it turned out my car made 455 almost 456 rwhp and almost 350 lb-ft. Seeing how I been at this power level for some time, And how fuel richens up a bit after 7,000 rpm I think there is room for more power if fuel leans just a bit up top, and perhaps find if timing is ideal or if it can be advanced even more.

I wonder has anyone done 500 rwhp or over in stock headgasket and bolts? I know for sure of one car with over 450 in my personal experience this has turned out to be reliable. But I can't help but feel that I may be pushing my luck, if I go further.

*fliprayzin240sx* · 06-07-2012, 03:09 PM

I've seen people in Japan run fresh stock HG on ARP studs push to over 500 whp. From what I've been told by a particular builder, head will start lifting after 600hp. To keep the head from lifting, you run bigger head studs.

Inabj2 · 06-07-2012, 10:48 PM

Well that is not very comforting, I am running a 15 year old head gasket and studs, and I want to retune it. I don't want to turn the boost up, but I want to advance timing some more (running only 25-27 degrees so far.) And lean it up to 12:1 ratio. And ok maybe 1 psi more couldn't hurt.

As it stands right now.

jr_ss · 06-08-2012, 04:50 AM

Quote:

Originally Posted by Inabj2

Well that is not very comforting, I am running a 15 year old head gasket and studs, and I want to retune it.

What were you expecting? It's a relatively cheap upgrade and less chance of you lifting the head. If it were me, I'd do the preventative gasket studs, then get it retuned.

Inabj2 · 06-08-2012, 12:36 PM

Bah, what is the unopened long block power record anyways? My friend that does the tuning is telling me just fix it if the headgasket pops.

S@nt0s · 06-08-2012, 01:35 PM

your roughly where i would keep it. ive seen complete stock motors on C16 make 460 and with E85 running cooler it will help but your around the range where its a flip of the coin. I lifted my head with a T76@28psi wit ARp's but now on a 6266@33psi and zero lift. it seen 35-40psi spikes too and all checked out. i wouldnt go any leaner and timing same thing. im on forged pistons and i have more timing but i wouldnt push the stockers any more then that

06-07-2012, 05:56 AM	#1
Inabj2 Join Date: Feb 2007 Location: Glendale Arizona Age: 41 Posts: 14 Trader Rating: (0) Feedback Score: 0 reviews	Stock head gasket limits. Was a consensus ever reached on how much power a stock head gasket and bolts will take before the head lifts? Doing research around the years I see numbers posted from as low as 320 whp to no higher then 350 maybe 400 rwhp. But I suspect that this estimates were made with pump or lower grade race gas, where pre detonation is most likely the factor rather then boost alone. Assuming that pre detonation is not an issue as I use E85 what do you think the maximum power a stock long block sr20det can achieve before the head lifts? What is the most power anyone has reached using a completely unopened long block? (camshafts and oil pan allowed as these are easy bolt ons.)

06-07-2012, 07:07 AM	#2
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,415 Trader Rating: (35) Feedback Score: 35 reviews	You'll lift the head thus rendering your stock headgasket garbage. Plenty of people have taken the stock gasket w/ upgraded hardware into the deep 400s. If the motor is open, atleast throw a new OEM gasket and ARPs in and you should be good to go for awhile. __________________ My SR20VET Does your VTC gear rattle in your S14/15 SR? PM me.

06-07-2012, 03:09 PM	#4
fliprayzin240sx Man w/ CTSV & a Car Seat Join Date: Aug 2002 Location: Tampa Posts: 17,998 Trader Rating: (19) Rides Gallery: fliprayzin240sx Feedback Score: 19 reviews	I've seen people in Japan run fresh stock HG on ARP studs push to over 500 whp. From what I've been told by a particular builder, head will start lifting after 600hp. To keep the head from lifting, you run bigger head studs. __________________ If you think Zilvia has too many assholes... CLICK HERE!!!

06-08-2012, 01:35 PM	#8
S@nt0s Zilvia Addict Join Date: Jan 2008 Location: 310 all day! Age: 44 Posts: 912 Trader Rating: (4) Feedback Score: 4 reviews	your roughly where i would keep it. ive seen complete stock motors on C16 make 460 and with E85 running cooler it will help but your around the range where its a flip of the coin. I lifted my head with a T76@28psi wit ARp's but now on a 6266@33psi and zero lift. it seen 35-40psi spikes too and all checked out. i wouldnt go any leaner and timing same thing. im on forged pistons and i have more timing but i wouldnt push the stockers any more then that __________________ MunkyW3rkz Racing

06-07-2012, 07:24 AM	#3
Inabj2 Join Date: Feb 2007 Location: Glendale Arizona Age: 41 Posts: 14 Trader Rating: (0) Feedback Score: 0 reviews	Motor is closed and running 20.6 psi of boost on E85, on a road tune, that was done for a previous built motor. This motor was supposed to be a temporary motor, however this has been my temporary motor for over 2 years. I went to a dyno day recently and it turned out my car made 455 almost 456 rwhp and almost 350 lb-ft. Seeing how I been at this power level for some time, And how fuel richens up a bit after 7,000 rpm I think there is room for more power if fuel leans just a bit up top, and perhaps find if timing is ideal or if it can be advanced even more. I wonder has anyone done 500 rwhp or over in stock headgasket and bolts? I know for sure of one car with over 450 in my personal experience this has turned out to be reliable. But I can't help but feel that I may be pushing my luck, if I go further.

06-07-2012, 10:48 PM	#5
Inabj2 Join Date: Feb 2007 Location: Glendale Arizona Age: 41 Posts: 14 Trader Rating: (0) Feedback Score: 0 reviews	Well that is not very comforting, I am running a 15 year old head gasket and studs, and I want to retune it. I don't want to turn the boost up, but I want to advance timing some more (running only 25-27 degrees so far.) And lean it up to 12:1 ratio. And ok maybe 1 psi more couldn't hurt. As it stands right now.

06-08-2012, 12:36 PM	#7
Inabj2 Join Date: Feb 2007 Location: Glendale Arizona Age: 41 Posts: 14 Trader Rating: (0) Feedback Score: 0 reviews	Bah, what is the unopened long block power record anyways? My friend that does the tuning is telling me just fix it if the headgasket pops.