head job
05-20-19, 06:06 PM
#1
Racer
Thread Starter
head job
I dropped an intake valve on cyl 6. Head needs to come off. The crazy thing is I have a set of BC264 cams and everything needed to do the swap (besides the head gasket) that I was close to swapping in. Pretty lucky this happened before the swap if it just had to happen or else I'd be doing a lot of the work again. I have a plan for a small NA-T build down the road and am debating speeding up that plan and using a thicker head gasket which should allow more psi safely. I calculate that a 2.5mm thick gasket will make 9:1 compression on a vvti engine. Unsure if this is a good plan for the time being while it's still N/A.
Anyone had experience with head gaskets on these cars and suggestions? Brands?
Anyone had experience with head gaskets on these cars and suggestions? Brands?
05-20-19, 10:19 PM
#2
Stock compression ratio is 10.5:1, with power at around 210 hp/torque. Going by the torque-gain formula of torque gain/loss = (newrc / oldrc ) * 0.4), that's sounds to be ((9.0 / 10.5) * 0.4), or... 0.34285, or... your 210 torque engine is now a 135 torque engine? Check my math, yet do you really want to drive around in a 135 ft/lb torque GS300, even for a short period of time...? How long until you get the NA-T build complete?
If you're really building a "small NA-T build", it appears best-practice is to use the stock/oem twin-turbo 1.3mm gasket, that will drop compression down to 9.6:1, give you up to 400rwhp capability, and decent low-rpm power. Supposedly, the 2.5mm hg gives you too little compression, making producing power a painfully slow process.
That's all if you're really doing a small build, and not going to change your mind later, wanting 600rwhp.
btw... no real-world experience with the 2jz-gte motor, plenty on the 3s-gte. Yet these motors have been around long enough, that the kinks have been worked out, if you're really going for a light-build.
If you're really building a "small NA-T build", it appears best-practice is to use the stock/oem twin-turbo 1.3mm gasket, that will drop compression down to 9.6:1, give you up to 400rwhp capability, and decent low-rpm power. Supposedly, the 2.5mm hg gives you too little compression, making producing power a painfully slow process.
That's all if you're really doing a small build, and not going to change your mind later, wanting 600rwhp.
btw... no real-world experience with the 2jz-gte motor, plenty on the 3s-gte. Yet these motors have been around long enough, that the kinks have been worked out, if you're really going for a light-build.
05-21-19, 06:04 AM
#3
Racer
Thread Starter
Thanks for the insight! Ya it seems 2.5mm is pretty extreme after researching more. I do think I'll do a set of ARP bolts while I'm in there so it will handle anything in the future. Not sure if I want to drop compression now. My original plan was a small NA-T build and the stock compression is fine for that. I have to remember, the car still needs to pass smog. So it probably needs the compression ratio to stay the same once the turbo kit is off and things back to normal looking.
As far as the tear-down and re-build, anything I need to watch out for or have prepared parts-wise? My tb/wp, and all ignition components are new. Head will be sent to the local machinist with my BC cams and properly clearanced while it gets the head job.
I found out that the service intervals calls for a valve clearance check every 60 thousand miles and adjust as necessary. I'm willing to bet this has never been checked on mine or most peoples for that matter. I think it is why the damage happened. The car was having an odd issue where it would randomly misfire when hot. But never showed signs or data for issues when testing. It was insufficient valve clearance that caused a loss of compression when hot and eventually wiped out the guide or whatever I'm going to find in there.
Some people on here have been dealing with a ghost misfire, if your symptoms are only when hot and mostly accelerating. Might consider checking valve clearance (cold it says) and if you find it tight, this will cause a misfire due to heat expansion. That's my story anyway.
As far as the tear-down and re-build, anything I need to watch out for or have prepared parts-wise? My tb/wp, and all ignition components are new. Head will be sent to the local machinist with my BC cams and properly clearanced while it gets the head job.
I found out that the service intervals calls for a valve clearance check every 60 thousand miles and adjust as necessary. I'm willing to bet this has never been checked on mine or most peoples for that matter. I think it is why the damage happened. The car was having an odd issue where it would randomly misfire when hot. But never showed signs or data for issues when testing. It was insufficient valve clearance that caused a loss of compression when hot and eventually wiped out the guide or whatever I'm going to find in there.
Some people on here have been dealing with a ghost misfire, if your symptoms are only when hot and mostly accelerating. Might consider checking valve clearance (cold it says) and if you find it tight, this will cause a misfire due to heat expansion. That's my story anyway.
05-21-19, 11:06 AM
#4
So now we've gone from "small NA-T build" to "handle anything in the future"...? 
I can't think of anything special, just proper tools, parts, and materials.
We've never done valve clearance, in 35yrs of Toyotas, all the way back to 4A-GEs. We have a 300k+ 5S-FE, which should have buckets/shims, and never even checked them. Maybe we'd see slight change in NVH or performance, yet... we're lazy?
Personally, if passing smog is your primary objective, I'd say stay with the oem hg, for a few reasons. 1) when you do the cams, if you change the hg, you'll have downgraded hp/torque from the cr drop, and you'll never know the a/b changes of just the cams. 2) it'll be a bit before you do the NA-T, so even without the cam change, if you were doing the hg, you won't enjoy the car's performance with the lower cr. 3) if smog is your primary objective, then when it comes time, swapping back the stock exhaust and de-powering everything else would be a lot easier... imagine adding in the time, after all that, of replacing the hg back, before putting it all back together... to again take it apart and put it back together. 4) if you really still are in the "small NA-T build" range, appears that the stock compression will be good for a bit of upgrade, as long as you don't go crazy... and maybe run rich, and maybe even water injection, to keep things cool.
It appears that with a stock hg and small NA-T build, you'd go from... 210hp to 260hp? Maybe even 300hp? When we upped our 3S-GTE from 160rwhp to 200rwhp (200-245hp?) via MBC and FIPK, the difference was ridiculously noticeable. If we had done exhaust/FCD, we should have seen 300hp, easily, with no other modes, and that's major changes in noticeable performance. I can't say what 40-50hp would be like in the weight of the GS300, yet unless you are in for the big-number, that might get you to GS4 territory (300hp/310torque?).
I can't think of anything special, just proper tools, parts, and materials.
We've never done valve clearance, in 35yrs of Toyotas, all the way back to 4A-GEs. We have a 300k+ 5S-FE, which should have buckets/shims, and never even checked them. Maybe we'd see slight change in NVH or performance, yet... we're lazy?
Personally, if passing smog is your primary objective, I'd say stay with the oem hg, for a few reasons. 1) when you do the cams, if you change the hg, you'll have downgraded hp/torque from the cr drop, and you'll never know the a/b changes of just the cams. 2) it'll be a bit before you do the NA-T, so even without the cam change, if you were doing the hg, you won't enjoy the car's performance with the lower cr. 3) if smog is your primary objective, then when it comes time, swapping back the stock exhaust and de-powering everything else would be a lot easier... imagine adding in the time, after all that, of replacing the hg back, before putting it all back together... to again take it apart and put it back together. 4) if you really still are in the "small NA-T build" range, appears that the stock compression will be good for a bit of upgrade, as long as you don't go crazy... and maybe run rich, and maybe even water injection, to keep things cool.
It appears that with a stock hg and small NA-T build, you'd go from... 210hp to 260hp? Maybe even 300hp? When we upped our 3S-GTE from 160rwhp to 200rwhp (200-245hp?) via MBC and FIPK, the difference was ridiculously noticeable. If we had done exhaust/FCD, we should have seen 300hp, easily, with no other modes, and that's major changes in noticeable performance. I can't say what 40-50hp would be like in the weight of the GS300, yet unless you are in for the big-number, that might get you to GS4 territory (300hp/310torque?).
05-21-19, 05:42 PM
#5
Racer
Thread Starter
By handle anything I just meant if I do a NA-T build or not. And I have decided I'm just going to stay with an OEM head gasket thickness. It's not worth the hassle when smog time comes. Looking forward to refreshing my head and seeing what the cam swap does. I do plan to have it dynoed eventually. Not sure when I'm going to have time for this yet.
05-22-19, 08:55 PM
#6
Racer
Thread Starter
Finally had a chance to research and price out/order my parts. Went with a Felpro oem spec MLS gasket best price through RockAuto, ARP head stud kit 203-4205 since I will be running cams and a future NA-T build. Cheapest on Amazon. And decided now is the time to replace the old stock oil pump. Aisin OPT-071. Also Cheapest through Amazon. Cam and crank seals kit from Dayco SK0040. Cheapest from Flea-bay. Already have valve cover intake and exhaust gaskets. And all timing components and my balancer are new.
Anything else anyone can think of I might be missing?
Anything else anyone can think of I might be missing?
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05-24-19, 05:26 AM
#8
Racer
Thread Starter
Just cheap insurance. The car is a 98, has high miles, and is going to ripped apart and rebuilt anyway. There are minor leaks here and there. None that ever make it to the ground. This job will cover every oil seal and gasket besides the oil pan. So I will tackle that someday too. Rear main isn't leaking. So it's just another way to get the car on point.
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