passing smog sc300 gte head gasket/ arp head bolts
11-11-15, 10:00 PM
#1
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Thread Starter
passing smog sc300 gte head gasket/ arp head bolts
Question for those whom may know I was wondering if a 1993 sc300 would pass smog in California with oem gte head gasket with arp head bolts everything else will be left stock I am going to have head off so I figure its best to do it now if I ever plan on going na-t.
11-12-15, 02:17 AM
#2
Hey Travi,
I hate to say it but this sounds very doubtful. I understand where you're coming from but no, this most likely will not pass smog in CA. While going to an OEM GTE head gasket and ARP bolts (with OEM/Toyota GTE washers btw) is a good step for an NA-T build, you will be throwing off your factory compression ratio so significantly you're going to affect combustion for the dyno test which will probably raise some of your measured exhaust gasses beyond the limits allowed in the dyno & sniffer test.
Also, another side effect of lowering the compression ratio without boost is that you will kill your stock horsepower and torque and make the car respond very sluggishly.
Further, you're aware that an NA-T setup will never pass smog visual in CA? Possibly the tailpipe dyno test as well... not that it matters one way or the other at that point.
I am not trying to be harsh-- that is not my aim at all. It's just an unfortunate set of realities here.
I hate to say it but this sounds very doubtful. I understand where you're coming from but no, this most likely will not pass smog in CA. While going to an OEM GTE head gasket and ARP bolts (with OEM/Toyota GTE washers btw) is a good step for an NA-T build, you will be throwing off your factory compression ratio so significantly you're going to affect combustion for the dyno test which will probably raise some of your measured exhaust gasses beyond the limits allowed in the dyno & sniffer test.
Also, another side effect of lowering the compression ratio without boost is that you will kill your stock horsepower and torque and make the car respond very sluggishly.
Further, you're aware that an NA-T setup will never pass smog visual in CA? Possibly the tailpipe dyno test as well... not that it matters one way or the other at that point.
I am not trying to be harsh-- that is not my aim at all. It's just an unfortunate set of realities here.
11-12-15, 09:25 AM
#3
It depends on how tight the numbers are over there, do you have the last emissions test to see how close you were before? if you had lots of room then you should be fine, usually stock cars that work properly come in way under the limits but if you are on the edge then that might do it.
if you have a little room then I think you would be fine since its just lowering the compression a little its not drastically lowering it just going from 10 to 9.2ish, not 8.5 like the gte has. the sc300 in stock form doesn't have trouble passing generally speaking and I don't think just the headgasket is going to throw off the balance that much. I have had passing numbers with a gte headgasket and a non working egr with all kinds of ecu's etc... but that was not cali, so unless the numbers in CA are that much stricter than everywhere else you could be fine. you can always add a bit of E85 to the tank and it will run smoother and cleaner for a while.
think about an sc300 that has a bit of a worn engine, it would effectively have lower compression, but it could still pass if all the systems are working. there is a bit of an allowance built in to the limits but not enough to let you slap on turbo's etc..
if you have a little room then I think you would be fine since its just lowering the compression a little its not drastically lowering it just going from 10 to 9.2ish, not 8.5 like the gte has. the sc300 in stock form doesn't have trouble passing generally speaking and I don't think just the headgasket is going to throw off the balance that much. I have had passing numbers with a gte headgasket and a non working egr with all kinds of ecu's etc... but that was not cali, so unless the numbers in CA are that much stricter than everywhere else you could be fine. you can always add a bit of E85 to the tank and it will run smoother and cleaner for a while.
think about an sc300 that has a bit of a worn engine, it would effectively have lower compression, but it could still pass if all the systems are working. there is a bit of an allowance built in to the limits but not enough to let you slap on turbo's etc..
11-12-15, 12:10 PM
#4
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Thread Starter
Yes that was my thought I came close to passing with my 5 speed with the same set up but it still came out to high nox , I wanted to go gte hg mostly for the matter of the heads being machined to make up for how much was machined
11-12-15, 12:46 PM
#5
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I talked to a friend here in Cali he said his has passed. If not might see to running a little e85 the motor is pretty much getting a rebuild so egr and stuff will be cleaned, new valve stem seals, oem gte hg, arp head studs, new air,oil,fuel filter, ngk iridiums and ngk wires, new gaskets all around.
11-12-15, 01:17 PM
#6
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Thread Starter
It depends on how tight the numbers are over there, do you have the last emissions test to see how close you were before? if you had lots of room then you should be fine, usually stock cars that work properly come in way under the limits but if you are on the edge then that might do it.
if you have a little room then I think you would be fine since its just lowering the compression a little its not drastically lowering it just going from 10 to 9.2ish, not 8.5 like the gte has. the sc300 in stock form doesn't have trouble passing generally speaking and I don't think just the headgasket is going to throw off the balance that much. I have had passing numbers with a gte headgasket and a non working egr with all kinds of ecu's etc... but that was not cali, so unless the numbers in CA are that much stricter than everywhere else you could be fine. you can always add a bit of E85 to the tank and it will run smoother and cleaner for a while.
think about an sc300 that has a bit of a worn engine, it would effectively have lower compression, but it could still pass if all the systems are working. there is a bit of an allowance built in to the limits but not enough to let you slap on turbo's etc..
if you have a little room then I think you would be fine since its just lowering the compression a little its not drastically lowering it just going from 10 to 9.2ish, not 8.5 like the gte has. the sc300 in stock form doesn't have trouble passing generally speaking and I don't think just the headgasket is going to throw off the balance that much. I have had passing numbers with a gte headgasket and a non working egr with all kinds of ecu's etc... but that was not cali, so unless the numbers in CA are that much stricter than everywhere else you could be fine. you can always add a bit of E85 to the tank and it will run smoother and cleaner for a while.
think about an sc300 that has a bit of a worn engine, it would effectively have lower compression, but it could still pass if all the systems are working. there is a bit of an allowance built in to the limits but not enough to let you slap on turbo's etc..
11-12-15, 01:24 PM
#7
do you know how much was the head machined? if the head was machined then the gte headgasket will affect it less and you should probably use a gte headgasket at that point anyways to keep a reasonable squish in the head, again it matters how much was taken off and if the head has been decked before.
if its the first deck and only .010" was taken off, then you could get away with the stock gasket and run good gas always with a compression ratio just above 10:1, guessing I would say around 10.2:1, if you run a gte gasket then more around 9.5:1.
if it was decked before or decked .020" or more then you are getting into the territory where you should always use a gte gasket on the motor, and if you are going na-t do note it wont drop your compression as much as before, you may only get to 9.6-9.7:1 compression or so. It may be a good idea to do GTE pistons also or source another GE cylinder head.
Do keep in mind that a cylinder head that needs a .020" decking (usually from an overheat or BHG) or more total means that the head is not true anymore. as in they can deck the bottom flat, but the top where the cams ride in are still warped. while there is some play and tolerance for that, there is a decent chance the cam's will not like that and can lead to a cam or top end failure eventually. something to keep in mind that the cylinder head at this point is close to being toast and if it works it will not like another decking at all, and should have probably been tossed in favor of another used cylinder head.
some people don't realize that the whole cylinder head warps, not just the bottom. so if you have any funny top end noises after assembly, that could be why.
also e85 will lower nox, but might raise HC's a little bit. do some reading online.
I would say if you are going to try it and the head needed decking, throw it together with a gte headgasket, its safer in the longrun.
without knowing the history of the cylinder head using a GE gasket can raise the compression enough to not like regular gas after a decking, and it has more of a chance of being an inteference motor at a certain point. using the gte gasket corrects all those issues but the cam journals being possibly out of line.
you shouldn't have been so high on nox, maybe double check the timing isn't advanced that can cause that as well. you can go 10 +/- 2 degrees and be in spec, lowering it helps with nox, raising the timing increases nox.
if its the first deck and only .010" was taken off, then you could get away with the stock gasket and run good gas always with a compression ratio just above 10:1, guessing I would say around 10.2:1, if you run a gte gasket then more around 9.5:1.
if it was decked before or decked .020" or more then you are getting into the territory where you should always use a gte gasket on the motor, and if you are going na-t do note it wont drop your compression as much as before, you may only get to 9.6-9.7:1 compression or so. It may be a good idea to do GTE pistons also or source another GE cylinder head.
Do keep in mind that a cylinder head that needs a .020" decking (usually from an overheat or BHG) or more total means that the head is not true anymore. as in they can deck the bottom flat, but the top where the cams ride in are still warped. while there is some play and tolerance for that, there is a decent chance the cam's will not like that and can lead to a cam or top end failure eventually. something to keep in mind that the cylinder head at this point is close to being toast and if it works it will not like another decking at all, and should have probably been tossed in favor of another used cylinder head.
some people don't realize that the whole cylinder head warps, not just the bottom. so if you have any funny top end noises after assembly, that could be why.
also e85 will lower nox, but might raise HC's a little bit. do some reading online.
I would say if you are going to try it and the head needed decking, throw it together with a gte headgasket, its safer in the longrun.
without knowing the history of the cylinder head using a GE gasket can raise the compression enough to not like regular gas after a decking, and it has more of a chance of being an inteference motor at a certain point. using the gte gasket corrects all those issues but the cam journals being possibly out of line.
you shouldn't have been so high on nox, maybe double check the timing isn't advanced that can cause that as well. you can go 10 +/- 2 degrees and be in spec, lowering it helps with nox, raising the timing increases nox.
Last edited by Ali SC3; 11-12-15 at 01:32 PM.
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11-12-15, 03:15 PM
#8
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Thread Starter
[QUOTE=Ali SC3;9250960]do you know how much was the head machined? if the head was machined then the gte headgasket will affect it less and you should probably use a gte headgasket at that point anyways to keep a reasonable squish in the head, again it matters how much was taken off and if the head has been decked before.
if its the first deck and only .010" was taken off, then you could get away with the stock gasket and run good gas always with a compression ratio just above 10:1, guessing I would say around 10.2:1, if you run a gte gasket then more around 9.5:1.
if it was decked before or decked .020" or more then you are getting into the territory where you should always use a gte gasket on the motor, and if you are going na-t do note it wont drop your compression as much as before, you may only get to 9.6-9.7:1 compression or so. It may be a good idea to do GTE pistons also or source another GE cylinder head.
Do keep in mind that a cylinder head that needs a .020" decking (usually from an overheat or BHG) or more total means that the head is not true anymore. as in they can deck the bottom flat, but the top where the cams ride in are still warped. while there is some play and tolerance for that, there is a decent chance the cam's will not like that and can lead to a cam or top end failure eventually. something to keep in mind that the cylinder head at this point is close to being toast and if it works it will not like another decking at all, and should have probably been tossed in favor of another used cylinder head.
some people don't realize that the whole cylinder head warps, not just the bottom. so if you have any funny top end noises after assembly, that could be why.
also e85 will lower nox, but might raise HC's a little bit. do some reading online.
I would say if you are going to try it and the head needed decking, throw it together with a gte headgasket, its safer in the longrun.
without knowing the history of the cylinder head using a GE gasket can raise the compression enough to not like regular gas after a decking, and it has more of a chance of being an inteference motor at a certain point. using the gte gasket corrects all those issues but the cam journals being possibly out of line.
you shouldn't have been so high on nox, maybe double check the timing isn't advanced that can cause that as well. you can go 10 +/- 2 degrees and be in spec, lowering it helps with nox, raising the timing
Thankyou man this is very helpful and I am not re using the same head, friend had 2 spare ones and head was not shaved before it will be the first time being decked mostly to have a very flat surface to work with also might swap out block. I am getting plenty of help from a close friend that is na-t but its a drift car no need to worry about smog
if its the first deck and only .010" was taken off, then you could get away with the stock gasket and run good gas always with a compression ratio just above 10:1, guessing I would say around 10.2:1, if you run a gte gasket then more around 9.5:1.
if it was decked before or decked .020" or more then you are getting into the territory where you should always use a gte gasket on the motor, and if you are going na-t do note it wont drop your compression as much as before, you may only get to 9.6-9.7:1 compression or so. It may be a good idea to do GTE pistons also or source another GE cylinder head.
Do keep in mind that a cylinder head that needs a .020" decking (usually from an overheat or BHG) or more total means that the head is not true anymore. as in they can deck the bottom flat, but the top where the cams ride in are still warped. while there is some play and tolerance for that, there is a decent chance the cam's will not like that and can lead to a cam or top end failure eventually. something to keep in mind that the cylinder head at this point is close to being toast and if it works it will not like another decking at all, and should have probably been tossed in favor of another used cylinder head.
some people don't realize that the whole cylinder head warps, not just the bottom. so if you have any funny top end noises after assembly, that could be why.
also e85 will lower nox, but might raise HC's a little bit. do some reading online.
I would say if you are going to try it and the head needed decking, throw it together with a gte headgasket, its safer in the longrun.
without knowing the history of the cylinder head using a GE gasket can raise the compression enough to not like regular gas after a decking, and it has more of a chance of being an inteference motor at a certain point. using the gte gasket corrects all those issues but the cam journals being possibly out of line.
you shouldn't have been so high on nox, maybe double check the timing isn't advanced that can cause that as well. you can go 10 +/- 2 degrees and be in spec, lowering it helps with nox, raising the timing
Thankyou man this is very helpful and I am not re using the same head, friend had 2 spare ones and head was not shaved before it will be the first time being decked mostly to have a very flat surface to work with also might swap out block. I am getting plenty of help from a close friend that is na-t but its a drift car no need to worry about smog
11-15-15, 12:13 AM
#9
Hey Travis,
Your options:
1) Hook up $$$; or
2) Try to rebuild your GE to pass smog and buy / build another GE for NA-T - this involves a lot of work but we live in CA so pay to play...
IF YOU FAIL SMOG the first time, option #1 will not be avaliable anymore.
Your options:
1) Hook up $$$; or
2) Try to rebuild your GE to pass smog and buy / build another GE for NA-T - this involves a lot of work but we live in CA so pay to play...
IF YOU FAIL SMOG the first time, option #1 will not be avaliable anymore.
11-15-15, 03:43 PM
#10
Very true about option #1 not being available if you fail and get directed to a Test Only station... or the BAR if you get flagged under some other random circumstance. There are also those roadside smog checkpoints that occasionally pop up. I've only seen one in my area once but that was enough evidence for me.
Travi19, the only predictable fully risk-free way to pass smog with a turbo SC in CA is with a USDM GTE swap. Lot of work.
There are some cars around that somehow aren't configured that way but I can't begin to tell you how they do it and keep their vehicles like that more than two years at a time.
Last edited by KahnBB6; 11-15-15 at 09:16 PM. Reason: Grammatical corrections
11-16-15, 08:05 AM
#11
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Thread Starter
Yea very true. I know car would not pass with turbo put in but I myself was wondering if the car would pass with lowered compression with everything else stock. Getting mixed answers but I feel anyone that is not changing the compression greatly and cleans up all smog equipment while heads are off and set timing to as ali suggested I feel there are many ways to get the car to smog as I had one with the same set up and passed everything exept for the nox, and I did nothing other then clean the egr and it dropped nox considerably but still didn't pass.
11-16-15, 08:17 AM
#12
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Thread Starter
I loathe that phrase "pay to play" but you're right, ross. In CA it's an undeniable truth when it comes to reliable horsepower in any small, sporty RWD car.
Very true about option #1 not being available if you fail and get directed to a Test Only station... or the BAR if you get flagged under some other random circumstance. There are also those roadside smog checkpoints that occasionally pop up. I've only seen one in my area once but that was enough evidence for me.
Travi19, the only predictable fully risk-free way to pass smog with a turbo SC in CA is with a USDM GTE swap. Lot of work.
There are some cars around that somehow aren't configured that way but I can't begin to tell you how they do it and keep their vehicles like that more than two years at a time.
Very true about option #1 not being available if you fail and get directed to a Test Only station... or the BAR if you get flagged under some other random circumstance. There are also those roadside smog checkpoints that occasionally pop up. I've only seen one in my area once but that was enough evidence for me.
Travi19, the only predictable fully risk-free way to pass smog with a turbo SC in CA is with a USDM GTE swap. Lot of work.
There are some cars around that somehow aren't configured that way but I can't begin to tell you how they do it and keep their vehicles like that more than two years at a time.
I did end up having the 'hookup' for my last sc300 at a test only station I might look into trying to find a place willing to test the car without putting it in the books so if it does fail it won't be in the computer. I still have not put the hg on but honestly the friend of mine helping me work on the car strongly suggests the 1.3 hg after head has been machined. Car may pass smog first time but I bet over time carbon build up will make it fail after a few months of driving around. The friend helping me is the one that has done it to one of his cars and got it to pass
11-16-15, 08:52 AM
#13
carbon buildup brings the compression back up. you dont have much of a choice if you deck the head more than .01 then run a gte gasket and worry about the rest later. If you want to keep it 100% stock, then you need a replacement cylinder head, you can even get one from a gs300. there are lots available.
11-16-15, 09:42 AM
#14
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Thread Starter
carbon buildup brings the compression back up. you dont have much of a choice if you deck the head more than .01 then run a gte gasket and worry about the rest later. If you want to keep it 100% stock, then you need a replacement cylinder head, you can even get one from a gs300. there are lots available.
11-16-15, 10:03 AM
#15
not much really that would be worth it, only headgasket, pistons, or head work will change compression.
I would just put it back together with the gte headgasket and see where you are at.
Nox means high cylinder combustion temps, which you can also help by lowering the timing 1 or 2 degrees... HC will go up but if you have a little room on that number then it can work out. you have to be +/- 2 degrees from 10 degrees though so you have a 4 degree range to work with before techs complain. also there is the e85 as mentioned.
I would just put it back together with the gte headgasket and see where you are at.
Nox means high cylinder combustion temps, which you can also help by lowering the timing 1 or 2 degrees... HC will go up but if you have a little room on that number then it can work out. you have to be +/- 2 degrees from 10 degrees though so you have a 4 degree range to work with before techs complain. also there is the e85 as mentioned.