Safe PSI w/ Pumpgas and sub 9:1 static compression
02-21-2008, 11:29 AM
#1
Safe PSI w/ Pumpgas and sub 9:1 static compression What are you bigger guys running? I'm looking at having around 8.3:1 in a 366 with an S480. I'd like to be able to play in the Pump gas drags next year and was wondering how far you can safely get away with on pump. Also if I should shoot for a higher CR as well to get away with it.
Would 18-20 psi be out of the question if I snuck up on it? DD would probably be limited to around 12-14 psi...just turn up the wick at the track. The exhaust is very free flowing (5") and is a 1.32a/r T6 flanged 80mm with the race cover.
Thanks,
Marty
Would 18-20 psi be out of the question if I snuck up on it? DD would probably be limited to around 12-14 psi...just turn up the wick at the track. The exhaust is very free flowing (5") and is a 1.32a/r T6 flanged 80mm with the race cover.
Thanks,
Marty
02-21-2008, 05:57 PM
#2
I've had quite a few 25-27psi highway pulls on pump gas with my 101mm 346. I didn't have any problems and the plugs looked good, but i don't plan on it happening very often. If i had to guess it was around 1200rwhp.
02-21-2008, 06:16 PM
#3
My experience is that any 8.5/1 motor can run very reliably at 15 psi boost. Going up to 18 is possible, but makes things pretty unforgiving. I've heard of 20 - 22, but a bad tank of gas, some heat soak, or a change in ambient conditions can smoke a motor.
Mike
Mike
02-21-2008, 09:52 PM
#5
Jesus man, tell me you have meth and are running ridiculously low timing, that is crazy. I really wanted to do a thumper setup but supposedly the 80mm ETT wheel with the race cover flows almost 140lb/min. I think that should get me to my goals with a 366. Maybe 850rwhp through a TH400 would suffice just fine at 3100 lb raceweight.
02-22-2008, 08:23 AM
#7
LS1Tech Co-Founder
iTrader: (34)
I have an 8:1 348ci LS6 and a T6 88mm turbo. My 867rwhp thru TH400 was with race gas, like 112 I think, Speed Inc tuned it. That was 25psi I think, Jim would know. I think I could run 15psi which would in my case double my probably 350rwhp to 700rwhp. I'm guessing I would run some easy 9.50's, I'm not sure but maybe it could go 9.3's.
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02-22-2008, 09:50 AM
#8
370, 8.5 CR with 80gts and plan to boost 15-18 psi on pump gas. I got a meth kit if I need it and will set it up to spray on the high side for insurance. Also got an A2W intercooler and gonna integrade a rad with a fan in the system. Will be too mcuh hastle and lazy for ice at the track. I know this is how Mightymouse has his setup and it works great for him even on the street. Plus I wanted to keep my bird in the bumper.
02-22-2008, 11:00 AM
#9
370, 8.5 CR with 80gts and plan to boost 15-18 psi on pump gas. I got a meth kit if I need it and will set it up to spray on the high side for insurance. Also got an A2W intercooler and gonna integrade a rad with a fan in the system. Will be too mcuh hastle and lazy for ice at the track. I know this is how Mightymouse has his setup and it works great for him even on the street. Plus I wanted to keep my bird in the bumper.
02-23-2008, 01:00 PM
#12
I've got 8.8:1 with 15#'s on 93 octane with meth injection and a lot of timing (26 degrees) and it is daily driven with no problems. Honestly I could probably run 20-22#'s no problem on the same setup as my tune was way safe and had a lot of room for extra boost.
Honestly if your goal is 18-20#'s on pump gas, I would say as long as everything is forged how it should be you could get away safely with either 8.5:1 on just pump gas, or 8.8:1 with meth injection. Honestly with the meth injection, you might even be able to do 9:1 still with pump gas and be safe as a DD.
Honestly if your goal is 18-20#'s on pump gas, I would say as long as everything is forged how it should be you could get away safely with either 8.5:1 on just pump gas, or 8.8:1 with meth injection. Honestly with the meth injection, you might even be able to do 9:1 still with pump gas and be safe as a DD.
02-23-2008, 01:39 PM
#13
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02-23-2008, 01:51 PM
#14
With pump gas it really boils down to if you are leaving it as 'pump only' or if you are going to add meth. Like already mentioned, about 8.5 CR with pump only you should be able to run 15psi no prob and maybe a bit more. If you want higher cr about 8.8-9.0 than you'll most likely have to run a bit less boost and/or add some meth.
The question is, do you want to rely on meth? I for one don't want to at all. I will most likely have the boost set on 15 all of the time and depeding on how it works out I may spray a bit of meth ontop. My second setting will be whatever else I can get out of my setup, with meth of coarse, for when I take it to the track. I look at meth as being a bandaid myself and don't want to rely on it for the tune in case it fails. It will be more so that extra cooling aid and a bit of a bump with my **** 91 octane where I live in case of a **** tank of gas and/or on a hot *** day. Giving it that bit of extra 'safety measure' on high boost where failure seems to happen.
Everyone is different and I researched, researched and researched while talking to many about this to deside on which is 'best' for my needs. It really the question you have to ask yourself. Mines more of a street car and initially anyways, won't see much track to start. If it was more of a race car than I'd go with atleast bare minimum of 9.0 CR with less boost on the street with pump gas. While turning it up at the track with race gas. Wouldn't even screw around with the meth in that circumstance.
The question is, do you want to rely on meth? I for one don't want to at all. I will most likely have the boost set on 15 all of the time and depeding on how it works out I may spray a bit of meth ontop. My second setting will be whatever else I can get out of my setup, with meth of coarse, for when I take it to the track. I look at meth as being a bandaid myself and don't want to rely on it for the tune in case it fails. It will be more so that extra cooling aid and a bit of a bump with my **** 91 octane where I live in case of a **** tank of gas and/or on a hot *** day. Giving it that bit of extra 'safety measure' on high boost where failure seems to happen.
Everyone is different and I researched, researched and researched while talking to many about this to deside on which is 'best' for my needs. It really the question you have to ask yourself. Mines more of a street car and initially anyways, won't see much track to start. If it was more of a race car than I'd go with atleast bare minimum of 9.0 CR with less boost on the street with pump gas. While turning it up at the track with race gas. Wouldn't even screw around with the meth in that circumstance.
02-23-2008, 01:58 PM
#15
With pump gas it really boils down to if you are leaving it as 'pump only' or if you are going to add meth. Like already mentioned, about 8.5 CR with pump only you should be able to run 15psi no prob and maybe a bit more. If you want higher cr about 8.8-9.0 than you'll most likely have to run a bit less boost and/or add some meth.
You can safely run 15#'s of boost on just pump gas with 9:1 CR. I was doing it with 8.8:1 and a ton of room left for a year. Then I wanted to add more timing so I went with the meth injection. I already could have ran a few more pounds of boost safely on just the pump gas, but now with the meth injection 20-22#'s would be easily attainable still on pump gas with the meth injection.
To say you want to stay away from meth injection just because you don't want to rely on it, or pay the 40 cents a gallon it will cost you for all the added benefits is foolish. I beat the snot out of my car last year and only went through 7 gallons of the water/meth mix, so its not like you'll be constantly filling the tank either. This guy is looking at running some big boost with the best CR, and to get that to its peak on pump gas, meth injection is really the way to go.
02-23-2008, 03:05 PM
#16
CALL911...I think the fact that you're supercharged also has a little to do with it. I don't think the turbo will be as tolerant. I'm going to probably shoot for a little over 8:1 and run what I can safely without meth for the time being. I'll add meth when the budget recovers from the first hit of mods...things are adding up quickly.
Marty
Marty
