Set me straight on pump gas
05-14-2013, 09:32 PM
#21
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Wow buick, you guys have some awesome pump gas what can i say. 19 degrees on pump making over 700hp, i don't know too many people running like that but i guess it works for you.
05-15-2013, 05:51 AM
#27
9 Second Club
If you lower the CR, then running pump gas is very viable.
When not racing I run mine with no water/meth and have no problems. Ive raced 1/4 miles this way too and around a race track.
Circa 9.0:1 and about 24-25psi at 7000rpm, although generally shift around 6700.
For most occasions given traction problems, there is little point using the meth, as it just reduces traction even further due to the power increase.
If I was doing pump fuel only and never any water/meth, I'd just lower the CR to maybe 8.5 or somewhere around that.
If you have E85 available there it would be a no brainer to use it. All I can get here is pump fuel, no E85 and race fuel is about 5-6x the price of the already mega expensive pump fuel.
When not racing I run mine with no water/meth and have no problems. Ive raced 1/4 miles this way too and around a race track.
Circa 9.0:1 and about 24-25psi at 7000rpm, although generally shift around 6700.
For most occasions given traction problems, there is little point using the meth, as it just reduces traction even further due to the power increase.
If I was doing pump fuel only and never any water/meth, I'd just lower the CR to maybe 8.5 or somewhere around that.
If you have E85 available there it would be a no brainer to use it. All I can get here is pump fuel, no E85 and race fuel is about 5-6x the price of the already mega expensive pump fuel.
05-15-2013, 07:42 AM
#28
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how long does a tank of water meth last? i know nothing about meth injection . im trying to see what i can get out of e-85 or 93 octane for my show car. im looking to build a 410-427 ci lsx block. callies magnum and olivers rods, je pistons. not sure on heads or cam. twin 68s or 72s.
05-15-2013, 08:10 AM
#31
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If you lower the CR, then running pump gas is very viable.
When not racing I run mine with no water/meth and have no problems. Ive raced 1/4 miles this way too and around a race track.
Circa 9.0:1 and about 24-25psi at 7000rpm, although generally shift around 6700.
For most occasions given traction problems, there is little point using the meth, as it just reduces traction even further due to the power increase.
If I was doing pump fuel only and never any water/meth, I'd just lower the CR to maybe 8.5 or somewhere around that.
If you have E85 available there it would be a no brainer to use it. All I can get here is pump fuel, no E85 and race fuel is about 5-6x the price of the already mega expensive pump fuel.
When not racing I run mine with no water/meth and have no problems. Ive raced 1/4 miles this way too and around a race track.
Circa 9.0:1 and about 24-25psi at 7000rpm, although generally shift around 6700.
For most occasions given traction problems, there is little point using the meth, as it just reduces traction even further due to the power increase.
If I was doing pump fuel only and never any water/meth, I'd just lower the CR to maybe 8.5 or somewhere around that.
If you have E85 available there it would be a no brainer to use it. All I can get here is pump fuel, no E85 and race fuel is about 5-6x the price of the already mega expensive pump fuel.
05-15-2013, 08:24 AM
#32
The limits of pump gas have more to do with dynamic compresson than horsepower.
On an average setup (between 8:1 and 10:1 compression), 93 pump gas will start to have issues around 18 PSI of boost. With lower piston compression you might get away with a little bit more.
Example: My 05 Neon SRT4 on a stock turbo was around 300 whp and started to have issues with 93 pump hitting 19 PSI. Slight detonation. Upgraded to a bigger turbo and was knocking on 400 whp at the same 19 PSI before I started getting detonation again.
Then you increase the displacement up to an LS motor. You can make 600whp all day on a stock compression LS at 16 or so PSI, but you're at the limit for pump gas on that setup. Swap to twins, you'll make more power at the same PSI, and still be able to use pump gas.
Swap to a larger LS like a 427, and make 800+ at 16 PSI on a single with pump gas or even 1000+ with twins and pump gas.
Go with 500+ cubic inches and a pair of large turbos, you can probably shoot for as high as 1500 on pump gas. Vipers do this all of the time with ~500 cubic inches and large twins. There are quite a few of them running around 1250+ on 93 pump. Nelson sells 632 inch TT Big blocks rated for 1500 HP on pump gas.
Things can be done to raise the threshold, like a proper intercooler setup, removing intake restrictions, using a good cooling system, an most of all, A GOOD TUNE. 20+ PSI can be done on pump gas on a well designed and tuned setup.
Meth injection will raise the threshold. Water injection will raise it even further.
E85 still qualifies as pump gas and has a higher knock resistance than what most people will ever need in a street car when properly tuned.
Keep the dynamic compression down
On an average setup (between 8:1 and 10:1 compression), 93 pump gas will start to have issues around 18 PSI of boost. With lower piston compression you might get away with a little bit more.
Example: My 05 Neon SRT4 on a stock turbo was around 300 whp and started to have issues with 93 pump hitting 19 PSI. Slight detonation. Upgraded to a bigger turbo and was knocking on 400 whp at the same 19 PSI before I started getting detonation again.
Then you increase the displacement up to an LS motor. You can make 600whp all day on a stock compression LS at 16 or so PSI, but you're at the limit for pump gas on that setup. Swap to twins, you'll make more power at the same PSI, and still be able to use pump gas.
Swap to a larger LS like a 427, and make 800+ at 16 PSI on a single with pump gas or even 1000+ with twins and pump gas.
Go with 500+ cubic inches and a pair of large turbos, you can probably shoot for as high as 1500 on pump gas. Vipers do this all of the time with ~500 cubic inches and large twins. There are quite a few of them running around 1250+ on 93 pump. Nelson sells 632 inch TT Big blocks rated for 1500 HP on pump gas.
Things can be done to raise the threshold, like a proper intercooler setup, removing intake restrictions, using a good cooling system, an most of all, A GOOD TUNE. 20+ PSI can be done on pump gas on a well designed and tuned setup.
Meth injection will raise the threshold. Water injection will raise it even further.
E85 still qualifies as pump gas and has a higher knock resistance than what most people will ever need in a street car when properly tuned.
Keep the dynamic compression down
Last edited by HexenLord; 05-15-2013 at 08:46 AM.
05-15-2013, 09:32 AM
#33
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There's been plenty of people make some power on pump gas. different people have different opinions on what is high hp. The most I have made with pump gas is 743 to the wheels With a single turbo on a lt1. I have a c5 corvette with twin 62's that makes 670 rwhp and I haven't turned a wrench on it in 2 years.
05-15-2013, 10:30 AM
#35
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how long does a tank of water meth last? i know nothing about meth injection . im trying to see what i can get out of e-85 or 93 octane for my show car. im looking to build a 410-427 ci lsx block. callies magnum and olivers rods, je pistons. not sure on heads or cam. twin 68s or 72s.
As for the claim that pump gas can only handle 18-19psi, it is complete nonsense. First off as I use more than that on my LS. And as for other platforms, over the last 20 years Ive tuned loads of 4cyl cars running up to 30psi boost with zero issues on straight 93 pump gas. That's some with factory CR and some even slightly higher ranging up to around 600hp from a 2.0
Anything over 30psi and I generally would add water/meth or methanol to the fuel, and have run up to around 38psi boost with pump + water/meth on Subaru engines ( properly built of course )
And it is all about compression ratio. Too high and you'll be forever knock limited and have to run such low timing it would be detrimental in every respect. Lower the CR and you will still be able to run a good amount of timing for that setup and it will be safe as long as EGT's are kept in check.
05-15-2013, 11:37 AM
#37
9 Second Club
My tank is about 6-7 litres. I inject a lot of fluid, but still that's really only about 5-6 minutes worth.
I can empty the tank in a days racing ( 1/4, some 1km runs and a short circuit ). If it was 1/4 only, then a tank would last a full day no problem
So how long it lasts depends on pump, nozzles, tank size and when it is set to come on.
Obviously the less you inject the longer it will last, and of course bigger tank.
05-15-2013, 12:06 PM
#38
05-15-2013, 01:27 PM
#39
But how long is that in actual real time usage in seconds ?
My tank is about 6-7 litres. I inject a lot of fluid, but still that's really only about 5-6 minutes worth.
I can empty the tank in a days racing ( 1/4, some 1km runs and a short circuit ). If it was 1/4 only, then a tank would last a full day no problem
So how long it lasts depends on pump, nozzles, tank size and when it is set to come on.
Obviously the less you inject the longer it will last, and of course bigger tank.
My tank is about 6-7 litres. I inject a lot of fluid, but still that's really only about 5-6 minutes worth.
I can empty the tank in a days racing ( 1/4, some 1km runs and a short circuit ). If it was 1/4 only, then a tank would last a full day no problem
So how long it lasts depends on pump, nozzles, tank size and when it is set to come on.
Obviously the less you inject the longer it will last, and of course bigger tank.
