76mm/pump gas tuning help
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On The Tree
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From: SpringCity Tn
76mm/pump gas tuning help I don't post on here much. I read a lot. I need some advice on what to do next.
I run a local monthly event at my track and I need some more et out of my setup to be more competitive. Heads up racing 5.70 cap
basic setup: 5.3 punched .120 over. forged is piston h-beam rods etc arp everything. I just had a set of 862 heads ported polished bigger ss valves put in.
I'm running on3 76mm turbo. 20psi 93 pump gas and water/ice intercooler. 18 degree timing overall. 650 double pumper blow thru carb
I've currently ran 6.18@119mph pretty consistent. 1.42 60ft and car weighs 3200lbs.
my question is am I at the point I need to swap to race gas? I drive the car on the street a lot. so I was really wanting to stay pump gas. but I'm afraid of pushing it and not really gaining anything.
Also I'm running a dual plane intake. I'm fixing to swap to single plane next week.
at this point. what's the best bang for the buck? more boost + racegas?
I run a local monthly event at my track and I need some more et out of my setup to be more competitive. Heads up racing 5.70 cap
basic setup: 5.3 punched .120 over. forged is piston h-beam rods etc arp everything. I just had a set of 862 heads ported polished bigger ss valves put in.
I'm running on3 76mm turbo. 20psi 93 pump gas and water/ice intercooler. 18 degree timing overall. 650 double pumper blow thru carb
I've currently ran 6.18@119mph pretty consistent. 1.42 60ft and car weighs 3200lbs.
my question is am I at the point I need to swap to race gas? I drive the car on the street a lot. so I was really wanting to stay pump gas. but I'm afraid of pushing it and not really gaining anything.
Also I'm running a dual plane intake. I'm fixing to swap to single plane next week.
at this point. what's the best bang for the buck? more boost + racegas?
maybe up front but if you go straight to race gas that could get pricy by the end of the year
you wont have to go back and forth from race fuel to pump gas, just turn off the meth and lower timing back down for the street.
you wont have to go back and forth from race fuel to pump gas, just turn off the meth and lower timing back down for the street.
That is too much timing IMO for 20psi and pump gas. The A2W is probably helping a good bit though as is the blow through carb by keeping the fuel in contact with intake air longer than an efi set-up.
Have you put fresh plugs in it and pulled them at the end of the track or towed it back to know what's really going on?
That dual plane intake is also going to be really bad with fuel distribution and I'd bet that at that boost level you have one or more hot cylinders. Single plane will help tremendously.
I would look into methanol injection. Run 75 meth/25 water or even more methanol than that. I saw the same reduction in IAT's with 50% water as I did with 25% water at the boost level I was running. Although now that I think about it with your A2W intercooler your IAT's are going to be way lower than ambient anyways and that being said I would run 100% methanol for all the added octane you could possibly get.
You would be able to run the same amount of timing and more boost with the methanol injection which is what I like to tell people to do instead of cranking the timing up.
Have you put fresh plugs in it and pulled them at the end of the track or towed it back to know what's really going on?
That dual plane intake is also going to be really bad with fuel distribution and I'd bet that at that boost level you have one or more hot cylinders. Single plane will help tremendously.
I would look into methanol injection. Run 75 meth/25 water or even more methanol than that. I saw the same reduction in IAT's with 50% water as I did with 25% water at the boost level I was running. Although now that I think about it with your A2W intercooler your IAT's are going to be way lower than ambient anyways and that being said I would run 100% methanol for all the added octane you could possibly get.
You would be able to run the same amount of timing and more boost with the methanol injection which is what I like to tell people to do instead of cranking the timing up.
Best and safest bang for a monthy race is to drain the tank once a month, put a few gallons of 116 in it and crank the boost up a couple of psi at a time while watching the plugs and tune and et. 20psi and 18 degrees is asking for 116 now.
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Thread Starter
On The Tree
Joined: Mar 2010
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From: SpringCity Tn
So if I drained tank. Put some 112 in. changed intake to single plane with same timing curve/boost the motor should pick up more power? The motor never skips a beat. its strong. I have not been able to shut motor down after run and check plugs. but I keep it pretty fat on fuel. 11.2-11.7 a/f
the afr gauge takes samples from all the cylinders on that bank, so you could have one cylinder going lean but the other three are seeing more then they need which in return shows the afr is right per that hole bank.
reading individual plugs tells you each cylinder
reading individual plugs tells you each cylinder
Thread Starter
On The Tree
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From: SpringCity Tn
Ya I understand the a/f readings. and I know a few cyl are hotter than others by heat gun. I just need to squeeze some more et out of it. I qualified #2 last event. I would like to go back and win.
Teching In
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mixing pump gas with race gas I'd also recommend using Shell's unleaded race fuel (URT Advanced, google it) instead of leaded 116.
It has a higher detonation resistance than VP C16, but tighter idle and burn characteristics (so you won't lose throttle response, low end torque, or end up with a choppy idle). It also won't harm your cats or O2's.
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From: Norn Iron
I'm sure people have blown engines on race fuel ?
I really dont see much difference
I assume people tune their cars to push as far as they can afford with their setup. I dont see much wrong with pump fuel as long as some common sense is used.
But in this instance, 20psi with 9:1 and 18deg of timing on pump does sound very risky. Although if no knock can be heard and EGT's remain ok, then there really isnt much wrong with it.
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On The Tree
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From: SpringCity Tn
Current setup is strong guys. I've ran this for half the season now. I just needed a direction to go forward and pick up another 2-3 tenths. I've got the motor and supporting mods. just was curious what some of you high hp more experienced guys would suggest. I'm close just need a little more.
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From: Norn Iron
In that case, some race fuel, more boost and maybe a little more timing is probably the cheapest option.
At least giving it a try anyway.
Or what is very popular here in the UK among Subaru owners and also very cheap. Mix around 15% methanol with your pump fuel and re-tune
Some do vary the amount between 10-20%, 20% seems a lot to me though.
But it does usually yield more power from allowing more timing to be used on an engine that was knock limited due to fuel limitations, or more boost/same timing etc.
But you must re-tune, as adding the methanol to the fuel will see mixtures go lean unless you increase fuelling.
At least giving it a try anyway.
Or what is very popular here in the UK among Subaru owners and also very cheap. Mix around 15% methanol with your pump fuel and re-tune
Some do vary the amount between 10-20%, 20% seems a lot to me though.
But it does usually yield more power from allowing more timing to be used on an engine that was knock limited due to fuel limitations, or more boost/same timing etc.
But you must re-tune, as adding the methanol to the fuel will see mixtures go lean unless you increase fuelling.
While a 1.42 60ft is nothing to complain about, maybe a little more details on the car like tires, suspension, gear ratio, ect- might result into some more solutions.
Just by changing tire compound/size, some suspension work can save you a few 10ths, and with out changing anything on the motor. And adding second small 2 or 3 gallon fuel cell with race gas for track days couldnt hurt.
Maybe what I trying to say is if the motor is doing a good job now, look at other options other than the motor for quicker times....
Just by changing tire compound/size, some suspension work can save you a few 10ths, and with out changing anything on the motor. And adding second small 2 or 3 gallon fuel cell with race gas for track days couldnt hurt.
Maybe what I trying to say is if the motor is doing a good job now, look at other options other than the motor for quicker times....