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Walbro gss342

Turboflash said:
There's allot more to keeping deto at bay than just octane. Every "tune" starting at stock level and going on up needs certain things to prevent deto. First, the map has to be right (usually developed from lots of hours on dyno). Right means right boost, right timing, right injectors (capacity), right injector pulse, right engine cooling, right inter-cooler,etc. One can make up for too low octane (to a certain point) by richer fuel mixture. Or, running Boostane. As far as bigger pump preventing deto, that is not necessarily true if there are other issues like boost leaks, engine with too high compression, too much timing, injectors too small, coolant temps too high, IAT too high, etc. Every tune is engineered to run at a certain fuel pressure (stock 998s = 43 psi, key on engine not running). As long as the pump can keep the fuel pressure rail at the right psi, assuming everything else is right, then all should be ok. However if the fuel pump can't keep up with demand, then the AF ratio will get leaner and deto will likely result. No doubt bigger tunes need more fuel delivery. I've always heard that stock fuel pump is ok up to about 270HP. IDK. Keep in mind, the 998 turbo system is a boost reference system meaning that fuel pressure goes up and down like boost does. For every 1 lb of boost added, fuel pressure will also increase 1 lb. At some point, the injectors aren't big enough (volume-wise) to delivery enough fuel within the allowable pulse width the ECU has to work with.
When in doubt, a bigger fuel pump is a good idea IMO. Fuel not needed by the injectors is just returned to tank via the return line. Raising octane via Boostane IMO is also not a bad idea. Raising octane even 2-3 points (from pump 91 or more) does help prevent deto. Lots of guys who data log can see the difference Boostane makes.
Not sure about TD and Hurricane's biggest pump tunes, but for my Stage 4 PEFI tune (330 HP), I have to run fuel pressure at 58 psi (key on engine not running) in order for stock injectors to flow enough to keep engine fed adequately. So an adjustable FPR is also handy. You can richen whole fuel map by just increasing FP a few pounds.
Click to expand...
I definitely overlooked some important criteria in what I tried to make a very black and white question. Lol.
TD is requesting 100 octane on both Max19 & Max20. Obviously boost and timing are near the ceiling. Claims of guys running 93 octane on those tunes is possible. With more fuel, boostane, etc.
The question I have is you can put a higher PSI pump in there, but if The regulators controlling it I'm not sure exactly how it would help?
And I think you answered that question in that the regulator is boost referenced, that is if you have a pump that can supply the needed volume.
Again I'm assuming at that level of performance the factory fuel pump is substantially questionable.
 

The upgraded pump is not for higher pressure, it’s for higher volume. At higher pressures these pumps lose volume. A larger pump can deliver more volume at higher pressure demands. Your fuel pressure increases by one psi per psi of boost. The fuel pressure regulator on the sleds is rising rate, and that is what increases the pressure in relation to the boost. The Mike that commented on your Facebook post and said the tune was rated at 94 octane with a large pump is Mike at TD so you can trust his recommendation. Of course, there are always other factors to consider and yes, data logging is a great idea always, but especially on bigger tunes. It really gives you an inside. Look at things and helps to determine if the fuel you are using for what you are trying to accomplish is adequate or not.
 
justinator said:
The upgraded pump is not for higher pressure, it’s for higher volume. At higher pressures these pumps lose volume. A larger pump can deliver more volume at higher pressure demands. Your fuel pressure increases by one psi per psi of boost. The fuel pressure regulator on the sleds is rising rate, and that is what increases the pressure in relation to the boost. The Mike that commented on your Facebook post and said the tune was rated at 94 octane with a large pump is Mike at TD so you can trust his recommendation. Of course, there are always other factors to consider and yes, data logging is a great idea always, but especially on bigger tunes. It really gives you an inside. Look at things and helps to determine if the fuel you are using for what you are trying to accomplish is adequate or not.
Click to expand...
I sure hope I didn't saying anything too stupid to him ...ugh! Lol.
 
jtmetal said:
I definitely overlooked some important criteria in what I tried to make a very black and white question. Lol.
TD is requesting 100 octane on both Max19 & Max20. Obviously boost and timing are near the ceiling. Claims of guys running 93 octane on those tunes is possible. With more fuel, boostane, etc.
The question I have is you can put a higher PSI pump in there, but if The regulators controlling it I'm not sure exactly how it would help?
And I think you answered that question in that the regulator is boost referenced, that is if you have a pump that can supply the needed volume.
Again I'm assuming at that level of performance the factory fuel pump is substantially questionable.
Click to expand...
LOL. I get a laugh out of the tuners "requesting" 100 octane on their big "pump gas" tunes! 100 octane is not pump gas. And, where are you going to get 100 octane on the trail? To me, a tune sold as pump gas tune, runs on 91 safely. Of course, adding a little Boostane never hurts for added insurance.
 
Turboflash said:
LOL. I get a laugh out of the tuners "requesting" 100 octane on their big "pump gas" tunes! 100 octane is not pump gas. And, where are you going to get 100 octane on the trail? To me, a tune sold as pump gas tune, runs on 91 safely. Of course, adding a little Boostane never hurts for added insurance.
Click to expand...
Kills me too...lol. Those two tunes are on the edge of reality. I've got them loaded in my sled, but will need to evaluate what needs to be done. I think the pump and/or fuel regulator will suffice in order to run pump. And like you say turboflash, a little boostane doesn't hurt one bit.
So, I've got a 280tune that supposedly runs on pump. But you know how that goes. Lol
 
Turboflash said:
LOL. I get a laugh out of the tuners "requesting" 100 octane on their big "pump gas" tunes! 100 octane is not pump gas. And, where are you going to get 100 octane on the trail? To me, a tune sold as pump gas tune, runs on 91 safely. Of course, adding a little Boostane never hurts for added insurance.
[/QUO
Click to expand...
 
jtmetal said:
Kills me too...lol. Those two tunes are on the edge of reality. I've got them loaded in my sled, but will need to evaluate what needs to be done. I think the pump and/or fuel regulator will suffice in order to run pump. And like you say turboflash, a little boostane doesn't hurt one bit.
So, I've got a 280tune that supposedly runs on pump. But you know how that goes. Lol
Click to expand...
Agree. I run .26 oz/gallon to supposedly end up with about 95 octane (according to Boostane mixing chart). I carry 2 oz glass bottles in my pocket and put it in at every fill. Seems to work. KnappAttack says it does, so it must, LOL!
I have an AEM AFR gage on my handlebar that I watch religiously. Last year I was running a 300 tune but due to my higher-flowing exhaust, I had to crank up FP about 2-3 lbs to make WOT AFR safe in high 11's. This season I am running a supposed 320HP pump gas safe tune (yeah right). But with my 3" small-body Sandale though I'm betting I'll need same additional 2-3 lbs of FP to be safe, along with my usual dose of Boostane. What is 320 HP with a more-restrictive 2.5" muffler, compared to with a 3" higher-flowing muffler? 330? We'll see how it goes.
 
Turboflash said:
Agree. I run .26 oz/gallon to supposedly end up with about 95 octane (according to Boostane mixing chart). I carry 2 oz glass bottles in my pocket and put it in at every fill. Seems to work. KnappAttack says it does, so it must, LOL!
I have an AEM AFR gage on my handlebar that I watch religiously. Last year I was running a 300 tune but due to my higher-flowing exhaust, I had to crank up FP about 2-3 lbs to make WOT AFR safe in high 11's. This season I am running a supposed 320HP pump gas safe tune (yeah right). But with my 3" small-body Sandale though I'm betting I'll need same additional 2-3 lbs of FP to be safe, along with my usual dose of Boostane. What is 320 HP with a more-restrictive 2.5" muffler, compared to with a 3" higher-flowing muffler? 330? We'll see how it goes.
Click to expand...
What is the actual fuel pressure "key on" you are running?
I put an adjustable fuel press regulator on mine this year and I am starting with 48psi key on.
300hp header flash with 3" exhaust
 
sideshowBob said:
What is the actual fuel pressure "key on" you are running?
I put an adjustable fuel press regulator on mine this year and I am starting with 48psi key on.
300hp header flash with 3" exhaust
Click to expand...
With closed loop its not too fussy, ive cranked it fairly high in the past to see how it reacts and even though it richens the idle and a bit of low end before closed loop activates it has no ill effects on drivability likely due to the fact injector pulse width is so small at those rpms the increased fuel pressure has smaller effects. Once closed loop activates it will pull fuel if needed. 48 should be good starting point and adjust to where the closed loop isnt being overly active in either direction.
 
sideshowBob said:
What is the actual fuel pressure "key on" you are running?
I put an adjustable fuel press regulator on mine this year and I am starting with 48psi key on.
300hp header flash with 3" exhaust
Click to expand...
PEFI Stage 4 kit includes, amoung other parts, a 4-bar FPR. 14.7 x 4 = 58.8 psi on paper. However, that is with their 2.5" rather restrictive muffler. I have 3" small-body Sandale. I'm set at 61 psi, about 2-3 lbs more than PEFI 4-bar to cover my better flowing 3" muffler. I can adjust psi to what is safe.
 
Turboflash said:
PEFI Stage 4 kit includes, amoung other parts, a 4-bar FPR. 14.7 x 4 = 58.8 psi on paper. However, that is with their 2.5" rather restrictive muffler. I have 3" small-body Sandale. I'm set at 61 psi, about 2-3 lbs more than PEFI 4-bar to cover my better flowing 3" muffler. I can adjust psi to what is safe.
Click to expand...
That kit runs a lot of fuel pressure considering stock is 43.
 
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