I have the stock Lo3 intank fuel pump and I'm playing with the idea of a 100hp shot but I'm already running 200% more hp than the stock engine and 150% more torque. Does anybody know of a way to check for good fuel pressure at WOT or know how much a stock intake fuel pump flows for the TBI systems?
Are all intank fuel pumps the same?

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, Jon (350 TBI!)
91 Red My website

 

Theres an excellent way to check that. Its called a fuel pressure gauge.



[This message has been edited by madmax (edited August 26, 2001).]

 

WOW!! you have 510hp and 425lb/ft of torque!?!?! I'd say that fuel pump is way out of it's league!!(I think you're percentage might be a bit off, but I could be wrong)

I'm sorry, but I don't know the lph of the stock pump, but for what it's worth Paxton sent me a higher volume in tank fuel pump with my S/C kit when I bought it. And they claim to to add 40%-50% more hp, which is about where I think I'm at. I Dyno'd 200.1 hp and 274.9 torque when I was running 15.2's. Since then I've added the 3.42's, posi and played with the timing to get my 14.4's. So if you're running more power than me or even the same I would suggest changing to a higher volume one.

Mike

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Car:
92 Formula
Stock 305 TBI and 700R4 trans
Mods:
7psi Paxton
Edelbrock Coated headers, high flow cat, Flowmaster catback
SLP takeoff posi, GM 3.42's
Nitto Drag Radials (245/50/16) on ARE road racing rims (8lbs lighter each)

Best 1/4 mile - 14.421 @95.96 w/a 1.983 60'

[This message has been edited by Blown 305 TBI (edited August 27, 2001).]

 

Blown, I think you need to go back and take some summer math class. Stock Lo3 engine made 170hp, 200% of that is 340hp and the stock Lo3 torque was 255, 150% of that is ~380. My engine is 330hp and 380 ft-lbs, I think my math is correct and I don't think this fuel pump is going to work.
I also don't think N2o kits come with fuel pumps, I wish they did. As for the fuel guage...how do you check the fuel pressure when the engine is under a load (1/4 mile run)? I think what I need to do is get a new intake walbro pump (255), a cowl hood, and a fuel pressure guage mounted in the scoop.
Can anybody else think of anything else I should get or need before doing the 100hp shot of go juice?

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, Jon (350 TBI!)
91 Red My website

 

340 is 200% OF stock...200% more than stock is 510. Semantics...but any excuse to bust someones chops goes around here Out of my own lame curiosity..how did you come up with that number? Dyno? Sounds pretty generous to me.

Use a fuel pressure gauge to test if it falls off. Get an isolaror and mount one in the cab, or add a big temporary excess length to the fuel line, and duct tape a gauge to the windshield.


However, if you are serious about nitrous..don't even mess around with stock style pumps. Do it right, drop the tank, put in a pickup, sump, or bulkhead fitting, and add an aftermarket inline pump.

FWIW, I drained my tank using a stock TBI pump once, it took bloody forever. I did it again later with my 140gph aftermarket...took less than 5min.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

Exactly.
I'm not trying to flame, just making a simple observation and correction.
Take a calculator, punch in 170, then hit the + button, then punch in 200, then hit the % button, you will get 510.
Either way I say you'll need at least a new higher volume in-tank pump or a nice in-line pump(which would be better in the long run IMHO)

Mike

[This message has been edited by Blown 305 TBI (edited August 27, 2001).]

 

Thanks for trying to make me look like an idiot (jerks) but really, I do appreciate the opinion that my stock pump is crap.
Why do you say an inline pump is better than an intank? Wouldn't the intank be better for a daily driver (winter and summer). I thought the intank pumps stay cooler because they use the gas as way to disapate heat while the inlines usually need heat sinks. Another rumor I heard (and believe) is that the intake pumps usually fail because the owner usually ran near empty more than full.
What do you guys recommend for a fuel pump. I plan on a little N2o and do NOT want to get a new fuel pump if I go to a higher pressure EFI system. What is the word about the Walbro (spelling ?) pumps and what is the link, I remember seeing posts about them and hearing nothing but good things.

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, Jon (350 TBI!)
91 Red My website

 

If you look at the intanks and the externals, they are not designed the same at all... the interal pumps are designed with the intent that fuel will be surrounding it to cool the pump, the externals are not designed that way.

I wouldnt risk it on a stock TPI pump if you were actually going to be making 440hp, I would be looking for something better. I'd call walbro and see if they make a low pressure intank pump that flows more than yours, no need in getting a pump that supplies that much extra pressure it will just heat up the fuel.