There have been multiple threads that have discussed the replacement of the OEM Viper in-the-bottle fuel pump with either an external or a double and triple pump in the tank with custom hangers. I took another route and installed a Gen 3 pump into a 1997 Gen 2 . The pump was installed into the 1997 OEM bottle. I took some notes and pictures during the install, the following are some observations. Let me preface this by saying I am by no means a fuel pump expert, what follows are my observations and some easily substantiated calculations.
Some may be surprised, however, if you add a Boost-A-Pump (BAP) to a 255 liter/hr pump you can maintain approximately 850 hp.
If anyone wants to add to or correct this post please feel free. This write-up assumes the Gen 2 has a 190 LPH pump and the Gen 3 has a 255 LPH pump.
1. THE OEM FUEL SYSTEM
The viper OEM fuel set-up is a two stage pump in a bottle that sits inside the tank. The bottle acts as a reservoir and keeps the fuel supplied to the engine during acceleration when fuel is low in the tank. Several high power cars have the same set-up, Mustangs and Camaro’s are some examples..
The pick-up tube that extends out of the pump and fits into the bottom of the bottle pulls fuel from the bottom of the tank and fills the bottle, There is a pick-up orifice closer to the pump body that supplies the engine. There is a donut/washer on the inside bottom of the bottle that the pump sits on, that washer keeps the fuel trapped in the bottle. Under normal operating conditions the bottle is always full, therefore, acting as a reservoir that keeps the fuel flowing during hard straight-ahead acceleration or hard cornering, especially when the tank is less than ½ full.
The tank is approximately 10"H x 29"W x 18"D. It is almost a true rectangle, with a dog **** shape to the rear and a bubble on the front. The bottle sits close to the center of the tank. The bottle pick-up sits directly on the bottom of the tank. When my gauge says ½ full, the fuel is 4" above the bottom. From the dimensions and the bottle location it is easy to see how the fuel pick-up can go dry during acceleration or cornering if the bottle did not act as a reservoir.
2. THE Gen 2 VIPER FUEL PUMP HAS LIMITATIONS
If you look at the following table, the 190 LPH pump is not capable of much more than 500 NA rwhp, a key exception would be a nitrous car. Higher hp NA applications might also work, but, at reduced fuel pressure, therefore, requiring some tricky a/f tuning. If you remove my 10% safety margin from the table the 190 LPH pump might give you 525 rwhp for a NA car. If a little tuning you might go a bit higher. A nitrous car could probably exceed 600 hp. The point is the hp is limited by the 190 LPH fuel pump. All these are border line and you are walking the edge. When I ran a single stage nitrous at 625 hp I could not hit my target a/f of 11.5, the car just ran out of fuel pump.
Please keep in mind this table is theoretical, however, the basis is manufacturer’s data, the variable is the car fuel system set-up. Use the table as a starting point, but, consult your tuner for a final solution. The input data for this table came from the Kenne Bell website and the Auto Performance Engineering website
Some may be surprised, however, if you add a Boost-A-Pump (BAP) to a 255 liter/hr pump you can maintain approximately 850 hp.
If anyone wants to add to or correct this post please feel free. This write-up assumes the Gen 2 has a 190 LPH pump and the Gen 3 has a 255 LPH pump.
1. THE OEM FUEL SYSTEM
The viper OEM fuel set-up is a two stage pump in a bottle that sits inside the tank. The bottle acts as a reservoir and keeps the fuel supplied to the engine during acceleration when fuel is low in the tank. Several high power cars have the same set-up, Mustangs and Camaro’s are some examples..
The pick-up tube that extends out of the pump and fits into the bottom of the bottle pulls fuel from the bottom of the tank and fills the bottle, There is a pick-up orifice closer to the pump body that supplies the engine. There is a donut/washer on the inside bottom of the bottle that the pump sits on, that washer keeps the fuel trapped in the bottle. Under normal operating conditions the bottle is always full, therefore, acting as a reservoir that keeps the fuel flowing during hard straight-ahead acceleration or hard cornering, especially when the tank is less than ½ full.
The tank is approximately 10"H x 29"W x 18"D. It is almost a true rectangle, with a dog **** shape to the rear and a bubble on the front. The bottle sits close to the center of the tank. The bottle pick-up sits directly on the bottom of the tank. When my gauge says ½ full, the fuel is 4" above the bottom. From the dimensions and the bottle location it is easy to see how the fuel pick-up can go dry during acceleration or cornering if the bottle did not act as a reservoir.
You must be registered for see images attach
2. THE Gen 2 VIPER FUEL PUMP HAS LIMITATIONS
If you look at the following table, the 190 LPH pump is not capable of much more than 500 NA rwhp, a key exception would be a nitrous car. Higher hp NA applications might also work, but, at reduced fuel pressure, therefore, requiring some tricky a/f tuning. If you remove my 10% safety margin from the table the 190 LPH pump might give you 525 rwhp for a NA car. If a little tuning you might go a bit higher. A nitrous car could probably exceed 600 hp. The point is the hp is limited by the 190 LPH fuel pump. All these are border line and you are walking the edge. When I ran a single stage nitrous at 625 hp I could not hit my target a/f of 11.5, the car just ran out of fuel pump.
Please keep in mind this table is theoretical, however, the basis is manufacturer’s data, the variable is the car fuel system set-up. Use the table as a starting point, but, consult your tuner for a final solution. The input data for this table came from the Kenne Bell website and the Auto Performance Engineering website
190L Pump (Gen 2) | L/hr | Gal/hr | lbs/hr | lbs/hr w/Safety Margin -10% | Max NA Flywheel HP (BSFC = .45) | Max NA RWHP | Max Boosted Flywheel HP (BSFC = .60) | Max Boosted RWHP | Max Kenne Bell Boosted Recommendation |
12V | 123 | 33 | 205 | 185 | 410 | 349 | 308 | 261 | |
13.5V | 161 | 43 | 268 | 242 | 537 | 456 | 403 | 342 | |
17.5 | 203 | 54 | 338 | 305 | 677 | 575 | 508 | 431 | |
255L Pump *(Gen 3) | L/hr | Gal/hr | lbs/hr | lbs/hr Safety Margin -10% | Max NA Flywheel HP | Max NA RWHP | Max Boosted Flywheel HP | Max Boosted RWHP | |
12V | 208 | 55 | 346 | 312 | 692 | 589 | 519 | 441 | |
13.5 | 246 | 65 | 410 | 369 | 819 | 696 | 614 | 522 | |
17.5V | 351 | 93 | 584 | 526 | 1168 | 993 | 876 | 745 | |
20V | 440 | 116 | 732 | 659 | 1465 | 1245 | 1099 | 934 | 750-850 |
1. Based on 50 psi. | |||||||||
2. BSFC can vary dramatically on supercharged applications. |