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Just wished to make a clarification on the fuel pump differences between our in-line pump and the in-tank pumps used by other turbosystems.
I have noticed a tendency for board members to recommend the in-tank type over our in-line model. This may prove to be bad advice to give, as the following must be considered:
The commonly available pumps that install in-tank (replacing the stock pump) are by Walbro, and rated at 255 LPH. However, an important distinction: this volume is measured at 45 PSI delivery pressure. As pressure is increased, the volume the pump can supply falls off dramatically. This pump was never intended to provide the 100 PSI these systems need, and I believe it is dangerously close to maximum output, if not beyond, at 100 PSI.
When upgrading the factory turbo car, we steer away from the Walbros and use a Nippondenso pump (much more reliable, if a bit more expensive). Why not use the same pump for our RS/GS turbosystems? It has an internal relief valve that will not allow pressures above 85 PSI. Of course, as the factory turbo uses a 1:1 FPR, it would only need to provide 65 PSI pressure @ 20 PSI boost (45 PSI base +20). So it works well in the factory turbo cars with their lower fuel pressures.
As the above alternatives were therefore deemed inadequate for our turbosystems, we arrived at our current in-line setup. Our ACCEL pump is roughly twice the size of any in-tank pump. We also include relay/wiring/instructions to bring 12V to the pump from the battery, so as not to overload the factory wiring harness, as it was never meant for the current draw any of these pumps can pull at 100+PSI.
The combination of the stock in-tank pump feeding our correctly wired ACCEL pump has been proven safe up to the 475 HP our RS develops: read that carefully, that is PROVEN, not just theorized or "potential" conjectures. It has been an excellent, dependable setup. It is standard equipment in our Stage I and II systems, and is therefore also intentionally designed to allow higher Stages to be employed later without having to again re-engineer the fuel system. The extra capacity it gives Stage I and II owners is a plus, as it will be able to overcome some deficiencies such as a restricted filter or tank sock, low voltage, or anything else that can reduce pump output. Pumps that are already running at full output (like the in-tank) offer no such reserve potential, and results can be devastating if everything is not "just right" (which happens more often than you may think!).
Sure, it's a bit more expensive, and a little harder to install. But what is a ruined engine, or simply reduced performance, worth? We feel our approach is good insurance for our customers. Period. It's another way we have strived to make our systems as trouble-free over the long term as possible.
I am gonna go beat the ol' RS up on a drive home in 18 degree weather now. I love winter: the additional HP from the cold, dense air is addictive! Hope I find someone to play with tonite!
Bill Hahn Jr.
98 RS Turbo: 10.87 @ 136 MPH
HRC Stage V with N20
Nation's Fastest Street FWD 2G DSM
www.turbosystem.com
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