Parallel fuel system with pulsation dampers. Check it out.
03-11-09, 07:02 PM
#26
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http://www.sx-performance.com/15402.PDF
"We use Fluorosilicone diaphragm material, formally used only on aerospace components. This material is capable of long life (longer than competitor's Nitrile or rubber based "cheap" diaphragms), and has a high resistance to chemical attack.
Light weight diaphragm allows the regulator to act as an accumulator. Not only does this feature help prevent system chatter and noise, but also acts as a pulsation dampener, to help maintain consistent fuel pressure."
Marren products are not aerospace grade, and therefore pulsation dampeners are probably a good idea if you use their cheaper components.
03-12-09, 12:44 PM
#29
I too use the Marren Damper with an SX Pressure Regulator. I do not have dual feed fuel lines thus only use the single Damper however; I too would have put in two dampers if I used a parallel dual feed system, based on experience in my past life as a hydrodynamicist.
I stayed single feed only due to: 1) I am not running the power or flow rates to justify and 2) as a consequence of 1 (staying sequential et.al.), I do not have the room for such gear. As it is, I went down a simple path of just upgrading injectors, I decided I’ll refresh the engine bay fuel system with all new OEM parts while under the UIM. Then went to what the hell another $1,500 later (after spending $1600 just on new injectors (MMS), mod’s by RC and independent flow testing by Yaw Power) with one simple hell as I am down here may as well upgrade the OEM Pulsation Damper. Now gone to FPR, Goodridge Super flex 910 Kevlar w/ Teflon smooth bore fuel lines, etc, etc.
As to a Pulsation Damper need in an RX-7; who really knows .. but I will add these comments:
1) our cars run high rpms, creating very high frequency injector pulsing,
2) they batch fire, again increasing pulsation frequencies,
3) the primary and secondary rails are separated so even if the FPR provides some high frequency damping (it obviously does low frequency by its very nature) it is a very long way from stopping primary pulses from creating shock waves,
4) Mazda tried to save weight and $ in this cars development. The engineers could have easily given up the PD to save on both accounts but they held out for its need and maybe the accountants influence created the use of a PD without a 10-15 year life,
5) Not every EFI car uses a PD but many hi performance cars do including models by Porche and BMW.
I stayed single feed only due to: 1) I am not running the power or flow rates to justify and 2) as a consequence of 1 (staying sequential et.al.), I do not have the room for such gear. As it is, I went down a simple path of just upgrading injectors, I decided I’ll refresh the engine bay fuel system with all new OEM parts while under the UIM. Then went to what the hell another $1,500 later (after spending $1600 just on new injectors (MMS), mod’s by RC and independent flow testing by Yaw Power) with one simple hell as I am down here may as well upgrade the OEM Pulsation Damper. Now gone to FPR, Goodridge Super flex 910 Kevlar w/ Teflon smooth bore fuel lines, etc, etc.
As to a Pulsation Damper need in an RX-7; who really knows .. but I will add these comments:
1) our cars run high rpms, creating very high frequency injector pulsing,
2) they batch fire, again increasing pulsation frequencies,
3) the primary and secondary rails are separated so even if the FPR provides some high frequency damping (it obviously does low frequency by its very nature) it is a very long way from stopping primary pulses from creating shock waves,
4) Mazda tried to save weight and $ in this cars development. The engineers could have easily given up the PD to save on both accounts but they held out for its need and maybe the accountants influence created the use of a PD without a 10-15 year life,
5) Not every EFI car uses a PD but many hi performance cars do including models by Porche and BMW.
03-12-09, 01:32 PM
#30
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Very nice setup, there's a good writeup about parallel fuel setups on TeamFC3S and needing FPD's. Only thing to add is I think it would be more advantageous to have the FPD's on the feed side, and having the FPR on the return side, you would get the best of both and never have an issue. I'm sure that many FPR's do have pulsation dampening built in to them, but it's not what they're designed to do and wouldn't do as proper of a job as a dedicated FPD. This is just my opinion, I don't have any facts about FPR's abilities to damper pulsations.
03-13-09, 12:29 AM
#31
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Thanks for the compliment. My original plan was to mount the PD's directly to the end of the rails, but there is not enough room. On the front the water neck was to close and at the back the firewall was to close. ( secondary rail of course ) So I called Marren about mounting them remotely like I did. They said that you can plumb them on either side of the rails, but they are more efficient if plumbed after the rails. Since it was easier to mount them to the firewall, it worked out best to do like they said and go after the rails. I have heard of them being plumbed before the rails and they do their job that way too.
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