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March 08, 2021, 06:28:55 AM

Prowler - Corvair (under construction

This is a discussion for the topic Prowler - Corvair (under construction on the board Members Buggies.

Author Topic: Prowler - Corvair (under construction  (Read 6218 times)

this user is offline snoopy

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Reply #105 on: January 26, 2021, 08:31:35 AM
A lot of quality work going into that buggy  ;-)up


this user is offline JonFuller

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Reply #106 on: January 26, 2021, 09:24:09 AM
For some clarity, here is a rough sketch of the fuel system.





this user is offline JonFuller

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Reply #107 on: January 26, 2021, 09:52:42 AM
For anyone interested, the purge tank pictured is basically there to eliminate any air that finds it way in to the system, as air would cavitate the Hi Pressure fuel pump, and cause all manner of air locks and cavities in the injection system if not disposed of.

Like most of the custom bits I'm making for it, It is fabricated from 304 Stainless steel.

I will use the existing Facet, 28gph/8psi ProFlo fuel pump to deliver fuel to the purge tank.

The engine has a theoretical max consumption of about 14gph @ WOT max RPM, so hopefully the facet pump, even with the restrictions of dragging fuel along pipes and through fittings etc will at least match, and hopefully exceed this figure. The lift pump only needs to deliver the amount of fuel the engine actually burns, because the hi pressure regulated circuit has it's return from the reg ALSO going to the purge tank, so that circuit will whizz round, and only the fuel actually burnt by the engine will need to be replaced by the lift pump, which is constantly trying to overfill the purge tank. 

Obviously, the amount of time the engine will realistically spend at WOT/max rpm is very small, but that's the worst case scenario I need to accommodate for.

The purge tank sits vertically, with a 16mm outlet feeding directly into the Bosch 044 hi pressure pump from an outlet positioned low on the purge tank. A stainless steel wool fills the lower half of the tank as a baffle. the two inputs to the purge tank, ie, the low pressure feed from the lift pump, and the bleed off from the hi Press regulator return, enter from the bottom of the purge tank, but have vertical tubes that run up through the SS wire wool to deliver the fuel to the space above the baffle wire (pictured), any air bubbles would find it hard to get down to the outlet to the Hi Press pump, even with the most vigorous shaking, as the SS wire baffle acts like a sponge (A stainless steel, fuel resistant sponge).

The position of these feeds into the purge tank (entering via the bottom) is purely for convenience, to simplify the general pipework arrangement/layout.

Air bubbles will head up to the top of the purge tank via these tubes, and exit via the (baffled) return line back to the main fuel tank.

So, there are effectively two circuits running, both sharing the purge tank. Any air gets sent back to the main tank once separated by the purge tank, ensuring the Hi Pressure pump always gets a good supply of un-airyated fuel, by effectively 'self bleeding'.

The purge tank will run at a low pressure, created by the slight restriction of the return line.
As long as the lift pump is trying to shove more fuel into the purge tank, than is being burnt by the engine, the purge tank will stay at a (slight) positive pressure, quickly disposing of any air bubbles via the top outlet back to the tank.

The lift pump will run whenever the ign is on, to prime the low pressure system, and the Hi Press pump is controlled by the ecu and runs whenever it sees fit (a few seconds when you switch the ign on to establish rail pressure, then continuously once the ecu sees a tach input)

Low press feed from tank is 8mm, return is 5mm, so a slight restriction exists on the return which will maintain a positive (allbeit low) pressure in the purge tank.

The stainless wire wool, is actually a couple of stainless washing up scourers from Tesco, they're just the right density. :)

Hopefully, my garbled words and state of the art CAD drawing make sense.
« Last Edit: February 22, 2021, 12:49:36 AM by JonFuller »


this user is offline Dave DND

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Reply #108 on: January 26, 2021, 10:43:42 AM
Brilliant explanation,

I was just about to ask what you have  just explained   ;-)up
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this user is offline Paul1953

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Reply #109 on: January 26, 2021, 11:19:17 AM
This is the sort of stuff that keeps me awake just about all night.  (maybe I shouldn`t read it   ;D ;D)

Just wish I had a lathe . tig welder, milling machine etc etc. oh yes   and a warm double space garage  ;-)up ;-)up


this user is offline JonFuller

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Reply #110 on: January 26, 2021, 11:32:27 AM
Just wish I had a lathe . tig welder, milling machine etc etc. oh yes   and a warm double space garage  ;-)up ;-)up

Well I did have to acquire them, they didn't just appear. :-/

PS. my workshop is ferkin freezing atm!
« Last Edit: January 26, 2021, 11:50:17 AM by JonFuller »


this user is offline Paul1953

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Reply #111 on: January 26, 2021, 01:16:07 PM
Well I did have to acquire them, they didn't just appear. :-/

Ha ha   understand that...  I have left it far too late.... my £156 per week state pension doesn`t go far so for you youngsters out there... don`t wait until it`s too late..... even if it means selling the wife to raise the cash,,, ;D ;D


this user is offline Hugh

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Reply #112 on: January 26, 2021, 01:29:06 PM
... don`t wait until it`s too late..... even if it means selling the wife to raise the cash,,, ;D ;D
[/quote]

Well Paul you won't get much for a second hand wife hereabout:






£1.20 in new money...plus a bowl of punch
Hugh


this user is offline JonFuller

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Reply #113 on: January 26, 2021, 07:36:40 PM

Ha ha   understand that...  I have left it far too late.... my £156 per week state pension doesn`t go far so for you youngsters out there... don`t wait until it`s too late..... even if it means selling the wife to raise the cash,,, ;D ;D

More than I've earned since last February! Bloody Covid :(

I spose it's given me the time to build this thing.


this user is offline Paul1953

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Reply #114 on: January 27, 2021, 08:56:34 AM
... don`t wait until it`s too late..... even if it means selling the wife to raise the cash,,, ;D ;D

Well Paul you won't get much for a second hand wife hereabout:






That`s me out of luck them...   Stay safe Hugh..


£1.20 in new money...plus a bowl of punch
[/quote]


this user is offline JonFuller

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Reply #115 on: January 27, 2021, 03:59:57 PM
Spent today assembling a spare/backup ecu.
A lot quicker the second time!













« Last Edit: January 27, 2021, 06:58:29 PM by JonFuller »


this user is offline JonFuller

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Reply #116 on: January 27, 2021, 04:01:18 PM
.

« Last Edit: January 27, 2021, 11:41:53 PM by JonFuller »


this user is offline JonFuller

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Reply #117 on: January 28, 2021, 06:24:54 PM
Made up the bits today to measure the flow rate of the Yamaha injectors.
The way they’re held / sealed by the throttle boddies meant I had to make a little rig for firing one separately into a measuring burette.

Turned an injector holder/hose tail out of some Brass hexagon bar I had laying about.  Worked a treat.

Luckily, all looks fine, 280cc/min @ 50 psi :)













« Last Edit: January 30, 2021, 08:04:14 PM by JonFuller »


this user is offline JonFuller

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Reply #118 on: January 29, 2021, 05:47:09 PM







« Last Edit: January 29, 2021, 06:23:05 PM by JonFuller »


this user is offline JonFuller

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Reply #119 on: February 02, 2021, 08:45:53 PM
Made up the engine efi loom today, and ran some bench tests...

TPS:

https://youtu.be/yl3AgfcmGfo

Idle Stepper Motors cycle:

https://youtu.be/qlzDHT1BlDk

Slow injector test:

https://youtu.be/p8IrgIDINck

Fast injector test:

https://youtu.be/iFqtkh_pYMI
« Last Edit: February 02, 2021, 08:53:14 PM by JonFuller »