Stock VW/Porsche injector figures Do add up

With Turbo and Super charging you can create massive horsepower with vw motors.

Moderator: seabeebuggy

User avatar
theKbStockpiler
Posts: 423
Joined: Sun Jul 15, 2012 12:25 pm

Stock VW/Porsche injector figures Do add up

Post by theKbStockpiler » Sat Mar 24, 2018 8:57 pm

If I use the info from this page on the 914 1.8 injectors http://users.erols.com/srweiss/tableifc.htm and use a injector calculator that includes a turbo option, I would be short about 6lbs an hour for 200hp.

From what I read in forums the porshe 914 injector ; which is close to the stock injected beetle injector, it's way too small.

Is it because the factory ECU used a low duty cycle or what else could it be?

Thanks for your expertise!
Super beetle with attitude

Clonebug
Posts: 3396
Joined: Fri Feb 16, 2007 12:28 am

Re: Stock VW/Porsche injector figures Do add up

Post by Clonebug » Sun Mar 25, 2018 12:17 am

When you figure injector size you need to calculate at 80% Duty Cycle. That is what most sites say is max rating for a N/S or turbo setup to give enough safety factor and overhead.

For 200 hp you would need four 32# injectors at 80% Duty Cycle. Those same injectors will support 230 hp at 100% DC.

I used 32 lb./hr. injectors for my 1679 and was hitting 103% DC with them.
I now use 45 lb./hr. injectors on the same engine and will see 73-76% DC at 22-24 lbs. boost.

You would be better off picking an injector that will support a higher max hp than you think you might ever need to save yourself from having to buy them twice.
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.

User avatar
theKbStockpiler
Posts: 423
Joined: Sun Jul 15, 2012 12:25 pm

Re: Stock VW/Porsche injector figures Do add up

Post by theKbStockpiler » Sun Mar 25, 2018 5:16 pm

From the chart I posted and the online calculators they are rated at 180hp at %80 duty cycle.



From this PelicanParts forum;
http://forums.pelicanparts.com/porsche- ... wners.html
The builder feels that they are way undersized but I have to assume this is because of the stock system with a low duty cycle.
Super beetle with attitude

Clonebug
Posts: 3396
Joined: Fri Feb 16, 2007 12:28 am

Re: Stock VW/Porsche injector figures Do add up

Post by Clonebug » Sun Mar 25, 2018 10:36 pm

You can use any injector you desire if you have a way to log a run so you can see what kind of DC you are getting. I saw mine at 95% and more a few times when I revved it out farther than I usually do. I found the larger ones for a really great price so it was a no brainer to change them out during my winter upgrade.
I'm good to about 360 hp now.
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.

User avatar
andy198712
Posts: 1723
Joined: Wed Apr 13, 2011 3:01 pm

Re: Stock VW/Porsche injector figures Do add up

Post by andy198712 » Mon Mar 26, 2018 1:36 pm

also the DC is only as accurate as the figures you put in so just make sure you have everything correct and your math will be golden :)

User avatar
theKbStockpiler
Posts: 423
Joined: Sun Jul 15, 2012 12:25 pm

Re: Stock VW/Porsche injector figures Do add up

Post by theKbStockpiler » Mon Mar 26, 2018 9:48 pm

I got it figured out. It's because only one bank of injectors can be pulsed at a time with the D-jet.
They had to be too big for a modern systems standards. I have been reading all of the articles I can because I wan't to modify a D-jet and It just hit me.
Super beetle with attitude

User avatar
MarioVelotta
Posts: 3814
Joined: Wed Mar 12, 2003 3:01 am
Location: Monroe, Wa.
Contact:

Re: Stock VW/Porsche injector figures Do add up

Post by MarioVelotta » Mon Mar 26, 2018 10:05 pm

Just because it is bank fire would not change the injector size requirements.
The Dub Shop
Mario@thedubshop.net
2276 Turbo - 92 Octane
11.537 @ 115.74mph - 15psi
1600 S.C. - 92 Octane
15.47 @ 83mph - 13psi
1600 NA ITB - 18sec :lol:
Facebook-Tech-Store

User avatar
theKbStockpiler
Posts: 423
Joined: Sun Jul 15, 2012 12:25 pm

Re: Stock VW/Porsche injector figures Do add up

Post by theKbStockpiler » Mon Mar 26, 2018 11:23 pm

MarioVelotta wrote: ↑
Mon Mar 26, 2018 10:05 pm
Just because it is bank fire would not change the injector size requirements.
So how is that physically possible if you don't mind explaining? :?
Super beetle with attitude

User avatar
MarioVelotta
Posts: 3814
Joined: Wed Mar 12, 2003 3:01 am
Location: Monroe, Wa.
Contact:

Re: Stock VW/Porsche injector figures Do add up

Post by MarioVelotta » Tue Mar 27, 2018 12:05 am

In bank fire applications the injector is opened twice during an engine cycle instead of once like with sequential. The same amount of fuel is delivered, just not at an optimized time.
The Dub Shop
Mario@thedubshop.net
2276 Turbo - 92 Octane
11.537 @ 115.74mph - 15psi
1600 S.C. - 92 Octane
15.47 @ 83mph - 13psi
1600 NA ITB - 18sec :lol:
Facebook-Tech-Store

User avatar
theKbStockpiler
Posts: 423
Joined: Sun Jul 15, 2012 12:25 pm

Re: Stock VW/Porsche injector figures Do add up

Post by theKbStockpiler » Tue Mar 27, 2018 10:33 pm

Where can I find this explained in a D-jet system? I have not seen it stated as of yet.
Super beetle with attitude

User avatar
panel
Posts: 3715
Joined: Sun Sep 24, 2000 2:01 am
Location: Victoria B.C. Canada
Contact:

Re: Stock VW/Porsche injector figures Do add up

Post by panel » Tue Mar 27, 2018 10:40 pm

I don't think Mario is saying it's D-Jet specific.......that's just the characteristics of injectors re duty cycle. What mods are you doing to the D-Jet ?

https://oldtimer.tips/en/d-jetronic/52-overview
Subaru JDM EJ20 Turbo bus
Built by Germans powered by Japanese and brought together by Canadians

User avatar
theKbStockpiler
Posts: 423
Joined: Sun Jul 15, 2012 12:25 pm

Re: Stock VW/Porsche injector figures Do add up

Post by theKbStockpiler » Wed Mar 28, 2018 3:06 pm

I was reading the PelicanParts forum thread on using a D-jet with a turbo and I don't think the author understood some of the fundamentals of a D-jet.
I want to at least use a 914 D-jet system as a starter FI system for a 1904 type I and then try to make a PowerBox and use it with a turbo.

I'm going to flood my head with as much of the D-jet system as is possible and then try to come up with a few ideas like:

1-Keeping it all analog but substituting the MAP with a different circuit that will enrich it on boost.
2-Substituting one sensor and grafting in a MicroController to enrich on boost ,and add a O2 sensor to keep it within a specified A/R at all times.
Super beetle with attitude

Clonebug
Posts: 3396
Joined: Fri Feb 16, 2007 12:28 am

Re: Stock VW/Porsche injector figures Do add up

Post by Clonebug » Wed Mar 28, 2018 10:38 pm

Sounds like a great way to get a big headache.

There is sooo much out there that will ease the frustration of a FI turbo setup. Working on them gets old after a while.
It really is fun to just drive them.
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.

User avatar
theKbStockpiler
Posts: 423
Joined: Sun Jul 15, 2012 12:25 pm

Re: Stock VW/Porsche injector figures Do add up

Post by theKbStockpiler » Thu Mar 29, 2018 10:18 am

The plan is to remove/disable the turbo and just drive on the stock D-jet so I'll only be experimenting with it on a part time basis. I really should install a cutout before the turbo. :lol: I'm sure I won't get it right the first time.

I have been a computer/electronics hobbyist for years and I really don't like complicated garbage that you don't fully understand and are held for ransome by a corporation that makes it that way. In the event I get tired of it I'll try a blowthrough SU system.
Super beetle with attitude

User avatar
panel
Posts: 3715
Joined: Sun Sep 24, 2000 2:01 am
Location: Victoria B.C. Canada
Contact:

Re: Stock VW/Porsche injector figures Do add up

Post by panel » Thu Mar 29, 2018 6:33 pm

theKbStockpiler wrote: ↑
Thu Mar 29, 2018 10:18 am
I have been a computer/electronics hobbyist for years
....and you're not running Megasquirt yet ?
Subaru JDM EJ20 Turbo bus
Built by Germans powered by Japanese and brought together by Canadians

Post Reply