Carbs or FI? Please give me your opinions!

general_lee_jr · Post by **general_lee_jr** » Mon Jan 17, 2005 4:46 pm

OK, if you did not already know I am building a 2L Type 4 for my bug. The more I read I have come to the conclusion that FI is the way to go. I may be wrong but I am still a Type 4 noob. If I was looking to fuel my 2056cc which FI system should I look for and what are all the parts I need to aquire? IE, Is it better to get something from a vanagon or a trasporter or what? Thanks, Brad

Post by **Piledriver** » Mon Jan 17, 2005 10:02 pm

General, if you want EFI on an upright conversion, you have 2 fundamental choices:(more or less) followed by all the details...

CB throttle body EFI (or similar, looks like dual Webers)

A custom made plenum/runners that somehow clears the fan housing, and your choice of the half dozen or so aftermarket EFI setups,
or if you are feeling creative in a sawzall and welder kinda way, a refabbed stock setup.

The T4 stock EFI and Vanagon systems fit nice, work great, but they didn't have to route around a Doghouse fan shroud.

One could likely do something interesting with a stock TB/plenum on top of the fan housing, with nice long runners sorta like this:
(OK, it has no fan housing, but pretend there is)

http://shoptalkforums.com/viewtopic.php?t=82526

Tip---Put the injectors at the heads, like stock. That's where they belong, pointed right at the valves.

raygreenwood · Post by **raygreenwood** » Mon Jan 17, 2005 10:33 pm

Yeah...but look at that torque/hp graph. the volume on those runners...and the diameter...are so much too large...that under 3000 rpm...this engine is almost undrivable. Look at that HUGE burble...then the stumble....drops almost to the bottom of the scale. Great for drag racing? Yup!...but you will have to trailer it there

Ray

jonas_linder · Post by **jonas_linder** » Tue Jan 18, 2005 2:47 am

Ray >> that's burble and dip is from changing gear ...

OK,

I had som mail interchange with with Marko and we sorted it out as a rolling road dyno.
The dips you see are gearchanges.
Thanks Marko for sharing this fantastic work.

Post by **Piledriver** » Tue Jan 18, 2005 4:35 am

Yes, it was a rolling wheel dyno, so it was "first,second... THIIIIIRRRRRDDDDD!"

Dave_Darling · Post by **Dave_Darling** » Tue Jan 18, 2005 8:43 am

General, the simple answer is--

If you've got a ton of money to spend, and are good with tinkering and fabrication and want a project, then go EFI. You'll have great driveability and great power, once you get everything working correctly.

If you are budget-constrained, or don't want to be designing and building and tinkering for two years, slap a set of dual carbs on and call it done (except for the jetting).

--DD

raygreenwood · Post by **raygreenwood** » Tue Jan 18, 2005 1:56 pm

Jonas...thanks for the clarification! Thats exactly what I thought the burble may have been, cause thats kinda what it looked like at that rpm range...but did not know if this was a chassis dyno or not. Its still a steep slope though...and the engines volumetrics are definately made for HUGE rpm. Looks much better...now knowing what that burble is...but still hard for street driving. Ray

general_lee_jr · Post by **general_lee_jr** » Tue Jan 18, 2005 4:12 pm

I just got a responce from AJ Simms and I think I will go with the carbs. Fabrication is not my forte. Thanks for the info.

Post by **Piledriver** » Tue Jan 18, 2005 7:11 pm

AJ is a great fellow... and really does great work...
But Kadbombs will never idle right, and many folks who have had them on T4s have had fuel economy and other issues.

If you go carbs, try and get a new set of Webers from Redline et al.

Use search a bit...If possible, it might be down?

general_lee_jr · Post by **general_lee_jr** » Wed Jan 19, 2005 4:53 am

I really dont care about fuel economy because I will just drive it for fun. AJ's will do the works for me. It will be cool to have a set of kads as well as the joe cali conversion. I want it to look like a lame type 1 engine. I have had several sets in the past and i have never had trouble with the idle. The problem with webers is that everybody has them and it is a dead give away your engine might have some spunk. I think some 48mm kads will suit me fine. If they dont I will let you know and you can pull a told you so. LOL

Post by **Piledriver** » Wed Jan 19, 2005 9:16 am

THat's cool General, everyone loves a sleeper.

Just wanted to make you aware.

general_lee_jr · Post by **general_lee_jr** » Wed Jan 19, 2005 4:01 pm

Piledriver wrote:THat's cool General, everyone loves a sleeper.

Just wanted to make you aware.

I know man. Is the idle just with the type 4 as far as stock right out of the box?

Post by **Piledriver** » Wed Jan 19, 2005 8:42 pm

No, it probably gets worse with more cam...
And it effects the T1 the same.

It has to do with the firing order and engine/carb layout... 1432..

Problem might be apparent if we rephrase that 43 21
(also correct, just rotated the motor, right?)
4&3 get one carb, 2&1 get the other...

Each carb gets 2 sequential intake events followed by 2 dead time...
SO one cylinder runs richer/leaner on each side

This is a problem mostly at idle/low revs, Kad equipped cars frequently idle on 2. They can make good power/cost$$ though...

A big crossover pipe ala VWs PDSITs might help.

If I wanted stealth, I'd just make sure the hood closed and use a very quiet muffler, and a set of Mexi-chromies 5.5 with stock hubcaps.
Michelin Pilots 195-65/15 seem to work well in back, and 175/60s on front...

Non VW types still just see dual carbs, and actual VW gearhead types know that Kads can make good power...

greenacarina · Post by **greenacarina** » Fri Jan 21, 2005 11:32 pm

The crossover pipe will help smooth things out, but either way the Kadrons should idle just fine if they're tuned properly. AJ Sims will point you in the right direction. Good luck!!

Class 11 streeter · Post by **Class 11 streeter** » Sat Jan 22, 2005 12:13 am

I asked AJ some time ago about the crossover tube and how important it is. Based on his observations he feels that for a 1600 and smaller engines the tube made idle better by balancing out the manifold vacuum, but as an engine was built larger the crossover tube became ineffective and unnecessary.