Improving your IDA´s...

[NoBars]

What do you mean Darren?

[neil68]

Here's a comparison of my 44mm Raptor venturies compared to the typical/stock Weber vents:

[neil68]

Update:  Been driving for a couple weeks now, with the new Raptor IDA venturies (44 mm) and I'm very pleased with how smooth the engine is during street driving.  Since the snow has finally melted, I'm hoping to get on the drag strip next Friday to see if there is any effect on ET and top-end speed.  Hopefully get on the chassis dyno soon, as well.

[neil68]

Hate to burst your bubble but no Cobra enthusiast running 48idas will touch this "mod" that really isn't a mod at all. However, you should send them to various Weber specialists around the world and have them do the needed airspeed and airflow tests. From my emails that I am getting from people here, there isn't a whole lot of interest in this because they dont wish to compromise the original Weber design and modify the IDA body which is unstated here but would be necessary to model the 48ida operation after the car craft article about the demon carb. Facts are facts.

Just noticed on one of the GT40 forums that some of the Cobra crowd are now using the Raptor vents...

[neil68]

Well, the stock IDA stacks don't work well with Raptor vents, as they seem to vibrate...perhaps removing the stock auxiliary vent destabilizes the stock velocity stack (too loose).

So, I decided to install the Raptor stacks.  Very nice quality with a precision fit.  One interesting aspect, is that the Raptor stack has just a small lip that slides inside the IDA bore, and lines up with the main wall of the bore.  This should make for a smooth flow down to the venturi.

The Raptor stack is larger than the stock IDA stack at the top, so the dust covers needed to be modified.

I also picked up some 1.85 mm fuel jets to experiement as per Johannes jetting recommendations.

[JS]

Well, the stock IDA stacks don't work well with Raptor vents, as they seem to vibrate...perhaps removing the stock auxiliary vent destabilizes the stock velocity stack (too loose).

Spot on, Neil. The "ideal" is as you´ve found out also to run Raptor stacks. You gain 2-3cfm as well.

[henk]

i really curious to know about you ET with these raptor stacks and venturies.
i saw a youtube movie where the auxiliary vents where removed as well.
what is the exact purpose in fact for them?

henk!!!

[neil68]

Well, I went to Castrol Raceway (Leduc, Alberta, Canada) last night for the weekly Street Legal drag races.  I have been routinely obtaining ET's of approximately 12.8 seconds at this track, and only twice have I ever managed a 12.7 (once this year and another time two years ago, so very rare).

In my first race last night, the Beetle pulled off a 12.6174-second quarter mile at 109.04 MPH, and this was into a slight head wind.  The 60-ft time was 1.7710 seconds, one of my best ever.  My previous top speed was 106 MPH.

The track elevation is 730 m (2,400 ft) and the only other 12.6 ET I've ever achieved was at sea level (Mission Raceway, BC).  Could the Raptor venturies and the change from 180 to 185 main jets have resulted in a 1/10th of a second improvement on the ET?  Maybe.  They certainly didn't hurt

Here's an iPhone picture.  It's not crystal clear, but you can see how the stack blends into the top ledge of the bore, for a smooth transition:

[Torben Alstrup]

Sounds about right. "We" typically see ET reductions of 1 to 2 /10´s on the quarter once the carbs are dialed in.

T

[JS]

The top speed improvement sounds comparable to what others have gained also.

[neil68]

I went back and looked at my time slips and the improvement in ET was actually 0.16 seconds and top speed increase was 2.9 MPH (4.6 km/h).  Nice improvement

Now I've just got to remove some mass from the Beetle, as it's currently 925 KG (2,035 lb) with driver on board.  Might have to strip the interior a bit...

[JS]

Oh brother, here we go again. 

[Tobi/DFL]

Hi Johnny,

please explain...!

Tobi

[JS]

From JPM´s Facebook page:

"New product under developmet "Raptor Powerjet". A third fuel systemet for IDA carb.
Makes the power band wider with a lot more power in low to mid range and also a few ponies at top. Reduces the richness when throttle is opend suddenly at low rpm. Works very good with Raptor venturies and stacks👍. Pictures are just on prototypes for testing."

More pictures at his FB: https://www.facebook.com/pages/Johannes-Persson-Motorsport-AB/178561615658940

[Torben Alstrup]

That idea is stolen right out of the 48 Dellorto Trijet. But if he can make it work with IDA´s, so be it  

Looks like we will have something new to discuss on Dyno day.

I´m allready thinkin´, what if this can be used as a methanol injection (?)   

T

[LGK]

That idea is stolen right out of the 48 Dellorto Trijet. But if he can make it work with IDA´s, so be it  

Looks like we will have something new to discuss on Dyno day.

I´m allready thinkin´, what if this can be used as a methanol injection (?)  

T

Exactly what you said Thorben,this is also the modification that Doug Berg did on their 58 carbs,on Ron Flemmings superstreet engine they made close to 20Hp (if not more?) can't remember exactly what he told me, with all the mods Doug did on the carbs only  

Anyway hatts off to Johannes he's still doing more development,and everybody can take advantage of it,if they buy his products,those who don't...will continue to be slower  

[Torben Alstrup]

UHH! don`t put such thoughts in my head. I promissed myself that I would take a step down from all this. My mind is working overtime again 

T

[neil68]

Johannes has used Mikuni carbs on his other engines, and Mikuni pioneered the use of powerjet set ups in motorcycles:  http://classicmotorcycles.about.com/od/serviceandrepair/fl/Power-Jet-Carbs.htm

[modnrod]

..............Mikuni pioneered the use of powerjet set ups in motorcycles:  http://classicmotorcycles.about.com/od/serviceandrepair/fl/Power-Jet-Carbs.htm

Yes, I prefer the Keihin version personally.
 

But well done JPM for adapting it to a common auto application.

[neil68]

Oh brother, here we go again. 

So, I'm experimenting with the Raptor powerjet kit on my new 2332 cc.  I received some initial jetting recommendations from Johannes, such as reducing to 170 main jet and starting with 100 powerjet. Since I may not be able to get on the Dynojet for a while, I'm wondering what some of you ended up with for final jetting?

Lots of these powerjet kits have been sold, as mine is from the latest batch last month. However, other than a few instagram pictures, I haven't seen any feedback on jetting for the drag strip. Maybe there's some info on other message boards in different languages, if you can share with me.

Thank you!

[NoBars]

I'm interested to hear of progress on this as well.