Improving your IDA´s...

[Jim Ratto]

i have a set of the 42mm jpm vents and the jpm stacks going on a 2276 ida motor when its finished. looking forward to what its going to be like does anyone know if they will help all round driving on the street???

cheers andy

With regards using them on the street, please take a look at the curve again and pay attention to the range from 2500 rpms up to 3500 rpms. This is the area where you cruise and where many experience issues (dead spot/hesitation) With the JPM parts you gain almost 20hp in this area (from approx 62-63hp to almost 80hp). You are looking at a improvement of around 30% in the most critical range for street driving.

-BB-

Now I'm really interested... this is where a lot of compromise is made running the 48IDA on the street.

[NoBars]

44s

I went with Johannes reccomendations. I'm drinking the cool aid. He recommended the 51s too, and they will probably be coming this winter.

These vents will work with either. It's not like regular 51s where you need to buy a bigger OD venturi to keep the vent in place because when the throttle plate area is opened up the standard vent would fall into the throttle blades. But if it is already opened it will work fine because they hang off the aux vent registers. The bore above the venturi that the stack normally fits in is now the carb throat, making a bigger variation  in bore size to the choke which I am guessing is what creates enough signal to suck the fuel out of the bowls.

They are really very clever. I'm glad I got the stacks too. It all makes perfect sense. They just look like airflow...although I am not sure Bernoulli's principle works the same here as it does in Europe. At least I am closer than Southern California.

After the October ASA race I may send them to Joe to play with if he wants.

[Jon]

They just look like airflow...although I am not sure Bernoulli's principle works the same here as it does in Europe. At least I am closer than Southern California.

 

[NoBars]

Zeroing in on the setup. Initial impressions driving around is that with about 4 stops for various jet changes is that it already drives as good as my old setup. I did one belt off pull from 4k to 8200 in 3rd and after the rich spot from the accelerator pump cleared out it held 12.7 afr until I let out.

Track time Friday night.

So far I am "well chuffed"

[wolfswest]

Zeroing in on the setup. Initial impressions driving around is that with about 4 stops for various jet changes is that it already drives as good as my old setup. I did one belt off pull from 4k to 8200 in 3rd and after the rich spot from the accelerator pump cleared out it held 12.7 afr until I let out.

Track time Friday night.

So far I am "well chuffed"

Anthony,

I saw you went with the 44's, were your "normal" venturis also 44's or smaller?

[NoBars]

42

[wolfswest]

42

so you gained top end power and the car remains streetable, even at lower rpm's?

what are your engine specs?

[NoBars]

Ass dyno says yes, I picked up power. I will find out at the track Saturday. Never been on a dyno.
2387, big stock style heads, big cam. Lotsa compression. Race gas, marginal street car, mid 11s.

[Old Guy]

Good luck Anthony.  We'll be real interested in what your times at the track are. 

[wolfswest]

Ass dyno says yes, I picked up power. I will find out at the track Saturday. Never been on a dyno.
2387, big stock style heads, big cam. Lotsa compression. Race gas, marginal street car, mid 11s.

 

[Eivind]

here's a clip the JPM Dyno Day #10

<a href="http://www.youtube.com/v/kTDR7Use9vU" target="_blank">http://www.youtube.com/v/kTDR7Use9vU</a>

VW T1 1302L 1972

2332ccm
210 PS @ 6410 rpm
252.3 Nm @ 4700rpm


JPM MS230 Cylinder Heads: Alloy 356, T6 kvalitet 48x38mm Manley Typ 4 ventiler.
JPM Rocker 1.45
JPM 00408 Raptor kam (282° 10,70mm)
Weber 48 IDA, JPM Raptor venturies og Raptor stacks
Bosch 010 Distributor
Bosch Blue coil
CSP Python 45mm exhaust

[Chris bugster]

Well done. I remember when I started racing about 22 years ago that this kind of power was only found on full on drag engines. How times have changed.

[JS]

Indeed, making this kind of reliable power while retaining heater boxes and fan belt is truly amazing! 

[drgouk]

Ass dyno says yes, I picked up power. I will find out at the track Saturday. Never been on a dyno.
2387, big stock style heads, big cam. Lotsa compression. Race gas, marginal street car, mid 11s.

Hi Anthony,
                How did these perform at the track?

Thanks

David Gouk

[NoBars]

I only went once. My tuning was off. I plan to put it on a dyno as per Johannes recommendations and  get the A/F right before my next outing.  I would have gone again but I broke the pinion bearing (my builder says it is the only one he has seen break) in my trans, eating the case and R&P.

I still went a personal best, but the MPH was down. It was way fat. I was relying too much on the A/F gauge. If I had just pulled a plug out...

I'm chopping away right now trying to get another 50 pounds out of it without it looking like a race car.  

[neil68]

here's a clip the JPM Dyno Day #10


VW T1 1302L 1972

2332ccm
210 PS @ 6410 rpm
252.3 Nm @ 4700rpm


JPM MS230 Cylinder Heads: Alloy 356, T6 kvalitet 48x38mm Manley Typ 4 ventiler.
JPM Rocker 1.45
JPM 00408 Raptor kam (282° 10,70mm)
Weber 48 IDA, JPM Raptor venturies og Raptor stacks
Bosch 010 Distributor
Bosch Blue coil
CSP Python 45mm exhaust

Eivind:  May I ask what CR is your engine?  Also, did you test the Raptor venturies/stacks versus the stock IDA stacks?

The reason I'm asking, is that I have a similar engine in my '68 Beetle:  2332 cc, 10:1 CR, JPM MS230 heads, 1.4 rocker, JPM 06908 Raptor cam (274° 10.8 mm) and am always interested in tuning this combination further.  Thanks!

[Lids]

this might help getting the floats correct: http://www.thesamba.com/vw/classifieds/detail.php?id=1570935

[Jim Ratto]

Did anybody ever answer Bruce's question about needing to change emulsion tubes to get best gains from the venturi/nozzle mod? Just curious. From what I have been learning and playing with, using the wrong tube can really chip away at how the car responds.
Or are these working best with typical F7 / F2 choice?

[magic]

I used F20 tubes with my 44mm Raptor venturies
There are some jetting recommendations on JPMs website
http://jpmotorsports.se/ms/ms/j-p-motorsport-ab-produkter-helsingborg-254-68/ms-90000825-p-4/#Raptor Venturies

Happy New Year to all of you 

[JS]

Car is in the workshop, but I believe I´m also using the F20´s.

[NoBars]

F 20s here as well.

[neil68]

I used F20 tubes with my 44mm Raptor venturies
There are some jetting recommendations on JPMs website
http://jpmotorsports.se/ms/ms/j-p-motorsport-ab-produkter-helsingborg-254-68/ms-90000825-p-4/#Raptor Venturies

Happy New Year to all of you 

Since I've got F2's already installed (one of JPM's recommendations according to your link), I'm going to start there first with the 44 mm Raptor venturies.

I hope to get the Beetle on the chassis dyno in a few weeks, but we're buried in snow at the moment

[NoBars]

Ooooooo, Neil is drinking the kool aid too!
Your carbs are still 48 mm butterfly, correct?

[neil68]

Ooooooo, Neil is drinking the kool aid too!
Your carbs are still 48 mm butterfly, correct?

Yeah, I guess I'm just copying you Anthony...first I buy your wheels and now the Raptor vents

With the JPM  MS230 heads and Raptor cam kit, I'm sort of gradually building a Swedish engine.

Yes, my carbs are the original Italian 48 IDA's, except with third progression hole and enlarged float bowls by Jaycee.  However, I might try to experiment and test a bit with different stacks and the Raptor venturies...I prefer to make one change at a time, and then check the results:

1.  Original Weber IDA stacks that fit "inside" the carbs;
2.  Geers stacks that have the full-size opening and fit "on top" of the carbs.

With the auxiliary vents removed, I'm curious as to how the two types of stacks will perform.  I may try Raptor stacks in the future, when budget limitations have eased.

[Taylor]

Hey Neil, not that my combo is the same as yours but switching from stock IDA stacks to jaycee stacks cost me 3 peak and 2 average hp on Roger Crawford's dyno.  Motor is 2210 ccs and made 227 hp.

[neil68]

Hey Neil, not that my combo is the same as yours but switching from stock IDA stacks to jaycee stacks cost me 3 peak and 2 average hp on Roger Crawford's dyno.  Motor is 2210 ccs and made 227 hp.

Thanks for the information.  My Geers stacks are somewhat similar to the Jaycee, from what I've seen, but there have been a few varieties produced:

[NoBars]

The jpms have a real similar profile to stock, just bigger.

[BeetleBug]

There is a lot of really interesting information out there with regards to intake bellmouths. I recommend that you you google: "Prof. Gordon P. Blair intake trumpets" and download the pdf. Poor a cup of tea and enjoy the read before you remove the Jay Cee style stack covers and throw them in the garbage.

-BB-

[JS]

I know that JPM tested several designs both on the flow bench and on the 1-cyl R&D dyno before going into production. As "Prof. P. Blair" states in his article the advances are not massive, typically 1-2hp compared to an original IDA stack.
I cannot help myself thinking there´s a reason modern Formula-1 engines use stacks with a "simple radius design", not massively "V" shaped like some VW suppliers sell. 

[K-Roc]

There is a lot of really interesting information out there with regards to intake bellmouths. I recommend that you you google: "Prof. Gordon P. Blair intake trumpets" and download the pdf. Poor a cup of tea and enjoy the read before you remove the Jay Cee style stack covers and throw them in the garbage.

-BB-

What's wrong with blocking off air to the air corrector jets ?