Going to make the leap to ITBs...
 

Finally the winter projects are coming into view... ITBs. :D

I've decided on a kit from Al at X-Faktory X-Faktory - Home with Megasquirt EFI and EDIS ignition (no more dizzy.) Al can offer any ITBs I like with his kits in any combination. I'm down to the following:

1) go with a full kit from Al with his Triumph speed triple ITBs on a custom manifold. The manifold is not a straight shot for the outside cylinders (like webers or PMO) but this is by far the more affordable ITB option. I doubt the staggered manifold will really matter for a street driven car. Or?

2) Full kit but with Jenvey ITBs. Straight shot to all cylinders. A good chunk more expensive then the Triumph ITBs.

3) Same but with PMO ITBs which are again not a straight shot. Same price as Jenveys. My least favorite of the three but the best option as far as air filters and rain hats are concerned, and where I live it rains. A lot.


Should I just save the cash and go Triumph? There is a budget to adhere to on this, like all things in life. Thoughts welcome.

Dumb question: Why are straight tubes costlier than bent tubes?

I'm just here for the photos...

I can't wait to see the finished product.

I think the bent tubes allow use of the cheaper triumph TBs, which have spacing optimized for the motorcycle they came from.

With an internally stock 81SC based on your signature you will not be able to tell a difference in performance between the options you posted.

They will all give you superior performance compared to the stock CIS.

Depending on variables it might be worthwhile to consider the new shafltess butterfly ITBs. Here https://www.atpower.com/ and here: https://renorennsport.com/products/

I believe that they make more power than most or all ITB set ups that do not have a shaftless design.

Something relatively new to consider.

Oh, I've seen them, but $4K just for the ITBs, and that is with the 10% discount they have at the moment. Unfortunately out of my budget, but they are beautiful!

Thanks Jamie. Yes, stock 3.0. I should have mentioned that my plan includes building a better 3.0 in a couple years, or perhaps a 3.2SS. Either way with happier cams. Al says that the 42mm ITBs will be just fine for the larger motor when I eventually get there.

But for now the ITBs are to get some more fun out of the stock engine.

I'd say if you're going through all the effort you should use a more modern efi setup. I cant tell, but it looks like an ms2 ecu? I know rasant sells an ITB efi setup that's full sequential fuel and coil on plug ignition.

Porsche 911 Engine Management EFI Kit- 2.7/3.0/3.2L With ITB's - Rasant Products

IMO biggest disadvantage of Rasant kit is that the triggering system is based on distributor. chains still have some slop and crank firing system is by far the best.

Isn't the distributor run off the spiral gear on the crankshaft? No chains. Just a worm gear.

Pretty accurate, but the bushings in the distributor do wear with a lot of time. Seems like a very reasonable thing to use for a conversion.

Oh, yeah, my mistake. It is indeed pretty accurate then and easy to use as one can install it easily unlike crank trigger.

Distributor pickups are not as accurate. They work well. However, There is 1-2 deg of timing variation just due to the overall backlash tolerance of the worm-gear mesh. Its usually not enough to be a real problem unless you are pushing the BMEP limits. In other words, you can tune around it.

PMO's and Rasant is by far the cleanest and most modern.

If one already converts to EFI (or has 3.2, 964 or 993) then I can offer VEMS PnP which plugs into factory DME connector (works with stock sensors, no need for AFM though) and is at least as modern as AEM. Comes with well-running tune and full support. 1250 euros shipped, includes built in dual wideband (one sensor included), EGT (up to 6x) etc-etc.
Check here www.facebook.com/vemsporsche

I've got a long answer below but my short answer is go for the triumph kit from Al.

THere are however lots of options out there. I started my ITB project in May 2016. I didn't have it running until a year later. I handful of broken head studs caused some delays. Nonetheless, here is my shopping list and cost breakdown. I'd recommend getting more of this stuff as a kit from Rasant or Closed Course Motorsports or X-faktory. It would be worth spending the little bit more to not have to hunt for all of these parts separately. Plus you know that you are getting the right sensors etc. I had to purchase a couple things twice because what i got i couldn't find calibration specs for in all cases. Its just easier and quicker to let those companies do that part for you.

The bulk of the ITB project bits are outlined below:
$225 Triumph ITBs (2 racks used on eBay)
$1550 AEM Infinity 506 + flying lead harness (price has come down some if you search)
$499 Closed Course Motorsports manifolds
$220 AEM EPM (for cam and crank position)
$199 EPM adaptor from Rasant
$25 eBay vacuum manifold
$75 3.2L cyl head temp sending unit
$110 Tomei FPR
$25 GM air intake temp sensor(amazon)
$225 Close Course Motorsports throttle linkage kit
$140 6 audi smart coils (Advnce Auto Parts)
$30 audi coil plugs/connectors
$65 Wideband O2 sensor (Advance Auto Parts)
$40 GM 1 bar map sensor (amazon)
$20 0-100psi fuel press sensor
$20 knock sensor (eBay)
$150 random connectors and pins and some wire and wrap
$60 good crimper for molex and Junior Power Timer pins
$100 fuel line, filter, fittings, crimp clamps

There might be some stuff I'm forgetting but that's about $3800. I bought an IACV but ended up not using it. Might have to add it when temps drop but for now its starts and idles just fine without. I could probably benefit from a few more sensors ie engine oil temp, pressure but this wouldn't add too much to the price.

My motor is mostly stock as well. I have some upgraded studs and a 2.7L crank but otherwise small port SC stuff.
The benefits as I see them are:
1. The education you get doing something this serious is almost priceless. My confidence grew leaps and bounds and I crave more and more now. knowing how this stuff works is truly a gift that you can only get going thru a project like this. One of my favorite experiences right behind loosing my virginity and falling in love! (two separate things/experiences!)
2. This setup seems very reliable so far. And when something does go wrong, its much easier to find the issue when everything is talking via a laptop to you. Using the Infinity Tuner software provides everything you need to troubleshoot (once you understand it all)
3. Power increase - I haven't dynoed yet but even with my street tuning it feels much stronger than w/ CIS
4. Noises. what a sound!
5. Looks so business and way easier to work on with nothing blocking your access. Valve adjustments are way faster for example. Getting to the triangle of death and oil leaks as simple as popping the hood and reaching to the back of the motor.

so lots of ways to get where you are headed. I took the very long way to save where i could. I did splurge on the Infinity but its so worth it. Its capabilities around traction control and e85 and TBW mean you won't have to upgrade in the future. That might be the only thing I strongly suggest to you to change from you plan. Go with the AEM.

Thanks for all the input everyone!

I would really love to go for the Rasant kit (AEM), and have talked with Andrew a bit about it. As mentioned above I'm looking at a complete package from Al as he can provide a very complete kit configured any way I choose, and support to boot. That kit can be any combo of MS or AEM, and any of the common ITB options. The real question was if I should consider fancier ITBs, or if I'll get the same joy from the Triumph units anyway, at a much lower cost.

Unfortunately as we step up to the higher end packages with AEM the price goes beyond what I want to put into this now and still doesn't get me Jenvey or PMO ITBs. Triumph Speed Triples and Al's setup with MS2 (with crank trigger and EDIS though) are rather more affordable. Al can also provide full sequential and COP's with MS3 or AEM, but again I have to consider that this is a hobby car for the street. I'm looking for throttle response, sound, and a bit more power, with a system that I can transfer over to a new build in the future with better cams and flow-- without compromising or having to start over. Perhaps I'm being short sighted but I can't argue with Al's pricing, and his willingness to answer my noob questions is second to none!

So, lots of input on choice of EFI, and some on which ITBs which was the actual debate...SmileWavy

I would go with the triumph itbs, cost vs benefit doesn't seem to be worth it for the benefits on the jenveys.

Is his ms2 setup sequential for fuel? You give up a lot of that throttle response youre looking for if its batch fire. If al can do ms3x with that kit, you should definitely consider it. The ecu is only a couple hundred more and is a major improvement.

Sent from my SM-G950U using Tapatalk

following this. ITBs may be my next step. Curious about the comment on sequential fuelling vs batch and throttle response. Why would there be a significant difference ?

I did the Triumph and Rasant (AEM) route. I have a 3.2 and replaced a perfect good Motronic system. However, it looks fabulous, is a great conversation starter at car shows (I have two speed triple intakes in my car), sounds great, has been a blast to tinker with and tune, and has changed my car's performance characteristics in a way that I like better (note, I would not say the performance is better at this point, but I like the quicker throttle response and the power is slightly higher in the RPM range).