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Went back to the summit again this morning to test a couple of settings. I mentioned the barometric pressure table under Settings, earlier. I've now got that table roughed in from sea level up to 10,000 ft (100 kPa to 69 kPa). I only tried to get the same idle AFR (13.8) at each of the 5 spots I stopped at, so who knows about the rest of the VR map.  I'm happy to share the numbers with anyone who is interested.

@DannyP and @Stan Galat, the other settings I found that seems to make a huge improvement for altitude changes are the two checkboxes at the bottom of the VE map screen. The first (Multiply VE value by MAP:Baro Ratio) is usually recommended to be on. The second one (Multiply VE value by AFR to AFR Target Ratio), is not as frequently recommended, but I found that it did some pretty good on the fly adjustments to compensate for the altitude changes. I suspect I'll normal keep it turned off, but turn it on when I'm heading up country.

Glamour shot with the telescopes in the background



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ITB sizing - The crazy scheme continues to work very well. I'm now doing the background reading I should have done before jumping in with both feet. I found a good thread over on shoptalkforums by Paul, the guy who makes the throttle bodies at VW Speedshop. Although the thread is about IDAs, he states that individual throttle body butterflies on VW engines only have to be 42mm to exceed 200hp. I ball parked mine based on what I used on a supercharged Miata a while back, and bought 45mm ITBs.  I doubt I'll be breaking 200 hp anytime soon, but I'll be ready. The downside is the throttle can be a little twitchy since you're opening/closing a lot of venturi space with small changes in the pedal. It isn't annoying or something I feel a need to change, but the thread recommends 34mm-36mm ITBs for most VW applications to get a more linear throttle response.  Consider this as you are sizing the ITBs for your application. Here's the link:


It's true, TRP. You'll need a degree in stripping, twisting, and taping wires from Cob-job University though. You're not color-blind are you? LOL!

Mike, I've got 48mm CB throttle bodies, so I'm guessing my throttle may be jumpy.

I have read that slightly smaller throttle bodies can be used because there is no venturi inside. That makes sense to me. 44 Webers have 36 vents. I'd bet 40mm ITBs would be perfect for my 172 hp 2165. 

I'm going to use what I have though, they bolt right up to my manifolds. The bottom of my Webers are smaller than the opening in the manifolds, the ITBs will match, even with the injectors.

Last edited by DannyP
@Stan Galat posted:

@Michael Pickett-- ITB sizing is a rabbit hole I'm interested in going down. I know there are charts someplace-- do you have any links?

This is the link that made the most sense to me:

I would also recommend calling Paul H at VW Speed Shop or PMing him on ShopTalkForums. He's been very responsive to my questions.


Last edited by Michael Pickett

@Sacto Mitch, I just posted a short video the day I started it up. I'll get some video of it actually running so you can hear what it sounds like. Short answer, it feels a lot more powerful and responsive and sounds good, too. It's very subjective data, but I have to say that it has put a lot of grins on my face since I've got it tuned. 

From the non-subjective point of view, you 3 main tables that control the spark, fuel injected, and the air:fuel ratio targets. Each table has 256 cells (16x16) that get filled with what you want to happen at various RPMs and engine loads. That is an amazing amount of precision compared to our old carbs and distributors, even if you have a ton of springs and carb jets.

Here are my current tables shown in TunerStudio:

Timing Table

Screen Shot 2020-08-08 at 4.30.35 PM

Fuel Table

Screen Shot 2020-08-08 at 4.30.07 PM

Air:Fuel Target Table

Screen Shot 2020-08-08 at 4.30.51 PM

I suspect most of the power and responsiveness feeling comes from having better control of timing and mixture levels. Anyway, that's a non-dyno observation so take it for what it's worth. 

I'll see if I can get Marianne to do a video while I go by and will try to get a slow run, too.



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Thanks for all the feedback, Mike.

I was thinking more of a video of the car at rest, just running the engine up slowly through the rev range.

With carbs and a normal distributor, once you get used to the sounds of a particular engine, there are places on the rev range where it just sounds 'happier' (for want of a better term). For example, my engine sounds more relaxed at 2800 than, say, 3200.

Now that the bots have had some time to dial in your engine, I was wondering how it sounded and if it sounded noticeably different from an engine with carbs and conventional spark. (My engine did get a lot better when I upgraded to a distributor with much less spark scatter.)

Thanks again.

@DannyP posted:

@Stan Galat : Order the 45mm. They will work, and very well, with anything from a 2110 to a 2332. 

That would be the default, but In think maybe the 40s or 42s are what I want. There is no venturi, and throttle response is way more important than not in this engine.

I asked because I love the math of it all. I've already written the TB guy (Paul) to get his opinion.

Last edited by Stan Galat


Thanks, Mike. I hope others will benefit from these, too.

As I suspected, it sounds really smooove.

One telltale I listen for when dialing in the carbs is the sound just off idle - when the throttles are just starting to open. If it's out of synch at all, you will hear it there. Yours is dead smooth, side to side.

And it sounds really strong accelerating under load, too.

One sound I think is common to all of these engines, though - that faint 'too fast' when you're into it just right.


Last edited by Sacto Mitch
@Sacto Mitch posted:

One sound I think is common to all of these engines, though - that faint 'too fast' when you're into it just right.

Haha! There's an early clip in my build thread where she's videoing me doing a first engine start in the bare chassis. As I backed it out into the street you can hear her saying "Don't do it. Don't do it." She knows me pretty well...

Last edited by Michael Pickett

Mike, I absolutely love it! Sounds great. It certainly sounds like more than a stock or near-stock motor.

What is your idle speed, kinda on the high side, or is that for the A/C?

Stan, what venturis do you have in your Dells? That's probably a good starting point, a little larger than that, like 40 or 42. You're running 38 vents, correct?

Last edited by DannyP
@DannyP posted:


Stan, what venturis do you have in your Dells? That's probably a good starting point, a little larger than that, like 40 or 42. You're running 38 vents, correct?

As you know, the 45s come with 38 mm vents-- and that's what I was running with the 2276 (as you suspected). I'm hoping the new engine will be in the same HP range, so I'd suspect that 38s or 40s would be just about right... but I'd like a chart (because I'm me). The Panchitos smaller intake valve makes me leery of getting too big, and a 36 mm TB will support up to 170 hp (according to the guy who makes them). I'd almost bet a 38 mm TB would be perfect, and give me nice throttle response.

You are aware, I'm sure, that 48s come with 40 mm vents. I'd suspect that your 48 TBs could support 350 hp.

Mike, I really like about 900 rpm warm, it ends up at 700 or so ice-cold, which won't last long in your climate. That's very cool about the A/C compressor switch. Smart choice. I think you could do some idle timing magic in the warmup/cold start area of Tunerstudio. That's what I'm looking at doing, and if it doesn't work it isn't all that difficult to add IAC stepper, 4 wires and some vacuum gymnastics.

Stan, go with the 40s, just in case you ever build a 2332 or 2387.

I think you're right, @DannyP-- I talked with Paul in the UK this AM. He recommended the 40s, which he says will support up to 200 hp (on his shop dyno, not a butt-dyno). I checked various charts and think this is probably the direction I'm going. As far as injectors, I think something in the 30 lb/hr range seems about right (they will also support about 200 hp). 24 lbs/hr would probably work, but might be tight.

As always, I'm very new to this and appreciate any comments. @Michael Pickett-- as the "old pro" at this, what do you think? There are low impedance, high impedance, short, tall, and various styles of connectors (who knew the connectors might be the hard part about this?). I'd like to take this one step at a time-- I've got the trigger wheel and sensor, I'd like to get the TBs, fuel pump, and regulator before long.

Stan: Injectors: You want "high impedance" injectors, up to two of those per Speeduino channel without using series resistors like you have to with "low impedance" injectors. I'm not sure what your Megasquirt ECU requires. In a Speedster engine bay you want the shortest injectors you can find for air cleaner and sidewall clearance.

I'm looking at 37 lb./hr from CB Perf., the closest I can get to the 34 pound "low impedance" injectors I already have. I can't live with adding resistance to the existing injectors to make them work. The 37 lbs. have 3 holes for good spray pattern and hopefully good atomization.

Lots of good questions answered here:

Last edited by DannyP

@Stan Galat, I just broke my favorite espresso cup after sleeping for 9 hrs (7+is my usual). I've got a double shot in me now, but I may have to add thoughts later as my frontal lobes kick in.  

If you are going with Paul's gear, get the short injectors to give more side clearance. I've always chosen high impedance because they work right out of the box with the ECUs I've been using. You can make low impedance injectors work with additional circuitry, but it didn't seem worth it (and I've never been disappointed).

I'd trust Paul's recommendation for the 40s. He knows his stuff and has the data to back him up.

On injector size, I'm sure you've read the entire internet on the topic, but the rule of thumb is to size them so at full engine load/output, you're running an 80-85% duty cycle. If you oversize them too much, they spray very short cycles and aren't as precise. On mine, since I was doing a budget conversion, I got a 1/2 price deal on the 17lb accels. That's right at my top range and I worried I'd over run them. Since 99% of injectors are flow rated at 43-45 PSI, I pushed the regulator pressure up to 60 PSI to give me room at the top. No problems.

Injector connectors, more on this after I finish my second double shot and walk some dogs that want to go sniff the world.

Fuel Pressure:

@DannyP, sounds just right. One other thing, you mentioned that you are putting the fuel regulator in the engine bay. That is good. I have my regulator up front and found that the various hoses and connectors lowered the actual pressure in the fuel rails quite a bit. Measuring your actual pressure in the fuel rails is a smart move. As Danny states 43.5PSI is your target unless you want more fuel than the injector specs.

I picked up this gauge adapter for around $14 on ebay along with some 6AN caps:

Y32 -6AN Female To -6AN Male W/ 1/8 NPT Side Port For Gauge Sensor BLACK Coupler

Injector connectors: In general, find the injectors you like and then buy connectors to fit.

All of the injectors I've used (miata, porsche turbo, this project) were full size and used the old style EV1/Jetronic/Minitimer connector. I looked up the Accel injectors I bought to make sure they were the same. I paid around $20 shipped for 4 pigtail connectors from ebay. Here are the keywords to get the item I bought: Set of 4 Fuel Injector Pigtails fit Bosch EV1 Jetronic GM FORD DODGE [EV1F-4]

Set of EV1/Jetronic/Minitimer connectors 

ev-1 connectors

You can probably find them cheaper and you can also find the un-built connectors that you will need to crimp. I can crimp, I just don't like to (especially with waterproof connectors). If you've got GOOD crimping tools and some experience, do what you like. If not, save yourself some headaches and buy pigtails. Wrap, solder and heat shrink will give you more reliable connections if you are are low on experience and don't already have good crimping tools.

EV6/EV14/USCAR connectors (from


The EV6 fuel injectors replaced the EV1 in the next line of fuel injector evolution. The EV6 injector is nearly identical in height but the body of the fuel injector is narrower or “skinnier” when compared against the EV1 injector. ... The EV14 injector is medium length - shorter than the EV1 and EV6 injectors and features a slim style body.

Multec 2 / Mini Delphi connectors

multec 2

Denso/Sumitomo connectors - used widely on Japanese cars



Some examples of injectors and connectors - adapters are available:



Footnote: stay away from diesel injectors - they don't have the spray pattern you want.



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@Stan Galat@DannyP mentioned above that you might be using a Megasquirt ECU. Just curious if you're heading in that direction. I ran the MS II in the old turbo for years. As I'm sure you know, it has a few more features enabled than the Speeduino and is an excellent, reliable box (I bought a spare and never used it in 10 years of driving). 

Tunerstudio and Megalogviewer are the same software interfaces for both. The firmware loaded into the ECU determines the menus and features enabled in Tunerstudio. The forum support for Megasquirt is massive while Speeduino is catching up. Many questions I had about setting up Speeduino were answered by searching the Megasquirt forums. Firmware updates on Megasquirt II are less frequent than updates on Speeduino. Speedy is VERY open source and the main developer of the hardware and software has been holding online classes on how everything works and how you can change it if you want to (preserved on Youtube). Those are the main differences. I'm comfy with Speeduino as a lower cost solution, but the Megasquirt boards are extremely capable and mature.

@Stan Galat, Injector sizing doesn't have to be absolutely precise. An example: the Bosch 0280158191 30lb/330cc injectors I noted above came stock in the 2016 Ford Transit 250 with the 3.7L 270hp V6. Running the engine specs back through an injector calculator suggests they normally run at a 65% duty cycle. Plenty of top end and the manufacturer felt they could meet drivability and emissions standards with a 65% duty cycle. It doesn't have to be right on the money.

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