Putting a turbo on the ol' 1915

[GARRICK.CLARK1]

Believe it or not mine are 36mm.
So originally had 32 mod rings/34 vents. Went bigger on the vents as an experiment/ nothing happened to drivability so left it as is. I'm gunna go to 37mm vents now that the mod rings are 34mm
I Enlarged the carb vents to give the float bowl a good boost signal. Some people use vent tubes, forget that, not needed if the vent it big. I can see the float bowl and float clear as day through the big vent hole
So small mod rings = small main jet
Bigger mod rings = bigger mains.
No mod rings = it wont work

[John S.]

I love seeing all the tests and results posted. I hope it all helps me for my single blow through. When I finally get to it.

[Therealkoop]

Garrick is that on a 40idf or is it something larger?

The mod rings work so well, how do people get extra fueling during boost on a drawthrough setup?

Im trying to make info on this thread complete as possible, I followed A LOT of dead end threads trying to figure out my build.

[GARRICK.CLARK1]

Mine are 40 dells. Similar to weber's in some respects, they use mod rings/work the same way.
Thing with small mod rings is the enrichment is too strong. I was in the 10's on the AFR gauge as the boost started.
I enlarged the mod ring size a mm at a time and it weakened the signal to a point were the 10 was then at wide open throttle. By the way 10 isn't the number to look for at WOT, its more like 11.5 -maybe 12.

I did try draw through ,its easier to set up but has its own problems, hence why I'm back to blow through.

[madmike]

Draw threw enrichment on Boost is done with Boost referencing the power valve on a four barrel carb and the secondary circuit ,or Boost ref the fuel reg on a SideDraft carb I've done both and the 4 barrel works best for my app. heck they works so well I'm installing one on my sandrail

[Therealkoop]

Yeah I was surprised at how much my mod rings enriched, but it dialed in easy after they were installed.

Boost referenced power valve, makes perfect sense. I knew yall had to be doing something after seeing how well the mod rings work.

[madmike]

when i had the 750 demon carb on the 2276cc without the mod it still worked

[Therealkoop]

Its actually getting pretty nice out. Been cruising around, getting more data and building confidence. Seems to be running amazing. Better power, great idle, ect.

Thought I popped the trans or motor today taking off from a light. Somehow my throttle linkage fell off (the center bar). I thought "Welp, that was fun for a minute". Put some blue loc-tite on the bolts to help prevent vibrating out again.

Only "problem" im seeing now is that while cruising in 3rd or 4th at 55-60 MPH (and faster im sure), the turbo is producing 1-2PSI and causing AFR to run rich. Im not super concerned about it, but it might be some improvements that can be made.

[John S.]

Downshift, lol!

[buguy]

Your making boost on cruise?

[Therealkoop]

Yes, its just off the 0 on my boost gauge but its enough to cause the mod plates to start having an effect and drop the AFR. My cruise would be 3-3500 in third gear, or 2500ish in 4th gear. With my gear ratios and tires that is right around 60mph.

It is a very small turbo, and a regular old school wastegate.

[buguy]

I'd be worried about that building heat.

[Therealkoop]

Still running well. It makes more power especially mid range, but top end falls off a bit (Spark limited at 5800rpm max). Now that its running stable I want to check out a few things.

Right now the fuel pressure reference and boost gauge are coming from the charge pipe, pre-mod plate, pre-carb. Has anyone tried reading values from both above and below the carbs? Was there any notable difference? Right now Im reading about 10psi, im going use one of my 4 vacuum ports I made prior to see if there is any notable difference between the two. I also want to see if it behaves any differently when at cruise due to my low boost at cruise problem.

Im also going to tap into the collector before the up pipe, and before the turbo to read the exhaust pressure relation vs the boost value. I think the turbo flange itself is the largest restriction in the system, not much I could do there but im curious what relation ill see.

Thinking of rigging up some kind of thermocouple to read air temp. No intercooler and no water/meth means im sticking to 10psi max for now, but I wouldnt mind getting some data and seeing if I could push the boost up a bit with some modifications.

[madmike]

pushing the boost up ,, new the 5-7 lbs wouldn't last ,

[Therealkoop]

Hahaha, probably already pushing the limits with no cooling!