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So... sled is a 1996 skidoo summit 670, I’ve swapped track to a 151” x 2” paddle, 700 pipe, bored carbs to 44mm, and it is already a hell of a handful lol I have the clutch set up so it bites right about the same time it comes on the pipe, so it has nothing, nothing, nothing, then 80mph lol but I have been collecting parts for about 2 years to turbo it. I’m thinking I’ll convert the bored out stock mikuni carbs to blow thru, adding a nipple to the tops, machining my own design adjustable boost referenced fpr, and running an electric inline fuel pump and an inline electric oil pump, putting a 2.5L tank under the turbo, but now some more thinking I need a bigger turbo. I can’t remember exactly what the one I currently have came off of but the turbine is only 35mm on the exit and 40mm closest to the center section, the impeller inducer is only 34mm... so it’s TINY. I also plan to add an EGT bung to the center of the expansion pipes and running a gauge so I can keep an eye on temps. Looking now at TD04 and td05 options though since my snail is a baby haha. Anyway, here’s pics of the snail tag if I can figure out how to upload. Anyway, now I gotta find some other project for this microscopic turbo... maybe a 440cc sled? I’ve got one Rotax 380 fan... haha

 

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Well just found my new slightly bigger turbo. It’s kinda a funky small twin scroll design off of a late model 2.3T ecoboost mustang. Here’s some pics, I just bought it, seller didn’t really know what he had. Here’s a couple pics. I’m betting the manifold has a kind of wastegate or electronic solenoid that controls which side gets flow. I recall seeing the new TD04 used by Honda on the RDX turbo that had a big flap built into the turbine housing and was operated by a wastegate, so once it has a few psi it increases the internal size of the turbine housing, allowing more exhaust to flow around the outside of the turbine, before the main internal wastegate would open and allow flow to completely bypass the turbine, I imagine this is similar but moved the primary wastegate or solenoid to the header/manifold. So I may try to keep that functionality if it’s not too hard, set up a second wastegate that opens the second scroll at a low boost level like 4-6 psi then the main wastegate at 8psi... if it’s too much work I’ll just die grind the web between the two down, and angle it so that the majority of flow is forced toward the tighter scroll... all just theoretical until it arrives.

 

Just my experience, but egt's are kinda worthless on these. I've personally burned down at 1100* and it's lived at 1300* both on race gas and 10 psi, probes at 4-5" from flange.

 

Well maybe that’ll save me a little work to skip that step. If no egt do you just check plugs often for proper color?

 

Plugs, and a wide band o2 in the turbo down pipe.

 

O2 on a 2 stroke? Does the burnt oil not foul out the o2 sensor frequently?

 

Mine were race only, but no failures in hundreds of passes on 3 different sleds. It's kinda a necessity if you don't enjoy replacing pistons.

 

I also ran strictly leaded race fuel, which everyone says will kill them. The AEM is my brand of choice.

 

I thought most of the late model oems were using EGT to run the EFI system but I’ll take your word for it and spend the money on o2 rather than egt. Thanks for that info!

 

The egt/pipe temp is usually for the ign curve. All my junk is either carb'd or 4 stroke, so I can't comment on the efi 2 strokes.

 

Yeah all my sleds are carb except for 1, and it’s one of the early Cat batteryless closed loop EFI sleds, but I have a few pieces and parts off of later Poo stuff. Anyway, I’ll hunt down a wideband o2 now.

 

Where are you located?

 

Idaho, near Boise

 

Nice. Good luck with the build, I'll be following.

 

MY NEW SNAIL!!! Soooo jacked! So which channel of the turbine do you think is supposed to be priority for reducing lag? Probably the smaller side? I think I’m gonna chop off the flange (and a large portion of housing) and weld on a v-band flange just to get rid of a sizable amount of excess weight, and just die grind the web at an angle to favor the one (smaller) side of the turbine housing. Anybody think that’s a bad idea? Why? I’m so stoked to be moving forward, I’ve got my custom machined 1:1 rising rate FPR done, just need to get some barbed to 1/8NPT fittings to attach the air pressure reference and fuel lines. Hopefully I can be hitting the mountains with it by mid-January.

 

To reduce lag, block off the inside half.

 

Inside as in whichever side is closer to the bearing housing/center section? I don’t really want to block it completely, as that will (in my mind) reduce top end flow, for my application I just want to port it with a knife edge bias toward whichever side helps it spool faster (the outer half?)

 

That's the trade off. Block it off to spool faster but lose top end or leave it open to keep top end power alive and slower spool time. I know some creative people have developd a switching valve for that. There was a thread or twon on here years ago about that. It was a Grand National IIRC.

 

right, I know that is the original intent of this turbo, but I’m not gonna do that, no blocking anything or flapper (as I’m sure the ecoboost mustang has on the manifold for this turbo) I’m just going to grind the web between them to try and get a tiny bit more percentage exhaust flow to go towards the fast spool side, until it has full exhaust flow/backpressure to force equal amounts of exhaust in spite of the offset ground ‘porting’

 

Ohhh I see what you're doing. I'm right there with ya now! I think it's a good idea.