YD25 Compound Turbo

set both turbos at stock waste gate setting and go from there will be the way to go

Well been a few days since I have posted. Turbo is all bolted up and running, took it for a smash around the block this morning and man does it hall arse! Can easily get 30psi in 3rd and 4th without using full gas. Here are some more pics

Turbo bolted up, oil drain and feed are attached


Working out the intake 3" to 2.5" reducer and a 2.5" 45 degree bend. Went back to 2.5" intake piping to keep the MAF sensor happy

Dump pipe bolted up


Didn't quiet meet up with the original 3" system so Ill get that sorted this week, the shop can sort that one out


Final product




A/C into the cabin is disconnected as its in the way. Not to sure if Ill get it plumbed up, do I really need it in a race car?

Egt sensor is right off the back of the secondary turbo but It is reading low as the gases have been through 2 turbos. Going to move it to pre (primary) turbo. Still need to run a second boost gauge and manual boost controller for the secondary turbo.

Once these things are sorted it will be going into the shop for a Unichip and safe tune. Going to target 30psi on full noise and 19:1 AFR's

i forgot they are maf only.
you really need the 3" pipe. find a different maf ? or rewritten ecu?

nice pipe fitting and welding
its looking good.
edit: looks like air temp probe in there as well. that will be interesting to see.

looking good! that cutting and welding job youv'e done is magnificent! What type of racing are you setting it up for?

Very nice mate!!

**** yeah nice man!

I wont lie, I didn't weld the stainless tube, one of my mates did...........
I just ordered a weld in MAF sensor flange from the states, the postage cost more than the fitting! 2 - 3 weeks away for that one
That air sensor will be slightly moved so its not resting on the hot exhaust pipe.
Going to run another Egt sensor after the primary turbo, there is already a bung welded in the pipe for it.

Racing? dunno yet..... it will be getting a CAMS spec cage so I can do offroad racing but Ill keep the chassis and body to Challenge class CCDA spec so I can race winch truck if I want to.

Just for reference, the acert cat motors are compound turbo, they only gave 1 egt probe, in the exhaust after the 2nd turbo... Here's a pic I prepared earlier. They do take a very long time to get up on the gauge too... mind you, they are a 15l with slightly more power than a d22 motor lol. That one was supposed to be a 625hp...

Its misleading as the exhaust gas goes through another turbo (and thus loses heat) before reaching the probe. I think exhaust manifold will be the safest bet

If the turbo is off the manifold its pretty easy to drill and tap just before the turbo flange...you want the hottest temp you can find at this level of tuning.

bods said:

Just for reference, the acert cat motors are compound turbo, they only gave 1 egt probe, in the exhaust after the 2nd turbo... Here's a pic I prepared earlier. They do take a very long time to get up on the gauge too... mind you, they are a 15l with slightly more power than a d22 motor lol. That one was supposed to be a 625hp...

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Would pre turbo temps on that beast be frightning?

camo.b said:

Would pre turbo temps on that beast be frightning?

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I would probably say so. I saw it get close to 550c once, that was towing 3 trailers and 50c ish outside temp. Even going hard up hills it never got much over 350c... they aren't built to rev though, they are only really good up to around 1600ish rpm. They run around 50psi at those revs. Being all steel and cast iron though, they don't have to worry as much about melting pistons or blocks hahaha

dilmah said:

Its misleading as the exhaust gas goes through another turbo (and thus loses heat) before reaching the probe. I think exhaust manifold will be the safest bet

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Yep, I'd definitely agree with that. I think the small turbo was gated at 21psi. The second turbo has no wastegate at all, max boost I'd say is limited by fueling, between 47 and 50psi depending on ambient temp.

I can get Auberins gauges pretty cheap ($80ish delivered), running one in the exhaust manifold pre turbo, post primary turbo and post secondary turbo is no big deal. I plan to run an oil temp and pressure, water temp, tranny temp and wideband O2 (for AFR's) when I redo the dash anyway. Its the Navi's job to monitor the gauges so I don't have to worry about them. Plus they will aid in tuning as well. the more parameters I can monitor the safer the tune will be.

dilmah said:

I can get Auberins gauges pretty cheap ($80ish delivered), running one in the exhaust manifold pre turbo, post primary turbo and post secondary turbo is no big deal. I plan to run an oil temp and pressure, water temp, tranny temp and wideband O2 (for AFR's) when I redo the dash anyway. Its the Navi's job to monitor the gauges so I don't have to worry about them. Plus they will aid in tuning as well. the more parameters I can monitor the safer the tune will be.

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absolutely, thats the way to go. datalogger would be nice as well
be interesting to see the temp drops across the turbo's throughout the boost range.

Wonder how long it will take me to snap the crank! I know a guy running 37psi in a TD42 silver top and that let go the other day, was making 230+ rwkw's. Don't think ill get that with the nav though

How long had it beed running a that level?

a while. gets thrashed as well