T4 Pistons in the BHW Block!

[alphaseinor]

We've finally gotten around to put the T4 Pistons into the Kill Da Auto Passat Project car. Instead of ordering these from europe, I was able to source them a bit cheaper through Boraparts.com
Protrusion from the block was 1.05mm, exactly the same as the stock pistons.

Just look at that beautiful dish!

 

[TDIsyncro]

Nice looking pistons. Was this an oversize piston? Do you recall what the CR is or CC of bowl/reliefs is on this unit? Are those the factory valve reliefs? They look pretty deep. full 1mm or more?

 

[alphaseinor]

These are 2.5L 5 cylinder pistons from the T4 transporter... For a 1.9L IIRC it's 1mm wider bore to make it a 2.0L... since I already had a 2.0L in the Passat project car, I didn't have to bore, just hone it.

 

[mlemorie]

What are the advantages supposed to be for those pistons? BHWs are supposed to be the upgrade for the 1.9s, but Im always looking to improve upon my future to-do list.

 

[oldpoopie]

If I recall, these pistons need some work to them to make them work, correct?

 

[alphaseinor]

Oldpoopie: Based on the geometry with the BHW PD geometry, not as far as we can tell... Just a larger dish size... we'll see how it runs once it's done tho... not sure how many people have just stuck in the T4's. BTW, like your timeslips!

Mlemorie: The main advantage is a larger bowl, which drops the compression a little, also allowing for more fuel and air to be used without damaging the rods.

We'll know a lot more in the next few weeks when (and if) the LSD gets here for the MT 6 speed (please note this is a passat, not a GJB).

 

[O.C.TDI]

What about the oil squirters? The ones I have seen have the sprayers in the wrong orientation.

Would love to know since I am looking for pistons again.

O.C.

 

[oldpoopie]

What about the oil squirters? The ones I have seen have the sprayers in the wrong orientation.

Would love to know since I am looking for pistons again.

O.C.

Travis, the guy who I got my head from had 4 bhw pistons, the motor spun bearings, but the cylinders looked ok. I can see if he is still around and has the parts if you want. The motor had like 90k on it.

Or I may have a friend who'll do the piston machine work for us for real cheap.

 

[jjordan11]

I'm really interested how this turns out w/o machining the pistons. O.C. What happened to your pistons?

 

[O.C.TDI]

I'm really interested how this turns out w/o machining the pistons. O.C. What happened to your pistons?

Nothing... But to run big valves and such I will need to machine my pistons and since I like to keep my car running I figure might as well machine and coat a new set and swap them in then sell the old BHW ones.

 

[Mark@MaloneTuning]

What valves are you getting?

 

[alphaseinor]

The pistons don't need to be machined professionally, just need a drill and a cutoff wheel, then a dremel tool to get the ridges off.

Maybe I'll post a howto...

as for the valves, I've got a CNC head port program I'm still developing.

 

[TDIsyncro]

These are 2.5L 5 cylinder pistons from the T4 transporter... For a 1.9L IIRC it's 1mm wider bore to make it a 2.0L... since I already had a 2.0L in the Passat project car, I didn't have to bore, just hone it.

I was actually wondering if they were available in std oversizes, because the BHW pistons are not. I found reference to this piston being around 16.8:1 CR, so you must be building a pretty nice set-up!
What is the OEM valve relief depth on these pistons?

 

[TDIsyncro]

The pistons don't need to be machined professionally, just need a drill and a cutoff wheel, then a dremel tool to get the ridges off.

Maybe I'll post a howto...

I think I know what you are doing, but it would be nice for others to see.

 

[alphaseinor]

I did at least take photos of the process... probably will post later today or on monday.

Not sure if they come in oversize or not, you might ask Aaron K at boraparts

 

[TDIfreak]

Did you actually measure the bowl volume? 2.5 TDI has 20.5 compression so it just might come out smaller than any 1.9 bowl.

 

[alphaseinor]

Oh, it's visually larger... I'll be able to dim them tomorrow sometime.