Turbo 325

[bangn]

So its been a hot minute since the last post. To be honest things have not been smooth sailing.

I researched a machinist, met the guy first and had a good conversation about my project. Really easy to speak to and felt confident in handing over the job. Told me worst case scenario would take three to four weeks
. cool im ok with that.

well it took 8 weeks. Gave me various dates he failed to deliver on and refused to communicate until I got pissed off. My crankshaft was sent to two other businesses for ballancing and grinding that I didnt know about.

So i get it home and start weighing my individually balanced parts. Nothings numbered. How do I know what rod goes with what pin? What piston goes on what rod? What piston goes in what pot? I weighed the pistons and they are essentially balanced to 1g tollerance instead of .10g. The pins hadnt been touched. In the end I had to weigh every component and swap round parts until my piston/rod assemblies were even right down to the circlips. The crank was balanced well but baffles me why would you go to all that effort to do an entire rotating assembly and not record final weights or number anything.

So i decided fuck it, measure it up for assembly.
Piston to bore is perfect, big ends perfect, did a great job of the Intermediate shaft bearings. Mains measure up with 3.5 thou of oil clearance. What the f.

Call the machinist and I find out he didnt measure the tunnel with a bearing in it as thats not the industry standard. Fantastic. So i took the block somewhere else to get a tiny amount shaved off the main caps and the tunnel line honed to get it back where it needs to be.

so that took another 4 weeks and is now up to 3k in machining/ballancing costs just for the bottom end.

Very stressful but can say now everything is now correct and clearances and component weight assemblies are spot on. This is why you should always check machine work. Every time.

now the next hurdle. The top end!

[bangn]

I picked them up from bimmerheads but they said the schrick dual springs are the go

[hasa]

I like the bigger pad design. Hoping of course that the geometry is right.

Did KM Cams give any recommendations about spring rates for these? Obviously valve train inertia is somewhat higher than with aluminium rockers.

[bangn]

Yep, Vac Rocker locks. Basically just giving the rocker stability and stopping the chance of it slipping off.

So the steel rockers arrived, I put a rocker shaft in it and ran a 6mm stem through the adjuster hole onto both rockers to gauge how different they were in terms of rocker ratio/lift changes
Basically what I found is the centre of the pad is the same height and position as oem. KM Pad is a bit wider and a bit longer. I'm still going to measure them up in the head
so ive got some real data but I think any difference if any will be comparable to wear. At this point it seems the pad arc is comparable to OEM. Here's hoping the steel clamps the eccentric adjuster
with enough side load they don't move.

[e30davie]

Look at all these shiny parts. excuse my ignorance what is that red VAC thing? stops the rockers from moving side to side?

[bangn]

So head gasket arrived on a rocket ship, expecting rocker arms and intermediate shaft bearings to arrive in the next day or two. Then should be able to drop the bottom end off to the machinist.

Athena 2mm Cutring gasket, the rings are smooth for block side and have three cutting grooves for the head. Hopefully have some success with this as feel like a bit of a Guinee pig

[bangn]

Rods - difference between standard and the power adder rods is the wall thickness on either side of the scallop, adds a little bit more weight but its still lighter than the OEM M20 rods coming in at 539g instead of 638g






Very hard thing to find these days

[bangn]

Getting closer to having everything I need to start this engine build, just waiting for HG, Springs and a Belt

Details Below

M20 Turbo Stroker
2859.96cc
8.5:1 Comp
85mm Bore
Athena Cut-ring Headgasket
84mm stroke small counterweight 2242898 2.8L crank
Molnar 135mm Power adder H-beam rods
Supertech 1mm oversize valves with Inconel exhaust
Schrick 272/272 Cam
JE Custom Pistons with tuff coated skirts, deeper valve pockets, accumulator grooves & contact reduction grooves
KM Steel Rocker arms
Schrick Sport dual valve springs
VAC Rocker Locks
Gates Racing timing belt
ACL Race series bearings
Arp Studs

[bangn]

Yeh it runs a 3.73, one of the next things I think I will be looking at after the engine build as its likely part of the equation of getting it to build boost better. Bit more load would be good.

Keeping the 3071, being a GTX they out flow a non-gtx 3076 which is what I wanted initially but has better response. Seen some numbers made on other 2.5s (not M20s) of making 450-480rw with the gtx but we will see. Might have to be on E85 to get that yet.
I would rather have a better curve thats a handful than just have all this peak power Il never use on the street. As it is I've never taken it past 120kmhr (75mph), these days I just like to open up the tap a couple of gears and I'm happy.

[varg]

Good tires then, maybe you have worse traction than I do because of gearing. I do have a 3.25 rear end and though I break traction in second with any reasonable amount of boost and third gear at 20psi of boost, the car doesn't deviate much. If you're smoking tires and deviating now an extra 100whp will have you shopping for drag radials. Are you keeping the 3071R for the 2.9 build? I'd be interested to see if you can actually get 450whp out of that turbo even with the bigger turbine housing. The compressor would be maxed out for sure.

[bangn]

Tyres are Advan Neovas AD08R 235/40r17, It was a toss up between those and Proxes R888 but at the time there was zero stock available of the R888s. 235s in a 40 are pretty hard to come by and don't leave a lot of choices. Theyre the biggest tyre I could get under there without smashing guards or liners when turning. Fenders are rolled too. Tyres grip really well and become exceptionally sticky during summer.

Yeh i'm running a .82 rear housing so likely why. A .63 would of been perfect on a this engine. I have a shrick 272 for the engine I am collecting parts for, really trying to increase my midrange this time

Wiring is going to get a revamp, initially I made a harness to keep it looking OEM, but ive now decided I want to reroute things to make it look cleaner. Its possible I will be running a IC7 dash, DBW, traction control and flex fuel shortly and I would rather just build a harness thats ready to go to have those features and I can just plug in to the systems when im ready. Only annoying thing is I will need to buy an elite 2500 for the DBW.

[varg]

Very nice car, sounds like you're quite limited by your tires. I'm not sure what tires those are but it sounds like it needs to go up a performance class with the new engine

haltech elite 2000...
Has all the engine monitoring fruit to make the tune as reliable as possible, wideband, knock sensor, full seq ign and injection, intake, water, oil sensors ect.. All of which can be monitored by the CAN gauge in the vehicle on the fly.

I'd love to see some more of that. Custom wiring harness, knock sensor install. Very nice. That's a lot of work, speaking from the experience of having done it on a simpler car of my own years ago. That's a very similarly sized turbo to my 60 trim T3/T04E which I run with a 0.63 AR housing and 57mm turbine. Your peak torque is later than I expected given the stock camshaft. Mine peaks somewhere between 4,500-5,000rpm with an IE 272 cam.

[bangn]

Na no spacers, yeh keeping the 260 for now but I'll try keep it going with this setup as long as possible even if it runs Into issues.

[AusScare]

Looks great! I'm also in Aus (Brisbane). Did you end up having to run a spacer with those front brakes? Wheel fitment is a nightmare when they get that big.

[e30davie]

Interesting. Going to keep the g260 with the new setup? There are getting few and far between over here in Queensland...and when they do come up they are $$$. Im tempted go look at other gearboxes even just for peace of mind.