Turbo 325

[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]

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.

[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]

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]

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

[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]

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.

[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]

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

[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!

[Panici]

Seems like it's becoming impossible to find a machine shop that does good work.

The 24v head I had skimmed and hot tanked came back with valves hung open because of crud on the seats. Glad I inspected closely.
That's a pretty easy job in terms of machine shop work. I'd hate to see what they'd do to a bottom end.

[varg]

Ouch, sorry to see. It is going to be a seriously cool engine though once it's together and making power. Not numbering anything is stupid, how hard is it to get a paint pen out and mark stuff? Seems a lot of people have been complaining about their local shops going downhill lately. The frustrations I've had with bad parts over the past few years has me wondering if this hobby is going to be more frustration than enjoyment for me in the future, was it always like this? I don't know. I couldn't afford to do fresh builds with new parts until the last few years and junkyard parts always just worked for me my whole life

[bangn]

Its funny you should say that Varg, I said the same thing after I picked up the block to a friend of mine. The hobby is enjoyable until I ever have to outsource work, it seems to have gotten worse in the last five years. Companies are just not interested in delivering things in a reasonable time frame, do not communicate effectively (had a few ghosters) and seem to be either way too busy and/or lost their passion due to dealing with the ever increasing customer expectations. I have an M52 disassembled ready for a rebuild for another e30 and to be honest given the experience i've had I am tempted to just bottle brush it and do everything at home exception to facing the head. Things go fine when I have control.

The 24v head I had skimmed and hot tanked came back with valves hung open because of crud on the seats. Glad I inspected closely.
That's a pretty easy job in terms of machine shop work. I'd hate to see what they'd do to a bottom end.

yep this is the exact issue, I swear they test the water and see what they can get away with in terms of doing the absolute minimum hoping the customer is uneducated enough to notice

[bangn]

So received the head back and for once things went pretty well with the headshop I picked, never used them before so was a bit of a gamble like always. light face performed, multiangle seat job for the +1mm I&E, guides were pretty worn so k liners were used.

However I did hit a snag once I got home lol, I started weighing all the valve train components to start balancing out the top, I got to 8 valve springs and found the company I used for the Schrick products accidently short shipped me.
so I reached out a few weeks of delivery and they rectified the issue without a fuss and shipped out the missing ones with DHL. So I should have in a couple of days. BAR-TEK are great and I wouldn't hesitate using them again. Mistakes happen.

so in the meantime I did PTV clearance, found I have a fair bit more than I thought id have with the 1mm oversize valves, I didn't stuff with the ports too much as they're not the easiest things to improve without a lot of R&D, a flow bench and CNC machine
So all I've done is delicately taken out casting lines/steps to aid velocity.

[bangn]

Finally got this thing off the engine stand. Spent a bit of time weighing the valvetrain to equalize the weights in the top end, Its pretty surprising when you buy new parts how much their weights can vary. Graph below is the final weight of each assembled valve assembly. Pretty sure its going to be smooth in that top end now. Scary to think if this wasn't done its possible to get a valve assembly to weigh 266 grams instead of 263.

INTAKE	Valve	Spring Outer	Spring Inner	Top Retainer	R/arm with adj	Total - g
1	72.17	42.88	17.76	15.55	115.64	264
2	72.6	43.73	17.37	15.26	113.45	262.41
3	72.44	42.98	17.74	15.53	114.61	263.3
4	72.2	43.3	17.56	15.34	115.59	263.99
5	72.43	43.44	17.38	15.29	115.49	264.03
6	72.47	43.17	17.6	15.5	114.27	263.01
EXHAUST	Valve	Spring Outer	Spring Inner	Top Retainer	R/arm with adj	Total - g
1	70.77	43.19	17.55	15.5	116.29	263.3
2	70.58	43.16	17.67	15.43	116.41	263.25
3	70.78	42.83	17.94	15.5	116.15	263.2
4	71	43.16	17.7	15.4	116.07	263.33
5	71.49	43.08	17.73	15.41	116	263.71
6	71.53	42.84	17.81	15.58	115.96	263.71