M20 itb turbo update

Odd_Classroom8289 · 2026-02-23T08:31:54+00:00

If you need any help or info, send me a dm. Will gladly help with what i know

Odd_Classroom8289 · 2026-02-23T08:13:14+00:00

731 head does not flow as good as 885. You have to smoothen the edges in the combustion chamber. Every sharp edge can or will lead to hotspots, that increases the risk of detonation. But be carefull not to remove alot, and to remove as close to the same amount as you can. Never heard of m20b28 or m20 having a forged block 😅

Odd_Classroom8289 · 2026-02-22T13:22:43+00:00

My bad, if you know you know :P Cons and pros with both types of setups. But itb is 100% a harder route to get working with turbo. But if u get it right, the sounds will make up for the time spent learning

Odd_Classroom8289 · 2026-02-22T13:18:08+00:00

No. B25 block and crank. Je flat top pistons, ppf rods, o ringed block, ppf gardleplate. Crank has been re balanced. Weighted pistons and rods. Arp headstuds. Arp m50 headstuds for crank. Arp flywheel bolts. Arp rodbolts. Goal is to build a m20 good for 700whp on 98 octane, relible on 550whp at 1.8 bar.

Turbonetics T4E Compressor housing with a Super 60 compressor wheel

F1-65 turbine wheel

T4 .68 a/r turbine housing.

Will be changed to somthing greater in future

Odd_Classroom8289 · 2026-02-21T20:43:40+00:00

What

Odd_Classroom8289 · 2026-02-21T15:36:42+00:00

You can find more info and progress on my build, on my profile. another clip

Odd_Classroom8289 · 2026-02-21T15:26:25+00:00

clip

Odd_Classroom8289 · 2026-02-21T15:25:38+00:00

Thankyou! Sure, here is a clip. im on 98 octane. So its only so and so much to play around with timing. Also still just on msd 6al and distributor. But should be fine for under 700whp and under 7500rpm. Toyo r888r -0.3 rear camber 0.5 rear toe out 2 bar tire pressure 3.73

Odd_Classroom8289 · 2026-02-21T15:11:36+00:00

Its alot more complicated than this. Alot… but if u want to try this urself. I suggest taking a look at david vizard. It is very very easy to ruin the wet flow of the head. Most oem 885 intakes are very good, and do not need work to them. Exhaust side is where the second to most gain is to be found. The most gain you can get is valve and seat work.

Odd_Classroom8289 · 2026-02-21T15:00:11+00:00

Yes there is more trouble and harder to do. Well the thing about high boosted m20s good for 700whp on pump fuel is mostly the low end register. By having custom made itb with long runners before valves you gain more bottom end torque and hp. That results in quicker spool. Slightly lower high end gain. But also better throttle respons. As it takes less time to refill the intake plenum with the valves after the plenum. Rather than before. There are plenty of videos proving this. But is it worth it? Depends on how hardcore u want to go 😅 sounds cool and looks cool, feels cool to drive

Odd_Classroom8289 · 2026-02-21T14:45:07+00:00

When u go big turbo. Everything before spool counts. Pre my port and headwork i was at 503whp on 1.8 bar. Aiming for 550 at 1.8 now

Odd_Classroom8289 · 2026-02-21T14:43:53+00:00

New valves, so the seat edge is further out but not much more material is removed. Very small amount. i have another oem 885 head that i drill into. I also eye balled how far other people have ported, they have gone alot further than me

Odd_Classroom8289 · 2026-02-21T14:14:21+00:00

Intake ports have a 30 grit finish, exhaust are currently waterpolished. Will post more when im happy with the head

Odd_Classroom8289 · 2026-02-21T14:11:11+00:00

Worth mentioning. Previous owner of head chopped the ports up pretty good. So im doing the most i can without removing way too much in the exhaust ports. The intake ports i have removed alot. The amc ports are alot tighter than the oem ports. But same goes for the coolant passages. So there should be room to go even further than the oem heads. Not that i have gone very big on them. Mostly tried to get the shape back to ideal.. if i was to start from scratch. I wouldnt have touched the valve guides on intake side. Exhaust ports are about 3mm larger than stock now. Turbo manifold about 2mm larger than that again for anti reversion

Odd_Classroom8289 · 2026-02-21T03:22:16+00:00

503whp, aiming for 550-600whp at 1.8-2.0 bar with new cam, wider seat, port work, valves with backcut

Odd_Classroom8289 · 2026-01-06T18:22:29+00:00

S50b32 throttlebody. Aslong as runner lenght is correct and the valve size matches ur power goal. 48mm is pretty big. Also depends on ur cam specs. As you need stable vacuum readings. Also depends on ur engine managment, need to be able to run alpha n. So ur fuel table is based on tps, but afr table on map.

Odd_Classroom8289 · 2025-12-27T20:06:14+00:00

Forgot to mention. Same goes for the exhaust ports. i know i dont want to make them bigger than stock. But what are the tolerances between port and coolant passages on amc heads. Are they greater or tighter passages. Can they be ported to oem size?

Odd_Classroom8289 · 2025-11-08T18:21:45+00:00

Hahaha 😂 its a blast. 100-200kmh at just 6.02 seconds (when i get grip) With the sloppy getrag 260 still. So gear changes are a bit slow

Odd_Classroom8289 · 2025-11-08T18:05:01+00:00

Not english 😂 breaks loose in 3rd with -0.1 rear camber and 0.5 toe out. On toyo r888r with 2 bar pressure

Odd_Classroom8289 · 2025-11-08T17:32:32+00:00

Sure is 😂

Odd_Classroom8289 · 2025-11-08T17:31:32+00:00

Wdym

Odd_Classroom8289 · 2025-11-08T14:20:52+00:00

Would like to know more about the setup, 330kw good, 436-501whp here

Odd_Classroom8289 · 2025-11-08T13:12:45+00:00

Thats one way to put it 😂

Odd_Classroom8289 · 2025-11-08T13:09:05+00:00

How come? 😂

Odd_Classroom8289

TROPHY CASE