2.2 Stroker DOHC by STW

[fredio54]

Gutted! :-(

Or : sleeve it! ?

[STW]

Sleeving, hmm I was always planning to do a second built after this one, and hey, I just got a perfectly busted block that wouldn't mind sleeving

But I'll just get a replacement for this one, I got it for pennies really.

[Nealio]

Quite the ambitious project.

[STW]

Thanks

Next friday (tomorrow) I'll get to see if the SR20DET pistons can be made to fit the engine. They would suit otherwise, except the C/R is too high, 9.3:1 or so. If the dishes can't be deepened enough (The stock dish is +12cc, I need about +18cc), the option is to get full dome pistons and machine them to fit. It'll cost almost $1600 though, so I'm not terribly enthusiastic about it. 8.5:1 is where I'm aiming for, with good gas 30 psi should be fine.

Well, perhaps NEXT week will bring more progress.

[fe3t b2200]

i have ross forged sr20 det pistons in my 2.2 rx7 only need to machine valve pockets into them and have the little end of the rods machined narrower

[chief tool]

I bought Mahle forged SR20DET pistons for my stroker....but I havent got as far as fitting them to the engine yet, I am waiting for the scat rod bulk buy to go through. I havent worked out the theoretical C/R....

Fe3t: what was yours ?

[STW]

Good choices, I must check them out if Wisecos are no-go.


Meanwhile, here's something from tonight.


Got a bit venturous with the polishing wheel:


The engine is not going to be a polsihed showpiece though the rest of the engine will be mostly black and red

Plug threads were fouled pretty good:


+

=


I like how good the threads turned out to be


The main subject however was this:


I started working on the VICS. These are worked ports, with no sharp corners. There was a slight cast defect at the 5pm position on the #4 runner, I tried to smoothen it. I wonder if I should still increase the radios and make them more smooth, but at that stage they're quite a bit more smooth than stock. For comparison, here's the two unworked ports:

[chief tool]

I just remembered I cc'ed the Mahle pistons some time back and posted the info in a different thread....

theyre about the same as stock, 11.7cc

Which I guess means it'll end up with a 9.2:C/R except that its stroked so it'll end up being about 10% more at about 10:1

Probably OK for the 10-12psi on 98RON with water injection that I am planning...

at 30Psi I'd want about 7.5:1

[eraezer]

Nice project

And I see that you also decided to polish the fuelrail a bit I didn't have the patience to completet it though.

[STW]

Went to see the pistons today, things are looking great! The skirt is teflon coated, and the dome is 12mm thick, plenty enough to machine valve reliefs and dish! I'm going to talk about it with the machinist monday and pick them up tuesday.

Radiused the rest of the ports today. I think in fact it would be best to leave the butterflies open just a crack, so there's just a slight flow through the big port, to keep the high velocity flow from through small port from going turbulent at the junction.... A dyno run will give answers.

Also, I measured the exhaust valve. head diameter 29mm, stem diameter 5.95mm, length about 104mm, tip length 3.5mm

Now, here's numbers for Subaru valve from Ferrea catalog: Diameter 32mm (33 oversize available), stem diameter 5.96mm, length 104.75mm, tip length 3.5mm

... match?

Finally, something I picked up from the hydraulics shop today:


Those are for the in-tank pump setup, a bit small but only for a short short distance! The tank access panel is so tight there's no way AN-6 parts could fit through. I'm thinking of making a whole new pump bracket from aluminium, the current item is bent, rusted and leaky POS.

[bpt323]

are you speaking of a subaru intake valve? as a 3mm overstock size valve would be a challenge if possible to fit right??? or am i wrong

[STW]

ACtually, just exhaust. Anything over 1mm larger wouldn't really fit the DOHC head..

[STW]

here's how the lower manifold looks after a bit of radiusing:




Enough of that. Next tool...



meet mr. FleshGrinder... a metal saw on an angle grinder, goes through half an inch of aluminium in a second without effort. The most dangerous tool in the garage.




First cut with the grinder. The edge will be radiused right down to the edge, so the missed cuts will be completely removed.



Opened a bit more. The idea is to remove the wall so the two chambers are joined seamlessly.

[fredio54]

Looking good :-)

I still say a circular saw with no guard is worse though :-)

great for freehanding firewood, not so good if you let it go.

the grinder wont get as far on its own.

neither of my grinders have guards either. get in the way too much.

it's surprising how little you will be able to take out of that wall actually. I was thinking more, but if you go any further much you will mess up the entry to the small runners.

Keep at it.

Fred.

[Casejunkie]

That's looking good man. It's a shame I cann't give you Karma at the moment.

Question: Are you going to port/polish the head?