best mickey mouse m20?

[jeffnhiscars]

yes, I did, several years ago in fact. :)

sure, there's a power bump from the head swap - but I stick by you're not going to get anywhere near 200whp on an eta / 731 swap, without the ITBs, head porting, cam, larger valves, and custom tuning that engine had. Not exactly a "mickey mouse" build right? :p

Hah...So do we need to start a thread to define "Mickey mouse" lol

In fairness I did say itbs and properly done head w cam, valves, etc etc. not exactly Mickey Mouse but I see that as less work and $$$ than doing a long block with mix and match parts. By the time you freshen it all & throw in machining seems like a full blown build to me....no ?

[digger]

That bottom chart says it's a 320i, top says 325e. Are you sure they are the same car ?

Digger you and I have discussed eta options at length in various threads and the consensus (to my mind anyway) was always that the 731 would yield higher compression and over all better results in a NA install PROVIDED the head was done right.

Granted dropping a stock 731 on an eta may not be worth th trouble and for sure if you go FI the 885 is a better route. Don't make me question the effort and expense I've put in to this 731 I built with input from both you AND Rama lol

The 325e was in an accident and everything was swapped into a new 320i chassis. I don't doubt a better head would be better than doing the 885 swap onto an e bottom end. The only point I was trying to make is that the headwork has to be done well.

Rama has proven that the 731 has potential. His 2.7l had a head done by a reputable guy and when he did his 3L he built a flow bench and bought a Mira centronic machine and did a ton of R&D to work out what works and what doesn't

[jeffnhiscars]

The 325e was in an accident and everything was swapped into a new 320i chassis. I don't doubt a better head would be better than doing the 885 swap onto an e bottom end. The only point I was trying to make is that the headwork has to be done well.

Rama has proven that the 731 has potential. His 2.7l had a head done by a reputable guy and when he did his 3L he built a flow bench and bought a Mira centronic machine and did a ton of R&D to work out what works and what doesn't

We are saying the same thing....only you're saying it upside down ;D

Now that we are in FL maybe I should ask John to put my uninstalled 731 on his flow bench, then do before and after pulls

[digger]

Not really, I referenced the eta + 885 swap in the last post

I doubt a mild ported 731 on eta would do any better than the proper "I" based 2.7/2.8 all else equal. Do whatever is easier and you have acesss to.

As ff said it's easier for higher comp and you can use a flat top with 731 but these aren't an advantage as you have all the bits you need and the 2.7 "I" based stroker has a slight edge in compression when it's done properly ( block decked)

You should put it on his bench to check how well you did and then prove us all wrong

[SLEEPYDUB]

Did you read the link ? Head alone yes although more torque than a b25 but with the other upgrades done right you should be closer to 200 I think. I'm into my 731 for about $2k including stock motronic swap parts. Itbs, headers/exhaust and standalone should probably add another $3k

Lots of options for that much I'm sure.

That's a lot of money for 200hp

[jeffnhiscars]

That's a lot of money for 200hp

Keep in mind I'm including a cam, full motronic upgrade with virtually all new or refurbed parts. Headers and itbs are costly no matter what you put them on and whether you do a 731 or 885 the money is the same to,swap an eta head

[digger]

price up a stock rebuild m20b25 that gives 170bhp.......a mild built engine (using OE bits) always gives more BFYB when it is done well ( i.e. when you are smart about it and pay attention to details)

[jeffnhiscars]

price up a stock rebuild m20b25 that gives 170bhp.......a mild built engine (using OE bits) always gives more BFYB when it is done well ( i.e. when you are smart about it and pay attention to details)

I mentioned doing a head swap and motronic upgrade on an eta as an option to a full tear down since I stopped tearing down engines after my 3T truck was stolen and rolled and it's 6-354 Perkins spun a few bearings (did you know diesels will run upside down til they seize ?). Some of you pull engines more often than I change underwear. I get that.

Any head swap done right will cost the same regardless of which core you choose. I chose a 731 rather than an 885 for reasons that have been discussed ad nauseum. The motronic upgrade is mandatory. If you decide to do the bottom end with its own range of options, costs and benefits. Up to you how far you go, what you spend and what the ultimate goal is, but you're going to pay for a fresh head (like I did) no matter what.

As for BFYB how often is THAT front and center in our decisions as,opposed to "I did it cause I can" lol

[digger]

i guess in an absolute sense BFYB with a M20 NA is never there compared to other options.

i'm interested to see what results you get, did you do a baseline with the stock eta?

[jeffnhiscars]

i guess in an absolute sense BFYB with a M20 NA is never there compared to other options.

i'm interested to see what results you get, did you do a baseline with the stock eta?

NOW we can agree lol

Haven't done a pull yet but the head is not installed so there's time. After all this I feel I have to :)

[ForcedFirebird]

One of the local guys' endurance car stared out as an eta. With the exhaust gone (resonator only), PS, AC delete, it made 121whp 168wtq. Curious what a bone stock eta does with all accys and stock exhaust.

Jeff, the shop working your head has a flow bench? My bench is pretty close to superflow numbers. Really need to go ahead and buy the Pass Around Plates to do a fine tune (what most bench builders use to "calibrate" so everyone reads the same).

[jeffnhiscars]

One of the local guys' endurance car stared out as an eta. With the exhaust gone (resonator only), PS, AC delete, it made 121whp 168wtq. Curious what a bone stock eta does with all accys and stock exhaust.

Jeff, the shop working your head has a flow bench? My bench is pretty close to superflow numbers. Really need to go ahead and buy the Pass Around Plates to do a fine tune (what most bench builders use to "calibrate" so everyone reads the same).

Sounds like the deletes made up for drive train loss since I think those ratings are stock at the FW.

i had the machine work done in Charlotte and haven't touched the head since I picked it up....as in have not even lapped the valves which I do routinely. He does not have a flow bench and said his son does his porting and my conversation with him didn't give me enough comfort, so I did the unspeakable....and did it myself <flame suit on>. I posted this story back when but in sum, I used sanding cones rather than hogging bits to avoid taking too much off and followed the advice Rama gave me...

"ok bit hard to explain but the port almost takes on a slight D shape with the flat being on the short side radius or port floor, nothing drastic but just so there is a straighter flow path from sides of the port into the bowl and seat instead of the flow having to bend outwards where the port meets the porbowl. This is the main problem with just adding bigger valves if this area isnt widened to match then the advantage of the bigger valve seat and bowl is not really achieved. It becomes a lot more clear when you are actually doing it but im sure you can see what i mean :)"

If anything I took too little to be safe...mainly removed flash & cleaned up the guide bosses...which is why some bench time to optimize and equalize makes so much sense. Rama also suggested using the 323 intake since the ports are a better match to the 731 and I do have it.

The recap on the head is: new Osvalt +2 valves, new OE guides, new OE dual springs & new eccentrics, rockers refaced at Delta Cams, new I.E. 272. In other words, no corner cut.

If you can fit me in I do have an aunt near you who I should visit before she hits 90 so would gladly make the trip. Just have to find a time when she and her bf aren't in Vegas or on a cruise somewhere :)

[jeffnhiscars]

Just thought I'd add this for all you 731 nay Sayers...notnthat Gary knows anything :p

I would 2.7i the e block. The i parts just enhance the torque of the longer stroke. Its feels like a different engine to me, mid range torque is instantaneous. I used the 731 head from a EU 323i to keep compression up, and the cam they used on that model is fairly aggressive. I opened up the intake and exhaust ports some, just gasket matching the openings. BavAuto long tubes and free flow 2.5" exhaust. Took my buddy in a Z06 12 runs to beat my times in a NCCC Corvette sanctioned autocross last weekend, so its a quick motor that I run to 6,850 all the time and it loves it.

[ForcedFirebird]

Sounds like the deletes made up for drive train loss since I think those ratings are stock at the FW.

I find this on a lot of engines. Remove the inhibitors and stock motors seem to put down near brake power ratings (in a manual transmission anyways, autos rob power).

And yes, the m20 heads are touchy. It's very easy to gasket match and ruin the flow. I feel since the m20 intake gasket is actually on an angle in relation to the port, it's not doing as much as matching a gasket that's perpendicular to the air flow. You have to think of the entire intake tract as one unit - the very reason we like to flow our stuff with the manifold attached, along with the throttle body pinned open.

[jeffnhiscars]

Makes sense but since the 323 intake flange does not quite have enough meat to remove to port match tHe b25 TB I am planning to build a ramp in the tb out of jb weld so there's no step.

At that point it will be ready for the bench.

Have you had a 731 with a 323 intake manifold on your flow bench ?