Turbo/half-bridge running a piggy-back ECU...?!?!?! (also, scored side-housings)
 

Anyways, my motor is apart right now and I'm rebuilding it.

I'm using the housings from a 'previously rebuilt' 100k mile coolant-seal failure motor. The side-housings have minor scoring on them, which I believe came from normal use... Will this be a problem?

I'm sure someone here know's what I'm talking about, since all 4 of the motors I've torn down have had these 'lines' on them; across from where the intake ports are.

I've lightly wet-sanded the side housings using a flat-block and 220 grit sand-paper (with a 400 grit finish), but the 'natural' scoring is still clearly evident and I CAN catch a nail in it... I don't have the money to get new housings, so I'm just shaking my head and saying "whatever"...

Also, is there a problem re-using my FD corner-seal springs and Atkins apex-seal springs, which have less than 10k miles on them?

I'm not expecting more than 50k miles on this motor, so what do guys think?

Anyways, right now I'm in the process of porting everything and I really want to experiment and maximize everything. I'm seriously considering doing a half-bridge port, only because I was told by the resident 'porter' at Atkins that I could run a half-bridge on the stock ECU with no problems...

Now, this is contrary to popular belief, so I'm wondering if he's correct...?

If he's "clearly" mistaken, why?

WHY would a half-bridge need a standalone? Is it because the timing has to be changed? Fuel? ... ?

Also, would the problems a half-bridgeport causes, be experienced in the HIGH RPM's or the LOW?

I'll be running:

8:5:1 rotors
R-tek 1.7 (timing retard etc.)
SAFC II
Walbro 255 fuel pump
550/720 fuel injectors
Hybrid TO4B turbo, with a heavily ported WG
3" TID
80mm exhaust
stock TMIC

What specific problems do you think I'd encounter from bridge-porting the secondary intake ports?

Also, what's the max boost I could safely run with this setup?

Thanks, and feel free to logically shoot down my idea...

If it's determined that a half-bridge is too risky, I'll just do a large street-port.

I wouldn't spend the time to do what you are trying to do and run a piggy back with the TMIC. I'd add a better IC and stand alone to that list and you won't be disappointed or out lots of time and money.

Is there a problem with bridgeporting now and standalone later?

bridge requires unique timing and lots of fuel...you want to trust a piggy back for that?

I guess I just don't understand how a bridgeport allows so much more airflow than a large street-port... For example, let's say you left the secondary intake port STOCK and just cut a little eye-brow next to it, how is this allowing radical amounts of air in?

Its opening alot earlier and theres more open area for the charge to come in at. I agree with dubulub in going intercooler, standalone, fuel, then motor.

It's a pretty radical departure from stock stuff. A "little" eye-brow will induce tremendous amounts of overlap into the motor. This has a dramatic effect on how it runs. The engine will honestly need a real standalone to run properly if you're wanting to go the HBP route.

B

Soul Assassin was running a piggyback on his halfbridge. At least I think it was a piggyback, I remember him saying something about being limited by the stock ECU.

He ate a couple engines, too, as I recall. Dunno if related.

Other people have done it, but didn't like being limited to the stock redline.

I am thoroughly confused as to what overlap is... I cannot seem to comprehend it mentally... lol.

I know that it's roughly when the intake and exhaust 'overlap' in their respective cycles...

But I imagine that the 'overlap' would come if you extended the intake port 'up' and the exhaust port 'down'... A bridgeport is to the 'side' of the intake port, in a sense, extending the intake port 'sideways', not extending it up and down (what I see when I envision creating overlap).

Does overlap then refer to how MUCH air is coming in???

And not necessarily the up and down timing of the exhaust/intake...?

shoot... Help...? lol

Overlap is when the intake ans exhast are both open at the same time.

You got it backwards. Since the rotor uncovers the port from the side as it rotates, the more you port over to the side the earlier it is uncovered. With a bridgeport the new port is opened up or uncovered while the rotor is still pasing over the exhast port(which is still open). So you get overlap or the two ports being open at the same time. Try looking around this website http://www.rotaryengineillustrated.com/

^ I see... Anyone else care to comment?

So... It appears the only major problems be experienced in the lower RPM's (and idle)?

What about higher RPM's?

BTW, I'm getting a FMIC here shortly, so I'll have that installed at the same time the motor's going in.

what kind of comment are you looking for...we're about to vote you off this island for not listening.

I said you'll save money if you do it right...what else can anyone say to convince you??? you want to run piggy backs, do a street port.

WTF?

Well, I asked 5 or 6 questions that no one answered.

Regardless, I've decided to go with a large streetport in lieu of bridgeporting. Thanks for 'schooling' me guys.

bridge port changes the port timing across the board.



you made a wise decision