Turbo Techno

[POS carb]

I wanted to put a thread together with good tech info on turbos because I am getting lost with all the discussions in the search

ok turbos make boost
I know that and I know a wastegate lets extra exhaust gas past the exhaust wheel and blowoff valves vent the extra intake pipe pressure when you shut the throttle but turbo still has inertia...
I know you need to tap oil feed and return

Stuff I need to know
Selection:
What is a good A/R for a 2.0 A20, power up to 6500 RPMS? Should I choose a t3,, t4. etc? I prefer drivability with a slight dropoff at the top end but really I'm looking for a turbo that can feed it up to at least 6K around 10 PSI

Construction:
When constructing a manifold, are there particular metals I should use/avoid?
What about the welding (tig, mig, etc)?

Ignition:
When boosting I heard that timing needs to be retarded under boost... about how many degrees? Is there a ballpark level or a formula to calculate that? Or do I just try and keep the engine knock level down? Since our distributors are vacuum advance, wouldn't that kill the advance when the turbo makes boost? I think that'll bring it down to the base timing plus whatever the centrifugal ammount is. Maybe I can just retard the distrib a lot and run both vacuum advances for drivability at the low end?

Fuel:
how do I calculate the fuel (lb/hr) requirements for a boosted application?
How does boost affect fuel delivery? I assume it is harder for an injector to push fuel @ 10 PSI vs at 0
I would need a fuel pressure regulator with "boost sensing" right?

ECU
For low-boost applications, can it be as simple as a better fuel pressure regulator that changes the fuel pressure in proportion to the manifold pressure and still remain stoich?
Can I just run a MEGASQUIRT ECU with the right MAP sensor and a wideband O2 sensor and use some kind of other Honda distributor or some other multiple-coil ignition (the megasquirt doesn't control ignition)?
I've read that most Honda ECUs can take up to 11psi, can't I just use any other OBD1 Honda ECU and hook up a Hondata kit to it as long as I hook up the essential inputs like Crank angle, cam position, coolant temp, etc?

Camshaft:
Is it true that our cams have no overlap? I find that hard to believe.. either way wouldn't some overlap acutally help the turbo spool up better by introducing pressurized air to the cyl before the exhaust valve closes?

I'm sure I have a bunch more questions but those are a few to start with... any takers??


Facts (i.e. numbers, experience) are better!!!!

[POS carb]

fuck it then I guess I'll just break parts till I figure it out like I always do

[A20A1]

The J&S unit is supposed to retard the timing when it senses knock but tries to bring it back up... that way you don't keep retarding all the time.

https://www.3geez.com/showthread.php?t=37169

I listed Engine management with links... on post #6 there is a link for fuel flow calculations.

[A20A1]

Camshaft:
Is it true that our cams have no overlap? I find that hard to believe.. either way wouldn't some overlap acutally help the turbo spool up better by introducing pressurized air to the cyl before the exhaust valve closes?
I'm sure I have a bunch more questions but those are a few to start with...

I'm pretty sure our cam has overlap, when adjusting valve clearance you can see when both the intake and exhaust valves are open... also you can look at the cam lobes themselves.
It may be good if the fresh charge displaces the exhaust gas... maybe less contaminated air fuel mixture once the valve closes, but it doesn't I see, hehe I forgot about the pressure difference.

[AccordEpicenter]

You generally want less overlap because too much causes reversion and it sucks the exhaust back in the cylinder. It happens because your exhaust manifold pressures are always greater than your intake manifold pressures in a turbocharged car when in boost, so a rough guestimate on my setup is that i have maybe 30psi exhaust pressure in my exhaust mani, and the 13psi boost in my intake... For turbo size, id say it depends on how much you wanna spend and how much power you wanna make. For what you wanna do, a Garrett T3 60/48 (thats a 60 trim compressor, and a .48 a/r turbine housing) should have good results. You can use a megasquirt but youll have to figure out how to hook it up. You can also rewire to an obd-1 honda ecu and rock that too. As for timing, id say a fairly good starting point is around .7 degrees per lb of boost you should retard the timing, you can usually set this with an MSD BTM #5462 on a stock ecu or a honda obd1 ecu. Ive ran a stock ecu with an MSD BTM and Apexi SAFC and mitsubishi 450cc injectors with a walbro fuel pump with no problems at 10psi. Its a bit inadequate for the 13psi im running now. Dont even think about running just a Fuel pressure regulator or FMU, ask justin or adam how well that works. Pretty much anybody ive ever seen relying on one blew their motor sooner or later. Hope this helps

[Swap_File]

I looked into doing a megasquirt, but doing an OBD1 Honda ECU swap seems to be alot cheaper and easier.

For wideband I plan on picking up one of these:
http://wbo2.com/2a0/default.htm

The kit is about $250 with sensor for the 1MB version, without display (displays can be hacked together spare parts).

[Kabuki]

The OBD0 Civic/Teg ECUs are less wiring and can do just as much for Turbo. in fact, check out TurboEdit at pgmfi.org. Of course, OBD1 would use Crome or Uberdata (go Crome!). As for sensors, I can ship out L2H2 (NTK) sensors for $110. Or the LSU (Bosch) sensors for even less.

[POS carb]

thanks I will check that out

I found out old Saab 900 Turbos use a completely mechanical distributor for turbo, with boost retard and everything. I wanna get one and check it out, maybe it can be made to work w/ the accord.

Would there be any point in using an MSD Blaster ignition box in conjunction withthat boost retard timer? It looks like that device controls the coil completely.

[Swap_File]

The OBD0 Civic/Teg ECUs are less wiring and can do just as much for Turbo....

What distributor is used with this setup for timing advance control? I have not heard much about this ECU swap.

[gfrg88]

The OBD0 Civic/Teg ECUs are less wiring and can do just as much for Turbo. in fact, check out TurboEdit at pgmfi.org. Of course, OBD1 would use Crome or Uberdata (go Crome!). As for sensors, I can ship out L2H2 (NTK) sensors for $110. Or the LSU (Bosch) sensors for even less

even if you were to use this ecu you would still need to change/adapt another distributor cause ours are vacumm advance, i think the best way to go is to pm justin86, he can make a whole obd 1 conversion, anything you need to turbo your car, pm him for more info...

btw good luck with the build....

[AccordEpicenter]

The OBD0 Civic/Teg ECUs are less wiring and can do just as much for Turbo. in fact, check out TurboEdit at pgmfi.org. Of course, OBD1 would use Crome or Uberdata (go Crome!). As for sensors, I can ship out L2H2 (NTK) sensors for $110. Or the LSU (Bosch) sensors for even less.

OMG! A N00b that knows somthing! Yeah, PGMFI.org is a great resource for the honda ecus and chipping etc. Crome is easier to use than uberdata too. Yeah, you can go with obd0 civic etc ecus and TurboEdit is just fine to use, I have mostly obd-1 parts lying around so thats why im going obd-1 lol, simple as that. Obd0 or Obd1, either will work just fine

[Swap_File]

Next week I will have to grab an OBD-0 Civic Distributor and try to fit it to an A20 at the junkyard.

I have not been able to find any OBD-1 ECUs or Distributors, they are always gone immediately, but I see the older Distributors and ECUs quite a bit.

Any idea what other sensors would need to be upgraded, if any?

[Swap_File]

I just spent several hours searching through 3geez and on preludepower.

I guess the whole OBD0 Civic ECU thing never worked out for the A20 or B20/B21 engines, because none of the distributors would mount or fit properly with the heads. Going OBD1 is probably the best bet.

Also, the stock OBD1 distributor on the Prelude B20/B21s had to be replaced by Civic/Integra OBD1 Distributors for the upgrade.

[AccordEpicenter]

The other alternative is to stuff the obd-0 civic dizzy guts into an accord dizzy, but it sounds like more work than its worth, especially if you can go obd-1 easier. Tons of guys are still using obd-0 civic ecus for turbo hondas though.

[POS carb]

Cool. I had seen the PGMFI site hacks but most deal with distributors with electronic ignition advance... I'm going to look for a CIvic disributor.

Are the late model CRX dizzys the same? I saw a SOHC 16 valve one at the junkyard last time.

[Swap_File]

According to PGMFI, these ECUs are all similar, and should work fine with turboedit on the 3rd generation Accord as long as we can get one of the distributors from the same/similar car to fit:


"OBD0 MPFI" (88-91 MPFI *Non*-Vtec Civics, Integras)
The following ECUs all share a common circuit board design(with some minor differences):

* PG7 : 88-89 Integra (D16A1 - Electronic Advance)
* PM6 : 88-91 Civic/CRX SOHC Si (1.6l SOHC)
* PM7 : 89-91 Civic Si DOHC ZC (JDM EF3) (Euro A20A Also reported by Mark Lamond)
* PP5 : 88-94 inc PP4. Honda Concerto, UK Rover 216, 220, 416, 420, GSi, Gti, ???
* PR5 : 90-91 JDM Integra ZXi (1.6 sohc)
* PS9 : 90-91 USDM Civic EX (1.6L SOHC - usually auto)
* XE5 : 88-91 (dates questionable?) Mugen Race platform (ZC)
* PK2 : 88-91 Prelude (Accord?) Generation 3 B20A Engine

The PM8 and PR4 each have unique circuit boards, although their code is mostly compatible with the other ECUs in this family.

* PM8 : 88-91 CRX HF (Euro ZC also reported)
* PR4 : 90-91 USDM Integra LS/GS B18A1 (note: OBD1 PR4 exists too)


The PM6, PM7 and PR4 seem to be the most common in use on the forums.

When I searched 3geez before, people did not seem very specific about why the Civic/Integra distributor swap would not work, they just said "It wouldn't fit". Maybe it just needs a custom mount or something.

Edit: I did see this: https://www.3geez.com/showthread.php?t=28248 "The teg's distributor won't fit, the thermostat housing is in the way."