NA to turbo conversion - questions and answers...

[mikeatrpi]

Let me rephrase...

 

Is it feasible to install dished turbo pistons in an F54 block and use a P79 head with a turbo exhaust manifold? Or am I better off running the flat tops and lower boost?

[nismopick]

Feasible... yes.

 

 

 

PS... Been asked and answered before. There's tons of threads about engine part combinations... so ya know, feel free to search.

[mikeatrpi]

Yes, I've searched and continue to do so. Got a thread in the tool shed as a reminder too.

 

I'm finding the archives to be full of conflicting information and a lot of folks saying "search" so I was hoping to find someone who had attempted this.

 

The turbo P90 head has better flow characteristics on the exhaust side than the P79. I found one post with someone saying they "didn't think" a turbo manifold would bolt up, with many other posts implying it wasn't an issue. I cannot determine at what power levels the flow characteristics of the P79 versus P90 will impede performance noticeably.

 

I've learned that swapping pistons means I'll need new bearings and to have the block checked. Have the crank turned. I've found people who have gotten away without some or all of this in the archives. Not many long term results posted in the archives however.

 

I have found people who have installed a turbo onto the NA block, and even used the NA electronics. I can't tell how satisfied they are with their decisions, or how long the motors have lasted, or knowing know what they do now if they'd do it that way again. Can't find that in the archives. And I've read about relocating the PCV on the intake manifold, and about tapping the oil pan for a drain fitting.

 

Thank you for the response. Maybe someone who searches weeks / years from now will find some of this useful.

[Kash]

You will be better off keeping the flat tops and running the boost at or below 10psi with the correct fuel/ timining map.

[RTz]

Is it feasible to install dished turbo pistons in an F54 block and use a P79 head with a turbo exhaust manifold? Or am I better off running the flat tops and lower boost?

 

Depends on what you want. If response and fuel efficiency are more important than an impressive dyno sheet (especially if only for 'bursts' of power), then I might lean towards a higher CR.

 

 

...and even used the NA electronics. I can't tell how satisfied they are with their decisions, or how long the motors have lasted, or knowing know what they do now if they'd do it that way again. Can't find that in the archives.

 

I know a gentleman, in a stock bodied Z, thats run well beyond 200mph (documented) with something similar to what you describe. He understood what he was doing. I've also done it, although not on that level. Would I do it again? Heck no... its a pain in the backside.

[mikeatrpi]

Thanks Ken + Ron. If you can't tell I'm evaluating adding a turbo to my NA engine, or just doing the full swap with a donor car.

 

Based on your advice, the decision really is NA engine with flat tops and megasquirt versus a full turbo engine swap.

[nismopick]

Based on your advice, the decision really is NA engine with flat tops and megasquirt versus a full turbo engine swap.

 

That depends on availability of turbo parts. Do you want to spend a lot of time and money buying each part you need, or just find a complete turbo motor w/ all needed parts? You can build a good flat top turbo motor, but like Ron just said:

 

Depends on what you want. If response and fuel efficiency are more important than an impressive dyno sheet (especially if only for 'bursts' of power), then I might lean towards a higher CR.

 

Building a lower compression motor allows for more power at full boost... high compression allows for quicker response.

 

If you want a monster motor, build a flat top turbo, studs all around, metal head gasket, head and valve work, strengthened rods, hybrid turbocharger... etc etc etc. You should also read these 2 books before starting:

 

 

[m1ghtymaxXx]

Well i'll be attempting a flattop turbo build this winter. Well not so much a build. I have a rusted out 83 turbo, and a clean 83 N/A, both with relatively low mileage at 152XXX kms each. I sandwiching the n/a shortblock between the p90a head and turbo oil pan, with all the other turbo goodies along with a fmic, z31 ecu/maf, bigger injectors and ka24 throttlebody.

 

The car will be built as a summer daily drive and a weekend auto-x rig, that should also embarass most of what i encounter on the street.

 

Nismopick: I though the oem flattop pistons where the weak link in boosting a NA block? Wouldn't a set of a/m forged pistons be a pretty good substitute for that expensive list of parts in your post?

[nismopick]

Nismopick: I though the oem flattop pistons where the weak link in boosting a NA block? Wouldn't a set of a/m forged pistons be a pretty good substitute for that expensive list of parts in your post?

 

Addition yes, substitute no.

 

Being cheap = future problems / headaches.

[mikeatrpi]

nismo thanks for the tips. BTW I recognize you from zdriver.

 

maxxxxxxx I'm going to remember your username. Perhaps we can watch each other's builds since it seems like we have similar goals. Just don't hold your breath for me... I move s l o w...

[X64v]

For what it's worth, I run a turbo on an L24 with an 8.8:1 compression ratio. Original flattop pistons and e88 head. I just megasquirted the engine first, got that running well N/A, and then bolted on the turbo (with all the additional stuff like oil return bung, etc). It really wasn't very hard or very expensive at all. I've got all the responsiveness of the stock motor off boost, with the power on boost. I'm running 9psi at the moment with no problems.

 

As for cost, the biggest cost to me was megasquirt, but that's only because i needed injectors and the manifold and all that, because the car was carb'd. The actual turbo swap cost me no more than about $250. Sometimes you can find donor 280zxt's for $300 or $400, but I had no way to transport or store a non-running car, and didn't need most of the parts off it anyways.

[m1ghtymaxXx]

For what it's worth, I run a turbo on an L24 with an 8.8:1 compression ratio. Original flattop pistons and e88 head. I just megasquirted the engine first, got that running well N/A, and then bolted on the turbo (with all the additional stuff like oil return bung, etc). It really wasn't very hard or very expensive at all. I've got all the responsiveness of the stock motor off boost, with the power on boost. I'm running 9psi at the moment with no problems.

 

As for cost, the biggest cost to me was megasquirt, but that's only because i needed injectors and the manifold and all that, because the car was carb'd. The actual turbo swap cost me no more than about $250. Sometimes you can find donor 280zxt's for $300 or $400, but I had no way to transport or store a non-running car, and didn't need most of the parts off it anyways.

 

 

Are you intercooled?

[TrumpetRhapsody]

Yeah, intercooled? and what do you estimate your whp to be?

[mikeatrpi]

Very good info, X64. May I ask if you're running NA, Turbo, or "other" injectors? And the turbo - a stock T3 unit? Was it rebuilt?

[Pyro]

I have have experience with the the combos you described.

 

flat top l28 with p79. good off boost response but had detonation problems over 8 psi and only could take 15 to 17 degrees of total timing while on boost. Much faster than a stock non-turbo. worth the install.

 

dished pistons with P79. a little sluggish off boost but with a stock turbo boost comes on quickly. ran good with 12 to 14 psi of boost but tended to detonate after that. could run about 20-22 degrees of total timing. Much much faster than the flat top low boost engine.

 

dished pistons and p90 head. Also a little sluggish off boost but with a stock turbo boost comes on quickly. Ran good with 15 psi of boost (about max for a stock turbo). Could run 24-26 degrees of total timing. Hard to hear detonation with this combo but you could feel it in the engine. A little faster than the P79/dished combo due to more timing.

 

Cork bell's book would recommend using the lower compression ratio.

 

All these combos were used with the stock ecu and fmu's for fuel enrichment. The mechanical advance were either locked out or reduced. I'm sure much better results would be had with an aftermarket efi system with ignition timing control.

[X64v]

I'm not intercooled at the moment, no. I do plan to be eventually, but with school getting busy I just don't have time.

 

I'm running 338cc Ford CFI injectors. Some info about them can be found in the sticky at the top of the fuel delivery forum.

 

I've been running 24-25 degrees of timing at 7psi for a good few months now. 22 degrees seems to be fine at 9psi. I give thanks to Clifton for helping me with my timing maps, I didn't really come up with those numbers on my own. This weekend I'm going to tune a little more and set things around 20-21 degrees at 10psi. If you're wondering how I'm controlling spark, I'm running MSnS-E as in my sig, triggering via an '82 N/A VR dizzy, with mech. and vac. advances welded up tight. Oh, all this on 91 pump gas.

 

It's a stock 280zxt T3. I have not rebuilt it. I was told it has about 100k miles on it when I bought it. I've put about 5k miles on it No axial play and just a little radial.

 

My best guesses for whp are 160-170 @7psi, perhaps 180 or so at 10psi. Not staggering numbers, but keep in mind I'm almost half a liter down, and it's a bone stock l24 longblock. And those are guesses, I could be waayy off.

 

Any other questions about my set up, timing and fuel maps, whatever, ask and ye shall receive.

[mikeatrpi]

Thanks guys for the tips!

 

I need to do some research on MSnS triggering off an 82 n/a distributor... I thought you needed an 83 with a CAS for that. I had budgeted $50 for a junkyard EDIS setup.

[X64v]

Nope, there isn't really any specific one you need, there are many, many possible ways to trigger MSnS-E. If you've already budgeted for EDIS, do it. I just used the VR dizzy because I had one already, so it was free. I'll be upgrading to EDIS eventually, when I get a chance.

[usafdarkhorse]

Wow...after doing a search, this thread became very helpful in determining which way I should go in my quest for N/A to turbo.

 

I have a '76 Z with an '83 F54/P79 swap and I was concerned about detonation with the flattop pistons and the load on the ECU.

 

Now, having read all of this, I'm really wanting to get this rolling.

 

However, I'm at a loss to know what I need or what I should be on the lookout for. Manifolds? Oil pumps?

What sort of things would be REQUIRED for those of you who have made the jump from N/A F54/P79 to turbo? I have the FSM for the '82 280ZXT but I'm a little confused on which parts I need to complete it.

 

Thanks,

 

Jared

[mikeatrpi]

I haven't done it yet, so caveat emptor -

 

turbo exhaust manifold and turbo are the essentials

 

you'll need to plumb an oil feed line - usually a Tee off the pressure sending unit.

 

oil drain line - tap the oil pan (people weld bungs, or JB-weld them)

 

from the exhaust standpoint, you can either use the stock downpipe, or build your own. I imagine there will still need to be some custom exhaust work even with the stock downpipe.

 

charge side - either use a stock turbo J pipe (compressor to throttle body), or you can plumb in an intercooler. Based on personal experience by contributors in this thread, looks like J pipe is do-able.

 

then for the intake - depends if you want to keep the stock ECU if you keep the air flow sensor.

 

Oh, and I believe you have to relocate the PCV on the bottom of the intake manifold so it clears the turbo.

 

A question you might also ask- does the 83 NA distributor have the crank angle sensor like the 83 turbo's? Those are supposed to be super-simple to interface to megasquirt.

 

Does anyone care to correct me? (please?)

 

Edit - I forgot - fuel... bigger injectors are a must, yes?