'82 280zx Turbo max boost without an intercooler

[cpan]

Hello All,

 

I have searched far and wide and cannot seem to get a good answer to this question.  I am about to pull the trigger on a Megasquirt 2 v3.57 with electronic boost controller.  I started going down the rabbit hole of upgrading the fuel rail and adding an intercooler but I think I would just like to keep her as stock as possible and just upgrading the ECU.

 

That said, if I just upgrade the ECU with this Megasquirt kit, what amount of boost can I run without any other upgrades, mainly an intercooler.  I understand that at about 12psi I'm hitting the limit of the turbo, injectors, and getting to the danger zone of detonation?

 

Does anyone have any experience running 8, 9, 10psi without an intercooler?

 

Apologies again if I have missed an easily searchable topic.

 

Best,

cpan

[AydinZ71]

You will make more power for the same boost with an IC. I wouldn’t go past 10psi without an IC. You shouldn’t detonate with such a low static CR (7.4:1), but your cylinder temperatures will be high and your rings will not last as long. 

Edited May 5, 2022 by AydinZ71

[cpan]

7 hours ago, AydinZ71 said:

You will make more power for the same boost with an IC. I wouldn’t go past 10psi without an IC. You shouldn’t detonate with such a low static CR (7.4:1), but your cylinder temperatures will be high and your rings will not last as long. 

OK.  I am not opposed to putting an IC in but the best options I found (kits that are ready to drop in) require the removal of the engine fan and clutch with an addition of an electric fan on the radiator to make room for piping and the removal of the carbon canister.  I am not concerned with emissions as the car is considered a classic in New York State and will not need to pass emissions for inspection.

 

Kits I am referring to:

https://www.cxracing.com/intercooler-kit-nissan-datsun-280zx-s130/KIT-L28ET-280ZX-IC0029-25  (this one comes with a blow off valve)

 

https://www.godzillaraceworks.com/turbo/datsunfmic  (no blow off valve)

 

Questions:

Do you (or anyone) know of any IC kits that do not require the removal of fan/clutch, carbon canister?  I am not into sourcing old IC's off other cars or custom bending pipes.  Looking for easy installation solutions.

 

Can anyone point me to a post/article on how to do the removal of the carbon canister?  This is another area that I have not found any good resources on.

 

This is how the rabbit hole starts.  Now I'm thinking if I'm going this far, do I upgrade the fuel rail and injectors...  I guess I wouldn't need to unless I plan to go over 12-14psi (which I don't)?

 

Thanks again!

[AydinZ71]

Sorry friend, I’m an S30 guy so not familiar with bolt-on anything for an S130. 
 

I could help you with a custom solution that is specific for an L28et, but not specific to an S130 chassis.  
 

it is a slippery slope, like you said. The long block can reliably handle 300-400hp, but any solution will require you to do some minor fab work. Even an aftermarket Plug-and-play EFI will require you to mount the electronics somewhere and do some wiring. 
 

If you don’t have the confidence to relocate or remove the carbon canister, I suggest keeping it at or below 8psi or paying a tuner. There are lots of little problems here and there that need solving once you start down this path, and it may be quite stressful if you don’t have the mechanical experience or not willing to garage the car for several months while you work out the kinks and learn. 
 

In general, getting an IC and upping the boost until you (safely) max the OEM EFI/injectors is your best bet. Beyond that, you really need to do a lot more work. 

[Dat73z]

Depending on how much you care, if you get the CX kit you may need to modify the brackets. I thought the brackets would save me time but they didn't fit the s30 chassis well at all so I ended up tig welding and reshaping them a bit then making new holes. I should've just made them from scratch because I probably spent a few hours and $10 of welding gas just redoing them alone. Maybe they'll fit the s130 a bit better

 

I know GRW works on s130s and are fairly knowledgeable/helpful so I'd give them a call and ask your Qs. They'd be able to let you know how well their in-house intercooler/bracket kit would work on the s130 as well

[cpan]

Thanks!

 

I was looking at the GRW kit (obviously where I ordered my MS kit from) but was turned off that it did not include a bov.  For now I am going to just get the MS kit installed and get her running right and then explore IC kits.

 

Appreciate all the feedback!

[Dat73z]

Yeah I'm sure if you called GRW and asked them or incorporate a BOV they would be more than happy to accommodate. They do all sorts of builds and fab work

[tjharri1]

I am in the same boat as @cpan

other than my z is a 1983.

 

my dad has owned this car since 1987 and was my first car when I was 16. I am taking possession of the car this week. It has ~85k miles on it and is mostly restored. I am not interested in an engine swap but would like to upgrade the turbo for more power.  Given that it is a factory turbo, I was hoping that it would be relatively easy compared to other projects...I turbo'd my 1988 BMW 325ix that included injectors, an intercooler, megasquirt etc.  From the sounds of it, doing something similar to the 280 is actually harder.  That said, I'm still headed down that path.  Just looking for the best place to start.  I would appreciate any guidance.

 

 

280zx idle 5-28-2022.MOV

Edited May 30, 2022 by tjharri1

[Gollum]

First thing to set straight here is that lack of IC might lead to being harder on piston rings. This simply isn't true. Yes heat is what will kill your rings, and without enough ring gap then heating up the rings enough to the point of them touching will crack a ring land on the piston, just about every time (true for all engines, not just L engines).

 

But that will be caused by BMEP over time far more than inlet temps. Heat produced is going to be a product of how much fuel is burned. Cold air makes for denser air makes for more fuel makes for more heat generation. An extra 3psi of air (at valve) will cause far more BMEP than 50 extra degrees fahrenheit on the inlet air.

 

All THAT said the largest problem with hot air and raising the boost to the limits of the factory turbo, is that you WILL be seeing inlet temps over 200 degrees (been there, done it). At those temps your MBT or required timing is going to be a VERY narrow window. Retard the timing to be "safe" you'll be leaving a lot of power on the table. Be too aggressive and detonation is almost guaranteed since the mixture is so volatile. The factory compression is low, but the head is also super inefficient at mixing the charge, so you'll be bound to have rich and lean spots within each chamber, and running under load with that hot of air long enough, get heat soaked into that head and it will be detonation prone.

 

 

So, if you want to spend a full day on a dyno with someone who knows what they're doing, you can likely get well over 200whp without an intercooler. But the tuning would have to be exact, and you'll only see that power figure on a cold run. If it's tuned well then each sequential run as it gets hotter and hotter the peak power will go down as inlet temps rise.

 

Run an intercooler, or run E85. Or run both. Both take work. And if you want "bolt on" parts, I hate to say it: buy a different car. Any car that's outside of mainstream is going to take a good bit of work to modify. Personally, I'd go with a generic intercooler and generic piping kit. Get a larger same side in/out to make routing easier inside the engine bay, and while you're at it make sure the inlet to the turbo is in front of the radiator outside the engine bay like factory. It's worth it. If you upgrade your rubber fuel lines, injectors and pump to run E85 you'll have all the cooling you'll need to reach the limits of the factory bottom end if you put enough turbo on it.

 

Hope that helps.

Edited November 21, 2023 by Gollum

[Brad-ManQ45]

If you get a bigger turbo you won't heat the air as much as the small one.  I ran an S3 trim turbo to 14 psi with no problems stock - but I limited my rpms to about 4500 at that boost.

[AydinZ71]

Hmmm… not too sure it’s as simple as a smaller turbo heating the air more than a larger turbo. The efficiency of the turbo for a given flowrate and pressure will have some influence, but nearly all of the temperature rise is purely a thermodynamic phenomenon. See attached graph. Pressure and temperature are inextricably linked. 
 

You are correct if you mean putting in more work (for the same pressure and flow) will heat up the air more. I just think it’s small compared to the predictable temperature rise caused by compressing air regardless of efficiency. 
 

As for intercoolers, the only reason they did not come stock was to save cost, and the boost was so little that there wasn't enough of a difference in temperature to make it worthwhile. I’m not aware of any mass produced vehicles today with double digit boost that does not include an IC from the factory.  It adds efficiency, power (for a given boost), and allows for more ignition advance with less chance of detonation. It’s all upside, and it’s just plumbing and a heat exchanger. 

 

 

[AydinZ71]

@Gollum

Two identical engines. Same boost, let’s say 10psi. One with an IC, one without. All other variables equal. 
 

100% agree IC engine will make more torque, burn more fuel, and produce more total heat to the engine’s cooling system.

 

You believe the non-IC engine’s rings will wear less than the engine with the IC? 
 

Respectfully, I think we will have to agree to disagree. This has not been my experience. 

[Gollum]

@AydinZ71 And I'm perfectly content to agree to disagree. My experience and point is that HEAT is what destroys rings, and that inlet temperatures have almost zero bearing on heat produced in combustion.

 

The normal factory combustion within the engine at factory boost is going to be somewhere in the neighborhood of 800-1200C at point of ignition. Exhaust gasses once COOLED OFF during the power stroke will still be well over 400F at the manifold.

 

Being concerned about 100F inlet or 160F inlet is irrelevant compared to these temperatures. That's my point.

 

Now, if your lack of IC is causing you to be on the edge of detonation and getting into some sporadic light detonation here and there, I can see that eating through rings quickly too.

 

The guys out there running 2k+HP on meth powered big blocks still chew through rings like a consumable, and their inlet temps at the valve itself are likely well below ambient. Inlet temps are only a small fraction of overall heat generated within the chamber and thus expanding the rings and causing them to work.

[AydinZ71]

@Gollum I think that’s exactly it, thanks for touching on it. It appeared to me to be very difficult to maintain a consistently detonation-free combustion with higher intake manifold temps. The misconception I had before gaining first-hand experience was, I would “hear” detonation. In practice, light detonation was inconsistent and not noticeable when running no IC. The peak temperature experienced in the cylinders would skyrocket unpredictably (obviously more on warmer days), whereby that extra 60 degrees would accelerate the combustion significantly and make it difficult to control with set ignition timing. Combine that with with OEM pistons/rings, and the rings would start seeing significant blow-by after just six months. 

 

closed loop feedback with knock detection may be a solution but I can’t say I have enough experience to know for certain. Retarding timing and dumping more fuel when knock is detected could solve it, but without forged pistons or a lower ring landings, there just wasn’t much room for error. 
 

So what I’m really saying is, I found it hard to control and over time the rings just wore out. Once an IC was added, the motor became more forgiving. 
 

Nissan’s 7.4:1 CR and single digit boost was a very conservative to be certain, and I was pushing that envelope. 
 

your other points on heat are well taken. I also agree the total heat (and pressure) in the cylinders does not automatically translate into unreasonable ring wear. It’s really peak temperature, such as from a lean mixture, detonation, or incorrect ignition timing. Naturally, the mechanical affect of knock are there too, which goes beyond simple accelerated wear and can do all the fun catastrophic stuff you mentioned such as cracked pistons, so-on. 
 

I guess the old adage is true… it’s all in the tune. 

Edited November 28, 2023 by AydinZ71

[Gollum]

I think a bit part of the problem with detonation on L heads is that the overall chamber is "lazy" compared to any modern chamber. There's virtually zero swirl going on. The spark plug is not ideally placed. The pistons aren't do anything to "help" either. Even if you used flap top pistons for added quench, you're still just putting band aids on upstream problems.

 

And I'm not knocking 2V head designs. But look at how far GM has come:

 

That chamber is just cleaned up, not worked. Note the plug angle. Note that it's quenching on both sides and that they're "pointing" different directions. There's also very little valve shrouding.

 

Also, find me an EFI engine designed from scratch in the last 3 decades with round intake ports (to a single valve). Also, what are the average valve angles?

 

Nissan more than once chose valve angles wider than they should have, and only realized it in hindsight. And engines like the L series which were initially carbureted and converted to EFI suffer from old assumptions. By using oval or other elongated entries you're encouraging the airflow to maintain better velocity averages across the lift and RPM range, and promotes swirl to excite atomization.

 

Injectors are also worlds better than they used to be. If you pay attention, most people who de-cap injectors to get more flow might be able to make more power, but idle and cruise quality suffers.

 

Ben talked about some great stuff in this podcast, and it's well worth the listen:

https://www.hpacademy.com/blog/089-pushing-the-limits-of-nissans-forgotten-turbo-4-cylinder-podcast/

 

But something to ponder that he brings up, is that on meth they were running down to lamba 0.50 in order to keep the engine from detonating, that's gasoline equivalent of 7.3:1 btw... Absolutely insane amounts of fuel, and adding intercooling capacity wasn't helpful, and in some cases detrimental as they had an _even harder time_ atomizing fuel when there was less heat in the charge. And this is with the measurably better FJ head which had a lot more Nissan engineering prowess behind it's inception.

 

So to think we're going to magically get a L series head to not fight detonation with some magic bullet? Nope. It's the reality we live with. We can do what we can to make the results predictable and live within those confines. I would say definitely add a huge intercooler, as a rule. If you're going to push past the 300whp mark, definitely do the head cooling mod. If you've ever got the head off, do Jeff's block/head cooling upgrades and use his head gasket. If I was still playing with L engines, I would also definitely go with an electric water pump, and probably reverse flow the engine. I would also never run non-premium pump gas, and ideally would just run E85 all the time. I had a MN47 with the intentions of making "high compression" turbo engine and doing all the above and more. But time and life lead me down different paths.

 

The L engine can do amazing things if you put in the time and energy. But in a factory arrangement, you're almost always going to be fighting detonation as you raise the boost.

 

Also, side note. I'd ditch the distributor/dizzy as anything other than an oil pump and potentially a cam sync. Put a wheel directly on the crank and you'll get FAR better timing accuracy. Even if your shaft has near-perfect lash (which any old used shaft won't) then you still have shaft flex/vibration issues to deal with, and your timing could be as much as 3 degrees off just from deflection. In my case with the added lash I was getting as much as a 8 degree timing error. Great way to grenade an engine.

Edited November 28, 2023 by Gollum