HY35

[gmorrone1214]

Hello everyone, I know I will probobly get flammed for this but I was wondering what supporting mods I would need for the zx while running a hy35. I am looking for moderate 300-350hp.

 

Engine

My 81zx is NA , so it has the flat tops and higher compression. Would running just the 2mm thicker head gasket suffice.

 

Fuel

 

Merkur XR4TI / Ford SVO -  

---Would these suffice or bigger injectors needed?

 

---New Fuel pump Walbro 255

 

Management

 

---Was going to go with Mega Squirt , If I do what is needed from the ZXT engine, anything?

 

Wastegate

 

---Running external, mounted on exhaust manifold. 

 

Intercooler

 

---Was thinking maybe a dodge srt4 neon intercooler , stock unit is good to 350-400 hp.

 

 

What do you all think? Any suggestions or additions?

 

[seattlejester]

2mm head gasket would be a start, ARP studs would probably be a good idea while you are in there. Also keep in mind using a thicker head not only means increasing your deck height but also shortening the chain tension by 4mm as well. You can get away with high compression engines nowadays with modern ECU systems and good tuning, less room for error. You will need to find a source for oil for the turbo and a port to dump oil back into the motor.

 

Fuel:

Do a bit more research for the lazy among us, what is the flow? A real general rule would be a cc/min = hp in a 3L 6 cylinder using gas. 

You should probably consider fuel lines as well.

 

Management:

Megasquirt is going to need a TPS signal which the ZX does not have, you can reuse the coolant temp sensor or use the supplied one, IAT sensor will be needed, a port for the MAP sensor. You will need some kind of spark trigger signal. Whether that is a HES or VR sensor triggered by a trigger wheel or an optical sensor in the distributor will be up to you.

 

Wastegate:

Good for you? Make sure it is big enough to bleed enough exhaust to keep your boost low. Also keep in mind size takes a hit with priority. The stock manifold does not have anywhere to mount one and welding to cast is a real hard task.

 

Intercooler:

Standard go to was the Isuzu NPR one. Really any decent sized one with your desired orientation and outlet size will be good. You want at least 2.5 inch pipes if you don't want to come against aerodynamic drag if I remember the term correctly.

 

Keep in mind your transmission may not be happy with what you are planning. Neither will your brakes, and neither will your axles. 

 

If you know you are going to get flamed do some more searching, the only reason people complain is when the post really shows a lack of searching whether that means not spending the 20 seconds it takes to do a google search and scan through the hits or taking a gander at the FAQs or a quick glance in the last couple pages to see if something similar has come up.

 

Hope that helps

[lowrider]

Hello everyone, I know I will probobly get flammed for this but I was wondering what supporting mods I would need for the zx while running a hy35. I am looking for moderate 300-350hp.

 

Engine

My 81zx is NA , so it has the flat tops and higher compression. Would running just the 2mm thicker head gasket suffice.

 

The 2mm head gasket should be fine. I ran an F54 flat top block and a P79 head with my HX35 several years ago with the motor completely stock. My suggestion is to ditch the P79 for a P90. I say this because the P79 has liners in the exhaust that heat up cherry red to remove emissions. I had one of the liners break and wedge in the exhaust wheel of the turbo before I put the HX35 on. Fortunately for me, it was close to idle when it happened and the turbo wasn't spinning very fast and didn't wreck the exhaust wheel.

 

Fuel

 

Merkur XR4TI / Ford SVO -  

---Would these suffice or bigger injectors needed?

 

After some research, the XR4TI injectors are 35 lb/hr, I would go with something like 42 lb/hr. The Merkur injectors are going to be close to 100% duty cycle at 350 horse power.

 

---New Fuel pump Walbro 255

 

The Walbro should get the job done.

 

Management

 

---Was going to go with Mega Squirt , If I do what is needed from the ZXT engine, anything?

 

Seattlejester nailed it.

 

Wastegate

 

---Running external, mounted on exhaust manifold. 

 

I currently have my HX35 setup this way. The manifold is cast, but it is cast steel which is makes it easier to weld versus cast iron. I popped a hole directly below the flange on the exhaust manifold and welded on a sch40 90 weld elbow with the wastegate flange. I also went with a large 44mm wastegate to be able to run lower boost levels without creep.

 

Intercooler

 

---Was thinking maybe a dodge srt4 neon intercooler , stock unit is good to 350-400 hp.

Again,  Seattlejester nailed it.

 

What do you all think? Any suggestions or additions?

 

I would suggest investing in a good wideband O2  if you don't already have one. They are an incredible tool when tuning and when diagnosing problems if they were to arise.

With 300-350 horses your going to need to address your clutch, the stock clutch and pressure plate aren't going to cut it. You could either upgrade the clutch disk and pressure plate for the 225mm flywheel you have, or you can upgrade to a flywheel and clutch setup with more contact area. There are a few options of the latter around including the 240mm zxt / 2+2 flywheel and i believe someone makes a spacer to allow the use of an RB flywheel.

 

The trans should live for a while (I got close to 5 years out of my 83 zx trans) but I would be looking for a beefier solution in the future.

 

That's about it off of the top of my head, if I remember anything else I will be sure to post it.

Edited July 28, 2017 by lowrider

[elishallen]

You can get by without the TPS. I ran my megasquirt without one until just recently. It really helps for datalogging and flood clear.

 

Edit: Oh and the accel enrichment.

Edited August 15, 2017 by elishallen

[seattlejester]

^True, but the accel enrichment is going to suffer a bit.

 

You have to run MAP DOT instead of TPS DOT if you don't have a TPS and only have the TP Switch of the zx. MAP DOT is slower to respond so accel enrichment will take a pretty big hit in drivability, although it isn't impossible to tune for by any means. You can also tune TPS DOT sitting still technically without the engine running really. MAP DOT will have to be adjusted in real world situations and can vary depending on things like load which will be affected by things like grade and how much you slip the clutch. 

[gmorrone1214]

Thanks for the help! Also would I be able to run the stock na distributor, or will i have to run the zx? I see a lot of talk about locking the NA distributor, I believe this is to tune with the megasquirt? Therefore I should  be able to use the stock dizzy and just lock it and run the turbo?

[seattlejester]

Kind of a bad omen if you are asking that. Kind of like when a kid stares at a power outlet for a long time and asks you for a fork.

 

An NA distributor has no electronic control if I'm not mistaken. Locking the NA distributor is a thing people used to do when timing control strategies were expensive or inapplicable. You set it to a value via a timing light and disable any manipulation strategies whether the springs or the pressure assist. Usually done by cementing the mechanism or jamming it to prevent it from working. Depending on what you set it at though you would either have a poorly running car at idle or a poorly running car up top (poorly running at top could be catastrophic). I think the most basic megasquirt units will do spark control via EDIS, so that is kind of a thing of the past. I think the only people that still do things like that are lemons racers who cannot spare the expense from the JY.

[ZHoob2004]

You want to lock the distributor if you are using some form of electronic timing control, such as a megasquirt. You can run megasquirt with a single coil and a distributor, much like the stock system. In this configuration, you would disable the mechanical and vacuum advance on the distributor to not change your timing since it is being controlled by the megasquirt instead.

 

Later distributor motors, such as the Honda motors I'm most familiar with, do not have any vacuum or mechanical advance because it's all controlled by the ECU.

[SleeperZ]

There is a reason the L28ET distributor has a larger diameter cap, which is to allow a wider range of spark advance.  I don't think you can reliably get that with a locked N/A distributor.

 

In regard to the SVO injectors, they flow 370cc/min, which does support about 300hp.  I dynoed an altitude-adjusted 313hp to the wheels with those injectors, but for reliability I think you should use a higher flow unit for 300-350hp.

[Metro]

I used a welded VR distributor for many years on my L28et. I had to adjust the internal plate all one way and use a low trigger angle of around 17 degrees (which puts MS into next cylinder mode).

 

But SleeperZ is right, you'll want to make sure the spark is going to the correct post at all ranges of advance. I just set mine up so that it's pointing at the middle of the post and that seemed to work fine.

[gmorrone1214]

There is a reason the L28ET distributor has a larger diameter cap, which is to allow a wider range of spark advance.  I don't think you can reliably get that with a locked N/A distributor.

 

In regard to the SVO injectors, they flow 370cc/min, which does support about 300hp.  I dynoed an altitude-adjusted 313hp to the wheels with those injectors, but for reliability I think you should use a higher flow unit for 300-350hp.

 

Yeah I was thinking of going with the 440cc supra injectors since you seattlejester stated the SVO would be near max and pushing the limits. So it would have to be turbo dizzy then?

[seattlejester]

I didn't really say anything about fuel.

 

It doesn't have to be, but a turbo dizzy would be easier to setup and allow for a bit more adjustment especially if it is the optical one that you just plop the DIY optical wheel into. You could go EDIS with a trigger wheel on the crank which doesn't require a distributor, you can go COP's which also don't require a distributor. 

[gmorrone1214]

Can I use the TPS  on the s13 throttle body? Or is the TPS pic I posted by itself the only usable one?

 

 

 

 

 

 

 

[seattlejester]

The 240sx throttle body is a pretty common swap so I imagine so. The 3 pins are a pretty good sign. You can find out with a multimeter if you have a power supply, set it to volts and supply power and ground the ground appropriately and see if the third pin outputs at a range (from 0-5v most likely) as you play with the throttle blade. Or you could do the same with the multimeter with the ohm setting I think, resistance is always something I need to review before use, but I believe you should see a varying value with one of the pins when referenced to I think the power pin or the ground pin. Or...that might not matter which pin you reference as long as you read a resistance change as long as it includes the output pin.

[gmorrone1214]

Just ran into a clearance problem that I do not see addressed in other forums.  The way the steering is set up (outlined in red) there is no way that I can fit this hy35 holset in there. 

 

 

Is the swap that I need manual rack and pinion to make this fit? Did not think this was going to be a problem with the swap ugh 😤