Piston/ECM Decision Time. Suggestions?

[Jersey]

Hey all. Hope everyone's doing well. So, here goes... my cousin blew another piston (ring glands) and we're starting the rebuild process and was hoping for some advice. I'll list what he's running first.

 

78 280 w/83ZXT motor, P90a hydraulic head, stock bore, stock cast pistons

T3/T4 50trim E wheel, .63 Stage III clipped, oil & water, bullet nosed, ported WG hole

SVO 370cc injectors

60mm 240sx TB - Ported Intake to match

GReddy BOV & Boost controller

Stock 83ZXT ECM

Stock AFM

Stock narrow band O2

MSD Fuel Pressure Regulator w/boost reference

Custom Fuel Rail

MSD 6a

'82 NA 5sp Tranny

Walbro GLS-392 Fuel Pump

3.90 LSD w/CV's

Large NPR intercooler

3" full mandrel exhaust/custom downpipe

ACT HD Clutch/PP 240mm

 

Just figured i'd list it all, or at least what i can remember at this point. lol.

 

Our initial thought was to go with forged pistons since this is the second time (different cylinders) he's blown the glands apart. Here's what i'm thinking now - Save some $ going forged and replace the blown piston with another stock one or go with hypereutectic pistons - which i dont know a thing about, then spend the savings on an aftermarket ECM (MS, Haltec...) to get the A/F & timing values correct (safe) through the full RPM range. I'm sure he's running rich down low with the MSD FPR to compensate when in high boost situations but i'm sure it's probably still running lean on top, pre-igniting and causing the damage. Who knows, maybe the 370cc injectors are too small for that T3/T4 - i just have no way to monitor at this point. All the cylinder walls still look good with original cross hatchings and spec out fine so no work to be done there.

 

So i guess my question boils down too - whats your piston & ECM suggestions?

 

Any additional comments/opinions are welcome as well. I'm a big boy, i can take the flames if and probably necessary. lol.

 

Thanks in advance guys,

Jersey

[infiltrate2000]

I run 18 psi on a 50 trim z also, stock l28et internals. Car has tecII standalone. I say instead of going forged piston, get a standalone. Stock efi is garbage, my friend blew a ring land also on a motor with stock turbo that was only on 7-8 psi of boost. We are currently throwing in a early l28 NA engine (read & learn from TonyD) and running 300zx ecu and maf with nistune. Ironic, his setup is simlar to the one you list, but he was on stock turbo.

Get a better spark/fuel managment and use stock piston. Heck, we are going with a NA motor on my friend car but with some way of tuning.

Edited November 28, 2012 by infiltrate2000

[evildky]

I'll tell you that that turbo will support a lot more power than those 370cc injectors. I also didn't see mantion of arp headstuds or metal hg but if you're breaking ring lands I suspect they've been upgraded.

 

If you're breaking ring lands it's a timing, heat or lean issue, forged pistons are always a good idea but you need to get the car on a dyno or upgrade to managment with datalogging so you can figure out which of these issues is the culprit.

[Bernardd]

The stock bottom end will handle that turbo, go with the tuneable efi.

[Tony D]

I would stick to stock AND stock head gasket... You are detonating regularly enough to break pistons, forged will only make the next failure more expensive.

 

Till you are running 400+ HP and have a cam capable of over 7,000 rpms, stick with the stock bottom end. Even with that I'd tune to 7,000, then 7,200 or maybe 7,400 before putting in the forged slugs to tune above to power peak of the cam.

 

Buy a detonation stethoscope like from Speed EFI in Australia, uses VW piezo knock sensors as microphones coupled with a headphone set. You will hear detonation when you never considered there was a problem!

 

And that will convince you to run a standalone...

[Gollum]

Is there an echo in here?

 

Get a standalone...

 

 

Echo... Echo.... Echo...

 

Yea, here's my notes on the list:

 

78 280 w/83ZXT motor, P90a hydraulic head, stock bore, stock cast piston

Will make 400hp with ease. Hydraulic lifters should be in worker order though. They're fine if they are, but a bad lifer is no fun.

T3/T4 50trim E wheel, .63 Stage III clipped, oil & water, bullet nosed, ported WG hole

This is what everything should be built around. It's one of your systems most central pieces. It's like the head in a NA build... Everything should match THIS component.

SVO 370cc injectors

More than enough, and since you're running stock EFI this is just a nasty solution. Really should be running STOCK injectors with just a GOOD RRFPR that can adjust the RATIO of how much pressure it's adding per PSI... and that's only IF you're trying to get the stock EFI to live which most people should give up on unless they're proving a point.

60mm 240sx TB - Ported Intake to match

Totally unneeded, only reason I see to do it is because it makes for a clean conversion to a REAL TPS(ensor) needed for MS

GReddy BOV & Boost controller

I'm not a fan on electronic boost controllers, especially for lower HP turbo motors like this. And the BOV should be recirculating type. Otherwise you're just asking for problems. And if you're smart you should be running it as short of piping as possible and running it into the turbo inlet at about a 45 degree angle. This will help keep the turbo spooled and your air metered correctly. You want to sound like rice? You'll blow up like rice.

Stock 83ZXT ECM

Main issue... RED FLAG

Stock AFM

Biggest flow restriction! This almost makes me laugh at the 60mm TB

Stock narrow band O2

Not a problem really as long as there's a wideband when you're actually trying to tune the sucker. And post CAT widebands are almost pointless when trying to get into the nitty gritty details of a tune.

MSD Fuel Pressure Regulator w/boost reference

Worthless if you haven't checked ratio controls with a wideband. Might as well be trying to shoot a zombie attacking your kin in Alaska while standing in New York with a rocket launcher.

Custom Fuel Rail

Not even needed, and almost pointless. If you haven't you should consider a twin inlet design like stock. Helps reduce flow pulsing from the injectors opening and closing. Unless you double the diameter of stock you're most likely causing WORSE flow to the injectors when comparing how evenly they're supplied.

MSD 6a

Meh, shouldn't be hurting

'82 NA 5sp Tranny

How's it holding up? Some break at 250hp, others at 500hp... go figure

Walbro GLS-392 Fuel Pump

I don't trust walbro's, but I'm paranoid.

3.90 LSD w/CV's

Who converted the 3.9? How much it cost you? (I'm wishing to do the same)

Large NPR intercooler

Good, but how well was it installed? Does it seal nicely to the radiator? It should. Do you not have any more than a .25" gap between any pipes or are you letting silicone couplers bridge the gaps? Get the transitions tight.

3" full mandrel exhaust/custom downpipe

Good, shouldn't cause you problems till you're well beyond the ability of the stock head/block combo

ACT HD Clutch/PP 240mm

Irrelevant but thank you for quality of details.

 

Hope that helps you out in your endeavors.

[Tony D]

Agreed.

 

I would say under 350HP a 225mm clutch with proper facing is suitable and helps revs from lower MOI. This may make it at 400.

I prefer 3.70 ratio with stock cam, it seems to work really well for the highway merge.

 

I like the two-stage TurboXS poppet boost controllers. After living for years with an EVC I realized I was running one of two boosts "Everyday" and "Bring it ON!" A flip switch keeps it under the hood close to the wastegate actuator, making for crisp controller action compared to long tubes used on most stuff with remote mounted solenoids and stuff like that.

 

The thing I'm not really cool about is the head and cam being left out. You can make 400HP on the stock hydraulic head (Steve 'Stealth' Webb was doing it 20 years ago!), but you are running up the pressure ratios like crazy and generating a lot of heat and thrust load on the turbo. If the head was ported like an N/A, and flowed 210-220 CFM the power you would make would be a such an exponentially lower pressure you could almost make 400HP without an intercooler (seriously!, 380Ft-Lbs at 4500 rpms and 8.39 psi of boost close enough????)

 

I would call this a typical "Maximum Boost" Style build, my preferences go toward flow more than pressure. As I've oft been heard to say "Boost is nothing more than restriction to flow." The lower boost you run, the lower fuel pressure you run, and the easier it is to get fuel pumps that aren't running off the high end of their curves at pressures above 5-6 bar. This allows you to "Tailor" the injectors sizing through tweaking fuel pressure higher or lower to get the pulsewidth you want for best idle and low-speed driveability. BTW, all EFI regulators are Manifold-Referenced meaning by default "Boost Referenced" -- you really don't want one that isn't, even on an N/A. Usually when people mention an FPR, its a non-linear (rising rate) style for more fueling at boost, which is why you run an EMS in the first place! I'd skip the 60mm T/B...but clean the inlet runners. An Extrude-Honed Stock Intake will flow about 190 CFM per runner. So getting your head to flow to AT LEAST that point would 'match the components', porting the head fully to the 210-220CFM range allows for a debottlenecking with ITB's or Lone-Wolf style intake later allowing more flow and the same boost...meaning more power without more heat and pressure.

 

Echo... Echo...Echo...Echo...

Edited December 1, 2012 by Tony D

[Gollum]

To play devil's advocate here to Tony's point of view (which I actually agree with, just saying this for the sake of saying it because apparently this has somehow sparked enough interest to keep me from bed even though I'm waking up in 5 hours...)..

 

... even though this might parallel the "maximum boost" style setup, EVERYONE pushing the limits will be running very absurd pressure levels. The guys making 1000+hp from 2 liter 4G63 motors certainly aren't pushing 8psi. Thus, one can deduce that there's nothing inherently "wrong" with trying to figure out how to cope with high boost levels and the evils that come with.

 

I think Tony's point, and the one that I agree with is that for what MOST of our power goals are around here, a little lesson from the NA crowd will go a LONG way and prevent MANY problems. Remember, you're killing your motors due to detonation, I'd guarantee it. Detonation is a product of HEAT first and foremost, NOT timing, NOT compression, NOT AFR. Even though each of those play a FACTOR in heat, HEAT is the ultimate enemy. Lower the pressure, lower the heat. PERIOD.

 

If you plan to shoot for a 1,000hp L motor, then by all means, learn to cope with high boost and the heat that ensues. But I darn guarantee you that you'll want some programmable EFI somewhere along the way. And in either setup, high boost levels, or low boost with high head flow, you're going to need a not-stock fuel and timing curve...

[Tony D]

Yep!

[Jersey]

Thanks a bunch guys for all the responces. Alot of info shared and appreciate it all. I love to learn and build knowledge. Attention from some of the big wigs huh? Ut oh... i'm in trouble. lol. Ok, so here's the route we decided to go as of yesterday morning.

 

Ordered a set of ITM standard size pistons/rings/rod bearings, ARP head bolts, Wideband O2.

 

We were also going to install a standalone (most likely MegaSquirt) at this time but figure we'd get it running like this first, on LOW boost, just to make sure everything's ok. Once it all checks out, install the MS & get this thing tuned correctly, or at least a sh*tload better than poking and hoping. We built it on the cheap without standalone and we all know that only lasts just so long before stuff starts breaking, which it has. I'm SURE it's running real rich down low and extremely lean up top creating massive heat, causing pre-ignition/detonation. The MS should put us on the right track and to also see if the 370's can supply enough fuel for this T3/T4.

 

Gollum - Thanks. To respond to some of your suggestions...

 

H-Lifters - all in good condition and working properly.

370's - Hoping they'll be enough once we go MS. We shall see. Suggestions on a good RRFRP? Not trying to prove a point, just didnt have the cashflow to go standalone during the initial build. Always costs more in the long run, huh? lol.

60mm TB - just one of those things. Was hoping for a lil quicker throttle responce, almost seems too much, very sensitive. Should be good once MS installed.

BOV & BC - BOV is recirculated toward turbo to help keep spool, short pipe. No rice here at age 45 & 50 but, we do enjoy eating rice! lol. The BC is a TurboXS, not electric type. Sorry fr the misinfo.

Stock ECM - MS to come.

Stock AFM - MS to come.

NB O2 - Wideband to be installed in downpipe, close to turbo.

MSD FPR - MS to come. Funny analogy and pretty spot on. lol.

Fuel Rail - I made it out of fluted stock. Inside diameter is about 14mm. Good?

MSD 6a - actually dead. Was going to replace with a MSD 6-BTM. Neccesary if going MS? Suggestion?

NA 5sp - no, it hasnt held up well in his Z. It's shot as well. Have no idea which direction to go here. Trying to keep the costs down but also obviously need something stonger with his build/shifting habits. Ideas? I've been running this tranny on my Z with about 300hp without issue for a bunch years. We blew the T5's a few times so we sh*tcanned that idea.

390 LSD - woops, been a while. It's the 300zx 3.70.

NPR IC - It's not tight to the radiator. I thoght that would run the temps up in both the radiator from air restriction, and the IC air temp from radiator heat? Guess i'm wrong on this. IC piping all tight, just about pipe to pipe.

 

Tony - Thanks. We decided against the forged & to invest the $ in a standalone. Correct tune is everything at this point and should help stop grenading things, for a little while anyway! MS should help with this. Not planning on anything over 7k so we should be good. Had a metal 1mm head gasket in there and was thinking of re-using it. No good? I do like your "Maximum Boost" style build. Makes perfect sense. That will be on the list for sure after we get the MS installed and running good. And yes Gollum, i agree with you as well - when we do the head porting to create maximum flow & lower pressures, i'm sure we're not going to be able to hold back from cranking it all back up again to push its "new" limits. You know how it goes - 'lil more, 'lil more... damn... too much! ha.

 

Infaltrate, Evil, Benardd - Thanks a bunch for the info. Much appreciated.

 

Bottom line - HEAT KILLS. Tune it right.

 

- Jersey

[infiltrate2000]

Jersey, for trans option you can try a 240sx ka transmission. This is what my friend currently has in his car. You can get these transmission cheap i have seen them go for $100-200. You have to swap the bellhousing from the L series trans and modify it a little.

http://atlanticz.ca/...tall/index.html

I like how the shift too.

Edited December 1, 2012 by infiltrate2000

[Gollum]

Thanks a bunch guys for all the responces. Alot of info shared and appreciate it all. I love to learn and build knowledge. Attention from some of the big wigs huh? Ut oh... i'm in trouble. lol. Ok, so here's the route we decided to go as of yesterday morning.

 

Ordered a set of ITM standard size pistons/rings/rod bearings, ARP head bolts, Wideband O2.

 

We were also going to install a standalone (most likely MegaSquirt) at this time but figure we'd get it running like this first, on LOW boost, just to make sure everything's ok. Once it all checks out, install the MS & get this thing tuned correctly, or at least a sh*tload better than poking and hoping. We built it on the cheap without standalone and we all know that only lasts just so long before stuff starts breaking, which it has. I'm SURE it's running real rich down low and extremely lean up top creating massive heat, causing pre-ignition/detonation. The MS should put us on the right track and to also see if the 370's can supply enough fuel for this T3/T4.

 

Gollum - Thanks. To respond to some of your suggestions...

 

H-Lifters - all in good condition and working properly.

370's - Hoping they'll be enough once we go MS. We shall see. Suggestions on a good RRFRP? Not trying to prove a point, just didnt have the cashflow to go standalone during the initial build. Always costs more in the long run, huh? lol.

Notice how the one on this site, though overpriced (you can find a unit just as good for almost half this) expressly advertizes the ability to adjust the ratio of extra fuel per PSI of boost. The cheapies get MAYBE 3:1 which is almost useless. Most calculations and real world experience points towards 7:1 being a much better ratio. Every build is different though so it needs to be treated uniquely. What I'd like to see is someone make one that can also start raising pressure at someone OTHER than 1psi, like say 10psi where a lot of stock turbo car's maps start to lean out and run out of fuel. Being able to adjust this spot it starts boosting fuel pressure would help cure rich/lean spots caused by RRFPRs. http://store.schnitzracing.com/rcc-billet-raising-rate-fuel-pressure-regulator/?gclid=CKDAspGc-7MCFYN_QgodngcAUQ

60mm TB - just one of those things. Was hoping for a lil quicker throttle responce, almost seems too much, very sensitive. Should be good once MS installed.

Yea, 60mm can be pretty crazy on a stockish setup. Simple actuation adjustment can go a long way, basically causing it to open more slowly at the beginning of pedal travel.

BOV & BC - BOV is recirculated toward turbo to help keep spool, short pipe. No rice here at age 45 & 50 but, we do enjoy eating rice! lol. The BC is a TurboXS, not electric type. Sorry fr the misinfo.

Sweet. No worries. Just some pet peeves of mine. Glad to hear you're on the right track.

Stock ECM - MS to come.

Stock AFM - MS to come.

NB O2 - Wideband to be installed in downpipe, close to turbo.

Not TOO close. But close, yes. I've seen turbulence distortion from being within 2" of downpipe flange.

MSD FPR - MS to come. Funny analogy and pretty spot on. lol.

Fuel Rail - I made it out of fluted stock. Inside diameter is about 14mm. Good?

Not positive. Tony knows the numbers better off the top of his head than I do. I'd have to do a search. If you do a search on here I'm sure you'll find something.

MSD 6a - actually dead. Was going to replace with a MSD 6-BTM. Neccesary if going MS? Suggestion?

Ideally, I'd go COP/Wasted Spark and use the new trigger wheel available from DIYAutoTune. They make a disc that plops right into the dizzy and gives MS a signal that's as reliable as a crank pully trigger, as long as your oil pump doesn't jump a gear (unlikely at less than 400whp). Then you can use that signal to drive any type of coil pack setup that has built it igniters so you're not overloading the built in MS ones. Just use MS to trigger and you'll be just fine.

NA 5sp - no, it hasnt held up well in his Z. It's shot as well. Have no idea which direction to go here. Trying to keep the costs down but also obviously need something stonger with his build/shifting habits. Ideas? I've been running this tranny on my Z with about 300hp without issue for a bunch years. We blew the T5's a few times so we sh*tcanned that idea.

Z32 Trans. Nuff said there. There's guys using the 240SX trans like infiltrate mentioned, but even those guys running big numbers often switch to the more robust Z32 trans. They're not absurdly expensive and there's a sticky on how to do the swap in the FAQ section.

390 LSD - woops, been a while. It's the 300zx 3.70.

No worries. It's possible to convert a 3.9, just curious if you had.

NPR IC - It's not tight to the radiator. I thoght that would run the temps up in both the radiator from air restriction, and the IC air temp from radiator heat? Guess i'm wrong on this. IC piping all tight, just about pipe to pipe.

You don't necessarily need it TIGHT to the radiator, you just want to make sure air has a direct path from one to the next. Ideally you could use about a 1" duct and use a foam seal on both sides to keep air from escaping, but even just foam between the intercooler and radiator will yield good results. The issue is that if there's any decent gap between the two, a lot of air just goes AROUND the intercooler, not THROUGH. You want to force air THROUGH and offer the intercooler as one of the few means for escape from the pressure. I believe this is all well covered in the windtunnel section. Again, in a "perfect world" that doesn't exist, you'd have your front inlet duct to an intercooler, with NO air able to go around, then duct to the radiator with NO air able to go around, and you'd never have an angle greater than 15 degrees to keep laminar air flow... Just ain't happening. But we can do what we can. Put some rubber, foam, hell, anything between the intercooler and radiator and log some temperature differences and see for yourself.

[Tony D]

I'd just restrain myself to 10psi and the stock regulator until you get standalone. the RRFPR will be teats on a boar hog soon as you get the standalone, why waste the money. It's a 1960's solution for using STOCK injectors to retain driveability at idle while expanding power on the top end WITHOUT larger injectors. Not a big RRFPR Fan...

 

Agreed, just go COP or even stockish Z31 coil with the GM Driver initially, no need for a BTM when you have MS, you will directly program the spark retard, and not simply pull in a linear fashion.

 

I like the Turbo XS Boost Controller, the dual solenoid so you have a "lo" and "hi" boost. Hell, they have four solenoids now so you can use one pressure per gear (which actually is needed in some applications...I was going to make due on the Bonneville car with two pressures, but now likely will employ that one. 8# in first (350HP), 17 in third (650), 25 in fourth (more than 650) and the full monty of 30 psi in fifth if we can keep it on the ground. What we likely will do is tailor each boost to wheel spin propensity at speed or while accelerating... but I digress....

 

GET A DETONATION STETHESCOPE! I don't care if it's some latex tubing to a harbor freight mechanic's steth earpieces or some garden hoses siliconed into old ear defenders---DO NOT rely on you being able to hear the detonation while tuning. Especially at your age.... The 'Electronic Ears' sold by the previously mentioned company are the ticket for tuning a good curve. You can make this on your own if you know how to amplify the signal from the VW Knock Sensor---then ouptut it to any set of ear buds or earphones. There was a Dodge Website that had a circuit on it...but that was several laptops ago...I wouldnt know where to start now to link you to that one!!!

[Bernardd]

Here's a link to a diy setup that works fairly well. http://www.uprev.com/documentation/Knock%20Listen%20Device.pdf

I've use both electronic and a hose attached with a bolt to the block. Next year I'm going to run the knock sensor into a

laptop. Here's a link to how that sounds.

http://soundcloud.com/immy21/timing-added-short

[Jersey]

Thanks guys. Think we're just going to build it back up, low boost, prob like Tony mentioned 10psi for a little bit then install MS. I havent done all my reading on MS yet so no idea about how we're going to control spark. I'm thinking as simple as possible until i get comfortable tuning w/MS and all bugs worked out. One step at a time before we're chasing our tails for days wondering what change did what. I do know that the 10psi setup wont last long because it wont be enough for him, he knows how to adjust the BC and, he has a real tough time keeping his foot out of it! ha.

 

I need to look into how the knock sensor circuit works but rather than an audible alert, i'd love to have it light up an LED on the dash when it detects any signs of detonation. Can be a tad loud in the Z and he's hard of hearing anyway. That's what his wife says anyway. ha.

 

Thanks for all the input guys. Keep ya'll posted.

 

- Len