Switching from 1st gen turbo Z to 240sx turbo!

[Pyro]

Hi guys!

I have been searching around on your site and I'm pretty impressed!

I have been a 1st generation Z guy for many years now. I have three old Z's, one stock, one with a chevy V8, and the other with a t3/t4 turbo. But, I have decided to sell all my Z's and get a 240sx for two reasons. 1) I'm tired of the primative conditions in a first generation Z, and 2) My wife is pregant and I need a back seat.

I know my Z's and what it takes to add a retro-fit turbo to a old Z engine. I know all the engine combo needed to lower the compression and engine managment stuff for the Z. But the 240sx is a totally different animal and when it comes to knowledge on this car I'm back to being a freshman. So, I have a few simple questions if you don't mind answering. I have done a fair amount of searching but really haven't found the answers.

I was hoping to keep it simple and cheap and get a 240sx with the KA type engine. Is the DE engine that much better than the E?

How is the compression lowed in these engines or can the engine be turbo charged with the stock compression?

I like the fact that the 240sx came with a OD automatic but how well does the automatic hold up to the turbo? Is the 5 spd a better way to go?

How much is a typical exhaust manifold for a turbo or can the stock one be modified?

I have a few extra straight T3's laying around and would like to use one of those with an automatic transmission. Any comments?

Right now, I'm looking for only 220 to 240 hp at the wheels and a good daily driver.

Any special year model car I should be looking for? I was hoping to get all the options in a mid to late 90's car. I know I don't want a hatch back anymore.

Sorry for all the questions but I'm in a hurry. The wife is due in May!

Thanks.

[IvanAtSPRacing]

There is more availble for the DE then the E. I would recomend the DE. The E motor was in the 89-90 where the DE was in 91-98.

Lowering compression is done with pistons. Stock pistons are the weak link in the performance chain on the KA. The ring lands crack. If your shooting for over 300 whp, I would consider forged pistons. I have made just over 400 whp several times on the stock pistons right before they fail. Do a compression test on your motor and if its good, your golden for lower boost applications (ie 6-10 psi)

I have heard that the factory AT can be built to hold decent HP 400+

Check out the sponsor of this forum for a very inexpensive turbo manifold. Lots of cheap manifolds on Ebay. be carefull and check the reputation of vendors prior to purchase. Most of the ebay stuff tends to fail. I have never heard of anybody modding the factory mani for turbo applicaton.

T3 turbo would be fine.

Your HP goals are very reasonable.

95 S14 body. Bigger then S13, more refined, OBD1.

Hope this helps

[WDRacing]

Alot of the 95's are OBDII, Mine is. Depends on when it was built etc. I have been told that internally the auto transmission is the same as the GTS-t R32 Skyline. I persoanlly know that they'll push 340whp with no problems.

EBay is fine so longs as you stay away from SSautochrome manifolds and any knock off by them. They are supposed equal length mani's, all stainless steal, with a turbo flange built to accept a T3 or T4 turbo. They are not very high in quality and do not fit on a S14 with ABS.

Welcome to NICO. Feel free to ask anything.

WD

[IvanAtSPRacing]

Wally Dallenbach (WD) Speaking of OBDII, how do you know. I have both ports in BOTH my early 95s and neither of the OBDII port link to my scan tool. Are you SURE that they are considered OBDII. I can unplug my rear O2 and not catch a CEL. AEM says they have two different EMS units for the 95 and I cant get a straight answer from them as to what to look for.

[hannibal]

Welcome to NICO (and the 240sx!)If you wanna learn something, youre in the right place.

Ivan, From my research, the earliest 95's were obd 1, there were a few obd1+ built (obd2 connector but not all the functions are available), but the latest 95 are fully obd2 compliant. Ive actually heard of more obd2 95's than obd1. Apparently Nissan got a pretty good head start.

MarkeMark has experience with this. He went thru a lot to verify he has a full obd2 95 model...

[Bronze MFP]

a quick check in the engine bay will let you know if you have obd I or II.I compared my bay(95 OBDI) to a 96 obdII, and the 96 had a larger harness with 2 different wiring harnesses located in front of the intake manifold and a lot more vacume lines running all over the place. As for the generic scann tool port, I have one, and my car is definitly OBDI, so you can't rely on that for identification.

[Pyro]

Thanks for the help everyone!

Looks like I need to start looking for a late model, automatic, with DE engine.

So, I think you are saying that if I keep the boost low (6 to 10), the stock compression ratio doesn't need to be lowered. Is that right??

What is an obd I and obd II? Is that the ecu type or number of cams?

So, if I do what to lower the compression are there any "off the shelf pistons" that would work or is it a costom job? I would rather use cast pistons for the quieter operation and for less wear. Besides, 10 psi is about all I'm trying to boost. (maybe 12) so forged may not be needed.

Old z's are easy. Just pick the right stock pistons and the right cc head to get the proper compression ratio for a turbo. And there are factory turbo manifolds everywhere!

[WDRacing]

Well, as far as pistons go, there a ton of "off the shelf" units. However, I don't know any cast ones. The big thing is the ring lands, so if you get a set of cast ones made, don't use the stock ones as an example. The first ring land is very thin. If you find a car with good compression then you don't need to replace anything internally anyway. The stock internals have been proven to work at 350whp with no problems. I would worry when you pass that point.

OBD1 and OBDII are the ecu's and emmisions equipment that are installed.

Any idea yet what you plan on using for engine managment? For simplicity, I'd say get a JWT rom tune or Enthalpy rom tune. Or use the new AEM EMS, but I wouldn't go with AEM unless your wanting big numbers.

WD

[Pyro]

That is a good question! I have no idea what engine mangement is available for the 240sx's. I was thinking of doing an aftermarket setup like haltex, speed pro, or maybe even megasquirt. But it sounds like there are better ways than that. Are the rom tunes a reprogram of a stock ecu?

I was planning to get my old Z cars sold and the new 240sx bought before planning the turbo install and engine management.

But since we are on the subject........How would a very simple FMU work on these cars? Increasing fuel pressure during boost is a simple management tool. However, there is no timing control. That is what I have on my Z and I can run 15 psi of boost using the stock NA injectors. However, I don't want to re-invent the wheel. I want to use the normal stuff. In any case, it sounds like I need to do the rom tunes.

[WDRacing]

A FMU will work, but not for more then 8 lbs of boost. After that you'll have a tad to much fuel pressure for my liking. Besides, at 8 psi you'll need some timing retard. The JWT ECU is a rom tune of your stock ecu. Well kind of, they install a daughter board...etc.

[Pyro]

Thanks.

I'm starting to get it! I have been searching the site for "rom" and came up with a bunch of information.

On my old 280, I reduced the mechanical advance so that it would only advance 8 degrees. The vacuum advance would go another 10 but would shut down when the boost came in (how nice!). 20 initial plus 8 mechanical plus 10 vacuum advance would give pretty high timing during off boost driving and only 28 on boost. Primative timing control but it worked. I doubt the 240sx uses a mechanical advance distributor. That is almost like having a hand crank on the end of the engine to start it! LOL.

Thanks again!!

[WDRacing]

You could use the MSD BTM for timing retard on boost. It retards anywhere from 0-3 degree's of timing per lb of boost, the user decideds how much retard.

[Pyro]

Yes, I have seen those boost retarders in action. But I keep thinking that all these indiviual modifications (fmu, fuel pumps, boost retards) adds up in cost to one aftermarket efi system. Maybe I should just bite the bullet and buy a complete system and trash the factory stuff. Then I would have complete fuel and timing control with just a lap top computer.

I tend to go for the cheap way but it ends up costing more money and time in the long run! Maybe I can turn a new page and do it different this time. LOL...

Thanks for all your help. I'll keep the borad updated on the progress.

[WDRacing]

If you go with any kind of standalone, get the AEM EMS. Its a complete standalone only its plug and play. Just plug it directly into the stock harness and go. No sensors, no mag pickup, just turn on the laptop and roll.