Turbo enigine combintations??

[Cody 82 ZXT]

Well, I guess it's finally time for me to rebuild my engine. To much boost too little fuel = well you know. I'm looking to rebuild my engine but, don't have a huge budget for the buid up. Hopefully I'll be able to step up to the JWT computer that is based on the Z31 at the same time. With that what do I really need to have or have done? What I'm think of now is just a stock rebuild with some new pistons, timing gear, head rebuild plus the obivious stuff. What recommendations does everyone have? Do I have to have forged pistons? What kind? Where to buy? I really need some advise here.

 

Thanks,

[Lockjaw]

Forged pistons will add about a grand to your bill by the time you get the pistons, pins, rings, and small ends of the rods bushed.

 

I got Ross racing pistons, and they were 68 bucks each, pins were 110, rings we cheap since my buddy got me some sealed power ones, about 65, rods bushed were about 25 each I think, and you have to rebalance which is about 150.

 

I polished the rods, had them shotpeened, and used ARP rod bolts. You also either have to drill an oil hole in the very top of the small end of the rod or two small holes in the small end at a 45 degree angle to the beam to oil the piston pin.

 

If you have to buy pistons, I would bore the engine and pick up some displacement. You can go to 89 mm bore safely, which will give you approx 180 cubic inches. I went to 87 mm and should have gone out the other 2 mm.

 

Good luck, there is no really cheap way to rebuild an L6 if you have to replace pistons. Nissan one's are almost as expensive as forged. You could look for a good used engine, and re-ring and bearing it and go. That would probably be the cheapest way to go.

[Cody 82 ZXT]

Do you really think I need Forged pistons? I'd love to do an over bore but, I'm curious as to the benifit of added displacment vs. cost at the time being. If it's something that I'm not going to be able to do without then thats fine but, I really don't want to put all my eggs in one basket.

 

I've read your running the JWT set-up. How would you rate it. I'd really like to go with a SDS system but, would never have the time to set it up correctly and tune it to it's potential. Thats why I'm thinking of the JWT stuff. They have the experence to do it all and can get almost all the power out of a set-up that is there. They seem to be able to set-up with a little resevre in the A/F ratio. About as plug and play as it gets on this type of thing.

 

Back to the engine. What type of bearings do you recommend?

Anyone ever do some porting of the head at home? Clean-up work?

 

Thanks again!

[scottyMIz]

hey cody i just rebuilt mine and did it all stock and mine works fine well good enuf to break u joints I just went with new rings on the stock pistons had a valve job done and polished the intake ports.So if you don't have alot then just do it stock so far my stock pistons have held up very good.

[Lockjaw]

No I don't think you need to go forged, but I was kind of thinking you may need pistons, and if you do, spend the extra 20 bucks a cylinder and get the forged. To me it is worth it, and when you do forged, they really don't care what the bore size is, it is the same price, which is cool. Ross has their own rings now, and they are plasma moly coated ductile iron, which is what I put in mine, and they have held up very well. They have really never lived below 15psi since I have had them, which is going on 4 years, although usgae is limited. The last 2 have been 19+psi and race fuel only.

 

I like the JWT set-up. I helped them tune the Cobra MAF on my car, and they got me running pretty strong, in my opinion. Drivability is incredible compared to the 280ZXT stuff, especially off boost response. I hit full boost by 2800 rpms, no matter what boost it is.

 

The SDS seems to be a pretty good system too. They have some stuff they did not have, or I did not know they had when I got the JWT stuff, or I likely would have gone the SDS route.

 

In the end, I spent alot of time on the phone with Clark at JWT, and I know he is selling something, but he covered alot of the pro's and con's for me. In the end, since I drove the car all the time, I elected to go with JWT.

 

If I knew someone who had the SDS set-up, and I could play around with it, I could probably say more about it. Alot of people on the board use it, but I got into the JWT stuff right since my friend put me on the computer for his cost, which is way less than retail, the cobra MAF is about 200 bucks, and injectors, which you have to have either way, were about 80 bucks apiece. I bet they are the same as the mercede's one's people are using . It is strictly a plug and play deal which is nice.

 

I think you would be pleased with it, and while I may change mine one day, I think I can pick up more power more economically thru other means. If I had lots of money, and nothing to spend it on, I would change to something like the Tec II or SDS or something.

[SHANE]

if you are interested i have the complete JWT set-up for sale. computer, MAF, photo disc, and 420cc injectors. with this set-up and a big fuel pump i was able to run 25psi on pump gas on the stock motor. also ean the time in my sig.

[Cody 82 ZXT]

Shane,

 

Yes, I'm definatley intreasted in the set-up you have for sale. I sent you an e-mail so we can discuss it further off the board.

 

I haven't even started to take the engine out yet. I'm still gathering parts and info at the moment. I bought a hoist new for 100 bucks and a stand for another 30 so for now I've saved about as much as I've spent on items for the swap. Next pay day I'm getting more tools for the rebuild that I don't already have. I'm really bad about not wanting to pay full retail for things.

 

Once I get the engine out I'll be able to see if I'm gong to have to have new pistons or not. if there is no physical damage to them them I could asume they are ok? What about the rods?

 

Lockjaw you mentioned that you polished the rods. How did you do that? Is that something that I could do at home or is that more of something that must be done at a shop? What about polishing the combustion chamber? I heard that would help to deter detionation. Is that true or do the small bumps form the casting help with swirl?

 

What about compression ratios. I would love a more peppy engine when off boost. Any recommendations? What would my compression ratio be if I put in the 89mm pistions and left the stock head gasket thinkness and didn't shave the head.

 

Sorry about all the questions but, there's not really any one around hear that I trust or know in my area.

 

Anyone know anything about SFD engines in Garland Tx.?

 

Thanks,

[Lockjaw]

I am sure that 89 mm pistons would bump your compression, your piston maker would be able to tell you very easily. I would think in the 8.5 range, but that is just a wild guess.

 

Polishing the rods is something I did with a dremel tool and sanding rolls. Not the fastest way to get it done, but it works, and they looked nice. I got alot of compliments on mine. Just grind all the casting flash off the sides of the beams going lengthwise ie from big end to small end. DO NOT GO ACROSS. Bad stuff can happen there.

 

Leave the old rod bolts in while polishing, and replace them with ARP bolts. YOu can get them from summit, and rod bolts are considered the weakest link in a Datsun bottom end. While I have never seen one fail, I think the 45 bucks or so for the ARP bolts is worth it.

 

I have not polished the combustion chamber, but I would bet the swirl comes from the design of the combustion chamber itself, so polishing shouldn't hurt. Port matching the intake to the head would be good too. I did that. The dremel works good for that too.

 

Let me know if you need any more info. Ordering pistons from a piston maker is going to be an experience in and of itself.

 

Good luck.

[Guest Tim78zt]

Hey Cody, why aren't you taking it to Alamo?

 

Tim78zt

[Cody 82 ZXT]

Tim,

 

I know you had your car built there and had good results. As have many other people. I was truley impressed by thier MR-2 they built a few years ago.

 

But, the truth to the matter is that ever since Steve has gone I've had nothing but, crappy service. Every time I go in there to ask a question or buy something they are short and only want to get me out of the way so they can work on someones Honda. I know they get asked a million questions but, if 'm going to make a big purchase I have to try and be ablsolutly certain that it is exactly what I'm looking for and what the results will be. In short they treat me like crap.