Big Bore 3.1 or 3.2

[RaysirX]

I am building a stroker motor with P90 heads and an F54 block with a diesel crank. Question #1. Is it possible to build a 3.2L motor? If so how? Question #2. Who makes the best pistons for the 3.1 or.2 application.

Question #3. What type of cam duration is best? I currently have a set of triple Mikuni carbs.

[datsunlover]

I would have to say that all those questions depend on what you want to do with the motor/car.. street, drag, autocross.. ect. so as for 'the best cam duration', I think it depends on personal preference and/or the proven track record of a particular brand. If you look through an aftermarket catalog (like Victoria British for example), they give specs and aplications of all their cams, and most other aftermarket items they sell.

I don't know if you could bore it to a 3.2, but I supose anything is possible.. as long as there is enough material/space in the block to do so. Something I have been told though (by a profesional engine builder in my area) is that boring out an engine does not get you HUGE hp/torqe gains; it is the head work and cam, along with the exhast that makes power.

[Guest bastaad525]

Especially with L series motors... all the HP is in the head and induction system. You will get more torque with a 3.0L setup than say stock 2.8, but if I had the money I'd spend every dime I had on headwork and only bore out the block a little, maybe to 2.9, and keep the stock 280 crank. This can be easily done with only .060 over pistons.

 

Not to deter you though, there are a lot of guys making really good power with the 3.0L+ setups. If you want better info you can talk to the guys at Rebello, they have made a business out of making stroker L engines, and really seem to know their stuff.

[Ivan280zt]

i saw one of the Rebello's cars while back it was red turbo z with huge flares making something like 500hp+ but i can swear that in the spec sheet they listed that engine to be 3.5l does anyone know the car that i am talking about? 3.5l sounds awfully alot because as far as i know (from readin around z boards) biggest that people go is 3.1 and thats pushing it becasuse cylinder walls are too thin and even that requires perfect block.

 

Ivan

[Thumper]

Two very helpful sites.

http://www.zhome.com/rnt/L28conversion/3031FAQ.html

http://www.zhome.com/rnt/3.1HanveyProject.htm

 

Good luck

[RB26powered74zcar]

Piston size isn't the only way to get that 3.x L engine. Crank throw/rod length, piston pin height all can make for a stroker

The last thing you want to do is get it by only boaring the hole out to the max, or you'll end up learning the hard way as I did with tin foil thin cyl. walls that I could push thru them with a pair of channel lock pliers.

 

I cracked two cyl walls on two seperate F54 blocks, trying to build the "3.1 L stroker, because the cyl walls ended up being to thin after the bore job.

I will no longer go bigger than 88mm - 88.5mm, just so I'm sure that will not happen to me again.

 

Now if you have access to a sonic machine, to assure the factory bore casting is perfectly centered in the block, you may get away with more than I did.

Mine were shifted to one side more than the other on most of my bores...

 

This was my hard learned experince...

[z-ya]

Yes, Rebello can build you a 3.2L. I know, a good freind has one. 305HP at the crank. Sounds unbeleivable with a Sebring muffler.

 

I assume that it's just bored more than a 3.1L.

 

I'll go along with what bastaad525 said. Spend your money on head work, and bore it to a 3.1L maximum.

 

Pete

[Dan Baldwin]

If you're not planning on going over ~7500 rpm, stock Nissan pistons should be adequate. KA24E pistons come in 89mm, 89.5mm, and 90mm. In my recent 3.1 rebuild, it was overbored another .5mm with the 89.5mm pistons. 89mm w/ diesel crank = 3098cc, 89.5mm=>3133cc, 90mm=>3168cc.

 

FWIW, when I had the block ultrasonically checked before the rebuild, min wall thicknesses were around 0.110", with the bores well-centered in the block. With the additional overbore, I'm at ~0.100" wall thickness now. I don't know if I'd want to go any further.

 

Torque will pretty much increase linearly with displacement, so more is always better in that regard. Just a question of risk vs. reward.

 

As far as cam duration, this is totally dependent on your application. How will the car be actually used? A street motor will have far less cam duration and lift than a drag or track car. It's best to be honest about what you want the car for, mine is a dog from a stop unless you really give it a dragstrip launch, which you don't want to have to do to beat the ricer/musclecar/eurotrash next to you at a traffic light.

[zolorin]

3.5 stokers are for the VG30 seriest engines. They save a special crank made for the 3.3 and 3.5 liter, but you should ask a Z31 club or Twin Turbo club on how it is done. For the larger L3x storker you could go to custom crank of 86mm and 90mm pistons with pin height of 24.7mm and some other stuff and get 3.3 litre stroker but at that you are asking for trouble. 160 thousands can be done on some of the blocks but if you are going that route (for more displacement) get anouther engine to work with, it will cost you much less then getting the max of the L series engines. My self I am going L30ETS route only bore it out to 87.5 mm and run a lot of boost. L series rock but there are always limits on how much you can go before it is too much. and do search button