RB25DE, RB26 NA or L28 rebuild 280z restomod

[Classic Z]

Hi

If anyone on here has previous experience or has undertaken such a project I would be grateful for their advice and help in the following.

I am building a street able and possibly a light competition car. Something to have fun with.

What I imagine is a high revving, very responsive engine with uprated brakes and suspension and a stiffened chassis. I am looking for around 180 to 200 wheel horsepower. The type of car that is not stupidly quick, but something that you can rev out and enjoy pushing through the bends and enjoy through the whole rev range. Not an all out track car with all the power at the top end.

I have built a few projects my self and am looking to build the engine myself. At the moment I have my 280z with the stock L28 engine with stock EFI system. I have got it running but don't like the way the engine performs. It seems to have a bit of torque but is sluggish/lazy. It is not a free revving, spirited engine. This could be because it has lost its performance as its old and has an out dated EFI system but from what I have read the L28 is a long stroke engine so not high revving and responsive.

This has led me to consider, from what I can see are the 3 options. I want to keep the car naturally aspirated.

1. Rebuild my L28 and increase compressing as from research its a low compression motor. Also add triple Webbers and some cylinder head work (CAM etc.) I am not to hopeful as from what I can tell the L28 is a long stroke engine so even after this work it wont be high revving and will not be very responsive. Also the stock 5 speed gearbox does not seem great for this application.

2. Source an RB25DE as I want to keep the car naturally aspirated. From my research these engines rev higher and make about 150 wheel horsepower. So with this engine I may get away with a simple refresh and possibly some cylinder head work, cams etc to squeeze a bit more power out of it.
I will need new mounts, prop shaft, wiring loom etc.

3. Source an RB26 and turn it into a naturally aspirated engine just like Sung Kang's
build. This seems to be the more expensive option rather than the RB25. I have done some research and it seems in order to raise the compression of the RB26 I would need to install high compression pistons and stronger rods, change the CAMS, New springs and possibly port and polish the head. I would want to produce an engine that has performance through the rev range though and not all at the top end. I will also need a wiring harness kit, new sump to fit the S30 chassis, ECU and prop shaft made. I calculated this all to cost, including the purchase of the engine and gearbox (RB25 gearbox) to be about £7k if I build it my self.

So if anyone has any experience in this it would be great to hear their opinion and what they have done.

Many thanks
Paul

 

[jonbills]

the L28 isn't a long stroke engine. its only 79mm stroke. its just a longer stroke than the L24 which is very short stroke at 76.7mm.
I have an L28 that revs to 8500 regularly. You need lightish and balanced rods and pistons and the crank, flywheel, clutch assembly balanced. then you need a head that can flow well and carbs or ITBs with enough airflow to supply it. It is quite an expensive business!

 

[Classic Z]

Thanks for the reply.
So there is hope for the L28 then. Good news. Do you use the stock 5 speed gearbox?

What did it cost you to build your engine?

I plan on building the engine myself. Do you have any idea how much the parts would cost or where to buy them from? I only have experience with V8 engine builds so different suppliers.

 

[datsfun]

If you are considering engine swaps and want to keep NA, have you thought of non Nissan engines ?

 

[Classic Z]

Yes have done but really want to keep to the Nissan family of engines.

 

[Mark N]

Out of your three options, I would go for the L28.
There are loads of modern tuning options such as ITBs, COP and ECUs.
The RB25DE would be a lot of work and expense for pretty much no gain over a tuned L28.
There are also very few tuning options for the RB25DE.
Why on earth would you want to go through the expense of crippling an iconic engine like the RB26 by making it naturally aspirated?
There's a reason Nissan never made an RB26DE..............it's a shit idea!
Plus, I doubt you could do it right for £7k, you would need custom pistons, camshafts, exhaust manifold and ECU plus all the parts for the S30 swap.
Then you will need an uprated oil pump for high revs, if it is an R32 engine it will require a crank collar fitted, then machining on the block (hone minimum), headwork, etc, etc.
I've built an RB26 single turbo engine with most of the parts being bought many years ago, when the pound was strong against the USD any JPY, and it cost me around twice that.

 

[datsfun]

Have you considered the 350/370z engines as a donor? There is a guy who has done this stateside ( seen his facebook posts on DPAN) and uses his car for fast road and track work and is very happy with the balance and power

 

[jonbills]

Thanks for the reply.
So there is hope for the L28 then. Good news. Do you use the stock 5 speed gearbox?

What did it cost you to build your engine?

I plan on building the engine myself. Do you have any idea how much the parts would cost or where to buy them from? I only have experience with V8 engine builds so different suppliers.

I use an fs5w71c box from an s13 200sx. Its the same family of gearboxes, but slightly stronger and more modern. a popular mod. but 200nhp on the standard box should be OK.
My engine build was I suppose 6 or 7k, if I exclude all the inlet and outlet stuff. 50/50 between bottom end and head. i don't think you'd need to spend all that for 200 fwhp though.

I'd suggest starting with the 'how to rebuild your nissan ohc' and 'how to. modify your nissan ohc' books, they're a great primer. also lots of good threads on hybridz.org about modifying these engines.

 

[Classic Z]

Have you considered the 350/370z engines as a donor? There is a guy who has done this stateside ( seen his facebook posts on DPAN) and uses his car for fast road and track work and is very happy with the balance and power

Hi Yes I love the 350z engine as I use to have one. Really is an amazing engine and sounds awesome with the right exhaust but needs to be a straight six for this build.

 

[Classic Z]

Out of your three options, I would go for the L28.
There are loads of modern tuning options such as ITBs, COP and ECUs.
The RB25DE would be a lot of work and expense for pretty much no gain over a tuned L28.
There are also very few tuning options for the RB25DE.
Why on earth would you want to go through the expense of crippling an iconic engine like the RB26 by making it naturally aspirated?
There's a reason Nissan never made an RB26DE..............it's a shit idea!
Plus, I doubt you could do it right for £7k, you would need custom pistons, camshafts, exhaust manifold and ECU plus all the parts for the S30 swap.
Then you will need an uprated oil pump for high revs, if it is an R32 engine it will require a crank collar fitted, then machining on the block (hone minimum), headwork, etc, etc.
I've built an RB26 single turbo engine with most of the parts being bought many years ago, when the pound was strong against the USD any JPY, and it cost me around twice that.

Out of your three options, I would go for the L28.
There are loads of modern tuning options such as ITBs, COP and ECUs.
The RB25DE would be a lot of work and expense for pretty much no gain over a tuned L28.
There are also very few tuning options for the RB25DE.
Why on earth would you want to go through the expense of crippling an iconic engine like the RB26 by making it naturally aspirated?
There's a reason Nissan never made an RB26DE..............it's a shit idea!
Plus, I doubt you could do it right for £7k, you would need custom pistons, camshafts, exhaust manifold and ECU plus all the parts for the S30 swap.
Then you will need an uprated oil pump for high revs, if it is an R32 engine it will require a crank collar fitted, then machining on the block (hone minimum), headwork, etc, etc.
I've built an RB26 single turbo engine with most of the parts being bought many years ago, when the pound was strong against the USD any JPY, and it cost me around twice that.

Thanks. Yes that's what I am trying to figure out in terms of cost. If I build the L28 then I will go with triple webers as the ITBs all in with ECU etc comes in at about 5k ish or more. I am only looking for around 180 to 200 wheel horsepower. I just wondered if its possible to build an L28 which would be high revving and responsive. As Jonbills said, its seems possible.

Makes sense from what you said about the rb25. The reason for the rb26 naturally aspirated idea came from the 240z fuguz Sung Kang built. I love NA engines and the one the RB26 he built has about 240 wheel horse power. Impressive but as you say maybe more than the 7 k I thought would be enough. Maybe I am use to v8 engines. I recently built a 351 Windsor including the machine work, new bearings all around, new water pump, oil pump, fuel pump and a set of band new heads, performance cam, carborator etc. for around 3.5 to 4k. I built it myself. The shop wanted around 8 to 10 k to build it for me.

Thanks for the advice.

 

[richiep]

An rebuilt L28 with suitable porting, cam, balancing etc, triple carbs, can easily hit 200 fwhp. The stock 5-speed will be fine, unless you fancy the more modern precise shift feel of the “71c” S13/14/14a 200sx boxes, especially when matched with a short shifter kit (which are cheap at £30ish).

Research is key for you now. The books Jon mentioned are very useful, forum threads here and on hybridz. Have a look at the engine parts available from Kameari in Japan for the good performance stuff. Use RHDJapan to browse all that good stuff. Rockauto, zcardepot, and other are good in the US.

 

[Classic Z]

An rebuilt L28 with suitable porting, cam, balancing etc, triple carbs, can easily hit 200 fwhp. The stock 5-speed will be fine, unless you fancy the more modern precise shift feel of the “71c” S13/14/14a 200sx boxes, especially when matched with a short shifter kit (which are cheap at £30ish).

Research is key for you now. The books Jon mentioned are very useful, forum threads here and on hybridz. Have a look at the engine parts available from Kameari in Japan for the good performance stuff. Use RHDJapan to browse all that good stuff. Rockauto, zcardepot, and other are good in the US.

Most helpful. Its good to know that I can achieve what I am looking for from the L28 engine. I will go with the 71c transmission as I beleive it will feel a lot better that the stock transmission. Its hard to find those though. I will also go with triple weber setup as the ITB system with the ECU etc. is very pricy.

Thanks also for the recommendations on suppliers. I realize there are a lot of cheap/bad quality engine parts available so would want to avoid them.

 

[Alphabettispaghetti]

I’d go oer for the carbs(Weber jet version) as it’s ‘cheap’ for a manifold and carb package.

 

[Classic Z]

I’d go oer for the carbs(Weber jet version) as it’s ‘cheap’ for a manifold and carb package.

Thanks Franky
Do you know where to get them from? Any idea of price?

 

[atomman]

Thanks Franky
Do you know where to get them from? Any idea of price?

https://www.rhdjapan.com/oer-carburetor-kit-45mm-rod-type.html

Sale on to

 

[Woody928]

It sounds like you're building the same car as me, you obviously have good taste

The Fugu Z engine sounds absolutely epic and revs to over 8k rpm however I think is out of the budget of most of us mere mortals sadly!

I'm still waiting for lockdown to end to recover my L28 to start stripping it however I literally have exactly the same goals, I started a thread and have been getting lots of help and useful ideas:

https://zclub.net/community/index.php?threads/l28-fast-road-engine-rebuild-advice-wanted.26773/

You'll likely end up realising the same thing that I now have, which is that you don't have to spend mega money to get the desired power levels however to get the high revving engine characteristics you will need to go for aftermarket forged and balanced bottom end. This will dramatically increase the expense and you'll likely end up with more power than you're strictly after...

I still can't work out which way I want to go, however I love the idea of a high revving engine which feels special! This is a complicated minefield to be wandering through...

 

[jonbills]

the main thing I think for the revs is balance. so it you've got the *time* to balance the stock pistons and rods then I think you should be able to get it to rev well too.

 

[Mark N]

the main thing I think for the revs is balance. so it you've got the *time* to balance the stock pistons and rods then I think you should be able yo get it to rev well too.

It is a little time consuming, but the hardest part is trying to find accurate enough scales and not look like a drug dealer.

 

[Classic Z]

It sounds like you're building the same car as me, you obviously have good taste

The Fugu Z engine sounds absolutely epic and revs to over 8k rpm however I think is out of the budget of most of us mere mortals sadly!

I'm still waiting for lockdown to end to recover my L28 to start stripping it however I literally have exactly the same goals, I started a thread and have been getting lots of help and useful ideas:

https://zclub.net/community/index.php?threads/l28-fast-road-engine-rebuild-advice-wanted.26773/

You'll likely end up realising the same thing that I now have, which is that you don't have to spend mega money to get the desired power levels however to get the high revving engine characteristics you will need to go for aftermarket forged and balanced bottom end. This will dramatically increase the expense and you'll likely end up with more power than you're strictly after...

I still can't work out which way I want to go, however I love the idea of a high revving engine which feels special! This is a complicated minefield to be wandering through...

Hi Woody

Yes it seems like we are after the same engine : ) Where are you based?
Are you planning on changing your transmission also to a 200sx one.
I cant wait to start building it. I recently rebuild a 1969 351 Windsor V8 from the bottom up. Changed nearly everything and started it for the first time this Wednesday. Sounds amazing. Really enjoy building engines.
Thanks for the thread will look at it this weekend.

 

[Classic Z]

Hi. Can anyone here help out please with the 200sx gearbox replacement.

I have been looking into purchasing a 200sx gearbox and am finding it very confusing as there seems to be different types. The casings and bell housing castings all look different.

I have found one for sale and asked for the number that is stamped on the casting and the picture I was sent says. RP71C and underneath it has a #2
Is this the 71c transmission that is suggested. The advert says it will fit an RB20, Rb25, Rb26 and Rb30

The other thread from USA is giving a different casting number but I believe it is from a 240sx number is FS5W71C so still a 71C

Will any 71c work?

Thanks