240z tuning...

[Alphabettispaghetti]

Right, i've had a good search.

A 2.4 engine car, not wanting to go any bigger as i'd prefer a revvy/'peppy' engine.

Its a 1970 car so e31 head, I'd like a genuine 150ish bhp out of it, 140 at the wheels would be nice. Is there a tried and tested way to get to this sort of figure?

I was thinking a 10:1 compression ratio(should be fine on decent fuel). A 280ish cam. A bit of home porting, matching the manifold to the head+gaskets etc, keeping the SU's and a 6-2-1 manifold.

To help the engine rev freely also removing the mechanical fuel pump and the engine mounted fan. Would it be possible to get a reliable 150bhp at the wheels?

I've had a car with genuine 480bhp/tonne before so I know I don't want monster power, just a nice useable toy.

Does this sound like a reasonable expectation? I'll set the car up as best as possible as it is first, take it to a rolling road so i've got a point to start from.

 

[Rob Gaskin]

Like you I thought I needed to stay 2.4 to keep a revvy engine. I then started to go short-stroke 2.6 for the same reason but more power.

In the end I went 2.8 after I was advised that increased capacity is easier power and 'hey they rev ok anyway'.

Yep he was right, it revs like a good-un. I use 7k a lot.

I was also advised by the same person that 'SUs are great carbs' and again he proved to be correct (I have 2" though, HD8).

If you stay 2.4 I would think you could get the 150, I had 175 atw with 2.8 (mech pump and fan but now changed to electric)

Not massive power but enough to enjoy my 240 without breaking the bank or driveshafts.

 

[amocrace]

i rev my 2.8 to 8500, never had an issue with drive shafts with decent surfaces and i have 280 flywheel bhp, cant remember what it gives at the wheels!
as our US cousins would say there aint no substitute for cu ins

 

[Alphabettispaghetti]

I understand a bigger engine will still rev but I doubt it'll feel the same. Besides I can't find any 2.8's

 

[status]

i have a 260 lump sitting here, for sale .from wot i had done in the past was a 260 bored out to 2.8 which was nice and revvy and went really well,from wot i remember if you use a 260 block and bore it out it ends up a tad more than a 2.8,that was wot i was told anyway,im sure someone on here may be able to add to this

 

[pmac]

i have a 260 lump sitting here, for sale .from wot i had done in the past was a 260 bored out to 2.8 which was nice and revvy and went really well,from wot i remember if you use a 260 block and bore it out it ends up a tad more than a 2.8,that was wot i was told anyway,im sure someone on here may be able to add to this

Paul. Boring out a 83mm block to 86mm is possible .... but not guaranteed to work . depends on the quality of the block.

 

[Alphabettispaghetti]

It'd still be a longer stroke though too I guess?

 

[pmac]

It'd still be a longer stroke though too I guess?

if you bore out a 260Z block and use a 260 crank then you end up with a 280 engine. So longer stroke.
If you use the 240Z crank then you have a short stroke 260 engine effectively.

 

[status]

Cheers Pete,ive leant something today,Kevin irons (samuri)done mine,went like stink,if you cant find a 28 then try a 26,think it all depends on the cam you put in also,also my old 240 had some head work and was nice and revy and great fun to drive