How to get 185BHP

andrew muir

Club Member
Hello
Got a pretty standard late 77 model 260z 2+2.
It has a very low genuine 50,000 mile on clock.
She goes pretty well on 240z carbs with stacks inside K&N filters.
Manifold is standard into a janspeed exhaust, so I am told.
Would like to add a bit more power!
So just inquiring the best and most economical wayto get up to around 185BHP at gearbox.
Was thinking 6 branch manifold, 1 mm off the head and a stage 2 fast road cam want to keep the 240z carb setup.

Any opinions appreciated.

Cheers
Andrew
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Leave it alone and spend the money on drinks at Spa. :cheers:

Seriously if it's low mileage and reliable just enjoy it as it is, you'll give yourself loads of grief for a few bhp more.
 

SeanDezart

Well-Known Forum User
Why 185bhp - where does that figure come from ?

Head work, cam, keep the carbs, improve the exhaust manifold. For more sensations with the power gained thereby, go for a lightened flywheel, upgrade your suspension and front brakes.
 

Mr.G

Club Member
if you want to play you got to pay, rarely does noticeable power increase come cheap.

I'd also recommend the steps above.
 

pmac

Well-Known Forum User
Leave it alone and spend the money on drinks at Spa. :cheers:

Seriously if it's low mileage and reliable just enjoy it as it is, you'll give yourself loads of grief for a few bhp more.

Seriously you are a proper killjoy..:smash::smash:
Modifying cars is great fun and very satisfying.:thumbs:
There is no earthly reason why it would cause grief if properly thought out and researched before hand,

She goes pretty well on 240z carbs with stacks inside K&N filters.
Manifold is standard into a janspeed exhaust, so I am told.
Would like to add a bit more power!
So just inquiring the best and most economical wayto get up to around 185BHP at gearbox.
Was thinking 6 branch manifold, 1 mm off the head and a stage 2 fast road cam want to keep the 240z carb setup.

Any opinions appreciated.
My opinion............
You are on the right track already with the Janspeed manifold to match the exhaust.
Nowadays its not the ultimate system but it is still a VERY competent set up for a mildly tuned engine..
Upping the compression ratio to around 10.5 to 1 will help.
Just some mild cleaning up of the inlet and exhaust ports will help. Ie mild porting
A modified cam will be usefull too.
sean's suggestion of a lighter flywheel is good . although it doesnt make any more power it allows more power to be transferred to the rear wheels.
the late 260Z head already has the 35mm exhausts and has proper hard valve seats too.
IMO IMO IMO
 

andrew muir

Club Member
Don't worry I shall be taking plenty fluids at SPA.
No this is to get an idea for some work I plan to do next winter.

Leave it alone and spend the money on drinks at Spa. :cheers:

Seriously if it's low mileage and reliable just enjoy it as it is, you'll give yourself loads of grief for a few bhp more.
 

andrew muir

Club Member
Thanks Sean
The 185hp comes from what I believe to be a suitable HP increase that will be noticeable on the road, while still maintaining reliability and driveability. Will not overload the suspension and brakes and chassis. I drive the old girl pretty hard as is we have some great roads up here in Scotland.
Just want to know what is required to get the power up to this level?

Andrew
:)


Why 185bhp - where does that figure come from ?

Head work, cam, keep the carbs, improve the exhaust manifold. For more sensations with the power gained thereby, go for a lightened flywheel, upgrade your suspension and front brakes.
 

andrew muir

Club Member
I cannot obviously tell you as it has not been on a dyno.
The power seems to top out at between 5500 -6000 revs so I suspect about 150BHP at crank.
It certainly pulls similar speeds to my mazda 6 up steep hills and that is a modern engine with a claimed 165bhp.

Andrew
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Seriously you are a proper killjoy..:smash::smash:
Modifying cars is great fun and very satisfying.:thumbs:

Ok point taken but Andrew has a good standard low mileage 260 2+2.

If it was me I'd try and find a good 280ZX engine first. Then if required the original engine could go back in when sold.
 

Ian Patmore

Well-Known Forum User
As you maybe having the engine apart, could replace the dished pistons with flat top ones, which is an Nissan item as far as I am aware

we have some great roads up here in Scotland

Oh yes!, this where I come to play, around where I used to live.
 

zedhead260

Well-Known Forum User
I cannot obviously tell you as it has not been on a dyno.

It could be a starting point, just to see what you have - if nothing else you'll be able to compare a before and after.

The first few hp are the easiest. I think a decent tubular manifold is a must; you could cobble the Janspeed to it but depending on budget you might want to replace the whole system - DJS30 is selling some nice options off the shelf with optional centre box should you not want it too load.

I'd also consider cold air induction. It's not something I have seen on stock(-ish) engines but will work well. MJP sell a fibre-glass box, all you need to do is cut the back-plate to suit your carb's, fit some ducting out front with a big filter in front of the rad-support panel.

Electronic ignition, decent leads (Magnecor) and correct NGK plugs will help it run nicer. An electric fan is an easy gain too.

:)
 

andrew muir

Club Member
Agreed the first few HP's are the easiest.
Just about to order ignition as it is still using points, what the opinion of the pertronics ignition?
Would probably go the whole exhaust route/header route although the standard is suposed to flow well.
Now an electric fan is definately an option I will go for, how much HP is lost through oringinal item 1-2 Hp?
Not so sure about the cold airbox it looks a bit MAX power to me, prefer an older look.

Thanks for input.
Andrew

It could be a starting point, just to see what you have - if nothing else you'll be able to compare a before and after.

The first few hp are the easiest. I think a decent tubular manifold is a must; you could cobble the Janspeed to it but depending on budget you might want to replace the whole system - DJS30 is selling some nice options off the shelf with optional centre box should you not want it too load.

I'd also consider cold air induction. It's not something I have seen on stock(-ish) engines but will work well. MJP sell a fibre-glass box, all you need to do is cut the back-plate to suit your carb's, fit some ducting out front with a big filter in front of the rad-support panel.

Electronic ignition, decent leads (Magnecor) and correct NGK plugs will help it run nicer. An electric fan is an easy gain too.

:)
 

SeanDezart

Well-Known Forum User
Thanks Sean
The 185hp comes from what I believe to be a suitable HP increase that will be noticeable on the road, while still maintaining reliability and driveability. Will not overload the suspension and brakes and chassis. I drive the old girl pretty hard as is we have some great roads up here in Scotland.
Just want to know what is required to get the power up to this level?

Andrew
:)

Just finished a 240Z (eh pmac ;)) in blue with a nicely built std bottom end, lightened flywheel, worked head (10.5) and cam on std SUs giving approx 165bhp at the crank and you DEFINITELY notice the difference.....but then limos weigh more eh ?:D
 
Agreed the first few HP's are the easiest.
Just about to order ignition as it is still using points, what the opinion of the pertronics ignition?
Would probably go the whole exhaust route/header route although the standard is suposed to flow well.
Now an electric fan is definately an option I will go for, how much HP is lost through oringinal item 1-2 Hp?
Not so sure about the cold airbox it looks a bit MAX power to me, prefer an older look.

Thanks for input.
Andrew

If you do decide to go for a pertonics, have a look on American ebay, even with shipping/duty they work out a good saving on UK price.
 

andrew muir

Club Member
Hi Sean
Only 140 Kgs more, I'd better go on a diet then.
As compensation they handle better!?
Andrew

Just finished a 240Z (eh pmac ;)) in blue with a nicely built std bottom end, lightened flywheel, worked head (10.5) and cam on std SUs giving approx 165bhp at the crank and you DEFINITELY notice the difference.....but then limos weigh more eh ?:D
 

pmac

Well-Known Forum User
Not so sure about the cold airbox it looks a bit MAX power to me, prefer an older look.

Nissan used a cold airbox originally. it was red and made of metal. If you dont like the modern version then fit an original one.
whatever you do bin the K+Ns as they will just be sucking hot air into the engine.;)
 

SeanDezart

Well-Known Forum User
whatever you do bin the K+Ns as they will just be sucking hot air into the engine.;)

Hardly relevant as he's not looking for the last 1.2333 recurring bhp !:rolleyes:

No,they don't handle better imho (although there is some argument - not proven) that they do - can't say that I've seen enough 2+2s on the track to say either way? They might be better on the road but go look at the 2+2 here :

http://www.datsun-france.com/ ................:thumbs:
 
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