Wanting to get about 200HP from L24

[240tim]

Hi All,

I am about to pull the engine out of my '72 240Z to give it a complete rebuild, while it's out I would like to modify it a little to get a bit more performance. My target is 200HP at the flywheel, nothing too crazy. If anyone could give me some advice on whether this is possible and what modifications I would need to do I would appreciate it.

There are a few things I wont change such as the displacement as I feel that as its called a 240Z it should have a 2.4L engine. Also I want to keep it NA and carburetted.

I have read that porting the head and installing a more aggresive CAM will give good gains. I still want to be able to use it as a daily driver however.

Thanks in advance for any help.

[nzeder]

How much are you planning to invest in your goal of 200HP at the fly?

Given what you have stated I would say the HP figure is not that important but more the seat of the pants feel and punch the car can deliver. Would this be correct?

What is the rest of the car like to drive? By this I mean is the suspension standard, rim size and tyre sizing etc. My 260z when I purchased it some 17 years ago was on stock L26 and stock L26 SU carbs and stock suspension. The best improvement I did was suspension. Without doing anything to the engine the car was transformed. I would recommend doing this first then the engine after that.

However if the engine is on it last legs and is coming out for a freshen up then I guess while you are at it you could improve things a little however sticking with the stock bore of 83mm will limit the amount of work you can do on the head and that is the area that will yield most gains. Triples, good headers (tuned equal length if that is your budget), and a cam will go a long way. Now having said that some new needles and rebuilding your stock 240z SU will be more than up to the task they just won't give your same feel as the triples (ie throttle response). Again the SU will do the job for the HP you are looking for and them some if setup correctly. Also the stock exhaust manifold flows very well so that does not have to be changed. You change it for a little weight saving and a different sound - but then be careful of some headers their design can make the car drown at mid RPM.

Lots that can be done and again most of this does depend on the budget you have in mind.

Hope some of this is of use.

Cheers
Mike

[240tim]

Yeah i'm not dead set on making 200HP. I just thought that would be a realistic goal and make the car just that little bit more fun to drive. I'm willing to spend quite a bit, but as this is my first ever engine rebuild and considering the difficulty of finding performance parts I don't really have a clue of the costs involved. If you could throw me some rough figures that would be great.

As for the rest of the car, lets just say its very much a work in progress, I've only driven it very slowly 4 times. The longest distance being about 10k's. The suspension is completely shot so I haven't yet experienced the great handling of a Z car. But I'll get there one day. I figured since I am taking the engine out to strip and paint the engine bay I shoud do it all at the same time. So I don't have to do it again. I don't think the engine has ever been rebuilt.

What sort of figures do you think I could get with Triples, a street Cam and headers?

Cheers
Tim

[nzeder]

What sort of figures do you think I could get with Triples, a street Cam and headers?

Cheers
Tim

Sounds like a good bit of work ahead of you then Tim.

I would recommend not tipping to much into the engine then thus allowing more $$ for other areas that also benefit from investment (ie suspension - this will give you that fun to drive when mated to a strong L24)

Triples - depends on brand and size but for a L24 then 40mm Mikuni are a good fit (some don't like the mikuni's but they have advantages and disadvantages) the disadvantage of Mikuni's is source for parts. Wolk Greek Racing in the USA is a good place to get jets, rebuild kits and the like from. Then there is Dellortto and weber.

Cost of these will be anything from $1200-1800 and most will need a good check over and lower priced items some cleaning/rebuilding. You will also need to choke and jet correctly for your setup. You should also switch to an electric fuel pump and remove the mechanical items from the side of the head.

Headers $500-1000 for new items from Custom Chambers - depends on which of his models you get - just the header or the turned header.

Cam would be best to talk to a cylinder head shop about your requirements - ie pump gas, good pull from 2000-4000rpm etc they can best help you with the setup/flow. You can drop anything from $1500-5000 on head work but given your goals that would be the lower end $1500-2000 - but again that is just a guess been a few years since I have had any work done on a L6 head and that also depends on what needs to be done to the head ie new valves, seats, welding etc

So that would be $3200 before you looked at the bottom end for new bearings, hone, rings and a gasket set (assume pistons/rods/crank are good and don't need changing/repairing) and also balance the rotating mass = more power right there if all correct.

Hope that helps.

[us2]

240tim If your suspension is shot, and most likley the brakes as well, listen to Mike and do some work on these areas first.
Our bog stock engine on our 240 has done 120,000 miles, uses no oil, and is still capable of giving me a few thrills. To me, being
able to handle a corner at twice the recommended speed can be exciting enough, and stopping before you run up the bum of the car ahead,
or run over some child on a crossing. Tighten up the suspension, get it on a twisty backroad, and give it a thrash around some nice corners.
You might be pleasantly surprised. You don't need gobs of power to enjoy the drive. I once had a 1300 Corolla station wagon that I used for work.
That little underpowered thing on a twisty road was a blast.
:

[classicdat]

http://www.trademe.co.nz/Trade-Me-Motor ... 806845.htm
I'm sure these were on at 1500 the other day, but sound like a good match for your plans.

[merlin]

Hi 240Tim
I had my 240z engine rebuilt a few years back by a guy in Hamilton. He mainly did it for the love of the L series engines so I got a great deal. I had the head ported, new cam grind, lightened flywheel, 280z valves fitted, 40mm dellortos carbs. balanced bottom end, lightened rockers and 6 into 1 headers fitted. It has been dynoed and produced 192 hp @ flywheel and around 148 @ wheels. Its still fairly driveable around town but really likes to have a good blat on the back roads coz the cam doesn't really cut in till 3500rpm.
It is not too bad on gas either (Auckland to Hamilton and back on 1/6th of a tank if I am being kind to it)
I would get the brakes and sus sorted before any engine mods.

[240tim]

Thanks for all your help guys. Will definately be getting the rest of the car sorted first, just wanted to know if 200HP was even possible. Long way to go before I can take it for a blast on a country road but I'll get there. Can't wait.

[nzeder]

Thanks for all your help guys. Will definately be getting the rest of the car sorted first, just wanted to know if 200HP was even possible. Long way to go before I can take it for a blast on a country road but I'll get there. Can't wait.

to answer the question "just wanted to know if 200HP was even possible" well big mods and 380ps at the flywheel in NA form is possible and 100HP per 1000cc at the wheels is do able if budget and mod permit so 2400cc is capable of 240HP at the wheel and I know of L24 in Australia that is making such numbers for the Historic SC racing class.