Looking for a little more power (l24)

[Juarez88]

Hi

 

I have a 73' 240z l24 engine with S.U carbs(not flat top), E88 head and N33 intake manifold. My goal is to try and gain 30-50 more hp and any torque if possible with a budget of around 1000.

 

So heres what I intend on doing, im still learning, so correct me if im wrong. I did some searching and read that it may be possible to gain 5-10 hp more by using a N36 intake manifold.

 

I plan on getting hold of a N36 intake manifold, putting in a twice pipes exhaust system, and a msa 3 into 2 headers. I'm still reading, but im also considering putting on some k&n air cleaners along with carb air horns and getting the su carbs power tuned.

 

 

 

hehe im probably way off here and could be very wrong. Is there anything else im missing out? or wrong on? if any of you have any suggestions please let me know.

[510six]

What I would do is to find a L28 and put a header and use your modified stock carbs.With a mild cam a friend with a bone stock L28 and different needles in the SU`s and a mild cam ran 14.6 on a set of sticky street tires.It was a budget setup, but worked quite well.

[Juarez88]

thats an easy solution(inexpensive) but getting hold of l28 could take alot more time and swapping it. I wouldn't want to swap in an engine im not ready for, and if im going to swap in a earlier engine i might as well swap in a lsd 5 speed tranny while im doing all that work (Im just not ready for any engine swap at the moment). I just want to add some more power to the engine meanwhile and have fun with what I have before I do anything big. That, and I would like to keep the l24 and just use it till it gives out.

 

Would adding those things add the power i want though? Also, since l28s are brought up, would it perform as well as a l28 with SU's with a mild cam, or better?

 

I read some stuff in a couple of other threads of some people wanted to modify their l24s and it seemed like the responses people gave them was kind of like beating a dead horse. Most people just suggesting giving up on the l24. Maybe it is in a sense, but if theres power there i'd like to get it and have fun with an old l24

[ezzzzzzz]

I'd probably drop in a moderate street cam, 3-2-1 headers (I prefer tri-y design for the street to gain bottom end torque), 2.25" exhaust (maybe 2.5"), N36 manifolds and do some simple port matching. The twin pipes won't help with exhaust scavaging. You should reach your goals and stay close to your $1000 budget.

[madkaw]

You'll find on these forums that everyone has an opinion on what works and very little people mess with the the 2.4 block. Yes, 280 blocks are abundant and relatively cheap and displacement is easy horsepower but not that much. Unfortunetly your head that year seems to be the less desirable for hotrodding but you should have the bigger ex. valves which is good if that is the case. I believe your going to have to cam that head to take advantage of the header and carbs. I believe the combustion chambers are not the best and need to up the cr to get a litttle more punch.

I am in the process of doing my 71 2.4 but I have put a LOT of effort to get more ponies (lots of cash too). 12 sec norm had good luck with his 2.4 but you will find not many folks have really massaged the 2.4 as much as the 2.8. I think the folks that have ,have been happy with there motor.

search on zcar.com for 2.4 too.

[JMortensen]

The 2.8 should be a 15% bump in displacement over the 2.4, so a 15% increase in power assuming the engines were built the same. You're not going to get anywhere near a 15% increase out of twice pipes or those crappy 6-2 headers that MSA sells.

 

I'd look at these mods in this order:

L28 swap

cam (if you're looking at MSA, at least stage IV)

Electronic ignition

MSD

exhaust from collector back

header (a good one will take up a lot of your budget)

[johnc]

Actually, comparing ITS spec L28s and L24s you'll find that the L24s make more horsepower but less torque. The L24s are typically spun to higher rpms which gives them a better horsepower number. There is a replacement for displacement, and that's rpm...

 

Getting 50 more horsepower out of any NA L series engine through bolt ons is a pipe dream. You have to at least bump that came up to something around 280 duration, which requires intake and exhaust changes. And a good header (the Nissan Comp one) will burn up 50% of your $1,000 budget.

 

Personally I wouldn't focus on a horsepower number. Take what you have and make it run perfectly - compression check, valve adjustment, carb tuning, ignition, etc. Then start your modifications with the exhaust system. A 2.5" mandrel bent exhaust with new head pipes up to a ported and opened up stock exhaust manifold will help. Add some ITG or K&N air filters along with some heat shielding between the carbs and the exhaust manifold. Swap in the N36 manifolds if you can find them easily, otherwise just clean up and port match the manifolds you have (do the same to the N36s if you get them).

[JMortensen]

Why not spin the L28 faster? They have the almost identical cams, and it's not going to shake the L28 to death to get the extra rpms. Probably has to do with the crappy stock induction system. I'd be absolutely shocked if an L28 with SU's didn't put out significantly more hp than an L24 with SU's.

[spotfitz]

I have an N36 intake minus the balance tube I'll sell you.

[Tony240ZT]

Why not spin the L28 faster?

 

From what I've read and witnessed the longer stroke on the L28 makes it difficult to rev as easily.

 

I had a L24 with a P90 head that I turboed with an EFI system, then took the exact same turbo EFI system and head to put on a F54 L28 bottom end and the quick light reving experience that I had before went away. But I gained a lot of low end and mid rang torque that was noticeable by the seat of the pants. Also, the exhaust note was different, more throaty sounding. Also the rods on the L28 were shorter. Without my books infront of me all I can remember is that longer rods have some advantages because there aren't as extreme of angles.

[ezzzzzzz]

My suggestions were for more realistic gains in the 20-25hp range. Even that would feel significant over bone stock. Since it appears he isn't wishing to jump into a motor swap then these would be his next alternative. There is no replacement for displacement though....

[johnc]

Why not spin the L28 faster? They have the almost identical cams, and it's not going to shake the L28 to death to get the extra rpms.

 

In my limited experience, having driven ITS prepared L24s and L28s, my guess is the cam and valve springs are the limiting factor for both engines. From what I understand they are close to identical but going much past 6,700 in an L28 is an exercise in noise and flatness. A L24 can go to 7,000 before I get the same feeling.

[Challenger]

How much is a Megasquirt system and if paired with a better fuel injection intake manifold what power gains can you expect?