D24 performance summary + water injection possibility
 

I just rebuilt the head on my NA D24 and I have gotten good results with it after adjusting the pump right.

I currently have:

Increased fueling a lot. Homemade made tubular headers with 3" downpipe going to a 2" exhaust. Intake manifold casting marks have been sanded down.

I ported the cylinder head. Injection pump timing is currently 0.90mm. I have the stock resonator as the only muffler right now.
I cleaned the injectors with a ultrasonic cleaner.
I matched the exhaust and intake manifold ports to the head the best I could.

The bad:
Fueling too high
Exhaust too small? (2")
Worn engine
Worn injectors
Air box intake pipe not working as a cold air intake
Engine breather hose still connected to intake manifold

I wonder if removing the breather hose from the intake and plugging the hole on the intake and adding a bottle for the breather would increase performance because this engine currently has enough blowby to blow white smoke out of the breather hose if you remove it while the engine runs.

Piston rings don't seem too expensive but don't know if they would do anything if I only put new rings on the pistons? The blowby doesn't show as oil consumption at all.

I currently have so much smoke that there is a huge black smoke cloud if you floor it. I think the next step would be to back off the screw quite a bit because I am afraid to hold the throttle pinned for too long because I fear the engine might get damaged from the most likely high EGTs.

I don't have an EGT gauge and I wonder, how high could the EGTs get with a naturally aspirated engine that is being overfueled? Could the temps actually get high enough to melt the pistons?

I have also realized that the engine is advertised as having max power at 4800 rpm but the rpms climb so slow after 4000 rpm that shifting at about 4200 rpm is a must.
I looked at the governor mod and think I can do it but will this help with a naturally aspirated engine? Would it be able to pull well to over 4500 rpm with the mod and would it cause EGT issues?

I am looking at the possibility of installing water injection to the engine as I've heard this would lower EGT and increase oxygen making it so you can burn more fuel?

I have the setup well understood except I wonder if you have to use alcohol with the water or can you just use water and have performance gain with it?

I have the idea of using a button under the throttle that when throttle is pinned it starts injecting a cloud of water through a nozzle of some sort through where the breather hose currently connects to the intake manifold.

I currently got 0-100 in 16 seconds with the car and believe it can be improved quite a bit.

Currently I got very good low end torque. So much so that the car is pretty much impossible to stall even though 1 gear is rarely used on this car.

My final goal would be under 15 seconds 0-100 naturally aspirated with very little smoke full throttle

Are you planning on entering into competitions that disallow turbo?

The water or water/alcohol injection question is an interesting one.

The goal of doing that (as you undoubtedly know) is to help cool the intake air mass, enabling you to get more oxygen into the engine via a denser intake air charge. However, that is mainly beneficial in the scenario of a turbocharged engine. As I understand it the main reason for that is: the turbo and the pressurization of the intake air create a great deal of heat, so that creates a lot of room for potential benefit from charge cooling techniques such as intercooling and/or water-alcohol injection.

In the scenario of a naturally aspirated engine however, the reasons for doing it would be less clear. Since the intake charge is less hot and more dense already to begin with on a NA engine sucking cool atmospheric air in, there is 1) less heat to vaporize the water or methanol to create a cooling effect from phase change and 2) less benefit to be gained from reducing the temperature of air that's not very hot to begin with.

It sounds like you have already been making great progress with the car but ultimately you may run into a limit as to what can be accomplished without increasing the airflow to the engine. There is a reason turbos are commonly seen on diesels.... they are the best method to achieve that. Porting and other techniques and injection pump tuning maybe (?) can do some good but only up to a point.

If you're at 16sec now with heavy smoke and want to get to 15sec with light smoke, you would need to add a lot more air to the engine. The smoke means your limiting factor already is oxygen, not fuel. A turbo would be the obvious choice but maybe a supercharger would be of interest also?

Thank you for the reply.

I think I will refrain from putting the water injection in that case. Adding the turbo would probably make this engine have very good pull considering the current results. But from the beginning of this project I decided no turbo. I have considered a supercharger but I would need a belt straight from the crankshaft belt pulley because the camshaft is known to be weak on these cars. Also I would have to obtain the supercharger :o

I think increasing airflow with a ram effect for airbox would be the next thing with removing the breather from intake because it basically shoves exhaust gas into the intake which must reduce efficiency.

I read on the forums that governor mod allows the engine to pull to about 5000 rpm good. If that's the case I believe with some other non mentioned modifications it will easily do the 0-100 in 15 seconds. Due to the engine and injector wear, the performance is of course reduced and I can never restore the compression. I have done calculations with percentages and I estimate if the 82 hp it comes with stock is true, I will end up with 105 hp and 185 nm.

No, I am not :p I have been to car meets with my car and people are often shocked that there is no turbo.

I have probably spent too long tinkering with the exhaust for the best sound. It does have an amazing sound and if I had a turbo there would really be no point in tinkering with the exhaust because from my experience it's either straight pipe to get some exhaust note out of the turbocharged D24 or mufflers to not hear the exhaust at all.

If your looking at a super charger you should be able to run an eaton m45 from a Merc with the pulley off of a M45 from a mini for a max boost of 10.2psi excluding valve overlap calculations. (then bleed/bypass to control boost vs RPM). Pulley ratio would be about 2.67 to 1

a crack pully from a VW t4 should be direct fit, then an alternator from a T4 with an over run pully (machine the back of the pulley to make it fit). You would need to find something to then run the power steering.

That's as far as i have got with it anyhow.

Dan