I have tried searching for ideas on improving the knock resistance of our motors, but have not really found a lot. I know the simple answer is to just buy the next higher octane fuel, but some of us don't have that luxury. I put together a short list of some ideas and would like some feedback.

I’m looking for any tips and tricks that might allow me to maximize the use of the poor quality ACN91 fuel I am stuck with. Will any of the following offer any possible benefit?

HIGHER WATER TO COOLANT MIX RATIO – To improve the cooling efficiency of the head.

REDLINE WATER WETTER – Not sure about this product. Some hate it some love it. Again, to reduce head temp. Some say this is bad for aluminum, but we have an iron head and block, correct?

NGK BPR8ES COPPER PLUGS – One step colder plugs might help. Affordable, worth a try. May not help any at my mod level.

DISCONNECT COOLANT LINES TO THROTTLE BODY – Drop the reheating of the intake air. Hopefully lower air temps slightly.

UPGRADING FMIC – Not sure if a larger I/C really adds any power, but I'm sure it does reduce air temps. Saving up for this one already.

1.3 BAR RADIATOR CAP (19PSI, 130 KPA) – Supposedly will reduce potential hot spots in the head. Is this a bad idea on the stock radiator?

WIDEBAND LOGGING GEAR – Should allow for more accurate A/F adjustments. Would do this, but I'm waiting for a simple, small unit that interacts easily with EvoScan.

LOWER ENGINE TEMPERATURE THERMOSTAT – I’m data logging 180*F, so I don’t see much to be gained by a lower temp stat.

WATER INJECTION – I’m not so crazy about meth/alky, although I fully understand the potential benefits. However, I have been considering running straight water injection as a method of increasing the ACN91 knock resistance. Why don’t I see more Evom members who are shy about meth doing this?

Any other suggestions for improving knock resistance? Corrections to this list? Additions?

Thanks,
Jim

 

This is your winner. If you just go with straight water at low volumes and don't try to treat it like race gas you will get great results.

 

alky injections is the absolute cheapest and best way to produce SAFE added gains

 

water is a great knock supressor. alky/meth is a fuel and carry's more risk. it's up to you.

 

Move out of Arizona

 

Better flowing head..port it.

 

If you upgrade the intercooler go for the ETS 3.5, it does wonders in the climate you live in! Tested and proven by me! lol

 

nkg plugs.
a better tune
water or meth injection

those are the only options that will gain you some results.
changing the coolant or thermostat wont help with detonation.

 

water injection could also be a risk if you tune more aggressively due to improved knock threshhold; just like a meth kit, if anything goes wrong, you're left high and dry

Conversely, if you only use water injection for added safety and don't tune more aggressively while on it; you probably won't see any added power with it... Probably only worth your time if you're road racing for prolonged periods

 

Why are there 2 threads with the same text?

 

Cam timing can play into the knock scenario. For example, adjustable cam gears allow you to alter intake valve closure after BDC, thus impacting upon your engine´s dynamic compression ratio and in turn, its tendency to preignite the combustion mixture.

 

EDIT: My Bad.

 

Good question. I dunno???

I deleted the other post.

 

I did the first 3 on my Nissan, and I would consider water injection the best method for your goal.

I ran water wetter in my SR20 for a good 130k miles (aluminum head and block) with no issues. I also used a 1.3 bar radiator cap on the stock radiator, so I'd imagine that the Evo radiator should be fine also; however, this technique was used primarily to prevent boiling and the resulting overheating, not necessarily reduce the coolant temps to a lower level. So I do not think the radiator cap will do much for you.

I've also considered running water injection purely as a buffer because of the crap gas we get in Cali. Get the car tuned to how you like it, and then add the water injection on top to add greater safety margin.

 

Time machine