i'm building a B20/VTEC for a friend w/ 12:1 Arias pistons. its going to be street driven. do you think w/ good tuning i will be able to run it on 91 octane w/out detonation?

 

I tried my best to run 12:1 on 91 octane with stock timing and still pinged. Retrding it to 12 stopped the pinging but made the car slower For something more reliable I would stay at 11:5:1. Maybe with some type of standalone you can run 12:1

 

I am going to run 12.1-12.8 CR Endyn Rollerwave's in an LS/VTEC I am currently building. Detonation is the enemy, so I hopefully will eliminate it using Hondata.

 

we are going to run a chipped P28 w/VAFC. i hope we can get it to run good on 91, if not then the sucker is going to have to drink 100...thanks for the replies

 

12:1 on 91 octane isnt going to work well. i had about 12:1 compression on my ls/vtec setup with "skunk2" program chipped p28. i had to set base timing to about 12-14 degrees to get rid of the knocking. the ign map on that program is about 2-3 degrees advanced in the low rpm areas and about 2 degrees less in the 6-8k area vs a stock gsr ign map. i had slight pinging bewteen 3-4k rpms at about 14-16 degrees base timing.

i would say 11:5-11:8 on 91 octane would be best for a daily driver.

 

id say this guy is almost right on the money. i run 12.5:1 w/skunk2 program, the only time i detect detonation is when im at lower RPMs and give it too much gas. high RPMS dont seem to suffer from detonation. 92 octane here.

 

I would also like to add.. the chance of detonating is more likely in a street driven car. The higher the compression, the faster hotter temperatures will get. So, you can have the recommended 94 octane if you are runnin 12:1, and you can start to detonate down the road ..easily in traffic.

You can dial out timing. It'll be doing 'negative' work, since the timing degree needed might be lower than the stock 16deg btdc. And like Halo said.. it'll make the car slower than before.

There are things mechanically that will prevent the likelyhood of detonation. Deburring to reduce hot spots (rollerwave pistons), better ring lands, coatings, basically anything that improves heat dissipation from heat sources. Running an oil cooler is a plus.

If youre going to run 91 oct, I would recommend no higher than 11.0:1 because of street conditions. Ive seen low compression setups produce as much torque as high compression. It just takes the right timing adv and octane rating. If youre 12:0+, you cant run advance timing. Well, you can but not pump gas.


[Modified by Quick 200k Mile Motor, 2:04 AM 8/14/2002]

 

I'll be running 12.5:1 on pump 94 octane with good tuning.

 

I'm at 11.6:1 on 91 octane, and I had to retard my timing to 14 base. Any more, and it would ping at 5-6k.

Oh, I'm running the XS engineering chip on a stock P72 ECU. Base fuel of 48.

 

I run 12.1:1 with 94 octane and I have no pinging problems. I am using Hondata, but I have never had any problems with detonation even with the basemaps.

 

That's good to know because I will be running 11.8:1 with a Hondata.

 

i know you are asking about 12:1 C/R on 91 octane, but i can run stock timing on 93 octane fuel with 11:1 C/R and absolutly no problems as of yet.

i'd stay between 11:1 and 11.5:1 if you want to use 91 octane and close to 16 degrees timing. or you can go the higher octane route or Hondata programming.

later