quick question im getting ready to put a fully built ls-vtec 13.5.1 comp motor into my ek and i was wondering can i just run 93 octane or would i have to run race gas like cam2? the motor has about 3000 miles on it already. my old motor setup was 12.5.1 and i broke it in with race gas mixed with 93 octance and after it broke in i ran 93. so can i do the same with the ls-vtec 13.5.1 comp motor

 

I've got 'more than a feeling' that 13.5:1 on 93 oct in Boston is '"knocking" on heaven's door'; at higher elevation with thinner air it might work (with proper tuning, of course).

 

you can use any gas. depends on what you want for power. the gas will limit how much timing you can run.

 

If you want to drive the car for more than a couple weeks/months......Race Gas.

Jesus, that's a lot of compression to think you can run on 93 octane!

 

what cams are in the engine?

 

you can run it but I wouldn't tune on anything less then neptune or s300. If it's a daily driver then i would add a big remote oil cooler in the bumper and a bottle of water wetter in the rad. in the end 93 isn't the right fuel choice for the compression. maybe 110

 

Sure pump gas will work fine. E85 pump gas that is

 

running on pump gas is a negative, i dont even like 12.5 on pump gas even though it can be done

 

e85 or 110+

Any version of 91-93 octane is just asking for trouble

 

I've done 12.5:1 - 13.5:1 many many times on B20 VTECs with stock sleeves. Its totally doable you just have to be much more carefull with your fuel and timing. But its totally doable. You need to find a tuner with experience tuning this type of setup.

 

Then, the operative question is "WHY?!" Especially when you'd have to run such retarded timing that the car will be weak.

Why not reduce the compression and run more timing....and make more power with better reliability?

 

the motors generally made 220HP+ on pump gas.. I don't think thats considered weak.. Thats on stock rods/sleeves..

 

The key is in the engine preperation. Then NOT tuning it to the edge.. What alotta tuners will do is start out with the base timing map in hondata or neptue or ectune and just tune the fuel first.. That will most times cause detination right away. On those setups I'll start by pulling 4-6 deg globally out of both high and low cam maps, then start tuning fuel.. Once fueling is where I want it I'll very slowly start putting timing back in. Works pretty well. Back in the day we were building this setup left and right.. Basic.. Stock B20 Block, CP 12.5:1 pistons, stock rods with arp bolts. JG manifold, big throttle body.. B16 head with valves springs and retainers, and skunk2 stage 2 cams. If a GSR head was used the compression ended up being a little higher.. These setups made 220+ consistantly on 93 pump gas.

 

its fully built sleeved block port and polish head. jun valves springs and retainers, buddy club stage 5 cams...theres a long list of parts so what about 93 octane mixed with race gas? thats what i did with my 12.5.1 comp motor and it ran fine..but i know its going to different with this motor because everything is different

 

well actually im in upstate ny now i never updated my location..

 

im running hondata s300

 

13.5.1 is over kill on pump gas. i side with C_Rock77 here. your gonna have to back timing off alot or bleed some of the compression by moving the cam gears around. u can make around the same power probably on 12.1 compression which is even high for pump. def would like to hear some input on the subject from a good tuner.

 

what is the cylinder pressure of 13.5 comp enegine vs. a turbo motor with 400whp 9.1comp and 20psi. can you still run pump gas :p

 

how much of a gambler are you? That is stacking the odds against you. Tune it to run on e85. don't waste money on race gas when you can pump e85 into it. You will prolly need bigger injectors that what you have i'm guessing though.

 

ya but what does your timing look like up high on that boosted car :p

 

you already did hear input from a good tuner.

i'm running a little more timing that a stock h22 uses and im above 12:1 (currently running a peak of 33* actual timing). It's all about finding a tuner that takes the extra steps to make sure the engine is working as efficiently as possible but not to the edge. This takes a lot of time and you will pay good money for the tuner to sit behind the laptop or your engine will not last.

 

if would be nice to hold 20psi at idle

 

prolly around 17 or so depending on the setup.

i would think 9:1 compression with 20lbs would be more pressure than 13.5:1.

not sure how to calculate the 20 lbs but heres my math:

9:1 - (9^1.3)X14.7+20=603psi (cylinder pressure)

13.5:1 - (13.5^1.3)X14.7=433psi (cylinder pressure)

by this you cant really compare 9:1 on 20 lbs and 13.5:1 all motor.

correct me if im looking at this wrong. or if the math isnt right.

 

so which is better? the 13.5:1 NA or 9:1 with 20lbs of boost?

 

boooooossssst, but this is the na forum