What would be the possible outcome if I built this motor and ran it on a stock 1995 obd1 computer? Not looking for street ability, this is an off road car.
11.5:1 cr, mild p+p, cam regrind, 1.6 rockers, +1mm valves, hybrid lifters, mild port on intake, and 110 race gas.
This would also include stock throttle body, injectors, exhaust manifold, air box (modified) short 2 1/4 exhaust w/ muffler and no cat.
Just wondering what can be expected w/ this set up on a factory tune? Thanks
You might still have knock with that high compression even with the race gas. I hear the higher compression affects the OHV engines a lot more than the DOHC engines. I have yet to get an explanation why but thats what the OHV gurus round here have told me.
Also you wont see the power from the mods with a stock fuel table, you need tuning to utilize those mods. It will still be noticable but you will not see near the power of a tune. Plus im thinking its gonna run with those mods.
Zs Z wrote:You might still have knock with that high compression even with the race gas. I hear the higher compression affects the OHV engines a lot more than the DOHC engines. I have yet to get an explanation why but thats what the OHV gurus round here have told me.
Also you wont see the power from the mods with a stock fuel table, you need tuning to utilize those mods. It will still be noticable but you will not see near the power of a tune. Plus im thinking its gonna run with those mods.
I think the issue related to knock stems from the air-flow characteristics and how much more critical a good mixture is when you reach those higher compression ratios:
1. OHV - 2 valve has more of the valve area shrouded or blocked by the cylinder wall - at higher rpm these heads don't flow as well and your intake charge can be diluted by exhuast gases still in the chamber.
2. OHC - 4 valve has less valve shrouding effect, spark plugs centered in the combustion chamber, geometry allows for flatter combustion chamber design and a lot of squish area to better mix the fuel just before spark, and better flow in the mid-high rpm range.
3. If you can't always get your high octane fuel, you'll have to use a lot of spark retard and your engine will be down on a lot of power. Not to mention, lots of spark retard can lead to more engine knock as it tends to keep exhuast valves glowing hot which can lead to pre-ignition and more knock....
just some thoughts....
one more thing - the J is little heavy and the gearing is not very tall, so you may tend to lug the engine more - this can be hard on high compression engines - I think because mean cyl pressure is higher longer.
