New rebuild, compression issues, got questions.

[RILS]

when i stated 225psi, i was talking about my 1993 Honda Prelude H22A1 2.2L DOHC VTEC 4 cyl motor, its stock compression is 10:1 and i just checked the compression and the max i saw on one cylinder was 225psi, it was from 217 to 225 on all 4 cylinders. and i spoke to other people on a honda forum where its a well known place and most H22A owners run 190 to 230psi and those motors run on 93 octane, why cant 2 stroke run on pump gas (93 octane) above 160psi?

 

I've built Honda auto motors before a few times and those psi are about right.

Do as you wish.Go ahead why stop at 160 or 180 hell run 225 or 500 or whatever run it on 87 if you want ,I was just tring to give you some advice to help you out and save your motor in the longrun.If you can run these ratios with 93 more power to you.I will be willing to bet a few years from now you will be real good at rebuilding a motor because you will have a lot of expercince with this setup.If you dont beleave me take a poll from everybody here.

[dlnoss]

There is quite a difference between a 4-stroke and a 2-stroke engine,,,paricularly when the 4-stroke is fuel injected and computer controlled. Some engines can survive a lot of detonation. A 70's era pickup truck can knock all it's life without necessarily damaging the engine. A Banshee engine doesn't live long when it's detonating.

 

Some two strokes can do fine on 93 octane with and 180 psi. It depends on the timing, the RPM, the combustion chamber design, and other factors.

 

I run 104 to 110 octane and only have 175 psi. but that's just me..

Edited June 10, 2006 by dlnoss

[RILS]

There is quite a difference between a 4-stroke and a 2-stroke engine,,,paricularly when the 4-stroke is fuel injected and computer controlled. Some engines can survive a lot of detonation. A 70's era pickup truck can knock all it's life without necessarily damaging the engine. A Banshee engine doesn't live long when it's detonating.

 

Some two strokes can do fine on 93 octane with and psi. It depends on the timing, the RPM, the combustion chamber design, and other factors.

 

I run 104 to 110 octane and only have 175 psi. but that's just me..

Thanks Dave.

[Walleye]

Do as you wish.Go ahead why stop at 160 or 180 hell run 225 or 500 or whatever run it on 87 if you want ,I was just tring to give you some advice to help you out and save your motor in the longrun.If you can run these ratios with 93 more power to you.I will be willing to bet a few years from now you will be real good at rebuilding a motor because you will have a lot of expercince with this setup.If you dont beleave me take a poll from everybody here.

 

 

yea i was just trying to clear some things up about difference between 4 and 2 stroke, but now i just realized after reading dlnoss's post, i just completely forgot that 4stroke motors usually have o2 sensors, knock sensor and such so that helps the motor to maintain proper tune at desired octane depending on cr.

 

that was what i was looking for because i wasnt thinking abt that before. but now its all good.

 

ill just ride it out now and check it after a tank. so 130 psi is reasonable for my setup?

[RILS]

yea i was just trying to clear some things up about difference between 4 and 2 stroke, but now i just realized after reading dlnoss's post, i just completely forgot that 4stroke motors usually have o2 sensors, knock sensor and such so that helps the motor to maintain proper tune at desired octane depending on cr.

 

that was what i was looking for because i wasnt thinking abt that before. but now its all good.

 

ill just ride it out now and check it after a tank. so 130 psi is reasonable for my setup?

Yes i would say that 130 is reasonable.If you decide to go higher like 180 you will see big gains in the lowend but will lose a little on top.Im running 18cc and 180 psi and expercing some things in the transition from mid to top.Im not sure if its in the jetting or the compression is slowing my rev.Im tring to find some used 19 and 20cc domes to experment with.Im also going to try a vitos needle not sure which first just depends on how quick i find the domes.

[Ben350]

they are right. in car motors timing is constantly being changed while you drive depending on a variety of inputs{TPS,knock sensor,MAP sensor,etc}. Also they use other methods such as EGR to reduce combustion temperatures and avoid pinging and detonation. If every shee engine builder and every person on here says that 145 is the max on pump gas i would believe them. I think they have a tad bit of experience

[BlkLT1Z28]

180 psi is not 10;1 its more like 12.5;1 and its not allright to run a honda at225 thats over14;1 on 93 go to your nearest race track nascar dirttrack dragstrip or anything even your local grease monkey and see how many of them run 93 on a motor with that kind of compression.I didnt say it wouldnt run i said it will damage it and it will spark nock "ever heard of this".If it was ok you would see the whole nascar field filling up at the local bp instead of hauling aroun sonco and all the other expensive race fuels.

 

 

You can not compare PSI to 10:1, 11:1 etc. Its not the same. There is no rule saying this many PSI equals this much compression. My LT1 in my Z28 is a 11.7:1 motor but I bet my cranking PSI is about 120. How is this? My cam has a lot of overlap.

 

A 4-stroke is a lot different than a 2-stroke(obviously). A banshee, 250r, or whatever might have 130PSI when you kick it with a gauge on it, but think what it might have at WOT. Everyone here says 150 is the limit with 93 anything more than that is playing with fire, why not believe them. Remember your Banshee doesnt have a computer, knock sensor or any other little things that can tell when somethings not right like my Z28 or your Honda does, it will just run untill it blows.

 

Can you afford to be stupid and ignorant?