12:1 compression

[bigz-71]

If i open my motor up and put a 12:1 compression piston in it, will i have to run race fuel or can i still run pump gas?

[CHEVYZ]

Pump is fine! The 06s come stock with 12:1......

[ricks450]

from what everybody says on this forum is yes you can run pump gas. i know they run 12 to 1 in the 06's but i dont know how much honda advance the timing neither. you can run all the compression you want on pump gas as long as you retard the timing enough, which defeats the whole purpose of running high compression. from my experiance 12 to 1 is to high to run on pump gas on almost every motor ive built. but they have got cylinder heads now that have expansion cambers that will allow you to run pump gas on higher compression (not to high) to help eliminate pre- ignition or pre- detonation. which ever you prefer to call it. to be safe from what ive learned my whole life building differant motors. i personally would run cam2 or sunnco 110 race fuel to be safe or lower your compression alittle. its hard to listen to a motor and hear spark knock if its not doing it hard enough. it will cost you a motor if its doing it and dont know it so i personally would be safe and run race fuel. :)

[ricks450]

Originally posted by ricks450
from what everybody says on this forum is yes you can run pump gas. i know they run 12 to 1 in the 06's but i dont know how much honda advance the timing neither. you can run all the compression you want on pump gas as long as you retard the timing enough, which defeats the whole purpose of running high compression. from my experiance 12 to 1 is to high to run on pump gas on almost every motor ive built. but they have got cylinder heads now that have expansion cambers that will allow you to run pump gas on higher compression (not to high) to help eliminate pre- ignition or pre- detonation. which ever you prefer to call it. to be safe from what ive learned my whole life building differant motors. i personally would run cam2 or sunnco 110 race fuel to be safe or lower your compression alittle. its hard to listen to a motor and hear spark knock if its not doing it hard enough. it will cost you a motor if its doing it and dont know it so i personally would be safe and run race fuel. :) not saying everybody is wrong but a $1000 for crankshaft and top end that is stock is to much money for me to find out. so i just would go with what i learned and run race gas and race gas isnt going to hurt it even if it dosent need it.:)

[bigz-71]

so would you recommend running race fuel 100% or mixing it 50%?

[honduh440]

u can run pump no problem at all ive seen a million people do it

[ricks450]

a 100% because its easier, and you dont have to buy both fuels.:)

[bigz-71]

so how much is race fuel running these days? Per gallon or per five gallon?

[ricks450]

its about $5.20 a gallon around here. yes its alittle pricey but thats what going fast is all about. theres away to stay away from race gas, but it cost alittle bit to do. and thats going up in your bore size (CC's big bore kits) and staying low compression. that the same thing as going high compression. but of course if you go high compression and bigger bore you will make more HP. but it sticks you running race fuel. most of the big bore kits that you can get are high compression but if you call duncan racing they will do your head so you can run high compession piston and run pump gas. but its like $495 i think to get them to do that. along with your bore kit. thats $1500 right there. thats alittle high for my wallet right now. thats why i just said the hell with it. im running cam2 which is 110 octane race gas. im going 500 12.5:1 compression.:muscle:

[bigz-71]

so duncan racing sells a 12.5:1 piston. all i coud find when searching the internet was 11.5:1 or 13:1. i guess if i want power i am going to have to pay for the fuel too. Well i need to find a local shop that carries it around here.

[ricks450]

weisco sells a 12.5:1 piston std bore. but they also sell a 500 bore kit with a 12.5:1 piston in it to, thats what im getting. some BP gas stations sell cam2 right out the pump so i would check there.:)

[bigz-71]

thats cool. i want to stay stock bore right now 449cc and not any bigger.

[ghott]

12.5:1 Compression ratio and under is O-K for 93 octane pump gas.

Anything over 12.5:1 Static compression ratio....it is suggested that you use race fuel, or a mix of race/pump fuel.

These small 450cc engines are MUCH different than a standard V6 or V8.

We are able to run much more compression on pump gas safely without any timing advance or retarding.

[bigz-71]

Well i guess i still have questions about this subject, what brand of piston or are they all about the same? i was looking at wisco or JE pistons but did not know if one was better than the other.

[ghott]

Wiseco pistons are nice pistons...very cost effective...cheap. They are a bit heavy tho. $140 on eBay :).

JE is Wiseco's "high performance" brand. They will be a little nicer than normal Wiseco pistons...and a little more pricey.

CP brand pistons are of very high quality. They actually make a 12:1 stock bore piston for the 04/05 450R. They are around $200

Good luck!

[Smidgy]

I love this topic, it seems someone starts one up about this every other day. Everyone seems to think that if I can get by with 94 octane then if I use 100 or 110 then I am even better off....wow is this ever wrong.

[ghott]

Originally posted by Smidgy
I love this topic, it seems someone starts one up about this every other day. Everyone seems to think that if I can get by with 94 octane then if I use 100 or 110 then I am even better off....wow is this ever wrong.

100 or 110 octane will provide even more detonation resistance....so I wouldn't call it "wrong."

But it will be MORE EXPENSIVE for the purchaser :).

[GPracer2500]

In addition to what ghott mentioned, a racing fuel is going to be consistent batch to batch. Jetting consistency can be reason enough to use a racing fuel.

You can't "over octane" an engine.

[Martin Blair]

I have a JE 13:1 i run on pump gas when were out and I can't find race, it runs fine, but it might have something to do with the stage 2 hotcam, actual compression could be down from 13:1. When I get around to puting my motor back together, Im going to go with the 14:1 baldwin, which wil require race.

I don't believe JE has any affiliation with Wiseco, but I may be wrong about that

[Martin Blair]

Originally posted by Smidgy
I love this topic, it seems someone starts one up about this every other day. Everyone seems to think that if I can get by with 94 octane then if I use 100 or 110 then I am even better off....wow is this ever wrong.

I know allot of people who think higher octane race fuel will damage their motor, this is a common misconception. The only scenario I could think of it being a problem is on a really, really cold day the motor may not get to proper operating temperature.

[Smidgy]

I never said that it was going to damage their motor, I said that they would be wrong by using this and thinking they are better off, basically you are wasting your money, i mean sure go a little overkill but there is no need for most of these people running 110 to be running it. In a lot of cases 100 is plenty

Detonation resistance is a bad sounding way to put it, because it gives you no real resistance, but I understand what you are saying, it will not detonate prematurely. As you said it is just a very expensive way to have peice of mind, IMO, especially when you don't need it, and it is providing no benifit if it isn't necisary.

You can over octane an internal combustion engine in theory, but luckily it takes a little more than what is shown in the problems here, for example try running gasoline in a diesel engine, but this would be extreme like going from 25 to 90 in octane levels.

It all depends on what you have for a cam what you have to use, a lot of these kits running 12.5:1 are really only going to be hitting about 11.8:1 or less dynamic compression so they are definately fine to run on pump gas. Just because it says 12.5:1 or 12:1 doesn't it mean it is. Now the 14:1 kits that is a different story now you are into something that is going to require some higher octane, but 100 would be lots.

[ricks450]

Originally posted by ghott
12.5:1 Compression ratio and under is O-K for 93 octane pump gas.

Anything over 12.5:1 Static compression ratio....it is suggested that you use race fuel, or a mix of race/pump fuel.

These small 450cc engines are MUCH different than a standard V6 or V8.

We are able to run much more compression on pump gas safely without any timing advance or retarding. just a qeustion not trying to be a *ss.but what is the differance from this little 450 then a V8 or V6 motors they all cranks, rods and pistons. the only thing differant is the cumbustion chambers. im not talking standard heads neither on V8. you mines well not even build a hot rod if your going to use a standard head without doing some kind of head work anyway.

[ghott]

Originally posted by ricks450
just a qeustion not trying to be a *ss.but what is the differance from this little 450 then a V8 or V6 motors they all cranks, rods and pistons. the only thing differant is the cumbustion chambers. im not talking standard heads neither on V8. you mines well not even build a hot rod if your going to use a standard head without doing some kind of head work anyway.

Bore sizes...the heads...intake and exhaust ports...cam...valve and spring styles....everything in much much smaller...

And our 450R's rev to 10,000 RPM's....

Apples and oranges.

[ricks450]

can anybody explain the cumbustion chambers on the heads. that is on these 450's. can anybody explain the differances from a head that is better then the other. the higher the ratio the more times it compresses the air. the more you compress the more friction the hotter it gets. so the more octane you need so you dont get pre-ingnition or pre-detonation which ever you guys like to call it. my honda civic produced more HP in one cylinder then any of these 450's will produce on 110 octane and it would spark knock on 12 to 1 and with the last V8 i built was a 355 small block 12.5:1 with dart-iron eagale cylinder heads with 202 160 vavles and a 355 306 cam and it spark knocked on pump gas. thats just two out of many. not just car motors neither. so am going to run race fuel in it no matter what anybody says. if i dont need it ol well. i just no i want beat the hell out of my crank and everything else that goes with it. so good luck to all you guys running high compression on 93 octane. i cant aford it to find out myself. not calling you guys dum. but its taking me to long just to get it back together now. i got a 3 week old little boy now. and i just dont wont to whip out $1800 that is going in it now.

[ghott]

Sounds like your questions can be answered by a head porter...

Call up DEE MANSHACK at www.rageatvracing.com

281-593-2481

[ricks450]

Originally posted by ghott
Sounds like your questions can be answered by a head porter...

Call up DEE MANSHACK at www.rageatvracing.com

281-593-2481 i will do that. thanks for the number. i just have done all my own work and never really talked to anybody about the differant cumbustion cambers. i know they have what you call fast burn chambers, that helps with pre-ingintion on high compression (but not to high)but ive heard it can also keep it from deflagrating or detonating which ever you like to call it.:)

[ghott]

Originally posted by ricks450
i will do that. thanks for the number. i just have done all my own work and never really talked to anybody about the differant cumbustion cambers. i know they have what you call fast burn chambers, that helps with pre-ingintion on high compression (but not to high)but ive heard it can also keep it from deflagrating or detonating which ever you like to call it.:)

I understand your concern.

Dee will be able to answer all of your questions in detail...he is a very knowledgeable fellow. He has been building small CC engines for many years. He is actually the engine builder for Pro Rider John Natalie.