sxviper-s
Member
I have a 2004 viper s. Currently it has SLP triple pipes,reed spacers and carbon tech reeds, and opti cool head gasket.
I purchased a peak performance head for it. I am trying to decide what cc domes I should use. Keep in mind this sled has the DCS on it. I only run 91 or better octane ,some time’s with ethenol. I ride between 350’ to 2500’ above sea level. Majority of that time is spent at about 1200’ on trails.
From what I understand the PTO stock has 24cc and center and mag are 21cc. With triple pipes it seems to be the consensus that you can run all three cylinders the same compression.
That being said, should I just get 21cc domes? Or will that be to high across the board being the increase comepresion of the PTO cylinder? The design of the chambers is supposed to reduce the possibility of destination. So maybe I would be ok?
If I go with 22cc domes will I gain or loose anything? This seams to be a happy medium putting things on the safer side.
Will the change in heads require rejeting ?
Also if I do a simple port clean up remove casting flash and maybe polish the exhaust ports while it is apart, will this affect the cc dome I choose?
Love to hear your input or experience on this. Ty.
I purchased a peak performance head for it. I am trying to decide what cc domes I should use. Keep in mind this sled has the DCS on it. I only run 91 or better octane ,some time’s with ethenol. I ride between 350’ to 2500’ above sea level. Majority of that time is spent at about 1200’ on trails.
From what I understand the PTO stock has 24cc and center and mag are 21cc. With triple pipes it seems to be the consensus that you can run all three cylinders the same compression.
That being said, should I just get 21cc domes? Or will that be to high across the board being the increase comepresion of the PTO cylinder? The design of the chambers is supposed to reduce the possibility of destination. So maybe I would be ok?
If I go with 22cc domes will I gain or loose anything? This seams to be a happy medium putting things on the safer side.
Will the change in heads require rejeting ?
Also if I do a simple port clean up remove casting flash and maybe polish the exhaust ports while it is apart, will this affect the cc dome I choose?
Love to hear your input or experience on this. Ty.
I would use 24cc on all 3 with only 91 fuel, DCS and a viper cdi box. A viper has a lot of ign. timing, much more then a srx has. You have triple pipes therefore you don't need more compression. Compression makes heat, heat makes detonation, low octane fuel accelerates detonation and with dcs and 91 fuel you will need to stay conservative on compression.
under my work bench are 12-14 viper cranks, they all have 1 thing in common...... either the center or mag cylinder has a bad/broken rod on them from detonation beating them up, not one with a bad pto cylinder! Which came with less compression, therefore they don't detonate and ruin the engine with the timing and low octane fuels used today.....
under my work bench are 12-14 viper cranks, they all have 1 thing in common...... either the center or mag cylinder has a bad/broken rod on them from detonation beating them up, not one with a bad pto cylinder! Which came with less compression, therefore they don't detonate and ruin the engine with the timing and low octane fuels used today.....
sxviper-s
Member
Thank you for your response Mrviper!
So if I were to use 24cc domes would there be a power loss by doing this? And only advantage being reliableity? And possibly better cooling?
I have been running my current set up for years the way it is problem free, with stock head, no modifications. Running on local premium gas. Should I just leave it as is , like don’t fix it if it’s not broke?
With this head I got two sets of domes. One set is 22cc and one set 23cc. One of the 22cc domes has a very little bit of ruff area just out side the dome. Witch leads me to believe previous owner had some detonation.
What do you think about me running the 23cc domes?
Thank you again for your input!!
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if it works good stock and the dcs doesn't go off with your fuel you run, you wont gain anything of measure going to the other head, don't fix whats not broke......lol
sxviper-s
Member
Bummer. I was hoping to up my power a little while I have the engine apart to replace crank seals. Figured I would do the top end at the same time. It has 7000 problem free miles on it in its current configuration. I just noticed crank seals leaking , so wanted to be pro active and replace be for they fail.
So while it is apart, what would you suggest to add a few more hp to this? All the other stuff is done. Just would like a bit more power while still pump gas and trail friendly.
So while it is apart, what would you suggest to add a few more hp to this? All the other stuff is done. Just would like a bit more power while still pump gas and trail friendly.
NorthernSX
New member
Send MrViper the motor !
That's my suggestion, Im guessing he can add a good 15hp.
I have a redhead going his way soon, then a SRX motor possibly as well.
That's my suggestion, Im guessing he can add a good 15hp.
I have a redhead going his way soon, then a SRX motor possibly as well.
sxviper-s
Member
Recapping what has been said. And maybe I am over thinking this. But am I correct in saying this.
It has been my belief that Yamaha staggered the compression in the viper so they could run the same jetting across all three carburetors.
Is there more to it than that? Possibly to reduce components from creating harmful harmonic vibrations as well?
If all three cylinders have the same compression, is this a possibility? Or would evening out the compression across the three effectively reduce harmful harmonics in the engine?
I guess it is hard for me to rap my head around the idea , that if I currently have stock head pto 24cc center and mag 21cc . That running a head with 2 points higher compression on pto and 1 less point compression on center and mag cylinders would put me any more at risk for detonation.
I could see it on the pto as that would be creating higher compression = more heat.
I thought the combustion chambers on the peak heads were designed to help reduce detonation? Or is it the added surface area on top of the dome that is supposed to aide in the cooling. There for reducing the chance of detonation?
Mr viper. You said most problems you have found have been on both center and mag cylinders. I am assuming this was the case with most stock headed engines?
So effectively reducing my compression on both of those cylinders by one point would effectively reduce possibility of detonation.
Would it make sense to stagger the compression like Yamaha designed it?
It has been my belief that Yamaha staggered the compression in the viper so they could run the same jetting across all three carburetors.
Is there more to it than that? Possibly to reduce components from creating harmful harmonic vibrations as well?
If all three cylinders have the same compression, is this a possibility? Or would evening out the compression across the three effectively reduce harmful harmonics in the engine?
I guess it is hard for me to rap my head around the idea , that if I currently have stock head pto 24cc center and mag 21cc . That running a head with 2 points higher compression on pto and 1 less point compression on center and mag cylinders would put me any more at risk for detonation.
I could see it on the pto as that would be creating higher compression = more heat.
I thought the combustion chambers on the peak heads were designed to help reduce detonation? Or is it the added surface area on top of the dome that is supposed to aide in the cooling. There for reducing the chance of detonation?
Mr viper. You said most problems you have found have been on both center and mag cylinders. I am assuming this was the case with most stock headed engines?
So effectively reducing my compression on both of those cylinders by one point would effectively reduce possibility of detonation.
Would it make sense to stagger the compression like Yamaha designed it?
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observations from your information:
1.) your using low octane fuel, 91 is LOW octane fuel for a "performance application" where there is high load on the engine(triple pipes,higher rpm, etc.)
2.) vipers have very high ignition timing, more ignition timing puts more heat into the piston, retarded timing puts more heat into the pipe.
3.) you have added triple pipes which run at a higher operating rpm(more load), this gives more power, along with more hp comes heat, heat is the by product of more hp(more heat in coolant,raises operating temp of coolant/engine, hence the need for rear cooler in a viper)
4.) a viper has increased compression over a srx on the mag and center cylinders of the engine, the pto is larger and less compression. Yamaha merely did this because they thought the simplistic non staggering of main jets was a big deal to consumers. Its been found thru many years of these sleds research and development that the center and mag cylinders are the 2 cylinders that consistantly blow up from low octane fuel, higher compression and increased ignition timing.
5.) when bender racing came out with their opti cool headgasket for use with their pipes, theres a reason its thicker then stock.... it reduces compression, which is a reduction in heat because they too found out that increased compression in a viper, adding triple pipes, and low octane fuel is a sure mix for detonation!
6.) you have a 2004 viper with dcs, these are sensitive to fuel quality and mods to the engine will result in the dcs going off and retarding the time, possibly going into limp mode. these engines can still burn down even with this feature. I can clutch a bone stock 2002 srx also equipped with dcs and triple pipes into making the dcs go off for nothing more then applied load to the engine....the fix...... use higher octane fuel!
I merely gave you information and opinion on what you asked for, you don't have to follow my information or reccomendations, its your sled. Just be known youll find the cost of pistons,crankshafts,cases to be quite expensive anymore and rapidly declining in availability. You can change 1cc here or there and more then likely you will not be able to tell the difference in power 1 bit, your not changing the compression by 1 point but changing the volume of the chamber by 1cc. Its not gonna be worth anything of great measure of power increase. Anything under 5hp and you cant tell a difference in riding the sled other then that your wallet is thinner.
just for FYI- When I trail port a viper engine I do not do any head work to it, by porting it, when it goes back together the compression will go down because the exhaust port is larger, this is a good thing with a viper. It aids in reliability. The aftermarket head could very well have more surface contact with the water on the domes but it wont stop detonation entirely, detonation comes from the heat in the piston top and the cylinder. If it cooled a few more degrees it could delay it slightly if the rest of cooling system over achieved but it cant stop it.
If you have ridden that sled with the pipes,jetting and 91 octane for this long with no dcs lights, and or problems don't fix what isn't broke as most guys have not been as lucky as you. Look into getting some work done on the cylinders, lightweight wristpins, mod the reed blocks, dial in the clutching to perfect, reduce parasitic drag in the rear skid with oversize idler wheels, slippery hy fax,etc. and it will be of more benefit then just the head by far!
1.) your using low octane fuel, 91 is LOW octane fuel for a "performance application" where there is high load on the engine(triple pipes,higher rpm, etc.)
2.) vipers have very high ignition timing, more ignition timing puts more heat into the piston, retarded timing puts more heat into the pipe.
3.) you have added triple pipes which run at a higher operating rpm(more load), this gives more power, along with more hp comes heat, heat is the by product of more hp(more heat in coolant,raises operating temp of coolant/engine, hence the need for rear cooler in a viper)
4.) a viper has increased compression over a srx on the mag and center cylinders of the engine, the pto is larger and less compression. Yamaha merely did this because they thought the simplistic non staggering of main jets was a big deal to consumers. Its been found thru many years of these sleds research and development that the center and mag cylinders are the 2 cylinders that consistantly blow up from low octane fuel, higher compression and increased ignition timing.
5.) when bender racing came out with their opti cool headgasket for use with their pipes, theres a reason its thicker then stock.... it reduces compression, which is a reduction in heat because they too found out that increased compression in a viper, adding triple pipes, and low octane fuel is a sure mix for detonation!
6.) you have a 2004 viper with dcs, these are sensitive to fuel quality and mods to the engine will result in the dcs going off and retarding the time, possibly going into limp mode. these engines can still burn down even with this feature. I can clutch a bone stock 2002 srx also equipped with dcs and triple pipes into making the dcs go off for nothing more then applied load to the engine....the fix...... use higher octane fuel!
I merely gave you information and opinion on what you asked for, you don't have to follow my information or reccomendations, its your sled. Just be known youll find the cost of pistons,crankshafts,cases to be quite expensive anymore and rapidly declining in availability. You can change 1cc here or there and more then likely you will not be able to tell the difference in power 1 bit, your not changing the compression by 1 point but changing the volume of the chamber by 1cc. Its not gonna be worth anything of great measure of power increase. Anything under 5hp and you cant tell a difference in riding the sled other then that your wallet is thinner.
just for FYI- When I trail port a viper engine I do not do any head work to it, by porting it, when it goes back together the compression will go down because the exhaust port is larger, this is a good thing with a viper. It aids in reliability. The aftermarket head could very well have more surface contact with the water on the domes but it wont stop detonation entirely, detonation comes from the heat in the piston top and the cylinder. If it cooled a few more degrees it could delay it slightly if the rest of cooling system over achieved but it cant stop it.
If you have ridden that sled with the pipes,jetting and 91 octane for this long with no dcs lights, and or problems don't fix what isn't broke as most guys have not been as lucky as you. Look into getting some work done on the cylinders, lightweight wristpins, mod the reed blocks, dial in the clutching to perfect, reduce parasitic drag in the rear skid with oversize idler wheels, slippery hy fax,etc. and it will be of more benefit then just the head by far!
Mac
Member
I rarely see discussions about the benefits or solutions of engine cooling other than rear cooler. The Viper couldn't cool itself from day one at 120 HP. Once modified to 160 or 170 HP the engine suffers from heat exhaustion. Many tuners solve the problem by drowning the engine with fuel which does alleviate the problem to some degree but reduces HP that we are trying to increase. Lower coolant temps prevents detonation and your engine life will improve if you can figure out how to lower operating temperatures. Mr Viper touched on this by saying adding a rear heat ex-changer. Although this does help it does not solve all issues and did little to help my BB. Ive squeaked more pistons than I care to admit and boiled the coolant out of several engines. I never knew how bad the problem was until i installed an inline digital temp gauge right where the coolant exits the head. I run a BB that always ran hot and over 170-180 or more. Our all aluminum engines cannot operate for long at these temps for very long. I finally installed a go cart radiator that drops my temps down to 145-150 degrees maximum. Problem solved and i can lean out the mixture for Max HP and fun factor.
There has to be a better solution than scabbing in a go cart radiator as I did. Lets here it.
---mac---
There has to be a better solution than scabbing in a go cart radiator as I did. Lets here it.
---mac---
sxviper-s
Member
Thank you once again Mrviper for your input! This is in line with the type of information I am looking for/ interested in.
The reason for my interest in this is because I am looking for a bit more power. And when I decide to move forward, I want to know how,why and what work is being done. Also that it is done by someone qualified. I have had my good and bad experiences with engine and chassis builders over the years drag racing. I know the importance of a qualified technician.
I have exhausted most all other options on this sled without turning back to the engine for more performance.
Clutching has been done , primary heal clicker and secondary Hauck roller , and helix. This was all set up with the help of an old racer and mechanic from Pineer motor sports. Retired now, as was my suspension years ago by Bruce from Pineer motor sports. Srx rear heat exchanger,graphite hifax, track USA 136 extension with new 11/4” ripsaw track, 108 megabite picks down the center 1.325” double backers , 4th wheel kit, over sized wheels, 2 extra wheel kits, gearing, 8 tooth drivers,CB drop brackets,transfer rod nuts, boss seat to reduce weight, Ohlins all the way around. And a few more items I am sure I am forgetting.
I have ported the reed blocks, reed spacers are in, new carbon tech reeds, SLP pipes, and I added the opti cool head gasket this year. But had no problems previously with heat. It was more preventative on my part.
Thank you by the way, I was not aware the opti cool head gasket is actually thicker than stock.
I ask questions to learn more than I currently know. I know enough to get in trouble. Lol. And trouble is where I am headed.
So with all this information I believe this is what my plans are. Keep in mind I am a racer, nothing is ever fast enough.
1 have a qualified person port jugs for trail riding,
2 add peak performance head with 23cc domes and run the opti cool gasket.
3 add a light weight brake rotor.
4 not sure about this. But thinking of heat wrapping my pipes. What are your thoughts on this?
5 take to dyno after complete to tune it all in.
At this time new Yamaha pistons rings will be installed as well as bearings and seals.
Mrviper you had mentioned lightweight wrist pins. Who carries them? Where may I purchase them?
Mr viper. I would like to kindly thank you for your input and thoughts on this. It is obvious to me that you truly care and are passionate about what you do.
Ok blast me now. Lol
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NorthernSX
New member
Wiseco makes the wristpins
sxviper-s
Member
No one gets to the front following some one else. Eventually they have to , do change / something to pass that person. Knowledge is power.
sxviper-s
Member
sxviper-s
Member
found this on eBay. 5.5” long looks like I could add three in total. One in radiator hose under clutch’s and two more to rear heat exchanger under tube covers outside tunnel extension. May help with cooling.There are lots of rear cooler options a person could install that are larger than the stock one. Many big bore machines in my area are running large rear u-coolers.
i wouldn't waste the time money or effort. you will be "radiating heat directly into your clutches. Plus more weight and more hose clamps.
if you can't add power take away weight! simplify as much as possible! As far as cooling, have you considered evans waterless coolant? Im running a rear cooler from a 2007 m7 and have considered running a warmer thermostat.. granted this is in powder.
Attachments
sxviper-s
Member
I have discussed different options with restricting coolent flow to front heat exchanger, opening cooling flow around thermostat to utilize more of the cooling system. Prior to thermostat opening.
Adding larger heat exchanger. Which effectively these would become. This would not add any more clamps in the rear then I currently have. Also I can not see these weighing any more than half lb each. If that. I could loose a pound or two anyway. Lol. So two in the rear should only help. As for the front. The amount of heat coming off this should not affect the clutches at all. Also this would be at the tail of the loop, meaning cooler temp by the time coolent gets there. The movement of air around the clutch should send it right out by the vent by your knee.
Engine and exhaust temperatures I believe would have a far greater Affect on clutches. Also correct clutch settings.
My self personally, I have not had a problem with overheating. I look at this as preventative, no different than adding the SRX rear heat exchanger. But more power does create more heat.
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sxviper-s
Member
Compression ratio is CC of one cyl + CC of one head as measured with the piston at TDC, divided by the CC of the head. If you use a flat plate to CC the head the volume will be wrong (for this calculation) as it does not take into account the crown of the piston.
If you have a 90 cc motor and the head is 10 cc, your compression ratio is 10.0:1. 90+10=100, 100/10=10.0:1 ratio.
Is this calculation some what accurate?
Based off this if I am correct ,
700cc /3=233.33333333 + head cc of 21cc for example = 254.33333333/21= 12.1111111111 or 12.1 compression?
So a break down.
25cc head. = 10.3333
24cc head. = 10.72222
23cc head. = 11.1449275
22cc head. = 11.6060
21cc head. = 12.11111111
20cc head. = 12.666666666
I know this is ruff, but is it close?
Knowing the opti cool head gasket is thicker. We know it will drop compression as well.
Anyone happen to know the difference in thickness? And what it = in cc??
Guessing at 1cc difference for the opti cool head gasket. Would this approximately put stock viper compression at.
Say 25cc PTO = to approximately 10.333333
And center and mag at approximately 11.6060?
Anyone have more insight on this??
If you have a 90 cc motor and the head is 10 cc, your compression ratio is 10.0:1. 90+10=100, 100/10=10.0:1 ratio.
Is this calculation some what accurate?
Based off this if I am correct ,
700cc /3=233.33333333 + head cc of 21cc for example = 254.33333333/21= 12.1111111111 or 12.1 compression?
So a break down.
25cc head. = 10.3333
24cc head. = 10.72222
23cc head. = 11.1449275
22cc head. = 11.6060
21cc head. = 12.11111111
20cc head. = 12.666666666
I know this is ruff, but is it close?
Knowing the opti cool head gasket is thicker. We know it will drop compression as well.
Anyone happen to know the difference in thickness? And what it = in cc??
Guessing at 1cc difference for the opti cool head gasket. Would this approximately put stock viper compression at.
Say 25cc PTO = to approximately 10.333333
And center and mag at approximately 11.6060?
Anyone have more insight on this??
Mac
Member
If I may ask. What will you do with the info once calculated?
http://www.torqsoft.net/compression-ratio.html
http://www.torqsoft.net/compression-ratio.html
sxviper-s
Member
It is more for comparison than anything else. From stock to current with opti cool head gasket. And also trying to determine what I can get away with. Just trying to figure what is and would be comparable to what I have now.
Taking what I have currently. Stock head with opti cool head gasket. Assuming the gasket provides approximately 1cc more to chamber volume than stock gasket. It would be comparable to a 22cc chamber on center and mag. And 25cc on pto. Taking this into consideration, I have not had any problems with detonation here. I am wondering if it is safe to assume that if I go with aftermarket head with 21cc domes across the three cylinders and use the opti cool head gasket. Being it is thicker than stock, it effectively lowers the compression. Would it then be comparable to a 22cc head dome? Similar to adding a cc of volume. Would I be safe here? Still running the 91+ octane fuel.
Also taking into account that this will be ported. And from what I understand porting allows a little smaller chamber as well? Just learning. I always question everything.
Forgive me for my ignorance, but do you happen to know the stroke of our engines? .62?
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