what kinda gains am i looking at? Mr.viper700?

redsnake3

redsnake3

New member
Joined
Feb 3, 2005
Messages
1,171
Age
41
Location
labrador home of snow
i just got a set of hauck's heads with interchangeable domes and the heads are gonna have about 200psi at sea level where i am too. what kinda fuel should i run? this is gonna only be every other weekend for racing. im thinking im gonna need some c16 or i might be able to run some 110. anyway what kinda power increases am i looking at? where is the power gonna be noticeable? and will the pistons hold up under that kinda load? i was thinking of having the squish angle raised to add some volume to take away some compression and run a little hotter. i would love too hear everyones opinions on this, but only if you know what you are talkin about.

Thanks
 
I believe you need RIGHT squish height because right height will cool down the piston. too much or too little won't be good.
200Psi sound pretty high for me, but mr. viper knows for sure.
 
so your asking me what kind of gains your gonna get from raising the compression ratio only in the engine? there isnt anyone that can answer that, it would all depend on your porting specs, the carbs, pipes, timing. Youd have to put it on a dyno to measure that!
One thing that compression will add for sure is heat! a engine with high compression makes heat faster! sure... it adds power, but theres other things that need to be done as well. You wont do anything to the stock pistons with 200lbs of compression, they are powder forged units and will take that with out even thinking about it.

Squish angle and clearance are something that needs to be set up for the motor to work properly, this all depends on what your going to do with the sled and for how far of a distance and exactly what fuel you will use on a continous basis?????
 
well the sled is only gonna be ran with 200 psi at the races which are 660ft. so at one time the sled will run a max of 10seconds at wot, has stock timing, carbs and am running cpr pipes with sportport(racelogic) porting. i would like to know what kind of fuel i will need to run. what kind of squish angle should i run since i am gonna add some volume to the domes anyways and was gonna change the squish angle. would you be able to do that? send me a pm with a price if possible.

thanks
 
Its not just as simple as swap the domes and go trail ride, ALL of the carburation settings will be differnt, clutching will be differnt, porting will sometimes need to be changed, because your changing the amount of power output of the engine by changing the cmpression ratio, its not a simple cut and dry swap.

squish clearance affects the turbulance in the head as well as does the squish angle and relief section. What kind of squish are you running with your current engine set up? usually around .052"-.050" is good all around clearance, race applications will be tighter! I think you may be better off somewhere in the middle of all this and be able to run pump fuel since it sounds like a dual purpose sled. The power gain you get may not be all worth the amount of time invested to dial it all in and back to the trail settings everytime your done racing.

An engine will make more power with less octane fuel, for example 87 octane versus 100 octane, the 87 will produce more power because the octane is the fuels ability NOT to burn, the reason the race fuel is such high octane is simply it resist the tendency to detonate, this comes from high compression, advanced ign timing, this all increases the ability of the engine to have detonation, from the increased heat of higher compression,timing etc.

Its all about getting the parts in the engine and your added pipes and such to work together.
 
the sled is basically just a race sled, i dont ride it very often anymore and wouldnt mind swapping the heads to trail ride. i would keep all the clutching and carbs the same just for the convenience if it will help me with racing. i have access to many sleds to trail ride so it wouldnt be a problem. i did know that you will make more power using a lower octane fuel but will like it to not blow a piston all the time. i dont have the head on the sled yet it is supposed to be here tomorrow or the next day then i will check the squish. i thought the squish should be between .o55 - .060 to be safe so i was runnin about .065 before.
any suggestions? are you willing to cut down these domes for me when i get all the measurements you need? send me a pm with a price.

thanks very much, i know how busy you must be with the upcoming season and appreciate all your patience. you are really good at explaining all the technical points, most people who know what they are doing cant explain how it works they just know that it does.
 
when ya get it on do some squish checks and let me know, and what size the domes are and we can go from there to get it set up.
 
well i got the final #'s and im not impressed. i was told his sled was running 165psi at about 8000ft. and i should expect 180-200psi. well did a cold check today and with 3 layers of head gasket im looking at 0.090" squish and 125psi. with just 1 layer i got 0.069" and 145psi. im not happy. i was looking to get 175-180psi. the squish band is much wider on these domes also. let me know what you think Mr.viper. as i am not happy with this. or should i be? i dont know maybe its just my crushed expectations.
 
Redsnake,
Do you know what exactly was done to the other guys sled? was it ported and or stroked? Usually you lose a few pounds of psi of compression due to porting. If the other sled was truely making 165 psi at 8000 ft then you should be making about 190-200 psi @ sea level. What size domes were these again? Why exactly was the other person selling?(ask yourself- Don't answer to me) hmmm, you have a dilemma on your hands.
 
my sled has really mild trail porting. i lost about 5psi on the cpr head. his sled was not stroked or ported. when i talked to him he said his was at 165psi so he guessed it would be at about 200 psi. so i was happy. these are 19cc domes and everything is exactly like he said its just that the compression isnt adding up. :dunno:

oh and i just finished a leak down test and had aobut 6-7% on all cylinders.
 
I have 20 cc domes on my sled, and I know for sure that I've got 160 psi compression with a stock 3 layer gasket. Something doesn't sound right, over there.19cc domes and 233 cc of cylinder volume = about 12.25:1 compresson ratio. Are the domes marked/labeled in any way as to be able to determine the chamber size? Do the domes positively seat in the pockets, are they solid and flush with the mating surface so that they aren't moving or recessed a tiny bit biving you a bad compresson check?
 
the domes say 19cc on them. i think they are seating right.im gonna haul them off again tonight and see if there is anything out of the ordinary with them.
 
I have a couple questions, do you only have 1 base gasket in this engine? because .090" squish is awfull big.

whats the deck clearance? the distance piston edge is from top of cylinder edge when at TDC? stock is .012-.014"

a stock viper has 24cc chamber on the PTO, and 21cc on the mag/center cylinder so 19cc is no where ever gonna be 200lbs of compression.
Your reading of 165lbs sounds right for the dome size if you only have 1 base gasket in.
The differance will come in with the squish clearance, its a mile too wide, you need to be down to .052-.050" this will yield alot higher compression from those same 19cc if this was the spec it was set up with, looks to me like you need to deck the whole head and domes to get down to where you need to be with 1 layer of gasket. I would deck the works about .017-.019", youll be in the right squish clearance area and your compression will jump way,way up.

nothin wrong with a wide band, ya just need em set up.
 
Last edited:
i only have 1 base gasket and 1 layer in the head gasket and im only getting 145psi on the hauck head. with my cpr head i will have around 130-135 psi. this is a cold reading. i will get the deck clearance in a couple hours and post it. tell me how much you want to cut these domes. i want around 175-180 psi or whatever you would suggest, i can use the other head for riding or get another set of domes.

Let me know how much cause i want this done.
 
You must log in or register to reply here.


Back
Top