hey guys i was wondering at what boost pressure should i change my compression ratio, and by changing the gasket will that work and which one to use. just changed the pistons to cp-e stage 2, and rods to the k1 rods. was considering this as i wish at a later stage to change to a gtx3076.
compression ratio
- Thread starter saint340
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- Banned For Being A Troll
Changing the compression ratio is normally only if you plan to run the sort of boost that can actually cause detonation.
Detonation can occur by using too low of octaine, too high of compression, too lean a mixture, to aggressive timing, too hot intake, too hot a spark plug. Several factors should be looked at in total.
What is your HP goal...
What boost level do you have to get the turbo to reach that goal...
Is that boost level bringing you too close to the limit.
What Gas you plan to run.
how aggressive the timing curve you are running
can you adjust the timing with management or is it preset
do you have active KR, or will the timing remain unchanged during detonation.
From Experience, there is a balance between Timing and HP
I can make as much HP at
10 PSI 8:1 93 with aggressive timing as
15 PSI 9:1 93 with reduced timing...
I cant run the same timing in the higher compression motor because it will detonate sooner and fail. I need to relax the timing on the 9:1 engine to maintain the same risk of detonation..
The overall goal with lowering the compression is to be able to safely make the highly boosted engine also have timing aggressive. You maintain a certain safety margin if you are able to run lower compression.
The Cost of reducing the compression ratio is loss of lower end torque (Usually also off boost), which on a large turbo car is harder to get.
Solution, is to Downshift.
A non mechanical way to run high compression at high boost is Meth Injection. AEM has a great video on how it works. I do not suggest it to you at this point, you are still planning the build out and that sort of modification should only be used at the end to keep a car together...
Detonation can occur by using too low of octaine, too high of compression, too lean a mixture, to aggressive timing, too hot intake, too hot a spark plug. Several factors should be looked at in total.
What is your HP goal...
What boost level do you have to get the turbo to reach that goal...
Is that boost level bringing you too close to the limit.
What Gas you plan to run.
how aggressive the timing curve you are running
can you adjust the timing with management or is it preset
do you have active KR, or will the timing remain unchanged during detonation.
From Experience, there is a balance between Timing and HP
I can make as much HP at
10 PSI 8:1 93 with aggressive timing as
15 PSI 9:1 93 with reduced timing...
I cant run the same timing in the higher compression motor because it will detonate sooner and fail. I need to relax the timing on the 9:1 engine to maintain the same risk of detonation..
The overall goal with lowering the compression is to be able to safely make the highly boosted engine also have timing aggressive. You maintain a certain safety margin if you are able to run lower compression.
The Cost of reducing the compression ratio is loss of lower end torque (Usually also off boost), which on a large turbo car is harder to get.
Solution, is to Downshift.
A non mechanical way to run high compression at high boost is Meth Injection. AEM has a great video on how it works. I do not suggest it to you at this point, you are still planning the build out and that sort of modification should only be used at the end to keep a car together...
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thanks bud looking at making as much power as i can, am planning on using a 50/50 water meth injection in the not to distant future. will be running 95 octane with octane booster. currently got a fmic, with sri, cp-e hpfp, soon catless downpipe with exhaust. just wanna make sure the build is done properly.
am scared of blowing the motor, that is why was asking about compression ratio. with the stock turbo, will run 16-18 psi, and when i can later a gtx3076r, thats when i am worried about the boost.
am scared of blowing the motor, that is why was asking about compression ratio. with the stock turbo, will run 16-18 psi, and when i can later a gtx3076r, thats when i am worried about the boost.
- :
- Banned For Being A Troll
To explain more,
The Compression Ratio, like everything else is a balance, a trade off. Giving up one thing for another..
Just like a Turbo
Too Big and it will never spool, but it will be efficient..
Too Small, and it will spool very well, but might prevent meeting a HP goal.
Setting the Comp Ratio Too low and you will loose low end, but be able to boost crazy. Setting it too close to stock could limit how much boost you can go past what the designers planned for it.
I went from 9.1:1 to 8.5:1, such a small change lets me run silly boost and a timing curve that "On Paper" should grenade the engine all over...
BTW: Thanks for looking into my car, I don't know if you clicked the link at the bottom, but if you like more information on it there is a build thread as well..
http://www.mazdas247.com/forum/showthread.php?123804006-Mp5t&highlight=
1/4 Of my family is from Durban. I plan to visit them in the next 5 years...
The Compression Ratio, like everything else is a balance, a trade off. Giving up one thing for another..
Just like a Turbo
Too Big and it will never spool, but it will be efficient..
Too Small, and it will spool very well, but might prevent meeting a HP goal.
Setting the Comp Ratio Too low and you will loose low end, but be able to boost crazy. Setting it too close to stock could limit how much boost you can go past what the designers planned for it.
I went from 9.1:1 to 8.5:1, such a small change lets me run silly boost and a timing curve that "On Paper" should grenade the engine all over...
BTW: Thanks for looking into my car, I don't know if you clicked the link at the bottom, but if you like more information on it there is a build thread as well..
http://www.mazdas247.com/forum/showthread.php?123804006-Mp5t&highlight=
1/4 Of my family is from Durban. I plan to visit them in the next 5 years...
- :
- Banned For Being A Troll
I believe that using a Head gasket to reduce the Compression is dangerous.
Changing the pistons is the better way.
Thanks much.
Changing the pistons is the better way.
Thanks much.