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heads for blown motor
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Author:  henny496 [ Fri Apr 21, 2006 9:10 am ]
Post subject:  heads for blown motor

Hello
How important is the port/head work on a blown motor as compared to a NA engine?
Other than port size, is there a big difference on a head for a blown motor?
I know I have not asked too much and this is a very general question, but I would like to hear some info, before I can get more specific in my question
I will be doing a blown street/strip motor. I have some heads, but I am not so sure on how much time I should spend on them....
thanks
Tom

Author:  rick360 [ Fri Apr 21, 2006 9:39 am ]
Post subject: 

I think the intake should be ported very similar to a N/A engine. You still want the air to move into the cylinder freely. That will create less backpressure on the blower and will move more air/fuel into the cylinder with less boost which will reduce both the heat generated and parasitic drag from the blower.

The exhaust side should be bigger overall than N/A to get the larger amount of exhaust out of the engine. Exhaust size is related to HP. When you increase the HP, you need to increase the exhaust.

Rick

Author:  Anonymous [ Fri Apr 21, 2006 12:04 pm ]
Post subject: 

not trying to steal thread just thought while ? was asked i might jump in to sorry if i messed you up
good info i was wondering the same thing b/c im getting ready to build my blower motor and i was looking at dart iron eagle heads do you think theylle work good looking at the 230cc

Author:  CBoggs [ Fri Apr 21, 2006 8:25 pm ]
Post subject: 

Rick360 wrote:
I think the intake should be ported very similar to a N/A engine. You still want the air to move into the cylinder freely. That will create less backpressure on the blower and will move more air/fuel into the cylinder with less boost which will reduce both the heat generated and parasitic drag from the blower.

The exhaust side should be bigger overall than N/A to get the larger amount of exhaust out of the engine. Exhaust size is related to HP. When you increase the HP, you need to increase the exhaust.

Rick


Yea, .. what he said, .. \:D/

Curtis

Author:  radicalz [ Wed Apr 26, 2006 3:32 pm ]
Post subject: 

CBoggs wrote:
Rick360 wrote:
I think the intake should be ported very similar to a N/A engine. You still want the air to move into the cylinder freely. That will create less backpressure on the blower and will move more air/fuel into the cylinder with less boost which will reduce both the heat generated and parasitic drag from the blower.

The exhaust side should be bigger overall than N/A to get the larger amount of exhaust out of the engine. Exhaust size is related to HP. When you increase the HP, you need to increase the exhaust.

Rick


Yea, .. what he said, .. \:D/

Curtis



Rick and Curtis does that involve increasing the physical valve size or can HP be obtained by increasing the port volume and effieciency by porting.... :-k :-k

Author:  rick360 [ Wed Apr 26, 2006 4:39 pm ]
Post subject: 

radicalz wrote:
Rick and Curtis does that involve increasing the physical valve size or can HP be obtained by increasing the port volume and effieciency by porting.... :-k :-k


If you are referring to the exhaust side of the head, then yes it could normally use a bigger valve as well as a bigger port and header. The amount depends on how much boost (ie: HP) you are putting to it, which will deterimine how much exhaust has to get out.

Rick

Author:  radicalz [ Fri Apr 28, 2006 4:26 pm ]
Post subject: 

Rick360 wrote:
radicalz wrote:
Rick and Curtis does that involve increasing the physical valve size or can HP be obtained by increasing the port volume and effieciency by porting.... :-k :-k


If you are referring to the exhaust side of the head, then yes it could normally use a bigger valve as well as a bigger port and header. The amount depends on how much boost (ie: HP) you are putting to it, which will deterimine how much exhaust has to get out.

Rick


....see learning something new everyday..... :-k :-k :-k....Now on a blower motor would it also help to in addition to the exhaust port work and valve size increase....to also have a big tube primary on the header to improve flow out??? :-k :-k

Author:  Bubstr [ Fri Apr 28, 2006 5:47 pm ]
Post subject: 

Old school here but was always taught, the basics of a blown motor is big comeing in, big going out , you can't hardly get too much fuel to them and colectors are for NA engines, the blower makes it's own flow. Just give it room to do it. And too much overlap on cam will give you very hot soomies.

Author:  henny496 [ Sun May 14, 2006 6:24 am ]
Post subject: 

Hello
How far can you go with 077 heads on a blower motor that will see street use?
What I mean is, are they going to be too much of a hinderance. If the cubes are say around 500, and being a street/strip car, will good ported 077 heads be enough?
Perhaps, I should ask how much can you get out of them?( more than a street/strip car can handle?????) This is not a 30,000 mile a year car, but not 3 -5 miles a week car either
I am probably asking too general a question here, but hopefully I can get some input, so I can narrow down my question
take care
Tom

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