Login    Forum    Search    FAQ

Board index » Racing Forum » Engine & Cylinder Head Tech




Post new topic Reply to topic  [ 9 posts ] 
Author Message
 Post subject: heads for blown motor
 Post Posted: Fri Apr 21, 2006 9:10 am 
Offline
User avatar

Joined: Wed Apr 19, 2006 4:25 pm
Posts: 422
Location: Beaverton Ontario Canada
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


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Apr 21, 2006 9:39 am 
Offline
Moderator
User avatar

Joined: Tue Apr 18, 2006 3:20 pm
Posts: 1457
Location: Missouri
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


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Apr 21, 2006 12:04 pm 
 
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


Top 
  
 
 Post subject:
 Post Posted: Fri Apr 21, 2006 8:25 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 11:04 pm
Posts: 402
Location: Virginia Beach, VA
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

_________________
Race Flow Development
Simultaneous 5-axis CNC Porting
Image


Top 
 Profile  
 
 Post subject:
 Post Posted: Wed Apr 26, 2006 3:32 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:39 pm
Posts: 239
Location: Kalamazoo MI
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

_________________
James
79 Z28 496 BBC....
Image


Top 
 Profile  
 
 Post subject:
 Post Posted: Wed Apr 26, 2006 4:39 pm 
Offline
Moderator
User avatar

Joined: Tue Apr 18, 2006 3:20 pm
Posts: 1457
Location: Missouri
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


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Apr 28, 2006 4:26 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:39 pm
Posts: 239
Location: Kalamazoo MI
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

_________________
James
79 Z28 496 BBC....
Image


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Apr 28, 2006 5:47 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:54 pm
Posts: 1619
Location: Western Illinois
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.

_________________
Older I get the less I know for sure Dennis


Top 
 Profile  
 
 Post subject:
 Post Posted: Sun May 14, 2006 6:24 am 
Offline
User avatar

Joined: Wed Apr 19, 2006 4:25 pm
Posts: 422
Location: Beaverton Ontario Canada
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


Top 
 Profile  
 
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 9 posts ] 

Board index » Racing Forum » Engine & Cylinder Head Tech


Who is online

Users browsing this forum: No registered users and 3 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: