Turbo cam selection





#1
My bike is using a GT4094 turbo. I know my bike would benefit from some turbo cams allowing it to move some of the air that this large turbo is pushing. I only street ride and I enjoy how my turbo acts on the street now, just wondering what you guys think of in terms of which cams and if there are different grinds for different styles of performance
 
#4
Ace the problem with cams that will flow more air for your big turbo is you will give up a little bottom end. I'm sure there is some lag with your setup now so this may add to it a little.
 
#5
Keep cam changes real conservative, turbo makes small cams act like bigger ones, (only the negative effects ) look at turbo specific cams or cams advertised to increase hp right across the range, may have to play with cam timing a bit to get the best results, and be prepared to take them out and go back to stock if the combination of low compression and big turbo with bigger cams puts your hp down instead of up
 
#6
Ace the problem with cams that will flow more air for your big turbo is you will give up a little bottom end. I'm sure there is some lag with your setup now so this may add to it a little.
good info...im not well educated on all the dimensions and aspects of how camshafts can change your power. Motorhead mentioned this when my bike was being built and I was just coming around to thinking of it now....but it would be alot of work and probably $1K+.....i'm happy with what i have now this was just something that crossed my mind over the weekend. I was thinking of selling my bike last couple of weeks because i have moved and haven't had a chance to ride. After i moved the bike this weekend i found myself just staring at it and thinking "NO WAY NO FUKN WAY" hahaha
 

ogre

Call me Liberace!
Registered
#7
Ace the problem with cams that will flow more air for your big turbo is you will give up a little bottom end. I'm sure there is some lag with your setup now so this may add to it a little.
ok, a little cam and turbo knowledge is needed here. to the OP, if you want better boost response, better midrange and better topend, here's what you do... step one, pull the head off the bike and get it ported. i'd normally recommend porting it yourself, but with questions like the one you are asking leads me to believe that may end badly. so, in short, step one is ported head. velocity (for low end torque) is moot, due to the fact that your motor is boosted, if you want low end torque, you need to impact your boost response, ie, how soon/fast/hard your turbo spools. one way would be to get a smaller exhaust side, preferably in conjunction with an anti-surge housing. another way is a ported/polished head, as mentioned above (in conjunction with the turbo, stop thinking n/a boys). the third way is what's called a split duration cam setup. basically, your intake cam has more lift and duration than the exhaust cam. imagine the motor sucking in air (or swallowing, again, turbo not n/a) through a garden hose, then blowing out through a straw. the air going through the straw will be going much faster, imparting more velocity to the turbine, giving you faster spool. another effect from higher exhaust velocity is that more heat is transferred to the turbine. the exhaust gasses will be expanding more violently if they hit the turbine sooner, and will again, spool faster.


so, in closing, ported head, split duration cams, smaller exhaust housing on the turbo, and an antisurge housing on the turbo.

god i love turbos:bowdown:
 
#8
ok, a little cam and turbo knowledge is needed here. to the OP, if you want better boost response, better midrange and better topend, here's what you do... step one, pull the head off the bike and get it ported. i'd normally recommend porting it yourself, but with questions like the one you are asking leads me to believe that may end badly. so, in short, step one is ported head. velocity (for low end torque) is moot, due to the fact that your motor is boosted, if you want low end torque, you need to impact your boost response, ie, how soon/fast/hard your turbo spools. one way would be to get a smaller exhaust side, preferably in conjunction with an anti-surge housing. another way is a ported/polished head, as mentioned above (in conjunction with the turbo, stop thinking n/a boys). the third way is what's called a split duration cam setup. basically, your intake cam has more lift and duration than the exhaust cam. imagine the motor sucking in air (or swallowing, again, turbo not n/a) through a garden hose, then blowing out through a straw. the air going through the straw will be going much faster, imparting more velocity to the turbine, giving you faster spool. another effect from higher exhaust velocity is that more heat is transferred to the turbine. the exhaust gasses will be expanding more violently if they hit the turbine sooner, and will again, spool faster.


so, in closing, ported head, split duration cams, smaller exhaust housing on the turbo, and an antisurge housing on the turbo.

god i love turbos:bowdown:
I wouldn't come within thinking of porting my head myself....I did consider having it done By Jerry Cooper or Rick Ward but decided not to since Richard from RCC said the gains would only be seen at High RPM....and with as much power as I have the ability to put down now there really is no point. On the other hand WEB 445/415 i believe is what has been recommended to me by Dennis "motorhead" those are the cams he used to break 700HP with this kit...but for right now i just need to get my boost issue resolved and then down the road might consider doing some cams
 

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