Drivetrain Advice on new head
4th Gear
Joined: Aug 2002
Posts: 510
Likes: 0
From: Orange Park, Fl.
Heads.. vs valve size??
Increasing the flow thru valve size has been around forever.. then porting added to that , and now the C&C is the future... But it is ALL in the application of the engine the head is going on... 20-32 BHP isnt the HP at the wheels, is it!! Unless there is an engine dyno... out of the car type.. BHP is a guess at best!! How much DT loss has been beat up over the years... 14% ...10%...20 %.... blah.. blah...ect!!
Even the SAE corrections are not the best way to do it... if you are in FL. and pull a 25 WHP in 95 degrees, then you KNOW it will be better in a cool 70 degrees and high humidity.. yes?? We quit with the SAE HP or the BHP guess... when we do a mod.. we state the actual WHEEL to the ground HP!!
With STOCK valve size and port work, the engine is still a good drive in traffic .. without boost!! Add a larger valve .. and it slows the velocity into the chambers and the loss in traffic is a given.. just read all the past posts... OR look at their dyno sheets!! If it is a track car.. then all we try to do is out the window... they are never below the power curve in the 4000-4500 rpm range... who needs trafic lite performance.... they need all the top end they can get!! Huge valve and huge ports!!
We are now going to a .5 mm over size. valve.. the loss of the low to mid range is corrected with the correct port and valve work ( under the valve) WE feel that more than a stock valve size or a +.5 mm size is good to talk about.. but the dailey comute to work, or the traffic lite under the boost level sux!! Actually the stock heads are a great head... the valve size is good ( two of them remember..??) As for the bottleneck on the MINI.. dont think so.. yes there is more power in head work, but the stock head is great!!
Pulling the numbers that a stock or +.5 valve size flows enough air to support 400+ HP!! How much more do you need??? Just a thought.
Just me..............................
Thumper
PS we got 25+ actual wheel hp in 90+ temp on a 04 MCS that had stock cam/ic/ headers/injectors/and NO tune!!
Even the SAE corrections are not the best way to do it... if you are in FL. and pull a 25 WHP in 95 degrees, then you KNOW it will be better in a cool 70 degrees and high humidity.. yes?? We quit with the SAE HP or the BHP guess... when we do a mod.. we state the actual WHEEL to the ground HP!!
With STOCK valve size and port work, the engine is still a good drive in traffic .. without boost!! Add a larger valve .. and it slows the velocity into the chambers and the loss in traffic is a given.. just read all the past posts... OR look at their dyno sheets!! If it is a track car.. then all we try to do is out the window... they are never below the power curve in the 4000-4500 rpm range... who needs trafic lite performance.... they need all the top end they can get!! Huge valve and huge ports!!
We are now going to a .5 mm over size. valve.. the loss of the low to mid range is corrected with the correct port and valve work ( under the valve) WE feel that more than a stock valve size or a +.5 mm size is good to talk about.. but the dailey comute to work, or the traffic lite under the boost level sux!! Actually the stock heads are a great head... the valve size is good ( two of them remember..??) As for the bottleneck on the MINI.. dont think so.. yes there is more power in head work, but the stock head is great!!
Pulling the numbers that a stock or +.5 valve size flows enough air to support 400+ HP!! How much more do you need??? Just a thought.
Just me..............................
Thumper
PS we got 25+ actual wheel hp in 90+ temp on a 04 MCS that had stock cam/ic/ headers/injectors/and NO tune!!
Last edited by Thumper460; Nov 25, 2007 at 03:25 PM.
Guess I should've posted this here. https://www.northamericanmotoring.co...58#post1895358 This shows my experience w/ the S1 Valves in a CHR Head. Hope The Ferreas hold up better....
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