Turbo Build With Too Big Of Heads
Turbo Build With Too Big Of Heads So helping my son build a single turbo 5.3 . Shocking Right ?
But here is the twist the builder knows I have a set of T.F. 225 CNC heads
setting in my garage . He wants me to take out the 2.055 intake valve
and replace it with a 2.020 valve so that it will work on a sub 4" bore .
His reason for this is better flowing head . More horse power with less boost .
So I ask you turbo head guys and gals is he crazy or will this really work ?
But here is the twist the builder knows I have a set of T.F. 225 CNC heads
setting in my garage . He wants me to take out the 2.055 intake valve
and replace it with a 2.020 valve so that it will work on a sub 4" bore .
His reason for this is better flowing head . More horse power with less boost .
So I ask you turbo head guys and gals is he crazy or will this really work ?
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
Lets say you can make X Horsepower with 12 PSI on stock heads.
You can make that same X horsepower with 9 PSI on the expensive heads.
What exactly are you making any worse by just running that extra 3 psi? Certainly not your wallet.
How much hotter will the engine running the 12 psi run than the 9 psi engine? At 12 vs 9 psi it might not be a big deal, but at some point in a street driven car making the same power with less boost has to be a benefit.
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Drake Offy Head Design Hi ALL, the BEST Racing Engine of ALL TIMES, TO THIS DAY, is the Drake Offy. (Miller)
The Intake Ports and Valves where close in SIZE to the Exhaust Ports and Valves.
My ANSWER is as your "builder" asked.
I would even go further 2.00" Intake and WITH a 1.65" Exhaust Valve Size.
Tony M. cast me SBC Turbo heads with 1.7 Exhaust Valve when he worked for AFR.
Lance
The Intake Ports and Valves where close in SIZE to the Exhaust Ports and Valves.
My ANSWER is as your "builder" asked.
I would even go further 2.00" Intake and WITH a 1.65" Exhaust Valve Size.
Tony M. cast me SBC Turbo heads with 1.7 Exhaust Valve when he worked for AFR.
Lance
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Verdad Gallardo One thing the I failed to mention is the heads was practically given to me .
Pick them up with a set of forged H beam rods with ARP 2000 bolts and a
set of forged pistons all for $500 .
So for me I think I can sell off the piston for $200 ?
The rods at that point cost $300 .
This puts the heads free . If I put a grand into the heads I don't think it will hurt the wallet .
This is assuming it will make more power with less boost .
And yes less heat .
Hi ALL, the BEST Racing Engine of ALL TIMES, TO THIS DAY, is the Drake Offy. (Miller)
The Intake Ports and Valves where close in SIZE to the Exhaust Ports and Valves.
My ANSWER is as your "builder" asked.
I would even go further 2.00" Intake and WITH a 1.65" Exhaust Valve Size.
Tony M. cast me SBC Turbo heads with 1.7 Exhaust Valve when he worked for AFR.
Lance
The Intake Ports and Valves where close in SIZE to the Exhaust Ports and Valves.
My ANSWER is as your "builder" asked.
I would even go further 2.00" Intake and WITH a 1.65" Exhaust Valve Size.
Tony M. cast me SBC Turbo heads with 1.7 Exhaust Valve when he worked for AFR.
Lance
Intake Valve Diameter (in): 2.055 in.
Combustion Chamber Volume (cc): 65
Intake Runner Volume (cc): 225cc
Exhaust Runner Volume (cc): 80cc
Combustion Chamber Style: Heart
Intake Port Shape: Cathedral
Intake Port Location: Standard
Exhaust Port Shape: Oval
Exhaust Port Location: Standard
Exhaust Valve Diameter (in): 1.575 in.
Intake Valve Angle: 13.50
Exhaust Valve Angle: 13.50
Lance what valves would you run with these specs ?
Thanks !
Joined: Mar 2007
Posts: 1,149
Likes: 62
From: Saskatchewan, Canada - where arguing "DA" is for the slow and weak...
I am pretty certain the more pressure you put against the compressor wheel acts against the turbine. It is probably in here somewhere:
http://www.springer.com/cda/content/...879-p177335125
My general understanding is you build the best N/A engine possible and then add a turbocharger. But, then again I haven't built 1000 boosted engines and have no real credentials to back up my internet musings.
Personally I'd run the heads as built if the big valves clear and carry on, the air fuel mixture is just going to flow right on in. Squish. Bang. Blow.
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
The correct answer is: An absolutely NEGLIGIBLE amount. People spend WAY too much time worried about running too much boost, to the point where they will spend thousands to make the SAME power, as long as they can keep the boost down.
Pressure = heat. More pressure, more heat. Measuring things in "pounds per square inch" is useless agreed, and I think that the builder gets this. I don't know about the rest of his logic, but I think he's trying to keep the boost and heat down as it only denotes the presence of a restriction, try measuring things in "cubic feet per minute" because air flow makes more sense. Air mass is the only thing that matters when filling cylinders - in my opinion. Arguing PSI is about as profound as debating dry airflow through a wet port cylinder head - again in my opinion.
I am pretty certain the more pressure you put against the compressor wheel acts against the turbine. It is probably in here somewhere:
http://www.springer.com/cda/content/...879-p177335125
My general understanding is you build the best N/A engine possible and then add a turbocharger. But, then again I haven't built 1000 boosted engines and have no real credentials to back up my internet musings. I basically agree with this too. There are plenty of guys here who build crazy powerful motors that will say buying aftermarket parts to increase power is pointless when you can just turn the boost up. But there HAS TO be a point in time where that doesn't work out so great anymore. So I have a serious question - if your goal is 900rwhp what is going to be the difference in power curve, driveability and longevity between a SBE 5.3 with an LS6 intake and stock 243 heads and a SSBE 5.3 with a good set of aftermarket heads and one of the popular aluminum intakes manifolds? With each being cammed appropriately. One is going to need less boost than the other obviously. How does that translate to how it feels on the street and how it feel on the track and how long it lives? What about a 1,200rwhp motor. There is a point where adding boost is not going to work any more, no?
Personally I'd run the heads as built if the big valves clear and carry on, the air fuel mixture is just going to flow right on in. Squish. Bang. Blow. Now this feller understands how a motor works, lol. I'd also run the heads and run them untouched unless there is an issue with doing so, like they dont fit. I cant imagine a whole hell of a lot of difference between the two different valve sizes, especially given the fact that air is being forcibly pushed into the chamber.
I am pretty certain the more pressure you put against the compressor wheel acts against the turbine. It is probably in here somewhere:
http://www.springer.com/cda/content/...879-p177335125
My general understanding is you build the best N/A engine possible and then add a turbocharger. But, then again I haven't built 1000 boosted engines and have no real credentials to back up my internet musings. I basically agree with this too. There are plenty of guys here who build crazy powerful motors that will say buying aftermarket parts to increase power is pointless when you can just turn the boost up. But there HAS TO be a point in time where that doesn't work out so great anymore. So I have a serious question - if your goal is 900rwhp what is going to be the difference in power curve, driveability and longevity between a SBE 5.3 with an LS6 intake and stock 243 heads and a SSBE 5.3 with a good set of aftermarket heads and one of the popular aluminum intakes manifolds? With each being cammed appropriately. One is going to need less boost than the other obviously. How does that translate to how it feels on the street and how it feel on the track and how long it lives? What about a 1,200rwhp motor. There is a point where adding boost is not going to work any more, no?
Personally I'd run the heads as built if the big valves clear and carry on, the air fuel mixture is just going to flow right on in. Squish. Bang. Blow. Now this feller understands how a motor works, lol. I'd also run the heads and run them untouched unless there is an issue with doing so, like they dont fit. I cant imagine a whole hell of a lot of difference between the two different valve sizes, especially given the fact that air is being forcibly pushed into the chamber.
Compressor Maps Hi SS, The Pressure Ratio does effect the Compressor Efficiency. (for Mike)
Please state the turbo part number/manufacturer, we supply BW turbos often.
The engine will flow an amount of air AND with RESPECT most consider the inlet air entry into the cylinder most important with LITTLE CONCERN for the air exit out of the cylinder.
The turbo"match" IS BASED on engine air flow ONLY.
YOUR question (S/S) is answered by a "NO CHANGE" the changes will cost $$$ with other items of MUCH GREATER concern.
The MOST important item is Camshaft Specification ?
What will be the Bore Size ?
The block, a GEN-IV AL ?
Lance
Please state the turbo part number/manufacturer, we supply BW turbos often.
The engine will flow an amount of air AND with RESPECT most consider the inlet air entry into the cylinder most important with LITTLE CONCERN for the air exit out of the cylinder.
The turbo"match" IS BASED on engine air flow ONLY.
YOUR question (S/S) is answered by a "NO CHANGE" the changes will cost $$$ with other items of MUCH GREATER concern.
The MOST important item is Camshaft Specification ?
What will be the Bore Size ?
The block, a GEN-IV AL ?
Lance
Some real good info in both post !! The heads are are free to me . If my son spends a grand on them no big deal . Then he will have a set of heads that will work .
Hi SS, The Pressure Ratio does effect the Compressor Efficiency. (for Mike)
Please state the turbo part number/manufacturer, we supply BW turbos often.
The engine will flow an amount of air AND with RESPECT most consider the inlet air entry into the cylinder most important with LITTLE CONCERN for the air exit out of the cylinder.
The turbo"match" IS BASED on engine air flow ONLY.
YOUR question (S/S) is answered by a "NO CHANGE" the changes will cost $$$ with other items of MUCH GREATER concern.
The MOST important item is Camshaft Specification ?
What will be the Bore Size ?
The block, a GEN-IV AL ?
Lance
Please state the turbo part number/manufacturer, we supply BW turbos often.
The engine will flow an amount of air AND with RESPECT most consider the inlet air entry into the cylinder most important with LITTLE CONCERN for the air exit out of the cylinder.
The turbo"match" IS BASED on engine air flow ONLY.
YOUR question (S/S) is answered by a "NO CHANGE" the changes will cost $$$ with other items of MUCH GREATER concern.
The MOST important item is Camshaft Specification ?
What will be the Bore Size ?
The block, a GEN-IV AL ?
Lance
He has a Borg Warner 75mm x 83mm 1.1 A.R. T4 foot .
Cam has not been specked at this point .
Bore is looking like 3.8" .
Block is a gen III cast iron .
So we can all agree that spending a bucket load of cash on heads isn't worth it in a forced induction build. What about if you are building a forged 370 to replace your sbe ls1 and want to "freshen" up the heads at that time any way? Might as well grab some 799/243 heads for under $400? It's not going to hurt and $400 extra $ on a forced induction build isn't much in the grand scheme of things.
My general understanding is you build the best N/A engine possible and then add a turbocharger. But, then again I haven't built 1000 boosted engines and have no real credentials to back up my internet musings.
Personally I'd run the heads as built if the big valves clear and carry on, the air fuel mixture is just going to flow right on in. Squish. Bang. Blow.[/QUOTE]
This looks to be sound advice. A n.a. motor needs good heads to make power. No difference then a boosted motor.
The heads we are talking about will no fit the the 3.78 bore size of the 5.3.
Personally I'd run the heads as built if the big valves clear and carry on, the air fuel mixture is just going to flow right on in. Squish. Bang. Blow.[/QUOTE]
This looks to be sound advice. A n.a. motor needs good heads to make power. No difference then a boosted motor.
The heads we are talking about will no fit the the 3.78 bore size of the 5.3.