GT40P Heads - How Much Performance Improvement? |
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Jonny Quest
Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2957 |
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Posted: June-04-2017 at 8:56pm |
Gents:
I have a 1994 PCM High Output "Pro Boss" 5.8 engine. 700 hours on the clock. I keep reading about people upgrading to the GT40P heads. What improvement could I look forward to if I were to add the "P" heads to the current configuration over the standard GT40 heads that I currently have? JQ |
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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velde99
Platinum Member Joined: November-04-2012 Location: Tampa Florida Status: Offline Points: 1108 |
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Think you already have the GT-40 heads on that motor. I'm sure others will chime in- but the HO has Gt-40 heads. Look on your motor. That year would have three lines on the end of the head.
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velde99
Platinum Member Joined: November-04-2012 Location: Tampa Florida Status: Offline Points: 1108 |
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To answer your question. PCM told me 50 HP.
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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Going from GT-40 to GT-40P heads with all else being equal will lighten your wallet and provide negligible gains.
With only 700 hrs your heads should be in good shape and doing the swap, I'd say you wouldn't see any difference at all in performance. It would be easier to change spark plugs though Going from the earlier 240 HP heads to the 40's or 40P's is where people see some impressive gains especially with cam and intake changes |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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But if your GT40's are cracked which many have done, the P's will will leave your wallet heaver than getting another set of plain 40's . Not many Fords came with 40's but every late model V8 Explorer and Mountaineers had the P's so they are easier to find.
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Here is a flow chart from a Mustang site
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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I put P's on my '95 GT-40 motor because I had a crack in the original head, mostly because of cost and availability.
Can't really say if I got any more performance because I also changed the cam at the same time. I can say that the combo netted me some nice performance gains, mostly hole shot and mid range performance. Can't seem to get it over the 50mph mark. All that being said I wouldn't change heads unless you needed to, if your going to upgrade other parts for more HP there's much better power to be made from other heads for a few dollars more. JMO |
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3735 |
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Remember performance is limited by the exhaust. The Marine exhaust may be the limiting factor for higher RPM.
I think there are notes on this in this forum to look up. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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I'm not sure how much merit that argument has, the PCM pyramids look a lot like shorty headers internally (there are cross section pics from Alan if you do a search). Only a few folks have built engines that want to spin more than 5200 or so for peak power, but that doesn't mean it couldn't be done. Even with stock exhaust.
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fgroce
Senior Member Joined: July-05-2016 Location: Georgia Status: Offline Points: 350 |
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If you are going to turn up over 5000 I would highly recommend ARP rod bolts, The stock ones are okay but most Mustang sites recommend not going over 4800 rpms. ARP makes some awesome bolts that can take a beating and stay together. But they are not cheap. You can look at there web site for all the technical details.,
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FGroce
88 Ski Nautique For 28 years Now 2002 Ski Nautique |
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