Versatility with 351w heads

[92SupraComp]

Sorry, but you are at 310HP RATED from PCM. NO TESTING WAS EVER DONE. PCM does NOT have actual dyno numbers, they literally pulled them out of air and rated the motors. The older 351W with 1:1 and 1.52:1 trannys were rated 230HP. Then with the angled 1.23:1 because of the level motor and now 10* base timing instead of 6* the exact same motor was rated at 240 HP. THen they released the HO model which was rated in the 260's or 270's range.. Then my model, PCM 5.8 HO Pro Boss Pro Tec ignition RATED @ 285HP. Then they came out with Throttle Body Injection which was PCM 5.8 HO Pro Boss EFI RATED @ 320HP, that ended QUICK because the TBI was not good... Then came the PCM 5.8 GT40 EFI MPI RATED @ 310HP...

None of these CC guys have Dyno'd their motors yet but they RATING them at 320HP+ and they pull MUCH harder than the RATED 310HP GT40 MPI engines... I do a lot of reading and try to make sure I understand things correctly, but please, if I am wrong, CORRECT ME!

[Blackntan90]

I have the 351/1:23.1 PCM combo in my Mariah. While you and the book say it is 240 hp, I cannot win a tug of war with it ever! I would love more top end though...without losing hole shot!

[haugy]

My buddy, who I'm trying to get join in here, said his comp was feeling very tired, 86 Comp with some 1,000+ hours. So he's redoing stringers, but really wanted more power while he's at it.

He's looking at stroking it, putting GT-40P heads, new intake, and a 750cfm marine carb on it. That ought to pep it up a bit, by our estimates up to 400hp. On my 351w I think I may go the same route. But with my exhaust manifolds (headers) they are custom made, so I needed heads that match up exactly like factory 1989 351w heads that are non GT-40. I think from what I read I should be able to up the power quite a bit. My concern is bottom end. But since my engine has a 4-bolt main, I think if I stroke it, put a girdle on it, and don't go overboard on the heads, the bottom end with a forged crank should hold together for what I use it for.

He's wanting a monster power ski-boat. But I warned him about long hard high rpms that these boats see. He's a barefooter so he wants some serious speed and power from it.

[92SupraComp]

Any ford 351W or even 289/302W head will bolt right up... They are drop in replacements for a reason...

Also, we have easily 1,500+ hours on the Comp and its missing the GT40 heads, still runs strong. Never rebuilt. Just oil changes, rebuilt the carb once, and leave the electronic ignition alone...

[Jetlink]

My buddy, who I'm trying to get join in here, said his comp was feeling very tired, 86 Comp with some 1,000+ hours. So he's redoing stringers, but really wanted more power while he's at it. He's wanting a monster power ski-boat. But I warned him about long hard high rpms that these boats see. He's a barefooter so he wants some serious speed and power from it.

Is he wanting to pull down trees or a house? Go god man!!!

[blackstang]

If he's going to stroke it I suggest going with a much better head than the GT40P. If he's worried about going with aluminum heads, he could get the Dart Iron Eagle series head that will way out perform the GT40P. The GT40P head is a great budget series head, but will not provide the airflow to achieve maximum benefits from a 351 based stroker motor. Heck if he wanted a budget aluminum head you can get the Procomp head for pretty cheap. I've seen many of those perform out of the box well on 351 based motor in Fox Mustangs. They are not my first choice of a cylinder head but if looking for decent power on a budget they would be better than GT40P.

[haugy]

I thought the GT-40P heads were supposed to be way better than stock and GT-40. I'm clueless and I've never tried any of the other heads or done much reading up on them. If they worked, great. He's on a budget but from what I can tell he'll up the ante for good parts.

But from what I can tell, building up the bottom end with good crank, pistons, rods, etc is all good for solid power. But the wrong heads and intake can kill all that effort and $$$.

[92SupraComp]

Yes the the GT40P heads are a little better than the GT40 heads and far better than the stock heads... The biggest thing is, the stock heads, are complete SHIT! They truly are awful heads that should never have been made... Thats the thing, it doesn't matter what brand, US or china head, the 351W will perform heaps better with any other head that even remotely flows more than the stock ones... Thats why people are happy with just GT40P's. It a HUGE upgrade from the crap heads... The 351W has MUCH potential but ford never bothered... The cheapest Edelbrock heads flow far better the GT40P's. But if you go look at the numbers, the huge gap between the Edelbrock and GT40P heads is just as big as a gap between the stock heads and the GT40P heads, they are that bad...

[haugy]

Wow, didn't know that. Damn, and I've been running stock heads on my 351w from my Comp on my rockcrawler for almost a decade now. Seemed peppy enough. HA!!!

[blackstang]

I thought the GT-40P heads were supposed to be way better than stock and GT-40. I'm clueless and I've never tried any of the other heads or done much reading up on them. If they worked, great. He's on a budget but from what I can tell he'll up the ante for good parts.

But from what I can tell, building up the bottom end with good crank, pistons, rods, etc is all good for solid power. But the wrong heads and intake can kill all that effort and $$$.

GT40 heads are often confused. GT0 iron heads came on everything from the Cobra Mustang 93-95, first gen Lightning trucks and 95-early 96 Explorer. By late 96 the Explorer GT40 head was revised to the "P" head for emissions reasons according to Ford. The main difference being revised plug angle (PITA) to get to number 5 on a Mustang with shorty headers and a slightly smaller combustion chamber.

They also made/make many different versions of the GT40 head in aluminum that were available through Ford Racing over the years.