I am building a 351 to go in my 91 f250 and was have the short block done and am looking at head options. Does anybody have any solid numbers on how much gt-40 heads would be worth over stock. What about stock heads upgraded to gt-40 valve sizes. I am running a Crane SD friendly cam and don't realy want to convert to mass air at this time. It looks like the gt40p heads would be best stock option but then I will have exhaust issues. Realy was wondering if I wouldn't be better of in putting the money in headers and cat back exhaust and just doing a good valve job on the stock heads.

 

Best for truck HP and torq is to have the stock heads ported.

 

Yeah if your not going to Mass air I'd say go with the exhaust upgrades and very slight head upgrade. The speed density can't handle a big change in air flow. When you start changing the cam and heads your better off with MAF.


Not sure if just smoothing out the bowls and port matching would bother a SD system or not. Or an intake change. Maybe someone who's done some of these upgrades on a non-MAF will have some info.

 

We run a 302 89 F150 with E7 heads fully ported by us. All else is stock runs fine. We have found EFI and SEFI respond better to air flow increases than they do to bigger cams. Upping the fuel pressure a bit might be all thats required. More HP and Torq can also be had with good port work than a hotter cam.

 

My heads are E5's which look to be about the same as E7's. Is there any major differnce between the two? Exhaust ports look pretty restrictive with those big thermactor bumps in them. I thought about just gasket matching and removing those nasty bumps in the exhaust trac.

 

Bottom line is E6s and 7s are basicly the same except the combustion chambers. The E6s I would stay away from. E5s I am not shure about but most other SBF heads are quite similar to E7s and once our port program is run on them come in around 220 CFM @ .5 lift with stock valves. Stock air flow is around 150 to 160 CFM. After porting your bigest restriction is the intake manifold. The lower can be ported to match the heads for some more power. At this point the engine is capable of around a 100 HP increase with the stock cam. This is also the breaking point were the FI needs big bucks sunk in it to keep fuel metering up to the available air flow.

 

You say that you don't want to convert to MAF at this time....but MAF/SD designates what kind of head you're going to use. So you need to make the decision of whether or not you're going to switch over to MAF now.

If it were me, I would swap over to MAF, and get some GT-40Y heads. I got the GT-40Y heads for my 393 stroker, they're a "take off" version, they've been bolted on a long block but never fired. They were removed and re-sold at a cheaper price. For $700 they're a good deal. I got them from Diversified Products, I can find their contact info if you're interested. My 393 is going to make about 400 horse so they'll do the job on your 351. I got my MAF conversion kit used for $400, you can piece one together for cheap too. Research it, MAF is worth it, and it's not very hard to do. Do a search for "MAF conversion" or "maf conv" in the 87-96 forum.

 

Just what are you trying to do with your engine fruz4. I would stay away GT40P heads the GT40s are ok. Reason the P head plug location interfers with air flow across the combustion chamber. If your looking for a better truck motor the E7 style heads ported are the ticket. The GT40s with there large port volume need a larger or higher RPM engine to reap there benifits. What are your cam spec's?

 

So where are these E7 ported heads available at? BTW are the "Y" heads the same as the "P" heads? I was looking at running edelbrock heads.......should i not?

 

Not familiar with the Y head designation woundering if he ment X heads which I believe are aluminum P heads. I looked in several of the FRPP catalogs and havent found them yet.

 

One again as to head choice. Your peformance desires should dictate head choice. Economy, drag race , street/strip, oval track, economy, towing, boat, etc all require different set ups.
Example am currently building two engines a 351C for a Pantera with low gearing the engine will produce 650 to 720 HP between 8500 and 9000RPM.
Another engine is a 302 it will produce around 400 to 430 HP at 6000 and is going in a 4000 pound 87 Grand Marquis. These engines have totally different air flow requirments

 

What if you were going to build a truck motor with a MAF conversion headers Edel intake and a cam that is larger than stock? Like say a 350hp or better motor that is good for towing yet will hall **** when it needs to like jammin up a hill in traffic or something? Or do i even need to convert to mass air to do this? Will speed density be ok?

 

Some what depends on your starting point. A 302 truck motor to 350 HP most likely wouldnt work well with speed density. A say 351 Lightning engine before MA might.
You must figure air flow usually limited by the intake. Say like my 400 HP 302. Around 215 CFM with the intake attached. To produce the 420 HP it would be capable of I would check injector size requiement to support that power at system design pressure. This works out to a 42 LBS injector. Your 19 LBS injectors wount support that even at 100 % duty cycle. 30s just might. Problem here the computer wont drive any thing bigger that the 19s. So here comes the after market MAS air which can be set up to trick the computer into running bigger injectors. I have seen this work and not work. My choice with this big of a jump would be a complete after market laptop programable system or back to carbs. dding up the cost of upgrading everything from the fuel tank forward I went carb much lower than the 4000 to 5000 needed for FI or SFI.

 

egoman are you plannig to pass Cali emissions? If so my sugestion is port your stock heads get the better intake up your fuel pressue a bit it will supprise you as the big torq gain is incredable which is what you want for a truck. I wouldnt even go the cam route.

 

The GT-40 series heads go like this....

GT-40 iron (barely above an E7)
GT-40p (used on explorers and montaineers, need special manfold/header design)
GT-40Y (turbo-swirl design, mid-grade aftermarket head)
GT-40X (better turbo-swirl design, slight step above Y head)
GT-40Z (race head used on high performance engines typically not daily drivers)

Egoman, you're going to have to place you're own thread. Your 2nd post brings it past this threads subject. Sorry man, but this is considered "hi-jacking", please make your own thread

Here is a description of the GT-40Y heads, http://www.jegs.com/cgi-bin/ncommerc...17&prmenbr=361

The 40 hp figure is not very accurate, it depends on a lot of things. That is probably 40 hp over an otherwise stock engine w/ headers or something like that. The power output really depends on the rest of the setup the engine is going to be using, ya can't really say heads make X amount of power in this situation. It depends on whatever else is being used on the motor.