302 with gt40p heads horsepower

this head is complete with new 1.837 int valves and 1.536 exhaust valves. Even with relatively small valve sizes of 1.85-inch intake and 1.46-inch exhaust, the P-heads flow much better than previous. Small Block Ford 289/302/5.0L/351w 180cc/60cc Aluminum Cylinder Head E42004. They fill that spot between power and budget. Just got through porting one of my gt40p heads today. Most of the time, GT-40 heads are worth a good 20-40hp over stock heads. I guess someone could just do a basic valve job and throw on the GT40 upper/lower intake for a cheap HP boost. I got lucky and found a complete Explorer GT40P engine online. Its increase while significant is still only about that of a decent 351 w, hi im building a nastalgic car so im not going to drag race it but it must go ok ive got a 302 windsor basicly recoed stock but i want to run tunnel rams to go with the the3am would like to put choppy cam and replace the heads any ideas would be much apprecited thankyou, What is the stock head cc of a 1992 f150 302 windsor. SB Ford, GT40 .575" Lift Max Output II Drop in Valve Spring Kit, Hyd Roller, 140 Lb Seat. The GTp heads are like GT 40's with smaller combustion chambers and the spark plugs are relocated for a more efficient burn. AFR 165cc 58cc Heads. This kind of improvement may not seem like much, but the owner of our test car, Jamie Holten, runs in FFW Trophy Stock where three-tenths is a lifetime. The specs are a conservative 212/218 degrees of duration at 0.050-inch tappet lift but offer a really nice 0.512-inch valve lift for both the intake and exhaust. The GT40 and GT40P cylinder heads are highly sought after, but how do they stack up against other cylinder heads, and is it worth it to upgrade the Fox Body's stock heads? many thanks to all you eco-hippies giving me dirty looks and helping me feel llike an overall badass rebel. I don't need tons of power to enjoy the car. never messed with the timing, its at 35* total . If you wanted to make your engine feel strong, these would be a decent investment, but they will require some modifications. Shop by category. i'd love to use these heads,. While the heads were off getting a massage, we turned our attention to the cam timing. Compare. Anyways, I know the gt40ps will bump . If we subtract the 20 hp that the fan is worth, we end up with a gain of 25 hp. Depending on the Headers you have you might be okay. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. He'd be the best source. Per a UEM tech support email I have the Icon IC736 is supposed to be good for GT40 heads when I asked about it. $700.98. We also added an Edelbrock Performer RPM dual-plane intake and a set of 158-inch headers with no mufflers. Consider having the head's intake ports matched to the intake manifold gasket. Stock 93-95 Cobra shortblock (stock cobra cam), GT40X heads, 1.7 rockers, Edelbrock Performer RPM intake, Holley 650, and longtube headers. The factory heads have a boss for the exhaust valve that restricts flow through the exhaust port. Free shipping. the springs are new stock oem ford. Sponsored. Again, assuming this is a nearly stock 5.0L with stock heads, the Weiand Street Warrior dual plane intake and 600 cfm carburetor, its important to not become overly aggressive and choose a big camshaft. When I purchased my "brand new" set of GT40P's, I bought them from an Mustang specific machine shop that used to exist called Central Coast Mustang. Well also assume that this engine is running stock exhaust manifolds. What would be the best cam and springs to use for these heads in a 302 Windsor? In order to make Coyote-type power you will need some expensive, high-flow cylinder heads with a short block that can withstand spinning in excess of 6,500 rpm. Joined: Sun Mar 15, 2009 9:31 am. For both the GT40 and GT40p heads, I STRONGLY suggest upgrading the valve springs. Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page. We know what you're thinking--only two-tenths from an extra 45 hp? Instructions on porting the GT-40p heads here. Test 3: Installed the larger Lunati camagain, no other changes. 1.7 shaft rockers and beehives. I just read about this build on the corral.net. I am working on a set of iron GT40s hoping it goes faster. Using the manufacturer recommended springs for your camshaft are a safe bet. Stock 1989 5.0L HO pistons will work if you can find them. +1 I would go with the regular GT40 heads. 402 HP NA from a HI PO 289 isnt that mysterious of a feat to accomplish with todays SBF Aftermarket parts availability. REMANUFACTURED FORD 302 5.0 COBRA GT40 CYLINDER HEADS. Joined . And agree the cams do help and a few tricks with the heads that I have discovered really make a difference. bmcdaniel, Feb 17, 2004 #7. v8maverick Member. I can tell you that with my 9.503 block, 22cc dished pistons and 64cc heads, I'm at 9.5:1 compression. K.S. For real performance, stock E7TE heads leave a lot to be desired. Your email address will not be published. I would like to know what heads, cam and intake manifold combination to use for the most HP I can squeeze out of that motor. Good on ya Jeff Smith. this is the price for one head. This is what I recommend to everyone who is doing a budget 5.0 build. He'll have to get a gear for his distributor. The reply has so many assumptions that I cant even assume to know the answer. . well i finally did my first ever carb build, ive always been an EFI guy Black 1985 GT: 408w, in the 6's in the 1/8 mile. Or, you could invest in a new set of heads that would also do the same job but you can expect to spend quite a bit more money. Dennis Hilliard of Central Coast says we can expect to gain three-tenths in the quarter-mile. Commonly referred to as Explorer heads, GT-40P iron castings are found on current 5.0-equipped Explorers. This is needed for the steel roller cam. Part of this reason is due to its inherent strength and simplicity, but a lot of it has to do with how little Ford has changed it over the years. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. They were located in Tahachapi CA, and were sold with upgraded springs for $650.00, back in 2002-2003 ish. #3::: Do your homework,get quality parts,dont skimp. Good Luck. The Fora platform includes forum software by XenForo. Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W) - GT40P heads? However I think the opportunity window is slowly closing. Come join the discussion about performance, production numbers, VIN decoders, modifications, troubleshooting, power adders, DIY tutorials, and more! 1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD. hole size 302 is 7/16 and 351 is 1/2 The Fora platform includes forum software by XenForo. There are literally a dozen or so camshaft companies that offer a mild hydraulic roller cam for a 5.0L Ford. Also, the spark plug angle makes it a pain. I have managed to get 402 horse power from a 289 hipo natural aspirated. For 2018, the Coyote makes 460 hp. We've seen what happens from previous Ford experience when power levels above 500 hp tend to either pop head gaskets or saw blocks in half. Actually the regular gt40's in either aluminum or iron are the good ones but the gt40p's are only a slight improvement over regular 302 heads. Just put some 1.7 pedistal rocker arm on along with a mild camshaft (make sure to use the correct valve springs), you will make over 300 flywheel hp. fuel injection system . The GT40 & GT40P heads had a few differences that are note-worthy, the most importantly being the bump in compression. Through Central Coast you can have the heads fully prepped for your combination. If this is beyond your technical ability, you could ask a local machine shop to perform the modifications. We were cruising the 'yard a while back and located a 2000 Ford Explorer with an EFI 5.0L V-8 engine. That's fantastic for the minimal investment we made. An aggressive cam will wake it up a bit. We bolted the Ford to the dyno with a set of 158-inch long-tube headers and an 18-inch collector extension to help the low-speed torque, then we fired up the small-block. On slicks the car went some low 7.70s right at 90mph. What did the heads flow? 68 XR7 & 68 M-100. These heads have been remanufactured using refaced reclaimed Factory Valves. E303 Cam advanced 4 degrees. In an effort to preserve the history of the Early Fox Era, FEP covers the following vehicles: 79-86 Mustang and Capri, 84-86 Mustang SVO, 78-83 Fairmont & Zephyr, 83-86 LTD & Marquis, 80-88 Thunderbird & Cougar, 82-87 Continental, 84-92 Mark VII, 81-82 Granada. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Test 2: Changed to the smaller of the two Lunati camshaftsno other changes. I have a 302 Windsor V8 EFI engine that I converted to a 600 cfm carburetor with a Street Warrior intake manifold. Seriously though if you're not planning on an all-out attack for HP, I'd consider a forged piston out of Probe's SRS line-up. Its always refreshing to see a FORD getting a little face time in your column, even if its a tired 302 with no great expectations of setting the world on fire when the dust settles. (A starter is a motor, windshield wipers use a motor,electric windows use motors) Any one uses that terminology in my shop will be corrected once, only once. While we've seen engine dyno tests performed with GT-40P heads replacing factory E7TE castings and resulting in a boost of more than 25 hp, we have reluctantly set our horsepower gain goal at 25 ponies, as well. A trip to Orlando Speed World provided us with updated quarter-mile times. Ive been building ENGINES for 40+ years. But dont think that adding a bigger camshaft will make more power. If you know him, ask him. ***Most important is theStupid question is the one that was never asked!*** They also have emissions legal heads as well. Never not once have I ever seen a SBF rod bolt create a failure. 87-93-95 Ford Mustang GT40P Engine Cylinder Heads REBUILT 302 351 GT40 SBF OEM | eBay Motors, Parts & Accessories, Car & Truck Parts & Accessories | eBay! Do not ever, ever think about using the tube type manifolds. We did the installation at Holten's place of employment, Motorworks, in Longwood, Florida. I got lucky and found a complete Explorer GT40P engine online. For a better experience, please enable JavaScript in your browser before proceeding. Similar to regular GT-40 heads, the biggest difference between the two is that the P-heads feature a revised spark plug angle which extends the plug into the combustion chamber, putting the flame front close to the absolute center of the chamber, resulting in a smoother combustion process. There is a better way. The results were a major increase in power throughout the entire rev range, with an increase of 60hp at 4500rpm through to a peak of 279hp at 5800rpm. I was thinking the same but the enforcers are $647ea now so $1400 (inc tax) is the entry price for good set of heads. Headers and a camshaft will help but the engine really needs aftermarket 3/8 inch connecting rod bolts and aftermarket cylinder heads. Im a different animal. They are more expensive than standard head gaskets, but they also do the job and are worth the additional money. Yeah, out of a bolt on upgrade, you'd probably be looking at 260-280rwhp ish with supporting mods. I think one of the finer traits of a true car guy, is the patience to put a prized car away and just let it sit for a while rather than selling it when life gets in the way. Finally, we exchanged the Explorer's EFI manifold (which is a pretty good manifold in its own right) for an Edelbrock Performer RPM Air Gap intake and a Holley 750-cfm HP-style carburetor. These are Ford iron GT-40P heads. That's a 40 per cent increase in power from a simple head and cam swap, and one seriously happy Mustang owner! K.S. Rowe studied engineering, philosophy and American literature at Central Florida Community College. One benefit gt40P head will have over other 80's-90's model heads, including the gt40 head, is that it has a smaller combustion chamber much like the original 289 heads. Jeff Smith: It would have been better to know a little bit more about your combination, but the short answer is yeswith a hydraulic roller camshaft, assuming the lifters are in good shape and the roller wheels show no unusual wear, they can be re-used on a new cam with no danger of adverse effects. I'm wondering how these heads will interact with the paxton 1220 sl supercharger I'm trying to put on. HiPo manifolds and Ill be good. LOW-BUCK 302 FORD HEAD UPGRADE Richard Holdener 239K subscribers 189K views 2 years ago WESTECH PERFORMANCE GROUP WHAT'S IT WORTH? The '00 Ford Explorers and Mercury Moutaineers were factory equipped with one of Ford's better 5.0L motors. These are some of the best castings Ford ever produced for this engine, and are still fairly cheap and available used. First, adding headers will improve power on the existing combination. Ford's seminal 302 engine (later re-dubbed the 5.0) has been popular with budget-minded hot rodders for decades. Anythoughts? If you go with a diffrent cam, make sure you change springs, The Trick Flow kit comes with everything for around $130. I have a 5.0 from a 1992 Mustang in my 65. At the dragstrip, we gained two-tenths and 2 mph. This test went so well that we were eager to see what the slightly bigger cam would do. GT40Ps have 58cc. Ford GT40P 302 5.0L 4 Bar Cylinder Head Assembly Pair w/ 1/2" Head Bolt Hole. However realistically, with the amount of money spent modifying the gt40p heads or even those older 289 & 351w heads, you could have even better performing aluminum heads. Sure, you could race-port the existing E7 castings, which many have done, but then you're putting quite a bit of change into stock heads. Yes- thank you. Install a set of GT-40P cylinder heads from a late 1990's Ford Explorer or a set of GT40 heads from an early 1990's Mustang 5.0L. this head fits years 95-01 explorer mountaineer mercury mountaineer . In review, we rescued a used 5.0L Ford from the boneyard, ported the heads, added a cam, carburetor, intake manifold, and headers, and pulled an amazing 376 hp out of the mix. 68 Mustang GT/CS Highland Green, PS, PB & Console, C Code w/C4 & 3.55 8 rear, If you aren't using the GT40P's stock, with maybe a spring upgrade and valve job, they aren't worth it anymore. Because of this, your tuneup will probably need to be modified. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. http://vb.foureyedpride.com/showthread.php?t=89153, http://www.facebook.com/groups/233213650060739/, ascMcLaren & Motorsport/Grand Prix IV Capris, RHD and Other International/Export Models, Mods, Maintenance & Mechanical FAQs/Archive, If this is your first visit, be sure to VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. 1983 Mustang G.T. Scorpion 1.6 roller rockers. For a better experience, please enable JavaScript in your browser before proceeding. You can use the stock roller lifters with any size cam you want. The heads also required some machine work, including screw-in studs, guideplates, and widening the spring pockets for bigger valvesprings. Holley 670 street avenger carb. With nitrous, this is easily a mid-11-second ride. Adding the headers may also require a slight increase in secondary (and possibly primary) jetting to ensure the proper air-fuel ratio, but thats also an easy tuning change. The GT40P cylinder heads had a small combustion chamber ranging from 58-61cc while the GT40 heads had a 63-66cc combustion chamber. According to his data and verified dyno tests with an EFI 302, you can go above this level if you port the stock, lower intake manifold, or upgrade it altogether. I need that part number too! Really hurt too. Ford GT40P 302 5.0L 4 Bar Cylinder Head Assembly Pair w/ 1/2" Head Bolt Hole. . Now he serves as a regular contributor to OnAllCylinders. With no other changes we gained 25 hp using factory iron heads. The SUV indicated barely 120,000 on the clock, and after yanking the valve covers to judge the engine's condition, Tim Moore instantly made the decision to do the boneyard version of a smash-and-grab. 1 - 7 of 7 Posts. I've got gt40p heads for it I'll be running, and can't afford better . (Image/Harrison Creamery). The hardest part of swapping the cam was just getting the timing cover off and back on again. Ford offered a performance head that was a stock part on 1993-1995 Mustang Cobra models and pre- 1997-1/2 Ford Explorers and Mercury Mountaineers equipped with the 5.0 L engine called the GT-40 head (casting ID F3ZE-AA). Tim's junkyard refugee survived the beating and we had a bitchin' story. Purchase any used aftermarket manifold for the 302 that is designed to function in the 3,500 to 6,500 power band. Now we know why Dennis Hilliard of Central Coast Mustang is so high on these heads. Choose a cylinder head before you install the pistons. I'd get the gt40 setup, and put an s trim on it. It took him and yours truly eight hours from start to finish, using air tools and a lift to gain access to the header flanges. I was thinking the same but the enforcers are $647ea now so $1400 (inc tax) is the entry price for good set of heads. All in all, the addition of GT-40P heads to any 5.0 Mustang is a worthwhile venture, especially if you're on a budget (aren't we all) or shooting for the Trophy Stock title. In a lightweight Fox or early Mustang with a five-speed behind it, this would be a great little street engine. I used Lightning heads on my 302, (GT40 not P) with stock rockers on a flat tappet engine. Purchase a set of flat top pistons (from Ford Motorsport, TRW or Keith Black) with machined valve reliefs and designed to provide 10:1 compression with a 59 to 60 cc combustion chamber cylinder head. GT 500; Posts: 8496; Location: Brisbane . Sponsored. Always the weak area in the 289 and 302 is the tiny 5/16 inch connecting rod bolts and the miniscule intake and exhaust ports. This is a common mistake with first-time cam buyers who dont necessarily appreciate that the cam is just one component of the overall engine package. After a couple grand you have a killer set of heads, but there's got to be a less-expensive way of making horsepower. how much HP and torque? The spark plug issue is almost a non-issue. Have fun, be safe, enjoy. are you twisted331 also? Definitely going to use my P heads. 1986 Short block with notched pistons. We started with a 120,000-mile 5.0L out of a Ford Explorer, removed the EFI and DIS, and pocket ported the stock GT40P iron heads with stock valve sizes. I guess I had it backwards, sorry about that, didn't mean to spread misinformation. Would have liked to see a comparison done on the same short block using a set of decently-ported early non-Thermactor iron heads Tracy Blackford, 65 Mustang FB, 331 built with 289 H beam rods and 383W piston, 282S cam, self ported '70 351w heads, Dougs Tri-Y headers. Nice to see actual dyno results instead of "butt dyno" guesses. Features hardened 4140 Chromoly retainers, valve locks, spring shims, a spring height gauge, valve seals, and instructions. Horse Sense: The smaller valves found in GT-40P heads improve airflow velocity. A forum community dedicated to Ford Mustang owners and enthusiasts. $700.98. The best thing to do would be to use a specific break-in oil for the first 200 to 300 miles of use to reduce the change of a potential problem with undue wear. Here is the lowdown on exhaust manifolds and VALVE SPRINGS. These are among the best of the iron Ford Windsor heads as they tend to flow much better than earlier castings. United Engine and Machine sells cheap but decent pistons that will do what you're wanting. Our recommendation would be, rather than change the camshaft, you might want to look into adding a set of long-tube headers and a dual exhaust if the engine is not already so equipped. For a better experience, please enable JavaScript in your browser before proceeding. Limited header choice is certainly a challenge. Find many great new & used options and get the best deals for FORD GT40p 4 BAR HEADS IN GOOD CONDITION w/ONE BOLT BROKEN at the best online prices at eBay! How to Build a Budget 383 Stroker Chevy How do I Increase Horsepower on a 440 Cylinder Head Specifications for a 1969 How to Get More Power Out of a 92 4.3 dragster engine image by Robert Young from, Copyright 2023 Leaf Group Ltd. / Leaf Group Media. at the crank. 68stang351 Founding Member May 16, 2002 850 VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Common sense would suggest that with the heavy lifting complete and the old cam removed, by not installing the new roller lifters along with the camshaft could be asking for the possibility of trouble just a few thousand miles down the road. Those are really good numbers. The older pushrod engines just dont offer the same kind of power potential for their displacement and it all has to do with cylinder head flow. Compare. You keep stock drivability, and stock gas milage if you can stay out of boost. If you're running a stock cam, 1.7 rockers will work perfectly. Stock heads with a fresh 3-angle valve job, shorty headers, T5, 4.10s, stock Explorer intake and stock '88 GT short block with 140,000 miles on it and an E cam in it. If I remember right, non of the GT40P's (later models) had the thermactor smog provisions. Without changing the stock pistons. Building a 302-inch small-block to produce 400 hp is really no big deal, but doing. The entire front accessory drive and timing chain cover must be removed, along with the distributor and intake manifold. 302 .030 over with; Scat Forged Steel Rods, SpeedPro pistons and rings . The gt40p head is considered the best OEM 302 head made. I wouldnt recommend reusing lifters though. Maybe I'll think about a cam swap? I have a very good running stock 1981 302 in a F100 short box. Stock valve sizes? The kit offers adjustable power from 50 to 250 hp with a simple jet change. Win or lose, if you buy the ticket you must take the ride. Not looking for crazy HP. You will have to address the 50 oz balance of the 5.0 engine by getting a 50 oz flywheel. Actually, making around 240 to 250 hp with a near-stock Windsor 302 will feel pretty good. Can anyone give me a little feedback about a '99 Explorer 5.0, and tell me if it's my answer. Plus you will need to drill all the head bolt holes out as the 351W uses larger head bolts. ford 302 sbf gt40p v8 cast iron complete cylinder head and head bolts and head gasket set. Richard Rowe has been writing professionally since 2007, specializing in automotive topics. I have a 432 HP non Hi Po 289 I built. Shop by category. Those heads were unported and had stock valve sizes! This combination should be good for about 400 horsepower and as much as 500 if you opt to use the stronger aftermarket pistons. Take the assembly to a machine shop to have it balanced and install it in the block. fordfan289, Aug 27, 2011 Everything fits, use the stock rockers and pushrods. Going from your heads to the GT40p heads will bump your compression by about a point.so hello bottom end torque. Go for it if you get them super cheap and can get headers/manifolds super cheap as well but otherwise I'd say it's a waste of time and money. Dec 8, 2011. The MPH was there to run a little better but the local track is about terrible. Weiand 7515 xcellerator intake. Assorted screwdrivers, pliers and vise-grips. Best of all, no machining is required to install these on your stock cast iron heads! With. 950.00 us a set and will ship . A bone stock 2bbl early 351w with stock replacement forged pistons (9.0 compression) and dyno headers made 211 Hp . Can I run the new cam with the same roller hydraulic lifters or do I have to change the lifters too? Finding Gt40p heads at the junkyard is getting more and more complicated and if you want to upgrade the heads you have to take into account the costs of the machine shop and compare everything to a set of cheap aluminum heads. Paying a premium for a set of GT40P heads or dumping money into some to get their performance to rival aftermarket is not for me. Application Fits 1979-95 Mustang 302/351 w/ OEM Small Block Ford Heads There are caveats to this plan, however. But don't think that adding a bigger camshaft will make more power. I bought a crate 302 from Downs Ford a few years ago that was producing 320 hp. Add a distributor designed for a carbureted 302 but make sure to install the correct distributor gear for your cam. The only failures Ive had were timing chains and a couple broken rods in a mid 80s 302 with 200,000 miles on it that got about 35 lbs of boost stuffed into it when a pop off valve I bought on ebay failed. You will have to get special headers to fit these heads since the spark plugs are angled differently than normal 5.0 heads. The 5.0L with the GT40 head had a 9.0:1 compression, and the 5.0L with the GT40P head had 9.1:1 compression. Ive bought wrecking yard SBFs and put 20 lbs of boost to them and spin them to 7000 and made 500 HP with several of them. Pride is built, in your garage, with your two hands. GT40s have 64cc chambers. Assuming this will be a daily driver engine, a short duration camshaft, especially when combined with a four-barrel dual plane intake manifold and headers, will deliver extremely snappy throttle response and the whole combination will increase the torque and peak horsepower by somewhere in the neighborhood of 20 to perhaps 35 horsepower. For the most part 302 heads and 351W heads are the same. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. You didnt mention what camshaft you would be choosing or exactly which 5.0L Ford Windsor engine you are working with. Then why did you port the heads and how do you know if you made an improvement. For a better experience, please enable JavaScript in your browser before proceeding. I had those on my car before I upgraded and they were nice heads. Even with a stock Mustang 5.0 cam makes good power. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. In less than an hour, we were ready to test. It's an 86 roller 5.0 engine that had a recent rebuild sometime in the past with keith black pistons, otherwise stock. This one added another 10 degrees of duration over the smaller Voodoo cam, along with 0.020 inch more intake valve lift. built one using a 91' HO short block with a set of AFR 165 heads, Weiand . I may do some port matching and a little cleanup, otherwise just a set of springs and cam and see what I have. They suffered from poor aftermarket support up until about 15 years ago when it really came on strong. These cast piston short-blocks are not quite as good as the forged piston 5.0L that came in Fox-body Mustangs, but the GT40P heads flow much better than earlier 5.0L heads. MAC is the only manufacturer of these headers, and the parts we installed fit like a glove with no problems whatsoever. Not to mention, they will run circles around GT40P's out of the box. Both swaps made more sense when parts were readily available at the bone yard for cheap. Once you get into the FoMoCo aftermarket aluminum GT40s though, all bets are off. You should be able to get away with a 150 to 200 horsepower shot later, but it's best to start out small and work up. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. These engines came with the GT40P head, which even with its small valves, offers really good performance. For the first test, we were reusing the stock Explorer cam, so the engine didn't need any break-in time. T5z and 3.89 9" TL rear. I spin it to 6500 and thats about it. I view the GT40P heads similar to Granada brakes. Despite adding 30 degrees of intake duration, this cam improved torque throughout the entire test from 3,000 rpm on up.