im building a 11.2:1 compression 306. wiseco flat top pistons with two valve reliefs eagle sir I beam rods eagle crank. 58cc heads springs good to 550 lift.1.94 intake valve 1.54 exhaust.1.6 roller rockers .050 compressed thickness head gaskets. its going to be a daily driver motor on 93 pump gas. my goal is to hit 310-320 at the wheels through the aod. I don't want a cam that is overly aggressive but I want the lope noticeable and want a cam that wont be to much lift that I have to worry about ptv clearance or having to put a converter on it to have it work properly since the aod will be swapped for a tko down the road
Best Cam For High Compression 306
- Thread starter jdemolet
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first off you want to select a cam that works in the rpm range you are going to run the engine in about 80% of the time. for a daily driver that means the 1000-5000 rpm range. you can fudge that some depending on the rest of the combination. for your engine, especially running 11:1 compression and i do hope you are running aluminum heads, i would go for something like a comp cams 270 extreme energy cam, or perhaps this cam is more to your liking;
31-601-5 - Hydraulic Flat Tappet Camshaft
31-601-5 - Hydraulic Flat Tappet Camshaft
I'm going to use the obligatory "get a custom cam" comment. But if using an ots grind the comp 268 or 270 would be good. Even a tfs 1
Your not going to hit 310 through a stock aod with any cam because your heads are to small and are not set up to flow enough air. The cam isn't going to be the limiting reason. Also the auto eats about an extra 8-10% of your flywheel hp compared to a manual.
What's the spring rate? There is more to the valve spring than just max lift numbers. Some cannot handle the ramp rates of a roller cam compared to a hydraulic lifter ie. Also are you just looking for a dyno "number" or just want a nice hard running street motor? There needs to be a complete plan of what you want to do.
Easiest way is to add cubic inches. With a really mild cam a 331 will make 300+ to the wheels. With a 306/those heads/aod you're going to be hard pressed to get there. You could see high 280-290's(I'm just not familiar enough with Flotech). I know with AFR or TFS heads and a tfs 1 cam (or equivalent) with the proper intake,MAF,exhaust, etc most autos make around 280-290.
For 3 years I ran a 10.15:1 331 with ported gt40's and accompanying valve job. I used a n41 cam and shorty headers, all thru a t5. Car weighed 3390 with me in it the day it trapped 108.25 in the 1/4. That came out to 305rwhp using online calculators. Probably plan on 10-15 less with an auto.
Joe
Joe
you do realize thats a flat-tappet cam and not a roller right?
300rwhp i would say wouldnt be impossible, but it will be hard to get with the gt40 rip-offs. people HAVE done it with iron gt40/gt40p's though, just takes the right setup (i.e. custom cam, matched intake, roller rockers, and one hell of a tuneup).
imo if you want to use what you've got and use an ots cam, stick with something along the lines of a comp xe270hr, or tfs stage 1. if you can upgrade the springs to handle them, an xe274hr or tfs stage 2. but even those last 2 might be too much for those heads.
Grabbin' Asphalt
5 Year Member
I have a similar gt40 set up, my trq numbers make this car fun, very easy daily driver, my E cam is holding me back however, ex264hr or ex270hr would be the Top Limit I would risk keeping it a daily driver. But i seen the ex264hr on someones dyno on another forum(with no scrolling pop up adds) around 305-315rwhp.
If it were me...
1. Gt40 xe264hr with 302/306 -ported, milled worked etc
2. 331 with xe270hr or xe272hr similar grinds etc
obviously if you have the funds for better heads, but heads can always be added later if the 331 funds are tight. Daily Driver is a key word here.
If it were me...
1. Gt40 xe264hr with 302/306 -ported, milled worked etc
2. 331 with xe270hr or xe272hr similar grinds etc
obviously if you have the funds for better heads, but heads can always be added later if the 331 funds are tight. Daily Driver is a key word here.
Yeah, except 5.0ho's (like the op's and every other fox since 1982) are all factory rollers.
What parts do you already have? Just the Flotech heads? Do you have the wiseco pistons/306 shortblock? Or is this just a purposed build? If you already have this long block combo I'd just add an ots cam/proper induction system and run it.
If you're just planning around those heads and haven't built the shortblock yet I'd build a 331. Again I'd probably use an ots and good intake etc. and run it.
If you can start over I'd buy some better heads and build a 331/347 with a custom grind. You could build a daily driver with an easy 325-350 rwhp/tq. Through the aod.
If you're just planning around those heads and haven't built the shortblock yet I'd build a 331. Again I'd probably use an ots and good intake etc. and run it.
If you can start over I'd buy some better heads and build a 331/347 with a custom grind. You could build a daily driver with an easy 325-350 rwhp/tq. Through the aod.
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